Significance of losses in water distribution systems in India

Effective management of water supply systems consists in supplying adequate quantities of clean water to the population. Detailed pilot studies of water distribution systems were carried out in 9 cities in India during 1971-81 to establish the feasibility of a programme of assessment, detection, and control of water losses from supply systems. A cost-benefit analysis was carried out. Water losses from mains and service pipes in the areas studied amounted to 20-35% of the total flow in the system. At a conservative estimate, the national loss of processed water through leaks in the water distribution systems amounts to 10¹² litres per year, which is equivalent to 500 million rupees.     

60起管网及二次供水污染事故分析

了解管网及二次供水污染事故的发生特点和原因。搜集国内近20年来的管网及二次供水污染事故案例，管网及二次供水污染以生物性污染为主，占73．3％，除居民小区和企事业单位外，学校和单位家属区是重要的污染事故发生地，发生率均占11．7％，污染环节以自来水管网和高低蓄水池为主，占51．7％和43．3％，污染原因主要是管网及二次供水设施出现渗漏或破裂，污水倒灌，设施与污水管相连引起负压虹吸现象，设施卫生防护差而受到污水污物的污染。     

试验给水管网不同给水管材腐蚀的电镜分析及细菌API鉴定

目的研究不同给水管材的腐蚀、结垢及饮用水与生物膜中的菌种情况。方法以实验室模拟给水管网为研究对象,应用环境扫描电镜对目前给水管网中使用较为普遍的镀锌管、PPR管(无规共聚聚丙烯管)和ABS(苯乙烯管)管的腐蚀、结垢情况及结垢层元素组成进行了分析;应用生物梅里埃API(Analytic products NC)细菌鉴定系统10S和20E对饮用水及生物膜中常见的菌种进行了鉴定,并分析了菌种致病性。结果镀锌管的腐蚀、结垢情况最为严重,PPR和ABS管内壁存在薄结垢层。API10S试剂条鉴定实验给水管网水样的10株菌中有7株为条件致病菌;API20E试剂条鉴定水样及生物膜样品的21株菌中5株为致病菌,11株为条件致病菌,其余5株对人体尚无致病报道。结论饮用水管网微生物学水质较差,水及生物膜样品中大多数细菌都为条件致病菌,存在一定的微生物风险。在给水管材方面应加快城市旧管网改造步伐,推广应用新型管材。     

Optimal reconstruction of historical water supply to a distribution system: A. Methodology

The New Jersey Department of Health and Senior Services (NJDHSS), with support from the Agency for Toxic Substances and Disease Registry (ATSDR) conducted an epidemiological study of childhood leukaemia and nervous system cancers that occurred in the period 1979 through 1996 in Dover Township, Ocean County, New Jersey. The epidemiological study explored a wide variety of possible risk factors, including environmental exposures. ATSDR and NJDHSS determined that completed human exposure pathways to groundwater contaminants occurred in the past through private and community water supplies (i.e. the water distribution system serving the area). To investigate this exposure, a model of the water distribution system was developed and calibrated through an extensive field investigation. The components of this water distribution system, such as number of pipes, number of tanks, and number of supply wells in the network, changed significantly over a 35-year period (1962--1996), the time frame established for the epidemiological study. Data on the historical management of this system was limited. Thus, it was necessary to investigate alternative ways to reconstruct the operation of the system and test the sensitivity of the system to various alternative operations. Manual reconstruction of the historical water supply to the system in order to provide this sensitivity analysis was time-consuming and labour intensive, given the complexity of the system and the time constraints imposed on the study. To address these issues, the problem was formulated as an optimization problem, where it was assumed that the water distribution system was operated in an optimum manner at all times to satisfy the constraints in the system. The solution to the optimization problem provided the historical water supply strategy in a consistent manner for each month of the study period. The non-uniqueness of the selected historical water supply strategy was addressed by the formulation of a second model, which was based on the first solution. Numerous other sensitivity analyses were also conducted using these two models. Both models are solved using a two-stage progressive optimality algorithm along with genetic algorithms (GAs) and the EPANET2 water distribution network solver. This process reduced the required solution time and generated a historically consistent water supply strategy for the water distribution system.     

