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生物电化学系统强化去除煤化工废水典型污染物及机制研究
Alternative TitleStudy on enhanced removal of typical pollutants in coal chemical wastewater by bioelectrochemical system
杨立辉
Subtype博士
Thesis Advisor王爱杰
2019-06
Degree Grantor中国科学院生态环境研究中心
Place of Conferral北京
Degree Name工学博士
Degree Discipline环境工程
Keyword生物电化学系统,煤化工废水, 协同作用, 微氧,氨回收 bioelectroChemical System (Bes), Coal Chemical Wastewater, Synergetic Interaction, Micro-oxygen Bes, Ammonium Recovery
Abstract

      煤化工废水是一种典型、难以处理的工业废水,其 组成成分复杂,难降解有机物(酚类、含氮杂环类等) 、氨氮等无机污染物 含量高 。 煤化工废水生物处理中 厌氧生物处理具有能耗低、环境友好的特点 在废水处理中发挥重要作用;而 有机 污染物的高毒性、 酚类物质 的 高挥发性 会 对 废水 后续 好氧生物 处理 产生严重影响; 因此, 强化煤化工废水难降解有机物 的 厌氧高效 去除 对 提高废水的整体处理效能具有重要意义 。 近年来, 已 有 研究 将 生物电化学系统( BES 应用于难降解有机物 如 酚类、含氮杂环类 等 物质的去除 。 基于此, 本 文研究 生物电化学系统对煤化工废水 难降解有机物 的 强化去除效能, 以期 提高 煤化工废水 生物处理的 整体效能 。
      本研究面向 “强化煤化工废水 厌氧生物 处理”的需求, 首先, 针对 厌氧 过程难降解有机物降解速率缓慢 问题, 基于生物阳极作为电子受体促进污染物强化去除 原理 ,探究煤化工废水中典型难降解有机物在 BES中强化 去除的 可行性 ,并着重对主要 有机 污染物酚类的 去除 机理 进行研究 其次,依据 酚类 有机物自身分解 去除 机制,通过调整 BES运行参数 ,进一步提高 BES对其强化去除性能 及电子回收效能 最后 利用难降解有机物 降解 去除 回收的电子 实现废水中无机污染物(氨氮)的 高效去除与 有效回收。
      针对难降解有机物降解速率缓慢问题 将BES生物阳极引入厌氧过程,探究BES对煤化工废水中酚类和含氮杂环类有机污染物强化去除的可行性。结果表明,与单独厌氧反应器相比,除污染物对苯二酚以外,其他污染物在BES中均可强化去除。酚类和含氮杂环类在BES中强化去除效果不同,酚类物质矿化率提高 2.3~4.4倍 含氮 杂环类物质矿化率 仅 提高 7.4%~13.3%。 此外,利用实际煤化工废水 对 BES的 强化 处理 效果 进行验证, 废水 COD去除率提高 ~1倍 ,且实际废水中甲基酚类物质也可得到强化去除 。
      间苯二酚在BES中 的强化去除效果和电子回收效能在所测试污染物中最高,且 作为芳香族物质厌氧 降解 的主要中间产物之一, 因此对 间苯二酚在 BES中 的降解 去除 过程 进行着重研究。 间苯二酚的降解去除 主要通过 间苯二酚降解 菌 与 电化学活性菌 间 的 协同作用 完成 间苯二酚降解 菌首先将间苯二酚转化为乙酸,之后乙酸被电化学活性菌群利用产生电流;该 机制 解析补充 并 进一步 完善了芳香族类物质在 BES中的 降解 去除 过程 。
      针对废水中 最为典型的有机污染物 -苯酚 在 BES中 强化去除效果较低问题,设计 开发 了 一种微氧 条件 BES反应装置, 以 进一步提高 BES对 酚类 有机物 强化去除 性能 及电子回收 效能。 结果表明: 与传统厌氧 BES反应器( RAN)相比,微氧 条件 BES反应器( RMO 、微氧切换厌氧BES反应器(RMOA)中苯酚去除率分别提高6倍和1.8倍,电流分别提高4倍和2.3倍。因此,BES反应器先经微氧驯化再以厌氧运行,不仅可以促进苯酚的降解,同时可以提高电流和库伦效率。与此同时,明晰了微量氧气引入使苯酚降解途径发生改变、功能微生物丰度及含量增加是RMO中苯酚去除效果及产电性能提高的重要原因。
针对煤化工废水高氨氮问题,构建生物电化学-透气膜组合系统,利用难降解有机物降解产生的 微小 电流实现废水中无机污染物 -氨氮 的 高效去除与 有效 回收。结果表明 该系统可以同步实现苯酚强化去除和氨氮有效回收。与对照相比,苯酚去除率提高42.8%,氨氮去除率提高1.2倍以及氨氮回收率提高4.4倍。苯酚浓度为200 mg/L,氨氮浓度为100~500 mg/L时,氨氮去除率为2.0±0.0%~96.9±0.5% ,回收率为63.9±6.4%~82.9±4.9%。利用该生物电化学-透气膜组合系统回收氨氮的运行能耗为1.2~4.6 kWh·kgN-1,远低于氨合成工艺Harbor-Bosch所需能耗。该系统为煤化工废水处理及资源化提供了新途径 。

