Research ArticleEvaluationofParticulateMatterCaptureandLong-TermCloggingCharacteristics of Different Filter Media for PavementRunoff Treatment

Zhengguang Wu1 Yanjuan Qi1 Aihong Kang 1 Bo Li 1 and Xueling Xu2

1College of Civil Science and Engineering Yangzhou University Yangzhou 225127 China2Shanghai Telsafe Engineering Technology Co Ltd Shanghai 200120 China

Correspondence should be addressed to Aihong Kang ahkangyzueducn

Received 27 June 2020 Accepted 14 July 2020 Published 27 August 2020

Guest Editor Hainian Wang

Copyright copy 2020 Zhengguang Wu et al )is is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

)e removal of particulate matter (PM) by filter media during filtration process can mitigate the pavement runoff pollutioneffectively However this process also makes the filter media prone to clogging To better understand the size ranges of PMcaptured by filter media and the subsequent impact on the clogging process filtration test and clogging test were conducted on fivetypes of filter media )e effect of layer thickness and grain size of different filter media on particle removal efficiency wasevaluated based on the results of PM removal rate and the particle size distribution )e subsequent long-term cloggingcharacteristics of different filter media were also investigated )e results showed that filter media presented different capabilitiesto capture PM which could be enhanced by less layer thickness or finer grain size Normally PMwith the size range of over 49 μmcould be captured effectively if proper layer thickness and grain size of filter media were selected Besides PM removal rate was notrelated to the clogging resistance of filter media )ough it can capture a larger amount of PM Vesuvianite still maintainedremarkable clogging resistance)e results will be beneficial to filter media selection and system design optimization for pavementrunoff treatment

1 Introduction

Pavement runoff has been considered as a major pollutionsource to adjacent receiving watershed [1ndash3] )e pollutantsin pavement runoff mainly consist of particulate matter(normally characterized by total suspended solids TSS)chemical oxygen demand (COD) nutrients (normallycharacterized by total nitrogen TN and total phosphorusTP) and heavy metals [4] which commonly have highlypolluted concentrations [5 6] Filtration and infiltrationsystems are effective in mitigating the pavement runoffpollution [7ndash11] although the systems were developedinitially to control the runoff volumes

Unfortunately those systems are prone to cloggingleading to deterioration in (in)filtration capability [7 12]Filtration and infiltration systems are normally filled with

specified filter media (Figure 1) such as Zeolite Diatomiteexpanded vermiculite Ceramsite Vesuvianite furnacesteelSlag [13] and granular activated carbon [14] along withconventional filter media such as soil sand and gravel )epore structures of filter media will be blocked gradually asthe suspended PM is captured [15ndash18] )erefore the sus-pended PM in runoff has been considered as a dominantcontributor to clogging [19 20]

)e PM in pavement runoff originates from road-de-posited sediments accumulated on the pavement surfaceswhich will be washed off during rainy days [13] )e con-centration and the particle size distribution (PSD) of PM arehighly related to the clogging phenomenon Research hasbeen conducted to characterize the PM in pavement runoffIn addition to the widely used gravimetric concentrationindices of TSS and turbidity PSD of PM has also been

HindawiAdvances in Materials Science and EngineeringVolume 2020 Article ID 5012903 15 pageshttpsdoiorg10115520205012903

determined Charters [21] investigated PSD in the untreatedrunoff collected from pavement concrete roof copper roofetc in New Zealand and the results showed that pavementrunoff contained much higher TSS concentration while thepeak particle size range was between 60 and 100 μm Shenet al [22] characterized PSD in pavement and roof runoff inBeijing and found out that particles with the size ranges of38ndash74 μm and 125ndash300 μm accounted for the majority of thePM in pavement runoff Winstonrsquos research [23] revealedthat median particle size of PM varied from 31 to 144 μmaccording to 43 road runoff events in North Carolina Liet al [24] monitored three highways in west Los Angeles forthree rainfall events and the results showed that more than97 of the particles had a size of less than 30 μm Jartun et al[25] investigated 21 runoff samples in Norway and reportedthat the particle size varied from 13 μm to 646 μm Ingeneral the PM in untreated pavement runoff has normallya size range of 0ndash1000 μm

Due to the differences in angularity texture chemicalcompositions etc different types of filter media are sup-posed to possess various pore structures [26 27] and ca-pabilities to capture particulate matter Furthermore thePSD changes of PM in runoff treated by filter media can notonly reflect the capability of filter media to capture PM butalso infer the size ranges of captured PM which will causeclogging However current research focused on the PSDanalysis of untreated pavement runoff Few studies havebeen performed to evaluate the PSD changes in treatedrunoff )erefore it is still not well understood which sizeranges of PM could be captured by filter media and thesubsequent impact on the clogging process

)erefore the primary objective of this study was toevaluate the capability to capture PM and the correspondingclogging characteristics of different types of filter media Toachieve the objective synthetic runoff was preparedaccording to in situ pavement runoff )en the PM removalrate of five types of filter media with different layer thicknessand grain size was investigated by laboratory filtration testMoreover the PSD changes in the untreated and treatedrunoff were determined by a laser particle analyzer and thePM capture capability of the filter media was comprehen-sively analyzed Eventually long-term clogging simulation

tests were conducted so as to evaluate the clogging char-acteristics of the five filter media

)e methodology of this research is depicted in Figure 2

2 Materials and Experimental Methods

21 Synthetic Runoff Preparation Considering that a largeamount of runoff with stable and consistent characteristicswas required for the laboratory test synthetic runoff wasprepared as an alternative according to the previous in-vestigation results of the in situ pavement runoff [13]Synthetic runoff was prepared by dissolving pavement de-posited dust and chemical compounds into deionized water)e target concentrations and selected chemical compoundsare listed in Table 1

As shown in Table 1 the heavy metal elements of Zn andPb which mainly originate from vehicle tires and fuelsrespectively were selected for analysis since they are thedominant ones in pavement runoff)e PSD of the syntheticrunoff which was close to that of in situ pavement runoffhad d50 and d90 of 1936 μm and 4007 μm respectively

22 Filter Media Five typical types of filter media used infiltration systems were chosen for this study which wereZeolite Ceramsite Slag Diatomite and Vesuvianite )eypossess various porous structures and compositions (Fig-ure 3) and can capture particulate matter by retention andorabsorption along with some other physical and chemicalinteractions [13] Besides three different grain sizes of1ndash3mm 3ndash6mm and 6ndash8mm which are widely applied inengineering projects were also prepared for each filtermedium

Air-void fraction of every filter medium with each grainsize was investigated in accordance with Chinese standardCJT 299 )e loose filled bulk density and apparent densityof filter media were tested )e air-void fraction can becalculated by

v 1 minusρb

ρap

1113888 1113889 times 100 (1)

where v is the air-void faction ρb is the loose filled bulkdensity gcm3 and ρap is the apparent density gcm3

23 Filtration Test Filtration test was performed to evaluatethe capability of filter media to capture particulate matter byself-developed equipment as shown in Figure 4 )isequipment mainly contained three parts a storage bucket apump and a column )e bucket with a blender was used tosupply homogeneous pavement runoff )e pump wasequipped with a flowmeter so as to control the flow rate)ecolumn was 14 cm in diameter and 50 cm in height re-spectively Four overflow valves were designed vertically onthe column with an interval of 10 cm

In order to investigate the effect of layer thickness andgrain size of filter media on the removal efficiency of PMthree layer thickness levels of 10 cm 20 cm and 30 cm andthree grain size levels of 1ndash3mm 3ndash6mm and 6ndash8mmwere

PavementRunoff

Filter media

Infiltration tube

Figure 1 Illustration of an infiltration gutter system

2 Advances in Materials Science and Engineering

selected for each filter medium In terms of each filtrationtest the filter medium was poured into the column to adesired thickness )e constant hydraulic head of 10 cm wasmaintained throughout the test by opening the overflowvalve which was 10 cm above the top surface of the media Inorder to eliminate its effect on the filtration process flow ratewas controlled at the constant level of 4 Lmin in this studyaccording to the moderate daily rainfall in Yangzhou city[13] Effluent from the outlet of each test was collected toanalyze the TSS concentration so that the index of removalrate can be calculated by (2) for different filter media )reereplicates were conducted for each test and the averagevalues were used for analysis

η C0 minus C1

C0times 100 (2)

where C0 is the TSS concentration of influent mgL and C1is the TSS concentration of effluent mgL

24 Particle Size Distribution Test )e laser particle analyzerof Bettersize 2000 with a detection range of 001ndash800μm wasemployed to conduct the particle size distribution test Effluentfrom each filtration test was collected and the PSD of the PMwas analyzed)ree replicates were carried out for each testingsample Volume distribution curve was employed to describethe PSD of the PM)e typical diameter indices referred to asd10 d50 and d90 were chosen to determine the particle size ofthe PM )e d50 index represents the median diameter whiled10 and d90 mean the tenth and ninetieth percentile diameterrespectively Furthermore the particle size range was dividedinto six intervals namely 0ndash1μm 1ndash9μm 9ndash49μm49ndash161μm 161ndash417μm and 417ndash800μm to determine thePSD changes in greater detail according to the PSD result ofthe PM in each sample

25 Clogging Test )e particulate matter captured by filtermedia leads to deterioration in hydraulic conductivity As a

Filtration testRaw materials and equipment

Long-term clogging testAnalysis and discussion

Synthetic runoff preparationFilter media selectionSelf-developed filtration testequipment

(i)(ii)

(iii)

Evaluation of the PM capture capability of filter mediaLayer thickness and grain size of filter mediaChanges in PM removal rateChanges in PSD of PM in runoff

(i)(ii)

(iii)

Evaluation of clogging characteristics of filter mediaChanges in hydraulic conductivity over timeChanges in pollutant removal rates over timeClogging stage determination

(i)(ii)

(iii)

Particle sizes of PM causing cloggingPM capture capability ampclogging resistanceOptimum maintenance timing

(i)(ii)

(iii)

Figure 2 Illustration of research plan

Table 1 Pollutant characteristics of synthetic pavement runoff

Types of pollutants TSS COD TN TP Zn PbTarget concentration (mgL) 300 250 10 15 50 20Substance Road-deposited dust C6H12O6 NH4Cl KH2PO4 Zn (NO3)2 Pb (NO3)2Test methods GBT 11914 GBT 11901 HJ 636 GBT 11893 GB 7475 GB 7475

5mm

20μm

(a) (b) (c) (d) (e)

Figure 3 Surface morphologies and microstructures of the selected filter media (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite (e)Vesuvianite

Advances in Materials Science and Engineering 3

result the clogging characteristics of filter media can bedetermined by monitoring the changes in hydraulic con-ductivity as clogging develops)e hydraulic conductivity ofeach filter medium was measured by constant hydraulichead method using the same equipment as the filtration test(Figure 4) )e filter medium was firstly poured into thecolumn to a desired thickness and soaked in deionized waterfor one hour to saturated status )en the valve was openedand the water kept flowing though the filter medium Whenthe hydraulic head and effluent rate were stable the totalvolume of the influent through the filter media was recordedwithin a certain period of time )e hydraulic conductivitycan be calculated by

K QL

AΔhttimes 10 (3)

where K is the hydraulic conductivity mms Q is the totalvolume of the influent within t seconds cm3 L is thethickness of filter media cm A is the active cross-sectionalarea of filter media cm2 Δh is the hydraulic head cm and t

is the filtration time s)e long-term clogging process was simulated by con-

trolling the gross amount of the particulate matter which wascalculated based on the annual volume and TSS concentrationsof pavement runoff in Yangzhou city when the dry seasoneffect on clogging process was not considered In this test oneyear was taken as one simulation period and 8 periods wereconducted since at the end of 8 years simulation running thehydraulic conductivity of each filter medium has reduced toless than 40 of the original value indicating that the filermedia lost the required functions At the end of each simulationperiod (one year) the hydraulic conductivity was measuredSubsequently the retained ratio of hydraulic conductivity(RRHC)was defined to evaluate the clogging degree whichwasexpressed by (4) Besides the pollutantsrsquo concentrations in theeffluent were tested and the resultant removal rate of eachpollutant was calculated according to (2)

φ Ksj

Ki

times 100 (4)

where φ is the retained ratio of hydraulic conductivity Ksj is the hydraulic conductivity at simulation period jj 12345678 mms and Ki is the initial hydraulicconductivity mms

3 Results and Discussion

31 Particle Removal Efficiency of Different Filter Media

311 Effect of Layer 3ickness of Filter Media )ree layerthickness levels of 10 cm 20 cm and 30 cm were preparedfor each filter medium to study the effect of layer thicknesson the particle removal efficiency )e grain size of 3ndash6mmwas selected in this test for each filter medium since thisgrain size is the most used one )e removal rate of TSS andthe particle size distribution were used to evaluate theparticle removal efficiency so as to assess the size ranges ofthe particulate matter captured by the filter media during thefiltration process )e results of removal rate and PSD fromeach filter medium are illustrated in Figure 5

)e effect of layer thickness of Zeolite on the particleremoval efficiency is shown in Figures 5(a) and 5(b) It canbe seen that the removal rate of TSS increased from 694 to790 as the layer thickness increased from 10 cm to 20 cmHowever the removal rate remained at the same level whenthe layer thickness further increased from 20 cm to 30 cmObvious PSD variations could also be observed corre-spondingly In terms of the original influent the particle sizeof PM was distributed mainly within the intervals of49ndash161 μm 161ndash417 μm and 417ndash800 μm which accountedfor 322 428 and 87 of the total particles respectivelyAs for the effluent runoff through Zeolite 100 of theparticles with the size range of 417ndash800 μmwere captured byZeolite and only a small proportion (33) of PM with the

PumpFlowmeter

Overflow valve

Filter media

Outlet

Blender

Storage bucket

(a)

Sampling bottlesOutlet

Filter media

Overflow valve

Nozzle

Flow meter

Pump

Blender

Storage bucket

(b)

Figure 4 Schematic of filtration test equipment (a) Diagram of the equipment (b) Picture view

4 Advances in Materials Science and Engineering

Removal rateRetained rate

811

79

694

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(a)

0-1μm1ndash9μm9ndash49μm

Vol

ume f

ract

ion

()

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm0

20

40

60

80

100

30cm

(b)

Removal rateRetained rate

927

858

736

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

803

798

71

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 5 Continued

Advances in Materials Science and Engineering 5

size range of 161ndash417 μm could be observed when the layerthickness was 10 cm while almost none of these size rangesof particles could be seen when the thickness increased to20 cm It means that Zeolite can remove the particulatematter with the size range of over 161 μm effectively evenwith the layer thickness of 10 cm In addition with an in-creasing layer thickness the proportions of particles with thesize range of 49ndash161 μm decreased gradually Consideringthe similar removal efficiency between the thickness of 20 cmand 30 cm the thickness of 20 cm is suitable enough forZeolite to remove PM

)e effect of layer thickness of Ceramsite on theparticle removal efficiency is illustrated in Figures 5(c)and 5(d) It can be seen that the removal rate of TSS

increased from 736 to 858 when the layer thicknessincreased from 10 cm to 20 cm and it further increased to927 with the layer thickness of 30 cm As for the effluentrunoff through the Ceramsite 39 of PM with the sizerange of 417ndash800 μm and a big proportion (288) of PMwith the size range of 161ndash417 μm could be observed whenthe layer thickness was 10 cm )e 161ndash417 μm fraction ofPM reduced sharply to 29 only when the thicknessincreased to 20 cm along with the 49ndash161 μm fraction ofPM decreasing significantly from 411 to 207 It meansthat 10 cm thickness of Ceramsite presents inferior ca-pability to remove the PM with the size range of over161 μm and 20 cm thickness of Ceramsite shows satis-factory capability to capture the particles

