In general wastewater treatment, how should the dosage of ferrous sulfate and the pH be controlled?
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It was my first time conducting a pilot test for coagulant addition, and I wasn’t sure about the specific procedures. I used ferrous sulfate as the coagulant; after trying for a long time, I was unable to determine the correct dosage. If too little was used, the water turned yellow, and no reaction occurred； Too much was added; there are green floccules. The water became clearer, but it also took on a yellow color. I tried first dissolving ferrous sulfate in water and then adding it to the wastewater, but as soon as ferrous sulfate was added to the water and stirred, the solution turned yellow. So the dry pouring method was tried instead, but it didn’t work either; the water remained yellow. What should I do? I’ve been trying for two days now; I feel so dizzy. Please save me!
Firstly, dry application of ferrous sulfate is inappropriate, as water and the chemical do not come into sufficient contact, which affects the efficiency of the reaction.
Let’s use ferric sulfate polymer as the coagulant.
You must add hydroxide in order to form an electron bridge.
Lime, or calcium hydroxide, used in combination with ferrous sulfate yields good results. Generally, lime is added to the wastewater to raise the pH to around 10–11, ferrous sulfate is added to lower the pH to 7–8, and non-ionic PAM is used for coagulation. The laboratory sample is used to fine-tune the dosage of chemicals and determine the optimal pH level. This method is very effective for leather, papermaking, and dyeing wastewater; the only drawback is the large amount of sludge generated.