城市供水管网铁稳定性控制研究进展

针对当前城市供水管网中铁释放引发的管网水质问题,重点阐述了供水管网中铁释放的机理,总结了管网水力条件、生物因素及化学因素对铁释放的影响规律及管网水铁释放控制技术措施,并对城市供水管网铁稳定性控制的研究方向进行展望。     

城市供水管网铁稳定性控制研究进展

针对当前城市供水管网中铁释放引发的管网水质问题,重点阐述了供水管网中铁释放的机理,总结了管网水力条件、生物因素及化学因素对铁释放的影响规律及管网水铁释放控制技术措施,并对城市供水管网铁稳定性控制的研究方向进行展望。     

水源切换对供水管网铁释放影响及控制技术研究进展

针对南水北调通水后北方受水区城市水源切换引起铁释放的问题,通过阐述管网腐蚀机理,重点从水质条件和水力条件分析了水源切换过程中影响水质稳定性的因素。在此基础上,从管网管理、管网改造与维护、管网水质调节技术三方面,提出了水源切换引起管网铁释放的控制措施和建议。     

低pH低碱度水源水引起供水管网黄水的控制措施

针对我国南方水源水低pH值、低碱度水质特征引起供水管网"黄水"问题的控制技术开展了系统研究,确定了管网水pH调节技术和余氯保持技术为经济可行的控制措施。研究结果表明,提高管网水pH值对铁释放具有明显的控制作用,且总铁释放量与pH值呈现出显著负相关性。采用Ca(OH)2调节管网水pH值对铁释放的控制效果略优于NaOH,分析原因是投加Ca(OH)2在提高管网水pH值的同时增加了管网水的硬度,有利于管垢稳定性。保持管网水较高的余氯浓度对管网铁释放具有一定的控制作用。     

基于数据驱动的金属供水管网铁腐蚀预测模型研究

供水管网铁腐蚀是影响末端水质可接受性的重要因素。根据管网水质构建的管网铁腐蚀预测模型对有效发挥水厂水质调控功能,保持管网水质化学稳定性及管网维护具有重要应用价值。根据上海市某供水系统管网水质和管壁铁腐蚀的大量监测数据,分别采用多元回归法、逐步回归法和线性回归法构建了供水管网铁腐蚀预测模型,并比较了模型误差。结果表明,水体p H值、Cl-和SO24-含量为管壁铁腐蚀的主要影响因素;逐步回归模型的模拟效果最好,该模型具有公式简单和预测误差小的优点,在95%置信度下,预测值和实测值之间不存在显著性差异,可用于该供水系统铁腐蚀预测和出厂水质目标调控。     

调节拉森指数和碳酸钙沉淀势对管网铁释放的影响

拉森指数(LR)和碳酸钙沉淀势(CCPP)是表征管网水质化学稳定性常用的指标,但这两个指标对给水管网铁释放的影响规律和机理目前并不清楚。从实际管网中挖取具有不同通水历史的无内衬铸铁管搭建了4套模拟管网中试装置,以投加不同药剂的方式调节管网进水的LR和CCPP,系统研究了不同水质参数调节方式对管网铁释放行为的影响。结果表明,尽管通过增加硫酸根和氯离子浓度的方式提高LR到同一水平时都会促进管网铁释放,但相同当量的氯离子对铁释放的促进作用明显大于硫酸根。当投加不同药剂提高管网进水的pH值、碱度、钙硬度以达到相同CCPP(17 mg/L)时,管网铁释放表现出较大的差异:投加强碱NaOH改变pH值时,不仅不能有效抑制铁释放反而会有促进作用;投加CaCl_2的方式由于氯离子的引入导致LR升高从而对铁释放有明显的促进作用;投加NaHCO_3、Ca(OH)_2以及Ca(OH)_2和CO_2联用提高CCPP时,由于同时降低了LR,因而对铁释放有明显的抑制作用。研究还发现,钙离子的实际沉淀量与CCPP并不直接相关,而与铁释放速率表现出显著的正相关性。     

