General sludge dewatering agents are divided into organic and inorganic two categories.

1. Inorganic agents: inorganic sludge dewatering agents include polyferric aluminum chloride, polyferric sulfate, ferrous sulfate, polyaluminum chloride, basic aluminum chloride, ferric chloride, etc. Among them, iron salt is a more effective and cheaper inorganic reagent.

After adding the inorganic sludge dewatering agent, the sludge concentration can be greatly accelerated and the effect of filtration dewatering can be improved. However, the amount of it is larger, generally 5%-20% of the absolute dry weight of the sludge, so the cake volume increases. It is assumed that when ferric chloride is used as the agent, the sludge cake will corrode the equipment when it is burned.

2. organic agents: organic sludge dewatering agents including polyacrylamide and sludge conditioner. The organic sludge dewatering agent does not corrode equipment and does not contain chloride and calcium ions during use, which is conducive to the subsequent resource treatment of sludge. Polyacrylamide is commonly used in screw folding machines and belt filter presses. The sludge conditioner is generally used in the plate and frame filter press, which can make the sludge better break the wall, precipitation more sewage, make the sludge moisture content lower and the mud drier, do not cause the sludge increment, the sludge will not have a sticky state, and will not cause the sticky filter cloth.

The selection of high-efficiency sludge dewatering agents can choose better agents according to demand. At present, the sludge conditioner is the best dewatering agent used by the plate and frame filter press. The advantages are non-stick filter cloth, no corrosion equipment, no calcium ion chloride ions do not cause secondary pollution, low sludge moisture content, dry mud cake, sludge does not increase and so on.