1. Closed Anaerobic Digesters Operation for POME Biogas Harnessing
Experience in
Closed Anaerobic Digesters Operation for POME Biogas Harnessing
Under CDM Project By
Ir. RM Subbiah and Tuan Haji Alui Ahmad
Green & Smart Sdn. Bhd.

2. Anaerobic Technology (no air required for microbial survival)

3. Traditionally used A.D. types in POME treatment
Deep open tanks
Deep lagoons
(Biogas released to atmosphere, GHG)

4. OPEN TANK

5. GHG contribute to global warming
POME Biogas contains 45% to 80% methane, which has 21 times higher global warming potential than CO2

6. New AD types used for POME treatment based on “Clean Development Mechanism”
(CDM) principles
Closed lagoon with covering
Closed tanks with stirring
(Biogas harnessed)

7. CLOSED LAGOON

8. Completely Stirred Tank (CST) System
Stir the tank content by:
Using biogas itself
Using stirrers
Using pumps

9. POME – MAS TM
Palm Oil Mill Effluent – Mesophilic Anaerobic System Temperature range 320C – 400C

10. POME-MASTM System

11. System used in 4 Palm Oil Mills Total digesters : 12
Sizes: 1700m3, 2200m3, 3600m3, 5800m3

13. COD Reduction Efficiency
Results
COD Reduction Efficiency
All Digesters
Design
Mill 1
Mill 2
COD Inlet
(mg/L)
55000
Range
42700 – 65940
Mean
55349
54577
COD Outlet (mg/L)
5000
2585 – 4537
3721
2832 – 7690
4421
COD
Reduction
90%
93.22%
90.10%
Feed Quantity
m3/day
120
288

14. Graph Showing Typical Results On Daily Basis
Figure 1: 1700 m3 Anaerobic Digester Monitoring Results

15. Figure 2: 3600 m3 Anaerobic Digester Monitoring Results

16. Reactors are running sustainably for more than 12 months
Longest running > 24 months

17. Biogas production depends on
Effluent flow rate
Incoming COD value
Effluent temperature

18. Typical Values
Mill production: 40T FFB/Hr POME: 24m3/Hr Incoming COD total: 55,000 mg/l
COD reduction efficiency in the digester: 92%
Methane production: 425m3/hr Biogas at 60% CH4 content: 708m3/Hr
Theoretical power generation potential: 1274kW-1558kW

19. COD reduction values measured in POME-MASTM varies from 90% to 95%

20. CH4 (Methane) values measured in POME-MASTM varies from 60% to 75%

21. AT DIFFERENT COD REDUCTION EFFICIENCIES & DIFFERENT METHANE CONTENT
BIOGAS PRODUCTION
AT DIFFERENT COD REDUCTION EFFICIENCIES & DIFFERENT METHANE CONTENT
Mill capacity FFB
m3/hr 40
Effluent Flow rate 24
Inlet COD
Mg/l
55 000
COD reduction efficiency
see table
Assumption : Running on full load on above capacity
1 kg COD reduction gives 0.35m3 Methane
Biogas Production at different methane concentration
Biogas Production at different COD reduction % (m3/hr)
75%
80%
85%
90%
95%
At 55 %
630
672
714
756
798
At 60 %
578
616
655
693
732
At 65 %
533
569
604
640
675
At 70 %
495
528
561
594
627

22. ESTIMATED ELECTRICITY PRODUCTION Electricity Production
COD reduction efficiency
75%
80%
85%
90%
95%
Biogas Production at 60% methane concentration
578
616
655
693
732
Potential electrical power at 2kW* hr/m3 of biogas (kWh)
1156
1232
1310
1386
1464
* Can vary from 1.8kW to 2.3kW per m3 of biogas based on generator efficiency

23. Efficiency Difference - Commercial Value
Every 5% difference in gas production means extra 500,000 kWh/year
@ RM 0.30/kWh = RM 150,000
For 21 years SREP feed in tariff difference in revenue = RM 3.15million

24. Flare CDM compliant GREEN-FLARETM
Exhaust temperature set 6100C maintained at C
Gas retention time about 0.86 seconds

27. Conclusion
POME-MASTM system gives high COD reduction efficiency > 90%
Takes shock loads
CH4 contents 60% to 75% in Biogas
Runs in sustainable manner either on continuous or batch feed mode
GREEN-FLARETM (CDM compliant closed flare)
maintains same set exhaust temperature for different gas flows

28. Thank You Presenter: Ir. RM.Subbiah (012-2181903)
Green & Smart Sdn. Bhd.