Application on Semi-aerobic Landfill Technology in in Tropical Climate: Lysimeter experiment of Thailand

Chart Chiemchaisri, Noppharit Sutthasil, Komsilp Wangyao, Kazuto Endo, Masato Yamada

Department of Environmental Engineering, Faculty of Engineering, Kasetsart University, Joint Graduate School of Energy and Environment, King Mongkut’s University of Technology Thonburi, Research Center for Material Cycles and Waste Management, National Institute for Environmental Studies, Japan

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Anaerobic vs Aerobic landfills

Anaerobic (Conventional) Landfill The stabilization of most organic waste in landfill took place under

absence of oxygen. High organic strength leachate was generated during acid phase

followed by long term stabilization in methane phase. High CH4 and CO2 in gas produced during methane phase

Semi-aerobic (Fukuoka Method) and Aerobic (forced aeration) Landfill

Introduction of air yielding aerobic degradation in some or whole part of waste body.

Acceleration of waste stabilization and improvement of leachate qualities

Reducing CH4 emission

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Objective of this research

To investigate the applicability of semi-aerobic landfill technology in tropical climate

How effective can the air diffuse into the waste body under high moisture condition?

To study the effect of initial waste placement (degree of compaction) and leachate retention on waste stabilization, leachate qualities and gas production in semi-aerobic and anaerobic lysimeters.

To determine methane emission ratio between semi-aerobic and anaerobic conditions

Methane Correction Factor (MCF) for semi-aerobic landfill.

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Methane Correction Factor (MCF) in IPCC Guidelines

MCF indicates degree of anaerobic condition which creates and emits methane gas from solid waste disposal site.

MCF depends on design and operating condition of the landfills. It can also change with time.

IPCC proposed the following default MCF for different types of landfills

Type of Site Methane Correction Factor (MCF) Default Values

Managed – Anaerobic 1.0

Managed - Semi-Aerobic 0.5

Unmanaged – Deep (>5 m deep) and/or high water Table

0.4

Unmanaged – Shallow (<5 m deep) 0.8

Uncategorised SWDS 0.6

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Lysimeters

Sm = Semi-aerobic Landfill condition An = Anaerobic Landfill condition

Sm I Sm II An I An II

Pan collector of rainwater (70% of lysimeter area)

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Lysimeters Condition Sm I Sm II An I An II

Operating Condition Semi-aerobic Semi-aerobic Anaerobic Anaerobic

Waste compaction No compaction

Typical compaction

Typical compaction

Typical compaction

Waste density (kg/m3) 600 750 700 700

Leachate drainage Completed drainage

Completed drainage

0.6 m leachate

head (normal operation)

Fully submerged condition

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Waste Composition & Characteristics

Food 20%

Paper 19%

Foam 3% Wood

6%

Plastic 16%

Vinyl 17%

Glass 19%

Wet Composition

Food 14% Paper

16%

Foam 3%

Wood 7%

Plastic 18%

Vinyl 15%

Glass 27%

Dry Composition

The waste composition represents average MSW

characteristics of Thailand

• Volatile Solids 79.19 % • Carbon ( C) 43.99 % • Oxygen (O) 4.81 % • Hydrogen (H) 48.41 % • Nitrogen (N) 2.24 % • Phosphorus (P) 0.16 % • Sulfur (S) 0.39 %

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In-situ monitoring parameters Temperature Probes

Gas Extraction Tube

Moisture Sensors

Data Logging System

Tedlar Bag for GC-analysis

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Sensors installation on the lysimeters

Daily Cover Lv.4

Lv.3

Lv.2

Lv.1

Initial waste layer height = 2.50 m Cover soil layer = 0.30 m

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Sampling, Measurement & Analysis Sample frequency

Gas composition (CH4, CO2, O2, N2) Once a week Leachate (pH, EC, BOD, COD, TOC NH4

+, TKN, NO3, TP) Once a week Gas emission (CH4, CO2) Once a month

Close Flux Chamber Method

Estimation of MCF based on methane ratio in landfill gas

MCF = 1 where %CH4/(%CH4 + %CO2) ≥ 0.6 MCF = [%CH4/(%CH4 + %CO2)]/0.6 where CH4/(%CH4 + %CO2) < 0.6

Gas Emission based on close flux measurement F = ρ VΔC/ AΔt

where F = gas flux, g/m2/h ρ = gas density, g/m3 V = volume of chamber, m3 A = area of chamber, m2 ΔC = gas concentration difference (volume fraction) Δt = time, h

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Variation of rainfall & Settlement Result

Sm I

Sm II

An I

An II

Sett

lem

ent

(cm

.)

