摘要：

近年来含氟工业废水的大量排放严重危害生态环境及人类健康，受到人们的高度关注。含氟工业废水日益严格的排放标准推动了废水除氟技术的迅速发展。混凝法是废水除氟的有效方法之一，但目前混凝剂理化指标、工艺参数与混凝除氟效果之间的相关性还缺乏深入研究。考察了聚合氯化铝（PACl）主要理化指标（氧化铝质量分数、盐基度）、投加量、pH、铝形态等对混凝除氟效能的影响，并采用实际含氟工业废水进行了验证。结果表明，PACl中氧化铝质量分数和盐基度对混凝除氟效果均有一定程度的影响，其中盐基度对除氟效能的影响程度更大；PACl投加量100~900 mg/L时，盐基度与F^-去除率呈正相关性，PACl投加量100~500 mg/L和600~900 mg/L时，氧化铝质量分数与F^-去除率分别呈正相关性和负相关性；高氧化铝质量分数（28%~35%）和高盐基度（75%~89%）的PACl投加600~700 mg/L处理10 mg/L的含氟废水时，出水F^-质量浓度在1.28~1.40 mg/L，可达到深度除氟的水平。PACl投加量显著影响混凝除氟的效能，在PACl投加量100~300 mg/L范围，F^-去除率与混凝剂投加量正相关。PACl混凝除氟的适宜pH范围在6~8，此范围内F^-去除率与低聚合态铝（Al_a）占比呈显著负相关，与中聚合态铝（Al_b）占比呈显著正相关，其中pH=7时除氟效果最佳，此时7种PACl形成的Al_b平均占比均达到最高（51.55%）。PACl混凝处理实际含氟工业废水过程中，混凝剂主要理化指标、混凝参数等对除氟效果的影响与模拟含氟废水结果相近，且呈现出相同的变化趋势。

关键词: 含氟工业废水, 混凝, 深度除氟, 相关性

Abstract:

In recent years, the substantial discharge of fluorine-containing industrial wastewater has posed a severe threat to the ecological environment and human health, thereby garnering significant attention. The ever-tightening discharge standards for fluorine-containing industrial wastewater have spurred the rapid development of fluoride removal technologies. Coagulation is recognized as one of the effective approaches for wastewater defluorination. However, in-depth research on the correlations among the physicochemical properties of coagulants, process parameters, and the fluoride removal efficiency of coagulation remains insufficient. This study investigated the impacts of the main physicochemical properties of polyaluminum chloride (PACl) (the mass fraction of Al₂O₃ and basicity), dosage, pH and aluminum speciation on coagulation fluoride removal efficiency, The results were verified using actual industrial fluoride-containing wastewater. The results indicated that both the mass fraction of Al₂O₃ and basicity of PACl had certain influences on the fluoride removal efficiency of coagulation, among which the basicity had a greater impact on the fluoride removal efficiency. When the dosage of PACl was 100-900 mg/L, the basicity exhibited a positive correlation with the F^- removal rate. When the dosage of PACl were 100-500 mg/L and 600-900 mg/L, the mass fraction of Al₂O₃ was positively and negatively correlated with the F^- removal rate, respectively. When the dosage of PACl with a high mass fraction of Al₂O₃ (28%-35%) and high basicity (75%-89%) for treating 10 mg/L fluoride-containing water was 600-700 mg/L, the F^- mass concentration in the effluent was 1.28 to 1.40 mg/L, achieving the level of advanced fluoride removal. The dosage of PACl significantly influenced the fluoride removal efficiency of coagulation. Within the dosage of 100-300 mg/L of PACl, the F^- removal rate was positively correlated with the coagulant dosage. The appropriate pH range of PACl coagulation for fluoride removal was 6-8. Within this pH range, the F^- removal rate was significantly negatively correlated with the proportion of low-polymeric aluminum (Al_a) and significantly positively correlated with the proportion of medium-polymeric aluminum (Al_b). The optimal defluorination performance was achieved at pH 7, at which the average proportion of Al_b formed by seven types of PACl reached its peak value of 51.55%. During the treatment of actual fluoride-containing industrial wastewater using PACl coagulation, the impacts of the main physicochemical indexes of coagulants and coagulation parameters on fluoride removal efficiency were comparable to those observed in simulated fluoride-containing wastewater experiments, and showed consistent changing trends.

Key words: fluoride-containing industrial wastewater, coagulation, advanced fluoride removal, correlation

中图分类号: 

• X703