Optimization of air flowrate under different control strategies focus on biological process in wastewater treatment plant

To optimize energy consumption is one of the major issues in wastewater treatment while maintaining effluent water quality standards. Aeration in biological processes requires more energy in wastewater treatment plants than other processes. In this study, simulations were conducted by using the ASM2d module of GPS-X. Several control strategies-namely, on/off dissolved oxygen control, proportional (P) / integral (I) dissolved oxygen control, and cascade ammonia control-are performed in biological processes to confirm the effects of ammonia reduction and optimize energy cost. According to the results of cascade control, it is 23 % smaller than the original energy cost. Sensitivity analysis was further proceeded to confirm the influence of tuning parameters, namely, proportional and integral gains. Consequently, proportional gain improves response speed and controls system accuracy. Integral gain is effective in decreasing the steady-state error of the system. The optimized values of proportional and integral gains lead to the best performance of aeration and provides a reference for first-phase plant operation.