【作者】 潘洁；

【导师】 鲍建国； 李民敬；

【作者基本信息】 中国地质大学 ， 环境科学与工程， 2010， 硕士

【摘要】 再生水是指污水经过适当处理后,达到一定的水质指标,满足某种使用要求,可以进行有益使用的水。同海水淡化、跨流域调水相比,再生水具有明显的优势。从经济角度看,再生水的处理成本低；从环保角度看,污水再生利用有助于改善生态环境,实现水生态的良性循环。再生水是城市的第二水源,将再生水深度处理后回灌到地下,不但可以防止海水入侵、地面沉降,而且可以补给地下水资源,缓解水资源紧缺的矛盾,是贯彻可持续发展的重要措施。再生水在回灌地下之前需要经过一定的处理,达到《城市污水再生利用地下水回灌水质》(GB／T 19772-2005)中的标准限值才可以进行回灌。再生水的深度处理工艺主要包括絮凝、过滤、吸附、反渗透、消毒。虽然工艺已经比较成熟,但是在絮凝剂的选择,特别是新型絮凝剂的研发、过滤滤料和吸附剂的选择等方面还可以进行更为深入的研究。此外,对再生水深度处理的工艺技术集成也有待进一步研究。本论文以武汉市某城市污水处理厂二级出水为研究对象,以处理后回灌地下为研究目的,对天然矿物改性作絮凝剂、以适用于再生水的深度处理进行研究,规避使用传统絮凝剂后对水体造成二次污染或致毒的风险。实验内容包括：适用于再生水深度处理的膨润土改性方案、适用改性方案的参数优化、最佳污水处理参数的选取。最后以武汉某城市污水处理厂二级出水为处理对象,将已得成果应用于室内中试模拟实验。实验将PAC作为对比絮凝剂,研究改性膨润土用于污水深度处理一体化装置对污水的处理效果,判断其回灌地下的可行性,为野外实验基地工作的顺利开展提供理工基础和实验依据。通过实验,得到如下重要结论：1、选取焙烧活化(马弗炉焙烧、微波焙烧)、酸活化、铝柱撑改性、微波协同硫酸亚铁改性这四种常见的膨润土改性方案,确定适用于再生水深度处理的膨润土改性方案。通过实验研究得出结论：马弗炉焙烧和微波焙烧活化的改性产物,对再生水的处理效果较差,几乎不能对污水中的有机物和总磷进行去除；铝柱撑改性的产物对污水中的有机物及总磷有一定的去除效果,值得注意的是,再加入了微波活化的铝柱撑改性产物对污水中总磷的去除能力十分显著,说明微波对膨润土改性起着重要的作用；微波协同硫酸亚铁改性产物对有机物和总磷的去除效果最好,其去除率可达50%、20%左右。从微观结构分析,数据证明微波协同硫酸亚铁的改性方案能够有效增大膨润土的层间距,使其具有更强的吸附能力。故确定微波协同硫酸亚铁改性工艺为最佳膨润土改性方案。2、实验对微波协同硫酸亚铁改性膨润土的工艺参数进行深入研究,探讨改性剂浓度、固液比、微波辐照功率、微波辐照时间对改性产品吸附性能的影响。实验得出：改性剂浓度、固液比、微波辐照时间对改性膨润土吸附性能的影响较大。改性剂浓度直接影响改性基团的大小和种类,从而影响膨润土的比表面积,由此决定改性产物吸附性能的强弱；固液比同样影响改性基团的浓度,若反应不充分,则会导致改性产物的吸附性能降低；微波加热能够在短时间内针对膨润土的内部分子进行加热,疏通孔道,使其失去层间水和结合水。但当微波辐照时间过长时,膨润土内部可能形成卷边,分子结构崩塌,从而影响改性膨润土对污水的处理效果。而微波辐照功率对改性膨润土吸附性能的影响不大。因此,最佳的改性参数为：改性剂浓度为0.75mol／L,固液比为1：9,微波辐照功率为420W,微波辐照时间为5min。3、实验将上述实验研发的改性膨润土应用于污水处理,优化其使用参数,包括改性膨润土投加量、混凝时间、pH及温度。实验得出：改性膨润土最佳投加量为1.4g／L,最佳混凝时长为5min,pH宜控制在7～8的范围内,在室温或接近室温的条件下处理污水最为有效。4、实验集成已得的研究成果,将改性膨润土、纤维球和MWB型活性炭应用于室内中试实验,并按照野外实验基地的实际参数制造出一套再生水预处理和深度处理一体化装置。实验证明：该模拟装置对污水中的悬浮物、有机物及总磷污染物的去除率均高于80%,出水除氮类污染物没有达到回灌标准限制外,其他指标均低于国标要求的限值。分析原因,可能由于进水水质和装置条件不利于硝化细菌的生长。同时,该室内中试还模拟了过滤、吸附柱的反冲洗步骤,实验证明一体化装置在多次反冲洗前后,能保持稳定运行,出水水质良好,无较大波动。5、经计算得出,项目的运行成本为0.71元／m3污水。虽然稍贵于使用PAC作絮凝剂时的运行成本,但处理后产生的改性膨润土污泥可用于建筑材料、回填衬层等领域。并且改性膨润土作为一种新型天然矿物絮凝剂能在短时间自行沉降,真正具备了絮凝剂的基本性能,为今后的实验研究奠定了一定的理论和实践基础。6、实验研究了微波协同硫酸亚铁改性提高膨润土吸附性能的机理：改性剂中的铁离子平衡了硅氧四面体上的负电荷,从而使层间的阳离子具有可交换性,因而增强了膨润土对阳离子的吸附能力。并且游离出的铁离子还能与污染物发生混凝反应,进而去除更多的污染物。另外,微波辐照能使得膨润土的晶体结构排列的更为紧密,增强其化学稳定性,从而能适用于不同的应用领域。更多还原

【Abstract】 Reclaimed water is a kind of water which can reach to a certain degree of water quality objectives, meet certain application requirements and can be used beneficially. Compared to seawater desalination and inter-basin water transfer, reclaimed water has obvious advantages. From the economy point of view, the treatment cost of reclaimed water is lower. From the environmental protection point of view, recycling of sewage contribute to the improvement of the ecological environment and to achieve a virtuous circle of aquatic ecosystems. Reclaimed water is the second water source of a city. Reclaimed water recharge to groundwater after advanced treatment not only can prevent seawater intrusion and land subsidence, but can also supply the groundwater resources, alleviate the shortage of water resources conflicts. It is an important measure carrying out the sustainable development.Reclaimed water need to go through some processes, reach to the standard "The reuse of urban recycling water, Water quality standard for groundwater recharge" (GB/T 19772-2005) before recharged to groundwater. The pre-treatment and deep treatment