【作者】 徐娟；

【导师】 盛国平；

【作者基本信息】 中国科学技术大学 ， 环境工程， 2010， 硕士

【摘要】 生物处理是目前废水处理的重要手段之一。微生物在降解废水基质的同时,会产生一类大分子物质—溶解性微生物产物(soluble microbial products,SMP),是运行良好的生物处理系统出水中残留的化学需氧量(chemical oxygen demand,COD)的主要组分,它的存在决定了系统对COD的去除效率,直接关系着出水能否达到排放标准。本论文系统研究了废水处理过程中SMP的形成规律及影响因素,深入探讨了SMP的螯合特性,探索了活性污泥及其胞外多聚物(Extracellular polymeric substances , EPS)对典型药物及个人护理品(pharmaceuticals and personal care products,PPCPs)的吸附作用。主要研究内容和研究结果如下:1.应用响应曲面方法(response surface methodology,RSM)结合灰关联分析(grey relational analysis,GRA)研究进水底物浓度,氨氮浓度,温度和曝气速率对SMP生成的影响。研究结果表明:当在优化的操作条件下(碳源浓度654.8mgCOD/L,氨氮浓度23.9mg/L,温度13.7℃,曝气速率0.1m3/h),可以得到较小的SMP产出量为7.5mg/L。这四个因素对SMP产出的影响权重遵循:温度>碳源浓度>曝气速率>氨氮浓度。多糖是出水SMP的主要组成部分。2.用三维激发发射矩阵(Three-dimensional excitation-emission matrix,EEM)荧光猝灭结合自加权交替三线性分析(self-weighted alternating trilinear decomposition,SWATLD)研究了SMP与三种常见金属(Cu2+,Al3+,Fe3+)间的相互作用。结果表明:SMP中的蛋白和腐殖类物质对于这三种金属都有很强的络合作用,且对Cu2+>Al3+>Fe3+。相比较腐殖质,蛋白对这几种金属有更强的亲和性;SMP与金属的络合反应受溶液pH值影响明显。在偏中性条件下SMP的络合性能较强,而在过酸过碱条件下,均不利于络合反应的进行。离子强度对SMP的络合性能影响较为复杂,在不同的离子强度区域内产生不同的影响。3.从热力学和动力学角度研究了污泥絮体及其EPS对三氯生(Triclosan,TCS)的吸附作用,并初步探索了三氯生对微生物体系的影响。研究发现:活性污泥絮体对三氯生的吸附过程符合Lagergren动力学模型和Freundlich吸附模型;EPS通过疏水性作用吸附三氯生,属于物理吸附范畴;LB(Loosely bound)-EPS,TB(Tightly bound)-EPS与三氯生发生疏水性作用的基团有所不同,TB对于三氯生的结合能力略强于LB,结合作用受pH的影响不明显;三氯生在短时间内对微生物毒性不明显,一定程度上能够提高新陈代谢,同时会刺激微生物分泌更多的SMP。更多还原

【Abstract】 Biological treatment is one of the most widely used wastewater treatment processes. Soluble microbial products (SMP) are produced by the microorganisms in wastewater treatment bioreactors when organic materials presented in wastewater are consumed. SMP constitute a major part of the residual chemical oxygen demand (COD) in effluent for most well-operated biological treatment system. Hence, the presence of SMP is a matter of great interest not only because they effectively control the removal efficiency for COD, but also in terms of achieving current discharge standards. In this paper, the formation rule and influencing factors of SMP were explored. Cheating characteristics of SMP were also studied in depth. The preliminary research on the adsorption characteristics of typical pharmaceuticals and personal care products (PPCPs) on activated sludge and EPS was developed as well. Main contents and results are as follows:1. RSM coupled with GRA were used to evaluate both the individual and interactive effects of substrate concentration, NH4+-N concentration, temperature and aeration rate on SMP production. Results show that a minimum SMP production of 7.5 mg/L was obtained under the optimum conditions: substrate concentration 654.8 mg COD/L, NH4+-N concentration 23.9 mg/L, temperature 13.7oC, aeration rate 0.1 m3/h. GRA analysis results show that the influential priority of the four factors on the SMP production is: temperature> substrate concentration> aeration rate> NH4+-N concentration. Carbonhydrates were found to be the major component of SMP in SBR system.2. The interactions between three metals and SMP of the effluent from wastewater biological treatment plant were investigated by fluorescence quenching combined with EEM fluorescence spectroscopy and SWATLD analysis. The main conclusions are as follows: Both protein- and humic-like substances in SMP were strong ligands for the three metals, with an order of Cu2+>Al3+>Fe3+. All the three metals had a better affinity to protein-like substance compared to humic-like substance in SMP; The complexation between metals and SMP could be significantly affected by solution pH values. SMP had relatively higher affinity to the metals at neutral condition than those at acidic or alkaline conditions. However, ionic strength influenced the complexation of SMP by a complicated mechanism. Different effects occurred at various ionic strength region.3. The adsorption characteristics of triclosan on activated sludge and EPS were studied mainly based on thermodynamics and dynamics. In addition, some preliminary explorations on biotoxiacity of TCS to the biological wastewater treatment were carried out. It was found out that the adsorption process of activated sludge floc tailed with Lagergren dynamical model and Freundlich adsorption model. The adsorption of TCS on EPS is physical adsorption attributed to the interaction between hydrophobic functional groups. The functional groups which interacted with TCS vary between LB and TB, and TB has a relatively higher affinity to TCS compared with LB. This interaction is slightly influenced by the pH of the solution. Biotoxiacity of TCS to microorganisms is not clear, however, the metabolism of the activated sludge is enhanced to a certain degree. At the same time, more SMP is produced reflecting a response to the outside pressure.更多还原