【作者】 邓留杰；

【导师】 韦朝海；

【作者基本信息】 华南理工大学 ， 环境工程， 2014， 博士

【摘要】 焦化废水成分复杂，处理难度大，因其中含有氨氮和难降解有机物，对环境可造成严重的危害。氨氮浓度过高可直接导致鱼类等水生生物的死亡，氨氮氧化后产生的硝酸盐和亚硝酸盐也具有致癌作用。焦化废水中的难降解有机物主要有酚类化合物、多环芳香族化合物及含氮、氧、硫的杂环有机化合物等，其中烷基酚、邻苯二酸(酯)、吡啶等污染物属于环境内分泌干扰物，而多环芳烃等物质也被美国EPA认定为优先控制污染物。这类废水中氨氮和有毒、难降解有机物的产生和累积，导致针对此类废水的常规处理方法处理后难降解有机物仍有痕量存在，且处理所需的总水力停留时间长。电化学生物法处理有机废水和氨氮废水有很高的电流效率和很好的水处理效果，但技术尚且不成熟，有许多问题有待解决，如电极上生物挂膜问题，电子传递问题等。因此，开展电化学生物法处理焦化废水的实际研究具有重要意义和价值。本研究针对含有高浓度氨氮和难降解有机物的模拟焦化废水，首先构建AO生物流化床反应器并保持稳定运行，再采用优势菌富集培养和电化学诱导的强化方法，提高了废水中氮和有机污染物的去除效率。通过反应器中活性污泥的流态化和电解质的添加，该电化学生物流化床系统不需要进行生物挂膜，即可使电子在电极、微生物和污染物直接传递。通过对实际焦化废水处理站工程运行数据的检测分析发现，在生物处理的总水力停留时间为76h的情况下，焦化废水经生物三相流化床A/O1/H/O2组合工艺处理后，生物处理出水平均COD、酚和氨氮分别为145.5mg/l、0.10mg/l和0.53mg/l。GC-MS分析表明，焦化废水中的酚类、吡啶、喹啉等易降解有机物得到了高效去除，长链烷烃、多环芳烃、苯系物等难降解、有毒物质在处理后的出水中仍然存在。针对焦化废水处理所需时间长的问题，本研究首先构建了生物流化床处理系统，其试验中的稳定运行最佳条件为：无机碳氮比CO32--C/N=2:1，有机碳氮比CH2-C/N=1.5:1。氨氮进水浓度300mg/l以下时，其去除率维持在95%以上；而厌氧反应阶段硝酸盐氮的去除效率在进水氨氮浓度低于200mg/l时也可达到95%以上。在低温条件下，AO生物流化床处理系统对硝酸盐氮和有机物的去除不彻底，22℃时硝酸盐氮的去除速率仅为2.87mg/l/h，约80%的硝酸盐氮不能被去除。焦化废水处理后出水中含有多环芳烃等难降解有机物，因此驯化和培养高效降解此类有机物的功能菌株来强化焦化废水降解可以减少出水中有毒物质的含量，降低环境风险。以多环芳烃芘为代表，通过富集培养和高浓度驯化的方法，从焦化废水处理站的活性污泥中筛选分离出以芘为唯一碳源生长的特异降解微生物菌，分别命名为Pyr2、Pyr41和Pyr42，通过16S rDNA基因片段序列鉴定，Pyr2，Pyr41和Pyr42分别可能属于Castellaniella菌属，Pseudomonas菌属和Burkholderia菌属。Pyr2的最佳生长环境是pH6.5，温度32℃和摇床转速为70rpm，在最佳条件下12d内可将100.39mg/l芘降解97.2%。Pyr2的芘降解过程与硝化和反硝化作用同步进行，其生物代谢过程中的C/N约为1.776。Pyr4（包括两个菌株Pyr41和Pyr42）的最佳生长环境是pH7.0，温度35℃和摇床转速为100rpm，在最佳条件下48h内可将50.00mg/l芘降解65.02%，其生物降解过程符合一级动力学反应。根据动力学计算，Pyr4对芘的代谢速度可达到文献中所述速度的10倍左右。添加葡萄糖或蒽醌，对Pyr4芘生物降解的促进作用最明显，可使比降解速率从0.0337h-1增加到0.0689h-1或0.0721h-1。通过GC-MS的分析结果，Pyr2的生物降解过程中没有检测到中间产物，而在Pyr4生物降解过程中检测到1-萘酚的存在。将筛选并扩大培养的芘降解菌添加到运行中的生物流化床反应器中，并通过电化学方法强化生物降解来处理模拟焦化废水。研究发现，电流与生物反应具有协同作用，但10mA以上的电流对生物电化学反应速率的促进作用不明显。电流为10mA生物电化学作用下，当反应器进水氨氮负荷为200mg/l，COD负荷为650mg/l，运行温度为22℃，回流比为1:1.5，反应器总HRT为15h时，硝酸盐氮的去除速率可达到10.92mg/l/h，其去除速率为单纯生物反应器的3倍左右。废水中添加Cu2+作为电解质可促进生物电化学反硝化过程。单纯生物反应器处理过程中苯酚、喹啉和芘的去除率仅为63.1%、50.4%和56.2%，而生物电化学系统处理的有机污染物的去除速率都明显增大，苯酚、喹啉和芘的去除率都达到95%以上。通过PCR-DGGE分析，电化学诱导后在厌氧反应器中，有2个菌株含量明显增加，经进化树分析分别为Pseudomonas sp.和Rhodobacter sp.；在好氧反应器中，微生物群落的多态性却呈现减少的趋势，有3个菌株逐渐消失，经进化树分析，这些菌株分别为Bacillus sp.，Rhodococcus sp.和Sphingomonas sp.。由此得到结论：从活性污泥中筛选得到的Castellaniella Pyr2菌，对芘的降解过程与硝化反硝化作用相偶联。焦化废水中一般都同时含有氨氮和难降解有机物，如何同时降解氮和有机物是目前的难题，而Castellaniella Pyr2具备同时降解的能力，可为工业废水处理的科学研究乃至工程应用提供菌种来源。电化学生物流化床处理方法是首次将流化床结构应用于生物电化学法处理废水的工艺中，有效解决了生物电化学过程中的电子传递问题，避免了电极生物膜法工艺微生物挂膜困难且电极表面积小等限制因素。电化学生物流化床处理方法应用于模拟焦化废水处理过程中，可使得达标处理所需的水力停留时间缩短3倍以上，并可有效去除焦化废水中含有的难降解有机物，避免环境危害。更多还原

【Abstract】 Coking wastewater is with complex component and hard to be treated. Ammonia andrefractory organic compounds which included in coking wastewater may cause greatenvironment pollution. High concentration of free ammonia can directly affect fish and otheraquatic organisms even to die. In addition, nitrite and nitrate produced by ammonia oxidationhave carcinogenic effects. Refractory organic pollutants in coking wastewater containphenolic compounds, polycyclic aromatic hydrocarbons and