About ferrous sulfate
Thread Content
I used to add PAC, but my supervisor suggested trying ferrous sulfate instead; now there are many problems... (I’m seeking advice from experts.) The concentration of the prepared ferrous sulfate is quite high – will a regular pump work for pumping it? Ferrous sulfate is corrosive; does that mean only acid-resistant pumps can be used to pump it? % k+ M! T2 N9 A8 q 2. A current phenomenon: at a pH of 10–11, ferrous sulfate yields the best results. However, when the pH of the printing and dyeing wastewater is below 10, adding ferrous sulfate causes the color to turn very dark. Is this the same phenomenon for all types of wastewater? 7 Z& N+ ~: B8 B& g" @$ J. When it’s in operation, adding ferrous sulfate right away can help remove some of the color and suspended particles. Strangely enough, the color becomes very dark at the back of the sedimentation tank; adding more of this substance doesn’t change that effect (logically, more should make the color redder, right?). Is this phenomenon only observed with textile dyeing wastewater? Is it some substance in the water that reacts with ferrous sulfate to produce this effect? Adding ferrous sulfate introduces too many sulfate ions into the system; if these sulfate ions are not removed, won’t they affect the biological system? What should be done then?
Ferrous sulfate is indeed corrosive; it is best to use an acid-resistant pump for its addition. The darkening that occurs when ferrous sulfate is added is likely due to a reaction between the ferrous ions and certain ions present in textile dyeing wastewater, such as sulfur ions; this results in the formation of ferrous sulfide, which is black in color. The usage conditions of ferrous sulfate are related to the pollutants in water quality; it can generally be used at a pH of 6–9. The flocs and flocculates formed by ferrous sulfate are larger in size, which is why it is used more frequently. Compared with PAC, its range of applications is narrower; in most cases, PAC is more effective for treating wastewater.