【作者】 李诚；

【导师】 黄廷林； 何文杰；

【作者基本信息】 西安建筑科技大学 ， 环境工程， 2013， 博士

【摘要】 近年来随着水环境的逐渐恶化，饮用水标准的逐渐提高，净水厂常规处理工艺的局限性越发凸显，传统处理工艺的升级改造势在必行。目前，超滤膜技术作为第三代城市净水技术的核心技术，受到越来越广泛的关注。本研究结合天津市杨柳青水厂处理工艺的升级改造，以浸没式超滤膜为基础，利用中试系统，对超滤膜集成工艺进行了深入研究，主要研究成果和结论如下:（1）膜出水浊度与混凝剂的种类和投加量无关。采用不同混凝剂预处理后的膜出水浊度均在0.075NTU左右，不同强化混凝技术对膜出水有机物的去除效能及对膜污染的控制效能有一定的相似性，均为PACl最优，FeCl₃其次，AS最差。PACl对不同特性有机物的预处理效能优于FeCl₃和AS，尤其在去除亲水性和小分子量有机物方面更具有优势。采用正交试验与加权评分法相结合的方法，综合考虑膜系统出水水质、△TMP及产水率三方面因素，得出膜系统最佳运行参数为：膜通量18L/m²·h，过滤周期90min，5周期排空一次，反洗流量3.6m³/h，反洗时间60s，气冲流量3.2m³/h。（2）采用投影寻踪聚类分析法对杨柳青水厂水源水进行了水质分期，将源水划为了三个水质期：低温期（12月～次年3月）；高藻期（6月～9月）；正常期（4月～5月，10月～11月）。不同水质期源水中溶解性有机物以强疏水性有机物和亲水性有机物为主，其中又以分子量＜500Da的有机物所占比例最高。考察膜集成系统对不同水质期水中污染物的去除效能得出，各水质期膜出水浊度均能保持在0.1NTU以下，颗粒物均小于10个/mL，对原水CODMn的去除率在45%左右，对UV254和DOC的去除率均在25%左右，对水中的细菌和藻类物质几乎可以全部去除；研究还发现系统对原水疏水性有机物和大分子量有机物具有较好的去除效能，而对亲水性有机物和小分子量有机物去除效能较差。（3）低温期水中溶气析出是影响膜系统稳定运行的主要因素，采用控制初始和上限TMP的运行方式虽然可在短期实现膜系统的稳定运行，但是会增加系统运行的成本和难度，影响运行的连续性，而采用气水分离和自控组合技术，可有效实现水中气泡的收集和排出，避免其对膜系统稳定运行的影响。高藻期经预氯化后会使混凝出水中疏水性有机物和小分子量有机物含量增多，不仅降低了系统对有机物的去除效率而且加剧了膜污染；采用生物操控预处理技术，可以有效降低原水中藻类的含量，出水藻类计数平均为2773万个/L，比未采用生物操控技术时降低了约42.9%，并可在确保膜出水水质的前提下，降低藻类对膜系统的影响，实现膜系统的稳定运行。（4）以受污染超滤膜为研究对象，考察了不同水质期EFM的清洗方式为：正常期和低温期以柠檬酸清洗为主，间歇采用次氯酸钠清洗，高藻期则采用相反的清洗方式。对低温期和高藻期受污染膜表面进行SEM和能谱仪分析，得出不同水质期造成膜污染的物质元素基本一致，区别在于低温期膜污染主要为无机物污染，而高藻期为有机物污染；采用原子吸收分光光度法和GC/MS分析法对化学清洗洗脱液进行成分分析后，认为膜表面的无机物污染主要是由Fe盐在膜表面的沉积造成的，而有机污染物主要为小分子量不饱和疏水性芳香族化合物。（5）采用实际工程与中试相结合的方式，对比常规工艺、压力式膜工艺、浸没式膜工艺的除污效能和经济性，对污染物的去除效能压力式膜工艺略优于浸没式膜工艺，但相差不大，均优于常规工艺，其中对浊度和耗氧量的去除率约比常规工艺提高了4%和6%，膜出水余铁均＜0.05mg/L；一次性产水率均高于85%；运行成本常规工艺较低，分别比压入式膜工艺和浸没式膜工艺节省了32.2%和21.6%.采用构建层次分析模型的方法，从不同工艺的“成本”和“效益”两方面着手，对不同工艺进行综合评价，得到常规工艺、压入式膜工艺和浸没式膜工艺的重要性权重为（0.2518,0.3318,0.4164），按权重越大越优原则，得出浸没式膜工艺相对于其他两种工艺更适合于杨柳青水厂的生产运行。更多还原