826

728

528

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

86

845

645

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 5 Effect of layer thickness on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite)(i) TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

6 Advances in Materials Science and Engineering

)e effect of layer thickness of Slag on the particle re-moval efficiency is shown in Figures 5(e) and 5(f) Com-paratively Slag presented particle removal characteristicssimilar to those of Zeolite )e removal rate of TSS for theSlag with each layer thickness was close As for the effluentrunoff through Slag the 161ndash417 μm fraction and 49ndash161 μmfraction of PM decreased significantly as the layer thicknessincreased from 10 cm to 30 cm However Slag showed in-ferior capability to capture the PM with the range over161 μm compared to Zeolite

)e effect of layer thickness of Diatomite on the particleremoval efficiency is presented in Figures 5(g) and 5(h) Itcan be seen that the removal rate of TSS was as insufficient as528 when the layer thickness was 10 cm )e removal rateof TSS increased to 728 and 826 which was comparableto that of Zeolite and Slag when the layer thickness in-creased to 20 cm and 30 cm As for the effluent runoffthrough the Diatomite none of the PMwith the size range of417ndash800 μm and a tiny proportion (22) of PMwith the sizerange of 161ndash417 μm could be observed when the layerthickness was 10 cm despite the low removal rate Un-doubtedly the 49ndash161 μm fraction of PM also decreasedgreatly as the layer thickness increased from 10 cm to 30 cm)is indicates that Diatomite possesses unique capability tocapture the PM with the size range of over 161 μm

)e effect of layer thickness of Vesuvianite on theparticle removal efficiency is illustrated in Figures 5(i) and5(j) It can be seen that the removal rate of TSS increasedgreatly from 645 to 845 as the layer thickness increasedfrom 10 cm to 20 cm However the removal rate remained atthe same level when the layer thickness increased from 20 to30 cm As for the effluent runoff through the Vesuvianite thePSD presented similar trends to that of Diatomite When thelayer thickness was 10 cm none of the PM with fraction of417ndash800 μm and a tiny proportion (24) of PMwith the sizerange of 161ndash417 μm could be observed Moreover all of the49ndash161 μm fractions of PM were captured by Vesuvianitewhen the layer thickness reached 30 cm

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 2 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased sharply )is implies thatall the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices decreased with an increasing layer thickness It isnoticeable that when the layer thickness was 10 cm the d50and d90 of effluent from Ceramsite and Slag were muchbigger than those of the other three filter media but thediameter indices became comparable when the layerthickness increased to 20 cm Effluent from Vesuvianitepresented the smallest diameter indices indicating that itpossesses superior capability to capture particles

Overall different filter media showed great differences inparticle removal characteristics also impacted significantlyby the layer thickness When the layer thickness was 10 cmCeramsite presented a higher removal rate but the fractionover 161 μm of PM could not be captured effectively whileDiatomite and Vesuvianite presented the opposite trends)is indicates that both of the particle capture capability and

the removal rate should be considered for filter media se-lection When the layer thickness reached 20 cm all the fivefilter media showed satisfactory particle removal efficiencyand Vesuvianite presented the highest removal rate and thebest capability to capture coarse particles

312 Effect of Grain Size of Filter Media )ree grain sizelevels of 1ndash3mm 3ndash6mm and 6ndash8mm were prepared foreach filter medium to investigate the effect of grain size onthe particle removal efficiency According to the layerthickness test results 20 cm was selected for each filtermedium in this test Similarly the removal rate of TSS andthe particle size distribution were used to evaluate theparticle removal efficiency )e results of TSS removal rateand PSD from each filter medium are illustrated in Figure 6

)e effect of grain size of Zeolite on the particle removalefficiency is shown in Figures 6(a) and 6(b) It can be seenthat the grain size had a considerable impact on the removalrate )e removal rate of TSS decreased from 891 to 790as the grain size increased from 1ndash3mm to 3ndash6mm and itfurther reduced to 694 as the grain size increased to6ndash8mm Meanwhile PSD variations could also be observedAs for the effluent runoff through Zeolite almost none of thePM with the size range of over 161 μm was observedHowever the 49ndash161 μm fraction of PM presented a re-markable increase as the grain size increased from 1ndash3mmto 3ndash6mm or 6ndash8mm )is means that all grain sizes ofZeolite can capture the particles with the size range of over161 μm effectively but Zeolite with the grain size of 1ndash3mmpossesses superior particle removal capability

)e effect of grain size of Ceramsite on the particleremoval efficiency is illustrated in Figures 6(c) and 6(d) Itcan be seen that the removal rate of TSS remained at thesame level for Ceramsite with the grain size of 1ndash3mm and3ndash6mm However a big drop in the removal rate could beobserved when Ceramsite with the grain size of 6ndash8mm wasused As for the effluent runoff through Ceramsite none ofthe 161ndash800 μm fractions of PM could be observed whenCeramsite with grain size of 1ndash3mmwas used Neverthelessthere was no big difference in the PSD for Ceramsite withgrain size of 3ndash6mm or 6ndash8mm )e 49ndash161 μm fraction ofPM increased greatly and the 161ndash417 μm fraction of PMcould be observed when Ceramsite with the grain size of3ndash6mm and 6ndash8mmwas used)is indicates that Ceramsitewith the grain size of 1ndash3mm has superior capability toremove coarse particles

)e effect of grain size of Slag on the particle removalefficiency is shown in Figures 6(e) and 6(f) It can be seenthat the grain size did impact the removal rate greatly )eremoval rate of TSS reached as high as 977 when the grainsize of 1ndash3mm was used )en it reduced sharply to 798and 627 as the grain size increased to 3ndash6mm and6ndash8mm PSD variations also changed subsequently As forthe effluent runoff through Slag when the grain size of1ndash3mm was used the 1ndash9 μm and 9ndash49 μm fractions of PMaccounted for 895 of the total particles When the grainsize of 3ndash6mm or 6ndash8mm was used a small proportion of161ndash417 μm fraction of PM could be observed while the

Advances in Materials Science and Engineering 7

49ndash161 μm fraction of PM grew to 199 and 220 re-spectively )is implies that Slag grain sizes of 3ndash6mm and6ndash8mm have equivalent capability to capture particles

)e effect of grain size of Diatomite on the particleremoval efficiency is presented in Figures 6(g) and 6(h) Itcan be seen that the removal rate of TSS remained at thesame level of around 728ndash754 for Diatomite with thegrain size of 1ndash3mm and 3ndash6mm However the removalrate reduced to 573 when Diatomite with the grain size of6ndash8mm was used Meanwhile PSD results did not showobvious variations As for the effluent runoff through Di-atomite none of the PM with the size range of over 161 μmcould be seen )e 1ndash9 μm 9ndash49 μm and 49ndash161 μm frac-tions of PM were close for Diatomite with all the three grainsizes )is indicates that Diatomite possesses excellent ca-pability to capture the particles with the size range of over161 μm despite the differences in grain size

)e effect of grain size of Vesuvianite on the particleremoval efficiency is illustrated in Figures 6(i) and 6(j) It canbe seen that the grain size had a remarkable influence on theremoval rate)e removal rate of TSS reduced from 972 to845 as the grain size increased from 1ndash3mm to 3ndash6mmand it further reduced to 728 as the grain size increased to6ndash8mm As for the effluent runoff through Vesuvianitethere was no big difference in the PSD for the filter mediumwith grain size of 1ndash3mm or 3ndash6mm However the49ndash161 μm fraction of PM increased significantly from 8 to463 when the grain size of 6ndash8mm was used )is in-dicates that Vesuvianite with the grain size of 6ndash8mm hasinferior capability to remove the 49ndash161 μm fraction of PM

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 3 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased dramatically )is impliesthat all the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices grew with an increasing grain size It is noticeablethat when the grain size of 6ndash8mm was used the d50 ofeffluent from Vesuvianite was much bigger than those fromother filter media Meanwhile the d90 of effluent fromCeramsite and Slag was much bigger than those of otherfilter media All the three diameter indices would not be-come comparable only when the grain size of 1ndash3mm wasused for each filter medium

Overall the grain size of filter media did impact theparticle removal efficiency significantly Generally the finerthe grain size is the higher the removal efficiency will bealthough Diatomite with each grain size could capture thecoarse particles effectively All the filter media with the grainsize of 1-3mm presented comparably superior capability to

capture particles but only Slag and Vesuvianite showedremoval rate as high as over 90 When the grain size of3ndash6mm was used accepted removal efficiency could beachieved for each filter medium and Vesuvianite alsopresented both the highest removal rate and the best ca-pability to capture coarse particles When the grain size of6ndash8mm was used Ceramsite and Slag showed inferior re-moval efficiency of PM with the size range of over 161 μm

32 Clogging Resistance of Different Filter Media

321 Initial Hydraulic Conductivity of Filter Media )e air-void fractions and initial hydraulic conductivity of the fivetypes of filter media with three grain size levels were testedand the results are illustrated in Figure 7

It can be seen from Figure 7 that the grain size presentedlimited impact on the air-void fractions for each filtermedium though a small increase could be observed with theincrease in grain size )e air-void fractions of Diatomiteand Vesuvianite reached relatively high values of 62 and60 respectively while air-void fractions of ZeoliteCeramsite and Slag remained at the levels of 45ndash50 Asfor the initial hydraulic conductivity just a slight growthcould be observed as the grain size increased Ceramsitepresented much higher hydraulic conductivity of around63mms while hydraulic conductivity was around 45mmsfor Zeolite and Diatomite and around 50mms for Slag andVesuvianite )is indicates that hydraulic conductivity maydepend on not only the air-void fractions but also the mi-crostructure of filter media Ceramsite possesses some parts ofsmooth surface in micro texture (Figure 3(b)) which canaccelerate the flow rate leading to the high hydraulicconductivity

322 Long-Term Clogging Characteristics of Different FilterMedia According to the results in Section 31 the layerthickness and grain size had significant impact on theparticle removal efficiency For comparison study each filtermedium with the same layer thickness of 20 cm and grainsize of 3ndash6mm was selected for this clogging test )eretained ratio of hydraulic conductivity φ and the removalrates of pollutants are plotted against simulation time inFigure 8

It can be seen from Figure 8 that the hydraulic con-ductivity presented roughly a downward trend over simu-lation time For all filter media retained ratio of hydraulicconductivity φ decreased rapidly at the first 3-4 years in-dicating a fast clogging stage )en φ remained stable oreven recovered a little bit for the next 1-2 years indicating a

Table 2 Typical diameter indices of runoff through filter media with different layer thickness

Index(μm)

Influentrunoff

Zeolite Ceramsite Slag Diatomite Vesuvianite10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm

D10 523 211 176 155 881 211 197 317 222 177 263 198 186 220 183 145D50 1936 158 952 951 1069 129 105 445 158 691 196 111 96 164 902 528D90 4007 1028 640 539 3105 957 517 1752 1179 4724 889 673 526 985 478 183

8 Advances in Materials Science and Engineering

Removal rateRetained rate

694

79

891

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(a)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(b)

Removal rateRetained rate

728

858

899

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

627

798

977

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 6 Continued

Advances in Materials Science and Engineering 9

stable clogging stage Afterwards φ showed a slow decliningtrend for the remaining simulation periods indicating agradual clogging stage At the end of the 8-year simulation φwas only 35 26 31 19 and 39 for Zeolite

Ceramsite Slag Diatomite and Vesuvianite respectively)is implies that Vesuvianite possesses superior cloggingresistant property while Diatomite is more prone toclogging

Table 3 Typical diameter indices of runoff through filter media with different layer thickness

Index (μm) Influent runoffZeolite Ceramsite Slag Diatomite Vesuvianite

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8D10 523 163 176 227 188 211 261 153 222 253 190 198 224 169 183 356D50 1936 666 952 125 837 129 220 64 158 164 954 111 140 773 902 455D90 4007 334 640 775 575 957 1360 323 1179 1272 533 673 725 432 478 940

Removal rateRetained rate

573

728

754

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

Removal rateRetained rate

728

845

972

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 6 Effect of grain size on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite) (i)TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

10 Advances in Materials Science and Engineering

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

selected for each filter medium In terms of each filtrationtest the filter medium was poured into the column to adesired thickness )e constant hydraulic head of 10 cm wasmaintained throughout the test by opening the overflowvalve which was 10 cm above the top surface of the media Inorder to eliminate its effect on the filtration process flow ratewas controlled at the constant level of 4 Lmin in this studyaccording to the moderate daily rainfall in Yangzhou city[13] Effluent from the outlet of each test was collected toanalyze the TSS concentration so that the index of removalrate can be calculated by (2) for different filter media )reereplicates were conducted for each test and the averagevalues were used for analysis

η C0 minus C1

C0times 100 (2)

where C0 is the TSS concentration of influent mgL and C1is the TSS concentration of effluent mgL

24 Particle Size Distribution Test )e laser particle analyzerof Bettersize 2000 with a detection range of 001ndash800μm wasemployed to conduct the particle size distribution test Effluentfrom each filtration test was collected and the PSD of the PMwas analyzed)ree replicates were carried out for each testingsample Volume distribution curve was employed to describethe PSD of the PM)e typical diameter indices referred to asd10 d50 and d90 were chosen to determine the particle size ofthe PM )e d50 index represents the median diameter whiled10 and d90 mean the tenth and ninetieth percentile diameterrespectively Furthermore the particle size range was dividedinto six intervals namely 0ndash1μm 1ndash9μm 9ndash49μm49ndash161μm 161ndash417μm and 417ndash800μm to determine thePSD changes in greater detail according to the PSD result ofthe PM in each sample

25 Clogging Test )e particulate matter captured by filtermedia leads to deterioration in hydraulic conductivity As a

Filtration testRaw materials and equipment

Long-term clogging testAnalysis and discussion

Synthetic runoff preparationFilter media selectionSelf-developed filtration testequipment

(i)(ii)

(iii)

Evaluation of the PM capture capability of filter mediaLayer thickness and grain size of filter mediaChanges in PM removal rateChanges in PSD of PM in runoff

(i)(ii)

(iii)

Evaluation of clogging characteristics of filter mediaChanges in hydraulic conductivity over timeChanges in pollutant removal rates over timeClogging stage determination

(i)(ii)

(iii)

Particle sizes of PM causing cloggingPM capture capability ampclogging resistanceOptimum maintenance timing

(i)(ii)

(iii)

Figure 2 Illustration of research plan

Table 1 Pollutant characteristics of synthetic pavement runoff

Types of pollutants TSS COD TN TP Zn PbTarget concentration (mgL) 300 250 10 15 50 20Substance Road-deposited dust C6H12O6 NH4Cl KH2PO4 Zn (NO3)2 Pb (NO3)2Test methods GBT 11914 GBT 11901 HJ 636 GBT 11893 GB 7475 GB 7475

5mm

20μm

(a) (b) (c) (d) (e)

Figure 3 Surface morphologies and microstructures of the selected filter media (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite (e)Vesuvianite

Advances in Materials Science and Engineering 3

result the clogging characteristics of filter media can bedetermined by monitoring the changes in hydraulic con-ductivity as clogging develops)e hydraulic conductivity ofeach filter medium was measured by constant hydraulichead method using the same equipment as the filtration test(Figure 4) )e filter medium was firstly poured into thecolumn to a desired thickness and soaked in deionized waterfor one hour to saturated status )en the valve was openedand the water kept flowing though the filter medium Whenthe hydraulic head and effluent rate were stable the totalvolume of the influent through the filter media was recordedwithin a certain period of time )e hydraulic conductivitycan be calculated by

