硫酸根对废旧电池废水中氟离子去除的影响研究

Effect mechanism of sulfate on fluoride ion removal from waste battery wastewater

含氟废水广泛存在,其中钙盐沉淀是处理高氟废水常用方法之一。但是在处理实际废水时,往往达不到理想效果,需要混凝二级处理。为此,本研究以某实际电池高氟废水为例,研究钙盐沉淀运行参数对除氟效果影响,发现在钙盐投加量4500~5000 mg·L^(-1)、pH为11.5条件下,除氟效果最佳,但无法达到理论要求的8 mg·L^(-1)。随后通过配水实验探究了废水中的共存离子对钙盐除氟的干扰,发现在硫酸根存在的条件下,无法降到10 mg·L^(-1)以下。通过能量色散X射线光谱仪(EDS)傅里叶红外光谱(FTIR)和X射线衍射仪(XRD)分析表明,硫酸根通过与氟离子竞争钙离子,从而抑制了氟离子的去除。最后,废水再经过铝盐混凝处理或者投加磷酸盐生成氟磷酸钙沉淀后,满足污水排放要求。

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 4500~5000 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.