[Influence of co-existing chloride on fluoride removal from drinking water by nanofiltration membrane].
The influence of co-existing chloride to defluoridation of groundwater using nanofiltration membrane and membrane fouling were studied. The results show that nanofiltration has retention effect to all co-existing anion. When influent fluoride concentration was less than 6 mg/L, the fluoride concentration in permeated water was less than 1.2 mg/L which could reach the drinking water standard in rural area. The fluoride retention rate decreases with the increase of influent fluoride concentration or co-existing chloride concentration. The decreasing percentage of fluoride retention rate is the same when Cl- concentration increased 1 mol or F- concentration increased 0.1 mol. The fluoride retention rate increased when influent chloride concentration exceeded 220 mg/L. But the variation had no significant change. Environmental scanning electron microscope (ESEM) and its energetic chart analysis apparatus, X-ray diffration (XRD) analysis showed that the main fouling component was CaCO3. The fouling membrane could be recovered flux using citric acid and ammonia cleaning method.
Ma
Wei-Fang
WF
Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China. mpeggy@163.com
Liu
Wen-Jun
WJ
D002712:Chlorides / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry / Q000302:isolation & purification*; D008567:Membranes, Artificial; D049329:Nanostructures / Q000737:chemistry*; D014462:Ultrafiltration / Q000379:methods; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000032:analysis*
D002712:Chlorides; D008567:Membranes, Artificial; D014874:Water Pollutants, Chemical; D005459:Fluorides