processes for reclaimed water mainly include coagulation, filtration, adsorption, reverse osmosis and disinfection. Although the processes have been more mature, but on the aspects of coagulant selection, especially the research on the new type of coagulant, filtration media selection and the type of adsorbent etc, are needed. In addition, the research on the integration of different processes need to be improved.Taking secondary effluent of a sewage treatment plant in WuHan as study object,groundwater recharge as the aim, the article research on modified natural mineral as coagulant used on pre-processing and deep processing. Using the new type of natural mineral coagulant could avoid secondary pollution and toxicity compaired with the traditional coagulants. The content of the research include:the appropriate program of modified bentonite to pre-processing and deep processing of reclaimed water, the best conditions of modified program and wastewater treatment. Finally, using secondary effluent as object, the research combine pre-treatment and deep treatment processes to study the effections by using modified bentonite as coagulant, comparied with PAC. On this basis, we could determine the feasibility of underground recharge, meanwhile, provide theoretical foundation and parameter reference for field test.Through the experiment, the following results and conclusions are gained:First:Select the most appropriate program of modified bentonite to pre-processing and deep processing of reclaimed water among roasting activation (muffle furnace calcination and microwave heating), acid activation, modification of Al-pillared and modification of micro-Ferrous sulfate.The products of roasting activation can hardly remove pollutants. The product of Al-pillared modification can partly remove the pollutants. It is worth noting that the micro-Al-pillared modified bentonite has the strong removal capacity to total phosphorus, this could explain the important role of microwave towards the modification of bentonite. The treatment effect of secondary effluent by using micro-Ferrous sulfate modified bentonite is the best, the removal rates of organic and total phosphorus are about 50% and 20%. The analysis of microstructure improve that the program of micro-Ferrous sulfate can expand the interlayer spacing of bentonite effectively and increase its adsorption capacity. Therefore, the program of micro-Ferrous sulfate is the most appropriate program to pre-processing and deep processing of reclaimed water.Second:The article conducts in-depth study of best conditions of modified program, including the influences of the concentration of modifier, the ratio of solid to liquid, the power and time of microwave irradiation to the adsorption capacity of modified bentonie. The results show that the concentration of modifier, the ratio of solid to liquid and the time of microwave irradiation effect its adsorption capacity. The concentration of modifier can directly effect the size and variety of modified group, and effect the ratio suface of bentonite as a result, and decide the degree of strength of modified product’s adsorption capacity. The ratio of solid and liquid could effect the concentration of modifier as well, if happen a inadequate response, the