Please refer to the principle and process of CAST sewage treatment.

In the whole process of CAST, the biodegradation of organic pollutants and mud-water separation are completed in one reactor. The reactor is divided into three zones, namely, biological selection zone, facultative zone and main reaction zone. The biological selection zone operates under anaerobic and facultative conditions, which makes the sewage contact with the returned sludge, makes full use of the rapid adsorption of activated sludge to accelerate the removal of soluble substrates, and plays the role of acidification and hydrolysis of refractory organic matter, and at the same time can effectively release excessive phosphorus adsorbed in the sludge under anaerobic conditions. The facultative zone mainly removes organic matter by adsorption of regenerated sludge, promotes further release of phosphorus and strengthens nitrification/denitrification of nitrogen, and can also restore sludge activity by aeration and idleness.

Schematic diagram of casting cycle flow

-Installing an adsorption selector in the tank to prevent sludge bulking;

-Excessive biological phosphorus removal can be realized, and the process is optimized in the system;

-Simultaneous nitrification/denitrification can be realized, and total nitrogen in sewage can be removed;

-Biological process and mud-water separation process are carried out in the same tank, and there is no need to set up a primary sedimentation tank and a secondary sedimentation tank;

-The operation of CAST process system is simple and clear;

-Flexible operation, when hydraulic shock load occurs, it can be buffered only by changing the operation cycle;

-The capital construction cost is low, and the tank volume is smaller than the sum of the primary sedimentation tank, aeration tank and secondary sedimentation tank in the traditional activated sludge process;

-The treated effluent can meet the water quality requirements of Takaizumi without sand filter or flocculation filter.