Fiber carrier A²/O process treating domestic wastewater and denitrifying phosphorus removal efficiency

Fiber carrier A²/O process is developed by adding polyvinyl alcohol fiber to the anaerobic, anoxic and aerobic tank in a A²/O process by combining biofilm approach into conventional activated sludge process to constitute a new system. Fiber carrier A²/O process was compared with traditional A²/O process for domestic wastewater treatment, and the effect of different nitrification liquid reflux ratio on denitrifying phosphorus removal was studied. Results show that the fiber carrier A²/O process has obvious advantages. The COD and ammonia removal rate reached 92.5% and 93.1%, respectively. Though increasing the nitrification liquid reflux ratio can make the DNPAOs enrich on the carrier. When reflux ratio was increased to 300%, the amount of phosphorus absorption was 26. 28 mg·L^-1 and the maximum utilization of PHB was 1.32 g·g^-1·L^-1 and had the best metabolic activity. The system of fiber carrier A²/O was proved to have significant denitrifying phosphorus removal capacity.