【作者】 林冲；

【导师】 韦朝海；

【作者基本信息】 华南理工大学 ， 环境科学与工程， 2014， 博士

【摘要】 焦化废水是一种有机质构成复杂、污染物分子结构特异的典型工业废水，已成为水污染控制中的一个难题。虽然经过多级水处理过程，可使焦化废水达到国家的排放标准，但是外排达标水中依然存在TOC约30mg·L-1的有机组分，也构成了对生态环境及人类健康的严重威胁。针对焦化废水达标外排水中残留的毒性、活性组分，由于环保法律法规和分析测试技术的限制，对焦化废水外排达标水水质构成特别是其中有机组分的存在缺乏全面的认识，目前采用的焦化废水控制指标不足以反映该类废水的污染特性。对达标外排水中典型有机污染物认识的匮乏使对残留环境行为的评价缺乏深入理解，导致深度处理焦化废水的选择具有盲目性，焦化废水污染依旧是煤化工行业发展的制约因素。本文在焦化废水常规控制指标分析的基础上应用XAD-8、Dowex50和AmbR900树脂多级分离技术和超滤过滤方法，将焦化废水达标排水中的有机物进行分离，利用消毒副产物势能指标评估各组分中残留有机组分的环境风险，通过建立固相萃取富集方法辅以硅胶-氧化铝分离技术，利用GC-MS分析手段对具有高风险的组分中有机物进行全面分析，筛选出具有高风险的消毒副产物前体物特性的有机物。结果表明，大于100kDa组分的有机物和小于1kDa组分的有机物同时具有很高的三卤甲烷（THMs）和卤乙腈(HANs)类消毒副产物生成势能，焦化废水外排水中亲水酸性有机物所占比例最高，约占45%。通过三维荧光光谱分析和GC-MS定性分析，发现焦化废水外排水中含有微生物代谢产物，浓度不高但具有较高的荧光响应。在<1kDa分子量分布的有机物中筛选出约120种消毒副产物前体物，包括腈类、胺类、含氮杂环类含氮消毒副产物前体物以及酚类、烃类、酯类、酸类、醇类、多环芳烃类和含氧杂环类有机化合物等含碳消毒副产物前体物。臭氧（O3）氧化作用可以实现达标外排水中消毒副产物前体物的削减，其削减量与O3的投加量成正比。O3氧化作用将外排水中大分子有机物氧化为小分子，继续对小分子有机物产生矿化作用，将不饱和价键的有机物转变为氯反应惰性的有机物，改变尾水中有机物的官能团结构，使THMs和HANs的总生成潜能大幅度降低，表现为被氧化后外排水中DOC、UV254、SUVA、荧光强度和其他含氮无机组分包括氨氮、氰化物和硫氰化物等的同步降低或去除、O3氧化过程中有机物的种类发生了变化，外排水中主要的含氮有机物包括含氮杂环、腈类等快速被O3氧化，胺类物质出现先增多后减少的过程，随着反应时间的延长也能够被氧化；烯烃、酚类等含不饱和官能团的有机物也能被选择性氧化。O3氧化过程中会形成有机酸类、烷烃类等中间产物，该类物质具有较低的HANs和THMs生成潜能，O3氧化过程可有效减少外排水的环境风险。以焦化废水中具有特殊分子构型的多环芳烃（PAHs）作为研究对象，成功设计和开发了紫外光臭氧流化床反应器应用于处理焦化废水外排水中低浓度多环芳烃（PAHs）。通过条件实验优化，环境风险评估和成本分析表明：紫外光耦合臭氧催化过程可以增强PAHs的降解效率，约为45.4%；方差分析显示pH条件对臭氧氧化的影响具有显著性，碱性条件也有利于提高PAHs的去除率。对目标PAHs的降解过程进行拟一级动力学方程拟合，线性回归系数大于0.920，符合拟一级动力学方程模型。降解速率与初始浓度成正相关关系。在连续运行条件下，水力停留时间为2h时，紫外光臭氧流化床可以削减毒性当量为0.432g·L-1的致癌物质进入地表水环境，此时需要$0.16每吨水的处理费用，占整个污水处理站运行费用的13.5%左右。利用焦化污泥作为研究对象，对比臭氧流化床反应器在两相和三相中的处理效率，分析污泥中残留的PAHs同步降解过程。该过程受到臭氧投加量、过氧化氢（H2O2）投加量和pH的影响。随着臭氧投加量的增加，多环芳烃的分解速率提高，当臭氧投加量500mg O3·g-1SS时，去除率达到95%以上。耦合H2O2氧化过程，会产生协同效应从而提高去除效率，各PAH的协同增强值S分布在4.57到26.68之间。pH的提高会加速溶液中羟基自由基的生成从而提高多环芳烃的分解速率。多环芳烃在焦化污泥上的吸附性直接影响其臭氧氧化过程。整个氧化分解动力学过程符合拟一级动力学模型。强化传质过程有效提高臭氧流化床中O3氧化PAHs的O3利用效率。对焦化废水外排水中残余活性、毒性组分的系统分析，以消毒副产物前体物势能作为评价指标分析残余组分的环境行为，为研究焦化废水深度处理工艺提供了理论依据。以PAHs作为典型污染物，臭氧流化床反应器对焦化废水外排水和剩余污泥中的多环芳烃的氧化过程，为构建焦化废水深度处理的臭氧流化床成套装置提供发展方向。更多还原

