Ceramic Industry Wastewater Treatment By Chemical Coagulation Process: A Statistical Optimization of Operating Parameters

Abstract

This study deals with chemical oxygen demand (COD) removal from ceramic industry wastewater by chemical coagulation using alum and ferric chloride (FeCl3) as coagulants. The study also focuses on the capillary suction time (CST) of sludge samples which is an important sludge dewatering parameter. Response surface methodology (RSM) approach was employed to evaluate the effects and interactions of the operating variables and to optimize the performance of the process. Significant quadratic polynomial models were obtained (R2 = 96.26% for alum and R2=89.15% for FeCl3 for COD removal;  R2 = 96.6% for alum and R2=90.9% for FeCl3 for CST of sludge, respectively). Alum was more effective coagulant for ceramic industry wastewater treatment as compared with FeCl3. Numerical optimization based on desirability function was employed; in a 36 min trial 95.2% of COD removal was achieved at alum dosage of 3.3 g/L and pH 5. The optimization study shows that the minimum CST of sludge was found 17.4 s at alum dosage of 5 g/L and pH 5 in a reaction time of 16 min. The results indicate that the RSM is suitable for the design and optimization of chemical coagulation process using alum as a coagulant fort he treatment of ceramic industry wastewater.