There are two domestic companies specializing in R&D and water treatment equipment sales. One is Shanghai Andingji Water Treatment Company, relying on Tongji University. There are many water treatment products in the company, among which the "mobile washing vertical filter" specially used for sewage treatment is advanced in technology and has won many national innovative patents. Advanced and mature technology, widely used. The other is Puhua Water, relying on Tsinghua University, specializing in rotary fiber filters. This product is a model of foreign technology. Relatively speaking, the products of Anjingji Company are cheap and advanced in technology. Because its products were launched after Puhua, it overcame many shortcomings of Puhua products.