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 C for 5 days in molasses pigments medium containing glucose 3.0%, yeast extract 0.5%, KH2PO4 0.1% and MgSO4 Æ 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 Æ 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%.