Anaerobic treatment of blended sugar industry and ethanol distillery wastewater through biphasic high rate reactor

ABSTRACT

This study aimed to investigate the physicochemical properties of sugar industry and ethanol distillery wastewater and the treatment of the blended wastewater through a two-stage anaerobic reactor. For this treatment, different initial chemical oxygen demand (COD) concentrations (5–20 g/L) and hydraulic retention times (HRTs) (2–10 days) were applied. The sugar industry effluent characteristics obtained in terms of organic matter (mg/L) were as follows: 5 days biochemical oxygen demand (BOD₅): 654.5–1,968; COD: 1,100–2,148.9; total solids (TS): 2,467–4,012 mg/L; and pH: 6.93–8.43. The ethanol distillery spent wash strengths obtained were: BOD₅: 27,600–42,921 mg/L; COD: 126,000–167,534 mg/L; TS: 140,160–170,000 mg/L; and pH: 3.9–4.2. Maximum COD removal of 65% was obtained at optimum condition (initial COD concentration of 10 g/L and HRT of 10 days), and maximum color removal of 79% was recorded under similar treatment conditions. Hence, the performance of the two-stage anaerobic reactor for simultaneous removal of COD and color from high-strength blended wastewater is promising for scaling up in order to mitigate environmental problems of untreated effluent discharge.

KEYWORDS:

• Wastewater
• treatment
• anaerobic reactor
• chemical oxygen demand
• organic matter
• color
• sugar industry
• ethanol distillery

Acknowledgments

We would like to thank the Ethiopian Institute of Water Resources, Addis Ababa University, for supervising financial support given by the United States Agency for International Development (USAID) under the USAID/HED grant in the Africa-US Higher Education Initiative – HED 052-9740-ETH-11-01. We would also like to thank Ghent University, Faculty of Bioscience Engineering, and Addis Ababa Science and Technology University for offering us laboratory facilities and services, and the Ethiopian Sugar Corporation Research and Development Center (Wonji) for providing us sugar industry and ethanol distillery wastewater and all other necessary support such as information, transportation service, and professional assistance.