Activated sludge treatment of sewage can be divided into two methods: intermittent treatment and activated sludge treatment.

Sewage treatment by activated sludge method can be divided into traditional method and batch method.

1 traditional activated sludge process

Advantages: ① The BOD removal rate of wastewater unsuitable for physical and chemical treatment can reach above 95%. ② The construction investment is high, but the treatment power cost is low.

Disadvantages: the required stay time is long, the equipment is huge, and the capital investment is large. It is necessary to add various structures to increase the volume of various structures, thus increasing the area of the treatment plant and increasing the management personnel and management difficulty.

Development direction: ① In order to make the composition and concentration of wastewater system uniform, re-evaluate the pretreatment and re-study the regulating tank. ② Discussion on strain selection of activated sludge microbial system. ③ Introduce instruments and management indicators into activated sludge process equipment.

Two-batch activated sludge process

In recent years, with the continuous expansion of urban scale and the development of towns themselves, sewer facilities have shown a trend of turning from big cities to small and medium-sized cities and rural towns, and small sewage treatment facilities have gradually increased, making it more and more urgent for rural towns to improve their living environment.

Compared with large sewage treatment facilities, small sewage treatment facilities have different natural and social conditions. Therefore, it is necessary to study and adopt small sewage treatment facilities to replace the large-scale treatment methods in the past. Small sewage treatment should have the following characteristics: ① easy to operate and manage; ② Convenient maintenance; ③ Low construction cost; ④ The effluent quality is good. After years of practice in some sewage treatment plants at home and abroad (such as Dayuanmachi Sewage Treatment Plant in Chiba Prefecture, Japan, etc.). ), which proves that the intermittent activated sludge process is a treatment method that can meet these conditions.

The intermittent activated sludge process uses the treatment tank to aerate, precipitate and discharge the treated water, which simplifies and miniaturizes the equipment, has clear flow pattern in the tank, is convenient for operation and management, can realize unattended operation, has buffering capacity for the load change of influent sewage, has stable treatment performance, can not only remove organic matter and suspended matter, but also has good denitrification effect. Batch activated sludge process is a typical method. Generally, two aeration sedimentation tanks are set to continuously enter the mixed sewage. Each tank is staggered for half a period, and the operation period is 6 hours, which is repeated.