adsorption capacity of modified product may weaken. Microwave can heat the intra-molecule of bentonite in a very short time, dredge its channel and remove its interlayer water and bound water. But, when the time of microwave irradiation is too long, curling and collapse of molecular structure will happen in the inner part of bentonite, and affect the effect of sewage treatment by using the modified bentonite. In the other hand, the power of microwave irradiation nearly has the effect to the adsorption capacity of modifed bentonite. Hence, the best conditions of modified program are:the concentration of modifier is 0.75mol/L, the ratio of solid to liquid is 1:9, the power and time of microwave irradiation are 420W and 5min. Third:The research use the best modified poduct on sewage treatment, and optimize its operation parameters.The result shows:when the dosage of modified bentonite is 1.4g/L, the adsorption time is 5min, the range of pH is 7 to 8, and the temperture is about room temperature, the effection of sewage treatment is the best.Fourth:The research integrate the obtained results (included modified bentonite,fiber ball filtration and MWB activated carbon) in the indorr pilot experiment, and product a set of pre-processing and deep processing integrated device compaired to the actual device in our field experiment base.The result shows:the integrated device can effectively remove the SS, organic and total phosphorus of sewage effluent water, and the removal rates are all higher than 80%. The effluent quality almost reach the limit of recharge standard except nitrogen pollutants. The water quality and the conditions of the integrated device are not conductive to the growing of nitrifying bacteria, this may be the reason of the low removal rate of nitrogen pollutants. At the same time, the research simulate the anti-washing step of filtration and activated carbon part.lt shows that after several times of anti-washing, the integrated device can operate stablely, and effluent quality are good without large fluctuations.Fifth:Through calculated, the project’s operating cost is 0.71 yuan er cubic meter wastewater. Although the cost is a little bit higher than the cost by using PAC as the coagulation, the sludge of modified bentonite could be used in many different ways,like producing building materials or used in backfill lining. As the new type of natural mineral coagulant, it can realize self-settlement in a very short time, and truly have the basic ability of coagulation.This apply a theoretical and practical basis for future experimental research.Sixth:The research also study on the mechanism of micro-Ferrous sulfate modification.lt maybe work in this way:the iron ion from modifier could balance the negative charges on silico-oxygen tetrahedron, and make the cations from interlayer have the exchangeable ability.Thus, the adsorption capacity of bentonite is enhanced.On the other hand, some free iron ion could occur coagulation with pollutants, this will remove much more pollutants and increase the quality of water. Besides that, microwave irradiation can re-arrange the crystal structure of bentonite and make it more closely. This can increase the chemical stability of modified bentonite, and expand its applications.更多还原