In the process of using ferrous sulfate, whether the dosage is large or small, it has a greater negative impact. Firstly, ferrous sulfate, as an acidic agent, will acidify the water when it is added in large amount, and a large amount of ferrous sulfate will produce a large amount of sludge when it is added in wastewater treatment. When the dosage of ferrous sulfate is small, the effect becomes very poor. Therefore, reasonable control of ferrous sulfate dosage is of great significance in practical use.

The small-scale test before the use of ferrous sulfate is necessary. Only when the suitable dosage of ferrous sulfate is obtained in the small-scale test, can it be controlled and adjusted according to the on-site dosing equipment. Ferrous sulfate can also be used in different ways because of different wastewater treatment processes.

For example: in urban sewage, due to the large amount of sewage treatment, ferrous sulfate is generally divided into two dissolving tanks for continuous dispensing, and ferrous sulfate solution is added to the sewage through the dosing pump. In industrial wastewater treatment, because there are many wastewater treatment industries, ferrous sulfate can be dissolved by aeration stirring, which can not only be fully dissolved, but also be fully mixed with wastewater. In some small processing equipment, the ferrous sulphate can be controlled by dissolving ferrous sulfate in the dissolution tank and adjusting the flow rate of the dosing pump. It is a mixture reaction of liquid and sewage at the sewer flow, which can achieve better results.

Therefore, the dosage of PFS should be reasonably used according to the different wastewater treatment and different treatment processes.