In-ground covered biogas digester (CGR)

The covered biogas digester, also called a CH4 generating reactor, is a low-rate anaerobic reactor built in the ground. It treats wastewater and slurries of moderate to very high organic strength and produces biogas as the energy product.

It is suited to palm-oil mill effluent, distillery and sugar wastes, starch streams, animal manure, and food-processing organics. Because the reactor is in the ground it tolerates solids and shock loads better than a small high-rate tank, and it costs less to build where there is room for it. Downstream aerobic treatment still has to meet the discharge limit. This page does not make the digester a certified emissions reduction.

See also biogas, wastewater treatment, and hydrogen sulfide scrubbers.