给水管网水力条件对初期生物膜形成的影响

发布时间：2018-01-27 04:00

本文关键词： 水力条件生物膜胞外聚合物表面附着给水管网　出处：《合肥工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：给水管网是一个复杂的、时刻变化的生态反应系统,其中的细菌会通过表面附着和聚集的方式(多以生物膜出现)以适应不断变化的环境条件,严重威胁供水水质安全。目前,关于水力条件对给水管网生物膜形成影响的研究仍存在较多争议,其中水力条件如何调控细菌个体行为进而影响初期生物膜形成的机理尚不清晰。本文以给水管网细菌为研究对象,解析不同流速条件下细菌胞外聚合物的分泌、种群分布以及初期附着和聚集机制,揭示生物膜的形成机制,以期为给水管网细菌生长控制提供理论指导和新的思路。首先,本文研究了恒定水力条件下流速对给水管网细菌胞外聚合物分泌与初期生物膜形成的影响。结果表明:在流速较低(0.0-1.0 m/s)时,增大流速会刺激细菌胞外聚合物的分泌进而促进其附着聚集;但当流速过高(1.0 m/s)时,增大流速抑制细菌胞外聚合物的分泌从而抑制其附着聚集。主体水悬浮细菌胞外聚合物分泌量与表面Zeta电位和疏水性的相关,进一步说明了水力条件调控了细菌胞外聚合物的分泌,改变了细菌表面特征,进而影响其在管壁表面的初期附着行为。其次,研究了流速波动对给水管网细菌胞外聚合物分泌和初期生物膜形成的影响。结果表明:相较于恒定水流流速条件,给水管网流速波动促进管壁初期生物膜的形成和主体水悬浮细菌数量的增长,且流速波动幅度和频率越大越有利于管壁生物膜的形成;同时,给水管网水流流速波动促进了细菌EPS的分泌,且随着波动幅度和频率的增大,细菌EPS的分泌量进一步提高;水流流速波动调控着细菌EPS的分泌,改变细菌表面Zeta电位和疏水性,从而影响给水管网初期生物膜的形成。最后,研究了水流流速对给水管网生物膜种群结构和多样性的影响。结果表明:中等流速条件(1.0 m/s)下,生物膜群落结构呈现较高的多样性。在不同流速条件下,铜绿假单胞菌菌属始终为生物膜优势菌种,且在中等流速(1.0 m/s)条件下,其优势最明显。
[Abstract]:The water supply network is a complex and ever-changing ecological response system in which bacteria can adapt to changing environmental conditions by means of surface adhesion and aggregation (mostly as biofilms). At present, there are still many controversies on the influence of hydraulic conditions on biofilm formation in water supply networks. It is not clear how hydraulic condition can regulate the individual behavior of bacteria and then affect the formation of biofilm in the early stage. In this paper, the bacteria in water supply network were taken as the research object to analyze the secretion of extracellular polymer under different flow rates. Population distribution and initial attachment and aggregation mechanism to reveal the biofilm formation mechanism in order to provide theoretical guidance and new ideas for the control of bacterial growth in water supply networks. The effect of flow rate on extracellular polymer secretion and biofilm formation of bacteria in water supply network was studied under constant hydraulic conditions. The results showed that at a low velocity of 0.0-1.0 m / s. Increasing the flow rate stimulates the secretion of extracellular polymers and promotes the aggregation of extracellular polymers. But when the velocity is too high (1.0 m / s). The increase of flow rate inhibited the secretion of extracellular polymers and thus inhibited the aggregation of extracellular polymers. The amount of extracellular polymers secreted by water suspension bacteria was related to the surface Zeta potential and hydrophobicity. It is further explained that hydraulic conditions regulate the secretion of extracellular polymers of bacteria, change the surface characteristics of bacteria, and then affect the initial adhesion behavior of bacteria on the surface of tube wall. Secondly. The effect of flow rate fluctuation on extracellular polymer secretion and biofilm formation of bacteria in water supply network was studied. The velocity fluctuation of water supply network promotes the formation of biofilm in the initial stage of the pipe wall and the increase of bacteria number in the main water suspension, and the greater the fluctuation amplitude and frequency of the velocity is, the more favorable the biofilm is. At the same time, the fluctuation of water flow velocity in water supply network promoted the secretion of bacterial EPS, and with the increase of fluctuation amplitude and frequency, the secretion of bacterial EPS was further increased. The fluctuation of flow velocity regulates the secretion of bacterial EPS, changes the surface Zeta potential and hydrophobicity of bacteria, thus affects the formation of biofilm in the initial stage of water supply network. The effect of flow velocity on the population structure and diversity of biofilm in water supply network was studied. Under different flow rates, Pseudomonas aeruginosa was always the dominant biofilm species, and the dominant biofilm was the most obvious under the medium velocity of 1.0 m / s.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU991.33

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