Where should polyferric sulfate be added?

Everyone is familiar with polyferric sulfate. It is a polymer coagulant that has been widely used in the water treatment industry in recent years, and more and more people use it to replace polyaluminum chloride. It has the characteristics of simple operation, low cost, stable treatment effect, high treatment efficiency, etc., and can perform various functions such as coagulation, phosphorus removal, fluorine removal, COD removal, and decolorization in sewage treatment. So, when using polyferric sulfate, where should it be added? Some people say that it has been seen in the primary sedimentation tank, the biochemical outlet, the aeration tank and other places. So, where should it be added in order to improve the treatment effect? What are the differences between these different dosing positions?

1. Primary sedimentation tank

Adding polymeric ferric sulfate before the primary sedimentation tank is not uncommon in high turbidity wastewater. This type of wastewater contains a large amount of SS and insoluble substances (such as COD, colored groups, etc.). At this time, it mainly plays the role of removing non-soluble suspended matter, reducing the load of subsequent processing procedures, and improving the rate of compliance.

2. Aeration tank

When it is added to the aeration tank or the pipeline between the aeration tank and the secondary sedimentation tank, it is mainly used as a coagulant for coagulation, and the aeration tank is beneficial to accelerate the dissolution rate of polymeric ferric sulfate and The reaction speed between the phosphate, insoluble organic matter, suspended particles and colored groups in the secondary sedimentation tank makes the reaction more complete, can save coagulation time and improve the coagulation effect.

3. Biochemical water outlet

Polyferric sulfate can be added to the biochemical effluent before it can treat the residual phosphorus, COD and other substances in the biochemical effluent, so that the phosphorus and COD in the wastewater can meet the sewage discharge standards. In practical applications, the dosing position can be determined according to its use function.

1) When polyferric sulfate is used as a phosphorus removal agent, it can be added to the primary sedimentation tank if the phosphorus content is small. If the phosphorus concentration is high, it is added before the water in the secondary sedimentation tank.

2) When used as a COD remover, it can be added to the secondary sedimentation tank or biochemical outlet.

3) When coagulation is used to remove turbidity and SS, it is added to the coagulation tank or the front end of the sedimentation tank.