Session 4_Soil Aquifer Treatment for WWT and Reuse_2011

Soil Aquifer Treatment (SAT)

S.Sharma/IHE_2011 1

Soil Aquifer Treatment (SAT) for Wastewater Treatment and ReuseWastewater Treatment and Reuse

Saroj SharmaEmail: [email protected]

December 2011Delft, The Netherlands

Contents

• Introduction• Factors affecting performance of SAT• Removal of different contaminants during SAT

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S.Sharma/IHE_2011 2

Natural Systems for Treatment Water Treatment Wastewater Treatment

and ReuseTerrestrial System(Soil/Aquifer-based)

1. Bank Filtration2 Artificial Recharge

1. Slow Rate Irrigation2 Overland Flow(Soil/Aquifer-based)

Managed Aquifer Recharge (MAR)

2. Artificial Recharge3. Sub-surface GW Treatment

2. Overland Flow3. Soil Aquifer Treatment

Aquatic System

Vegetation-based(macrophytes)

1. Constructed Wetlands2. Water Hyacinths

Pond-based(Storage Reservoirs)

1. Anaerobic2 Facultative (Algal ponds)(Storage Reservoirs) 2. Facultative (Algal ponds)3. Aerobic4. Maturation

- Hybrids : Different combinations of natural systems and conventional systems- Commercial systems: “Living Machines”, “Eco Restorers”

- From decentralised (household level) to centralised (city level) systems


• Infiltration of wastewater effluent through the vadose (unsaturated) zone to recharge the underlying aquifer(unsaturated) zone to recharge the underlying aquifer

• Vadose and saturated zone treatment

• Long-term storage of renovated water: aquifer storage and recovery

4

• Natural and sustainable treatment- Removal of organics (DOC & trace organics) - Removal of microorganisms (bacteria, viruses, protozoa) - Removal of nitrogen (Ammonia + Nitrate)


S.Sharma/IHE_2011 3

SAT: Infiltration to Recovery (Mekorot, 2004)

Why SAT is important ?• Alleviate water shortages; wastewater effluent as a

(potable) water resource

• Augment existing sources; replenish diminishing GW

• Eliminate additional treatment;an alternative to advanced/tertiary treatment:- Reclaimed/recycled (waste)water - Storm water

S f t

6

- Surface water

• Salt water intrusion barrier

• Potential worldwide application, depending on geology, soils, hydrology, etc.


S.Sharma/IHE_2011 4


Reclaimed Wastewater

7

PROCESS/PROCESS/PARAMETERPARAMETER

INFILTRATIONINFILTRATIONINTERFACEINTERFACE

SOILSOIL--PERCOLATIONPERCOLATION

GROUNDWATERGROUNDWATERTRANSPORTTRANSPORT

Treatment Filtration Biodegradation Biodegradation

Comparison of Typical SAT Zones

Treatment Mechanisms

Filtration , Biodegradation

Biodegradation , Adsorption

Biodegradation, Adsorption, Dilution

Transport Saturated Unsaturated Saturated

Residence Time Minutes Hours to Days Months to Years

Travel Distance Centimeters 3 – 30 m Variable

Mixing No No Yes (regional G.W.)

Oxygen (O ) Recharge Water Unsaturated Zone Regional G W

8

Oxygen (O2) Supply

Recharge Water Unsaturated Zone Regional G.W.

Biodegradable Org. Carbon Availability

Excess Excess/Limiting Limiting

Redox Conditions Aerobic Aerobic to Anoxic Anoxic to Aerobic?


S.Sharma/IHE_2011 5

Three Engineered Methods of Groundwater Recharge

9SAT Source: USEPA (2004)

Factors affecting performance of SAT system • Site Specific Conditions

• Source water quality• Geology and Soils• Geology and Soils• Geohydrology

Alluvial, Unconfined AquiferIf confined, injection well

Unsaturated Zone Depth (depth to water table)Aquifer Depth (depth from water table to bedrock)Permeability (Conductivity)

10

• Travel DistanceWell Placement, spacing between the wells

• Travel TimeWell Placement and Operation (Pumping Rate)Permeability (Conductivity)


S.Sharma/IHE_2011 6

Soil Aquifer Treatment for Water ReclamationProcess conditions

- redox, soil type- aquifer type

-HLR time distance

Wastewater treatment plant effluent

Post-treatment

Pre-treatment

Soil Aquifer Treatment

1. Primary2 Secondary

1. None2 Membrane Filtration

1. UF (viruses)2 NF (trace organics)

-HLR, time, distance

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2. Secondary3. Tertiary

2. Membrane Filtration3. O3 , Advanced oxidation4. Combinations

of 2 and 3

2. NF (trace organics)3. Post disinfection

(chlorination)

(Depends on intended use of reclaimed water)

Applicability of SAT

Eliminate additional treatment; an alternative to advanced/tertiary wastewater treatment:

Reclaimed/recycled (waste)water Indirect potable and non-potable reuse

Storm water Surface water

Potential worldwide application, depending on geology, soils, hydrology, etc.

