Optimization of operating process was triggered by a saltation of ratio in a full-scale activated sludge system

Chemical additions and energy costs in the wastewater industry are increasing trends in more stringent requirements for effluent quality and electricity rates. A novel ratio of chemical P removal addition to influent total phosphorus (TP) is proposed with an application to optimize operation for saving running costs. For this purpose, we monitored the performance of the process for a consecutive year (2018) and established a dynamic model related to the process. The main process variables included the concentration of influent and effluent quantity, chemical oxygen demand, biochemical oxygen demand, total nitrogen, TP, and dosing chemical additions. The ratio of the average daily effective mass of Fe (M Fe-d ) to the average daily mass of influent TP (TP Inf-Tot-d ) was found sharply rise to 3.3 g/g or higher in summer and autumn, whereas it smoothly dropped to about 2.3 g/g in winter and spring. This phenomenon can account for enhanced biological phosphorus removal and upset. The emulating results showed that the proposed indicator can provide a relatively accurate representation of the system dynamics while significantly reducing the chemical additions and energy compared to a model that simulates the entire process without a complicated control system and algorithm.