Comparing the use of common bean extracted natural coagulants with centrifugation in the treatment of distillery wastewaters

Distillery spent washes are highly polluted wastewaters. Pollution caused by them is one of the most critical environmental issue. In this study, the coagulation efficiency of common bean extract in treatment of different distillery wastewaters was investigated. Active components were extracted from 10 g/l of ground sample with 0.5 mol/l NaCl. Obtained coagulant was used for organic matter removal from wastewaters remained after bioethanol production on intermediate products of sugar production-extraction juice, thin juice and thick juice, and by-product-molasses, as nutrient mediums. The coagulation efficiency was assessed by jar test, and organic matter decrease was calculated based on COD measurements. The experiments confirmed that common bean extracted natural coagulant could be used successfully in distillery wastewater treatment. The best achieved efficiencies of organic matter removal were 68.8% for extraction juice wastewater, at pH 8.50 with coagulant dose of 5 ml/l, and 60% for molasses wastewater. at the original pH of this stillage (5.40) with the same dose. Better organic matter removal from thin and thick juice wastewaters were achieved by centrifugation.