基于电势调控的生物电极与厌氧工艺耦合系统强化氯代硝基苯还原转化研究

发布时间：2018-01-14 15:30

  本文关键词：基于电势调控的生物电极与厌氧工艺耦合系统强化氯代硝基苯还原转化研究　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 2 4-二氯硝基苯 生物阴极 上流式厌氧生物反应器 阴极电势 还原脱氯

【摘要】：氯代硝基苯类化合物(ClNBs)是化工、医药、染料等行业重要基础原料,具有三致效应与遗传毒性、化学性质稳定、生物降解性差等特点,在生产与使用过程中因不合理处置导致大量进入环境,威胁生态安全与人类健康。目前,含ClNBs废水处理多以厌氧工艺为主,存在启动周期长、电子供体不足、还原性能待提升等问题。论文以2,4-二氯硝基苯(2,4-DClNB)为研究对象,构建了耦合生物电化学(BES)的厌氧生物处理装置,从阴极电势、电子供体、电极位置等方面开展生物电化学-厌氧污泥耦合工艺性能强化研究,通过目标污染物降解途径、污泥菌群结构分析初步揭示基于电势调控的生物电极与厌氧微生物耦合工艺的作用机制,取得如下研究成果:1、构建了双极室生物电化学装置,在外加电压0.6V、阴极室无电子供体,阳极室含有500mg/LCOD,目标污染物2,4-DClNB浓度为50mg/L的条件下,反应24 h后,2,4-DClNB在阴极室完全还原转化。而在开路对照实验装置中,2,4-DClNB还原转化停滞,证实阴极微生物可利用阴极作为唯一电子供体还原转化2,4-DClNB。构建多组生物电极-厌氧污泥耦合的单极室生物电化学装置研究生物电极与厌氧污泥协同还原转化2,4-DClNB过程发现,在初始COD浓度500mg/L,2,4-DClNB浓度50mg/L,污泥浓度3g/L的条件下,120h时,单独厌氧污泥反应器中4-氯苯胺(4-ClAn)的降解速率为2.24mg/L·d,而阴极电势为-450mV、-660mV、-870mV的耦合反应器中,4-ClAn的降解速率分别为3.51 mg·L~(-1)·d~(-1)、4.61 mg·L~(-1)·d~(-1)和4.84mg·L~(-1)·d~(-1),明显高于对照反应器,表明生物电极-厌氧污泥耦合体系可明显加快反应限速步骤4-ClAn的脱氯过程,且较低的阴极电势有更利于C-Cl键断裂,促进4-ClAn的还原脱氯。2、构建了MEC-UASB耦合反应器,研究阴极电势对耦合工艺处理2,4-DClNBs的影响。结果表明,在进水COD和2,4-DClNB负荷分别500 g·m~(-3)·d~(-1)和50g·m~(-3)·d~(-1)、水力停留时间24 h条件下,阴极电势为-660mV的耦合反应器中,4-ClAn的去除速率与苯胺(An)的生成速率分别为19.56±0.84mg·L~(-1)·d~(-1)和4.12±1.33mg·L~(-1)·d~(-1),高于阴极电势-450mV的耦合反应器的17.38±0.97mg·L~(-1)·d~(-1)和2.97±1.21mg·L~(-1)·d~(-1)。分析认为,阴极电势是驱动阴极生物化学反应的本征电化学参数,较低的阴极电势能够为脱氯微生物提供更多的能量用于脱氯反应,并通过析氢反应产生有效电子供体H2,强化氯代硝基苯还原脱氯。对反应器内电极空间布设影响研究发现,将电极位置由反应器底部抬升10cm至反应器中部,限速反应步骤4-ClAn的去除速率增至20.92±0.82mg·L~(-1)·d~(-1)。推测抬升电极位置可强化目标污染物中间产物在升流式反应器中上部进一步还原脱氯。此外,进水有机负荷由500gCOD·m~(-3)·d~(-1)降至200gCOD·m~(-3)·d~(-1)时,2,4-DClNB进水负荷仍保持50g·m~(-3)·d~(-1)时,耦合反应器的脱氯率为56.41±3.51%,高于传统UASB的43.25±2.88%,表明耦合工艺能够将有限的电子更高效地用于2,4-DClNB还原转化。3、对耦合工艺生物阴极显微观察发现,生物阴极表面附着具有鞭毛状结构的球菌、杆菌、丝状菌等微生物;生物阴极生物膜荧光染色技术分析活细胞主要存在于阴极生物膜表层与中间层,而内层多为死细胞,推测可能存在类似纳米导线的长距离电子传递机制。应用Illumina高通量测序技术分析颗粒污泥菌群结构发现,耦合工艺运行过程污泥微生物菌群结构演替显著,在属水平上,耦合工艺中的Methanoregula、Methanolinea、Pseudomonas、Desulfovibrio、Longilinea、Dehalococcoides、Dehalobacter和Anaeromyxobacter的相对丰度显著增加,表明耦合系统中产甲烷微生物、厌氧发酵菌、脱氯微生物得到明显富集。进一步分析生物阴极表面生物膜微生物菌群结构发现,生物阴极作为催化还原反应的活性界面,定向富集了Dehalobacter、Dehalococcoides和Anaeromyxobacter等多种脱氯菌属,是耦合工艺强化还原脱氯的内在原因。相比,阴极电势为-660mV的生物阴极上,脱氯功能菌Dehalococcoides(5.2%)、Anaeromyxobacter(2.9%)和Dehalobacter(3.0%)占比较高,推测这些功能菌在电势较低的阴极上能够获得更多的能量用于还原脱氯与自身生长。
[Abstract]:Chloronitrobenzenes compound (ClNBs) is a chemical, pharmaceutical industry, dyes and other important raw materials, with three induced effects and genetic toxicity, stable chemical properties, poor biodegradation characteristics in the production and use of the process because of the unreasonable disposition lead into environment, threatening the ecological safety and human health. At present, including ClNBs wastewater treatment by anaerobic process, starting a long cycle, the electron donor shortage reduction performance to be improved and so on. This paper use 2,4- two 4-chloronitrobenzene (2,4-DClNB) as the research object, construct a coupled biological electrochemical (BES) anaerobic biological treatment device, from the cathode potential, electron donor, electrode position etc. study on strengthening the technological performance of anaerobic sludge bio electrochemical coupling, through the target pollutant degradation pathway, preliminary analysis reveals the biological regulation of the electrode potential and anaerobic microorganisms based on sludge microflora The mechanism coupling process, the main achievements were as follows: 1, construct the double chamber bioelectrochemical device with voltage 0.6V, the cathode chamber of electron donor, the anode chamber containing 500mg/LCOD, 2,4-DClNB concentration of the target pollutants under the condition of 50mg/L, after 24 h reaction, 2,4-DClNB reductive transformation completely in the cathode chamber. In open circuit control the experimental setup, the 2,4-DClNB reduction can be used as the cathode microbial stagnation, confirmed only electron donor reduction chamber bioelectrochemical transformation construction of 2,4-DClNB. monopole multi biological electrode coupling device of anaerobic sludge and anaerobic sludge bio electrode process by 2,4-DClNB synergistic reductive transformation of cathode at the initial COD concentration 500mg/L, 2,4-DClNB concentration 50mg/L, sludge concentration 3g/L under the condition of 120h, 4- chloro aniline single anaerobic sludge reactor (4-ClAn) degradation rate of 2.24mg/ L D, while the cathode potential is -4 50mV,-660mV,-870mV鐨勮，

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