Decolorization of molasses wastewater by a strain No.BP103 of acetogenic bacteria.

Among 170 strains of acetogenic bacteria, a strain No.BP103 showed the highest decolorization yield (76.4+/-3.2%) when cultivated at 30 degrees C for 5 days in molasses pigments medium containing glucose 3.0%, yeast extract 0.5%, KH2PO4 0.1% and MgSO4 x 7H2O 0.05% and the pH adjusted to 6.0. In addition this strain could decolorize 32.3+/-3.2% and 73.5+/-3.5% of molasses pigments in stillage and anaerobically treated molasses wastewater, both supplementing glucose 3.0%, yeast extract 0.5%, KH2PO4 0.1% and MgSO4 x 7H2O 0.05%. However without nutrients supplement, the decolorization yields were 9.75+/-3.0% and 44.36+/-3.4%, respectively. In a replacement culture system involving six times replacement (30 days), the strain No.BP103 showed a constant decolorization yield of 72.0+/-3.2-84.0+/-3.2% and caused decreases of biological oxygen demand and chemical oxygen demand values of approximately 58.5+/-6.4-82.2+/-7.1% and 35.5+/-0.42-71.20.58%, respectively. Under a periodical feeding system, the decolorization yield was 30.0+/-2.1-45.0+/-3.5%.