上海市青浦区居民饮用水氟暴露评估

【目的】通过上海市青浦区饮用水中氟的监测以评估居民通过饮用水摄入氟的外暴露,为持续改善区域内饮用水水质、提高居民健康水平提供数据支持。【方法】2016—2021年每月在上海市青浦区42个监测点采集管网水,用离子色谱法检测管网水中氟含量,评价饮用水质状况。【结果】2016—2021年青浦区饮用水中氟含量波动范围为0.10～0.96 mg·L^-1。青浦区饮用水中氟无超标,低于WHO建议范围的下限。青草沙水源供水区域饮用水中氟含量中位数为0.20 mg·L^-1,淀山湖水系水源供水区域饮用水中氟含量中位数为0.44 mg·L^-1,且两者的差异有统计学意义(Z=20.260,P<0.001)。饮用水中氟含量在时间上有逐年降低的趋势,尤其是淀山湖水系水源供水区域降低尤为明显,氟平均水平由2017年的0.60 mg·L^-1,逐渐降低到2021年0.36 mg·L^-1;青草沙水源供水区域饮用水中氟含量降低较为平缓,由2017年的0.25 mg·L^-1,逐渐降低至0....     

野战医用水处理和供应系统的研究

目的：研究一套完整的野战水处理和供应系统,以满足抢险救灾、野外推演训练时医疗用水的需求。方法：完整的野战水处理和供应系统可以分为水处理和供水两部分。水处理部分采用滤过、沉淀、消毒、吸附以及离子调节等手段,使得从水源汲取的原始水达到生活和医疗用水的水质;供水部分通过增压、缓冲、稳流等技术,配合各种转接灵便的管路、阀门和快速接头．组成高效的供水管网。结果：研制的野战水处理和供应系统,具有供水水质有保证、水量充足、水流稳定、水压符合要求、系统运行安全可靠、故障率低、节省能耗等优点,满足了野战医疗用水需要。结论：通过系统的合理设计和优化．证实便携、低能耗的野战水处理和供应系统的研究完全可行,系统的实施为提高野战医疗的应急救治、机动灵活能力提供了保证。     

Assessment of slow sand filtration system for rural water supply schemes--a case study

In India, water supply programmes form a part of National Development Plans and are implemented in a phased manner under the Five-Year Plans. A number of departments and ministries of the Central and State Governments have been vested with the responsibility for water supply and sanitation. Due to inherent advantages of slow sand filters over conventional rapid sand filters, the Panchayat Raj Engineering Department (PRED), Government of Andhra Pradesh has designed and constructed a number of slow sand filter plants for rural water supply schemes in the state. At the instance of Netherland Assisted Project (NAP) Office, Hyderabad, NEERI undertook a critical evaluation of the functioning of three slow sand filter plants in Andhra Pradesh and suggested improvements in construction, operation and maintenance (O&M) including a review of design criteria followed by PRED. The paper presents the outcome of these studies along with suggestions needed to bring about improvements in source protection, design, construction, O&M of slow sand filter and training programme to improve the quality of supervision.     

浦东新区居住小区分质供水现状及其水质控制措施研究

目的掌握我区居住小区分质供水的管理现状及其水质状况，调查可能对水质造成影响的各种因素，研究控制措施，为有关部门制订相应的标准进行有效监管提供科学依据。方法于2005--2006年间夏季、秋季和冬季分三次对全区12个分质供水居住小区进行调查和采样。结果调查的12个居住小区的分质供水项目，其功能布局、卫生设施、水处理流程以及卫生管理方面都或多或少存在着问题。统计表明：分质供水水质受到了二次污染，而分质供水实际使用率和回水返流位置是影响分质供水水质的重要因素。结论文章对分质供水场地要求、管理规范进行了探讨，并提出应尽快制订和出台管道分质供水的卫生规范和嘈理要求，规范和约束对分质供水的建设和管理行为，使卫生行政部门对其的监管能有据可依。同时文章还提出在水处理工艺流程设计上管网回水须返流入中间水箱，同时在铺设供水管道时在立管和入户管间增设阀门开关，对未开通使用分质供水的住户和空置房关闭阀门，减少管网盲端“死水”；并建议设置备用成品水箱，且成品水箱的蓄水量不宜过大，要充分考虑小区入住率及入住用户分质供水使用率，减少水在储水设备中停留的时间等。     

