Drying Technology
Key words: physical sedimentation sludge,water supply sludge
There are many classification methods for sludge, which are briefly described as follows. (1) According to the source of sludge, it can be roughly divided into three types: water supply sludge, domestic sewage sludge and industrial wastewater sludge. (2) According to the process of sludge separation from water, it can be divided into sedimentation sludge (including physical sedimentation sludge, coagulation sludge, chemical sludge) and biological treatment sludge (referring to sewage produced in the secondary treatment process). sludge). Most of the sludge in modern sewage treatment plants is a mixture of sedimentation sludge and biological treatment sludge. (3) According to the composition and properties of sludge, it can be divided into organic sludge and inorganic sludge. Organic sludge with organic matter as the main component can be referred to as sludge for short. Organic sludge is hydrophilic sludge. Domestic sewage sludge or mixed sewage sludge is organic sludge. Inorganic sludge with inorganic matter as the main component is often called sediment. The sediment in the water treatment grit tank and some industrial wastewater physical and chemical treatment processes are all sediment. Inorganic sludge is generally hydrophobic sludge. (4) According to the classification and naming of the sludge in different treatment stages, there are raw sludge, thickened sludge, digested sludge, dehydrated and dried sludge, dried sludge and sludge incineration ash, etc. This method is the most commonly used method of sludge classification.
The main purpose of sludge treatment is as follows. (1) Reduce the water content to reduce the volume, which is convenient for the transportation and storage of sludge and various treatment and disposal processes. (2) Eliminate the organic matter, pathogenic bacteria and other toxic and harmful substances that emit foul smell, cause disease and pollute the environment, and make the sludge sanitized and stabilized. (3) Improve the composition and properties of sludge to facilitate the application, or to facilitate the recovery of energy and resources. With the promotion and development of wastewater treatment technology, the amount of sludge produced is increasing, and the types and properties are more complex. Toxic and harmful substances in wastewater are often concentrated in sludge, so sludge is one of the most serious factors affecting the environment, and attention must be paid to the treatment and disposal of sludge.
