Aerobic/anaerobic sludge digestion process

摘要

A process for digestion of sludge wherein the sludge is oxygenated in a first digestion zone at temperature of from 35° to 75° C. to partially reduce the biodegradable volatile suspended solids content of the sludge. The partially stabilized sludge is anaerobically digested in a covered second digestion zone at temperature of from 25° to 60° C. to further reduce the biodegradable volatile suspended solids content of the sludge, to less than about 40% of the biodegradable volatile suspended solids content of the sludge introduced to the first digestion zone.