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题名: 内置电极载体的复合型厌氧工艺效能及电极材料优化
作者: 崔 丹1
学位类别: 博士后
答辩日期: 2017-07
授予单位: 中国科学院大学
授予地点: 北京
导师: 庄绪亮 ; 王爱杰
关键词: 复合型厌氧 ; 电极载体 ; 偶氮染料 ; 流态 ; 石墨烯 ; Hybrid anaerobic process, electrode module, azo dye, hydrodynamics,graphene
其他题名: Performance and electrode material optimization of hybrid anaerobic process built-in with electrode carrier
学位专业: 环境科学与工程
中文摘要: 厌氧生物法以其成本低、效率高和环境友好性的特点,在废水处理中占有举 足轻重和不可替代的地位,但厌氧生物工艺处理速度慢的弊端一直是限制其应用 的关键所在。为了加速厌氧生物反应并强化厌氧工艺的效能,在传统的厌氧工艺 中引入生物电化学系统( BESs),构建内置电极载体的复合型厌氧工艺装置 (HAR),通过定向的电位调控和电极微生物催化作用,可以实现梯级强化水中 难降解污染物厌氧去除的目的。本研究围绕“内置电极载体的复合型厌氧工艺装 置”规模化应用过程中的关键问题:工艺构型、流态特征和电极材料优化,开发 了新型复合型厌氧工艺,并对其效能、微生物群落分布及流态特征进行分析,深 入理解和评价电极载体的作用;并建立了石墨烯修饰碳纤维电极的方法,以期减 小电极载体的阻抗,解决电极模块放大后电压降大和能耗损失大的问题。 首先,为了考察放大规模的复合型厌氧工艺的效能,并获得有效可行的模块 构型,本研究构建了 30L 规模的内置套筒型电极载体的复合型厌氧装置 HAR, 用其处理含偶氮染料废水,HAR 对废水的处理效能表现出快速高效的特点,相 比传统厌氧工艺 AR,HAR的启动速度更快,当 HRT缩短到 4h,进水染料负荷 为 800g AYR/ m3•d时,对偶氮染料的去除效率依然高达 93.8±6.7%,比 AR提高了 10%,电极载体对偶氮染料的去除起到了强化作用。 其次,为了探究电极载体和电场引入后,装置中的微生物群落结构特征,采 用 16S rRNA方法对 HAR中不同位置的微生物群落进行分析,结果表明电极载 体的引入和套筒型的设计,使装置中不同位置的微生物群落结构产生明显差异, 污泥区以发酵菌为主,包括 Desulfobulbus 和 Kosmotoga,它们与水解酸化过程 直接相关,使水中有机物水解酸化为小分子酸;电极载体区以电活性微生物为主, 包括 Syntrophus 和 Geobacter,它们具有电子传递功能,并兼具偶氮及硝基还原 作用,这证明了在电极载体区可以有效发生偶氮染料的转化过程;同时,电极载 体的存在,也使系统内的氢分压增大,利于嗜氢产甲烷菌的富集,促进了挥发酸 的转化,使 COD的去除率提高。 再次,为了考察电极模块对装置水力流态的影响,通过水力停留时间分布实 验(RTD)和计算流体力学模拟(CFD)考察复合型厌氧工艺 HAR的流态特征, 结果表明电极载体填充反应装置上部空间,起到了再次布水的作用,电极载体的 存在有效改善了装置流态,减少了短流、沟流、拖尾等现象,延长了实际水力停 留时间,并使污泥体积分数提高,促进了传质,装置流态更趋近平推流,符合扩 散模型。 最后,为了减小电极材料的阻抗并降低电极成本,对碳纤维电极进行改性, 建立了一步电沉积石墨烯修饰碳纤维的方法,可以快速有效的将氧化石墨烯还原 为石墨烯,并同步将石墨烯修饰在碳纤维电极表面,构建 rGO/碳刷电极。相比 于传统碳纤维刷电极, rGO/碳刷电极的电化学活性大大提高,电荷传递阻力由 325.5 Ω减小到 63.07 Ω,电极表现出双电层电容效应,电活性面积增大了 3倍。 将其用于生物电化学系统 BES 中作为阴极,使装置的启动速度加快了 4 倍,缩 短为 48h,峰值电流由 0.2mA提高到 0.6mA,对偶氮染料的去除效率在 6h即可 达到 97%以上,并对偶氮染料的去除速率提高了 50%。同时,rGO/碳刷电极的 引入,使双极室生物电化学装置的阴极室部分阻抗显著减小,进而使装置的能耗 损失减小,大大降低了工艺成本。
英文摘要: Anaerobic bioprocesses take important and irreplaceable role in wastewater treatment due to the advantages of low cost, high efficiency and environmental friendly. However, the slow rate of anaerobic reaction as a key limited factor hinders the application of anaerobic processes. To accelerate and enhance anaerobic process, we introduced electrode modules into traditional anaerobic system to form a hybrid anaerobic reactor (HAR). Pollutants could be enhanced removal via potential control and biocatalysis. This research focuses on two key points that related to the application of HAR: effects of electrode configuration on performance and hydrodynamics, and optimization of electrode material for impendance redcuce. Thus, a newly hybrid anaerobic process was developed and was comprehensive studied from the aspects of performance, microbial community structure and hydrodynamics. The function of electrode modules was also well understood and evaluated. Moreover, to decrease the electrode resistance and energy loss, a method using graphene fabricating carbon brush was established. Firstly, we