Determination of Kinetic Constants for Treating Tannery Wastewater Using Activated Sludge Process (ASP)

Abstract

A study was conducted to evaluate the feasibility of Activated Sludge Process (ASP) for the treatment of tannery wastewater and to develop a simple design criterion under local conditions. A bench scale model comprising of an aeration tank and final clarifier was used for this purpose. The Lab scale reactor was operated continuously and settled tannery wastewater was used as influent to the aeration tank. Five days Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) of the influent and effluent were measured to find process efficiency at various mixed liquor volatile suspended solids (MLVSS) and Hydraulic Detention Time (θ).The results of the study demonstrated that an efficiency of above 90% and 80% for BOD5 and COD, respectively could be obtained if the ASP is operated at an MLVSS concentration of 3500 mg/L keeping an aeration time of 12 hours.ASP is a feasible treatment technology for tannery wastewater treatment, by conducting experiments at the HRTs of 12,10,8,6 and 2 h, it was found that the maximum COD removal efficiency of 84.20% was recorded at 12 h HRT. In this study, the Mathematical Models such as Monod, Grau Second Order, Modified Stover-Kicannon and First Order Kinetic Models were applied for the performance evaluation of the Reactor at any given time and found that the data were in good agreement with the observed ones in the models, such as, Grau second order and Monod. Further, the correlation coefficient value (R2) obtained for the experimental and predicted effluent COD concentration using the above mentioned (Grau second order and Monod) models also confirmed the suitability applying the models to predict the performance of the reactor under lab scale-controlled environmental conditions.