城市供水管网铁释放特性及其风险管理

发布时间：2018-06-26 00:00

  本文选题：铁释放 + 管道腐蚀产物　； 参考：《哈尔滨工业大学》2015年博士论文

【摘要】：供水管网水质安全是当前供水行业的热点问题之一,随着研究的逐步深入,供水管道铁腐蚀和铁释放已变成了两个意义不同的概念。本文首先进行了城市供水管道腐蚀产物的物理化学特性和管道铁释放规律的研究,然后,从铁形态学角度,进行了管道中铁的迁移转化研究,之后,基于铁释放机理分析,建立了管道铁释放通量模型和城市供水管网铁释放风险评价体系,最后提出了控制管道铁释放的管理措施。实验数据说明城市旧有水源出厂水水质腐蚀性较高,从而导致管段内壁腐蚀严重,形成了发达且分层的腐蚀管垢层。铸铁管和镀锌钢管腐蚀产物的主要元素均为铁和氧,两种元素在铸铁管和镀锌钢管腐蚀产物中的质量百分比之和分别平均大于80%和90%。晶态铁氧化物主要是磁铁矿、针铁矿、纤铁矿、四方纤铁矿、绿锈和菱铁矿,但是,在不同的管道腐蚀产物中,晶态铁氧化物的含量存在差异。硫酸根浓度从30mg/L提高到195mg/L和氯离子浓度从10mg/L提高到190mg/L,管道铁释放速率均明显上升；pH值从7.05提高到8.25和碱度从125mg/L提高到185mg/L,管网铁释放均得到有效控制；溶解氧在8.0mg/L到16.0mg/L范围内变化,铁释放速率先下降后上升；余氯在0mg/L到1.9mg/L范围内变化,铁释放先抑制再促进后趋于稳定。在管网的运行管理中,水流方向的改变会在短时间对铁释放产生剧烈的影响；流速在超出一定临界值之后,流速变大,铁释放量随之变大；随着水力停留时间的延长,管道铁释放量增加程度明显。通过7-12月份长达140多天的长期检测管网铁浓度变化和相关水质指标,分析发现温度是影响管网季节变化中铁释放的重要因素。硫酸根和氯离子对二价铁氧化速率影响微弱；pH值从7.03提高到7.89,二价铁氧化速率急剧上升；在恒定pH值条件下,溶解氧从2.49mg/L提高到8.46mg/L,二价铁氧化速率变化不大；碱度提高,二价铁氧化速率会变大；一氯胺在0～1.12mg/L范围内升高,二价铁氧化速率随之变大。管网水体中铁颗粒物与浊度存在正相关性。硫酸根和氯离子分别在34-389mg/L和9-292mg/L变化,铁颗粒物的形成量变化不大；pH值从7.03提高到7.89,铁颗粒物的形成量上升；溶解氧从2.49mg/L提高到8.46mg/L,铁颗粒物的形成量变化不大；碱度从118mg/L提高到247mg/L,铁颗粒物的形成量上升；一氯胺在0～1.12mg/L范围内升高,铁颗粒物的形成量随之增加；随着时间的累积,铁颗粒物的形成量也会逐渐增加。在管道铁释放较高阶段,管道腐蚀产物中的总铁以及游离氧化铁含量较高,不稳定铁化合物和过渡态铁化合物含量会上升,随着水温下降以及溶解氧、pH、碱度等逐渐上升,管道铁释放水平下降,管道腐蚀产物中的总铁以及游离氧化铁含量也随之降低,不稳定铁化合物和过渡态铁化合物同时被缓慢氧化,形成稳定的磁铁矿和针铁矿。硫酸根在净水工艺中基本没有变化,氯离子只在预氯化和混凝阶段略有增加,碱度在混凝阶段有所下降,但是氯离子和碱度的变化均微弱。pH在混凝过程中会有所下降,溶解氧会受到臭氧工艺的影响。拉森指数随着混凝剂投加量的增加而上升；在研究期间的8月份到11月份,碳酸钙沉淀势CCPP在时间上呈现上升趋势,在工艺单元中变化微弱。采用一维移流扩散方程和物料平衡方法两种方式,建立了城市供水管网铁释放通量模型,通过比较管道铁释放量的实测值与管网铁释放通量模型的预测值,两者的绝对误差在-0.008-0.019mg/L,相对误差在-6.74-7.77%,该模型对管道系统的铁释放预测较为准确。基于管网铁释放的不确定性,结合系统工程和运筹学知识,建立了城市供水管网铁释放风险模糊评价体系,力求表达供水管网水体中铁浓度存在的风险状况,优化日常铁检测取样点位置和便于供水行业运行管理。针对南水北调中线工程通水后的天津市城市供水管网铁释放风险问题,从管道腐蚀产物的物理化学特性,水质特点与水力条件三方面分析,在做好水源地水质保护和长距离输水管渠水质不被污染的前提下,城市供水管网不会发生大面积的“黄水”现象。但是,需要做好管网供水分界线和重点管段的水质安全保障。
[Abstract]:The water quality safety of the water supply network is one of the hot issues in the current water supply industry. With the gradual deepening of the research, the iron corrosion and iron release of the water supply pipeline have become two different concepts. Firstly, the physical and chemical properties of the corrosion products of the urban water supply pipeline and the law of the release of the iron in the pipeline are studied, and then, from the iron morphology angle. On the basis of the analysis of iron release mechanism, the Guan Daotie release flux model and the iron release risk assessment system of urban water supply network were established. Finally, the management measures to control the release of iron in the pipeline were put forward. The experimental data showed that the water quality of the old water source in the city was highly corrosive, thus leading to the result of the experimental data. The corrosion of the inner wall of the tube formed a developed and stratified corrosion scale. The main elements of the corrosion products of cast iron pipes and galvanized steel pipes are iron and oxygen. The percentage of the two elements in the corrosion products of cast iron pipes and galvanized steel pipes is more than 80% and 90%. crystalline iron oxides are mainly magnetite, goethite and fibrite. Tetragonal iron ore, green rust and siderite, but there are differences in the content of crystalline iron oxide in different pipeline corrosion products. The release rate of pipe iron is obviously increased from 30mg/L to 195mg/L and the concentration of chloride ion from 10mg/L to 190mg/L, and the pH value increases from 7.05 to 8.25 and alkalinity increases from 125mg/L to 185mg/L. The release of iron in the pipe network is effectively controlled, the dissolved oxygen changes in the range of 8.0mg/L to 16.0mg/L, the release rate of iron decreases first and then rises, and the residual chlorine changes in the range of 0mg/L to 1.9mg/L, and the release of iron is suppressed first and then then tends to stabilize. When the flow velocity exceeds a certain critical value, the flow velocity becomes larger and the release amount of iron becomes larger. With the prolongation of the hydraulic retention time, the release of iron in the pipeline increases obviously. Through a long period of more than 140 days in 7-12 days, the iron