Improving wastewater treatment plant performance based on effluent quality, operational costs, and reliability using control strategies for water and sludge lines

Abstract

As a result of urbanization and population growth, wastewater treatment plants (WWTPs) are experiencing increased influent flow rates, pollutant loads, and stricter standards for effluent quality. Therefore, implementing a control strategy is critical for improving the performance of WWTPs in response to highly variable effluent quality. In this study, different strategies for both water and sludge lines are deployed in WWTP model to control dissolved oxygen and biomass concentration in activated sludge system by manipulating aeration intensity and sludge flow rates. The efficiency of suggested control strategies is evaluated using different performance criteria, including effluent quality indicators, operational costs, and system reliability. The proposed method is applied in a real WWTP located in south of Tehran, the capital of Iran. According to the findings, controlling aeration system and sludge flow rate improve effluent quality and system reliability despite increasing operational costs. In the case of simultaneous control of water and sludge lines, the effluent quality index has improved by 9.3%, while the operational costs have increased by 1%. Moreover, the system reliability based on effluent ammonia, TSS, and COD concentration have increased by 33.4%, 9%, and 12.2%, respectively.