Expanded clay and lava rock as potential filter media for nutrient

Rob Van Deun - Mia Van Dyck KHKempen, Geel, Belgium

Expanded clay and lava rock as potential filter media for nutrient

removal in vertical subsurface flowconstructed wetlands

Rob Van Deun, Mia Van DyckKatholieke Hogeschool Kempen, Geel, Belgium

SWS European Chapter Meeting29th June – 3rd July 2008

Kuressaare, Saaremaa, Estonia


Introduction

Lightweight Expanded Clay Aggregates:Literature possible P-removalArgex ??? (“Flemish” LECA)

Argex 0/4• Aggregate size: 0 – 4 mm


Introduction

Lava rock:Commercial products: CW’s treatment of wastewater, water from fish ponds, swimming ponds

• Two types: size: 2 – 12 mm and 8 – 16 mm


IntroductionOptimizing nutrient removal with constructed

wetlands

Methods and MaterialsColumn studies: Infiltration columns

Height 80cm

Hydraulic loading50 l / m².d

45 ppm N (NH4NO3) + 15 ppm P (KH2PO4)

Sampling


Methods and MaterialsAdsorption testsDetermining maximum adsorption capacityMethod (described by Seo, 2005):• 10 g of filter media• Blanks + different P- or N-solutions (100ml)• Continuously shaken for 24 h • After settling, supernatant was filtered

Langmuir equation apparent adsorption capacity


PhosphorusExperiment 1: 15 mgP/l - 50 l/m².d

Results after 6 months:

Removal: 89.7% 37.7% 45.1%

Experiment 1: Phosphorus

0

0,5

1

1,5

2

2,5

3

argex 0-4 lava 8/16 lava 2/12

g P in

out


PhosphorusLineair Langmuir plot: Argex 0-4

Langmuir equation:Ce/q = Ce/b + 1/a.bCe/q = 1.2791.Ce + 28.333

b = apparent maximum adsorption capacity

b = 0.78 mgP/g

y = 1,2791x + 28,333R2 = 0,9499

0

50

100

150

200

250

300

350

400

0 50 100 150 200 250 300

Ce

Ce/

q

PhosphorusInfiltration columns:

Height 80cm

Hydraulic loading50 l / m².d

Argex (LWA)15 ppm P (KH2PO4)

75 ppm P (KH2PO4)

150 ppm P (KH2PO4)

Sampling


PhosphorusExperiment 2: column study: maximum adsorption

capacity Argex 0-475 mg P/l

0,0

100,0

200,0

300,0

400,0

500,0

600,0

700,0

0,0 100,0 200,0 300,0 400,0 500,0 600,0 700,0

total P added mg P / kg

tota

l P a

dsor

bed

mg

P / k

g

150 mg P/l

0,0

200,0

400,0

600,0

800,0

1000,0

1200,0

1400,0

0,0 200,0 400,0 600,0 800,0 1000,0 1200,0 1400,0

total P added mg P / kg

tota

l P a

dsor

bed

mg

P / k

gmaximum adsorption capacity = 0.67 mgP/g

Langmuir = 0.78 mgP/g


Phosphorus

Z. Tong, et al. (1996)

Tota

l Met

al m

g/g

Ca

mg/

g

P-s

orpt

ion

mg

P/g

Filtralite 589 310LECA 226 85Argex 0-4 213 14

2.210.5650.781

Arkansas LW 140 12 0.037


PhosphorusLineair Langmuir plot:

Argex with Fe2O3 and without Fe2O3

b = 0.84 mgP/g b = 0.43 mgP/g

R2 = 0,9624

R2 = 0,9943

0100200300400500600700800900

1000

0,00 50,00 100,00 150,00 200,00 250,00 300,00 350,00 400,00

Ce

Ce/

q

with Fe2O3

without Fe2O3


Phosphorus

Adsorption tests max. adsorption capacity = 0.4 mgP/g

Lineair Freundlich plot: Lava 2/12

log q = log kf + log Ce1n

R2 = 0,9609

-1,6

-1,4

-1,2

-1

-0,8

-0,6

-0,4

-0,2

00 0,5 1 1,5 2 2,5 3

log Ce (mg P/l)

log

q (

mg

P/g)


PhosphorusFreundlich isotherm:

0.914.810.22Argex 0-40.961.620.008Lava 2/12

R2nkf

log q = log kf + log Ce1n

Langmuir isotherm: Ce/q = Ce/b + 1/a.b

0.950.782Argex 0-40.720.410Lava 2/12

R2b


NitrogenExperiment 1: 45 mgN/l - 50 l/m².d

Results after 6 months:

0

100

200

300

400

500

600

700in ou

t in out in out

mgN

/kg

Ammonium mgN/kg Nitrate mgN/kg

Argex 0-4 Lava 2/12 Lava 8/16


NitrogenExperiment 1 16 weeks from the start

Nitrate concentration mgN/l

0

20

40

60

0 20 40 60 80 100 120

days

mgN

/l

Influent effluent Argex 0-4 effluent Lava 2/12

0

20

40

60

80

100

120

140

in outAmmoni um mgN/ k g Ni t r a t e mgN/ k g

Argex 0-4


NitrogenDuring nitrification:

Nitrogen mass balance mgN/kg Lava 8/16Influent

49%51%

Ammonium Nitrate

Nitrogen mass balance mgN/kg Lava 8/16Effluent

15%

52%

33%

Ammonium Nitrate nitrate nitrification

Nitrogen mass balance mgN/kg Lava 2/12Influent

48%52%

Ammonium Nitrate

Nitrogen mass balance mgN/kg Lava 2/12Effluent

10%

54%

36%


Nitrogen mass balance mgN/kg Argex 0-4Influent

49%51%

Ammonium Nitrate

Nitrogen mass balance mgN/kg Argex 0-4Effluent

31%

53%

16%



NitrogenExperiment :

Nitrate in effluent (cumulated)

0100200300400500600

0 5 10 15 20 25 30 35 40 45 50

days

mg

N

Influent Lava 2/12 Lava 2/12 boiled Lava 2/12 ATU

Lava 2/12: + 45 ppm N (NH4NO3) Lava 2/12 washed with boiling water: + 45 ppm N (NH4NO3) Lava 2/12: + 45 ppm N (NH4NO3) + AllylThioUrea (nitrificationinhibitor)


Nitrogen

Experiment 3: Total Nitrogen removal

36.5Lava + ATU12.7Lava (boiled)4.6Lava

% removal


Nitrogen

Adsorption tests

Argex 0-4: Ammonium: no adsorptionLava 2/12: Ammonium: adsorption capacity 0.15 mgN/g

Argex 0-4: Nitrate: adsorption capacity 0.10 mgN/g


Conclusions• Argex P-adsorption

• In a constructed wetland?

• Quality ?

• Lava rock: Nitrification in a multi-stage system


Thank you!!!

AKNOWLEDGMENTS• Supported by the Flemish Ministry for Economy, Enterprise, Science, Innovation and Foreign Trade;• Argex nv, Kruibeke, Belgium;• Dockx en Co nv, Mechelen, Belgium• KVLT, Geel, Belgium

Documents

Expanded clay and lava rock as potential filter media for nutrient