It results in entropHication question with discharging wastewater casually and untreated.A/O process and its transformation processes are the predominant processes now.

• 目前对城市污水的处理多采用A/O工艺及其变形工艺,但是一般A/O工艺存在内回流比高、水力停留时间长、容积利用率低等问题,使得运行费用过高。