Sulphide Precipitation Integrated Membrane For Heavy Metal Pollution Of Groundwater

Heavy metal is a common type of pollutant during accidental pollutions. In recent years, the frequency and intensity of accidental heavy metal pollution events tends to increase in China. Once the occurrence of heavy metals pollution of groundwater, human beings and the environment will pose a serious threat. In this paper, sulfide precipitation - membrane treatment of heavy metal pollution in water to sodium sulfide as a heavy metal precipitating agent, of pH, sodium sulfide dosage, heavy metal co-exist, the solution of inorganic ions and other factors on the impact of removing heavy metal ions, and compared with the hydroxide precipitation method.Polymer flocculant effect on the settlement of metal sulfides and on the S2- in solution was discussed. This article also compared the treatment efficiency and performance between ceramic membrane and Polyvinylidene fluoride. Through small pilot tests, the water has basically reached the groundwater quality standard ClassⅢwater, and the technology achieved rapid and effective removal of heavy metals in polluted groundwater.The results will provide a theoretical basis and technical demonstrations for Sulphide Precipitation integrated Membrane reactor for heavy metal pollution of groundwater.The main conclusions were listed as follows: The sulfide precipitation has three points advantage compared with the hydroxide precipitation. the equilibrium concentration and pH in the solution by the sulfide precipitation was significantly lower than which by the shydroxide precipitation, and the impact of inorganic ions on hydroxide precipitation is greater.In sulfide precipitation for single heavy metal, pH had a great impaact on the removal of Zn, Pb and Cd. The best molar ratio of removal of Pb2+,Cd2+,Ni2 +is 1.4,1.8,1.8, and the concentration is less than 0.05mg /L. Under the same dosage of Na2S, the concentration of heavy metals in mixed heavy metal solution decreased. Inorganic ion is weakened sulfide removal of heavy metal ions, the largest decline is about 12%, which has some negative impact. PAC and PFS make the precipitation destabilization of colloidal particles, PAC is better than the PFS. When the PAC dosage of 40mg/L, PFS dosage of 55mg/L, the effluent heavy metal concentration is less than 1.0mg/L. Meanwhile, PAC and PFS can effectively remove the S2-, with the increased using of flocculants, S2- removal rate is increase. Under the same dosage, PFS is better than the PAC.During the time the sulfide precipitation - membrane reactor run 6 cycles, the water quality is stable. After membrane filtration unit , the water quality achieve up to standard. Ceramic membrane is better than PVDF, the more acid and alkali, and a longer service life compared to PVDF. ORP can effectively give a response to the removal of heavy metal. When the ORP≥110mv, the heavy metal removal effeceltely. Meanwhile, the sulfide precipitation - membrane reactor has good impact resistance.