| 题名 | 在线混凝-超滤组合工艺处理微污物研究 |
| 作者 | 宋婷婷 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 赵长伟 |
| 关键词 | 在线混凝-超滤 微污染物 膜污染 絮体特性 Inline coagulation-ultrafiltration micropollutants membrane fouling flocs characteristics |
| 其他题名 | in-line coagulation-ultrafiltration process for treatment of micropollutants |
| 学位专业 | 环境工程 |
| 中文摘要 | 本文采用在线混凝-超滤组合处理工艺开展对微污染水的实验研究，系统深入地研究了混凝剂类型以及有机物的组成对在线混凝 -超滤组合工艺中膜污染的影响。取得创新性研究成果如下： 1.研究考察了混凝剂种类和投加量对混凝过程中腐殖酸去除效果的影响并确定各自最佳混凝投加量，随后研究不同的混凝剂对在线混凝-超滤组合工艺中膜通量变化的影响。实验确定了最佳混凝剂类型和最佳投加量投加量为0.60mmol/L AlCl3。通过考察混凝出水中絮体尺寸与结构并利用污染膜模型对膜污染过程进行分析，研究表明在线混凝-超滤组合工艺中的超滤膜污染主要受絮体特性的影响，而超滤膜的絮体膜污染机理主要为滤饼层阻力。 2.研究蛋白质类物质-牛血清蛋白与腐殖酸共存时，有机物组成的变化对混凝-超滤组合工艺中膜污染的影响。BSA的存在，明显降低了混凝过程的絮体粒度，而且当 HA与 BSA的共存时，虽然破碎后絮体的恢复能力有所提高，但絮体的强度则有所降低，这可能是因为 BSA与 HA共存时，在疏水性相互作用下，HA会吸附疏水性有机物 BSA形成 HA-BSA聚合物，而且随着有机物配比的不同，HA与 BSA吸附程度也不同，HA-BSA聚合物的形成直接影响了后续的混凝过程的絮体特性。因此，BSA的存在阻碍了混凝过程。BSA的存在，对组合工艺中的膜通量和膜附近絮体的水动力学行为也存在不利的影响。当 HA单独存在时，膜通量衰减最轻，实验结束时，相对膜通量减小为0.8。而当 HA：BSA=1:3时的膜通量衰减情况要大于 HA：BSA=3:1时的膜通量衰减。当 BSA单独存在时，膜通量衰减最为严重，实验结束时，相对膜通量衰减为 0.6。通过分析膜附近絮体水动力学行为变化情况，可以看出，随着有机物组成中 BSA比例的升高，膜表面的低流速区域随运行时间延长向外扩张速度减小，而膜周围的絮体速度出现明显地衰减，说明膜表面的滤饼层作用减弱，浓差极化现象不断加剧。当单一投加 BSA时，膜表面的边界层厚度随时间没有出现明显的扩张，结合 SEM图片可以看出膜表面没有出现一定厚度的滤饼层，而膜周围的絮体速度则随着浓差极化现象的加剧而不断减小，初始的最大速度由 0.0034m/s降为 0.0018m/s。进一步分析流体的紊流度随时间变化情况，也可以看出，随着有机物组成中 BSA比例的升高，流体的紊流度随时间几乎没有增加，而当单一投加 HA时，流体紊流度随时间变化出现明显的增加趋势。因此，BSA的存在严重的降低了混凝的功效，阻碍疏松滤饼层的形成，从而使得在线混凝-超滤组合工艺的膜污染加剧，同时恶化膜表面的水力条件，而较差的水利条件进一步加剧组合工艺中的膜污染现象。 3.研究考察了多糖类物质-褐藻酸与腐殖酸共存时，有机物组成的变化对混凝-超滤组合工艺中膜污染的影响。结果表明在混凝过程中，随着褐藻酸在有机物组成比例中的增加，由于褐藻酸的吸附架桥作用形成的絮体尺寸远大于单一投加腐殖酸时的絮体，且絮体的强度和可恢复性能也被改善，从而使得在线混凝-超滤组合工艺中，随着褐藻酸比例的增加，膜污染逐渐减轻，膜通量衰减由单一投加腐殖酸时的 0.8上升到 HA：SA=1:3时的 0.94。为进一步研究不同有机物组成条件下的絮体特性对膜表面水动力特性的影响，通过在线混凝-超滤 PIV实验，得出随着有机物组成中褐藻酸比例的增加，随运行时间的延长，膜表面的低速区域明显向外扩张，说明滤饼层厚度显著增加，且膜附近的紊流度急剧的升高，膜表面水动力条件显著改善。这主要是由于 SA存在条件下的絮体特性决定的。 |
| 英文摘要 | In this paper, it was investigated that inline coagulation –ultrafiltration for the treatment of micropolluted raw water, experiments were carried out to investigate the effect of the coagulant type and the organic composition on the membrane fouling in the inline coagulation-ultrafiltration. The main conclusion are as follows: 1. The effect of coagulation species and dosage on removal efficiency of humic acid (HA) was investigated and then the optimal coagulants dosage were determined, whereafter, the effect of the coagulants type on the membrane flux in the integrated process were investigated. The experiments determined the optimal coagulants specie and dosage were AlCl3 and 0.60mmol/L, respectivly. Through measuring floc characteristic (size and structure) and analysising membrane fouling model, it can be determined that ultrafiltration fouling was mainly affected by floc size and fouling mechanism was cake resistance on membrane surface. 2. the effect of composition of humic acid (HA) and the Polysaccharide substance-alginate（SA）on the membrane fouling in the integrated process were investigated .The results showed that due to the Adsorption bridging role of the alginate ,the flocs size greater than the HA flocs, the strength and the recoverable performance were also improved, so as to the membrane fouling was mitigated with the increasing of the proportion of the alginate in the integrated process. The normalized permeate flux (J/J0) rised to 0.94 from 0.8. The PIV experiment was were carried out to investigate the hydrodynamic performance around the hollow fiber membrane. The results showed that the low flow velocity was gradually expanded and the turbulence was improved with the running time due to the different flocs performance. 3. the effect of composition of humic acid (HA) and the proteins-bovine serum albumin（BSA）on the membrane fouling in the integrated process were investigated . The results showed that the flocs size was obviously decreased due to the BSA, and when the HA and BSA were coexistent, although the broken flocs’ recovery capability was improved, the flocs’ strength were decreased due to the HA-BSA polymer in the hydrophobic interaction. And the sorption ability for the HA and BSA was different with the organics composition. The HA-BSA polymer effected the flocs characteristics in the coagulation process. So the BSA obstructed the coagulation. The BSA also effected the membrane flux and the flocs hydrodynamic performance. The only HA had the least membrane fouling ,and the J/J0 decreased to 0.8. However, the only BSA had the most membrane fouling ,and the J/J0 decreased to 0.6. the flocs hydrodynamic performances were also changed, the expansion velocity of the low flow velocity filed and the flocs velocity around the membrane were decreased with the increasing of BSA, which illustrated the cake layer was decreased and the concentration polarization was aggravated. and the turbulence intensity was not obvious increasing with the running time due to the existence of the BSA . So the presesnce of BSA seriously degrades the efficiency of the coagulation and the formation of the cake layer and the hydraulic condition on the membrane surface. |
| 公开日期 | 2015-07-08 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15732]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 宋婷婷. 在线混凝-超滤组合工艺处理微污物研究[D]. 北京. 中国科学院研究生院. 2014. |
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