Biogas made from high concentrate wastewater in sugarcane and cassava distilleries

The Purpose of this work was to explore upgrade of UASB(Up-flow Anaerobic Sludge Bed)technology, that has been proved inefficient in dealing with high strength organic content wastewater (COD concentration: 20,000-150,000 mg·l^-1) from distillery plants that use cane molasses and cassava as feedstocks in GuangXi Region, China, where sugar and cassava starch are two pillar industries. The limits of UASB reactors was studied under the condition of treating recalcitrant distillery wastewater with low pH, high COD and SO₄ content, and with a very low organic loading rate (OLR 2-5 kg COD.m^-3.d^-1). The enhancement used UASB-TLP (Up-flow Anaerobic Sludge Bed - Turbulent, Laminar, and Pulsation), designed by Able Co., Ltd., based on UASB, including (1) screening optimized populations of anaerobic microbes, and methanogenic bacteria, cellulose- decomposing bacteria, and sulfate reducing bacteria (SRB); (2) redesign of a two-phase fermentation process with a reinforced acidification and pH adjustment in pretreatment; and (3) cultivating granular sludge and maintaining stability within the reactor through a recovery design. In the full scale operation using molasses distillery, the OLR(organic loading rate) was raised to 18-24kg-COD·m^-3·d^-1 and, with COD removal rate of 50-55% (HRT:24-48 h).