Environmental Engineering

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Browsing Environmental Engineering by Author "Afera, Goitom(PhD)"

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    Determination of Biokinetic Coefficients of Distillery Wastewater Using Activated Sludge Process
    (Addis Ababa University, 2015-07) Werku, Teshome; Afera, Goitom(PhD)
    Distilleries are among the existing industry which produces high effluent volume characterized with high temperature, low PH, very high COD and BOD, which is potentially dangerous to the environment if it is discharged without effective treatment. Therefore, this study is conducted to determine kinetic data which is crucial for effective treatment of this high volume distillery effluent using activated sludge process. In this thesis work samples for the laboratory experiment were taken from Metehara sugar factory, with the following characteristic pH 3.8 – 4.5, COD 92,000 mg/L, BOD 45,410 mg/L, TS 49,950 mg/L, temperature 89 – 98 oC , Nitrogen 1150 mg/L and phosphorous 4100mg/L. In the determination of the kinetic coefficients, Michaelis-Menten relation for continuous process was used. Chemicals which are used in this experiment are ATH to avoid nitrification, KOH to absorb CO2and Na (OH) to maintain pH. During the study, performance of a laboratory-scale biological treatment unit for the distillery waste was evaluated and the kinetic parameters for the activated sludge process were determined. A laboratory-scale treatment unit comprising aerobic digester and final clarifier was used for this purpose. The treatment unit was operated continuously for 270 days by varying the hydraulic retention times from 2 to 9 days. The biological oxygen demand (BOD) of the influent and effluent and the mixed liquor volatile suspended solids of the aeration tank were determined at various detention times to generate data for the kinetic coefficients. The kinetic coefficients k (maximum substrate utilization rate), Ks(half velocity constant), Y (cell yield coefficient), and Kd (decay coefficient) were found to be 4.46 per day, 534 mg/L, 0.714, and 0.038 per day, respectively, based on BOD and MLVSS in the reactor. These coefficients used for the design of reactor volume and sludge handling facility for activated sludge process