Hydrogen and methane production from alcohol wastewater by upflow anaerobic sludge blanket reactors

Abstract

In this work, biohydrogen and methane production from alcohol wastewater using upflow anaerobic sludge blanket reactors (UASB), with a volume of 4 L, was investigated to find optimum conditions. For biohydrogen production, the system was operated at different COD loading rates (23, 31, 46 and 62 kg/m3d) at mesophilic temperature (37 C) and pH 5.5. Seed sludge was pretreated by boiling at 95 C for 15 min before being fed to the UASB system. When the system was operated under the COD loading rate of 46kg/m3d, it provided a hydrogen content of 27%, hydrogen yield of 125.1 ml H2/g COD removed and 95.1 ml H2/g COD applied; hydrogen production rate of 18 l/d; specific hydrogen production rate of 1,080 ml h2/g MLVSS d (4,430 ml H2/L d); and COD removal of 24% For methane production, the effluent from the hydrogen production step operated (at the optimum conditions) was fed into the UASB system at different COD loading rates (4.5, 6.2, 8.8 and 11.6 kg/m3d) without pH control and without recycling to obtain maximum methane production. The maximum methane content (66.41%), methane yield (1,172.96 ml CH4/g COD removed and 581.43 ml CH4/g COD applied), methane production rate (20.37 l/d), specific methane production rate (1,720.32 ml CH4/g MLVSS d and 5,091.91 ml CH4/ L d), and COD removal (50.41%) were alsoobtained at a COD loading rate of 8.8 kg/m3d.