Pretreatment technology for suspended solids and oil removal in an ethanol fermentation broth from food waste separated by pervaporation process

Ethanol fermentation from food waste decreases pollution and optimizes waste utilization. However, the high-energy consumption involved in the distilling process hinders the industrial application of ethanol fermentation. In the present study, pervaporation was adopted to resolve such a shortcoming. A flocculation–filtration unit was used for the treatment of the fermentation broth. The purpose was to decrease the amount of suspended solids (SS) and oil, which affected the pervaporation membrane used for ethanol separation from food waste broth. Seven kinds of flocculants at three pH levels were adopted to screen the best type and corresponding dosage. Then, a mixture of fiber-ball and quartz sand was used to treat the residue oil and SS. Considering the higher flux of the filtration process, 500 mg/L sodium alginate in a raw fermentation broth was considered the best choice. After treatment, 94.74% of SS and 98.60% of oil in the fermentation liquid were removed. The effluent quality contained the desirable qualities of the inlet water in the pervaporation step.

► We found an effective pretreatment technology for ethanol fermentation liquid.
► We use flocculation–filtration unit to treat the ethanol fermentation broth.
► 500 mg/L sodium alginate was the best flocculant.
► A mixture of fiber-ball and quartz sand was used to treat the residue oil and SS.
► Removal efficiency for SS and oil in the fermentation liquid was 94.74% and 98.60%.