地下水源膜法给水厂长期运行过程中膜性能演变

EVOLUTION IN MEMBRANE PERFORMANCE OF GROUNDWATER SOURCED WATERWORKS DURING LONG-TERM OPERATION

大庆油田水务公司西水源水厂以地下水作为主要水源,采用臭氧/活性炭+超滤膜(UF)处理工艺;自2014年投产至2019年底已经运行5年,水厂出水浊度、有机物(COD_(Mn))和菌落总数等水质指标均稳定达标,但超滤膜污染导致膜性能变化。为了探究5年运行过程中超滤膜处理性能演变情况,对膜出水水质、膜通量、跨膜压差和膜污染层等进行分析。结果表明:超滤膜对浊度和微生物的去除率保持在90%以上,对COD_(Mn)平均去除率维持在9%。运行5年过程中,超滤膜的比通量每年下降2.1%~4.6%,恢复性化学清洗(CIP)对超滤膜的通量与比通量恢复率分别维持在73%~91%和85%~92%。污染层分析结果表明,超滤膜的有机污染物主要是腐植酸和蛋白质等;无机污染物包括锰、铁、硅、钙和铝等。高价金属元素与有机物形成络合污染物,在污染层中起到支配作用;另外,钙和硅的无机盐垢也不可忽视。

Daqing Oilfield Xishuiyuan Water Plant took groundwater as the main water source,used conventional-ozone/activated carbon-ultrafiltration(UF)membrane treatment technology,and had been in operation for 5 years from its commissioning in 2014 to the end of 2019.The turbidity of the effluent from the water plant,organic matter(COD_(Mn))and total number of colonies reached the standard stably.However,ultrafiltration membrane fouling led to changes in membrane performance.In order to explore the evolution of ultrafiltration membrane water treatment and membrane performance during the five years operation,the water quality of membrane effluent,membrane flux,transmembrane pressure and membrane fouling layer were analyzed.The results showed that the removal rate of turbidity and microorganism maintained above 90%,while the average removal rate of organic matter was only 9%.The specific flux of the ultrafiltration membrane decreased by 2.1%~4.6%per year.Clean in place(CIP)in the flux and specific flux recovery rate of the ultrafiltration membrane were maintained in the range of 73%~91%and 85%~92%,respectively.The analysis results of the fouling layer showed that the organic pollutants of the ultrafiltration membrane were mainly humic acid and protein;the inorganic pollutants were manganese,calcium,iron,silicon and aluminium.Complex pollutants formed by high-valent metal elements and organic matter played a dominant role in the pollution layer;at the same time,inorganic salt scales with silicon and calcium shouldn’t be ignored.