How to remove sulfate and F ions from wastewater in an economical and efficient manner
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Dear colleagues: The enterprise’s production process generates wastewater containing sulfate ions (2–20 g/l, with unstable levels) and F ions (5–8 g/l), at a pH of around 7–8.5, in a volume of 30 tons per day. Currently, this company uses the calcium chloride method, which is primarily used to remove F ions; however, sometimes the concentration of sulfate exceeds 10 g/l, requiring more calcium chloride and thus increasing costs. Now, companies want to replace calcium chloride with slaked lime (calcium hydroxide), but since calcium hydroxide has low solubility, will its actual performance be unsatisfactory? If any of you colleagues have practical experience, I would be grateful if you could share your insights.
Adding calcium hydroxide will be effective, but it will raise the pH and also react with other heavy metals.