Modelling supply and demand influences on the use of health care: implications for deriving a needs-based capitation formula

Many health-care systems allocate funding according to measures of need. The utilisation approach for measuring need rests on the assumptions that use of health care is determined by demand and supply and that need is an important element of demand. By estimating utilisation models which allow for supply it is possible to isolate the socio-economic and health characteristics which affect demand. A subset of these variables can then be identified by a combination of judgement and further analysis as needs variables to inform funding allocations. We estimate utilisation models using newly assembled data on admissions to acute hospitals, measures of supply, morbidity and socio-economic characteristics for 8414 small geographical areas in England. We make a number of methodological innovations including deriving additional measures of specific morbidities at small area level from individual level survey data. We compare models with different specifications for the effect of waiting times and provider characteristics, with total, planned and unplanned hospital admissions, and estimated at small area (ward) and primary care organisation (general practice) level. After allowing for waiting times, distance, capacity and the availability of private health care, measures of mortality, self-reported morbidity, low education and low income increase the use of health care. We find evidence of horizontal inequity with respect to ethnicity and employment and suggest a method for reducing its effects when deriving a needs-based allocation formula.     

Disinfection of water distribution systems for legionella: a review of application procedures and methodologies

Hospital-acquired legionella pneumonia is emerging as a major problem; potable water distribution systems have been shown to be the primary reservoirs for the legionella organisms. As a result, disinfection measures have been developed to eradicate the organism from the hospital water supply. Each disinfection modality differs in its design and application such that choosing an appropriate cost-effective control measure requires careful analysis and planning. We assess in comparative fashion the disinfection modalities of thermal eradication ("heat-and-flush"), instantaneous steam-heating system, chlorination, ultraviolet light irradiation, ozonation and metal ionization. The theoretical bases, the actual procedure or system, the logistics of implementation, the costs and personnel requirements and the advantages and disadvantages are presented for each modality. Criteria for selection of a method, the use of combinations of methods, parameters for installation, pitfalls in implementation and a plan for subsequent environmental surveillance are discussed in detail.     

Estimates of microbial quality and concentration of copper in distributed drinking water are highly dependent on sampling strategy

The numbers of bacteria generally increase in distributed water. Often household pipelines or water fittings (e.g., taps) represent the most critical location for microbial growth in water distribution systems. According to the European Union drinking water directive, there should not be abnormal changes in the colony counts in water. We used a pilot distribution system to study the effects of water stagnation on drinking water microbial quality, concentration of copper and formation of biofilms with two commonly used pipeline materials in households; copper and plastic (polyethylene). Water stagnation for more than 4 h significantly increased both the copper concentration and the number of bacteria in water. Heterotrophic plate counts were six times higher in PE pipes and ten times higher in copper pipes after 16 h of stagnation than after only 40 min stagnation. The increase in the heterotrophic plate counts was linear with time in both copper and plastic pipelines. In the distribution system, bacteria originated mainly from biofilms, because in laboratory tests with water, there was only minor growth of bacteria after 16 h stagnation. Our study indicates that water stagnation in the distribution system clearly affects microbial numbers and the concentration of copper in water, and should be considered when planning the sampling strategy for drinking water quality control in distribution systems.     

以山涧溪流为水源的农村饮水安全工程卫生学评价

目的对一座以山涧溪流为水源的农村饮水安全工程开展卫生学评价。方法通过问卷调查、现场卫生学调查、水源卫生学评价、工程综合卫生学评价、水质检测及评价、专家会商等程序,评估该饮水工程供水流程中存在的卫生学风险并提出改进建议。结果该工程水源水量充足、水质良好,但未严格落实水源卫生防护措施;所采取的水处理工艺能基本实现水质净化效果,水质基本达标。但滤池反冲洗系统设计不合理,消毒设备的管理与使用不规范,生产节点未制定量化指标;水厂化验室检测项目未达到要求。结论本饮水工程水质基本能达到饮水安全要求,存在水源污染、水质浊度超标风险,自身检测能力不足、管理不够细化等问题,暂未发现重金属污染风险。建议做好以下工作:加强水源保护与监测,避免重金属污染;优化水质净化工艺;加强输配水管网巡查、更新;加强自主检测能力建设。     