【Abstract】 In recent years, with the deterioration of water environment and the standard ofdrinking water improved, the limitations of conventional technology become apparent,Upgrading and improving the traditional is imperative. Ultrafiltration membranetechnology as a key technology of the third generation water purification technologyhas been widely concerned. This research, based on submerged membrane ultrafiltration,combing with the upgrading treatment technology of Tianjin Yangliuqing Water Plant,using the pilot system, has made a deeply study on ultrafiltration membrane integratedtechnique. The main results and conclusions are as follows:（1） The membrane effluent turbidity is irrelevant to the type and dosage ofcoagulants. After pretreatment with different coagulants, the membrane effluentturbidity is about0.075NTU, and there have been the certain similarity for the effluentorganics removal efficiency and the effect on membrane pollution control, that is, PAClis optimal, the FeCl₃is second, and AS is worst. The pretreatment efficiency of PAClfor different characteristic organics is better than FeCl3and AS, especially in the way ofeliminating the hydrophilic and small molecular weight organics. With the applicationof both orthogonal test and weighing scoring method, consideration of the three factorsof effluent quality,△TMP and water production rate, the optimal operating parametersof membrane system obtained: Membrane flux18L/m²·h, the filter cycle90min,5cycleperiod for one emptying time, backwash flow rate3.6m³/h, backwash time60s, gasflushing flows3.2m³/h.（2） With the application of projection pursuit clustering analysis method, thesource water has been classified into three water quality periods: low temperatureperiod （from December to March of the next year）, high algae period （from June to September） and normal period （from April to May and from October to November）.Dissolved organics are mainly composed by strong hydrophobic and hydrophilicorganics in different water quality periods, and among which, the organics of molecularweight <500Da occupies the highest proportion. Through investigation of the pollutantsremoval efficiency of membrane integrated system in different water quality periods,the results show the turbidity of the membrane effluent can be maintained less than0.1NTU, particulate matter is less than10/mL, the removal rate of CODMnis about45%,and the removal rate of UV254and DOC are around25%, and all of the bacteria and thealgae in the water can be almost removed entirely; the membrane integrated systemperforms better in the removal of hydrophobic and large molecular weight organicscontained in raw water, but poorly of hydrophilic and small molecular weight organics.（3） In low temperature period, the precipitation of dissolved gas from water is themain factor affecting the stability of the membrane system. Controlling initial and upperlimit TMP can make membrane system stable operation in short period, which mayincrease the cost and difficulty of system operation, however. The integrated applicationof gas-water separation and self-control technologies can effectively collect anddischarge water bubbles, and ensures the stable operation of the membrane system. Thepre-chlorination in high algae period will cause the hydrophobic organics and lowmolecular weight organic content to increase in coagulation effluent, which will notonly reduce the system organic removal efficiency but also exacerbate the membranepollution; However, the biomanipulation pretreatment process can effectively reducethe algae content in raw water. The average content of algae in effluent counts2773million/L, decreased by42.9%. It can reduce the impact of algae on the membranesystem and guarantee the stable operation of the membrane system, without side effectson membrane effluent quality.（4） Aiming at contaminated ultrafiltration membrane, after investigation of theEFM cleaning mode in different water quality periods,the study shows: in normal andlow temperature periods, citric acid is mainly used, with intermittent use of sodiumhypochlorite, and in high algae period, the cleaning way is opposite. Through SEM andEDS analysis of contaminated membrane surface in special water quality periods, theconclusion has been drawn that the membrane fouling in different water quality periodsis caused by basically the same material elements. The only difference between them isthat the membrane fouling in low temperature period is mainly caused by inorganicmatters, while the membrane fouling in high algae period is caused by organic matters.After component analysis of eluent by means of atomic absorption spectrophotometry and GC/MS analysis methods, the results show that the inorganic pollution tomembrane surface is mainly caused by the deposited ferric salt on the membranesurface, and that the organic pollutants are mainly consist of small molecular weightunsaturated hydrophobic aromatic compounds.（5） With the integrated application of both actual project and pilot test, bycomparing with the pollutant removal efficiency and economy between the conventionalprocess, the pressured membrane process, and the submerged membrane process, theresearch shows that in terms of the pollutant removal efficiency, the pressuredmembrane process performs slightly better than the submerged membrane process, butwithout significant difference. The both are superior to the conventional process. Theremoval rates of turbidity and CODMnof the two membrane processes respectively riseby about4%and6%than the conventional process, and the residual ferric in membraneeffluent is <0.05mg/L. The disposable water production rates of different processes areall above85%. In terms of operating cost, the conventional process is economical,saving by32.2%and21.6%compared with the pressured membrane process and thesubmerged membrane process. Combining with other influence factors, a analytichierarchy model has been established. Considering of “cost” and “benefit”, the eventualconclusion obtained that the weight value of the conventional technology, pressuredmembrane technology and submerged membrane technology is separately（0.2518,0.3318,0.4164）. By the principle of “the more weight value, the moreadvantages”, it’s believed that the submerged membrane technology is more suitable forYangLiuQing Water Plant production and operation than the two others.更多还原