不同管网腐蚀与水质稳定性中试研究

通过中试对再生水和饮用水在带水泥内衬的新球墨铸铁管和不带水泥内衬的新球墨铸铁管管网中的腐蚀及水质稳定性进行了研究。8个月中试研究证实:带水泥内衬的球墨铸铁管腐蚀较轻,水质稳定性好,但可能会引起钙离子释放而造成水质硬度增加;不带水泥内衬的球墨铸铁管虽然一开始有一个快速腐蚀阶段,但随着致密氧化层的出现,生物膜上生长出铁氧化菌、铁还原菌和硫酸盐还原菌等细菌,铁还原菌与腐蚀产物之间的相互作用可以加速氧的消耗,有效抑制管网腐蚀,保持管网水质稳定性。     

调节pH值和碱度对给水管网铁释放的控制作用

利用管段模拟反应器,定量分析了调节pH值和调节碱度技术对给水管网铁释放的控制作用。研究发现,提高pH值和增加碱度均可使管网铁释放速率、浊度和色度明显降低。调节pH值从7.6增加至8.2,15 d后管网铁释放速率降低了47%,浊度降低了54%,色度降低了46%;调节碱度从135 mg/L增加至260 mg/L(以CaCO3计),15 d后管网铁释放速率降低了50%,浊度降低了58%,色度降低了52%。对比评价了调节pH值和调节碱度技术的经济性,结果表明:调节出厂水pH值控制管网铁释放的经济成本适宜,可作为突发性管网"黄水"问题的应急控制技术。     

淡化海水并网供水的管网铁释放控制技术研究

淡化海水由于具有较强的侵蚀性,并网供水后会对既有供水管网造成严重的铁释放现象和黄水问题。为了有效地控制管网铁释放,利用管段模拟反应器,定量研究了调节pH值、碱度、硬度和投加缓蚀剂对管网铁释放的控制效果。研究发现,提高pH值、增加碱度和硬度、投加磷酸盐缓蚀剂均可使淡化海水并网供水后造成的管网铁释放量明显降低。由此初步确定了控制淡化海水进入供水管网造成铁过量释放所需满足的水质条件为:管网水的pH值在7.70以上,碱度>80 mg/L,硬度>80 mg/L;必要时可选择投加0.25～0.50 mg/L的聚磷酸盐缓蚀剂。     

某市给水管网铁细菌生长特征调查

给水管网中存在的微生物腐蚀现象会造成管网水水质恶化等一系列问题，因此有必要对给水管网中铁细菌的生长特征进行调查研究。选取某市给水管网，分别采用MPN法和平板计数法对管网水及水厂处理单元出水中铁细菌的数量进行测定。试验结果表明：管网水中的铁细菌含量为0～10^7 CFU／mL，变化范围较大，各处理单元出水中均有铁细菌存在；铁细菌数量与管线长度和温度没有相关性，和余氯值呈明显的负相关；铁细菌数量和管网水中总铁以及溶解性铁含量无明显相关性，但和颗粒性铁含量有一定的相关性。     

管网内淡化水的化学稳定性及控制方法研究

为研究海水反渗透淡化水在管网中的化学稳定性及控制方法,实现减缓管网腐蚀和改善管网水质的目的,分别建立由PE、塑钢和旧铸铁管组成的3套管网,并模拟淡化水在管网中的输配。研究了淡化水在3套管网中的水质变化规律,并考察了投加CaCO3、将淡化水和水库水混合等措施提高淡化水在管网中化学稳定性的效果。综合化学稳定性判别指数LSI(-3.8～-2.2)、RSI(12.3～14.1)、CCPP(-12.5～-10.5 mg/L)可知,反渗透淡化水具有极严重的腐蚀性;PE管网在减缓管网腐蚀和改善管网水质方面优于塑钢管网;投加CaCO3、将淡化水和水库水混合等措施能显著改善淡化水水质。     

