Quality analysis and pretreatment of cellulosic ethanol wastewater

The quality of the wastewater from the equipment of COFCO's cellulosic ethanol was analyzed and it was determined that the suspended solid was high to 123868 mg/L, meanwhile COD_Cr was over 12000 mg/L. At least 52 kinds of organic compounds were detected according to the GC-MS analysis and acetic acid as high as 29188 mg/L was found, which was dominated in the volatile fatty acids(VFAs) in the wastewater. Taking COD_Cr removal rate, liquid yield after pretreatment for SS removal, treatment rate and energy consumption per unit volume as evaluation parameters, three physical pretreatment methods for suspended solid removal was tested, including natural subsidence(NS), centrifugation separation(CS), plate and frame filter press method in laboratory scale. Results show that the SS removal rate is 66.44% for plate and frame filter-press filtration and COD removal rate can reach 64.75%. The plate and frame filter press method is also predominant in the treatment rate(0.6 h/L) and energy consumption per unit(0.22(kW · h)/L). Most of the conventional water quality indicators and the ion concentration decrease significantly with the solid-liquid separation.