【作者】 崔丹；

【导师】 王爱杰；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2014， 博士

【摘要】 偶氮染料是染料中最大的化学分类，由于其廉价、稳定并且比自然染料颜色多样等特点，偶氮染料被广泛用于印染、造纸等工业生产中。但是，偶氮染料具有毒性大、难生物降解、色度高的特点，若直接排放到自然水体，不仅会造成视觉污染，其颜色还会阻碍光线和氧气的进入，严重影响水生生物的生存。我国是印染工业大国，印染废水日益增多，因此偶氮染料废水的脱色脱毒处理一直是我国工业废水处理的重点目标。近年来，生物催化电解系统已经发展成一种很有前景的水处理技术，它利用微生物在阳极催化氧化反应，驱动阴极电子受体的还原，从而将化学能转化为电能，其应用已经拓展到不同领域，例如生物产氢、有机物合成、金属还原、脱盐、以及多种废水处理等。围绕生物电化学系统的构型改进，以偶氮染料为处理目标，选取茜素黄R（AYR）为模式染料，开发了无隔膜的生物催化电解反应器，并将其与厌氧工艺耦合，在此基础上，构建了放大规模的厌氧折流板-生物催化电解一体式工艺（ABR-UBER）。为了解决传统双极室生物电化学系统成本高、难以放大的问题，设计了无隔膜的升流式生物催化电解反应器（UBER）用来强化偶氮染料的脱色。通过考察偶氮染料AYR对阳极电极微生物活性的影响，确定了当AYR浓度达到40mg/L时，阳极微生物失活，产电过程停止。因此，为了保护生物阳极的活性，UBER采用阴极在下，阳极在上的电极排布方式，阴极对生物阳极起到有效的保护作用，并采用无隔膜的结构，大大降低了工艺成本。在外加0.5V电压条件下，UBER对水中AYR（100mg/L）的脱色率达到94.8±1.5%，当水力停留时间（HRT）大于6h时，基于AYR在阴极区的去除量来计算的UBER的电子回收率接近100%，表明AYR的去除是阴极电化学还原的结果。当HRT小于2.5h时，AYR的脱色率降低，高浓度AYR废水流经阳极，使阳极微生物活性受到抑制，本研究中，UBER能够承受的最大进水AYR负荷为680g/m3·d（HRT：2.5h）。以阴极体积为研究对象，通过固定阳极大小，改变阴极体积的方式来考察阴极对UBER效能的影响。偶氮染料AYR在UBER中的脱色率、去除速率和电流密度随着阴极体积的放大而提高，但提高倍数远远小于阴极的放大倍数，说明放大的阴极无法被有效利用，但阴极体积较小时，反应器不稳定，能够处理的染料负荷较低。当阴极体积与阳极体积比例为2:1时，UBER的内阻最小（电荷传递阻力为39.5Ω），反应器效能最好。利用生物接触氧化反应器（ABOR）处理UBER的出水，AYR的还原脱色产物对苯二胺（PPD）和5-氨基水杨酸（5-ASA）在ABOR中被有效去除，当UBER-ABOR联合工艺的HRT缩短到6h时，末端出水的脱色率和COD去除率分别达到93.8±0.7%和93.0±0.5%，色度为80倍，满足我国染料废水排放的II级标准，最后分析了AYR在联合工艺中的转化代谢途径。基于UBER的设计，开发了厌氧-生物催化电解耦合工艺（AD-UBER），在UBER的下部引入厌氧污泥床，利用厌氧生物过程和生物电催化过程的优势，协同去除偶氮染料，脱色率达到90%以上，通过比较UBER、AD和AD-UBER对AYR的去除效果，分析了AD-UBER耦合系统去除偶氮染料AYR的过程原理，并得到当电极体系置于水相中时，更利于反应器效能的发挥。在AD-UBER的基础上，将多个AD-UBER组合放大，开发了厌氧折流板-生物催化电解一体式工艺（ABR-UBER），将UBER置于厌氧折流板反应器的每个格室中，生物电催化过程的引入，强化了偶氮染料的脱色，外加0.5V电压时，出水脱色率由开路的86.9±6.3%提高到95.1±1.5%，同时，乙酸的积累量减小，脱色率和电流密度随着UBER外加电压的提高（0.3、0.5、0.7V）而提高，分别达到96.4±1.8%和24.1A/m3·TCV（0.7V）。缩短HRT使ABR-UBER的脱色率降低，但各格室对AYR的去除速率随着HRT的缩短而提高，这表明ABR-UBER每个格室都具有较大的处理负荷，前面格室的处理能力是反应器整体性能的限制因素，后续格室在HRT较短时（4h）仍表现出较高的处理效能。ABR-UBER这种放大的无隔膜设计为生物电化学系统高效经济地去除偶氮染料及工艺放大应用提出了新的概念。更多还原