【Abstract】 Coking wastewater is generated from coal coking, coal gas purification, andby-product recovery processes of coking. It contains lots of inorganic pollutants andorganic pollutants, such as ammonium, sulfate, cyanide, thiocyanate, phenoliccompounds, polycyclic aromatic hydrocarbons (PAHs), nitrogen-, oxygen, andsulfur-containing heterocyclic compounds. Most of these compounds are refractory,toxic mutative, and carcinogenic, thus the pollution caused by coking wastewater is aserous problem in the world. Although the coking wastewater effluent meet thenational discharge standard after a multistage water treatment process, the TOCremains always about30mg·L-1. For the residual toxicity, active substance in cokingwastewater discharge, because of the limitation of environmental regulations andanalysis technique, it is a lack of comprehensive understanding of the environmentalbehavior of it. Therefore, the treatment of coking wastewater discharge is a challengetask in coking industry and a better understanding of the the composition of theindustrial wastewater and the behaviors and fate of specific compounds during thewastewater treatment will be helpful to optimize the system for controlling andminimizing the amount of PAHs discharged to environment.On the basis of the analysis of the conventional control indicators, the residualorganic compounds were adopted for separating by XAD-8, Dowex50and Amb-R900resin separation technology and ultrafiltration method. It is the first time to use thedisinifection by-products formation potential to evaluate the environmental risk oftoxicants in coking wastewater discharge. The high risk of disinfection by-productsprecursors was screen by coupling the solid phase extraction enrichment method withsilica-alumina extraction technology and GC-MS analysis. Results showed thatorganic matter>100kDa and <1kDa parts have a higher trihalomethanes (THMs) andhalogen acetonitrile (HANs) formation potential. The hydrophilic acidic organicmatters in coking wastewater have the highest proportion. According to the threedimensional flurescence spectrum and GC-MS analysis, microbial metabolitesexhibited high fluorescence response though not high in concentration. Among <1kDaarganic matter, about120kinds of disinfection by-product precursors were indentified, including nitrile, amine, nitrogen heterocyclic nitrogen, phenols, hydrocarbons, esters,acids, alcohols, polycyclic aromatic hydrocarbons and oxygen heterocyclic organiccompounds.Ozonation significantly reduced the amount of precursors of DBPs in cokingwastewater effluent. Furthermore, it was found that higher concentration of O3resulted in lower amounts of precursors. The results of DOC, UV254and SUVAshowed that O3preferentially decomposed DOM that had unsaturated and aromaticcomponents. The results of MW and3DEEM showed that small MW (<1kDa) DOMwas more easily degraded by O3as compared to large MW (>1kDa) DOM. Thespecies of organic compounds in effluent have been changed by ozonation.Nitrogenous orginc compounds such as nitrogen-containing heterocylic compoundsand nitrile can be oxidated fastly. Amine presented a trend that increased at thebeginning and than decreased. Olefin and phenol which contain unsaturatedfunctional groups can be also oxidated selectively by ozonation. On the other hand,organic acids and alkane have been formed in the process of ozonation. But theseintermediate compounds showed relatively low formation potential of HAN and THM.Therefore, precursors of HAN and THM can be mineralization or be converted toorganic compounds which have lower disinfection byproducts formation potential. Allthe results provided evidence that treatment of coking wastewater effluent byozonation was effective in minimizing the disinfection byproducts formation potential(DBPFP). Ozonation can reduce the environmental risk of the effluent of cokingwastewater treatment plants, and improve the security of water supply.Coking wastewater treatment plant (CWWTP) represents a point source ofpolycyclic aromatic hydrocarbons (PAHs) to environment. A pilot-scale O3/ultraviolet(UV) fluidized bed reactor (O3/UV FBR) was designed to enhance the removal ofresidual PAHs. Different operation factors including UV irradiation intensity, pH,initial concentration, contact time, and hydraulic retention times (HRTs) wereinvestigated at an ozone level of240g·h-1and25±3℃. The health risk evaluationand cost analysis were studied under the continuous-flow mode. Results indicated that18target PAHs were effectively removed in O3/UV FBR due to synergistic effects.Either increased reaction time or increased pH was beneficial for the removal of PAHs.The degradation of the target PAHs within8h can be well fitted by the pseudo first-order kinetics (R2>0.920). The reaction rate was also positively correlated withthe initial concentration of PAH. The health risk assessment showed that the totalamount of carcinogenic substance exposure to surface water was reduced by0.432g·d-1. The economic analysis showed that the O3/UV FBR was able to remove18target PAHs at a cost of0.16USD per cubic meter. These results suggest that O3/UVFBR is efficient in removing residuals from WWTP, thus reducing the accumulationof persistent pollutant in surface water.Activated coking wastewater sludge is a significant problem, due to thehydrophobic organic micro-pollutants which are adsorbed on it. This work discussesan O3fluidized bed reactor (FBR) process to stabilize and reduce coking sludge andremove16target polycyclic aromatic hydrocarbons (PAHs) adsorbed onto the sludgeduring this process. The degradation efficiencies and influential factors affectingsludge ozonation were investigated. The results indicated that the target PAHs presentin activated coking sludge can be effectively removed by O3, especially the highmolecular weight PAHs. However, the dose of O3that is applied should be carefullycontrolled, because a low dose (e.g.,300mg O3g-1SS) can lead to an increase in theconcentrations of PAHs in the liquid phase of activated coking sludge. Furthermore,the addition of H2O2or an increase in pH can improve the removal of most of thetarget PAHs, because of a synergistic effect (S>0). The degradation kinetics of thetarget PAHs were assigned to a pseudo first-order model. By this process it becamepossible to reduce the amount of activated coking sludge, as well as achieve removalof PAHs adsorbed on it, with a minimal O3dosage.The results from this study enrich the knowledge of coking wastewater discharge,which promises to be useful for the research of advanced treatment technology. Theidentification of DBPFP can be applied as an index for the environment behaviors ofcoking wastewater discharge. The assessment of removal of residual PAHs in thedischarge and sludge of coking wastewater by O3fluidized bed reactor provideprospectives for advanced treatment of WWTP.更多还原