The pretreatment of yeast wastewater were studied by activated sludge flocculation combined with Ca(OH)2 flocculation in this paper. The results showed that activated sludge flocculation played a role in regulating pH and diluting influent concentration. Ca(OH)2 flocculation can regulate pH (from 3.84 to 7.30) and remove SO42- (23.5%~30.1%). The best Ca(OH)2 dosage was 1.0 g/L, with which the sulfate can be reduced to 29.1%.
