【作者】 赵如金；

【导师】 吴春笃；

【作者基本信息】 江苏大学 ， 环境工程， 2009， 博士

【摘要】 膜生物反应器是将生物处理工艺与膜分离技术相结合而成的一种新型、高效污水处理技术，是中水回用的热点处理工艺。该工艺具有出水水质好、耐冲击负荷、剩余污泥少及占地面积小等优点。在污水排放标准越来越严格和水资源短缺问题日益突出的背景下，膜生物反应器将成为污水处理与资源化的重要技术途径之一。但膜生物反应器技术目前还存在膜污染、能耗大、费用高等问题。已有的研究多通过优化运行参数、添加PAC填料、采用组合工艺等措施提高污染物去除率，有些措施还能有效减缓膜污染。但向膜生物反应器中添加廉价的铁氧体粉末及采用低温等离子体技术对膜进行改性，以提高污水中污染物去除率及改善膜污染的系统研究尚不多见。在上述背景下，设计制作铁氧体粉末膜生物反应器（PF-MBR），组建实验系统；并对城市生活污水进行处理，研究各主要运行参数对污染物去除效果及膜污染的影响规律；考察铁氧体粉末添加对污水中污染物去除效果及膜污染的影响，并进行了PF-MBR处理城市生活污水的动力学分析；在此基础上采用低温等离子体对聚偏氟乙烯膜进行改性，研究低温等离子体改性对污染物去除率及膜耐污性能的影响。实验结果表明，采用自制的PF-MBR处理生活污水时，反应器中DO、HRT、MLSS、进水pH及温度等对污水中COD、NH₄⁺-N、TN及TP的去除均有一定的影响；膜生物反应器中添加铁氧体粉未能明显提高生物反应器对COD及NH₄⁺-N的去除率，但对TN和TP的去除效果影响不大；添加铁氧体粉末能在一定程度上延缓膜污染。一定条件下，膜生物反应器运行到第30天时，不加铁氧体粉末的MBRB膜过滤压差达到22．9kPa，而添加铁氧体粉末的MBRA膜过滤压差只有1 7．2kPa；MBRA的膜过滤阻力比MBRB小1．65×10¹²m^-1,，其中，MBRA由膜孔堵塞与吸附产生的阻力显著小于MBRB；尽管MBRA和MBRB的临界通量均介于17-20L／（m²·h）之间，但当膜生物反应器以20L／（m²·h）的膜通量运行时，MBRB膜过滤压差的增长速率为0．06kPa／min，明显大于MBRA。通过正交实验得到因素铁氧体粉术投加量A、铁氧体粉末比饱和磁化强度B、膜通量C和曝气量D对COD去除率、NH₄⁺-N去除率及膜过滤阻力上升速率影响的重要性顺序。PF-MBR运行的较优水平是A₃B₃C₁D₂。机理分析表明，膜生物反应器中加入铁氧体粉末后，在微生物降解、磁场能、铁氧体粉术吸附等共同作用下，实现了污水中污染物去除率的提高；同时，铁氧体粉末的加入改变了活性污泥絮体的结构和性质，降低了膜生物反应器运行过程中膜表面泥饼层产生的阻力及膜孔堵塞与吸附产生的阻力，从而有效缓解膜污染。动力学分析结果显示，PF-MBR处理城市生活污水时，有机底物降解动力学常数K的平均值为0．0023 L／（mg·d），大于不加铁氧体粉末膜生物反应器的有机底物降解动力学常数；PF-MBR处理城市生活污水时，污泥增殖的动力学模式为：（?）=0．2502（?）-0．0371，产率系数y为0．2502，衰减系数K_d为0．0371。低温等离子体改性对PF-MBR去除污染物效果的影响不大，但能增强膜的耐污染性能。在稳定运行过程中，改性膜过滤压差增加的速率明显小于非改性膜；改性膜的过滤总阻力、膜本身的固有阻力、膜表面泥饼层所产生的阻力及膜孔堵塞与吸附所产生的阻力均小于非改性膜；在相同操作条件下，改性膜的临界通量为20～23L／（m²·h），高于非改性膜。机理分析表明，膜的低温等离子体改性可以在膜表面引入大量羟基、羰基等亲水性极性基团，使膜表面受到刻蚀，粗糙度增加，从而使膜表面的亲水性增强，耐污性能得到提高。研究中采用低温等离子体进行膜改性，能明显增强膜的耐污染性能，同时具有高效、低成本、环保等优点。所采用的磁性铁氧体粉末可以从重金属废水中在一定条件下直接获得。该填料的加入在提高污染物去除率及改善膜污染的同时，还可实现废物的综合利用，体现了资源化的技术政策。因此，该研究具有重要的意义及较大的推广应用价值。更多还原

