No. Parameter Open Digester Tank Anaerobic Pond

(Lagoon)

Anaerobic Digester

Tank

1 Capital Investment Average Low Average

2 Biogas Capturing Nil Yes Yes

3 Methane Conversion Factor (CH4/m3 POME) Nil 25 28

4 BOD Removal 90% 90% 90-95%

COD Removal 60% 80% 80-90%

5 Biogas Plant Area Requirement Medium High Medium

6 Hydraulic Retention Time (HRT) Long Retention

(Time including

Land application)

45days 18days

7 Operation Uncontrolled Uncontrolled- High

bottom solid build

up & scum forming

Easy to operate,

continuous & non-

stop operation

8 Environment Impact Foul smell Foul smell Moderate

9 Safety Fire Hazard Fire Risk to

membrane

cover system

No leakage of

Biogas