Sludge is mainly composed of low-level organic compounds such as amino acids, humic acid, bacteria and their metabolites, polycyclic aromatic hydrocarbons, heterocyclic compounds, organic sulfides, volatile odors, organic fluorides, etc. In addition, it also contains inorganic substances and heavy metal substances such as mercury, cadmium, and lead. Sludge is a by-product with a large volume generated from sewage treatment, generally with a moisture content of 80-90%. For every 10000 cubic meters of sewage treatment capacity, more than 10 tons of sludge can be produced (calculated based on sludge with a moisture content of 80-90%).