备用水源原水管道水质及生物膜群落结构变化

Changes of Water Quality and Biofilm Community Composition in Raw Water Pipeline of Emergency Water Source

备用水源原水管道较为封闭,原水停留时间过长会导致溶解氧(DO)浓度降低,管道环境由好氧变为缺氧甚至厌氧,从而引起水质恶化。实验室模拟M、N两种不同水源条件在原水管道的备用状态,以DO降至2 mg/L确定停留时间,探究相应的水质变化以及原水的化学稳定性和管壁微生物群落多样性。结果表明,DO在水质较差水源条件下的衰减时间明显短于水质较好的水源。两种水源水都具有严重腐蚀性,出水pH、总碱度和钙硬度均显著升高。M装置进水水质相对较差,微生物存在水平高,对有机物的去除率更高,COD_(Mn)和UV_(254)的去除率分别为27.8%和22.9%,而N装置分别为24.6%和21.4%;M装置中的硝化作用更强,NO_(3)^(-)-N生成率为23.4%,而N装置为16.2%。两组装置管壁生物膜中的优势菌门基本相同,但丰度较高的菌门差异较大,而丰度较低的菌门差异不明显。较高的NH4+-N浓度有利于增加硝化螺旋菌门的丰度,从而促进硝化作用。良好的水质可以增加管道内的微生物多样性,更有利于管道内生态系统的稳定。

The raw water pipeline of emergency water source is relatively closed.Long hydraulic retention time of raw water in the pipeline will lead to the decrease of dissolved oxygen(DO),and change the environment of the pipeline from aerobic to anoxic or even anaerobic,resulting in the deterioration of water quality.The state of the raw water from two different water sources was simulated in two laboratory reactors M and N.The retention time was determined by reducing the DO to 2 mg/L,and the corresponding water quality change,chemical stability of the raw water and diversity of the microbial community on pipe wall were investigated.The decay time of DO in source water with poor water quality was obviously shorter than that in source water with good water quality.The water from both sources was highly corrosive,and the effluent pH,total alkalinity and calcium hardness were all significantly increased.Reactor M had poor influent quality,high microbial concentration and higher removal rate of organic matter.The removal rates of COD_(Mn) and UV_(254) in reactor M were 27.8%and 22.9%,respectively,while those were 24.6%and 21.4%in reactor N.Reactor M had stronger nitrification ability,in which the generation rate of NO_(3)^(-)-N was 23.4%,while that was 16.2%in reactor N.The dominant bacterial phyla in biofilm on the pipe wall of the two rectors were basically the same.However,the phyla with higher relative abundance were quite different,while the difference of phyla with lower relative abundance was not obvious.Higher NH4+-N was conducive to increasing the abundance of Nitrospira,thus promoting the nitrification reaction.Good water quality increased the microbial diversity in the pipeline,which was more conducive to the stability of the ecosystem in the pipeline.