醌呼吸协同反硝化降解水中毒性有机物及其机理

The rapid development of industry and agriculture led to increasingly serious surface water and groundwater pollutions by toxic organics, and it appeared complex pollution trends with frequently nitrate-organics pollution. The bioremediation technology of contaminated sites is considered as a most promising solution, in particular through anaerobic bioremediation. Among them, biodegradation by denitrification has obvious advantages in the remediation of nitrate-organics complex pollution. However, some drawbacks, such as lower mineraliztion extent of toxic organics and some accumulation of nitrite and nitrous oxide are found frequently in this process. Based on this, a new idea is proposed for the first time that biodegradation of toxic organics in water through synergistic reaction between quinone respiration and denitrification. The remediation of nitrate-aromatics complex pollution is conducted as the research object, and main contents are included as follows: (1) enrichment and molecular ecological characteristics of efficient quinone respiring and denitrifying consortium (2) kinetic characteristics of aromatics biodegradation by the above consortium under denitrification condition in the presence or absence of typical humic acids in water (3) identification of limit parameters influencing remediation performance of nitrate-organics complex pollution, and the construction of control strategies for the remediation system (4) the synergistic biodegradation mechanism of toxic organics in water is analysed in depth from different angles. .The proposal is involved in environmental engineering, microbial ecology and material science. Some drawbacks in the conventional biodegradation by denitrification can effectively be overcome by the synergistic reaction between quinone respiration and denitrification, consequently enhanced remediation performance of nitrate-organics complex pollution. The proposal will provide a solid basis of novel biotechnology development for both bioremediation of contaminated water and the treatment of refractory organic wastewater.

反硝化生物降解对修复水中硝酸盐和毒性有机物的复合污染具有明显优势。但该过程中存在难降解有机物的矿化程度低以及不同程度的亚硝酸盐和氧化亚氮积累等弊端。基于此，本研究首次提出通过强化醌呼吸与反硝化的协同效应降解水中毒性有机污染物这一新思路。以芳烃为代表性毒性有机物，研究内容包括（1）高效醌呼吸且反硝化降解菌群的富集及其分子生态学特性（2）固定于醌改性陶粒上高效菌群在有无典型水体腐植酸存在下对芳烃的反硝化降解动力学特性（3）识别影响复合污染修复性能的限制性生态因子，建立该修复体系的调控策略（4）多层面地深入探讨醌呼吸协同反硝化降解水中毒性有机物的作用机理。本项目涉及多学科交叉领域，通过醌呼吸与反硝化的协同效应可有效解决反硝化生物降解中的诸多弊端，从而提高水中硝酸盐-毒性有机物复合污染的生物修复效果。这将为研发新型的污染水体生物修复工艺以及难降解有机废水生物处理工艺注入崭新思路和奠定坚实理论基础。

针对反硝化生物修复水中硝酸盐和毒性有机物过程中存在有机物矿化程度低、亚硝酸盐积累等弊端，本研究提出了通过强化醌呼吸与反硝化的协同效应降解水中毒性污染物这一新思路。以苯酚为目标污染物，内容包括（1）高效醌呼吸且反硝化降解菌群的富集及其分子生态学特性（2）固定于醌改性载体上高效菌群在有无腐植酸存在下苯酚反硝化降解动力学特性（3）识别影响复合污染修复性能的限制性因子，建立该修复体系调控策略（4）探讨醌呼吸协同反硝化降解毒性有机物的作用机理。.结果表明，目标菌群的优势菌为Lactococcus sp.，Shewanella sp. 和Pseudomonas sp.。采用共价法制备了醌改性陶粒（AQS-陶粒）和醌改性聚氨酯泡沫（Q-PUF），并将目标菌群吸附至2种载体上，发现Q-PUF体系的苯酚和硝酸盐去除率明显优于AQS-陶粒。不同种类腐植酸对苯酚反硝化降解速率均具有促进作用，其中PP-HA最为明显。当HRT缩短至6 h时，Q-PUF体系的苯酚和总氮去除率稳定在85%和80%左右，未出现亚硝酸盐积累；温度降至15℃时，苯酚和总氮去除率波动较小；进水中含有10 mg/L PP-HA，Q-PUF体系的苯酚和总氮去除率达到了94.5%和90%，比对照均提高了20%以上。Q-PUF体系长期运行后，优势菌为Shewanella sp.和Pseudomonas sp.。C/N和HRT可作为Q-PUF体系修复硝酸盐和毒性有机物复合污染的调控因子。介体存在下，Shewanella sp. 厌氧降解苯酚过程中主要中间产物为乙酸，而且该过程中胞内有聚羟基丁酸酯（PHB）形成。介体强化苯酚反硝化降解的机理：胞外介体通过自身氧化还原循环加速了电子传递，促进了胞内NAD(P)+/NAD(P)H转化，从而加速了苯酚降解以及硝酸盐去除。本项目为研发新型硝酸盐-毒性有机物污染的生物修复工艺奠定了理论基础。