【作者】 韩涛；

【导师】 韦朝海；

【作者基本信息】 华南理工大学 ， 环境工程， 2015， 硕士

【摘要】 焦化废水尾水通常指经过生物处理和混凝处理后排放的废水,其中仍残留一些难生物降解的有机物及少量无机物,这不仅对接受水体环境造成污染,同时也给水回用带来技术上的难度。新国标中提出的COD 80 mg/L的排放要求更使得尾水深度处理势在必行。对焦化废水尾水中污染物浓度削减过程的探索,可以为尾水深度处理工艺的优化设计提供指导和依据。本文首先研究了臭氧流化床反应器深度处理焦化废水尾水过程,考察臭氧投加量、pH、水力停留时间等对反应过程的影响。结果显示,间歇条件下焦化废水尾水的COD值随着臭氧投加量的增加而下降,当臭氧量超过430 g时COD值趋于稳定,投加的臭氧量与降解的COD之间的比值随反应时间延长不断增大。pH对焦化废水尾水的臭氧氧化过程影响不大,碱性条件下尾水COD、UV254和色度的去除率分别为51.5%、87.3%和85.0%,略优于中性和酸性条件。连续条件下焦化废水尾水的COD值随停留时间的延长而降低,停留时间为2h时COD<40mg/L。在0-30 min和45～120 min两个阶段,COD和色度随时间降解曲线均服从拟一级动力学反应方程。采用紫外-可见光、三维荧光和GC/MS这三种手段进一步分析了臭氧流化床深度处理焦化废水尾水过程中有机组分的变化。结果发现,焦化废水尾水中主要存在的有机物如烷烃类、含氮杂环类、醇类、酸类、酯类以及少量的醚类和多环芳烃等,经过臭氧氧化反应后,转化为一些新的有机物,如烷烃、苯甲醇、己酸等物质,分子量变小。其中,具有荧光响应的物质能够被有效分解,分解率的顺序为类色氨酸物质>类溶解性微生物副产物>类腐植酸物质>类酪氨酸物质。焦化废水尾水与各个氧化阶段的水样在200～250nm范围内都具有较强的紫外吸收,且其紫外吸收强度随反应时间的延长不断减弱。尾水中16种PAHs的总量约为3.518μg/L,经过2 h臭氧氧化反应后,去除率达到51.1%。其中,环数≥5的PAHs平均去除率达到70.3%,高于低环PAHs的去除效果。针对臭氧深度处理过程的残余臭氧,本文又进一步尝试了臭氧深度处理焦化废水尾水的同时,利用臭氧尾气原位制备聚合硫酸铁。研究结果显示臭氧氧化焦化废水尾水过程中,相比臭氧尾气的直接释放,硫酸亚铁溶液对臭氧尾气的吸收使得臭氧利用率提升到原来的3倍多。利用臭氧尾气合成的聚铁性能指标达到或超过了国标的要求(GB14591-2006)。聚铁的盐基度随硫酸投加量增大而减小,反应温度为50℃时其盐基度达到最大值。更多还原

【Abstract】 In the real coking wastewater treatment plant, the effluent after bio-treatment and coagulation still contains a particular proportion of biorefractory organics and inorganics. It will contaminate the water environment if discharged directly and induce technical difficulties in water reuse. The advanced treatment of coking wastewater effluent becomes imperative since the new national standard of COD emission of 80 mg/L is required. Exploring the reducing process of pollutants in coking wastewater effluent can provide guidance and basis for the optimal design of advanced treatment of coking wastewater effluent.This paper firstly studied the advanced treatment of coking wastewater effluent with ozone-fluidized bed reactor, the effect of ozone dosage, pH, hydraulic retention time (HRT) on the reaction process was analyzed. The results indicated that, the COD concentration of coking wastewater effluent decreased with the ozone dosage and tended to stable when the ozone dosage was more than 430 g under intermittent condition. The pH value had little influence on the ozonation of coking wastewater effluent, the removal efficiencies of COD> UV254 and color intensity in alkaline condition were 51.5%、87.3% and 85% respectively, slightly larger than those obtained in acidic and neutral conditions. The COD concentration of coking wastewater effluent decreased with HRT, and the COD value is below 40 mg/L with a HRT of 2 h. The COD and chromaticity degradation curves over time obeyed the pseudo first order reaction kinetics equation in 0-30 min and 45-120 min.The variation in organic composition was further analyzed by ultraviolet and visible spectrophotometer, three-dimensional fluorescence spectrometer and Gas Chromatography Mass Spectrometry (GC/MS). The results indicated that, Major organics in coking wastewater effluent included Alkanes, N-heterocyclic carbenes, Alcohols, Acids, Esters, and a small quantity of Ethers and polycyclic aromatic hydrocarbons (PAHs), etc. After ozonation, some of the non-biodegradable organics in effluent have been removed partially or completely, and have been turned into some new organics, such as, Alkane, Phenylcarbinol, Hexanoic acid, etc and the molecular weight decreased. The materials with fluorescence response can be effective decomposed, and the decomposition rate of order is tryptophan-like> soluble microbial products-like> humic acid-like> tyrosine-like. There existed strong ultraviolet absorption at 200～250 nm in coking wastewater effluent and ozonated effluent, and the intensity of ultraviolet absorption decreased with the reaction time. The concentration of 16 kinds of PAHs in wastewater effluent was about 3.518μg/L, after 2 h ozonation, the removal rate reached 51.1%. Among them, the removal rate of PAHs with ring number of 5 or more reached 70.3%, higher than the lower ring PAHs removal effect.Considering the residual ozone in advanced treatment with ozone, this paper further attempted the advanced treatment of coking wastewater effluent and produced polymeric ferric sulfate (PFS) with off-gas ozone at the same time. The results showed that, compared with the direct release of off-gas ozone, the utilization rate of ozone increased to more than 3 times by the absorption of off-gas ozone with ferrous sulfate solution. The performance indicators of PFS synthesized with off-gas ozone meet or exceed the requirements of national standard (GB 14591-2006). The basicity of PFS decreased with increasing sulfuric acid dosage, and it reached maximum when the reaction temperature was 50℃更多还原