化学沉淀法处理除氟吸附剂再生尾液的试验研究

Treatment of Wastewater Produced during Fluoride Adsorbent Regeneration Using Chemical Precipitation

通过试验研究了投加石灰法、投加氯化钙法、石灰-氯化钙联合法、石灰-盐酸联合法4种化学沉淀法对除氟吸附剂再生尾液的处理效果和影响因素。结果表明:静置沉淀90min后,使用投加石灰法处理pH值为12、含氟浓度为2 000mg/L的除氟吸附剂再生尾液,处理后残余氟离子浓度大于50mg/L,使用投加氯化钙法,处理后残余氟离子浓度小于20mg/L,使用石灰-氯化钙联合法和石灰-盐酸联合法,处理后残余氟离子浓度均小于10mg/L;4种方法的最佳搅拌强度为150r/min,最佳反应pH值为12左右,最佳静置时间为90min;其中,采用石灰-盐酸联合法处理pH值为12、含氟浓度为2 000mg/L的高氟再生尾液,在石灰投加量超过理论量60%(即为6.231 6g/L),加入65.4mL/L 2M的HCl时,出水可以达到国家污水排放一级标准,且pH值在7左右。

Fluoride removal was studied from wastewater produced during fluoride adsorbent regeneration using lime addition, calcium chloride addition, the addition of lime and calcium chloride and the addition of lime and hydrochloric acid. Factors affecting F- removal efficiency were investigated. Results showed that residual F- was over 50 mg/L after 90-minute reaction using lime addition to treat F- wastewater with the F- of 2 000 mg/L and the pH of 12,over 20 mg/L using calcium chloride addition,and less than 10 mg/L by the addition of lime and calcium chloride or the addition of lime and hydrochloric acid. For all these methods,the optimum shaking rate was 150 rpm,the optimal pH about 12,and the optimal precipitation time 90 minutes. Regarding the wastewater with the pH of 12 and the F- of 2 000 mg/L, the addition of lime and hydrochloric acid led to the residual F- concentration less than 10 mg/L and the pH around 7.0, with the lime dosage of 6. 231 6 g/L and 2 M HCl addition of 65.4 mL/L,which meet the national effluent standards.