Waste Settlement (% From initial height)

Sm I = 35 cm (14 %) Sm II = 30 cm (12 %) An I = 25 cm (10 %) An II = 15 cm ( 6 %)

Cumulative Rainfall = 1,009 L Amount of leachate (% of rainfall)

Sm I = 304 L (30.11%) Sm II = 311 L (30.78%) An I = 301 L (29.82%) An II = 268 L (26.58%)

0

200

400

600

800

1,000

1,200

0 60 120 180 240 300 360 420 480

Cumulat

ive

Rainfa

ll /

Leac

hate

(L)

rainfall

Sm I

Sm II

An I

An II

Time (Days)

0

10

20

30

40

50

60

70

0 60 120 180 240 300 360 420 480

Time (Days)

Rai

nfal

l / d

ay (L

iter)

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Leachate characteristics

0

5,000

10,000

15,000

20,000

25,000

0 60 120 180 240 300 360 420 480

TOC(m

g/l)

Sm I

Sm II

An I

An II

Time (Days)

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

0 60 120 180 240 300 360 420 480

BOD (mg/l)

Sm I

Sm II

An I

An II

Time (Days)

4

5

6

7

8

9

0 60 120 180 240 300 360 420 480

pH Sm I

Sm II

An I

An II

Time (Days)

SMI 90% reduction SMI

An I , An II 90% reduction An I , An II

SMII 90% reduction SMII

Time required to reach 90% degree of leachate stabilization - SM I : 2 months - AN I, II : 6 months - SMII: 8 months

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CH4 content in landfill gas

0

10

20

30

40

50

60

70

0 60 120 180 240 300 360 420 480

Lv.1 Lv.2 Lv.3 Lv.4

CH4(%

v/v)

Time (Days)

SM I

0

10

20

30

40

50

60

70

0 60 120 180 240 300 360 420 480

Time (Days)

Rai

nfal

l / d

ay (L

iter)

0

10

20

30

40

50

60

70

0 60 120 180 240 300 360 420 480

Lv.1 Lv.2 Lv.3 Lv.4

CH4(%

v/v)

Time (Days)

0

10

20

30

40

50

60

70

0 60 120 180 240 300 360 420 480

CH4 CO2 O2

Gas

Com

posi

tion

(%v/

v)

Time (Days)

SM 2 An

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Comparison of CH4 content at mid-depth

0

10

20

30

40

50

60

70

0 60 120 180 240 300 360 420 480

Sm I Sm II An I

(%v/

v)

Time (Days)

Lysimeters Condition MCF based on CH4/(CH4+CO2)

Sm I Semi-aerobic (low compaction) 0.52 Sm II Semi-aerobic

(High compaction) 0.82

An I Anaerobic 0.99

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Gas emission rate & MCF (gas flux based)

Lysimeters Cumulative

CH4 emission (g/m2)

Average emission

(g/m2/kg waste)

Cumulative CO2 emission

(g/m2)

Average emission (g/m2/kg waste)

Relative CH4

emission

Sm I 149 0.20 35,016 47.88 0.5

Sm II 3382 3.83 38,245 43.32 8.6

An I 37,001 43.90 99,783 119.62 98.7

An II 36,480 44.47 95,026 115.84 100

Max ; An II 252 g/m2/d Max ; An II 648.3 g/m2/d

0

50

100

150

200

250

300

0 60 120 180 240 300 360 420 480

Sm I Sm II An I An II

Time (Days)

CH4 Em

ission

(g/

m2 /

d)

0

100

200

300

400

500

600

700

0 30 60 90 120150180210240270300330360390420450480

Sm I Sm II An I An II

Time (Days)

CO2 Em

ission

(g/

m2 /

d)

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Carbon and Nitrogen balance in the lysimeters

Component Sm I Sm II An I An II

Residual 41.70 46.47 56.40 36.61

Leachate 0.01 0.02 0.03 0.04

Gas (CH4) 0.05 1.39 16.60 17.27

Gas (CO2) 6.39 5.76 15.02 13.09

Unaccounted 51.84 46.36 11.96 32.99

Carbon

Nitrogen Component Sm I Sm II An I An II

Residual 8.30 10.22 14.41 8.90

Leachate 4.67 9.04 10.31 10.82

Gas emission & Unaccounted

87.03 80.74 75.29 80.28

Incl. escape of LFG through leachate pipe (for Sm), internal deposition after leachate stagnant & evaporation

Microbial transformation & emission in gaseous form

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Conclusion 1. Semi-aerobic landfill could be implemented successfully in

tropical condition provided that the waste cell was prepared without waste compaction. On the other hand, Semi-aerobic landfill with high compaction behaved like anaerobic landfill in terms of leachate stabilization but produced lower methane emission.

2. Both semi-aerobic Landfill with high and low compaction can decrease gas emission from landfill surface more than 90% when compared to anaerobic landfill.

3. Semi-aerobic landfill with low compaction had their organic substances in leachate reduced by 90% after 2 months, much faster than those in semi-aerobic with high compaction and anaerobic conditions (8 and 6 months).

4. Most importantly, waste density is an important factor governing semi-aerobic condition in tropical landfill

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Future research needs 1. Investigation of optimum aeration rate and operating

condition for inducing natural ventilation into semi-aerobic landfill in tropical climate (wet and dry season).

2. Investigation of possibility to introduce bulking materials or using existing specific waste components in semi-aerobic landfill for promotion of natural ventilation.

3. Investigation of nitrous oxide emission rate and its seasonal variation from semi-aerobic landfill operated in tropical climate.

This research work is carried out under NIES-KMUTT-KU collaboration research laboratory with financial support from

Kasetsart University Research and Development Institute (KURDI)

Acknowledgement

Thank you for your attention