Study on Start-up Process of UASB Reactor For Treating Cellulosic Ethanol Wastewater

Taking treatment of cellulosic ethanol wastewater by UASB reactor as a researching object,the start-up process of UASB reactor was analyzed and discussed. The results show that,taking anaerobic digestion sludge from urban sewage treatment plants as started sludge,under the effective volumetric loading rate 0.33~1.11 kg COD/(m3.d) conditions,the UASB reactor can be successfully started,and COD removal efficiency can reach more than 70%. At the initial period of start-up,the effluent pH value is significantly higher than the influent pH value,and the sludge decreases at the beginning and then increases. As the concentration of SO4 2- is increased to 7 250 mg/L and COD/SO4 2-ratio is 2.7:1,UASB treatment system for cellulosic ethanol wastewater will collapse. As the UASB reactor is in stable operation,the sludge concentration increases to 30~40 g/L,MLVSS/MLSS ratio reaches about 90%.Under the conditions of HRT 14~41 h,reflux ratio of 3:1 to 13:1 and effective volumetric loading rate 3.45~14.67 kg COD/(m3.d),UASB reactor can maintain more than 90% COD removal rate for cellulosic ethanol wastewater,effluent COD is less than 1000 mg/L.