Sewage treatment (wastewater treatment) is a process to make sewage meet the water quality requirements for discharge or reuse, and to purify it. Sewage treatment is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical treatment, catering and other fields, and it has also entered the daily life of ordinary people more and more. The upstream suppliers of sewage treatment industry are mainly sewage treatment equipment manufacturers and sewage treatment chemicals suppliers. All belong to industries with fast development and good demand. The topic of water pollution is constantly being raised, especially groundwater pollution. In Hangzhou, Zhejiang, Wenzhou and other places, farmers or entrepreneurs invited environmental protection directors to swim in the river to arouse people's attention to the seriousness of water pollution. Although all environmental protection directors have chosen silence or refusal, people's awareness of environmental protection has awakened and their concern for water pollution has reached an unprecedented level.