纳滤
氟化物
碱度
反渗透
化学
过滤(数学)
膜
地下水
膜技术
水处理
环境化学
水质
环境工程
铝
色谱法
制浆造纸工业
无机化学
环境科学
地质学
有机化学
工程类
生态学
生物化学
统计
数学
岩土工程
生物
作者
Riitta Kettunen,Pertti Keskitalo
出处
期刊:Desalination
[Elsevier]
日期:2000-12-01
卷期号:131 (1-3): 271-283
被引量:55
标识
DOI:10.1016/s0011-9164(00)90025-0
摘要
Certain areas in Finland have a problem of high fluoride and aluminium in groundwater because of soil properties. In 1999, the City of Laitila constructed a membrane filtration plant (16–25m3/h) to control fluoride and aluminium concentration in drinking water. The plant has two trains, one with reverse osmosis (RO) and the other with nanofiltration (NF). Only a fraction (ca. 1/4) of water distributed is membrane filtered. The rest flows directly to alkalization. The alkalization process includes two limestone filters: one for membrane-filtered water (RO+NF) and the other for untreated groundwater. During the first year of operation, both RO and NF were shown applicable for fluoride removal from soft, high fluoride (ca. 4 mgF/l) ground water. The fluoride removals were on average > 95% in RO at 7.3 bar and 76% in NF at 5.7 bar. More than 78% of aluminium was also removed in membrane filtration. Temperature (2–16°C) affected permeated conductivities in the NF unit but not in the RO unit. Limestone filtration was shown applicable for alkalization of membrane filtered water. The alkalinity of membrane-filtered water rose back to the level it was before membrane filtration. However, alkalinity achieved with membrane-filtered water was lower than with groundwater while pH obtained was higher. This mainly resulted from the difference in carbon dioxide concentration of these waters. Since start-up of the RO/NF plant, fluoride and aluminium concentrations in the water distribution system have been at acceptable levels (≤1.5 mgF/l, ≤0.2 mgAl/l) while limestone filtration has ensured a stable alkalinity and pH. The cost of membrane filtration was ca. Euro 0.2/m3 permeate.
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