《Desalination》杂志刊登“芬兰三年来对低能耗除氟反渗透膜进行大规模现场试验”

 
作 者：Peter Sehn
刊 物：《Desalination》，2008年，223卷第1-3期，73-84页
关键词：除氟；反渗透；膜；低能耗；现场试验
摘 要：1）北欧地区饮用水水源为湖水，为使得饮用水质量可靠、安全，当地形成一种典型的、自然的处理方式，即湖水通过入渗进入地下含水层并停留50天，在这个过程中可去除色度、铁、锰，使得饮用水得到净化。然而，由于芬兰南部地区特殊的地质构造，当饮用水在入渗过程中经过土层时，土壤中的氟溶解至饮用水中，致使饮用水中氟化物含量由0.7 mg/L升高至1.8 mg/L，超过欧盟对饮用水中氟化物含量的限值1.5 mg/L。2）为保障居民饮水安全，自2003年9月起， 由KLV公司建设一处日处理水量为6000m³的反渗透水厂。由反渗透处理后的饮用水，其氟化物含量小于0.03 mg/L，供水时，采用反渗透处理后水与原天然水进行混掺，保障所供饮用水中氟化物含量小于1.3 mg/L，从而向多地区进行供水。3）反渗透处理水厂仅处理供水量的30%即可达到处理目标。FILMTEC™ XLE反渗透膜仅在压力为0.6-1.1MPa、温度为5-11℃即可运行，节能并降低运行成本。4）不添加任何阻垢剂的情况下，反渗透膜可达到80%的回收率。浓缩液中氟化钙含量过度饱和。反渗透膜在运行过程中，需定期清洗预防沉淀物残留在反渗透膜中。反渗透膜根据运行情况，自动启动清洗过程，预防反渗透膜的污染。一般情况下，第一次启动清洗过程是运行半年后。如不清洗，运行至一年半时，反渗透膜会产生大量有机物污染。采用pH值大于12的碱液清洗，清洗过程中保持温度35℃。经过3年多的运行，反渗透膜除氟降盐能力没有衰减。

Fluoride removal with extra low energy reverse osmosis membranes: three years of large scale field experience in Finland

Authors: Peter Sehn
Journal: Desalination, Volume 223, Number 1-3 (2008), 73-84
Key words: Fluoride removal; Reverse osmosis; Membrane; Low energy; Field experience
Abstract: Infiltration of surface water into the ground and a retention time of 50 days is a natural method to remove color, iron and manganese — which are typical for Nordic lake waters — and to produce a good quality drinking water. However, due to the geological situation in the Southern parts of Finland, the fluoride concentration increases after the soil passage from a typical value of 0.7 mg/L to values up to 1.8 mg/L. According to the drinking water directives of the European Union, the fluoride concentration shall be limited to 1.5 mg/L.In order to meet this standard, KLV, a public company which provides water to a number of municipalities, is operating a 6000 m3/d reverse osmosis plant since September 2003. The RO permeate water with a fluoride concentration of <0.03 mg/L is blended with the artificial ground water to ensure a fluoride level below 1.3 mg/L in the drinking water.By treating only 30% of the water, the treatment goal could be achieved with the lowest capital costs. FILMTEC™ XLE reverse osmosis membranes are used to minimize the energy consumption and thus the operating costs. The system operated at a pressure of 6–11 bar at a temperature of 5–11°C, which was until recently possible with nanofiltration membranes only.The RO system operated at 80% recovery without addition of any scaling inhibitor. The concentrate was four times oversaturated with calcium fluoride. Regular flushing was employed to prevent the deposition of precipitates. Sacrificial elements were operated on the concentrate to detect the onset of scaling early enough to initiate cleaning. A first preventive cleaning was carried out after half a year. Substantial fouling with natural organic matter occurred after one and a half year. This could be controlled with harsh alkaline cleanings at pH > 12 at a temperature of >35°C.After more than three years of operation, the salt and fluoride rejection of the membrane was as high as in the beginning.

原文链接：http://www.sciencedirect.com/science/article/pii/S0011916407008387
翻译：孙瑞刚；审核：陈康宁