K QL

AΔhttimes 10 (3)

where K is the hydraulic conductivity mms Q is the totalvolume of the influent within t seconds cm3 L is thethickness of filter media cm A is the active cross-sectionalarea of filter media cm2 Δh is the hydraulic head cm and t

is the filtration time s)e long-term clogging process was simulated by con-

trolling the gross amount of the particulate matter which wascalculated based on the annual volume and TSS concentrationsof pavement runoff in Yangzhou city when the dry seasoneffect on clogging process was not considered In this test oneyear was taken as one simulation period and 8 periods wereconducted since at the end of 8 years simulation running thehydraulic conductivity of each filter medium has reduced toless than 40 of the original value indicating that the filermedia lost the required functions At the end of each simulationperiod (one year) the hydraulic conductivity was measuredSubsequently the retained ratio of hydraulic conductivity(RRHC)was defined to evaluate the clogging degree whichwasexpressed by (4) Besides the pollutantsrsquo concentrations in theeffluent were tested and the resultant removal rate of eachpollutant was calculated according to (2)

φ Ksj

Ki

times 100 (4)

where φ is the retained ratio of hydraulic conductivity Ksj is the hydraulic conductivity at simulation period jj 12345678 mms and Ki is the initial hydraulicconductivity mms

3 Results and Discussion

31 Particle Removal Efficiency of Different Filter Media

311 Effect of Layer 3ickness of Filter Media )ree layerthickness levels of 10 cm 20 cm and 30 cm were preparedfor each filter medium to study the effect of layer thicknesson the particle removal efficiency )e grain size of 3ndash6mmwas selected in this test for each filter medium since thisgrain size is the most used one )e removal rate of TSS andthe particle size distribution were used to evaluate theparticle removal efficiency so as to assess the size ranges ofthe particulate matter captured by the filter media during thefiltration process )e results of removal rate and PSD fromeach filter medium are illustrated in Figure 5

)e effect of layer thickness of Zeolite on the particleremoval efficiency is shown in Figures 5(a) and 5(b) It canbe seen that the removal rate of TSS increased from 694 to790 as the layer thickness increased from 10 cm to 20 cmHowever the removal rate remained at the same level whenthe layer thickness further increased from 20 cm to 30 cmObvious PSD variations could also be observed corre-spondingly In terms of the original influent the particle sizeof PM was distributed mainly within the intervals of49ndash161 μm 161ndash417 μm and 417ndash800 μm which accountedfor 322 428 and 87 of the total particles respectivelyAs for the effluent runoff through Zeolite 100 of theparticles with the size range of 417ndash800 μmwere captured byZeolite and only a small proportion (33) of PM with the

PumpFlowmeter

Overflow valve

Filter media

Outlet

Blender

Storage bucket

(a)

Sampling bottlesOutlet

Filter media

Overflow valve

Nozzle

Flow meter

Pump

Blender

Storage bucket

(b)

Figure 4 Schematic of filtration test equipment (a) Diagram of the equipment (b) Picture view

4 Advances in Materials Science and Engineering

Removal rateRetained rate

811

79

694

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(a)

0-1μm1ndash9μm9ndash49μm

Vol

ume f

ract

ion

()

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm0

20

40

60

80

100

30cm

(b)

Removal rateRetained rate

927

858

736

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

803

798

71

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 5 Continued

Advances in Materials Science and Engineering 5

size range of 161ndash417 μm could be observed when the layerthickness was 10 cm while almost none of these size rangesof particles could be seen when the thickness increased to20 cm It means that Zeolite can remove the particulatematter with the size range of over 161 μm effectively evenwith the layer thickness of 10 cm In addition with an in-creasing layer thickness the proportions of particles with thesize range of 49ndash161 μm decreased gradually Consideringthe similar removal efficiency between the thickness of 20 cmand 30 cm the thickness of 20 cm is suitable enough forZeolite to remove PM

)e effect of layer thickness of Ceramsite on theparticle removal efficiency is illustrated in Figures 5(c)and 5(d) It can be seen that the removal rate of TSS

increased from 736 to 858 when the layer thicknessincreased from 10 cm to 20 cm and it further increased to927 with the layer thickness of 30 cm As for the effluentrunoff through the Ceramsite 39 of PM with the sizerange of 417ndash800 μm and a big proportion (288) of PMwith the size range of 161ndash417 μm could be observed whenthe layer thickness was 10 cm )e 161ndash417 μm fraction ofPM reduced sharply to 29 only when the thicknessincreased to 20 cm along with the 49ndash161 μm fraction ofPM decreasing significantly from 411 to 207 It meansthat 10 cm thickness of Ceramsite presents inferior ca-pability to remove the PM with the size range of over161 μm and 20 cm thickness of Ceramsite shows satis-factory capability to capture the particles

826

728

528

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

86

845

645

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 5 Effect of layer thickness on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite)(i) TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

6 Advances in Materials Science and Engineering

)e effect of layer thickness of Slag on the particle re-moval efficiency is shown in Figures 5(e) and 5(f) Com-paratively Slag presented particle removal characteristicssimilar to those of Zeolite )e removal rate of TSS for theSlag with each layer thickness was close As for the effluentrunoff through Slag the 161ndash417 μm fraction and 49ndash161 μmfraction of PM decreased significantly as the layer thicknessincreased from 10 cm to 30 cm However Slag showed in-ferior capability to capture the PM with the range over161 μm compared to Zeolite

)e effect of layer thickness of Diatomite on the particleremoval efficiency is presented in Figures 5(g) and 5(h) Itcan be seen that the removal rate of TSS was as insufficient as528 when the layer thickness was 10 cm )e removal rateof TSS increased to 728 and 826 which was comparableto that of Zeolite and Slag when the layer thickness in-creased to 20 cm and 30 cm As for the effluent runoffthrough the Diatomite none of the PMwith the size range of417ndash800 μm and a tiny proportion (22) of PMwith the sizerange of 161ndash417 μm could be observed when the layerthickness was 10 cm despite the low removal rate Un-doubtedly the 49ndash161 μm fraction of PM also decreasedgreatly as the layer thickness increased from 10 cm to 30 cm)is indicates that Diatomite possesses unique capability tocapture the PM with the size range of over 161 μm

)e effect of layer thickness of Vesuvianite on theparticle removal efficiency is illustrated in Figures 5(i) and5(j) It can be seen that the removal rate of TSS increasedgreatly from 645 to 845 as the layer thickness increasedfrom 10 cm to 20 cm However the removal rate remained atthe same level when the layer thickness increased from 20 to30 cm As for the effluent runoff through the Vesuvianite thePSD presented similar trends to that of Diatomite When thelayer thickness was 10 cm none of the PM with fraction of417ndash800 μm and a tiny proportion (24) of PMwith the sizerange of 161ndash417 μm could be observed Moreover all of the49ndash161 μm fractions of PM were captured by Vesuvianitewhen the layer thickness reached 30 cm

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 2 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased sharply )is implies thatall the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices decreased with an increasing layer thickness It isnoticeable that when the layer thickness was 10 cm the d50and d90 of effluent from Ceramsite and Slag were muchbigger than those of the other three filter media but thediameter indices became comparable when the layerthickness increased to 20 cm Effluent from Vesuvianitepresented the smallest diameter indices indicating that itpossesses superior capability to capture particles

Overall different filter media showed great differences inparticle removal characteristics also impacted significantlyby the layer thickness When the layer thickness was 10 cmCeramsite presented a higher removal rate but the fractionover 161 μm of PM could not be captured effectively whileDiatomite and Vesuvianite presented the opposite trends)is indicates that both of the particle capture capability and

the removal rate should be considered for filter media se-lection When the layer thickness reached 20 cm all the fivefilter media showed satisfactory particle removal efficiencyand Vesuvianite presented the highest removal rate and thebest capability to capture coarse particles

312 Effect of Grain Size of Filter Media )ree grain sizelevels of 1ndash3mm 3ndash6mm and 6ndash8mm were prepared foreach filter medium to investigate the effect of grain size onthe particle removal efficiency According to the layerthickness test results 20 cm was selected for each filtermedium in this test Similarly the removal rate of TSS andthe particle size distribution were used to evaluate theparticle removal efficiency )e results of TSS removal rateand PSD from each filter medium are illustrated in Figure 6

)e effect of grain size of Zeolite on the particle removalefficiency is shown in Figures 6(a) and 6(b) It can be seenthat the grain size had a considerable impact on the removalrate )e removal rate of TSS decreased from 891 to 790as the grain size increased from 1ndash3mm to 3ndash6mm and itfurther reduced to 694 as the grain size increased to6ndash8mm Meanwhile PSD variations could also be observedAs for the effluent runoff through Zeolite almost none of thePM with the size range of over 161 μm was observedHowever the 49ndash161 μm fraction of PM presented a re-markable increase as the grain size increased from 1ndash3mmto 3ndash6mm or 6ndash8mm )is means that all grain sizes ofZeolite can capture the particles with the size range of over161 μm effectively but Zeolite with the grain size of 1ndash3mmpossesses superior particle removal capability

)e effect of grain size of Ceramsite on the particleremoval efficiency is illustrated in Figures 6(c) and 6(d) Itcan be seen that the removal rate of TSS remained at thesame level for Ceramsite with the grain size of 1ndash3mm and3ndash6mm However a big drop in the removal rate could beobserved when Ceramsite with the grain size of 6ndash8mm wasused As for the effluent runoff through Ceramsite none ofthe 161ndash800 μm fractions of PM could be observed whenCeramsite with grain size of 1ndash3mmwas used Neverthelessthere was no big difference in the PSD for Ceramsite withgrain size of 3ndash6mm or 6ndash8mm )e 49ndash161 μm fraction ofPM increased greatly and the 161ndash417 μm fraction of PMcould be observed when Ceramsite with the grain size of3ndash6mm and 6ndash8mmwas used)is indicates that Ceramsitewith the grain size of 1ndash3mm has superior capability toremove coarse particles

)e effect of grain size of Slag on the particle removalefficiency is shown in Figures 6(e) and 6(f) It can be seenthat the grain size did impact the removal rate greatly )eremoval rate of TSS reached as high as 977 when the grainsize of 1ndash3mm was used )en it reduced sharply to 798and 627 as the grain size increased to 3ndash6mm and6ndash8mm PSD variations also changed subsequently As forthe effluent runoff through Slag when the grain size of1ndash3mm was used the 1ndash9 μm and 9ndash49 μm fractions of PMaccounted for 895 of the total particles When the grainsize of 3ndash6mm or 6ndash8mm was used a small proportion of161ndash417 μm fraction of PM could be observed while the

Advances in Materials Science and Engineering 7

49ndash161 μm fraction of PM grew to 199 and 220 re-spectively )is implies that Slag grain sizes of 3ndash6mm and6ndash8mm have equivalent capability to capture particles

)e effect of grain size of Diatomite on the particleremoval efficiency is presented in Figures 6(g) and 6(h) Itcan be seen that the removal rate of TSS remained at thesame level of around 728ndash754 for Diatomite with thegrain size of 1ndash3mm and 3ndash6mm However the removalrate reduced to 573 when Diatomite with the grain size of6ndash8mm was used Meanwhile PSD results did not showobvious variations As for the effluent runoff through Di-atomite none of the PM with the size range of over 161 μmcould be seen )e 1ndash9 μm 9ndash49 μm and 49ndash161 μm frac-tions of PM were close for Diatomite with all the three grainsizes )is indicates that Diatomite possesses excellent ca-pability to capture the particles with the size range of over161 μm despite the differences in grain size

)e effect of grain size of Vesuvianite on the particleremoval efficiency is illustrated in Figures 6(i) and 6(j) It canbe seen that the grain size had a remarkable influence on theremoval rate)e removal rate of TSS reduced from 972 to845 as the grain size increased from 1ndash3mm to 3ndash6mmand it further reduced to 728 as the grain size increased to6ndash8mm As for the effluent runoff through Vesuvianitethere was no big difference in the PSD for the filter mediumwith grain size of 1ndash3mm or 3ndash6mm However the49ndash161 μm fraction of PM increased significantly from 8 to463 when the grain size of 6ndash8mm was used )is in-dicates that Vesuvianite with the grain size of 6ndash8mm hasinferior capability to remove the 49ndash161 μm fraction of PM

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 3 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased dramatically )is impliesthat all the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices grew with an increasing grain size It is noticeablethat when the grain size of 6ndash8mm was used the d50 ofeffluent from Vesuvianite was much bigger than those fromother filter media Meanwhile the d90 of effluent fromCeramsite and Slag was much bigger than those of otherfilter media All the three diameter indices would not be-come comparable only when the grain size of 1ndash3mm wasused for each filter medium

Overall the grain size of filter media did impact theparticle removal efficiency significantly Generally the finerthe grain size is the higher the removal efficiency will bealthough Diatomite with each grain size could capture thecoarse particles effectively All the filter media with the grainsize of 1-3mm presented comparably superior capability to

capture particles but only Slag and Vesuvianite showedremoval rate as high as over 90 When the grain size of3ndash6mm was used accepted removal efficiency could beachieved for each filter medium and Vesuvianite alsopresented both the highest removal rate and the best ca-pability to capture coarse particles When the grain size of6ndash8mm was used Ceramsite and Slag showed inferior re-moval efficiency of PM with the size range of over 161 μm

32 Clogging Resistance of Different Filter Media

321 Initial Hydraulic Conductivity of Filter Media )e air-void fractions and initial hydraulic conductivity of the fivetypes of filter media with three grain size levels were testedand the results are illustrated in Figure 7

It can be seen from Figure 7 that the grain size presentedlimited impact on the air-void fractions for each filtermedium though a small increase could be observed with theincrease in grain size )e air-void fractions of Diatomiteand Vesuvianite reached relatively high values of 62 and60 respectively while air-void fractions of ZeoliteCeramsite and Slag remained at the levels of 45ndash50 Asfor the initial hydraulic conductivity just a slight growthcould be observed as the grain size increased Ceramsitepresented much higher hydraulic conductivity of around63mms while hydraulic conductivity was around 45mmsfor Zeolite and Diatomite and around 50mms for Slag andVesuvianite )is indicates that hydraulic conductivity maydepend on not only the air-void fractions but also the mi-crostructure of filter media Ceramsite possesses some parts ofsmooth surface in micro texture (Figure 3(b)) which canaccelerate the flow rate leading to the high hydraulicconductivity

322 Long-Term Clogging Characteristics of Different FilterMedia According to the results in Section 31 the layerthickness and grain size had significant impact on theparticle removal efficiency For comparison study each filtermedium with the same layer thickness of 20 cm and grainsize of 3ndash6mm was selected for this clogging test )eretained ratio of hydraulic conductivity φ and the removalrates of pollutants are plotted against simulation time inFigure 8

It can be seen from Figure 8 that the hydraulic con-ductivity presented roughly a downward trend over simu-lation time For all filter media retained ratio of hydraulicconductivity φ decreased rapidly at the first 3-4 years in-dicating a fast clogging stage )en φ remained stable oreven recovered a little bit for the next 1-2 years indicating a

Table 2 Typical diameter indices of runoff through filter media with different layer thickness

Index(μm)

Influentrunoff

Zeolite Ceramsite Slag Diatomite Vesuvianite10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm

D10 523 211 176 155 881 211 197 317 222 177 263 198 186 220 183 145D50 1936 158 952 951 1069 129 105 445 158 691 196 111 96 164 902 528D90 4007 1028 640 539 3105 957 517 1752 1179 4724 889 673 526 985 478 183

8 Advances in Materials Science and Engineering

Removal rateRetained rate

694

79

891

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(a)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(b)

Removal rateRetained rate

728

858

899

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

627

798

977

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 6 Continued

Advances in Materials Science and Engineering 9

stable clogging stage Afterwards φ showed a slow decliningtrend for the remaining simulation periods indicating agradual clogging stage At the end of the 8-year simulation φwas only 35 26 31 19 and 39 for Zeolite

