The sludge produced by sewage treatment can be divided into organic sludge and inorganic sludge. Organic sludge is mainly composed of organic substances and is the product of organic wastewater treatment. It is generally easy to corrode, fine particles, small specific gravity, high initial water content and difficult to dehydrate, and easy to be transported by pipeline. Inorganic sludge is mainly composed of inorganic substances and is the product of wastewater treatment by physical and chemical methods. It is generally not easy to corrode, has coarse particles, has a large proportion, has low initial water content and is easy to dehydrate, but has poor fluidity and is not easy to be transported by pipeline.