【Abstract】 Azo dyes are the largest chemical class of dyes and are frequently used for textile dying and paper printing industries due to cheap costs, firmness, and a variety of colors compared to natural dyes. However, azo dyes are highly toxic and persistent to biodegradation. Besides, the intensive color of dye-containing wastewater leads to severe aesthetic problems and obstructs light penetration and oxygen transfer into water bodies, adversely affecting aquatic life. For these reasons, the color removal from dye-containing wastewater is one of major concerns in China where textile industry has grown exponentially in recent years. Azo dyes should be removed from wastewater before being discharged to water body. More recently, Bioelectrochemical system (BES) is emerging as a promising technology in which microorganisms function as catalysts to convert chemical energy into electrical energy. BES has been tested for many potential applications besides electricity generation, including biohydrogen prodution, metal reduction and recovery, desalination, organic products synthesis and treatment of various wastewaters.This study focused on the configuration improvement of BES. Aliarin Yellow R (AYR) was selected as a model azo dye and was removed from wastewater using BES. A novel up-flow biocatalyzed electrolysis reactor (UBER) was developed. Then, anaerobic process was coupled with UBER to establish a process named AD-UBER. Basing on this, a small pilot scale anaerobic baffled reactor coupled with UBER (ABR-UBER) was developed.Firstly, we developed an economical BES lacking membrane (an up-flow biocatalyzed electrolysis reactor (UBER) for azo dye removal. This design avoided the problems of traditional bioelectrochemical reactor, such as high cost and difficult scaling-up. The toxic inhibition of azo dye (AYR) to the bioelectrochemical microoganisms was tested in a dual-chamber biocatalyzed electrolysis reactor to identify that AYR was highly toxic to the anodic bacteria. Anodic bacteria lost activity when AYR concentration reached40mg/L in the culture and current generation stopped. Thus, the cathode of UBER was placed at the bottom of the reactor to well protect the bioanode that set above the cathode. The elimination of membrane decreased the cost greatly. With the supply of external power source0.5V in the UBER, AYR decolorization efficiency reached up to94.8±1.5%. Electron recovery efficiency based on AYR removal in cathode zone was nearly100%at HRT longer than6h. Relatively high concentration of AYR accumulated at higher AYR loading rates (>780g/m3·d) likely inhibited acetate oxidation of anode-respiring bacteria on the anode, which decreased current density in the UBER; optimal AYR loading rate for the UBER was680g/m3·d (HRT2.5h).To optimize the performance of UBER, the effect of cathde volume, which was a key parameter of UBER, was investigated at a constant andoe volume. Decolorization efficiency was improved with increasing cathode size in UBERs, but AYR removal rate and current density did not increase in proportion to cathode size indicating that bigger cathode was more efficient for azo dye removal while most of the cathode could not be utilized effectively. However, smaller cathode volume was disbenefit to the stable operation of UBER. The best performance of UBER was obtaind when the volume ratio of cathode to anode was2:1where the charge transfer resistance Rct (39.5Ω) was minimal. AYR and its reductive products were further mineralized in the subsequent aerobic bio-contact oxidation reactor (ABOR). Decolorization efficiency and COD removal efficiency was93.8±0.7%and93.0±0.5%in the combined process of UBER and ABOR in overall HRT6h (HRT2.5h in UBER+HRT3.5h in ABOR). The Chroma in ABOR effluent was80times, which was satisfied with the texile wastewater discharge standard II. A possible AYR tranfermaion pathway was aproposed.Based on the design of UBER, we developed an anaerobic digestion-up-flow biocatalyzed electrolysis reactor (AD-UBER). A sludge bed was set below the UBER. Bioelectrochemical reaction was cooperated with anaerobic biological reaction for azo dye removal and the decolorization efficiency was higher than90%. The mechanism of AD-UBER was analyzed by comparing with the process of UBER and AD. The best performance of AD-UBER was obtained when the eletrodes were placed in the aqueous phase.Finally, we intended to combined several AD-UBERs together and enlarge the reacor. Therefore, a small pilot scale system that integrated UBER with ABR by installing UBER module into each compartment of ABR (called, ABR-UBER) was established for azo dye wastewater treatment. The ABR-UBER was operated without and with external power supply to examine AYR reduction process and reductive intermediates with different external voltages (0.3,0.5and0.7V) and hydraulic retention times (HRT:8,6and4h). The decolorization efficiency in the ABR-UBER (8h HRT,0.5V) was higher than that in ABR-UBER without electrolysis, i.e.95.1±1.5%versus86.9±6.3%. Higher power supply (0.7V) enhanced AYR decolorization efficiency (96.4±1.8%), VFAs removal, and current density (24.1A/m3·TCV). Shorter HRT increased volumetric AYR decolorization rates, but decreased AYR decolorization efficiency. This indicated that each compartment of ABR-UBER could endure a high AYR loading rate, while the capalities of former compartements were the limit fact to the overall performance. The latter compartments still worked well at shorter HRT of4h. The novel ABR-UBER with membrane-free provided a new concept for BES scaling-up to energy-efficient treatment of azo dye wastewater.更多还原