【Abstract】 Membrane bioreactor（MBR） is a new efficient technology of sewage treatment, which combines biological treatment with membrane separation process. It is the hot spot of reuse process of reclaimed water. MBR has many advantages, such as good effluent quality, strong resistant capability to impact loading, little excessive sluge, small area occupied. Wastewater discharge standard is more and more strict. At the same time water resources shortage is becoming increasingly conspicuous. Under the circumstances, MBR will be one of the important technologies for sewage treatment and recycling. But MBR faces some problems such as membrane fouling, high energy consumption and high running expense. In existing research the removal rates of pollutants increase usually by optimizing running parameters, adding PAC filling, using combined process, etc. Some of the measures can also lighten membrane fouling. But systematic researches on raising the removal rates of pollutants and controlling membrane fouling are rare by adding cheap powdered ferrite and modifying membrane using low temperature plasma technology.Under the background, PF-MBR （MBR with powdered ferrite added） is designed and made. And experimental system is established. The effect laws of main running parameters on the removal efficiency of pollutants and membrane fouling are studied when treating urban domestic wastewater with the self-made PF-MBR. The effect of adding powdered ferrite on the removal efficiency of pollutants and membrane fouling is researched. The kinetics of treating municipal wastewater with PF-MBR is discussed. On this basis, polyvinylidene fluoride （PVDF） membrane is modified with low temperature plasma. And the effect of the modification on the removal rates of pollutants and anti-fouling property of membrane is researched.The results show that DO, HRT, MLSS, influent pH and temperature influence the removal of COD, NH₄⁺-N, TN and TP in sewage when treating domestic wastewater with the self-made PF-MBR. When magnetic powdered ferrite is added in MBR, the removal rates of COD and NH₄⁺-N increase obviously. But the removal of TN and TP is not obviously affected by the addition of magnetic powdered ferrite. Adding magnetic powdered ferrite can lessen membrane fouling to a certain extent. On the thirtieth day of stable operation, the transmembrane pressure of MBRB without powdered ferrite added is 22.9kPa. The transmembrane pressure of MBRA with powdered ferrite added is 17.2kPa. The membrane filtration resistance of MBRA is less than that of MBRB by 1.65×10¹²m^-1, in which the resistance from membrane pore plugging and adsorption of MBRA is markedly less than that of MBRB. Although critical fluxes of both MBRA and MBRB are 17～20IV（m²·h） under the given conditions, the growth rate of transmembrane pressure in MBRB is obviously more than in MBRA when running flux is 20L/（m²·J）. It is 0.06kPa/min. The importance sequence of the dosage of powdered ferrite （A）, the specific saturation magnetization of powdered ferrite （B）, membrane flux（C） and aeration intensity（D） is arrived at through orthogonal experiments, which influence the removal rates of COD and NH₄⁺-N, the increasing rate of membrane filtration resistance. The optimum operation parameters are A₃B₃C₁D₂ when PF-MBR operates steadily.Mechanism analysis shows that the increasingof the removal rates of pollutants is due to the combined action of microbial degradation, the adsorption of powdered ferrite and magnetic field energy after adding powdered ferrite to MBR. Besides, the addition of powdered ferrite changes the structure and property of activated sludge floc and make the cake layer resistance and the resistance from membrane pore plugging and adsorption decrease. So membrane fouling is alleviated.Kinetic analysis shows that the average value of kinetic constants of substrate degradation is 0.0023 L/（mg·d） when PF-MBR treating municipal wastewater. It is more than the kinetic constant of substrate degradation in MBR without powdered ferrite. When PF-MBR treats municipal wastewater, the kinetic equation of sludgegrowth is Yield coefficient and decay coefficientare 0.2502 and 0.0371 respectively.The modification of membrane with low temperature plasma has no significant effect on the removal rates of pollutants. But it can improve the anti-fouling property of PVDF hollow fiber membrane. During stable operation, the increasing rate of transmembrane pressure of modified membrane is less than that of unmodified membrane markedly. The total resistance, intrinsic resistance of membrane, cake layer resistance and resistance from membrane pore plugging and adsorption of modified membrane are less than those of unmodified membrane. Under the same given conditions, the critical flux of modified membrane is 20～23L/（m²·h）, which is more than it of unmodified membrane. Mechanism analysis indicates that a lot of hydrophilic polar groups such as hydroxyl, carbonyl, etc can be introduced onto the surface of membrane by modification with low temperature plasma. Meanwhile the modification can erode the surface of membrane and increase surface roughness. So the hydrophilicity and anti-fouling property of membrane are improved.PVDF membrane is modified by low temperature plasma in research, which can improve the anti-fouling property of membrane. The modification method has the advantages of high efficiency, low cost and less pollution, etc. The magnetic powdered ferrite used in the experiment may be gained from the wastewater containing heavy metals under certain conditions. The addition of powdered ferrite in MBR can increase the removal efficiency of pollutants and lighten membrane fouling. Furthermore, it materializes comprehensive utilization of wastes and incarnate the technology policy of recycling. So the research is important and has the value of application and extension.更多还原