Removal of soft deposits from the distribution system improves the drinking water quality

Deterioration in drinking water quality in distribution networks represents a problem in drinking water distribution. These can be an increase in microbial numbers, an elevated concentration of iron or increased turbidity, all of which affect taste, odor and color in the drinking water. We studied if pipe cleaning would improve the drinking water quality in pipelines. Cleaning was arranged by flushing the pipes with compressed air and water. The numbers of bacteria and the concentrations of iron and turbidity in drinking water were highest at 9 p.m., when the water consumption was highest. Soft deposits inside the pipeline were occasionally released to bulk water, increasing the concentrations of iron, bacteria, microbially available organic carbon and phosphorus in drinking water. The cleaning of the pipeline decreased the diurnal variation in drinking water quality. With respect to iron, only short-term positive effects were obtained. However, removing of the nutrient-rich soft deposits did decrease the microbial growth in the distribution system during summer when there were favorable warm temperatures for microbial growth. No Norwalk-like viruses or coliform bacteria were detected in the soft deposits, in contrast to the high numbers of heterotrophic bacteria.     

Iron release from corroded iron pipes in drinking water distribution systems: effect of dissolved oxygen

Iron release from corroded iron pipes is the principal cause of "colored water" problems in drinking water distribution systems. The corrosion scales present in corroded iron pipes restrict the flow of water, and can also deteriorate the water quality. This research was focused on understanding the effect of dissolved oxygen (DO), a key water quality parameter, on iron release from the old corroded iron pipes. Corrosion scales from 70-year-old galvanized iron pipe were characterized as porous deposits of Fe(III) phases (goethite (alpha-FeOOH), magnetite (Fe(3)O(4)), and maghemite (alpha-Fe(2)O(3))) with a shell-like, dense layer near the top of the scales. High concentrations of readily soluble Fe(II) content was present inside the scales. Iron release from these corroded pipes was investigated for both flow and stagnant water conditions. Our studies confirmed that iron was released to bulk water primarily in the ferrous form. When DO was present in water, higher amounts of iron release was observed during stagnation in comparison to flowing water conditions. Additionally, it was found that increasing the DO concentration in water during stagnation reduced the amount of iron release. Our studies substantiate that increasing the concentration of oxidants in water and maintaining flowing conditions can reduce the amount of iron release from corroded iron pipes. Based on our studies, it is proposed that iron is released from corroded iron pipes by dissolution of corrosion scales, and that the microstructure and composition of corrosion scales are important parameters that can influence the amount of iron released from such systems.     

承插式埋地铸铁消防管网的设计与施工

承插式铸铁管道在埋地消防管网中的应用在国内还不太普遍,埋地消防管网具有工作压力高,管网走向多变,安全可靠性能要求高等特点,采用承插式铸铁管道,对设计和施工均提出较高的要求。论文结合中国石油工程建设公司阿尔及利亚某项目消防系统的现场施工情况,介绍整个承插式消防铸铁管网的设计与施工过程,以及整个管网的水压试验情况。     

地理信息系统（GIS）在钢铁企业管理中的应用

针对钢铁企业传统管理方式对企业高速发展的制约进行了分析,介绍了地理信息系统（GIS）及其在钢铁企业中的应用,具体阐述了地理信息系统在钢铁企业的功能需求及其应用给钢铁企业带来的效益,以期解决钢铁企业厂区管线的管理问题。     

Some effects of aqueous silica on the corrosion of iron

Silica is an important natural component of ground and surface waters, and is sometimes added as an inhibitor to control "red water" problems caused by corroding iron pipes. However, the effect of silicates on many aspects of iron corrosion has never been assessed. Experiments with water containing 0.5, 10, 25 or 50mg/L of SiO(2) demonstrated a significant interplay between aqueous silica and iron corrosion. During this 4-month experiment, higher levels of silica caused more iron release to the water and decreased the size of suspended iron particles. The process of iron corrosion also changed aqueous silica concentrations; silica was released into the water from the cast iron during corrosion and was removed from the water by incorporation into the scale layer. Silica also affected the type of scale that formed on the iron coupons. Scale at the lower silica concentrations was fairly uniform and easy to remove from the coupons, while the scale from the high silica reactors was more dense, and was more difficult to remove. Scale from the high concentration silica reactor also developed tall tubercles, and hydrogen gas-containing bubbles were channeled to solution through these tubercles. Iron corrosion occurring via the evolution was significant under all experimental conditions.     

