A systematic and critical review of two decades’ application of response surface methodology in biological wastewater treatment processes

Response surface methodology (RSM) has been applied to design experiments, analyze operative parameters, produce models, and optimize operational conditions in water and wastewater treatment processes.Although various aspects of RSM application in physicochemical wastewater treatment processes have been scrutinized, the biological processes are considered more efficient methods for wastewater treatment.Thus, evaluation of RSM application in biological processes would be useful research to reduce costs and number of experiments in biological treatment processes as well as to achieve its milestones in future studies.In this study, a thorough systematic and critical review evaluated two decades of RSM application in conventional biological treatment processes, including aerobic, anaerobic, anoxic, combined, and lagoon processes, to clarify its limitations and suggest crucial enhancements for future studies.