基于GM（1,1）模型的广东省儿科医生数量缺口预测

目的 预测2021—2025年广东省儿科医生的缺口数量,为构建规模适宜的儿科医生队伍提供决策依据。方法 采用年均增长率描述广东省2012—2020年儿科医生的实际数、需求数和缺口数;运用GM（1,1）模型分别预测2021—2025年广东省儿科医生的实际数和需求数,求得同期儿科医生供需比及缺口数。结果 广东省儿科医生日均负担诊疗人次从2012年的20.84人降至2019年的20.16人,但2012—2020年全省儿科医生日均工作负荷均高于同期全省医生和全国儿科医生;2012—2020年广东儿科医生实际数、需求数和缺口数的年均增长率分别为6.63％、5.29％、1.39％,儿科医生供需比均小于1;预测结果显示,2021—2025年广东省儿科医生实际数继续保持较快增长,但儿科医生供需比仍然小于1,儿科医生缺口数逐年扩大。结论 广东省儿科医生工作负担重强度高,儿科医生供给未能满足实际需求;建议加快儿科医生全方位多层次人才培养,进一步细化儿童医疗服务支持政策以稳定儿科医生队伍;落实健康中国行动,提高儿童青少年身体素质。     

上海市二次供水卫生监督监测结果分析

  目的  了解市区内二次供水设施状况和水质卫生现况,为政府有针对性地采取措施保障饮用水卫生安全提供科学依据。  方法  对辽宁省锦州市市辖区267家二次供水单位进行卫生监督检查,并对末梢水进行快速检测,分析影响水质的危险因素。  结果  267家二次供水单位中水质合格单位229家,水质合格率为85.8 %;1998年之前建设的二次供水设施水质合格率（79.1 %）明显低于1998年之后建设的二次供水设施水质合格率（94.1 %）（χ² = 12.262,P < 0.05）,多因素logistic回归分析结果显示,建设年代（OR = 6.106）、泵房内墙壁或顶棚无防霉措施（OR = 3.749）、管道锈迹严重（OR = 23.014）、生活用水和消防共用一个贮水设备（OR = 3.880）、未办理卫生许可证（OR = 5.723）是二次供水水质的影响因素（P < 0.05）。  结论  锦州市市辖区二次供水水质合格率还有待进一步提高;政府及供水单位应加大对二次供水设施的卫生监督及整改力度,消除影响二次供水水质的危险因素,排除隐患,保障百姓饮水卫生安全。     

HACCP在大汶河流域小型供水系统及水质检测中的应用

[目的]探讨危害分析和关键控制点(HACCP)在大汶河流域小型供水系统、用户及卫生检测机构应用的可行性,以便有针对性地制定具体的控制和管理措施。[方法]2011年,将HACCP的原理和方法应用于泰安市辖区内大汶河流域小型供水系统、用户及卫生检测等流程,并对执行控制措施的效果进行评价。[结果]确定了水源水井周围环境及水质消毒,输水管道的材质、深度及位置,用户的家庭生活环境及盛水器具,样品采集方式、运送时间及措施、检验操作过程、实验器材及无菌环境是影响农村小型集中供水水质的关键控制点,制定并实施控制和管理措施。实施1年后与实施前比较,饮用水的硝酸盐等理化指标合格率变化不明显(P>0.05),细菌总数、总大肠菌群、耐热大肠菌群合格率明显上升(P<0.01)。[结论]在大汶河流域小型供水系统、用户及卫生检测机构中应用HACCP可明显提高供水的微生物指标合格率。     

农村供水系统中应用危害分析和关键控制点原理的实例研究

目的探讨危害分析和关键控制点(HACCP)在农村供水系统中应用的可行性及效果。方法选择河北省丰宁满族自治县土城供水系统作为研究现场,参照WHOFAO食品法典委员会发布的《HACCP及其应用准则》和WHO的《饮水水质指南》进行危害分析和评价,并在此基础上寻找危害控制措施。结果农村供水系统中影响供水安全的关键控制点分布在从水源到用户的各个环节。采取控制措施,各供水环节的硝酸盐含量显著下降,其余水质指标在HACCP前后无显著性差异。供管水人员的业务水平平均分由75.2提高到86.6,前后有显著性差异。结论HACCP作为一种危害管理机制,应用于农村供水系统的水质管理是可行的。     