nitrogen-, oxygen-, sulfur-heterocyclic organic compound. Within these pollutants, alkyl phenol, phthalic acid (ester),pyridine etc. are considered to be environmental endocrine disruptors, and polycyclicaromatic hydrocarbons are also identified as priority pollutants by the United States EPA.Generation and accumulation of these kinds of refractory organic pollutants in wastewater,may cause the conventional processing methods is difficult to reduce the risk.Bio-electrochemical method which applied to wastewater treatment has high electriccurrent efficiency and desired treatment effect. However, the technique, at present, isimmature and there are some key problems to be solved, for example, the difficult biofilmgrowing, and the low efficiency electron transference. So, bio-electrochemical method appliedto coking wastewater treatment is worth studying.This study aimed at treating of simulated coking wastewater containing highconcentration of ammonia and refractory organic compounds. Based on the AO biologicalfluidized bed reactor, strengthening methods, as organic degraders enrichment andelectrochemically inducing, are applied to improve nitrogen and organic pollutants removalefficiency in wastewater. By fluidized sludge and the electrolyte adding, thebio-electrochemical fluidized bed system can easily transfer electrons through electrode,microbial and the pollutants without bioflim growing.Based on the operation data of coking waste water treatment plant, the compersition ineffluent from biological fluidized bed A/O1/H/O2integrated process were COD145.5mg/l,phenolic compounds0.10mg/L, and ammonia0.53mg/l. By results of GC-MS, degradableorganic matter such as phenol, pyridine, quinoline, could be efficiently removed, whereasrefractory or toxic organic pollutants such as long-chain alkane, polycyclic aromatichydrocarbons, and benzene still remained in the effluent after treatment.Biological fluidized bed treatment system was constructed, and the optimal conditionswere: CO32--C/N=2:1, CH2-C/N=1.5:1. The removal rate of ammonia was up than95%wheninfluent ammonia concentration was under300mg/l; and the nitrate removal efficiency can also reach up to95%when influent ammonia concentration was less than200mg/l. Nitrateand organics can not thoroughly removed under low temperature. The nitrate removal rate isonly2.87mg/l/h under22℃, and80%of the nitrate remained in the effluent.As to treating the refractory organic pollutants in wastewater, polycyclic aromatichydrocarbons was studied as typical pollutants. By enrichment and domestication method,microbial grown with pyrene as sole carbon source were isolated from sludge of cokingwastewater treatment station and named Pyr2, Pyr41and Pyr42. By16S rDNA identification,Pyr2, Pyr41and Pyr42may belong to Castellaniella spp, Pseudomonas spp. andBurkholderia spp., respectively. Results showed that, optimal growth environment of Pyr2ispH6.5, temperature32℃and shaking speed is70rpm, and100.39mg/l pyrene