Leachate management -Constructed wetlands-

Yuka Ogata

*National Institute for Environmental Studies

Lecture 4

2

Topics

1, Introduction (landfill leachate)

2, Leachate management

3, Leachate treatment

4, Constructed wetland

5, Our current research

6, Conclusion

What is landfill leachate?

Landfill

・ Aqueous effluent generated by rainwater trough waste ・ Eluted various contamination by waste

4

What is landfill leachate?・ Organic matter, ・ Nutrient, ・ Inorganic salts・ Heavy metals (Fe, Mn, Cu, Cr, Pb etc…)・ Toxic chemicals (bisphenol A, 1,4-dioxane, alkylphenols etc…)

Change the leachate characteristics

Parameters Young leachate Stabilized leachate

Age <5 years >10 years

Composition Low molecular weight compounds (ex, VFAs: acetic acid, propionic acid, butyric acid)

High molecular weight compounds(ex, humic acid, fulvic acid)

pH 4.5-6.5 7.5-9.0

NH3-N (mg/L)

500-2000 400-5000

BOD (mg/L) 4000-13000 20-1000

COD (mg/L) 6000-60000 5000-20000

5

Problem of landfill leachate

・ Groundwater pollution

Landfill

Leakage

It is important to properly manage leachate

Concern about environmental pollution

・ Final cover (reduction of infiltration rainwater)

6

・ Collection

・ Treatment

・ Prevention of leakage

Leachate management

・ Leachate collection・ Drainage pipe

・ Impermeable liner

Multiple safety structure

・ Water purification・ Water reduction

・ Reduction of water volume・ Final cover (reduction of infiltration rainwater)

Waste

7

Leachateadjustment tank

Groundwatercollecting pipe

Liner(Impermeable liner)

Flood control reservoir

Leachate treatment plant

Vertical liner

Discharge

Leachate collection and drainage pipe

Biological treatment ・ Activated sludge　・ Upflow anaerobic sludge blankets (UASB)

7

Leachate treatmentNatural system ・ Stabilization pond ・ Constructed wetland (CW) ・ Leachate recirculation ・ Aerated lagoons (need aeration)

Physicochemical treatment ・ Coagulation sedimentation ・ Filtration ・ Fenton’s oxidation ・ Advanced oxidation process (UV, O3, H2O2)

Today’s topic

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What is a CW?

Engineered ecosystems that have been designed to utilize the natural processes (wetland vegetation, medium, microbial associations) to treating wastewater

Constructed wetland (CW)

Plant Water purification ・ Nutrients uptake ・ Activated microorganism 　Water reduction ・ Evapotranspiration

Evapotranspiration

Water purification

Medium(Sand, gravel etc..)

Water purification ・ Filtration ・ Adsorption

Microorganism　

Water purification ・ Degradation

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Application

Type of wastewater

Sewage

Domestic sewage

Animal wastes

Metal ores mine drainage

Shrimp aquaculture

Paper and pulp

Landfill leachate

Woodwaste leachate

Mainly, CW have been applied to treat municipal wastewater and domestic sewage in Europe, United states.

The first experiments had been conducted by Kathe Seidel in Germany in the early 1950s

Various type of wastewater

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・ Low cost

・ Little maintenance

・ Easy operation ・ Low energy

・ Ecological system

Advantage

Disadvantage

・ Large area

・ Plant die down in winter

・ Time-consumption

・ Difficult stable treatment

Limited application Easier application?

Over come

・ Tropical zone (ex,Thailand)

Advantage and Disadvantage

・ Temperate zone (ex,Japan)

Landfill

Leachate

Discharge

Recirculation

CWPond

Pond

Sustainable leachate management9

Proposal

Water regulation

Evapotranspiration

Water purification

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Purpose of our research

Evaluation of the feasibility and performance of applying CW to treat landfill leachate in Southeast Asia

Construction and operation of affordable pilot-scale CW in landfill site in Southeast Asia

Evaluation of the applicability of plant for landfill leachate treatment

Evaluation of the effect of water reduction and purification by CW.

