Industrial wastewater discharge – sulfates – assistance, thank you very much
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Expert in waste treatment: May I ask whether wastewater containing high concentrations of sodium sulfate can be discharged directly into the sewage system? It contains basically no other pollutants; since no relevant standards have been found and I have no experience with this, I’m not sure whether it’s safe to discharge it directly. Thank you very much
It shouldn’t be possible. The sewage erosion degree and total salt content are definitely above the limits.
Wastewater containing high concentrations of sodium sulfate is frozen and crystallized to yield solid sodium sulfate, which is then reduced using coal dust to produce sodium sulfide. This substance can be sold as a water treatment agent; the price of industrial sodium sulfide is between 1,800 and 2,600 yuan per ton
Although I don’t know what sulfate is, its name suggests it has corrosive properties, so it can’t be discharged casually
It cannot be discharged directly! Concentrated evaporation crystallization is carried out using a multi-effect evaporation process to remove salts and organic substances (if any) from the water. The original solution is heated with steam, and the water vapor produced during evaporation is condensed and reused. What remains is a highly saline residue, which is then cooled to induce crystallization, allowing the salts and organic substances to precipitate out.
Can it only be concentrated to extract salts? Is there no other way? Doesn’t this seem to result in higher energy consumption?
It cannot be discharged directly; the salt content is subject to specified limits. Please check the discharge standards set by the local environmental protection authorities regarding the specific requirements for chloride ions and sulfate ions. If such standards are not available, refer to the **discharge standards**. The sulfate requirement for urban sewers in Shanghai is 500 ppm.
1. What scale of ice machine do you need for freezing and crystallization? 2. How to separate solids from liquids after freezing? One can’t assume things.