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g gy, , y gy,(presently in USA, Israel, Australia, Europe)


S.Sharma/IHE_2011 7

SAT in Indirect Potable Reuse

Water Reclamation

Wastewater

Surface spreadingor deep injection

Reservoir

13

Water TreatmentConsumer

SAT

Preferences for Natural Systems Barrier (Environmental Returns)

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S.Sharma/IHE_2011 8

General schemes of wastewater generation, treatment, reuse and infiltration to aquifers

(A) commonly-occurring unplanned and uncontrolled situation

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General schemes of wastewater generation, treatment, reuse and infiltration to aquifers

(B) economical interventions aimed at reducing groundwater source pollution risk

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S.Sharma/IHE_2011 9

• Groundwater recharge of effluent achieves additional water quality benefits because of SAT.

S l d l t t b hi d ith t

Advantages of Indirect Potable Reuse based on aquifer recharge

• Seasonal and longer term storage can be achieved without evaporative losses.

• Groundwater recharge protects water against recontamination by birds and mammals and possibly even by human

• Groundwater recharge keeps sunlight away from water, thereby preventing growth of algae and associated water quality problems; to avoid algal growth in a surface reservoir the

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problems; to avoid algal growth in a surface reservoir, the wastewater must be treated to remove nitrogen or phosphorus.

• Reclaimed water recovered from wells is conceived as groundwater, an aesthetically superior and more publicly acceptable source.

SAT Treatment ObjectivesBulk Organic Matter

Natural Organic Matter (NOM)Effl t O i M tt (EfOM)Effluent Organic Matter (EfOM)

Nitrogen SpeciesAmmonia (NH3)Nitrate (NO3

-)Microbes

Viruses an Controlling (most mobile) Organism

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Viruses an Controlling (most mobile) OrganismEffluent-Derived Organic Micropollutants

Pharmaceutically Active Compounds (PhACs)Endocrine Disrupting Compounds (EDCs)


S.Sharma/IHE_2011 10

Water Quality at Phoenix (Arizona), SAT System

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• Suspended solids and particulate organic matter are removed by filtration at or near the soil surface (in first few meters) during SAT.

Removal of Suspended Solids and Bulk Organic Matter

• DOC may be adsorbed by the soil or may be removed from the percolating wastewater by soil biota.

• Suspended solids and bulk organic matter removals are generally not affected by the level of preapplication t t t

20

treatment.

• High hydraulic loadings of wastewaters with highconcentrations of DOC and suspended solids can cause clogging of the soil.



DOC and UVA profile along the depth of the soil column at different hydraulic loading rates with settled primary effluent,

under aerobic conditions

00.25 0.50 0.75 1.00

UVA at 254 nm (absorbance/cm)

010 15 20 25 30 35 40

DOC (mg/L)

1

2

3

4Soil

colu

mn

dept

h (m

)1

2

3

4Soil

colu

mn

dept

h (m

)

21

5

HLR = 1.25 m/day HLR = 2.5 m/day

5


From 35 mg/L,DOC reduced to 15.2 mg/L at HLR = 1.25 m/day, and to 18.4 mg/L at HLR = 2.5 m/day (removal 57% to 49%)

00 5 10 15 20

DOC (mg/L)

00.25 0.50 0.75 1.00

UVA at 254 nm (absorbance/cm)

DOC and UVA profile along the depth of the soil column at different hydraulic loading rates with secondary effluent,

under aerobic conditions

1

2

3

4oil c

olum

n de

pth

(m) 1

2

3

4

oil c

olum

n de

pth

(m)

22

4

5

S


4

5

S


DOC removal 30% at HLR = 1.25 m/day and 15% and HLR = 2.5 m/day



Summary of DOC removal data for SAT with different influents

Type of SAT i fl t

Influent ( /L)

Effluent ( /L)

Removal ffi iinfluent (mg/L) (mg/L) efficiency

(%)

Primary effluent 9-35 7-21 12-62

Secondary effluent

2-24 1.5-16 10-94

23

Tertiary effluent 5-20 2-14 19-80

Source: Sharma et al. (2008)