Ceramsite Slag Diatomite and Vesuvianite respectively)is implies that Vesuvianite possesses superior cloggingresistant property while Diatomite is more prone toclogging

Table 3 Typical diameter indices of runoff through filter media with different layer thickness

Index (μm) Influent runoffZeolite Ceramsite Slag Diatomite Vesuvianite

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8D10 523 163 176 227 188 211 261 153 222 253 190 198 224 169 183 356D50 1936 666 952 125 837 129 220 64 158 164 954 111 140 773 902 455D90 4007 334 640 775 575 957 1360 323 1179 1272 533 673 725 432 478 940

Removal rateRetained rate

573

728

754

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

Removal rateRetained rate

728

845

972

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 6 Effect of grain size on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite) (i)TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

10 Advances in Materials Science and Engineering

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

result the clogging characteristics of filter media can bedetermined by monitoring the changes in hydraulic con-ductivity as clogging develops)e hydraulic conductivity ofeach filter medium was measured by constant hydraulichead method using the same equipment as the filtration test(Figure 4) )e filter medium was firstly poured into thecolumn to a desired thickness and soaked in deionized waterfor one hour to saturated status )en the valve was openedand the water kept flowing though the filter medium Whenthe hydraulic head and effluent rate were stable the totalvolume of the influent through the filter media was recordedwithin a certain period of time )e hydraulic conductivitycan be calculated by

K QL

AΔhttimes 10 (3)

where K is the hydraulic conductivity mms Q is the totalvolume of the influent within t seconds cm3 L is thethickness of filter media cm A is the active cross-sectionalarea of filter media cm2 Δh is the hydraulic head cm and t

is the filtration time s)e long-term clogging process was simulated by con-

trolling the gross amount of the particulate matter which wascalculated based on the annual volume and TSS concentrationsof pavement runoff in Yangzhou city when the dry seasoneffect on clogging process was not considered In this test oneyear was taken as one simulation period and 8 periods wereconducted since at the end of 8 years simulation running thehydraulic conductivity of each filter medium has reduced toless than 40 of the original value indicating that the filermedia lost the required functions At the end of each simulationperiod (one year) the hydraulic conductivity was measuredSubsequently the retained ratio of hydraulic conductivity(RRHC)was defined to evaluate the clogging degree whichwasexpressed by (4) Besides the pollutantsrsquo concentrations in theeffluent were tested and the resultant removal rate of eachpollutant was calculated according to (2)

φ Ksj

Ki

times 100 (4)

where φ is the retained ratio of hydraulic conductivity Ksj is the hydraulic conductivity at simulation period jj 12345678 mms and Ki is the initial hydraulicconductivity mms

3 Results and Discussion

31 Particle Removal Efficiency of Different Filter Media

311 Effect of Layer 3ickness of Filter Media )ree layerthickness levels of 10 cm 20 cm and 30 cm were preparedfor each filter medium to study the effect of layer thicknesson the particle removal efficiency )e grain size of 3ndash6mmwas selected in this test for each filter medium since thisgrain size is the most used one )e removal rate of TSS andthe particle size distribution were used to evaluate theparticle removal efficiency so as to assess the size ranges ofthe particulate matter captured by the filter media during thefiltration process )e results of removal rate and PSD fromeach filter medium are illustrated in Figure 5

)e effect of layer thickness of Zeolite on the particleremoval efficiency is shown in Figures 5(a) and 5(b) It canbe seen that the removal rate of TSS increased from 694 to790 as the layer thickness increased from 10 cm to 20 cmHowever the removal rate remained at the same level whenthe layer thickness further increased from 20 cm to 30 cmObvious PSD variations could also be observed corre-spondingly In terms of the original influent the particle sizeof PM was distributed mainly within the intervals of49ndash161 μm 161ndash417 μm and 417ndash800 μm which accountedfor 322 428 and 87 of the total particles respectivelyAs for the effluent runoff through Zeolite 100 of theparticles with the size range of 417ndash800 μmwere captured byZeolite and only a small proportion (33) of PM with the

PumpFlowmeter

Overflow valve

Filter media

Outlet

Blender

Storage bucket

(a)

Sampling bottlesOutlet

Filter media

Overflow valve

Nozzle

Flow meter

Pump

Blender

Storage bucket

(b)

Figure 4 Schematic of filtration test equipment (a) Diagram of the equipment (b) Picture view

4 Advances in Materials Science and Engineering

Removal rateRetained rate

811

79

694

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(a)

0-1μm1ndash9μm9ndash49μm

Vol

ume f

ract

ion

()

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm0

20

40

60

80

100

30cm

(b)

Removal rateRetained rate

927

858

736

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

803

798

71

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 5 Continued

Advances in Materials Science and Engineering 5

size range of 161ndash417 μm could be observed when the layerthickness was 10 cm while almost none of these size rangesof particles could be seen when the thickness increased to20 cm It means that Zeolite can remove the particulatematter with the size range of over 161 μm effectively evenwith the layer thickness of 10 cm In addition with an in-creasing layer thickness the proportions of particles with thesize range of 49ndash161 μm decreased gradually Consideringthe similar removal efficiency between the thickness of 20 cmand 30 cm the thickness of 20 cm is suitable enough forZeolite to remove PM

)e effect of layer thickness of Ceramsite on theparticle removal efficiency is illustrated in Figures 5(c)and 5(d) It can be seen that the removal rate of TSS

increased from 736 to 858 when the layer thicknessincreased from 10 cm to 20 cm and it further increased to927 with the layer thickness of 30 cm As for the effluentrunoff through the Ceramsite 39 of PM with the sizerange of 417ndash800 μm and a big proportion (288) of PMwith the size range of 161ndash417 μm could be observed whenthe layer thickness was 10 cm )e 161ndash417 μm fraction ofPM reduced sharply to 29 only when the thicknessincreased to 20 cm along with the 49ndash161 μm fraction ofPM decreasing significantly from 411 to 207 It meansthat 10 cm thickness of Ceramsite presents inferior ca-pability to remove the PM with the size range of over161 μm and 20 cm thickness of Ceramsite shows satis-factory capability to capture the particles

826

728

528

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

86

845

645

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 5 Effect of layer thickness on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite)(i) TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

6 Advances in Materials Science and Engineering

)e effect of layer thickness of Slag on the particle re-moval efficiency is shown in Figures 5(e) and 5(f) Com-paratively Slag presented particle removal characteristicssimilar to those of Zeolite )e removal rate of TSS for theSlag with each layer thickness was close As for the effluentrunoff through Slag the 161ndash417 μm fraction and 49ndash161 μmfraction of PM decreased significantly as the layer thicknessincreased from 10 cm to 30 cm However Slag showed in-ferior capability to capture the PM with the range over161 μm compared to Zeolite

)e effect of layer thickness of Diatomite on the particleremoval efficiency is presented in Figures 5(g) and 5(h) Itcan be seen that the removal rate of TSS was as insufficient as528 when the layer thickness was 10 cm )e removal rateof TSS increased to 728 and 826 which was comparableto that of Zeolite and Slag when the layer thickness in-creased to 20 cm and 30 cm As for the effluent runoffthrough the Diatomite none of the PMwith the size range of417ndash800 μm and a tiny proportion (22) of PMwith the sizerange of 161ndash417 μm could be observed when the layerthickness was 10 cm despite the low removal rate Un-doubtedly the 49ndash161 μm fraction of PM also decreasedgreatly as the layer thickness increased from 10 cm to 30 cm)is indicates that Diatomite possesses unique capability tocapture the PM with the size range of over 161 μm

)e effect of layer thickness of Vesuvianite on theparticle removal efficiency is illustrated in Figures 5(i) and5(j) It can be seen that the removal rate of TSS increasedgreatly from 645 to 845 as the layer thickness increasedfrom 10 cm to 20 cm However the removal rate remained atthe same level when the layer thickness increased from 20 to30 cm As for the effluent runoff through the Vesuvianite thePSD presented similar trends to that of Diatomite When thelayer thickness was 10 cm none of the PM with fraction of417ndash800 μm and a tiny proportion (24) of PMwith the sizerange of 161ndash417 μm could be observed Moreover all of the49ndash161 μm fractions of PM were captured by Vesuvianitewhen the layer thickness reached 30 cm

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 2 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased sharply )is implies thatall the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices decreased with an increasing layer thickness It isnoticeable that when the layer thickness was 10 cm the d50and d90 of effluent from Ceramsite and Slag were muchbigger than those of the other three filter media but thediameter indices became comparable when the layerthickness increased to 20 cm Effluent from Vesuvianitepresented the smallest diameter indices indicating that itpossesses superior capability to capture particles

Overall different filter media showed great differences inparticle removal characteristics also impacted significantlyby the layer thickness When the layer thickness was 10 cmCeramsite presented a higher removal rate but the fractionover 161 μm of PM could not be captured effectively whileDiatomite and Vesuvianite presented the opposite trends)is indicates that both of the particle capture capability and

the removal rate should be considered for filter media se-lection When the layer thickness reached 20 cm all the fivefilter media showed satisfactory particle removal efficiencyand Vesuvianite presented the highest removal rate and thebest capability to capture coarse particles

312 Effect of Grain Size of Filter Media )ree grain sizelevels of 1ndash3mm 3ndash6mm and 6ndash8mm were prepared foreach filter medium to investigate the effect of grain size onthe particle removal efficiency According to the layerthickness test results 20 cm was selected for each filtermedium in this test Similarly the removal rate of TSS andthe particle size distribution were used to evaluate theparticle removal efficiency )e results of TSS removal rateand PSD from each filter medium are illustrated in Figure 6

)e effect of grain size of Zeolite on the particle removalefficiency is shown in Figures 6(a) and 6(b) It can be seenthat the grain size had a considerable impact on the removalrate )e removal rate of TSS decreased from 891 to 790as the grain size increased from 1ndash3mm to 3ndash6mm and itfurther reduced to 694 as the grain size increased to6ndash8mm Meanwhile PSD variations could also be observedAs for the effluent runoff through Zeolite almost none of thePM with the size range of over 161 μm was observedHowever the 49ndash161 μm fraction of PM presented a re-markable increase as the grain size increased from 1ndash3mmto 3ndash6mm or 6ndash8mm )is means that all grain sizes ofZeolite can capture the particles with the size range of over161 μm effectively but Zeolite with the grain size of 1ndash3mmpossesses superior particle removal capability

)e effect of grain size of Ceramsite on the particleremoval efficiency is illustrated in Figures 6(c) and 6(d) Itcan be seen that the removal rate of TSS remained at thesame level for Ceramsite with the grain size of 1ndash3mm and3ndash6mm However a big drop in the removal rate could beobserved when Ceramsite with the grain size of 6ndash8mm wasused As for the effluent runoff through Ceramsite none ofthe 161ndash800 μm fractions of PM could be observed whenCeramsite with grain size of 1ndash3mmwas used Neverthelessthere was no big difference in the PSD for Ceramsite withgrain size of 3ndash6mm or 6ndash8mm )e 49ndash161 μm fraction ofPM increased greatly and the 161ndash417 μm fraction of PMcould be observed when Ceramsite with the grain size of3ndash6mm and 6ndash8mmwas used)is indicates that Ceramsitewith the grain size of 1ndash3mm has superior capability toremove coarse particles

)e effect of grain size of Slag on the particle removalefficiency is shown in Figures 6(e) and 6(f) It can be seenthat the grain size did impact the removal rate greatly )eremoval rate of TSS reached as high as 977 when the grainsize of 1ndash3mm was used )en it reduced sharply to 798and 627 as the grain size increased to 3ndash6mm and6ndash8mm PSD variations also changed subsequently As forthe effluent runoff through Slag when the grain size of1ndash3mm was used the 1ndash9 μm and 9ndash49 μm fractions of PMaccounted for 895 of the total particles When the grainsize of 3ndash6mm or 6ndash8mm was used a small proportion of161ndash417 μm fraction of PM could be observed while the

Advances in Materials Science and Engineering 7

49ndash161 μm fraction of PM grew to 199 and 220 re-spectively )is implies that Slag grain sizes of 3ndash6mm and6ndash8mm have equivalent capability to capture particles

)e effect of grain size of Diatomite on the particleremoval efficiency is presented in Figures 6(g) and 6(h) Itcan be seen that the removal rate of TSS remained at thesame level of around 728ndash754 for Diatomite with thegrain size of 1ndash3mm and 3ndash6mm However the removalrate reduced to 573 when Diatomite with the grain size of6ndash8mm was used Meanwhile PSD results did not showobvious variations As for the effluent runoff through Di-atomite none of the PM with the size range of over 161 μmcould be seen )e 1ndash9 μm 9ndash49 μm and 49ndash161 μm frac-tions of PM were close for Diatomite with all the three grainsizes )is indicates that Diatomite possesses excellent ca-pability to capture the particles with the size range of over161 μm despite the differences in grain size

)e effect of grain size of Vesuvianite on the particleremoval efficiency is illustrated in Figures 6(i) and 6(j) It canbe seen that the grain size had a remarkable influence on theremoval rate)e removal rate of TSS reduced from 972 to845 as the grain size increased from 1ndash3mm to 3ndash6mmand it further reduced to 728 as the grain size increased to6ndash8mm As for the effluent runoff through Vesuvianitethere was no big difference in the PSD for the filter mediumwith grain size of 1ndash3mm or 3ndash6mm However the49ndash161 μm fraction of PM increased significantly from 8 to463 when the grain size of 6ndash8mm was used )is in-dicates that Vesuvianite with the grain size of 6ndash8mm hasinferior capability to remove the 49ndash161 μm fraction of PM

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 3 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased dramatically )is impliesthat all the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices grew with an increasing grain size It is noticeablethat when the grain size of 6ndash8mm was used the d50 ofeffluent from Vesuvianite was much bigger than those fromother filter media Meanwhile the d90 of effluent fromCeramsite and Slag was much bigger than those of otherfilter media All the three diameter indices would not be-come comparable only when the grain size of 1ndash3mm wasused for each filter medium

Overall the grain size of filter media did impact theparticle removal efficiency significantly Generally the finerthe grain size is the higher the removal efficiency will bealthough Diatomite with each grain size could capture thecoarse particles effectively All the filter media with the grainsize of 1-3mm presented comparably superior capability to

capture particles but only Slag and Vesuvianite showedremoval rate as high as over 90 When the grain size of3ndash6mm was used accepted removal efficiency could beachieved for each filter medium and Vesuvianite alsopresented both the highest removal rate and the best ca-pability to capture coarse particles When the grain size of6ndash8mm was used Ceramsite and Slag showed inferior re-moval efficiency of PM with the size range of over 161 μm

32 Clogging Resistance of Different Filter Media

321 Initial Hydraulic Conductivity of Filter Media )e air-void fractions and initial hydraulic conductivity of the fivetypes of filter media with three grain size levels were testedand the results are illustrated in Figure 7

It can be seen from Figure 7 that the grain size presentedlimited impact on the air-void fractions for each filtermedium though a small increase could be observed with theincrease in grain size )e air-void fractions of Diatomiteand Vesuvianite reached relatively high values of 62 and60 respectively while air-void fractions of ZeoliteCeramsite and Slag remained at the levels of 45ndash50 Asfor the initial hydraulic conductivity just a slight growthcould be observed as the grain size increased Ceramsitepresented much higher hydraulic conductivity of around63mms while hydraulic conductivity was around 45mmsfor Zeolite and Diatomite and around 50mms for Slag andVesuvianite )is indicates that hydraulic conductivity maydepend on not only the air-void fractions but also the mi-crostructure of filter media Ceramsite possesses some parts ofsmooth surface in micro texture (Figure 3(b)) which canaccelerate the flow rate leading to the high hydraulicconductivity

