Decolorization of Distillery Spentwash (Melanoidin) by Immobilized Consortium (Bacterium and Yeast) Cell: Entrapped into Sodium Alginate Bead

摘要

Sugarcane distilleries use molasses for ethanol production and generate large volume of effluent containing high Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) along with melanoidin pigment. The aim of this study was to isolate potential thermotolerant melanoidin decolorizing bacterium and yeast from natural resources for consortium development and entrapped in suitable matrix for immobilization at large scale spentwash treatment. A total 58 bacteria and 24 yeast were isolated from soil sample of distillery site in which Pediococcus acidilactici B-25 and Candida tropicalis RG-09 showed higher decolorization. These two strains were used for consortium development and then entrapped in sodium alginate for the wastewater treatment in a continuous column immobilization system. The immobilized consortium cells showed maximum 85% decolorization with the optimized parameters such as 2% (w/v) sodium alginate, 2% (w/v) calcium chloride with 16 h curing time, 5 g alginate beads with 2 mm bead diameter. The immobilized cells of consortium in alginate beads are more efficient for the wastewater treatment and can be reused for eighteen cycles (24x18 = 432 h) without any loss in their activity and 22 cycles with 72% residual activity. Immobilization of consortium cells in continuous column system is better than free culture. Among the immobilized cell bioreactors, no doubt that continuous column immobilization is a novel and efficient one which can be adopted for the treatment of industrial wastewater containing melanoidin compounds and other pollutants. A proper choice of immobilized culture, careful consideration of various design parameters for continuous column immobilization will make treatment process cost effective in the long run.