Untitled Palm Oil Mill Effluent

Palm Oil Mill Effluent (POME) is a useful source of significant biogas. However few mills can make full use of the biogas produced, and may be far from a grid or other electricity users.

There are technical problems that must be addressed:

•  Sedimentation and scum, if not managed, will accumulate
•  High COD can cause toxic acid formation and digester failure
•  There can be significant variation in biogas composition
•  Mills have a stop-start operation with peak loads

Biogas potential varies. Main factors are region, average freshness of fruit, efficiency of oil extraction at mill, process configuration, use of decanters or nozzle centrifuges, extent of pressing of EFB, use of water in mill to assist oil extraction

KPSR designs are ideally suited to POME biogas projects.

“At a palm oil mill waste pond somewhere in Indonesia”

Cassava waste water has is readily acidified, and care must be taken to avoid low pH conditions. The waste COD may be relatively dilute, and wash-out of active biomass is to be avoided.

In-ground reactors do not require chemical addition for pH balancing, and can process suspended solids. They achieve significantly higher gas overall output than UASB designs.

Factories may add additional acid from burnt sulphur or sodium metabisulphite. Modified starch processes may add additional chemicals.

Root pulp may be digested to increase the gas output and balance load. Root pulp may also be stored.

Distillery Waste

Molasses distillery waste has high COD, some of which is unable to be digested. High sulphate levels lead to high H2S in the gas.  Care must be taken with loading rates. Longer residence times assist  degradation of slow-to digest components.

Biogas produced is usually sufficient to generate 100% of the process steam requirement.

Irrigation of the treated waste to cane fields is recommended.