Abstract
Pulp and paper mill wastewater treatment poses a significant challenge due to the presence of numerous refractory pollutants, necessitating the need for effective treatment methods. This study aims at multiobjective optimization of an anaerobic baffled reactor (ABR) combined with an activated sludge reactor (ASR) for pulp and paper wastewater treatment. The optimization approach minimizes the hydraulic retention time (HRT) while maximizing the ABR system's organic loading rate (OLR) and COD and BOD removal efficiency. Optimization efforts identified the optimum conditions for the ABR as an OLR of 6.2 g/L/d and an HRT of 3.2 d. Under these conditions, the remarkable COD removal efficiency of 92% and BOD removal efficiency of 95% were achieved in the ABR, demonstrating the system's robust performance in reducing the pollutant load of the wastewater. The integrated ABR-ASR also exhibited outstanding removal efficiencies for various parameters in the optimum conditions. Specifically, COD, BOD, TSS, turbidity, and color displayed removal efficiencies of 95%, 97%, 92%, 98%, and 92%, respectively. These findings underscore the versatility of the integrated system in addressing a spectrum of pollutants present in pulp and paper wastewater. Furthermore, the rate of substrate consumption was investigated using the modified Stover-Kincannon model. The saturation value constant (KB) and the maximum utilization rate (Umax) values for ABR were found to be 7.95 g/L/d and 5.5 g/L/d, respectively, while for ASR, these values were 0.69 g/L/d and 0.15 g/L/d. This research advances our understanding of the synergistic potential of the ABR-ASR in treating high-strength industrial wastewater.