DIPHASIC FIXED-FILM BIOMETHANATION OF DISTILLERY SPENTWASH

Anaerobic treatment of sugarcane molasses-based distillery spentwash h as been investigated employing diphasic fixed-film reactor technology using granular activated carbon (GAG) as support media for microbial a ttachment and growth in the second phase. In the first phase, neutrali zed spentwash was treated with acidogens to produce volatile fatty aci ds (VFA), which are easily utilizable by methanogens to yield methanog ens to yield methane gas. An HRT of 4 days, corresponding to an OLR of 21.3 kg COD m(-3) day(-1) with a COD reduction of 67.1% and gas yield of 0.45 m(3) kg(-1) COD removed with 70% methane content, was achieve d in the methane phase. About 50% reduction in media porosity was obse rved due to accumulation of biomass and inorganics. No apparent inhibi tion of the methanogenic activity was observed even with a propionic a cid concentration of 59.1% (2134 mg l(-1)) of total volatile acids (TV A). Copyright (C) 1996 Elsevier Science Ltd.