can bedegraded by97.2%within12d under optimal conditions. Pyr2pyrene degradation processwas simultaneously accompanied with nitrification and denitrification, thus their biologicalmetabolism process of C/N is about1.776. Optimal growth environment of Pyr4(composedof two strains Pyr41and Pyr42) is pH7, temperature35℃and shaking speed is100rpm, and50mg/l pyrene can be degraded by65.02%within48h under optimal conditions. Pyr2pyrene biodegradation process is consistent with a first-order kinetic reaction. According tothe dynamics calculation, speed of Pyr4pyrene metabolism is about10times fastor than thereferrance.Pyr4pyrene biodegradation can be stimulated when glucose or anthraquinone added, andthe specific degradation rate increases from0.0337h-1to0.0689h-1or0.0721h-1. By theanalytical results of GC-MS, intermediate involved in Pyr2biodegradation process was notdetected, while1-naphthol was detected as one of the inermediates in the Pyr4biodegradation process.In the bio-electrochemical fluidized bed treatment process, there is a synergistic effectbetween electric and biological, but biological electrochemical reaction can not be obviousaccelerated when current supplied more than10mA. In the condition of the influent ammonia200mg/l, COD650mg/l, temperature22℃, reflux ratio1:1.5, HRT15h,10mA biologicalelectrochemical system could make nitrate removal rate reach up to10.92mg/l/h, which was3times higher than traditional bio-system. Adding of Cu2+could accelerate thisbio-electrochemical process. by contrast of phenol, quinoline and pyrene removal bytraditional bio-system was only63.1%,50.4%and56.2%, these removal bybio-electrochemical system could reach up to95%. By the PCR-DGGE analysis, in theanaerobic reactor after electrochemical inducing,2strains, Pseudomonas sp. and Rhodobacter sp. were obviously increased; in the aerobic reactor, microbial polymorphism had adecreasing trend, and there were3strains gradually disappeared, which were Bacillus sp.,Rhodococcus sp. and Sphingomonas sp..Nitrogen and refractory organic compounds are commonly exist in coking wastewater, sosimultaneous degradation of organic matter and nitrogen is the main problem of cokingwastewater treatment. Pyrene degradation process of Castellaniella Pyr2obtained from theactivated sludge was coupled with nitrification and denitrification. Thus, the specific strain ofCastellaniella Pyr2is worth scientific research and can be applied in industrial wastewatertreatment.The bio-electrochemical fluidized bed treating approach is the first time for fluidized bedreactor applied in bio-electrochemical reaction. Electron transfer and the limits of electrodemicrobial biofilm were effectively solved by the application of this approach. By using thebio-electrochemical fluidized bed approach to treat coking wastewater, the biologicalhydraulic remain time can be shortened for3times, and environment risk can also be deducedfor the efficient removal of refractory organic pollutants.更多还原