Analysis of sludge treatment and disposal status at home and abroad

Let's first understand the current situation and development trend of sludge treatment and disposal in foreign countries.

For developed countries, sludge treatment and disposal technology has been relatively mature, and relevant laws, regulations and standards are relatively perfect.

Because the first way to treat sludge in Europe was landfill and land use. In the 1990s, there were fewer and fewer sites available for landfill sludge, and the pressure of sludge treatment and disposal was also increasing, so the construction of sludge drying and incineration facilities began in Europe. Drying incineration can not only kill the harmful components in sludge, but also reuse the burned sludge ash, which has gradually become an important choice for sludge disposal. The European Union and the vast majority of countries are also in favor of sludge land reuse.

Although the land resources in North America are abundant, the sludge is seldom used for sanitary landfill. In these areas, the treatment and disposal of sludge is mainly based on agriculture, and a lot of evaluation work has been done for sludge agriculture.

However, due to the limitation of land, the disposal route of sludge in Japan is mainly to make building materials after incineration, supplemented by agriculture and landfill. In recent years, we have begun to adjust the treatment and disposal route of sludge, pay attention to the utilization of sludge biomass, and reduce sludge incineration.

Sludge treatment and disposal in developed countries are relatively clear about the route of land use. Land use can not only be used as fertilizer for crops, pastures, woodlands and landscaping, but also as a substrate for improving sand wasteland and saline alkali land. However, due to transportation problems, operation difficulties and other reasons, the cost of sludge farming is far higher than soil improvement. Anaerobic digestion and aerobic digestion are widely used in Europe and America. Although sludge is stabilized and pasted for harmless treatment, it provides a good foundation for land use.

Status of sludge treatment and disposal in China

With the continuous improvement of urban sewage treatment rate, the output of sludge is also increasing rapidly. At present, the number of urban sewage treatment plants in China has exceeded 2000, and the annual sewage treatment capacity has more than doubled compared with the period of the tenth five-year plan. According to incomplete statistics, only a small part of sludge in sewage treatment plants nationwide has been landfilled, used for land, burned and built materials, while the rest have not been treated and disposed in a standardized way. These sludge have high moisture content, large volume, perishable, odor, and contain a large number of toxic and harmful substances such as heavy metals and bacteria. If they are directly discharged into the external environment without scientific treatment and disposal, they will cause great pollution to the surface water, soil, groundwater and air, and have adverse effects on human health.