煤气化废水尾水的生物强化处理与微生物响应特性

Effect of bioaugmentation on treatment efficiency of effluent from coal gasification wastewater biotreatment and microbial community

煤气化废水难降解有机物含量高、毒性大,常规生化处理很难达到理想的处理效果。以煤气化废水生化处理出水为研究对象,采用生物菌剂和促生剂来强化煤气化废水的生化处理效果,探讨生物强化的微生物机制。反复批式实验结果表明,单独投加原油降解菌群对废水的化学需氧量(Chemical Oxygen Demand,COD)去除效果最好,与只投加污泥的空白相比,可使3个实验周期内平均COD去除率提高19.7%;单独投加促生剂能使早期出水COD浓度显著下降,但效果难以维持长久;联合投加原油降解菌群和吐温80,可使30 d内COD平均去除率提高21.5%。微生物生态学分析表明,促生剂和菌剂联合强化对煤气化废水中优势菌属Candidatus Competibacter和Defluviimonas的影响较小,但明显增加了系统中的微生物多样性;在微生物互作关系网中,具有较高权重和紧密中心性的Limnobacter和Gaiella是煤气化废水处理系统中的关键物种;香草醛和香草酸盐降解途径是煤气化废水处理系统中微生物的关键降解途径,推测香草醛或香草酸盐是煤气化废水中多种复杂有机物降解的共同中间体或结构类似物。

Coal gasification wastewater is difficult to treat by conventional biological processes due to the high load of recalcitrant organic matter and high toxicity.In this study,a growth promoting agents and bacterial consortia were used to enhance the treatment efficiency of secondary effluent from coal gasification wastewater,and the microbial mechanism of the bioaugmentation was discussed.The results showed that an addition of crude oil degrading-bacteria has a significant positive effect on chemical oxygen demand(COD)removal from wastewater,in which the average COD removal rate during the first three cycles was increased by 19.7%,compared with the control group without bioaugmentation.In contrast,the addition of growth promoting agents can significantly reduce the COD concentration during the first cycle,but the strengthening effects is difficult to maintain for a long time.The average COD removal rate was increased by 21.5%by supplementing both crude oil-degrading bacteria and Tween 80 during the six cycles,compared with the control group without bioaugmentation.It showed that the combined addition of growth promoting agents and bacterial consortia has good stability and sustainability.Furthermore,a high-throughput sequencing analysis showed that the addition of growth promoting agents and bacterial consortia has little effect on dominant genus(such as Candidatus Competibacter and Defluviimona),but significantly increased the diversity of microbial communities.Limnobacter and Gaiella with high weight and closeness centrality are the keystone taxa in the coal gasification wastewater treatment system.Meanwhile,super pathways of vanillin and vanillate degradation are the key degradation pathways of microorganisms,indicating that the vanillin and vanillate may be the common degradation intermediates or their structural analogues of a variety of complex organic compounds in coal gasification wastewater.