322 Long-Term Clogging Characteristics of Different FilterMedia According to the results in Section 31 the layerthickness and grain size had significant impact on theparticle removal efficiency For comparison study each filtermedium with the same layer thickness of 20 cm and grainsize of 3ndash6mm was selected for this clogging test )eretained ratio of hydraulic conductivity φ and the removalrates of pollutants are plotted against simulation time inFigure 8

It can be seen from Figure 8 that the hydraulic con-ductivity presented roughly a downward trend over simu-lation time For all filter media retained ratio of hydraulicconductivity φ decreased rapidly at the first 3-4 years in-dicating a fast clogging stage )en φ remained stable oreven recovered a little bit for the next 1-2 years indicating a

Table 2 Typical diameter indices of runoff through filter media with different layer thickness

Index(μm)

Influentrunoff

Zeolite Ceramsite Slag Diatomite Vesuvianite10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm

D10 523 211 176 155 881 211 197 317 222 177 263 198 186 220 183 145D50 1936 158 952 951 1069 129 105 445 158 691 196 111 96 164 902 528D90 4007 1028 640 539 3105 957 517 1752 1179 4724 889 673 526 985 478 183

8 Advances in Materials Science and Engineering

Removal rateRetained rate

694

79

891

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(a)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(b)

Removal rateRetained rate

728

858

899

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

627

798

977

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 6 Continued

Advances in Materials Science and Engineering 9

stable clogging stage Afterwards φ showed a slow decliningtrend for the remaining simulation periods indicating agradual clogging stage At the end of the 8-year simulation φwas only 35 26 31 19 and 39 for Zeolite

Ceramsite Slag Diatomite and Vesuvianite respectively)is implies that Vesuvianite possesses superior cloggingresistant property while Diatomite is more prone toclogging

Table 3 Typical diameter indices of runoff through filter media with different layer thickness

Index (μm) Influent runoffZeolite Ceramsite Slag Diatomite Vesuvianite

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8D10 523 163 176 227 188 211 261 153 222 253 190 198 224 169 183 356D50 1936 666 952 125 837 129 220 64 158 164 954 111 140 773 902 455D90 4007 334 640 775 575 957 1360 323 1179 1272 533 673 725 432 478 940

Removal rateRetained rate

573

728

754

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

Removal rateRetained rate

728

845

972

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 6 Effect of grain size on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite) (i)TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

10 Advances in Materials Science and Engineering

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

Removal rateRetained rate

811

79

694

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(a)

0-1μm1ndash9μm9ndash49μm

Vol

ume f

ract

ion

()

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm0

20

40

60

80

100

30cm

(b)

Removal rateRetained rate

927

858

736

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

803

798

71

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 5 Continued

Advances in Materials Science and Engineering 5

size range of 161ndash417 μm could be observed when the layerthickness was 10 cm while almost none of these size rangesof particles could be seen when the thickness increased to20 cm It means that Zeolite can remove the particulatematter with the size range of over 161 μm effectively evenwith the layer thickness of 10 cm In addition with an in-creasing layer thickness the proportions of particles with thesize range of 49ndash161 μm decreased gradually Consideringthe similar removal efficiency between the thickness of 20 cmand 30 cm the thickness of 20 cm is suitable enough forZeolite to remove PM

)e effect of layer thickness of Ceramsite on theparticle removal efficiency is illustrated in Figures 5(c)and 5(d) It can be seen that the removal rate of TSS

increased from 736 to 858 when the layer thicknessincreased from 10 cm to 20 cm and it further increased to927 with the layer thickness of 30 cm As for the effluentrunoff through the Ceramsite 39 of PM with the sizerange of 417ndash800 μm and a big proportion (288) of PMwith the size range of 161ndash417 μm could be observed whenthe layer thickness was 10 cm )e 161ndash417 μm fraction ofPM reduced sharply to 29 only when the thicknessincreased to 20 cm along with the 49ndash161 μm fraction ofPM decreasing significantly from 411 to 207 It meansthat 10 cm thickness of Ceramsite presents inferior ca-pability to remove the PM with the size range of over161 μm and 20 cm thickness of Ceramsite shows satis-factory capability to capture the particles

826

728

528

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

86

845

645

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 5 Effect of layer thickness on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite)(i) TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

6 Advances in Materials Science and Engineering

)e effect of layer thickness of Slag on the particle re-moval efficiency is shown in Figures 5(e) and 5(f) Com-paratively Slag presented particle removal characteristicssimilar to those of Zeolite )e removal rate of TSS for theSlag with each layer thickness was close As for the effluentrunoff through Slag the 161ndash417 μm fraction and 49ndash161 μmfraction of PM decreased significantly as the layer thicknessincreased from 10 cm to 30 cm However Slag showed in-ferior capability to capture the PM with the range over161 μm compared to Zeolite

)e effect of layer thickness of Diatomite on the particleremoval efficiency is presented in Figures 5(g) and 5(h) Itcan be seen that the removal rate of TSS was as insufficient as528 when the layer thickness was 10 cm )e removal rateof TSS increased to 728 and 826 which was comparableto that of Zeolite and Slag when the layer thickness in-creased to 20 cm and 30 cm As for the effluent runoffthrough the Diatomite none of the PMwith the size range of417ndash800 μm and a tiny proportion (22) of PMwith the sizerange of 161ndash417 μm could be observed when the layerthickness was 10 cm despite the low removal rate Un-doubtedly the 49ndash161 μm fraction of PM also decreasedgreatly as the layer thickness increased from 10 cm to 30 cm)is indicates that Diatomite possesses unique capability tocapture the PM with the size range of over 161 μm

)e effect of layer thickness of Vesuvianite on theparticle removal efficiency is illustrated in Figures 5(i) and5(j) It can be seen that the removal rate of TSS increasedgreatly from 645 to 845 as the layer thickness increasedfrom 10 cm to 20 cm However the removal rate remained atthe same level when the layer thickness increased from 20 to30 cm As for the effluent runoff through the Vesuvianite thePSD presented similar trends to that of Diatomite When thelayer thickness was 10 cm none of the PM with fraction of417ndash800 μm and a tiny proportion (24) of PMwith the sizerange of 161ndash417 μm could be observed Moreover all of the49ndash161 μm fractions of PM were captured by Vesuvianitewhen the layer thickness reached 30 cm

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 2 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased sharply )is implies thatall the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices decreased with an increasing layer thickness It isnoticeable that when the layer thickness was 10 cm the d50and d90 of effluent from Ceramsite and Slag were muchbigger than those of the other three filter media but thediameter indices became comparable when the layerthickness increased to 20 cm Effluent from Vesuvianitepresented the smallest diameter indices indicating that itpossesses superior capability to capture particles

Overall different filter media showed great differences inparticle removal characteristics also impacted significantlyby the layer thickness When the layer thickness was 10 cmCeramsite presented a higher removal rate but the fractionover 161 μm of PM could not be captured effectively whileDiatomite and Vesuvianite presented the opposite trends)is indicates that both of the particle capture capability and

the removal rate should be considered for filter media se-lection When the layer thickness reached 20 cm all the fivefilter media showed satisfactory particle removal efficiencyand Vesuvianite presented the highest removal rate and thebest capability to capture coarse particles

312 Effect of Grain Size of Filter Media )ree grain sizelevels of 1ndash3mm 3ndash6mm and 6ndash8mm were prepared foreach filter medium to investigate the effect of grain size onthe particle removal efficiency According to the layerthickness test results 20 cm was selected for each filtermedium in this test Similarly the removal rate of TSS andthe particle size distribution were used to evaluate theparticle removal efficiency )e results of TSS removal rateand PSD from each filter medium are illustrated in Figure 6

)e effect of grain size of Zeolite on the particle removalefficiency is shown in Figures 6(a) and 6(b) It can be seenthat the grain size had a considerable impact on the removalrate )e removal rate of TSS decreased from 891 to 790as the grain size increased from 1ndash3mm to 3ndash6mm and itfurther reduced to 694 as the grain size increased to6ndash8mm Meanwhile PSD variations could also be observedAs for the effluent runoff through Zeolite almost none of thePM with the size range of over 161 μm was observedHowever the 49ndash161 μm fraction of PM presented a re-markable increase as the grain size increased from 1ndash3mmto 3ndash6mm or 6ndash8mm )is means that all grain sizes ofZeolite can capture the particles with the size range of over161 μm effectively but Zeolite with the grain size of 1ndash3mmpossesses superior particle removal capability

)e effect of grain size of Ceramsite on the particleremoval efficiency is illustrated in Figures 6(c) and 6(d) Itcan be seen that the removal rate of TSS remained at thesame level for Ceramsite with the grain size of 1ndash3mm and3ndash6mm However a big drop in the removal rate could beobserved when Ceramsite with the grain size of 6ndash8mm wasused As for the effluent runoff through Ceramsite none ofthe 161ndash800 μm fractions of PM could be observed whenCeramsite with grain size of 1ndash3mmwas used Neverthelessthere was no big difference in the PSD for Ceramsite withgrain size of 3ndash6mm or 6ndash8mm )e 49ndash161 μm fraction ofPM increased greatly and the 161ndash417 μm fraction of PMcould be observed when Ceramsite with the grain size of3ndash6mm and 6ndash8mmwas used)is indicates that Ceramsitewith the grain size of 1ndash3mm has superior capability toremove coarse particles

)e effect of grain size of Slag on the particle removalefficiency is shown in Figures 6(e) and 6(f) It can be seenthat the grain size did impact the removal rate greatly )eremoval rate of TSS reached as high as 977 when the grainsize of 1ndash3mm was used )en it reduced sharply to 798and 627 as the grain size increased to 3ndash6mm and6ndash8mm PSD variations also changed subsequently As forthe effluent runoff through Slag when the grain size of1ndash3mm was used the 1ndash9 μm and 9ndash49 μm fractions of PMaccounted for 895 of the total particles When the grainsize of 3ndash6mm or 6ndash8mm was used a small proportion of161ndash417 μm fraction of PM could be observed while the

Advances in Materials Science and Engineering 7

49ndash161 μm fraction of PM grew to 199 and 220 re-spectively )is implies that Slag grain sizes of 3ndash6mm and6ndash8mm have equivalent capability to capture particles

)e effect of grain size of Diatomite on the particleremoval efficiency is presented in Figures 6(g) and 6(h) Itcan be seen that the removal rate of TSS remained at thesame level of around 728ndash754 for Diatomite with thegrain size of 1ndash3mm and 3ndash6mm However the removalrate reduced to 573 when Diatomite with the grain size of6ndash8mm was used Meanwhile PSD results did not showobvious variations As for the effluent runoff through Di-atomite none of the PM with the size range of over 161 μmcould be seen )e 1ndash9 μm 9ndash49 μm and 49ndash161 μm frac-tions of PM were close for Diatomite with all the three grainsizes )is indicates that Diatomite possesses excellent ca-pability to capture the particles with the size range of over161 μm despite the differences in grain size

)e effect of grain size of Vesuvianite on the particleremoval efficiency is illustrated in Figures 6(i) and 6(j) It canbe seen that the grain size had a remarkable influence on theremoval rate)e removal rate of TSS reduced from 972 to845 as the grain size increased from 1ndash3mm to 3ndash6mmand it further reduced to 728 as the grain size increased to6ndash8mm As for the effluent runoff through Vesuvianitethere was no big difference in the PSD for the filter mediumwith grain size of 1ndash3mm or 3ndash6mm However the49ndash161 μm fraction of PM increased significantly from 8 to463 when the grain size of 6ndash8mm was used )is in-dicates that Vesuvianite with the grain size of 6ndash8mm hasinferior capability to remove the 49ndash161 μm fraction of PM

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 3 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased dramatically )is impliesthat all the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices grew with an increasing grain size It is noticeablethat when the grain size of 6ndash8mm was used the d50 ofeffluent from Vesuvianite was much bigger than those fromother filter media Meanwhile the d90 of effluent fromCeramsite and Slag was much bigger than those of otherfilter media All the three diameter indices would not be-come comparable only when the grain size of 1ndash3mm wasused for each filter medium

Overall the grain size of filter media did impact theparticle removal efficiency significantly Generally the finerthe grain size is the higher the removal efficiency will bealthough Diatomite with each grain size could capture thecoarse particles effectively All the filter media with the grainsize of 1-3mm presented comparably superior capability to

capture particles but only Slag and Vesuvianite showedremoval rate as high as over 90 When the grain size of3ndash6mm was used accepted removal efficiency could beachieved for each filter medium and Vesuvianite alsopresented both the highest removal rate and the best ca-pability to capture coarse particles When the grain size of6ndash8mm was used Ceramsite and Slag showed inferior re-moval efficiency of PM with the size range of over 161 μm

32 Clogging Resistance of Different Filter Media

321 Initial Hydraulic Conductivity of Filter Media )e air-void fractions and initial hydraulic conductivity of the fivetypes of filter media with three grain size levels were testedand the results are illustrated in Figure 7

It can be seen from Figure 7 that the grain size presentedlimited impact on the air-void fractions for each filtermedium though a small increase could be observed with theincrease in grain size )e air-void fractions of Diatomiteand Vesuvianite reached relatively high values of 62 and60 respectively while air-void fractions of ZeoliteCeramsite and Slag remained at the levels of 45ndash50 Asfor the initial hydraulic conductivity just a slight growthcould be observed as the grain size increased Ceramsitepresented much higher hydraulic conductivity of around63mms while hydraulic conductivity was around 45mmsfor Zeolite and Diatomite and around 50mms for Slag andVesuvianite )is indicates that hydraulic conductivity maydepend on not only the air-void fractions but also the mi-crostructure of filter media Ceramsite possesses some parts ofsmooth surface in micro texture (Figure 3(b)) which canaccelerate the flow rate leading to the high hydraulicconductivity

322 Long-Term Clogging Characteristics of Different FilterMedia According to the results in Section 31 the layerthickness and grain size had significant impact on theparticle removal efficiency For comparison study each filtermedium with the same layer thickness of 20 cm and grainsize of 3ndash6mm was selected for this clogging test )eretained ratio of hydraulic conductivity φ and the removalrates of pollutants are plotted against simulation time inFigure 8

It can be seen from Figure 8 that the hydraulic con-ductivity presented roughly a downward trend over simu-lation time For all filter media retained ratio of hydraulicconductivity φ decreased rapidly at the first 3-4 years in-dicating a fast clogging stage )en φ remained stable oreven recovered a little bit for the next 1-2 years indicating a

Table 2 Typical diameter indices of runoff through filter media with different layer thickness

Index(μm)

Influentrunoff

Zeolite Ceramsite Slag Diatomite Vesuvianite10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm

D10 523 211 176 155 881 211 197 317 222 177 263 198 186 220 183 145D50 1936 158 952 951 1069 129 105 445 158 691 196 111 96 164 902 528D90 4007 1028 640 539 3105 957 517 1752 1179 4724 889 673 526 985 478 183

8 Advances in Materials Science and Engineering

Removal rateRetained rate

694

79

891

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(a)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(b)

Removal rateRetained rate

728

858

899

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

627

798

977

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 6 Continued

Advances in Materials Science and Engineering 9

stable clogging stage Afterwards φ showed a slow decliningtrend for the remaining simulation periods indicating agradual clogging stage At the end of the 8-year simulation φwas only 35 26 31 19 and 39 for Zeolite

Ceramsite Slag Diatomite and Vesuvianite respectively)is implies that Vesuvianite possesses superior cloggingresistant property while Diatomite is more prone toclogging

Table 3 Typical diameter indices of runoff through filter media with different layer thickness

