REDUCING ENERGY AND CHEMICALS CONSUMPTION OF WASTEWATER TREATMENT PLANTS BY ACCURATE AERATION CONTROL: A CASE STUDY

As the main energy consumer in wastewater treatment plants(WWTPs), aeration system has a high potential for energy saving. In this study, an air distribution and control system was introduced into Zhangcunhe WWTP, Qingdao. The efficiency of this system was tested, and its effects on the effluent quality and energy consumption were investigated. The results showed that the dissolved oxygen(DO) concentration in the aeration tank could be maintained within ±0.3 mg/L of the setpoint for longer than two-thirds of the running time. By applying the accurate aeration control, the average concentration of effluent chemical oxygen demand(COD) decreased from 19.6 mg/L to 16.7 mg/L, while those of ammonium and total nitrogen(TN) decreased from 0.37 mg/L to 0.28 mg/L, and from 8.48 mg/L to 7.36 mg/L, respectively. The proportion of days with effluent TN<10 mg/L increased from 79% to 100%, indicating a more stable effluent quality. Besides, the power consumption of the aeration system was reduced by 24.8% while the sodium acetate dosing decreased by 15.1%. Therefore, accurate aeration control is an effective approach to reduce the energy and chemical consumption of WWTPs.