Abstract: With the development of the city, environmental protection requirements are increasingly strict, and the problem of sewer sludge outlet has gradually attracted the attention of the management department, and has also become a problem faced by the city. A number of sewage sludge treatment stations in China were investigated and their processes and existing problems were analyzed. On this basis, a sewage sludge treatment station in Wuhan was taken as an example, and combined with the characteristics of the project, the combined treatment process of “pretreatment + multistage separation + mechanical dehydration”, which has little influence on the downstream sewage treatment plant, was adopted. After treated, four types of residues were generated: bricks, stones, tree roots, plastics, etc., with a particle size greater than 100.0 mm; stones, plastics, scum, etc., with a particle size between 3.0 and 100.0 mm (not including 100.0 mm) and a moisture content of 11.4%; sand, organic matter, etc., with a particle size between 0.2 and 3.0 mm (not including 3.0 mm) and a moisture content of 21.8%; and silt with a particle size smaller than 0.2 mm and a moisture content of 25.7%. The unit operation cost in the station was 75.53 yuan/t according to the calculation of full load operation. At the same time, the problems existed since the operation were summarized in order to provide reference for the subsequent sewage sludge treatment projects.

Key words: sewer sludge, multistage separation, mechanical dehydration