Index (μm) Influent runoffZeolite Ceramsite Slag Diatomite Vesuvianite

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8D10 523 163 176 227 188 211 261 153 222 253 190 198 224 169 183 356D50 1936 666 952 125 837 129 220 64 158 164 954 111 140 773 902 455D90 4007 334 640 775 575 957 1360 323 1179 1272 533 673 725 432 478 940

Removal rateRetained rate

573

728

754

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

Removal rateRetained rate

728

845

972

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 6 Effect of grain size on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite) (i)TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

10 Advances in Materials Science and Engineering

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

size range of 161ndash417 μm could be observed when the layerthickness was 10 cm while almost none of these size rangesof particles could be seen when the thickness increased to20 cm It means that Zeolite can remove the particulatematter with the size range of over 161 μm effectively evenwith the layer thickness of 10 cm In addition with an in-creasing layer thickness the proportions of particles with thesize range of 49ndash161 μm decreased gradually Consideringthe similar removal efficiency between the thickness of 20 cmand 30 cm the thickness of 20 cm is suitable enough forZeolite to remove PM

)e effect of layer thickness of Ceramsite on theparticle removal efficiency is illustrated in Figures 5(c)and 5(d) It can be seen that the removal rate of TSS

increased from 736 to 858 when the layer thicknessincreased from 10 cm to 20 cm and it further increased to927 with the layer thickness of 30 cm As for the effluentrunoff through the Ceramsite 39 of PM with the sizerange of 417ndash800 μm and a big proportion (288) of PMwith the size range of 161ndash417 μm could be observed whenthe layer thickness was 10 cm )e 161ndash417 μm fraction ofPM reduced sharply to 29 only when the thicknessincreased to 20 cm along with the 49ndash161 μm fraction ofPM decreasing significantly from 411 to 207 It meansthat 10 cm thickness of Ceramsite presents inferior ca-pability to remove the PM with the size range of over161 μm and 20 cm thickness of Ceramsite shows satis-factory capability to capture the particles

826

728

528

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

86

845

645

Removal rateRetained rate

20 40 60 80 1000Removal rate of TSS ()

30cm

20cm

10cm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 10cm 20cm 30cm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 5 Effect of layer thickness on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite)(i) TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

6 Advances in Materials Science and Engineering

)e effect of layer thickness of Slag on the particle re-moval efficiency is shown in Figures 5(e) and 5(f) Com-paratively Slag presented particle removal characteristicssimilar to those of Zeolite )e removal rate of TSS for theSlag with each layer thickness was close As for the effluentrunoff through Slag the 161ndash417 μm fraction and 49ndash161 μmfraction of PM decreased significantly as the layer thicknessincreased from 10 cm to 30 cm However Slag showed in-ferior capability to capture the PM with the range over161 μm compared to Zeolite

)e effect of layer thickness of Diatomite on the particleremoval efficiency is presented in Figures 5(g) and 5(h) Itcan be seen that the removal rate of TSS was as insufficient as528 when the layer thickness was 10 cm )e removal rateof TSS increased to 728 and 826 which was comparableto that of Zeolite and Slag when the layer thickness in-creased to 20 cm and 30 cm As for the effluent runoffthrough the Diatomite none of the PMwith the size range of417ndash800 μm and a tiny proportion (22) of PMwith the sizerange of 161ndash417 μm could be observed when the layerthickness was 10 cm despite the low removal rate Un-doubtedly the 49ndash161 μm fraction of PM also decreasedgreatly as the layer thickness increased from 10 cm to 30 cm)is indicates that Diatomite possesses unique capability tocapture the PM with the size range of over 161 μm

)e effect of layer thickness of Vesuvianite on theparticle removal efficiency is illustrated in Figures 5(i) and5(j) It can be seen that the removal rate of TSS increasedgreatly from 645 to 845 as the layer thickness increasedfrom 10 cm to 20 cm However the removal rate remained atthe same level when the layer thickness increased from 20 to30 cm As for the effluent runoff through the Vesuvianite thePSD presented similar trends to that of Diatomite When thelayer thickness was 10 cm none of the PM with fraction of417ndash800 μm and a tiny proportion (24) of PMwith the sizerange of 161ndash417 μm could be observed Moreover all of the49ndash161 μm fractions of PM were captured by Vesuvianitewhen the layer thickness reached 30 cm

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 2 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased sharply )is implies thatall the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices decreased with an increasing layer thickness It isnoticeable that when the layer thickness was 10 cm the d50and d90 of effluent from Ceramsite and Slag were muchbigger than those of the other three filter media but thediameter indices became comparable when the layerthickness increased to 20 cm Effluent from Vesuvianitepresented the smallest diameter indices indicating that itpossesses superior capability to capture particles

Overall different filter media showed great differences inparticle removal characteristics also impacted significantlyby the layer thickness When the layer thickness was 10 cmCeramsite presented a higher removal rate but the fractionover 161 μm of PM could not be captured effectively whileDiatomite and Vesuvianite presented the opposite trends)is indicates that both of the particle capture capability and

the removal rate should be considered for filter media se-lection When the layer thickness reached 20 cm all the fivefilter media showed satisfactory particle removal efficiencyand Vesuvianite presented the highest removal rate and thebest capability to capture coarse particles

312 Effect of Grain Size of Filter Media )ree grain sizelevels of 1ndash3mm 3ndash6mm and 6ndash8mm were prepared foreach filter medium to investigate the effect of grain size onthe particle removal efficiency According to the layerthickness test results 20 cm was selected for each filtermedium in this test Similarly the removal rate of TSS andthe particle size distribution were used to evaluate theparticle removal efficiency )e results of TSS removal rateand PSD from each filter medium are illustrated in Figure 6

)e effect of grain size of Zeolite on the particle removalefficiency is shown in Figures 6(a) and 6(b) It can be seenthat the grain size had a considerable impact on the removalrate )e removal rate of TSS decreased from 891 to 790as the grain size increased from 1ndash3mm to 3ndash6mm and itfurther reduced to 694 as the grain size increased to6ndash8mm Meanwhile PSD variations could also be observedAs for the effluent runoff through Zeolite almost none of thePM with the size range of over 161 μm was observedHowever the 49ndash161 μm fraction of PM presented a re-markable increase as the grain size increased from 1ndash3mmto 3ndash6mm or 6ndash8mm )is means that all grain sizes ofZeolite can capture the particles with the size range of over161 μm effectively but Zeolite with the grain size of 1ndash3mmpossesses superior particle removal capability

)e effect of grain size of Ceramsite on the particleremoval efficiency is illustrated in Figures 6(c) and 6(d) Itcan be seen that the removal rate of TSS remained at thesame level for Ceramsite with the grain size of 1ndash3mm and3ndash6mm However a big drop in the removal rate could beobserved when Ceramsite with the grain size of 6ndash8mm wasused As for the effluent runoff through Ceramsite none ofthe 161ndash800 μm fractions of PM could be observed whenCeramsite with grain size of 1ndash3mmwas used Neverthelessthere was no big difference in the PSD for Ceramsite withgrain size of 3ndash6mm or 6ndash8mm )e 49ndash161 μm fraction ofPM increased greatly and the 161ndash417 μm fraction of PMcould be observed when Ceramsite with the grain size of3ndash6mm and 6ndash8mmwas used)is indicates that Ceramsitewith the grain size of 1ndash3mm has superior capability toremove coarse particles

)e effect of grain size of Slag on the particle removalefficiency is shown in Figures 6(e) and 6(f) It can be seenthat the grain size did impact the removal rate greatly )eremoval rate of TSS reached as high as 977 when the grainsize of 1ndash3mm was used )en it reduced sharply to 798and 627 as the grain size increased to 3ndash6mm and6ndash8mm PSD variations also changed subsequently As forthe effluent runoff through Slag when the grain size of1ndash3mm was used the 1ndash9 μm and 9ndash49 μm fractions of PMaccounted for 895 of the total particles When the grainsize of 3ndash6mm or 6ndash8mm was used a small proportion of161ndash417 μm fraction of PM could be observed while the

Advances in Materials Science and Engineering 7

49ndash161 μm fraction of PM grew to 199 and 220 re-spectively )is implies that Slag grain sizes of 3ndash6mm and6ndash8mm have equivalent capability to capture particles

)e effect of grain size of Diatomite on the particleremoval efficiency is presented in Figures 6(g) and 6(h) Itcan be seen that the removal rate of TSS remained at thesame level of around 728ndash754 for Diatomite with thegrain size of 1ndash3mm and 3ndash6mm However the removalrate reduced to 573 when Diatomite with the grain size of6ndash8mm was used Meanwhile PSD results did not showobvious variations As for the effluent runoff through Di-atomite none of the PM with the size range of over 161 μmcould be seen )e 1ndash9 μm 9ndash49 μm and 49ndash161 μm frac-tions of PM were close for Diatomite with all the three grainsizes )is indicates that Diatomite possesses excellent ca-pability to capture the particles with the size range of over161 μm despite the differences in grain size

)e effect of grain size of Vesuvianite on the particleremoval efficiency is illustrated in Figures 6(i) and 6(j) It canbe seen that the grain size had a remarkable influence on theremoval rate)e removal rate of TSS reduced from 972 to845 as the grain size increased from 1ndash3mm to 3ndash6mmand it further reduced to 728 as the grain size increased to6ndash8mm As for the effluent runoff through Vesuvianitethere was no big difference in the PSD for the filter mediumwith grain size of 1ndash3mm or 3ndash6mm However the49ndash161 μm fraction of PM increased significantly from 8 to463 when the grain size of 6ndash8mm was used )is in-dicates that Vesuvianite with the grain size of 6ndash8mm hasinferior capability to remove the 49ndash161 μm fraction of PM

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 3 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased dramatically )is impliesthat all the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices grew with an increasing grain size It is noticeablethat when the grain size of 6ndash8mm was used the d50 ofeffluent from Vesuvianite was much bigger than those fromother filter media Meanwhile the d90 of effluent fromCeramsite and Slag was much bigger than those of otherfilter media All the three diameter indices would not be-come comparable only when the grain size of 1ndash3mm wasused for each filter medium

Overall the grain size of filter media did impact theparticle removal efficiency significantly Generally the finerthe grain size is the higher the removal efficiency will bealthough Diatomite with each grain size could capture thecoarse particles effectively All the filter media with the grainsize of 1-3mm presented comparably superior capability to

capture particles but only Slag and Vesuvianite showedremoval rate as high as over 90 When the grain size of3ndash6mm was used accepted removal efficiency could beachieved for each filter medium and Vesuvianite alsopresented both the highest removal rate and the best ca-pability to capture coarse particles When the grain size of6ndash8mm was used Ceramsite and Slag showed inferior re-moval efficiency of PM with the size range of over 161 μm

32 Clogging Resistance of Different Filter Media

321 Initial Hydraulic Conductivity of Filter Media )e air-void fractions and initial hydraulic conductivity of the fivetypes of filter media with three grain size levels were testedand the results are illustrated in Figure 7

It can be seen from Figure 7 that the grain size presentedlimited impact on the air-void fractions for each filtermedium though a small increase could be observed with theincrease in grain size )e air-void fractions of Diatomiteand Vesuvianite reached relatively high values of 62 and60 respectively while air-void fractions of ZeoliteCeramsite and Slag remained at the levels of 45ndash50 Asfor the initial hydraulic conductivity just a slight growthcould be observed as the grain size increased Ceramsitepresented much higher hydraulic conductivity of around63mms while hydraulic conductivity was around 45mmsfor Zeolite and Diatomite and around 50mms for Slag andVesuvianite )is indicates that hydraulic conductivity maydepend on not only the air-void fractions but also the mi-crostructure of filter media Ceramsite possesses some parts ofsmooth surface in micro texture (Figure 3(b)) which canaccelerate the flow rate leading to the high hydraulicconductivity

322 Long-Term Clogging Characteristics of Different FilterMedia According to the results in Section 31 the layerthickness and grain size had significant impact on theparticle removal efficiency For comparison study each filtermedium with the same layer thickness of 20 cm and grainsize of 3ndash6mm was selected for this clogging test )eretained ratio of hydraulic conductivity φ and the removalrates of pollutants are plotted against simulation time inFigure 8

It can be seen from Figure 8 that the hydraulic con-ductivity presented roughly a downward trend over simu-lation time For all filter media retained ratio of hydraulicconductivity φ decreased rapidly at the first 3-4 years in-dicating a fast clogging stage )en φ remained stable oreven recovered a little bit for the next 1-2 years indicating a

Table 2 Typical diameter indices of runoff through filter media with different layer thickness

Index(μm)

Influentrunoff

Zeolite Ceramsite Slag Diatomite Vesuvianite10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm

D10 523 211 176 155 881 211 197 317 222 177 263 198 186 220 183 145D50 1936 158 952 951 1069 129 105 445 158 691 196 111 96 164 902 528D90 4007 1028 640 539 3105 957 517 1752 1179 4724 889 673 526 985 478 183

8 Advances in Materials Science and Engineering

Removal rateRetained rate

694

79

891

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(a)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(b)

Removal rateRetained rate

728

858

899

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

627

798

977

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 6 Continued

Advances in Materials Science and Engineering 9

stable clogging stage Afterwards φ showed a slow decliningtrend for the remaining simulation periods indicating agradual clogging stage At the end of the 8-year simulation φwas only 35 26 31 19 and 39 for Zeolite

Ceramsite Slag Diatomite and Vesuvianite respectively)is implies that Vesuvianite possesses superior cloggingresistant property while Diatomite is more prone toclogging

Table 3 Typical diameter indices of runoff through filter media with different layer thickness

Index (μm) Influent runoffZeolite Ceramsite Slag Diatomite Vesuvianite

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8D10 523 163 176 227 188 211 261 153 222 253 190 198 224 169 183 356D50 1936 666 952 125 837 129 220 64 158 164 954 111 140 773 902 455D90 4007 334 640 775 575 957 1360 323 1179 1272 533 673 725 432 478 940

Removal rateRetained rate

573

728

754

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

Removal rateRetained rate

728

845

972

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 6 Effect of grain size on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite) (i)TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

10 Advances in Materials Science and Engineering

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

)e effect of layer thickness of Slag on the particle re-moval efficiency is shown in Figures 5(e) and 5(f) Com-paratively Slag presented particle removal characteristicssimilar to those of Zeolite )e removal rate of TSS for theSlag with each layer thickness was close As for the effluentrunoff through Slag the 161ndash417 μm fraction and 49ndash161 μmfraction of PM decreased significantly as the layer thicknessincreased from 10 cm to 30 cm However Slag showed in-ferior capability to capture the PM with the range over161 μm compared to Zeolite

)e effect of layer thickness of Diatomite on the particleremoval efficiency is presented in Figures 5(g) and 5(h) Itcan be seen that the removal rate of TSS was as insufficient as528 when the layer thickness was 10 cm )e removal rateof TSS increased to 728 and 826 which was comparableto that of Zeolite and Slag when the layer thickness in-creased to 20 cm and 30 cm As for the effluent runoffthrough the Diatomite none of the PMwith the size range of417ndash800 μm and a tiny proportion (22) of PMwith the sizerange of 161ndash417 μm could be observed when the layerthickness was 10 cm despite the low removal rate Un-doubtedly the 49ndash161 μm fraction of PM also decreasedgreatly as the layer thickness increased from 10 cm to 30 cm)is indicates that Diatomite possesses unique capability tocapture the PM with the size range of over 161 μm

)e effect of layer thickness of Vesuvianite on theparticle removal efficiency is illustrated in Figures 5(i) and5(j) It can be seen that the removal rate of TSS increasedgreatly from 645 to 845 as the layer thickness increasedfrom 10 cm to 20 cm However the removal rate remained atthe same level when the layer thickness increased from 20 to30 cm As for the effluent runoff through the Vesuvianite thePSD presented similar trends to that of Diatomite When thelayer thickness was 10 cm none of the PM with fraction of417ndash800 μm and a tiny proportion (24) of PMwith the sizerange of 161ndash417 μm could be observed Moreover all of the49ndash161 μm fractions of PM were captured by Vesuvianitewhen the layer thickness reached 30 cm

