Then, fine mesh processing is carried out to remove small garbage and small gravel.

Then enter the biological reaction stage (secondary treatment), mainly including activated sludge method and biofilm method. Activated sludge process is common and mature. Through microorganisms in activated sludge, organic matter and nitrogen-containing substances in sewage are decomposed and phosphorus-containing substances are aggregated, thus reducing BOD5, total nitrogen and total phosphorus in sewage.

This has basically met the water demand. You can go to Changzhou cursor environmental protection to see.

However, with the increasingly stringent environmental protection requirements, the effluent needs to reach 1 Grade A or above.

It needs to enter the three-stage treatment stage, including chemical treatment, biological treatment and physical and chemical treatment, that is, advanced treatment.

Finally, it enters the disinfection stage, some with chlorine and some with ultraviolet. After disinfection, it will be discharged into the water body or enter the wetland for further treatment.