Suzhou Industrial Park, the second wastewater treatment plant using multi-point inlet inverted A/A / O biological phosphorus denitrification activated sludge process, and in the aeration process introduced into the U.S. Biochemical Technology Corporation Biological Intelligent Optimization System (BIOS system), in order to achieve energy saving and reduce consumption. The effluent water quality indicators are implemented in the Taihu Lake Basin standards, and a 20,000 tons / day water reuse system is constructed simultaneously.