生物膜法强化净化氨氮污染水体及其微生物群落解析

Purification of ammonia-polluted water through biofilm augmentation: operating conditions and key microbial community

摘要:

【目的】比较不同营养条件及挂膜方式下生物膜法对氨氮污染水体的净化效果及其功能微生物群落结构。【方法】设置空白(Blank)、自然成膜(Raw)、预附脱氮菌强化挂膜(PCC) 3组生物膜反应器，利用末端限制性片段长度多态性(T-RFLP)技术和非度量多维标度(NMDS)分析方法对生物膜反应器转化氨氮过程中微生物群落结构及其演替过程进行动态解析。【结果】在C/N=1:1时，除PCC在起始阶段短暂具有较高的氨氮脱除效率外，Blank、Raw和PCC最终均表现出较低的氨氮转化效率(10%?20%)。改变C/N=2:1后，Raw和PCC对人工合成污水中NH4+-N的转化率均提高至95%以上，而且Raw与PCC的群落结构在C/N=2:1时具有较高的相似性，优势菌群主要为γ-变形菌纲(Gammaproteobacteria)、放线菌纲(Actinobacteria)和硝化螺菌纲(Nitrospira)。【结论】C/N是影响生物膜反应器氨氮去除效果及驱动生物膜反应器中细菌群落结构发生改变的重要因子。

Abstract:

[Objective] We compared the effect of nutritional conditions and start-up method on the biofilm augmented purification performance of ammonia-polluted water and the microbial community structures. [Methods] The effect of ammonia removal was tested in three lab-scale reactors, including control reactor (Blank), biofilm reactor with the raw carrier (Raw) and biofilm reactor with the functional bacteria-immobilized carrier (PCC). The microbial community structures were assessed by terminal restriction fragment length polymorphism and the succession process of community was analyzed using the plot of nonmetric multidimensional scaling. [Results] When the C/N ratio was kept at 1:1 for 25 days, the ammonia removal efficiency was only 10%?20% for all the reactors, except for that the PCC showed a temporary high efficiency in the first 5 days. However, the ammonia removal efficiencies of both the Raw and PCC were higher than 95% when the C/N ratio was adjusted to 2:1. The NMDS results showed that the microbial structures of Raw and PCC had high similarity when the C/N was 2:1, and the dominant bacteria were composed of Gammaproteobacteria, Actinobacteria and Nitrospira. [Conclusion] The C/N ratio is not only a key factor impacting on the ammonia removal efficiencies of biofilm augmentation but also a driving force for the shifts of microbial community structures in the biofilm reactors.