用于城市污水再生的浸没式超滤—反渗透工艺膜污染控制

发布时间：2018-08-15 14:41

【摘要】：本文以中国光大水务有限公司淄博再生水厂的浸没式超滤(UF)-反渗透(RO)双膜法工艺为研究对象,针对运行初期存在的问题,通过对工艺长达三年的跟踪检测与分析,分别考察了预处理、在线操作和化学清洗对超滤膜污染、反渗透膜污染的控制效果,及系统对污染物与盐度的去除效果,并对能耗、药耗等主要运行成本进行了评价。原水有机物、含盐量、铁、锰、硅、钙等含量较高,浸没式超滤作为反渗透的预处理单元,产水浊度99.49%的时间低于0.5NTU,SDI 97.8%以上的时间小于3,对CODCr的平均去除率为19.95%。在UF前适当投加混凝剂,可以延缓UF膜污染,降低UF产水CODCr,但铝盐会增加RO膜发生硅酸铝盐污染的风险。冬季使用蒸汽对原水加温,有利于缓解膜污染,增加的蒸汽成本为0.075元/m3水,实际应用较困难。投加Na Cl O并使UF产水余氯维持在0.3mg/L以上时,可以延缓UF膜污染。采用反冲洗周期15min、水洗强度为37.9 L/m2·h、曝气量为220m3/h的反冲洗方案,可有效控制膜污染。UF化学清洗效果显著,恢复性清洗后膜比通量可恢复至接近新膜水平。反渗透膜污染物主要是有机物,包括溶解性微生物代谢产物及腐殖酸类腐殖质。膜面污染物主要元素是C、O、Si、Al、Ca、Fe、S等。一段、二段膜面上均含有硅酸盐、羧酸类、氨基酸类等污染物,二段出水端还有硫酸盐存在。利用Na OH、螯合剂等组成的碱洗液可以有效去除RO膜上的有机污染物,碱洗后再用柠檬酸清洗有利于提高清洗后RO系统的脱盐率。增加维护性Na OH清洗,能有效延缓膜污染速率,提高膜通量。在连续运行三年后,UF整体通量稳定。RO膜元件性能检测结果显示一段第一支膜、二段最后一支膜产水量分别下降6.5%和19.3%;一段第一支膜脱盐率下降了0.5%,二段最后一支膜脱盐率没有下降,整体性能良好。电费、膜折旧费用在运行费用中占比最高。通过节能和控制膜污染措施,吨水电费呈逐年下降趋势。
[Abstract]:In this paper, the submerged ultrafiltration (UF) reverse osmosis (RO) double membrane process of Zibo Regeneration Water Plant of China Everbright Water Co., Ltd is taken as the research object. Aiming at the problems existing in the initial stage of operation, the process has been tested and analyzed for up to three years. The control effects of pretreatment, on-line operation and chemical cleaning on ultrafiltration membrane fouling and reverse osmosis membrane fouling, as well as the removal efficiency of pollutants and salinity by the system were investigated, and the main operating costs such as energy consumption and drug consumption were evaluated. Organic matter, salt content, iron, manganese, silicon and calcium contents in raw water are higher. Immersion ultrafiltration is used as pretreatment unit of reverse osmosis. The time of turbidity 99.49% is lower than that of 0.5 NTU SDI 97.8%, and the average removal rate of CODCr is 19.95%. Proper addition of coagulant before UF can delay the fouling of UF membrane and reduce the CODCr. but aluminum salt will increase the risk of contamination of RO membrane with aluminum silicate. Using steam to warm raw water in winter is helpful to alleviate membrane fouling and increase steam cost is 0.075 yuan / m3 water. It is difficult to apply in practice. UF membrane fouling could be delayed by adding Na Cl O and keeping residual chlorine above 0.3mg/L. When the backwashing cycle is 15 minutes, the washing intensity is 37.9 L/m2 / h and the aeration rate is 220m3/h, the chemical cleaning effect of membrane fouling. UF can be effectively controlled. The membrane specific flux can be recovered to the new membrane level after restorative cleaning. Reverse osmosis membrane pollutants are mainly organic compounds, including soluble microbial metabolites and humic acid humus. The main elements of membrane surface contaminants are C _ 2O _ O _ 2, Al _ 2O _ 3, C _ 2O _ 3, Fe _ 2O _ S, and so on. In the first stage and the second stage, silicate, carboxylic acid, amino acid and other pollutants were found on the surface of the membrane, and sulphate was found in the end of the second stage. The organic pollutants on RO membrane can be removed effectively by using NaOH, chelating agent, etc. After alkali washing and then cleaning with citric acid, the desalinization rate of RO system can be improved. The increase of maintenance NaOH cleaning can effectively delay the membrane fouling rate and increase the membrane flux. After three years of continuous operation, the overall flux of UF is stable. RO membrane element performance test results show that the first membrane, The water production of the last membrane of the second stage decreased by 6.5% and 19.3.The desalinization rate of the first membrane decreased 0.5%, and the last membrane of the second stage did not, and the overall performance was good. Electricity, membrane depreciation costs in the operating costs of the highest proportion. Through the measures of saving energy and controlling membrane fouling, tons of water and electricity are decreasing year by year.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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