【作者】 刘鼎；

【导师】 雷乐成；

【作者基本信息】 浙江大学 ， 环境科学， 2014， 博士

【摘要】 针对难降解有机废水B/C(生化需氧量／化学需氧量)低、生物毒性强,传统生化法处理效果差的问题,本论文提出采用微生物电化学系统(BES)中的生物阴极处理该类有机废水,以解决传统生化处理工艺的不足。论文取得了如下主要研究成果：以活性蓝13(RB13)和五氯苯酚(PCP)为典型难降解有机污染物,建立了一套适用于难降解有机污染物处理的电化学活性细菌(EAB)筛选与驯化方法,分别获得了高效降解RB13和PCP的EAB。利用该两种EAB启动BES,生物阴极挂膜时间大大缩短。在此基础上,考查了生物阴极对RB13和PCP的处理效果,结果显示：在优化条件下,RB13经8h处理后,脱色率达到80.24±5.51%；PCP经100h处理后,去除率达到89.66±3.66%。重点研究了生物阴极上EAB生物膜与电极之间的电子传递机制。结果发现生物阴极中电极到EAB存在直接电子传递途径。循环伏安法测试发现生物阴极表面生物膜在+0.2V左右有氧化还原峰,对应于细菌细胞膜上的C型细胞色素蛋白,为直接电子传递途径的存在提供了有力的证据。对EAB生物膜菌落组成进行了分析,454高通量测序结果显示Proteobacteria (45.51%)、Bacteroidetes (33.95%)、Firmicutes (15.92%)为脱氯生物阴极上三类优势菌种。对EAB生物膜在电极表面的形成过程及其影响因素进行了研究。论文建立了一套基于微电极的EAB生物膜厚度原位连续测试的方法。以Shewanella oneidensis MR-1为模型微生物,通过铂探针微电极对S. oneidensis MR-1生物膜厚度进行了测试,测试结果与激光共聚焦扫描显微镜测试结果基本吻合。利用该方法对S. oneidensis MR-1生物膜形成过程中的影响因子进行考查,发现较负的电极电势以及较高浓度的乳酸钠、核黄素可加速S. oneidensis MR-1生物膜的生长。无氧条件下,S. oneidensis MR-1生物膜厚度增长的限值大约为100μm到110μm。利用Capdeville生物膜增长动力学模型对观察到的生物膜生长过程进行数学模拟。拟合结果显示当乳酸钠浓度为20mM,电极电势为+100mV时,Soneidensis MR-1生物膜厚度的比增长速率为0.27h-1。构建了基于生物阴极的微生物燃料电池堆栈,为生物阴极在难降解有机废水处理中的工程化应用提供了设计指导。当外接电阻1000Ω时,含50mg/L RB13的模拟废水经反应器处理8h后,RB13脱色率和TOC去除率分别为85.4±2.4%和33.44-3.4%。本论文以难降解有机废水生物处理新工艺开发为目标,系统整合了BES和生物阴极,阐明了污染物降解过程中的电子传递机制,揭示了生物膜形成的机制和调控手段,拓宽了BES在废水处理中的应用范围。更多还原

【Abstract】 More and more recalcitrant organic wastewater was generated with the rapid development of chemical industry recently. Due to the low B/C, poor biodegradability and high toxicity, traditional bioremediation cannot effectively treat this kind of wastewater. A bioelectrochemical system (BES) equipped with biocathode was employed for recalcitrant organic wastewater treatment in this work.Reactive blue13(RB13) and pentachlorophenol (PCP) were treated as typical recalcitrant organic pollutants in this paper. Firstly, a novel method for screening and acclimating electrochemically active bacteria (EAB) for the degradation of recalcitrant organic pollutions was provided. EAB for RB13degradation and EAB for PCP degradation were obtained, which can significantly reduce the time of biocathode set-up. Biocathodes used for RB13and PCP treatment were also built, and the performance of biocathodes for RB13degradation and PCP degradation were significantly improved. In the optimized conditions, the decolorination rate of RB13in BES reached80.2±5.5%during8hours operation, and the PCP removal rate in BES reached89.7±3.7%after100hours treatment.For understanding the degradation pathways of recalcitrant organic pollutants on biocathode, the electron transfer mechanisms of EAB on biocathode were studied. The electron transfer pathway from electrode to EAB was determined. We proved that direct electron transfer mechanism from the electrode to EAB could be involved in biocathode. A pair of oxidation-reduction peaks around+0.2V existed in the cyclic voltammograms, which could be caused by cytochrome C protein.454pyrosequencing tests showed that Proteobacteria, Bacteroidetes and Firmicutes were three predominant phyla in BES, which were three dechlorinating microorganisms.Given the importance of EAB biofilm in biocathode, EAB formation mechanisms were studied. A novel method for in situ determination of the EAB biofilm thickness was developed. By employing a platinum ultramicroelectrode (Pt UME) as the detector, thickness of Shewanella oneidensis MR-1biofilm was measured, and the results were also confirmed by confocal laser scanning microscope tests. According to our results, lower electrode potential, higher concentrations of sodium lactate and riboflavin could accelerate the formation of S. oneidensis MR-1biofilm on the electrode. The maximum biofilm thickness was100μm to110μm when S. oneidensis MR-1grown in the anaerobic medium. Capdeville equation was found describing the formation of EAB biofilm well. When the concentration of sodium lactate was20mM and the electrode potential was+100mV, the specific growth rate of S. oneidensis MR-1biofilm thickness was0.27h-1.A bipolar microbial fuel cell stack equipped with biocathode was constructed. It provided a guideline for the designation of the large scale reactor for recalcitrant organic wastewater treatment. When the external resistance was1000Ω and the initial RB13concentration was50mg/L, the RB13removal rate and the total organic carbon (TOC) removal rate in this reactor were85.4±2.4%and33.4±3.4%respectively during8hours operation.This work focused on the development of a novel technology for recalcitrant organic wastewater treatment. By employing biocathode in a BES, recalcitrant organic pollutants were degraded effectively. Furthermore, the electron transfer mechanisms during the progress of pollutants degradation and the formation mechanisms of EAB biofilm were determined. This work extended the application of BES in wastewater treatment.更多还原