concentration changes and the related water quality indexes are detected, and the results show that the temperature is influenced by the iron release in the seasonal change of the pipe network. The effect of sulphate and chloride ions on the oxidation rate of two valent iron is weak, the pH value increases from 7.03 to 7.89, the oxidation rate of two valence iron oxide increases sharply, and the dissolved oxygen is increased from 2.49mg/L to 8.46mg/L under constant pH value, and the rate of two valence iron oxidation is not changed little; the oxidation rate of two valence iron will increase with the increase of alkalinity; and the one chloramine is 0. The oxidation rate of two iron oxide increases with the increase of 1.12mg/L range. The iron particles and turbidity are positively correlated with the iron particles in the pipe network. The variation of the sulfate and chlorine ions in 34-389mg/L and 9-292mg/L, the formation of iron particles is little, the pH value increases from 7.03 to 7.89, the formation of iron particles increases, and the dissolved oxygen is increased from 2.49mg/L. At 8.46mg/L, the formation of iron particles changed little; the alkalinity increased from 118mg/L to 247mg/L, the formation of iron particles increased; the formation of iron particles increased in the range of 0 to 1.12mg/L, and the formation of iron particles increased with the accumulation of time. The content of total iron and free iron oxide in the corrosion products is higher, the content of unstable iron compounds and transition iron compounds will rise. With the decrease of water temperature and dissolved oxygen, pH, alkalinity and so on, the release level of pipe iron decreases, and the total iron and free iron oxide content in pipeline corrosion products also decrease, and the ironchemical compound is unstable. The iron compounds and transition states were slowly oxidized to form stable magnetite and goethite. The sulphuric acid roots did not change basically in the water purification process, and the chloride ions only slightly increased in the prechlorination and coagulation stages, and the alkalinity decreased in the coagulation stage, but the changes of chloride ions and alkalinity decreased in the process of coagulation, which decreased in the coagulation process. The dissolved oxygen is affected by the ozone process. The Larsen index increases with the increase of coagulant dosage; in the period of August to November, the CCPP of the calcium carbonate precipitate potential is on the rise in time, and the change is weak in the process unit. The city is established by two ways of using the one-dimensional flow diffusion equation and the material balance method. The iron release flux model of the water supply pipe network, by comparing the measured value of the pipeline iron release and the prediction of the iron release flux model of the pipe network, the absolute error between the two is -0.008-0.019mg/L, the relative error is in the -6.74-7.77%, the model is more accurate to the iron release prediction of the pipeline system. With the knowledge of operational research, the fuzzy evaluation system of iron release risk in urban water supply network is established to express the risk of iron concentration in water supply network, optimize the location of the daily iron detection sampling point and facilitate the operation and management of the water supply industry. The risk of iron release from the urban water supply network of Tianjin city after the middle route of the south to North Water Transfer Project is released. From the three aspects of the physical and chemical characteristics of the pipeline corrosion products, the water quality characteristics and the hydraulic conditions, the urban water supply network will not have a large area of "yellow water" on the premise of the water quality protection and the water quality of the long distance water pipeline. However, it is necessary to do well the dividing line and the key pipe section of the pipe network. Water quality safety guarantee.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU991.33
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本文编号：2068118