Effect mechanism of sulfate on fluoride ion removal from waste battery wastewater
Fluorine containing wastewater exists widely,and calcium salt precipitation is one of the commonly used methods in treating high fluoride wastewater.However,in the treatment of actual wastewater,it is always hard to achiere the ideal effect and,requires secondary coagulation treatment.Therefore,this study took an actual battery high fluoride wastewater as an example to study the effect of calcium salt precipitation operating parameters on the fluoride removal ef-fect.It was found that under the conditions of calcium salt dosage of 4 500～5 000 mg·L-1 and pH of 11.5,the fluoride re-moval effect was the best,but it could not meet the theoretical requirement of 8 mg·L-1.Subsequently,through water dis-tribution experiments,the interference of coexisting ions in wastewater on calcium salt fluoride removal was investigated,and it was found that in the presence of sulfate,it could not be reduced to be below 10 mg·L-1.Analysis by energy disper-sive X-ray spectroscopy(EDS),Fourier transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD)shows that sulfate inhibits the removal of fluoride ions by competing with fluoride ions for calcium ions.Finally,The waste water can meet the requirements of sewage discharge after aluminum salt coagulation treatment or adding phosphate to produce cal-cium fluorophosphate precipitation.
fluorine removalsulfateco-precipitationcalcium salt precipitation
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