城市污水管网中胞外聚合物的沿程变化特性

通过建立一套长度为1 200 m的城市污水管道中试系统,利用三维荧光、傅里叶红外光谱、微电极和高通量测序等方法,对管网沿程生物膜胞外聚合物(EPS)组分含量、有机物组成特征、生物膜厚度及造成沿程EPS含量变化的原因进行了研究。结果表明,EPS含量随着管网沿程距离的增加呈现先增加后逐渐降低的趋势,生物膜厚度和EPS含量变化趋势相似,且均在600～800 m范围内达到峰值,这说明在管网中EPS对生物膜厚度的增长起着重要的作用。三维荧光和傅里叶红外光谱图显示管网沿程生物膜EPS中主要有机物为类酪氨酸和类色氨酸蛋白类物质,主要官能团为酰胺基、羧基、羟基等。为进一步揭示管网沿程EPS含量变化的原因,利用高通量测序对管网沿程微生物菌群的变化进行了分析,结果表明,管网沿程EPS含量的变化,可能是由于在600～800 m范围内环境条件发生变化不再适宜厚壁菌门(Firmicutes)、螺旋菌门(Spirochaetae)和梭杆菌门(Fusobacterium)等菌门的生存,使得其在竞争中处于劣势地位,并逐渐消亡。由此可知,在管网600～800 m范围大量微生物的消亡和细胞自溶破裂是造成EPS含量变化的主要原因。

Variation Characteristics of Extracellular Polymeric Substances in Urban Sewer System

A study was conducted through a 1 200 m pipe reactor, which was used to simulate the urban sewer system. Three-dimensional fluorescence spectroscopy, Fourier transform infrared spectroscopy, microelectrode method and high-throughput sequencing were utilized to' study the extracellular polymeric substances (EPS) component content, organic matter composition characteristics, biofilm thickness and the reasons for the change of EPS content. The results showed that the EPS content increased .first and then decreased with the increase of the distance along the sewage network, the change trend of the biofilm thickness was similar to that of the EPS content, and both reached the peak value in the range of 600 - 800 m. The EPS played an important role in the growth of biofilm thickness in sewage network. Three-dimensional fluorescence spectroscopy showed that the main organic compounds in the EPS were tyrosine and tryptophan like substances. Fourier transform infrared spectroscopy showed that the main functional groups of EPS were composed of amido group, carboxyl group and hydroxyl group. In order to further reveal the reasons for the change of EPS content along the sewage network, high- throughput sequencing was used to analyze the variation of microbial flora along the sewage network. The results showed that the change of EPS content along the pipeline might be due to the change of environmental condition in the 600 - 800 m range of sewage network, which was no longer suitable for the survival of Firmicutes, Spirochaetae and Fusobacterium, and made it disadvantaged and gradually disappearing in the competition with other bacteria. Therefore, the extinction of a large number of microorganisms and the autolysis of cells are the main reasons for the change of extracellular polymeric substances ( EPS) content in the 600 - 800 m range of the sewer system.