低流速工况下供水管道铁释放的影响机理及控制措施研究

发布时间：2018-10-08 16:52

【摘要】：在供水管网系统的末梢普遍存在滞流和小流速工况,也是铁释放引发的“黄水”事件多发工况,其发生机理和解决措施亟待深入研究。本课题依托建设在浙江省JX市供水管网的中试实验平台,以不同管径和管材的供水管道为研究对象,通过模拟滞流和小流速工况,结合传统平板培养计数和现代化分子生物学技术来研究铁释放影响机理以及控制措施。主要结论如下:(1)滞流工况下供水管道内壁不同空间位置上铁释放变化规律与微生物群落的相互关系HDPE管道生物膜中微生物群落多样性要高于球墨铸铁管,而且HDPE管道不同空间位置的微生物群落含量分布较为均匀变化不大,而球墨铸铁管变化较大。从IOB和SRB的数量变化可以发现管道内壁中部和下部的增加量最大,上部最小。供水管道内壁中部释放的铁含量最多,这与腐蚀功能细菌IOB、SRB、SOB等存在较大关系。(2)滞流工况下不同管材/管径的管网水铁释放与腐蚀微生物变化规律及相关性管网水中溶解氧,余氯等水质参数不断衰减导致水体中总铁浓度增大,铁氧化细菌和硫酸盐还原菌数量随滞流时间不断增加。主要菌门Proteobacteria在滞流之后达到86.69%-91.36%,主要由Alphaproteobacteria、Betaproteobacteri 和Actinobacteria组成。通过相关性分析和 RDA分析发现与总铁释放存在较强的正相关关系的细菌群落有Proteobacteria、Actinobacteria和Acidobacteria 以及在纲水平上的数据为 Alphaproteobacteria、Betaprotebacteria 和 Bacilli,从环境因子的角度出发发现影响这些细菌群落生长的水质参数有硝酸根、亚硝酸根、TOC、COD、氨氮和溶解氧。(3)不同渗流流速管网水水质变化规律及微生物群落关联性水质指标余氯、溶解氧和氧化还原电位随着水流流速的增大衰减减缓,pH、浊度以及总铁浓度增长则受到抑制,当水流流速增大到临界流速时,这些指标则趋于稳定。IOB和SRB的数量随渗流流速增大而减少,当流速达到一定值时其数量保持恒定。从门、纲和属水平上分析微生物群落同样可以发现,微生物群落结构随流速增大而逐渐趋于稳定。累计总铁释放量和总铁释放速率在随着流速增大至约占临界流速的40%时达到最大阈值。(4)滞流及小流速工况下的铁释放控制措施建议针对滞流小流量工况下的铁释放问题的基础上,建议以下措施控制铁释放:a)优先管道材料;b)球墨铸铁管滞流时间不宜超过8小时,HDPE管不宜超过8-16小时;c)有针对性的选择消毒剂;d)优化水处理工艺加强去除氨氮、TOC等物质;e)水体处于一定程度流动可以有效减少铁释放。
[Abstract]:Stagflation and small velocity are common in the end of water supply network system, which is also the frequent condition of "yellow water" event caused by iron release. Its occurrence mechanism and solving measures need to be deeply studied. Based on the pilot-scale experimental platform of water supply network in JX City, Zhejiang Province, this paper takes the water supply pipeline with different pipe diameter and pipe material as the research object, and simulates the stagflation and small velocity conditions. Combined with traditional plate culture counting and modern molecular biology technology, the mechanism and control measures of iron release were studied. The main conclusions are as follows: (1) the relationship between the variation of iron release and the microbial community in different spatial positions of the inner wall of the water supply pipeline under stagflation condition is higher than that in the ductile iron cast iron pipe in the biofilm of HDPE pipeline. Moreover, the distribution of microorganism community in different space of HDPE pipeline changed little, but that of ductile iron pipe changed a lot. From the changes of IOB and SRB, it can be found that the increase in the middle and lower part of the inner wall of the pipeline is the largest and the upper part is the least. The iron content in the middle of the inner wall of the water supply pipeline is the most, which is related to the corrosion function bacteria IOB,SRB,SOB and so on. (2) the variation law of iron release and corrosion microorganism and the dissolved oxygen in the related pipe water under different pipe / pipe diameter under stagflation condition. The decay of residual chlorine and other water quality parameters led to the increase of total iron concentration, and the number of ferric oxidizing bacteria and sulfate reducing bacteria increased with the stagflation time. The main phylum Proteobacteria, mainly composed of Alphaproteobacteria,Betaproteobacteri and Actinobacteria, reached 86.69- 91.36 after stagflation. By correlation analysis and RDA analysis, it was found that the bacterial communities with strong positive correlation with total iron release were Proteobacteria,Actinobacteria and Acidobacteria, and the data at the class level were Alphaproteobacteria,Betaprotebacteria and Bacilli, from the point of view of environmental factors. The water quality parameters for bacterial community growth are nitrate, TOCCOD, ammonia nitrogen and dissolved oxygen. (3) variation of water quality in pipe network with different seepage velocity and residual chlorine as a related index of microbial community. The dissolved oxygen and redox potential decrease with the increase of the flow velocity, but the increase of turbidity and total iron concentration is restrained. When the flow velocity increases to the critical flow rate, These indexes tend to be stable. IOB and SRB decrease with the increase of flow velocity, and keep constant when the flow rate reaches a certain value. It can also be found that the structure of microbial community tends to be stable with the increase of velocity of flow when we analyze the microbial community at phylum, class and genus level. The accumulative total iron release and the total iron release rate reach the maximum threshold when the velocity increases to about 40 percent of the critical flow velocity. (4) the iron release control measures under the condition of stagflation and small flow rate suggest that the iron release under the condition of stagflation and small flow rate should be targeted at the condition of stagnant flow and small flow rate. On the basis of the question, It is suggested that the following measures should be taken to control iron release: a) priority pipeline material b) ductile iron pipe should not exceed 8 hours or more than 8 hours HDPE pipe should not exceed 8-16 hours; targeted selective disinfectant d) optimized water treatment process to enhance removal of ammonia nitrogen and TOC The release of iron can be effectively reduced when the water is flowing to a certain extent.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU991.36

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