ABSTRACT
The flow diagram of a modified A2/O process has been shown in Figure 1. The system consists of a preanoxic zone, anaerobic zone, anoxic zone, and oxic zone followed sequentially. Experimental device is made up of a steel plate. The designed influent rate was 0.5 m3/h. The main designed parameters are as
follows: The retention time of preanoxic zone was 0.5 h, anaerobic zone was 1 h, anoxic zone was 2 h, and aerobic zone was 5 h; the influent distributive ratio to preanoxic zone/anaerobic zone was 1:9. The dissolved oxygen (DO) in anaerobic zone was less than 0.2 mg/L, in anoxic zone was 0.2-0.5 mg/L, and in aerobic zone was 2.5-3.5 mg/L.