原水铁锰含量对细菌除铁除锰效能的影响

将从水厂成熟锰砂中分离出来的细菌进行驯化和增殖培养,通过改变原水中铁锰含量来改变细菌生长环境,考察了不同条件下混合细菌对铁锰的去除效果.结果表明:在有Fe2+存在的情况下,铁锰氧化细菌维持着正常的活性,对铁锰始终具有高效而稳定的去除能力;Fe2+的存在与否也影响着Mn2+的氧化速率;原水中锰的存在对细菌除铁影响较小.     

Effects of disinfectant and biofilm on the corrosion of cast iron pipes in a reclaimed water distribution system

The effects of disinfection and biofilm on the corrosion of cast iron pipe in a model reclaimed water distribution system were studied using annular reactors (ARs). The corrosion scales formed under different conditions were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM), while the bacterial characteristics of biofilm on the surface were determined using several molecular methods. The corrosion scales from the ARs with chlorine included predominantly α-FeOOH and Fe₂O₃, while CaPO₃(OH)·2H₂O and α-FeOOH were the predominant phases after chloramines replaced chlorine. Studies of the consumption of chlorine and iron release indicated that the formation of dense oxide layers and biofilm inhibited iron corrosion, causing stable lower chlorine decay. It was verified that iron-oxidizing bacteria (IOB) such as Sediminibacterium sp., and iron-reducing bacteria (IRB) such as Shewanella sp., synergistically interacted with the corrosion product to prevent further corrosion. For the ARs without disinfection, α-FeOOH was the predominant phase at the primary stage, while CaCO₃ and α-FeOOH were predominant with increasing time. The mixed corrosion-inducing bacteria, including the IRB Shewanella sp., the IOB Sediminibacterium sp., and the sulfur-oxidizing bacteria (SOB) Limnobacter thioxidans strain, promoted iron corrosion by synergistic interactions in the primary period, while anaerobic IRB became the predominant corrosion bacteria, preventing further corrosion via the formation of protective layers.     

海水淡化水与地表水掺混后的水质稳定性研究

以掺混水的朗格利尔指数作为评价标准,对掺混后的水的化学稳定性进行评价。结果表明,单纯依靠掺混无法满足水质稳定性;用Ca（OH）2对掺混水进行调值,可以增加pH值但不显著影响其他指标,且能部分满足水质的稳定性。在此基础上计算出水源水与海水淡化水在不同季节以不同比例进行掺混并调节pH后的水质稳定性,由于地表水水质随季节发生变化,同样的掺混比例获得的掺混水在某些季节是稳定的,在另一些季节可能存在风险。因此,单纯的掺混不是安全使用海水淡化水的可靠方案。     

硫酸根和碱度变化对管网铁释放的影响

针对水源切换后给水管网中出现的水质超标现象,开展了硫酸根浓度和碱度变化对管垢铁释放的影响研究。利用实验室管段模拟反应器,对比分析了不同硫酸根浓度和碱度对管垢铁释放的影响差异。结果表明,硫酸根浓度增加造成管网水质恶化的响应速度与硫酸根浓度呈正相关,硫酸根浓度越高则响应速度越快。在管垢铁释放的影响因素中,和碱度相比,硫酸根浓度是首要影响因素。在低浓度硫酸根对管垢铁释放无明显影响的情况下,碱度变化对管垢铁释放也基本无影响;而在高浓度硫酸根造成管垢溶解破坏发生铁释放的情况下,随着碱度的降低,铁的释放量明显增加。