What are some challenges faced by current China's municipal sludge treatment industry?

According to data from the E20 Environmental Research Institute, China's municipal sludge production in 2021 is initially calculated to be 55.52 million tons, an increase of 8.23% over 2020. Among them, domestic sewage is one of the main sources of municipal sludge. In recent years, the annual increase in municipal sludge production is also closely related to the rapid increase in domestic sewage production.

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The sludge generated after domestic sewage treatment is a result of the enrichment and concentration of pollutants in sewage. The "Technical Guidelines for Sludge Treatment and Disposal of Urban Domestic Sewage Treatment Plants (Trial)" issued by Sichuan Province once addressed the problem of sludge generated by domestic sewage. 

The documents show that sludge disposal methods include sludge incineration and sludge landfill treatment. In sludge transportation, the use of pipelines closed vehicles, and closed barges to transport sludge is encouraged. The whole process should be monitored and managed during transportation to prevent secondary pollution of the environment caused by exposure, spilling, or dripping.  Moreover, the document also puts forward clear guidelines on technical routes such as sludge dewatering, lime stabilization, sludge thermal drying, and anaerobic digestion, so that municipal sludge can be disposed of in a standardized manner.

A few days ago, Wuhan in Hubei province issued a "Special Plan for the Treatment and Disposal of Urban Sludge in Wuhan City (2021-2023)" (to stop soliciting opinions on August 5). It is predicted that in 2035, the sludge volume of the city's sewage treatment plants will be 8,846.8 tons/day (with a moisture content of 80%). In the future, a sludge treatment and disposal pattern of "incineration as the mainstay and comprehensive utilization as a supplement" will be formed to create "1 separate incineration + 9" and "Coordinated incineration + N comprehensive utilization" system layout. Through the newly built Beihu Sludge Treatment and Disposal Plant, the Xinzhou Renewable Resources Comprehensive Treatment Base Waste Co-incineration Project, and the Zuoling Gehua Circular Economy Industrial Park Sludge Project, 4 pipeline culverts including Yangluo, Dongxihu, Hanyang, and Zuoling have been built, which means the sludge treatment station will increase the scale of municipal sludge treatment and disposal.

As an important development link, all regions have set "time-limited tasks" for sludge treatment and disposal. With the deadline of 2025, Chongqing City proposes the goal of basically achieving 100% of the urban domestic sludge's innocuous treatment and disposal rate. Jiangsu Province has established a preliminary sludge disposal safety system, and Hunan Province stated that the urban sludge's innocuous disposal rate is to achieve more than 93%.

This is just the first step in dealing with municipal sludge, with harmless use, reduction, and resource utilization being the final goals.