Natural pond

Leachatepond 1

Site descriptionSai Noi landfill site

Waste ： 843 t/day

60 km

SiteLocated about 60 km north-western of Bangkok city, Nonthaburi province, Thailand

Sampling: 4/25, 6/20, 8/8, 11/27

Mean Min-Max

Air temp. 36.8 32.7-43.0

Water temp. 33.4 32.6-34.7

pH 9.4 9.3-9.5

EC (mS/cm) 15.1 10.1-17.6

TS (mg/L) 14964 13545-16082

CODcr (mg/L) 1685 963-1980

TOC (mg/L) 564 339-674

TP (mg/L) 7.8 6.0-11.1

TN (mg/L) 70.4 54.3-80.5

NH4+ (mg/L) 4.4 3.3-6.3

Cl- (mg/L) 4599 2840-5474

Landfill leachate characteristics

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ConstructionPilot-scale of CW (1.0 m [width] × 2.0 m [length] × 1.0 m [depth])

Operation

Measurement・ Plant number・ Water quantity (influent, effluent)・ Water quality

Influent volume Duration Time of Influent

Time of effluent

Groundwater 75 L/day(37.5 L/m2day)

About 2 months (8/8-10/13)

9:00 15:30

25% Leachate 75 L/day(37.5 L/m2day)

About 2 weeks(10/14-10/25)

9:000 8:30(next day)

50% Leachate 75 L/day(37.5 L/m2day)

About 2 weeks(10/26-11/11)

9:000 8:30(next day)

100% Leachate 75 L/day(37.5 L/m2day)

About 1 week(11/12-11/18)

9:000 8:30(next day)

Plant growth

2013 8 Aug. 2013 21 Oct. 2013 25 Nov.19 shoots/m2, 120 cm 111 shoots/m2, 200 cm61 shoots/m2

Groundwater 75 L/day Diluted leachate 75 L/day

× 1.7

0

50

100

150

8/8 10/21 11/25

×3.3

×6.0

Pla

nt d

ensi

ty(s

hoot

s/m

2 )

Pla

nt h

eigh

t (s

hoot

s/m

2 )

Good growth of cattail in CW

0

20

40

60

80 2

1-O

ct.

22-O

ct.

24-O

ct.

25-O

ct.

26-O

ct.

28-O

ct.

1-N

ov

.2

-No

v.

4-N

ov

.5

-No

v.

6-N

ov

.7

-No

v.

11-N

ov.

12-N

ov.

14-N

ov.

18-N

ov.

19-N

ov.

20-N

ov.

21-N

ov.

22-N

ov.

Water reduction(Evapotranspiration)

Influ

ent

and

efflu

ent

(L/d

ay)

Influent

Effluent

Effect of water reduction 40 L/day (53 % of influent)

Date

40 L

0

20

40

60

80

100

050000

100000150000200000250000300000350000

In Eff In Eff In Eff

25% 50% 100%

Water purification

0

20

40

60

80

100

0

10000

20000

30000

40000

In Eff In Eff In Eff

25% 50% 100%

0

20

40

60

80

100

0

500

1000

1500

2000

In Eff In Eff In Eff

25% 50% 100%

Load

(m

g/m

2 )

Rem

oval

rat

io (

%)

TS(Total Solids)

TC(Total carbon)

TKN(Total Kjeldahl Nitrogen)

Removal efficiency of TS, TC and TKN by CW were 55-69, 51-57, 57-61%

DS: Dissolved SolidsSS: Suspended solidRemoval ratio (%)

TOC: Total organic carbonIC: Inorganic carbonRemoval ratio (%)

Org-N: Organic nitrogenNH4-N :Ammonia nitrogenRemoval ratio (%)

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Conclusion

Prevention of leakage, Collection, Reduction of water volumeTreatment

Multiple safety structure

Leachate management

Constructed wetland・ Artificial system of water treatment using wetland with vegetation designed to remove contaminants

・ Although CW needs area for treatment, it can be operated as low-cost, easy operation and maintenance

Our research

・ Evaluation of the feasibility and performance of applying CW to treat landfill leachate in Southeast Asia (Sai Noi landfill site, Thailand)

・ Cattails could be utilized for CW treating high salinity landfill leachate・ Water reduction: 40 L (53%), Removal efficiency (TS, TC, TKN) 51-69%