[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.
Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China. mpeggy@163.com
Wei-Fang
WF
Ma
Wen-Jun
WJ
Liu
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