Typical process of urban sewage treatment

There are still primary treatment, secondary treatment and advanced treatment in urban sewage treatment processes, but the most popular one at home and abroad is the secondary treatment with the traditional activated sludge method as the core.

The determination of urban sewage treatment technology is based on the requirements of urban water environment quality, incoming water quality, available technology development, urban economic situation and urban management and operation requirements. Before determining the process, it is generally necessary to go through serious investigation and study and economic and technical comparison. In recent years, A-O or A-A-O process, SBR process and oxidation ditch process have been widely used in China. A-O or A-A-O process is also called anoxic-aerobic or anaerobic-anoxic-aerobic process. The development of this process is mainly to meet the needs of nitrogen and phosphorus removal. It is an economical and effective biological ammonia and phosphorus removal technology, which has been adopted by many sewage treatment plants in southern China.

SBR process is also called continuous intermittent activated sludge process. This process structure is mainly a tank with aeration and secondary sedimentation, which is simple in management and especially suitable for urban sewage treatment in small and medium-sized towns. For the continuous operation of a large amount of water, it is generally a joint treatment of several ponds. Oxidation ditch process is an activated sludge process with prolonged aeration. Because of the low load, it has strong impact load, good effluent quality, low and stable sludge output, few structures and simple operation and management. Oxidation ditch can be designed according to nitrogen removal, or it can be slightly modified to remove nitrogen and phosphorus. In addition, there are some varieties of traditional activated sludge process and some process types, such as A-B process.