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 2 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased sharply )is implies thatall the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices decreased with an increasing layer thickness It isnoticeable that when the layer thickness was 10 cm the d50and d90 of effluent from Ceramsite and Slag were muchbigger than those of the other three filter media but thediameter indices became comparable when the layerthickness increased to 20 cm Effluent from Vesuvianitepresented the smallest diameter indices indicating that itpossesses superior capability to capture particles

Overall different filter media showed great differences inparticle removal characteristics also impacted significantlyby the layer thickness When the layer thickness was 10 cmCeramsite presented a higher removal rate but the fractionover 161 μm of PM could not be captured effectively whileDiatomite and Vesuvianite presented the opposite trends)is indicates that both of the particle capture capability and

the removal rate should be considered for filter media se-lection When the layer thickness reached 20 cm all the fivefilter media showed satisfactory particle removal efficiencyand Vesuvianite presented the highest removal rate and thebest capability to capture coarse particles

312 Effect of Grain Size of Filter Media )ree grain sizelevels of 1ndash3mm 3ndash6mm and 6ndash8mm were prepared foreach filter medium to investigate the effect of grain size onthe particle removal efficiency According to the layerthickness test results 20 cm was selected for each filtermedium in this test Similarly the removal rate of TSS andthe particle size distribution were used to evaluate theparticle removal efficiency )e results of TSS removal rateand PSD from each filter medium are illustrated in Figure 6

)e effect of grain size of Zeolite on the particle removalefficiency is shown in Figures 6(a) and 6(b) It can be seenthat the grain size had a considerable impact on the removalrate )e removal rate of TSS decreased from 891 to 790as the grain size increased from 1ndash3mm to 3ndash6mm and itfurther reduced to 694 as the grain size increased to6ndash8mm Meanwhile PSD variations could also be observedAs for the effluent runoff through Zeolite almost none of thePM with the size range of over 161 μm was observedHowever the 49ndash161 μm fraction of PM presented a re-markable increase as the grain size increased from 1ndash3mmto 3ndash6mm or 6ndash8mm )is means that all grain sizes ofZeolite can capture the particles with the size range of over161 μm effectively but Zeolite with the grain size of 1ndash3mmpossesses superior particle removal capability

)e effect of grain size of Ceramsite on the particleremoval efficiency is illustrated in Figures 6(c) and 6(d) Itcan be seen that the removal rate of TSS remained at thesame level for Ceramsite with the grain size of 1ndash3mm and3ndash6mm However a big drop in the removal rate could beobserved when Ceramsite with the grain size of 6ndash8mm wasused As for the effluent runoff through Ceramsite none ofthe 161ndash800 μm fractions of PM could be observed whenCeramsite with grain size of 1ndash3mmwas used Neverthelessthere was no big difference in the PSD for Ceramsite withgrain size of 3ndash6mm or 6ndash8mm )e 49ndash161 μm fraction ofPM increased greatly and the 161ndash417 μm fraction of PMcould be observed when Ceramsite with the grain size of3ndash6mm and 6ndash8mmwas used)is indicates that Ceramsitewith the grain size of 1ndash3mm has superior capability toremove coarse particles

)e effect of grain size of Slag on the particle removalefficiency is shown in Figures 6(e) and 6(f) It can be seenthat the grain size did impact the removal rate greatly )eremoval rate of TSS reached as high as 977 when the grainsize of 1ndash3mm was used )en it reduced sharply to 798and 627 as the grain size increased to 3ndash6mm and6ndash8mm PSD variations also changed subsequently As forthe effluent runoff through Slag when the grain size of1ndash3mm was used the 1ndash9 μm and 9ndash49 μm fractions of PMaccounted for 895 of the total particles When the grainsize of 3ndash6mm or 6ndash8mm was used a small proportion of161ndash417 μm fraction of PM could be observed while the

Advances in Materials Science and Engineering 7

49ndash161 μm fraction of PM grew to 199 and 220 re-spectively )is implies that Slag grain sizes of 3ndash6mm and6ndash8mm have equivalent capability to capture particles

)e effect of grain size of Diatomite on the particleremoval efficiency is presented in Figures 6(g) and 6(h) Itcan be seen that the removal rate of TSS remained at thesame level of around 728ndash754 for Diatomite with thegrain size of 1ndash3mm and 3ndash6mm However the removalrate reduced to 573 when Diatomite with the grain size of6ndash8mm was used Meanwhile PSD results did not showobvious variations As for the effluent runoff through Di-atomite none of the PM with the size range of over 161 μmcould be seen )e 1ndash9 μm 9ndash49 μm and 49ndash161 μm frac-tions of PM were close for Diatomite with all the three grainsizes )is indicates that Diatomite possesses excellent ca-pability to capture the particles with the size range of over161 μm despite the differences in grain size

)e effect of grain size of Vesuvianite on the particleremoval efficiency is illustrated in Figures 6(i) and 6(j) It canbe seen that the grain size had a remarkable influence on theremoval rate)e removal rate of TSS reduced from 972 to845 as the grain size increased from 1ndash3mm to 3ndash6mmand it further reduced to 728 as the grain size increased to6ndash8mm As for the effluent runoff through Vesuvianitethere was no big difference in the PSD for the filter mediumwith grain size of 1ndash3mm or 3ndash6mm However the49ndash161 μm fraction of PM increased significantly from 8 to463 when the grain size of 6ndash8mm was used )is in-dicates that Vesuvianite with the grain size of 6ndash8mm hasinferior capability to remove the 49ndash161 μm fraction of PM

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 3 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased dramatically )is impliesthat all the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices grew with an increasing grain size It is noticeablethat when the grain size of 6ndash8mm was used the d50 ofeffluent from Vesuvianite was much bigger than those fromother filter media Meanwhile the d90 of effluent fromCeramsite and Slag was much bigger than those of otherfilter media All the three diameter indices would not be-come comparable only when the grain size of 1ndash3mm wasused for each filter medium

Overall the grain size of filter media did impact theparticle removal efficiency significantly Generally the finerthe grain size is the higher the removal efficiency will bealthough Diatomite with each grain size could capture thecoarse particles effectively All the filter media with the grainsize of 1-3mm presented comparably superior capability to

capture particles but only Slag and Vesuvianite showedremoval rate as high as over 90 When the grain size of3ndash6mm was used accepted removal efficiency could beachieved for each filter medium and Vesuvianite alsopresented both the highest removal rate and the best ca-pability to capture coarse particles When the grain size of6ndash8mm was used Ceramsite and Slag showed inferior re-moval efficiency of PM with the size range of over 161 μm

32 Clogging Resistance of Different Filter Media

321 Initial Hydraulic Conductivity of Filter Media )e air-void fractions and initial hydraulic conductivity of the fivetypes of filter media with three grain size levels were testedand the results are illustrated in Figure 7

It can be seen from Figure 7 that the grain size presentedlimited impact on the air-void fractions for each filtermedium though a small increase could be observed with theincrease in grain size )e air-void fractions of Diatomiteand Vesuvianite reached relatively high values of 62 and60 respectively while air-void fractions of ZeoliteCeramsite and Slag remained at the levels of 45ndash50 Asfor the initial hydraulic conductivity just a slight growthcould be observed as the grain size increased Ceramsitepresented much higher hydraulic conductivity of around63mms while hydraulic conductivity was around 45mmsfor Zeolite and Diatomite and around 50mms for Slag andVesuvianite )is indicates that hydraulic conductivity maydepend on not only the air-void fractions but also the mi-crostructure of filter media Ceramsite possesses some parts ofsmooth surface in micro texture (Figure 3(b)) which canaccelerate the flow rate leading to the high hydraulicconductivity

322 Long-Term Clogging Characteristics of Different FilterMedia According to the results in Section 31 the layerthickness and grain size had significant impact on theparticle removal efficiency For comparison study each filtermedium with the same layer thickness of 20 cm and grainsize of 3ndash6mm was selected for this clogging test )eretained ratio of hydraulic conductivity φ and the removalrates of pollutants are plotted against simulation time inFigure 8

It can be seen from Figure 8 that the hydraulic con-ductivity presented roughly a downward trend over simu-lation time For all filter media retained ratio of hydraulicconductivity φ decreased rapidly at the first 3-4 years in-dicating a fast clogging stage )en φ remained stable oreven recovered a little bit for the next 1-2 years indicating a

Table 2 Typical diameter indices of runoff through filter media with different layer thickness

Index(μm)

Influentrunoff

Zeolite Ceramsite Slag Diatomite Vesuvianite10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm

D10 523 211 176 155 881 211 197 317 222 177 263 198 186 220 183 145D50 1936 158 952 951 1069 129 105 445 158 691 196 111 96 164 902 528D90 4007 1028 640 539 3105 957 517 1752 1179 4724 889 673 526 985 478 183

8 Advances in Materials Science and Engineering

Removal rateRetained rate

694

79

891

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(a)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(b)

Removal rateRetained rate

728

858

899

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

627

798

977

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 6 Continued

Advances in Materials Science and Engineering 9

stable clogging stage Afterwards φ showed a slow decliningtrend for the remaining simulation periods indicating agradual clogging stage At the end of the 8-year simulation φwas only 35 26 31 19 and 39 for Zeolite

Ceramsite Slag Diatomite and Vesuvianite respectively)is implies that Vesuvianite possesses superior cloggingresistant property while Diatomite is more prone toclogging

Table 3 Typical diameter indices of runoff through filter media with different layer thickness

Index (μm) Influent runoffZeolite Ceramsite Slag Diatomite Vesuvianite

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8D10 523 163 176 227 188 211 261 153 222 253 190 198 224 169 183 356D50 1936 666 952 125 837 129 220 64 158 164 954 111 140 773 902 455D90 4007 334 640 775 575 957 1360 323 1179 1272 533 673 725 432 478 940

Removal rateRetained rate

573

728

754

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

Removal rateRetained rate

728

845

972

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 6 Effect of grain size on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite) (i)TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

10 Advances in Materials Science and Engineering

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

49ndash161 μm fraction of PM grew to 199 and 220 re-spectively )is implies that Slag grain sizes of 3ndash6mm and6ndash8mm have equivalent capability to capture particles

)e effect of grain size of Diatomite on the particleremoval efficiency is presented in Figures 6(g) and 6(h) Itcan be seen that the removal rate of TSS remained at thesame level of around 728ndash754 for Diatomite with thegrain size of 1ndash3mm and 3ndash6mm However the removalrate reduced to 573 when Diatomite with the grain size of6ndash8mm was used Meanwhile PSD results did not showobvious variations As for the effluent runoff through Di-atomite none of the PM with the size range of over 161 μmcould be seen )e 1ndash9 μm 9ndash49 μm and 49ndash161 μm frac-tions of PM were close for Diatomite with all the three grainsizes )is indicates that Diatomite possesses excellent ca-pability to capture the particles with the size range of over161 μm despite the differences in grain size

)e effect of grain size of Vesuvianite on the particleremoval efficiency is illustrated in Figures 6(i) and 6(j) It canbe seen that the grain size had a remarkable influence on theremoval rate)e removal rate of TSS reduced from 972 to845 as the grain size increased from 1ndash3mm to 3ndash6mmand it further reduced to 728 as the grain size increased to6ndash8mm As for the effluent runoff through Vesuvianitethere was no big difference in the PSD for the filter mediumwith grain size of 1ndash3mm or 3ndash6mm However the49ndash161 μm fraction of PM increased significantly from 8 to463 when the grain size of 6ndash8mm was used )is in-dicates that Vesuvianite with the grain size of 6ndash8mm hasinferior capability to remove the 49ndash161 μm fraction of PM

Besides the typical diameter indices of all the effluentrunoff are summarized in Table 3 It can be seen thatcompared with the particles in the influent runoff all thethree diameter indices decreased dramatically )is impliesthat all the filter media can capture coarse particles to someextent In terms of each filter medium the three diameterindices grew with an increasing grain size It is noticeablethat when the grain size of 6ndash8mm was used the d50 ofeffluent from Vesuvianite was much bigger than those fromother filter media Meanwhile the d90 of effluent fromCeramsite and Slag was much bigger than those of otherfilter media All the three diameter indices would not be-come comparable only when the grain size of 1ndash3mm wasused for each filter medium

Overall the grain size of filter media did impact theparticle removal efficiency significantly Generally the finerthe grain size is the higher the removal efficiency will bealthough Diatomite with each grain size could capture thecoarse particles effectively All the filter media with the grainsize of 1-3mm presented comparably superior capability to

capture particles but only Slag and Vesuvianite showedremoval rate as high as over 90 When the grain size of3ndash6mm was used accepted removal efficiency could beachieved for each filter medium and Vesuvianite alsopresented both the highest removal rate and the best ca-pability to capture coarse particles When the grain size of6ndash8mm was used Ceramsite and Slag showed inferior re-moval efficiency of PM with the size range of over 161 μm

32 Clogging Resistance of Different Filter Media

321 Initial Hydraulic Conductivity of Filter Media )e air-void fractions and initial hydraulic conductivity of the fivetypes of filter media with three grain size levels were testedand the results are illustrated in Figure 7

It can be seen from Figure 7 that the grain size presentedlimited impact on the air-void fractions for each filtermedium though a small increase could be observed with theincrease in grain size )e air-void fractions of Diatomiteand Vesuvianite reached relatively high values of 62 and60 respectively while air-void fractions of ZeoliteCeramsite and Slag remained at the levels of 45ndash50 Asfor the initial hydraulic conductivity just a slight growthcould be observed as the grain size increased Ceramsitepresented much higher hydraulic conductivity of around63mms while hydraulic conductivity was around 45mmsfor Zeolite and Diatomite and around 50mms for Slag andVesuvianite )is indicates that hydraulic conductivity maydepend on not only the air-void fractions but also the mi-crostructure of filter media Ceramsite possesses some parts ofsmooth surface in micro texture (Figure 3(b)) which canaccelerate the flow rate leading to the high hydraulicconductivity

322 Long-Term Clogging Characteristics of Different FilterMedia According to the results in Section 31 the layerthickness and grain size had significant impact on theparticle removal efficiency For comparison study each filtermedium with the same layer thickness of 20 cm and grainsize of 3ndash6mm was selected for this clogging test )eretained ratio of hydraulic conductivity φ and the removalrates of pollutants are plotted against simulation time inFigure 8

It can be seen from Figure 8 that the hydraulic con-ductivity presented roughly a downward trend over simu-lation time For all filter media retained ratio of hydraulicconductivity φ decreased rapidly at the first 3-4 years in-dicating a fast clogging stage )en φ remained stable oreven recovered a little bit for the next 1-2 years indicating a

Table 2 Typical diameter indices of runoff through filter media with different layer thickness

Index(μm)

Influentrunoff

Zeolite Ceramsite Slag Diatomite Vesuvianite10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm 10 cm 20 cm 30 cm

D10 523 211 176 155 881 211 197 317 222 177 263 198 186 220 183 145D50 1936 158 952 951 1069 129 105 445 158 691 196 111 96 164 902 528D90 4007 1028 640 539 3105 957 517 1752 1179 4724 889 673 526 985 478 183

8 Advances in Materials Science and Engineering

Removal rateRetained rate

694

79

891

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(a)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(b)

Removal rateRetained rate

728

858

899

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

627

798

977

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 6 Continued

Advances in Materials Science and Engineering 9

stable clogging stage Afterwards φ showed a slow decliningtrend for the remaining simulation periods indicating agradual clogging stage At the end of the 8-year simulation φwas only 35 26 31 19 and 39 for Zeolite

