EFFECT OF CO₂ CONCENTRATION IN THE DIGESTER GAS ON ANAEROBICSEWAGE SLUDGE DIGESTION

Abstract

Anaerobic digestion is an important process in the sewage sludge treatment systemby reason of sludge solid reduction, stabilization, and producing methane gas which is used asenergy source. This paper shows the result of basic study on CO₂ concentration control in thedigester gas for increasing methane gas production in the anaerobic digestion process ofsewage sludge.
The methane gas production increased at a rate of approximately 30-% in comparison withthat of the conventional process by controlling CO₂ concentration in the digester gas to 50 to60 v/v-%. It was supposed that the increasing of methane gas production was might be relatedto the acceleration of the biological decomposition of hardly decomposable carbohydrates inthe feeding sewage sludge, and to the existence of the biological oxidation-reduction reactionof sulfides in the sewage sludge digestion.