Kinetic Coefficients for the Biological Treatment of Tannery Wastewater Using Activated Sludge Process

Activated sludge process is a highly effective and commonly adapted method of aerobic biological treatment systems and is normally designed on the basis of simplified hydraulic related parameters. Designs of biological treatment systems based on hydraulic considerations are not adequate to ensure efficient operation. This is due to the wide variation in the composition of wastewater and the complex nature of the biochemical reactions occurring in the treatment processes. Hence design of biological treatment systems should be based on the kinetic approach rather than hydraulic parameters considerations. The present study was aimed at developing kinetic coefficients for the treatment of tannery wastewater by activated sludge process. A laboratory scale completely mixed continuous flow reactor was used for the study. The reactor was operated continuously for 86 days by varying detention times from 3 to 9 days. Influent for the reactor was settled tannery wastewater. BOD of the influent and effluent and MLSS of aeration tank were determined at various detention times to generate data for 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 3.125 day, 488 mg/L, 0.64 and 0.035 day-1, respectively. These coefficients may be utilized for the design of activated sludge process facilities for tannery wastewater. Overall BOD removal rate constant ‘K’ was found to be 1.46 day.