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Abstract
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Ethanol manufacture from molasses generates large volumes of high strength wastewater that is of serious environmental concern. An average molasses based distillery generates 15 L of spent wash per1 L of alcohol produced. The effluent is characterized by extremely high chemical oxygen demand (COD) (80,000-100,000 mg/L) and biochemical oxygen demand (BOD) (40,000-50,000 mg/L), apart from low pH, strong odor and dark brown color. Distillery wastewater also contains nutrients in the form of nitrogen (1660-4200mg/L), phosphorus (225-3038 mg/L) and potassium (9600-17,475 mg/L) that can lead to eutrophi- cation of water bodies. Further, its dark color hinders photosynthesis by blocking sunlight and is therefore deleterious to aquatic life. Adequate treatment is therefore imperative before the effluent is discharged. Chemical treatment systems are not economic; therefore a combination of biological and chemical method is needed. The most important fraction of pollutants can be eliminated by biological methods. The aim of this work was to study COD removal and decolorizing using integrated anaerobic/aerobic biological oxidation and ozonation of distillery wastewater.
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