Performance evaluation of column-SBR in paper and pulp wastewater treatment: optimization and bio-kinetics

Pulp and paper industry generates effluent containing harmful compounds like chlorophenols which are difficult to biodegrade. It requires an appropriate treatment in order to meet the stringent discharge standards. In this work, a bench scale column type sequential batch reactor (SBR) was employed for treating pulp and paper wastewater. The performance of SBR, seeded with acclimatized sludge was optimized and analysed for maximizing COD and AOX removal. The process parameters viz; pH, initial COD, cycle time and MLSS were optimized and their effects on response variables: COD removal efficiency, AOX removal efficiency and SVI were investigated. The optimum conditions were determined to be: initial COD 1200 mg/l, pH 7.5, MLSS 2100 mg/L and cycle time 15 h, for 73.2% COD removal, 57.6% AOX removal and 122.8 mL/g SVI. The complex compounds were broken down into numerous intermediate compounds thus enhancing COD and AOX removal with low SVI. The bio-kinetics of the optimized system was also analyzed in order to understand the bacterial nature towards substrate utilization. Two kinetic models namely Grau second-order model and Stover-Kincannon model were found to be fitwell with high correlation coefficients (R-2 = 0.99) for COD as well as AOX.