Other Abstract

      Coal chemical wastewater is a typical industrial wastewater which is difficult to treat. Its composition is complex, and the contents of the organic pollutant, such as phenols, nitrogen-containing heterocyclic compounds and inorganic pollutant, such as ammonia nitrogen are high. In the biological treatment of coal chemical wastewater, anaerobic biological treatment plays an important role with the characteristics of low energy consumption and environmental friendliness. The high toxicity of organic pollutants and high volatility of phenolic substances will have a serious impact on the subsequent aerobic biological treatment of wastewater. Therefore, it is of great significance for overall treatment performance to strengthen the anaerobic efficient removal of refractory organic substances in coal chemical wastewater. In recent years, bioelectrochemical systems (BES) have been applied to the removal of refractory organic phenols, nitrogen-containing heterocycles and other substances. Based on this, this research studies the enhanced removal efficiency of bioelectrochemical system for refractory organics in coal chemical wastewater, in order to improve the efficiency of bio-treatment process of coal chemical wastewater
      Aiming at “the need of strengthening anaerobic biological treatment of coal chemical wastewater”, this study firstly explored the feasibility of enhanced removal of typical refractory organic pollutants in coal chemical wastewater by BES, based on the principle of enhanced removal of pollutants by using bio-anode as electron acceptor. The removal mechanism of phenolic compounds in BESs were emphatically studied during the process. Secondly, based on the catabolism mechanism of phenolic compounds, BES operation parameters were adjusted to improve the enhanced removal performance of BES. Finally, the inorganic pollutants (ammonia nitrogen) in wastewater can be effectively removed and recovered by using the small current generated by the degradation of refractory organic compounds.
      In view of the problem of low degradation rate of refractory pollutants in coal chemical wastewater, typical phenolic compounds and nitrogen-containing heterocyclic organics were selected as the model of refractory organics in this study to explore the feasibility of enhanced degradation by BES. Except hydroquinone, all other substances could be enhanced in BES. However, the results of enhanced removal of the two kinds of substances were different. The mineralization efficiency of phenolic substances increased by 2.3~4.4 times, while that of heterocyclic substances increased just by 7.4~13.3%.
      The enhanced removal efficiency and electronic recovery efficiency of resorcinol in BES were the highest among the tested pollutants, and as one of the main intermediates of anaerobic degradation of aromatic substances, the degradation and removal process of resorcinol in BES is emphatically studied. Resorcinol degradation in BES was mainly a synergistic process between resorcinol-degrading bacteria and electrochemically active bacteria. Resorcinol-degrading bacteria first converted resorcinol into acetic acid, and then acetic acid was used by electrochemically active bacteria to generate current. The mechanism of resorcinol degradation in BES supplement and further improve the aromatics decomposition process in BES.
      As phenol is the most typically organic pollutant in coal chemical wastewater and its removal enhancement was poor, a micro-oxygen BES reactor was designed to further improve the efficiency of BES treatment. Compared with the traditional anaerobic reactor (RAN), the phenol removal efficiency of micro-oxygen reactor (RMO) and micro-oxygen anaerobic reactor (RMOA) increased by 6 times and 1.8 times, and the current increased by 4 times and 2.3 times, respectively. Micro-oxygen acclimation first and then anaerobic operation of BES reactor can not only promote the degradation of phenol, but also improve the current and coulomb efficiency. The good performance of phenol removal efficiency and electricity generation in RMO were mainly caused by the following reasons: firstly, the introduction of trace oxygen changes the degradation pathway of phenol; secondly, the increase of biomass and the proportion of phenol-degrading bacteria and electricity-producing bacteria made more functional microorganism playing a role.
      In view of the high content of ammonium in coal chemical wastewater, a bioelectrochemical gas membrane assembly system was constructed to study the enhanced removal and effective recovery of inorganic pollutants - ammonia nitrogen in wastewater by utilizing the tiny current generated by degradation of refractory organic compounds. The results showed that the system could simultaneously realize the enhanced removal of phenol and the effective recovery of ammonium nitrogen. Phenol removal rate increased by 42.2%, ammonium nitrogen removal rate increased by 1.2 times and recovery rate increased by 4.4 times. When the concentration of phenol was 200 mg/L and ammonia nitrogen was 100~500 mg/L, the removal efficiency of ammonia nitrogen was 82.0 0.0%~96.9 0.5%, and the recovery efficiency was 63.9 6.4%~82.9 4.9%. The electricity consumption of ammonia-nitrogen recovery by this system was 1.2~4.6 kWh·kgN-1, which was lower than that of traditional Harbor-Bosch process. This study provided a new method for removal and resource of the coal chemical wastewater.

Pages136
Language中文
Document Type学位论文
Identifierhttp://ir.rcees.ac.cn/handle/311016/42331
Collection中国科学院环境生物技术重点实验室
Recommended Citation
GB/T 7714
杨立辉. 生物电化学系统强化去除煤化工废水典型污染物及机制研究[D]. 北京. 中国科学院生态环境研究中心,2019.
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