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题名: 纳滤膜在城市污水与工业废水回用中的应用及其膜 污染控制研究
作者: 李昆
学位类别: 博士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 魏源送 ; Municipal wastewater, industrial wastewater, advanced treatment and reuse, nanofiltration, membrane fouling
关键词: 城市污水,工业废水,深度处理与回用,纳滤,膜污染
其他题名: Applications of Nanofiltration in Municipal Wastewater and Industrial Wastewater Reclamation and its Membrane Fouling Control
学位专业: 环境工程
中文摘要:       近年来,纳滤膜技术在污水深度处理与回用中的研究与应用受到了越来越多的关注。本文以纳滤膜技术为核心,以城市污水和典型工业废水的回用为目标,着重从膜材料筛选、操作参数优化、膜污染机制及其清洗策略优化等入手,同时结合现场中试研究,分别开展了纳滤膜在城市污水深度处理、预处理-纳滤(MBRNF)组合工艺在纺织印染废水深度处理与回用中的研究,为今后城市污水处理厂的工艺升级改造和工业园区废水深度处理的工艺选取提供科技支撑。
    以城市污水二级生化出水为对象,混合均匀试验U15(54×31)和正交试验L9 (34)的结果表明,GE 公司的DK 膜在TMP=12 bar、pH=4、流量=8 L/min、T=30 oC条件下具有最优的出水水质。同对照结果(氧化沟—超滤组合工艺的出水仅能满足一级A 标准)相比,氧化沟—纳滤组合工艺可大幅提升出水水质,可满足不同用途的再生水水质需求。
    基于上述优化的纳滤膜城市污水深度处理工艺操作参数,揭示了不同运行时长的纳滤膜污染特征,优化了膜污染清洗策略。膜污染物以亲水性有机物为主,膜面由亲水→疏水→弱亲水,大分子蛋白质类物质随运行时间逐渐成为不可逆膜污染的主要贡献者,无机盐类物质(Ca, S, P, Al)随运行时间逐渐积累,并通过与有机物形成的滤饼层加剧膜污染。碱洗+酸洗组合方式的膜污染清洗效果最佳,其中44 h 组中ALK1 组合+酸洗(方法E)效果优于ALK2 组合+酸洗(方法F),而92 h 组中方法F 效果更佳。因此,运行周期以及针对有机污染选取的清洗策略对纳滤膜污染控制十分关键。
     本研究开展了基于NF 浓水回流的预处理-纳滤(MBR-NF)组合工艺用于纺织废水深度处理与回用的中试研究,结果表明,与原工艺好氧段比较,MBR 大幅缩短了好氧段HRT,可节省占地面积,提高处理效率。在高NF 浓水回流比下(90%),盐度积累对MBR 的处理效果和污泥活性有一定的负面影响,并导致MBR 膜污染加剧,但NF 工艺的稳定运行保证了出水水质可以满足不同用途再生水水质的要求。NF 浓水回流引起了MBR 中微生物群落结构的显著变化,主要体现在微生物种类和丰度的减少、污泥中无机盐结晶的出现。MBR 段污泥上
清液中SMP 总含量和LB-EPS 中腐植酸含量的变化是导致MBR 中膜污染的主要影响因素,而NF 膜的主要不可逆污染物为蛋白质类物质以及Ca2+、Mg2+、SO42-形成的无机盐结垢,因此宜采取先碱洗后酸洗的纳滤膜清洗策略。
英文摘要:     Nanofiltration (NF) is being paid more attention to its research and application in wastewater treatment and reclamation recently. The membrane selection, optimization of NF operational parameters, membrane fouling and its cleaning strategy of NF, as well as a field pilot-scale study of MBR-NF were carried out in this study for the advanced treatment of municipal wastewater and typical industrial wastewater, in order to provide technical support for upgrading of municipal wastewater treatment plants and industrial wastewater advanced treatment in industrial parks.
    The membrane selection and its operational optimization of NF for advanced treatment of municipal wastewater were carried out based on a U15 (54×31) mixed-level uniform design and a L9 (34) orthogonal design experiments. The optimized results were achieved at TMP=12 bar, pH=4, flow rate=8 L/min, T=30 oC using DK membrane from GE. The water quality of NF permeate could meet the requirements of water reuse standards for different uses, much better than the effluents from oxidation ditch and UF following. The combination of NF with oxidation ditch was proved to be more efficient for pollutants removal and water reuse.
    Membrane fouling experiments with different durations were designed to investigate membrane fouling and optimize membrane cleaning. Results of foulants analysis showed that proteins with high molecular weight were the main contributor for the irreversible membrane fouling with the increase of duration, while inorganic foulants were mainly embedded into the cake layer formed by organic foulants. Hydrophilic organic foulants were the main contributors for membrane fouling in municipal wastewater advanced treatment. The morphological structure and hydrophilicity of membrane surface changed greatly with operational duration. The hydrophilicity of membrane varied from hydrophilicity to hydrophobicity, then turned to weak hydrophilicity. Proteins became the dominant composition of foulants for irreversible fouling, while the proposition of inorganic salts increased. The combination of alkaline cleaning and acidic cleaning showed the best cleaning efficiency of NF. In 44 h group, ALK1+acid (Method E) was better than ALK2+acid (Method F) while ALK2+acid (Method F) was recommended in 92 h group. It is crucial to select an appropriate operational duration and targeted cleaning strategy for membrane fouling control.
    MBR-NF combined process with the NF concentrate recycling to the MBR was used for advanced treatment of textile wastewater in pilot scale. MBR showed great advantages in comparison with traditional aerobic process, which significantly reduced HRT and provided high removal efficiency. Salinity in NF concentrate caused negative influence on the performance of MBR and the activity of sludge in MBR, while NF guaranteed the permeate water quality could meet the requirements for water reuse. The recycle of NF concentrate caused significant impact on microbial community structure and the crystals precipitated in sludge. The soluble microbial products (SMP) concentration and proportion of humic acid in LB-EPS were the key factors of membrane fouling in MBR, while proteins and inorganic salts containing Ca2+, Mg2+ and SO42- were the dominant contributors for the irreversible fouling of NF. And alkaline cleaning followed by acid cleaning was considered to be an appropriate cleaning strategy of NF.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36877
Appears in Collections:水污染控制技术研究室_学位论文

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Recommended Citation:
李昆. 纳滤膜在城市污水与工业废水回用中的应用及其膜 污染控制研究[D]. 北京. 中国科学院研究生院. 2016.
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