DOC removal efficiency for different travel distancesduring SAT of secondary effluent

80

90

100

Field studySoil column

30

40

50

60

70

Rem

oval

eff

icie

ncy

(%)

24

0 5 10 15 20 25 30 35 40Travel distance (m)

0

10

20

R



DOC removal efficiency for different travel timesduring SAT of secondary effluent

90

100

Batch reactorsField study

40

50

60

70

80

mov

al e

ffic

ienc

y (%

)

ySoil column

250 10 20 30 40 50 60 70 80

Residence time (days)

0

10

20

30

Rem

BOD Removal for Soil Aquifer Treatment Systems

26

Source: Crites and Tchobanoglous (1998)



Travel Redox Removal Standard

DOC removal from SAT systems treating secondary effluents under different redox conditions

distance (m)

conditions efficiency (%) deviation (%)Range Average

Vadose zone

1-2 Oxic 46-68 59 102-10 Oxic/anoxic* 56-70 63 6

10-20 Oxic/anoxic* 72-73 73 120 40 O i / i * 77 88 77 12

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20-40 Oxic/anoxic* 77-88 77 12Saturated

zone>40 Oxic/anoxic* 77-94 83 8

* Dependent on availability of adequate electron acceptor (NO3-)

Soil type Influent quality (mg/L)

Travel distance

(m)

Travel time

(days)

SAT Removal efficiency

(%)Sandy loam 14 0.82 7 soil column 59-73

Influence of soil type and travel distance/time on DOC removal from secondary effluent during SAT

Sandy loam 14 0.82 7 soil column 59 7311 1 1 soil column 5415 2.5 3 soil column 53

Poorly graded sand

4-12 1 1-2 soil column 26-48

Silty sand 12 1 3 soil column 44Silica sand 4-8 0.3 1 soil column 33-46

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Silica sand 4 8 0.3 1 soil column 33 468 1.0 1 soil column 29

11-14 5 2-4 soil column 15-30Poorly graded silty sand

13 1.0-2.0 2-4 Field SAT 56



• Both nitrification and denitrification are accomplished by soil bacteria. Temperature, pH, soil type and redox conditions affect N removal.

Nitrogen removal during SAT

• The optimum temperature for nitrogen removal is 30°C to 35°C. Both processes proceed slowly between 2°C and 5°C and stop near 0°C.

• Nitrification rates decline sharply in acidic soil diti d h li iti l t i t l

29

conditions and reach a limiting value at approximately pH 4.5. The denitrification reaction rate is reduced substantially by pH values below 5.5.

• Alternating aerobic and anaerobic conditions must be provided for significant nitrogen removal.

• Nitrogen removal is also a function of detention time,C : N ratio (adequate organic carbon source), andanoxic conditions.

Nitrogen removal during SAT

• Nitrogen removal by denitrification requires both adequate organic carbon, which acts as a “food” source for microorganisms, and adequate detention time.

I t f BOD N ti ti f 3 1 i

30

• In terms of BOD:N ratio, a ratio of 3:1 or more is recommended to ensure adequate carbon to drive the denitrification reaction.

• Alternating aerobic and anaerobic conditions must be provided for significant nitrogen removal.



NO3--N profile along the soil column at different HLR when operated with settled primary

effluent under aerobic conditions

2 6 10 14 18

NO3--N (mg/L)

0.0

1.0

2.0

3.0

of s

oil c

olum

n (m

)

Nitrification and denitrification

can be achieved during SAT

31

4.0

5.0

Dep

th o


NO3--N profiles along the soil column at different HLR

when operated with settled primary effluent under aerobic conditions

0.02 6 10 14 18

NO3--N (mg/L)

0 5 2 5 4 5 6 5 8 5

O2 (mg/L)

1.0

2.0

3.0

4.0

Dep

th o

f soi

l col

umn

(m) 0.0

1.0

2.0

3.0

4.0

0.5 2.5 4.5 6.5 8.5

Col

umn

dept

h (m

)

t = 2 dayst = 4 dayst = 18 dayst = 30 days

5.0

HLR = 1.25 m/day HLR = 2.5 m/day5.0

32



Fate of Nitrogen During Wet and Dry Cycle

33

Summary of nitrogen removal at selected SAT sites

34



Nitrogen Removal for Soil Aquifer Treatment Systems

35

Source: (USEPA, 2006)

• Phosphorus removal in SAT is accomplished byadsorption and chemical precipitation.

Phosphorus removal during SAT

• The adsorption occurs quickly and the slower occurring chemical precipitation replenishes the adsorption capacity of the soil.