Ceramsite Slag Diatomite and Vesuvianite respectively)is implies that Vesuvianite possesses superior cloggingresistant property while Diatomite is more prone toclogging

Table 3 Typical diameter indices of runoff through filter media with different layer thickness

Index (μm) Influent runoffZeolite Ceramsite Slag Diatomite Vesuvianite

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8D10 523 163 176 227 188 211 261 153 222 253 190 198 224 169 183 356D50 1936 666 952 125 837 129 220 64 158 164 954 111 140 773 902 455D90 4007 334 640 775 575 957 1360 323 1179 1272 533 673 725 432 478 940

Removal rateRetained rate

573

728

754

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

Removal rateRetained rate

728

845

972

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 6 Effect of grain size on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite) (i)TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

10 Advances in Materials Science and Engineering

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

Removal rateRetained rate

694

79

891

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(a)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(b)

Removal rateRetained rate

728

858

899

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(c)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(d)

Removal rateRetained rate

627

798

977

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(e)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(f )

Figure 6 Continued

Advances in Materials Science and Engineering 9

stable clogging stage Afterwards φ showed a slow decliningtrend for the remaining simulation periods indicating agradual clogging stage At the end of the 8-year simulation φwas only 35 26 31 19 and 39 for Zeolite

Ceramsite Slag Diatomite and Vesuvianite respectively)is implies that Vesuvianite possesses superior cloggingresistant property while Diatomite is more prone toclogging

Table 3 Typical diameter indices of runoff through filter media with different layer thickness

Index (μm) Influent runoffZeolite Ceramsite Slag Diatomite Vesuvianite

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8D10 523 163 176 227 188 211 261 153 222 253 190 198 224 169 183 356D50 1936 666 952 125 837 129 220 64 158 164 954 111 140 773 902 455D90 4007 334 640 775 575 957 1360 323 1179 1272 533 673 725 432 478 940

Removal rateRetained rate

573

728

754

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

Removal rateRetained rate

728

845

972

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 6 Effect of grain size on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite) (i)TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

10 Advances in Materials Science and Engineering

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

stable clogging stage Afterwards φ showed a slow decliningtrend for the remaining simulation periods indicating agradual clogging stage At the end of the 8-year simulation φwas only 35 26 31 19 and 39 for Zeolite

Ceramsite Slag Diatomite and Vesuvianite respectively)is implies that Vesuvianite possesses superior cloggingresistant property while Diatomite is more prone toclogging

Table 3 Typical diameter indices of runoff through filter media with different layer thickness

Index (μm) Influent runoffZeolite Ceramsite Slag Diatomite Vesuvianite

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8D10 523 163 176 227 188 211 261 153 222 253 190 198 224 169 183 356D50 1936 666 952 125 837 129 220 64 158 164 954 111 140 773 902 455D90 4007 334 640 775 575 957 1360 323 1179 1272 533 673 725 432 478 940

Removal rateRetained rate

573

728

754

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(g)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(h)

Removal rateRetained rate

728

845

972

20 40 60 80 1000Removal rate of TSS ()

1ndash3mm

3ndash6mm

6ndash8mm

(i)

0-1μm1ndash9μm9ndash49μm

49ndash161μm161ndash417μm417ndash800μm

Influent 1ndash3mm 3ndash6mm 6ndash8mm

Vol

ume f

ract

ion

()

0

20

40

60

80

100

(j)

Figure 6 Effect of grain size on particle removal efficiency of different filter media (a) TSS removal rate (Zeolite) (b) PSD based onsubdivided intervals (Zeolite) (c) TSS removal rate (Ceramsite) (d) PSD based on subdivided intervals (Ceramsite) (e) TSS removal rate(Slag) (f ) PSD based on subdivided intervals (Slag) (g) TSS removal rate (Diatomite) (h) PSD based on subdivided intervals (Diatomite) (i)TSS removal rate (Vesuvianite) (j) PSD based on subdivided intervals (Vesuvianite)

10 Advances in Materials Science and Engineering

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8 1ndash3 3ndash6 6ndash8VesuvianiteDiatomiteSlagCeramsite

Air voidsHydraulic conductivity

Zeolite

Air

void

s (

)

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

Hyd

raul

ic co

nduc

tivity

(mm

s)

Figure 7 Air-void fractions and initial hydraulic conductivity of different filter media

RRH

C φ

()

47

35

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

Hydraulic conductivity TNTP

ZnPb

(a)

Figure 8 Continued

Advances in Materials Science and Engineering 11

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

43

26RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(b)

36

31RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(c)

29

19

RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(d)

Figure 8 Continued

12 Advances in Materials Science and Engineering

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

In terms of all the detected types of pollutants theremoval rates increased at the fast clogging stage and thenremained at the same levels as the clogging progressdeveloped which was consistence with the results in[8 11] )is shows that the filtration capability of the filtermedia to capture the pollutants enhanced at the fastclogging stage and then the filtration capability remainedthough the clogging phenomena became more and moresevere )e explanation could be that the retained par-ticulate matter by filter media can capture more pollutantsdue to their relative bigger specific surface areas Besidesthe flow rate of the runoff could be slowed down due to thedeterioration in hydraulic conductivity caused by clog-ging which also could contribute to the higher pollutantremoval rates

As for the stable clogging stage the retained ratio ofhydraulic conductivity φ remained stable or even in-creased slightly )is is owing to unstable state of theretained particulate matter within the filter media )oseparts of PM could be washed away through interlockingpore in the filter media indicating that this clogging stagecould be recovered since no permanent clogging has beenformed As a result this can be considered as the optimumtiming to maintain the filter media so as to recover the airvoids and keep a balance between hydraulic conductivityand filtration capability )erefore according to thechanges in hydraulic conductivity over simulation time itwas proposed that the best maintenance timing is when φreduced to 50 of its initial value As shown in Figure 8marked as dot dash lines when the retained ratio ofhydraulic conductivity φ reduced to 50 it took 47 4336 29 and 43 years for Zeolite Ceramsite Slag Diat-omite and Vesuvianite respectively It is worthwhile topoint out that the particle removal rate is not related to theclogging resistance of filter media For instance Diatomitepresented the lowest particle removal rate of 728 which

meant that this medium captured the least amount ofparticulate matter However it was more prone to clog-ging and needed maintenance only after 29 years ofoperation Ceramsite and Vesuvianite possessed higherparticle removal rate of around 85 but maintenancewould not be necessary till 43 years of operation )isphenomenon could be caused by the differences in themicrostructure of filter media

In addition it was found that most of the visible par-ticulate matter was captured within the depth of 3 cmndash7 cm(Figure 9) since the filter media on the top 3 cm were floatedcaused by the ldquowashing effectrdquo of the runoff which wasconsistent with the result from [28]

43

40RRH

C φ

()

0102030405060708090

100

RRH

C φ

()

0102030405060708090

100

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

0102030405060708090100

Rem

oval

rate

of p

ollu

tant

()

1 2 3 4 5 6 7 80Simulation time (year)

1 2 3 4 5 6 7 80Simulation time (year)

Hydraulic conductivityTSSCOD

Hydraulic conductivity TNTP

ZnPb

(e)

Figure 8 Long-term clogging test results of different filter media Variations of hydraulic conductivity and pollutant concentration withsimulation time (a) Zeolite (b) Ceramsite (c) Slag (d) Diatomite and (e) Vesuvianite

3cm

7cm

Figure 9 Deposited position of captured particulate matter

Advances in Materials Science and Engineering 13

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

4 Conclusions

)is study focused on evaluating the capability to captureparticulate matter and clogging characteristics of five typesof filter media Long-term clogging tests were performed foreach filter medium by self-developed equipment )e con-clusions can be derived as follows

(1) Different types of filter media present various ca-pabilities to capture particulate matter resulting inthe differences in the TSS removal rate and PSD ofcaptured PM

(2) )e capability of different filter media to capture PMis also layer thickness and grain size dependentGenerally a thicker layer and finer grain size wouldbe more effective in capturing PM

(3) All the five types of filter media can capture all theparticulate matter with the size range of 161ndash800 μmand most of the particles with the size range of49ndash161 μm when suitable filter media are used in-dicating that the PM with the size of over 49 μm isdominant in clogging

(4) )e clogging process of each filter medium developsrapidly at the first 3-4 years and then presents a slowdecreasing trend To prevent permanent cloggingthe proposed maintenance timing for ZeoliteCeramsite Slag Diatomite and Vesuvianite is after47 43 36 29 and 43 yearsrsquo operationrespectively

(5) Higher TSS removal rate may not result in morerapid clogging phenomenon Vesuvianite possessesboth superior capability to capture particulate matterand clogging resistance)erefore both TSS removalrate and clogging resistance should be taken intoconsideration for filter media selection

Data Availability

)e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)e authors wish to express their appreciation for thesupport received from the National Natural Science Foun-dation of China (51578481) and Jiangsu Overseas VisitingScholar Program for University Prominent Young amp Mid-dle-Aged Teachers and Presidents

References

[1] J Vaze and F H S Chiew ldquoNutrient loads associated withdifferent sediment sizes in urban stormwater and surface

pollutantsrdquo Journal of Environmental Engineering vol 130no 4 pp 391ndash396 2004

[2] E Risch J Gasperi M-C Gromaire et al ldquoImpacts fromurban water systems on receiving waters - how to account forsevere wet-weather events in LCArdquoWater Research vol 128pp 412ndash423 2018

[3] P Zhang Y Cai and J Wang ldquoA simulation-based real-timecontrol system for reducing urban runoff pollution through astormwater storage tankrdquo Journal of Cleaner Productionvol 183 pp 641ndash652 2018

[4] USEPA ldquoEnvironmental indicators of water quality in theUnited Statesrdquo Art Panorama vol 235 no 3 pp 1823ndash18282006

[5] G Straffelini R Ciudin A Ciotti and S Gialanella ldquoPresentknowledge and perspectives on the role of copper in brakematerials and related environmental issues A critical as-sessmentrdquo Environmental Pollution vol 207 pp 211ndash2192015

[6] N C Okochi and D W McMartin ldquoLaboratory investiga-tions of stormwater remediation via slag Effects of metals onphosphorus removalrdquo Journal of Hazardous Materialsvol 187 no 1ndash3 pp 250ndash257 2011

[7] H S Kandra D McCarthy T D Fletcher and A DeleticldquoAssessment of clogging phenomena in granular filter mediaused for stormwater treatmentrdquo Journal of Hydrologyvol 512 pp 518ndash527 2014

[8] B E Hatt N Siriwardene A Deletic and T D FletcherldquoFilter media for stormwater treatment and recycling )einfluence of hydraulic properties of flow on pollutant re-movalrdquo Water Science amp Technology vol 54 no 6-7pp 263ndash271 2006

[9] A Parvan S Jafari M Rahnama S N apourvari andA Raoof ldquoInsight into particle retention and clogging inporous media A pore scale study using lattice Boltzmannmethodrdquo Advances in Water Resources vol 138 Article ID103530 2020

[10] B E Hatt T D Fletcher and A Deletic ldquoTreatment per-formance of gravel filter media Implications for design andapplication of stormwater infiltration systemsrdquo Water Re-search vol 41 no 12 pp 2513ndash2524 2007

[11] H Li A P Davis and F Asce ldquoUrban particle capture inbioretention media I Laboratory and field studiesrdquo Journal ofEnvironmental Engineering vol 134 no 6 pp 409ndash418 2008

[12] N Siriwardene A Deletic and T Fletcher ldquoClogging ofstormwater gravel infiltration systems and filters Insightsfrom a laboratory studyrdquo Water Research vol 41 no 7pp 1433ndash1440 2007

[13] A Kang H Mao B Li C Kou X Xu and B JahangirildquoInvestigation of selective filtration characteristics of filtermedia for pavement runoff treatmentrdquo Journal of CleanerProduction vol 235 pp 590ndash602 2019

[14] X Hu K Dai and P Pan ldquoInvestigation of engineeringproperties and filtration characteristics of porous asphaltconcrete containing activated carbonrdquo Journal of CleanerProduction vol 209 pp 1484ndash1493 2019

[15] N Hu J Zhang S Xia et al ldquoA field performance evaluationof the periodic maintenance for pervious concrete pavementrdquoJournal of Cleaner Production vol 263 no No 121463 pages2020

[16] Y Ma X Chen Y Geng and X Zhang ldquoEffect of clogging onthe permeability of porous asphalt pavementrdquo Advances inMaterials Science and Engineering vol 2020 Article ID4851291 pp 1ndash9 2020

14 Advances in Materials Science and Engineering

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15

[17] S Alber W Ressel P Liu G Lu D Wang and M OeserldquoAnalyzing the effects of clogging of PA internal structurewith artificial soiling experimentsrdquo International Journal ofTransportation Science and Technology vol 8 no 4pp 383ndash393 2019

[18] G Lu ZWang P Liu DWang andM Oeser ldquoInvestigationof the hydraulic properties of pervious pavement mixturescharacterization of Darcy and non-Darcy flow based on poremicrostructuresrdquo Journal of Transportation Engineering PartB Pavements vol 146 no 2 Article ID 04020012 2020

[19] H Wang J Xin X Zheng et al ldquoClogging evolution inporous media under the coexistence of suspended particlesand bacteria Insights into the mechanisms and implicationsfor groundwater rechargerdquo Journal of Hydrology vol 582Article ID 124554 2020

[20] J Fetzer M Holzner M Plotze and G Furrer ldquoClogging ofan Alpine streambed by silt-sized particles - Insights fromlaboratory and field experimentsrdquo Water Research vol 126pp 60ndash69 2017

[21] F J Charters T A Cochrane and A D OrsquoSullivan ldquoParticlesize distribution variance in untreated urban runoff and itsimplication on treatment selectionrdquo Water Research vol 85pp 337ndash345 2015

[22] Z Shen J Liu G Aini and Y Gong ldquoA comparative study ofthe grain-size distribution of surface dust and stormwaterrunoff quality on typical urban roads and roofs in BeijingChinardquo Environmental Science and Pollution Research vol 23no 3 pp 2693ndash2704 2016

[23] R J Winston and W F Hunt ldquoCharacterizing runoff fromroads Particle size distributions nutrients and gross solidsrdquoJournal of Environmental Engineering vol 143 no 1 ArticleID 04016074 2017

[24] Y Li S-L Lau M Kayhanian and M K Stenstrom ldquoParticlesize distribution in highway runoffrdquo Journal of EnvironmentalEngineering vol 131 no 9 pp 1267ndash1276 2005

[25] M Jartun R Tore E Steinnes and T Volden ldquoRunoff ofparticle bound pollutants from urban impervious surfacesstudied by analysis of sediments from stormwater trapsrdquoScience of the Total Environment vol 396 no 2-3 pp 147ndash163 2008

[26] C Wang H Wang M Oeser and M R Mohd HasanldquoInvestigation on the morphological and mineralogicalproperties of coarse aggregates under VSI crushing opera-tionrdquo International Journal of Pavement Engineeringvol 2020 Article ID 1714043 pp 1ndash14 2020

[27] H Wang C Wang Y Bu Z You X Yang and M OeserldquoCorrelate aggregate angularity characteristics to the skidresistance of asphalt pavement based on image analysistechnologyrdquo Construction and Building Materials vol 242Article ID 118150 2020

[28] E Q Segismundo B-S Lee L-H Kim and B-H KooldquoEvaluation of the impact of filter media depth on filtrationperformance and clogging formation of a stormwater sandfilterrdquo Journal of Korean Society on Water Environmentvol 32 no 1 pp 36ndash45 2016

Advances in Materials Science and Engineering 15