硬聚氯乙烯管材对自来水水质影响调查

目的 探讨硬聚氯乙烯（PVC－U）管材对自来水水质的影响。方法 对某PVC－U管材进行安全性评价，并对使用该管材的住宅小区的2个户外进水口和4个户内出水口水样的感官性状，一般化学指标，重金属，有机物指标，放射性指标进行检测及及进行毒理学试验。结果 该PVC－U管材浸泡水除Fe超标外，其余指标均达标。进水口与出水口水样各指标差异无显著性，出水口水样急性经口毒性试验，30天喂养试验，微核试验，Ames试验均阴性。结论 PVC－U管材是安全卫生的供水管材。     

Waterborne diseases prevention: evaluation of inspection scoring system for water sites according to water microbiological tests during the Athens 2004 pre-Olympic and Olympic period

STUDY OBJECTIVES: To evaluate the inspection grading system for water sites implemented during the Athens 2004 Olympic inspection programme. DESIGN: The relation between the standardised inspections results of 716 water supply systems and 289 public swimming pools, and microbiological test results of 2358 samples collected during inspections was examined. SETTING: Athens, Thessaloniki, Patra, Volos, and Iraklio, Greece. Inspections and sampling conducted during a two year period before the 2004 Olympics. MAIN RESULTS: Swimming pools unsatisfactory inspection grading results were significantly associated with positive water microbiological test results (relative risk = 2.5, p<0.05). One of the six violations of swimming pools and five of the seven violations of water supply systems designated as "critical" water safety hazards in the inspection reports were significantly associated with positive microbiological test results. The receiver operating characteristic analysis identified the unsatisfactory score designed in the swimming pools standardised inspection report, as the ideal score (-15), in adequately producing positive microbiological test results (sensitivity 13.2%, specificity 89%). CONCLUSIONS: This study shows the utility of standardised inspection grading systems in waterborne diseases prevention planning and implementation strategies of policy makers and regulators. Future water quality assessment should be based on the implementation of a robust standardised inspection system and reduce the need of microbiological tests.     

Drug policy in China: pharmaceutical distribution in rural areas

In 1978, China decided to reform its economy and since then has gradually opened up to the world. The economy has grown rapidly at an average of 9.8% per year from 1978 to 1994. Medical expenditure, especially for drugs, has grown even more rapidly. The increase in medical expenditure can be attributed to changing disease patterns, a higher proportion of older people in the population and fee-for-service incentives for hospitals. Due to the changing economic system and higher cost of health care, the Chinese government has reformed its health care system, including its health and drug policy. The drug policy reform has led to more comprehensive policy elements, including registration, production, distribution, utilization and administration. As a part of drug policy reform, the drug distribution network has also been changed, from a centrally controlled supply system (push system) to a market-oriented demand system (pull system). Hospitals can now purchase drugs directly from drug companies, factories and retailers, leading to increased price competition. Patients have easier access to drugs as more drugs are available on the market. At the same time, this has also entailed negative effects. The old drug administrative system is not suitable for the new drug distribution network. It is easy for people to get drugs on the market and this can lead to overuse and misuse. Marketing factors have influenced drug distribution so strongly that there is a risk of fake or low quality drugs being distributed. The government has taken some measures to fight these negative effects. This paper describes the drug policy reform in China, particularly the distribution of drugs to health care facilities.     

2009年徐州市区二次供水卫生状况调查

[目的]了解徐州市区二次供水卫生状况。[方法]按照《江苏省2009年生活饮用水卫生重点监督检查工作实施方案》,使用全省统一的调查表和统计方法,对市区二次供水单位全面调查。[结果]市区共约450个蓄水式二次供水单位,其中,二次供水细菌指标平均合格率为90.29%,化学指标平均合格率为97.57%。3.20%的蓄水池管理责任单位不明晰,清洗消毒等管理制度不健全。18.84%的二次供水单位未能保证蓄水池每年清洗1次。[结论]二次供水水质合格率有了明显提高。设计不合理的蓄水池和管理疏漏仍然是影响二次供水水质的主要因素。应当加强卫生监督,采取综合措施,保障二次供水卫生安全。