进水磷限制条件下GAOs系统的构建

Construction of GAOs system under phosphorus limitation conditions in feeding

为了研究进水磷限制条件下聚糖菌(GAOs)反应器模型的构建与特征,采用以厌氧-好氧运行的SBR系统,以乙酸为单一碳源,利用高通量测序技术监测了系统种群的动态变化。系统运行前140 d完全限制进水磷酸盐,140 d后进水添加1 mg·L^(−1)(以P计)的磷酸盐作为营养盐用于微生物生长。结果表明,在进水完全进行磷限制的条件下,厌氧阶段几乎没有乙酸的吸收,同时也没有厌氧糖原消耗与PHAs合成,系统无法富集到GAOs;在进水中磷酸盐质量浓度调整为1 mg·L^(−1)并继续运行27 d后,系统显示出典型的聚糖代谢模式,即厌氧阶段乙酸被完全吸收、消耗了0.034 g·g^(−1)的糖原,合成了0.041 g·g^(−1)的PHAs。宏基因组测序结果表明,系统稳定后主要富集到Candidatus Contendobacter这类GAOs,相对丰度占系统的49.4%。污泥镜检结果表明,添加1 mg·L^(−1)磷酸盐后污泥逐渐由松散的絮状转变为颗粒状;由絮状向颗粒状过渡阶段,污泥表面附着大量丝状菌,系统颗粒污泥的形成可能与丝状菌的大量繁殖有关。以上研究结果从微观结构揭示了进水磷限制条件下GAOs的富集过程菌群结构及污泥形态的变化,可为GAOs为主的工艺运行提供参考。

To investigate the construction of GAOs model and its characteristic under phosphorus-limited conditions,a SBR system with anaerobic/aerobic operation was modeled with acetate as single carbon source,many indexes related to reactor performance were measured,and the dynamics of the microbial community was monitored by high-throughput sequencing technology.The results indicated that when the system was operated with complete phosphate limitation for the first 140 days,almost no uptake of acetate occurred in the anaerobic phase,while there was almost no anaerobic glycogen consumption or PHAs synthesis,GAOs could not be enriched in the system.After 140 days,the feeding was supplemented with 1 mg·L^(−1) phosphate as nutrient element for microbial growth,the system showed a typical GAO metabolism on the 167th day.At the anaerobic stage,acetate was completely absorbed,0.034 g·g^(−1) glycogen was consumed,and 0.041 g·g^(−1) PHAs were synthesized.Macrogenome sequencing showed that Candidatus Contendobacter was the dominant community after the stabilization of system,and its relative abundance accounted for 49.4%of the whole community.Microscopy revealed that the sludge gradually changed from loose flocculent to granular after 1 mg·L^(−1) phosphate addition,and a large number of filamentous bacteria attached to the sludge surface at the transition stage from flocculent to granular,suggesting that the formation of granular sludge may be related to the massive reproduction of filamentous bacteria.This study revealed the community structure of GAOs enrichment system and sludge morphology changes under the phosphorus-limited conditions from the aspect of microstructure,which provides a technical support and theoretical basis for the operation of GAOs-based process.