developed a hybrid anaerobic reactor built-in with sleeve type electrode modules (HAR, 30L). It showed fast and high efficiency for azo dye containing wastewater treatment. Comparing with traditional anaerobic reactor (AR), HAR started-up much faster. During stable continuouse operation, the azo dye decolorization efficiency of HAR was as high as 93.8±6.7% at HRT of 4h with azo dye loading rate of 800g AYR/ m3•d, which was 10% higher than that of AR. It proved that the electrode modules could enhance azo dye removal. Secondly, the introduction of electrode modules and sleeve type design stimulated the divergence of microbial community in HARS. In the sludge phase, fermention related bacteria including Desulfobulbus and Kosmotoga were enriched, which were functional for hydrolysis and acidification. In the electrode zone, electroactive bacteria including Syntrophus and Geobacter were dominant. They were related to electron transfer and nitro or azo-bound reduction. This supported that azo dye could degrade at the electrode zone. Besides, the electrode modules led to H2 evolution, which was favorable for the enrichment of hydrogenophic methanogens. Thus, volatile fat acids (VFAs) as well as COD removal could be improved. Thirdly, the hydrodynamics of HAR were investigated using retention time distribution (RTD) and computational fluid dynamics (CFD). The results indicated that the electrode modules that filling the upper space of HAR could distribute water again. The inferior characteristics of hydrodynamics, such as short flow, channeling and tailing, were avoided. The actual retention time was extended, the sludge volume fraction was increased and the mass transfer was improved. The flow pattern of HAR was much close to plug flow, which could be simulated by disperse flow model (DFM). Finally, we developed a method via one-step electrodeposition graphene for carbon fiber fabrication. Graphene oxide could be fast and efficient reduced to graphene and fabricated on the surface of carbon brush simultaneously (rGO/carbon brush). The electrochemical activity of rGO/carbon brush was greatly improved comparing with that of unmodified one. The electron transfer resistance decreased from 325.5 Ω to 63.07 Ω and the electrochemical surface area (ECSA) was 3 times higher. Using the rGO/carbon brush as cathode in BES for azo dye removal, the start-up time of BES was shortened to 48h, which was 4 times faster. The peak current increased from 0.2 to 0.6mA. The azo dye removal efficiency was as high as 97% at 6h with 50% faster azo dye removal rate. The rGO/carbon brush cathode reduced the impendance of BES significantly, thereby decreased the energy loss and cost.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38610
Appears in Collections:中科院环境生物技术重点实验室_学位论文

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Recommended Citation:
崔 丹. 内置电极载体的复合型厌氧工艺效能及电极材料优化[D]. 北京. 中国科学院大学. 2017.
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