Removal Characteristics Of Organics By The Combined Process Of Miex And Coagulation-sedimentation

Magnetic Ion Exchange Resin (MIEX) is effective in removing organics fromwater and usually followed by coagulation-sedimentation. This study was performed toprovide technical support for the use of combined process of MIEX andcoagulation-sedimentation. The influence of inorganic anions and organiccharacteristics on the MIEX removal effect was examined. Comparative study of thefeasibility of coagulation-sedimentation+MIEX was also implemented. Furthermore,the study evaluated application effect of MIEX engineering in Huaian.By competing exchange sites with organics, SO42-and NO3-reduced organicsremoval efficiency, while the influence mechanism of Cl-was to curb the ion exchangereaction of MIEX. According to the research results, SO42-had greatest impact onorganics removal efficiency，while the impact of NO3-and Cl-was relatively small. Theremoval efficiency of UV254and DOC decreased13%and15%linearly when SO42-increased to163.5mg/L.MIEX could remove HPIA to some extent in source water, ranging from27%to46%, but the removal efficiency was below TPHA and HPOA. As molecular weightrose, the discipline of the removal ability of MIEX could be analyzed in two intervals.The removal efficiency increased with molecular weight rising when<5kDa. However,it tended to decrease with molecular weight rising when>5kDa. When molecular weightwas <5kDa, organic matter tended to have higher content of low aromaticity hydrophilicorganics as molecular weight became lower. MIEX had relatively weak ability toremove low aromaticity hydrophilic organics, and then removal efficiency increased asmolecular weight rose. When molecular weight was>5kDa, molecules of organics grewto limit the use of internal exchange resin sites, therefore, removal efficiency tended todecrease as molecular weight rose.The coagulation-sedimentation+MIEX process had good feasibility. Theprocesses of MIEX+coagulation-sedimentation and coagulation-sedimentation+MIEX both removed turbidity well, while the organics removal efficiency of the latterprocess performed relatively more stable. For the two combined processes, the removalrates of DOC were over53%and that of UV254were over66%.In the effluent watertreated by the two processes, concentration of ultraviolet absorption organics was very low. At the same time, coagulation-sedimentation+MIEX process removed more lowmolecular weight organics and HPIA than MIEX+coagulation-sedimentation. As aresult, the content of small molecular, hydrophilic organics in effluent water treated bycoagulation-sedimentation+MIEX was less than MIEX+coagulation-sedimentation.In a practical application, MIEX engineering could effectively remove organicsand the removal effect showed UV254＞DOC＞CODMn. During the same period, theremoval effect of THMFP and HAAFP achieved by the process of MIEX+coagulation-sedimentation was well above the conventional coagulation-sedimentation.The removal efficiency of SO42-was16.5%in actual engineering. NO3-couldn’t beremoved. The concentration of Cl-in water increased after MIEX treatment. Therunning cost of MIEX was about0.199YUAN/m3.