煤气废水有机污染物缺氧生物降解性能及机理

Treatment of typical organic pollutants by acclimated activated sludge under anoxic conditions

摘要:

为考察煤制气废水3种典型有机污染物（喹啉、吡啶、邻苯二酚）的缺氧生物降解性能及降解途径,利用缺氧驯化污泥作为接种污泥,以硝态氮为电子受体,考察了3种有机物的缺氧降解过程,并利用UV-Vis和GC/MS分析3种物质缺氧降解机理.结果表明：3种污染物对缺氧微生物抑制与毒害作用随初始质量浓度增加而增强；缺氧降解48 h后,剩余底物质量浓度随初始质量浓度增加而增大；3种污染物缺氧生物降解速率常数大小顺序为吡啶 > 邻苯二酚 > 喹啉.缺氧降解中污染物未被完全氧化成CO₂和H₂O,部分生成了较底物自身降解性更差的中间产物.葡萄糖共基质可以提高难降解污染物缺氧降解性能,且共代谢作用对自身生物降解性差的污染物降解性能的提高更显著.利用UV-Vis和GC/MS分析了污染物缺氧生物降解途径,结果表明,喹啉和吡啶的降解均始于分子羟基化反应.污染物定量结构-生物降解性关系(QSBR) 研究表明,3种物质的缺氧降解速率常数K_s与分子连接性指数¹Xv 和前线最高占据轨道能EHOMO 有很好的相关性.

Abstract:

In order to investigate the anoxic biodegradability and degradation pathway of three typical organic pollutants (quinoline, pyridine and catechol) in coal gasification wastewater, the acclimated anoxic activated sludge used as seeded sludge with NO₃--N as electron acceptor, and the anoxic degradation intermediates of the three pollutants were determined by UV-Vis and GC/MS analysis. Results showed that the inhibitory and toxic effects of the three compounds strengthened with the increase of the initial concentration. The residual concentration with the of its initial concentration 48 h anoxic treatment. The anoxic degradation rate constants of the three pollutants in descending order were pyridine, catechol and quinoline. The pollutants were partly converted into intermediates which were more refractory than the original compounds, instead of being mineralized to CO₂ and H₂O. The anoxic biodegradability of these pollutants enhanced with the addition of glucose as co-substrate. The co-metabolism effects were more significant when the pollutants were more refractory. The degradation of quinoline and pyridine initiated with the hydroxylation reaction. The possible degradation pathways were proposed based on the intermediates analysis. QSBR studies of the above three compounds showed that biodegradation rate constant (K_s) was significantly correlated with molecular connectivity indices ¹X^v as well as highest occupied molecular orbital EHOMO.