• Phosphorus removal is highly dependent on soil type and travel time available before abstraction of

l i d t

36

reclaimed water.



Phosphorus Removal for Soil Aquifer Treatment Systems

37

Source: (USEPA, 2006)

• Removal of organic micrpollutants (OMPs) is one of the main concerns in groundwater recharge with treated wastewater and use of reclaimed water.

Removal of Organic Micropollutants

• It is reported that majority of OMPs (including PhACs, EDCs and pesticides) are removed in SAT system if proper travel time and redox conditions are present.

• OMPs can be removed in SAT by sorption and degradation (chemical or biological); OMPs removal i SAT i i il th lt f bi l i l ti it

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in SAT is primarily the result of biological activity.

• Removal rates depend on the constituent, the appliedconcentration, the loading rate, and the presence ofeasily degradable organics to serve as a primarysubstrate, redox conditions and temperature.



Removal efficiency of selected PhACs from secondary effluents in soil columns (HLR = 1.25 m/day, Depth of column = 2.5 m)

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Better removal of ROX, CLA, ERY, TMP (>30%); higher removal under oxic conditions Btri, SMX, SMZ more persistent (< 10%) removalSMX and SMZ are removed better under anoxic than under oxic conditions

TMPSMXSMZERY-H2OROX

25°C 15°C 5°C

CLA

Effect of temperature on removal of PhACs during soil passage

60

80

1002

mov

al [%

]

0

20

40

TMPERY-H2O SMZ SMXCLA

rem

ROX 40



8794

90100

Removal of OMPS in Secondary Effluent during Soil Passage (depth of Soil column = 5 m, HLR = 1.25 m/day)

22

0

71

58

48

36

8075 74

87

0

74 73

0102030405060708090

Aver

age

rem

oval

(%)

41

0

ND

MA

1,4-

Dio

xane

Bez

afib

rate

Caf

fein

e

Car

bam

azep

ine

Clo

fibric

aci

d

Dic

lofe

nac

Feno

prof

en

Gem

fibro

zil

Ibup

rofe

n

Ket

opro

fen

Nap

roxe

n

Acet

amin

ophe

n

Pent

oxify

lline

Phen

acet

ine

A

Source: Caballero (2010)

100

SE+SAT SE+NF SE+SAT+NF

Removal of OMPs in Secondary Effluent in Different Treatment System (depth of Soil column = 5 m, HLR = 1.25 m/day, Membrane used = NF-90)

0

20

40

60

80

100

l c e n n n d e e n e n eage

rem

oval

(%)

42

Gem

fibro

zil

Dic

lofe

nac

Bez

afib

rate

Ibup

rofe

n

Feno

prof

en

Nap

roxe

n

Clo

fibric

aci

d

Caf

fein

e

Car

bam

azep

ine

Acet

amin

ophe

n

Pent

oxify

lline

Ket

opro

fen

Phen

acet

ine

Aver

a

Source: Caballero (2010)



Microbes removal during SAT of secondary effluents

6.00

7.00

Coliform bacteriaColiphageMS2 Virus

3.00

4.00

5.00

Log

rem

oval

Polio virus type 1PRDI virusSalmonella spp

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0.00 1.00 2.00 3.00 4.00 5.00 6.00

Travel distance (m)

0.00

1.00

2.00

44



• Crites, R.W. , Middlebrooks, E. J. and Reed, S.C.(2006) Natural Wastewater Treatment Systems. CRC Publications.

• NCSWS (2001) An Investigation of Soil Aquifer Treatment for Sustainable Water Reuse. Research Project Summary, National Centre

Bibliography

for Sustainable Water Supply, USA.

• NAP (1994) Groundwater Recharge Water of Impaired Quality. National Academy Press. Washington, D.C., USA.

• NAP (2007) Prospects of Managed Underground Storage of Recoverable Water. National Academy Press. Washington, D.C., USA.

• Sharma, S.K., Harun, C.M. and Amy, G. (2008) Framework for assessment of performance of soil aquifer treatment systems Water

45

assessment of performance of soil aquifer treatment systems. Water Science and Technology, 57 (6), 941-946.

• USEPA (2006) Process Design Manual: Land Treatment of Wastewater Effluents. EPA/625/R-06/16. US Environmental Protection Agency, Washington, DC.

• USEPA (2004) Guidelines for Water Reuse. EPA/625/R-04/108. US Environmental Protection Agency, Washington, DC.

Documents

Session 4_Soil Aquifer Treatment for WWT and Reuse_2011