炭质材料改进强化厌氧生物降解偶氮染料废水机理研究

Anaerobic - aerobic biological process for the treatment of dyeing wastewater is the development trend, in which the anaerobic biodegradation of dyes is the principal limiting factor of its reaction rate. The carbonaceous materials, for example, activated carbon, activated carbon fiber and graphite, are modified as the redox mediums (RM) to improve the rate of electron transport and degradation of azo dyes in this work. In the subject, the carbonaceous materials are modified for improving their physical and chemical properties to increase their surface reactive functional groups. The surface properties and structural features of the carbonaceous materials are comprehensively characterized by the modern analysis technologies, such as low-temperature nitrogen adsorption, TEM, SPM, AFM and Raman spectrum, etc., for revealing the mechanisms of the electron shuttle and dye degradation among the carbonaceous materials, microorganisms and the substrate (azo dye). Using catalytic theory, the mechanism of the active sites in the RM of the carbonaceous materials impact on azo dye reduction reaction is studied. The degradation products and relative parameters during reaction processes, the dye degradation pathway and the synergetic mechanism of the enhanced biochemical reduction reactions are analyzed, respectively. According to mass transfer and relative reaction mechanisms in multiphase reaction system, the reaction kinetic model of anaerobic biodegradation of azo dye in the system of RM is built. The subject is undoubted of having significant research value and application prospect, and it would provide some innovative ideas and reference for the treatment of the bio-recalcitrant wastewater (e.g. dyeing wastewater).

厌氧-好氧生物组合工艺是有效处理难降解印染废水的发展方向，而厌氧生物处理是其反应速率的限制因素。拟采用改性活性炭、活性碳纤维和石墨等炭质材料作为氧化还原介质（RM），以提高厌氧生物降解典型偶氮染料的速率。本项目通过炭质材料改性，改善炭质材料的物化性能和孔结构，强化其表面活性官能团。综合应用低温N吸附、TEM、SPM、AFM和Raman光谱等分析手段系统表征炭质材料表面和结构特性，有效揭示炭质材料和微生物及染料之间电子传递过程和降解机理；运用催化理论研究炭质材料的RM活性位点与促进偶氮染料降解/还原反应的机制，分析厌氧生物还原反应过程中染料降解产物和相关参数变化规律，揭示染料降解途径和RM强化与促进还原反应的机理；根据多相反应体系组分的传质及相关反应机理，建立厌氧生物降解偶氮染料系统的生化反应动力学模型。为染料等难降解废水的厌氧生物处理提供新的思路与借鉴，极具理论研究价值与实际应用前景。

厌氧—好氧生物组合工艺是有效处理难降解印染废水的发展方向，而厌氧生物处理是其反应速率限制因素。本项目采用改性活性炭、活性碳纤维和碳纳米管等碳质材料作为氧化还原介质（ RM），以提高厌氧生物降解典型偶氮染料的效率。通过高温改性、酸碱改性及HNO3氧化改性等方式对碳质材料（如改性活性炭、活性碳纤维、碳纳米管、石墨烯）进行改性，综合应用低温N吸附、 TEM和 Raman 光谱等分析手段系统表征炭质材料表面和结构特性，研究结果表明改性处理可以提高碳质材料表面含氧官能团含量，改变表面性质，提高其作为氧化还原介体作用。在染料/硫化钠（或过硫酸盐）体系中加入改性碳质材料后，偶氮染料脱色速率快速提升，说明碳质材料具有RM功能促进电子转移。在染料/硫化钠体系中，碳质材料可以加速电子从硫化钠转移至染料进而促进还原脱色，产生以含N类芳香族化合物和芳香胺类物质为主的有毒有害类物质；在染料/过硫酸盐体系中，碳质材料表面官能团（如碳基、含氮官能团）加速电子转移至过氧键，催化断裂产生硫酸根自由基，进而使染料氧化脱色，中间产物主要以含氧类芳香物为主，并可进一步氧化为小分子酸甚至矿化。通过静态摇瓶实验，研究厌氧生物反应系统中改性碳质材料对染料降解的影响；结果表明碳质材料投加后显著促进体系染料厌氧脱色，如碳纳米管对偶氮染料AO7脱色速率提升了3.5倍，且染料降解过程符合一级动力学；电子供体类型对染料降解有较大影响，混合碳源或者甲酸钠碳源为最佳电子供体；染料降解速率随着污泥浓度、碳质材料投加量、碳源投加量的增加而提高；碳质材料作为RM仅加速了电子传递速率，并未改变染料降解途径。在连续流UASB反应器中，投加碳质材料同样可以促进染料厌氧生物降解；通过运行过程参数调控和优化，实现反应器稳定运行和染料高效脱色。本项目为染料等难降解废水的厌氧生物处理提供新的思路与借鉴，极具理论研究价值与实际应用前景。