人工湿地处理造纸废水后细菌群落结构变化

人工湿地通过模拟自然湿地的生态系统,能够实现污染物的去除,是一种高效经济的污水处理手段,但是对人工湿地处理后污水中细菌群落的研究较少。采集了造纸厂排污口和人工湿地出水口的水样,检测了溶解氧、pH值和盐度等水质指标,对主要污染物的含量进行了测定和分析,并利用DGGE技术对细菌群落的变化进行了研究。结果表明:(1)造纸污水经人工湿地处理后水质有明显提高;(2)人工湿地处理后细菌群落结构发生变化,优势菌由γ变形菌和衣原体变为α变形菌,而且微生物多样性指数Shannon-Wiener's降低;(3)人工湿地处理前污水中存在着大量致病微生物和降解微生物,处理后以环境友好的固氮菌和少量致病菌为主。研究结果揭示了人工湿地不仅可以去除造纸废水中的污染物,改善水质而且可以大大减少向环境中排放的致病微生物,防止由致病微生物引起的生态灾难的发生,为将来人工湿地应用于工业污水处理和微生物生态安全评估提供有效可靠的依据。

The bacterial community changes after papermaking wastewater treatment with constructed wetlands

Constructed wetlands are efficient and economic sewage disposal means, characterized by stimulation of natural wetland ecosystems. They could remove the pollutants of wastewater to achieve purification of sewage, and microbes play an important role in this process. The aim of this study is to investigate bacterial community structure variation after effective wastewater treatment with constructed wetlands. We collected the water samples from the outfall of paper mill and outlet of constructed wetlands, and examined several parameters of the conventional water quality. Using DGGE method and cloning sequencing analysis of dominant microbes, we analyzed the variation of the bacterial community structure and major microbial species in the water samples. The results are as follows: (1)The water quality was greatly improved after papermaking wastewater treatment with constructed wetlands; (2) The structure of bacterial community remarkably changed, showing that the major microbes in the wastewater changed from Gamma-proteobacteria and Chlamydia to Alpha-proteobacteria, with the decrease in the Shannon-wiener's index; (3)Before papermaking wastewater treatment, dominant pathogenic bacteria included Legionella, Klebsiella and Parachlamydia and degrading bacteria included Thioalkalivibrio, Dehalococcoides and Hyphomicrobium. In contrast, the main priority of microbes became environment friendly bacteria such as Mesorhizobium and Rhizobium mostly, and the species and proportion of pathogenic bacteria significantly decreased after treatment with constructed wetlands. These findings suggest that constructed wetlands can not only improve water quality and change the structure of microbial community, but also remove a great deal of pathogens in the wastewater, providing powerful experimental evidence for application of constructed wetlands in industrial wastewater treatment and assessment of microbial ecology safety in the future.