化学还原法处理Cr（Ⅵ）废水沉淀及过滤效能

目的研究硫化亚铁（FeS）化学还原法处理Cr（Ⅵ）废水产生的沉淀物质与水分离的特性．方法采用硫化亚铁（FeS）与废水经化学还原反应后，沉淀、无机高分子絮凝剂絮凝沉淀、过滤方法．结果在单纯FeS还原反应-沉淀实验中，随着反应时间和沉淀时间的增加，对Cr（Ⅵ）的去除率也随之增加．化学还原-无机高分子絮凝剂絮凝-沉淀实验中，絮凝时间对Cr（Ⅵ）的去除效果起到重要作用，投加絮凝剂后对Cr（Ⅵ）的去除效果最好的是在絮凝时间为20min，沉淀时间为90min的时候，投加絮凝剂PAC对Cr（Ⅵ）的去除率为63．47％．过滤后，去除率可达99．77％和99．89％，Cr（Ⅵ）质量浓度降至0．16mg／L和0．08mg／L，达到排放标准．结论FeS的化学还原-沉淀-过滤法和化学还原-无机高分子絮凝剂絮凝-沉淀-过滤法均能有效去除Cr（Ⅵ）达到排放标准．

Analysis on Sedimentation and Filtration Efficiency of Hexavalent Chromium Wastewater by Ferrous Sulfide

The separation characteristic of the chromium settling separated from waste water by ferrous sulfide （FeS） chemical deoxidation method is studied. There is a deoxidation reaction between FeS and the hexavalent chromium wastewater, then sedimentation, inorganic polymer flocculation-sedimentation and filtration process are followed. In simple process of FeS deoxidation-precipitation reaction, the removal rate of hexavalent chromium increases with the increase of the reaction and precipitation time. And in deoxidation- inorganic polymer flocculation-sedimentation reaction, flocculation time plays an important part in the process of removing hexavalent chromium. When flocculating agent is added, the appropriate condition is that flocculation time is 20 min and sedimentation time is 90 min. The removal rate is 63.47% when PAC is used. After filtered further, the removal rates can reach 99.77% and 99.89%, and the concentrations of hexavalent chromium reduces to 0.16 mg/L and 0.08 mg/L which can meet emission-water quality. Hexavalent chromium in wastewater can be removed effectively through FeS deoxidation-sedimentation-filtration or deoxidation-inorganic polymer flocculation-sedimentation-filtration method and the treated water can comply with the emission standard.