Enhancement of separate hydrogen and methane production from ethanol wastewater by Microaeration

Abstract

The objective of this research was to examine the effects of micro aeration on the separate hydrogen and methane production from ethanol wastewater using a two-stage up flow anaerobic sludge blanket reactor (UASB) system, with recycle ratio of 1:1 (methane effluent flow rate: feed flow rate) under mesophilic temperature, with and without pH control at 5.5 in hydrogen and methane production tank, respectively. The results showed that, under optimum COD loading rate of 6.0 kg/m3 d based on the methane UASB volume (36.0 kg/m3 d based on the hydrogen UASB volume), the methane UASB unit had the highest process performance in terms of COD removal of 55%, a gas production rate of 27.5 l/d, CH4 content of 74% and a methane yield of 66.6 l/g COD applied. Under optimum COD loading rate (6 kg/m3 d base on methane UASB tank) with the optimum oxygen supply load (4 ml O2/LR d), the methane production performance (COD removal of 62.5%, a gas production rate of 45.5. l/d, CH4 content of 75% and a methane yield of 191.8 l/g COD applied) was maximized. Furthermore, the H2S in the produced gas was totally removed from the methane USB unit.