《水处理外文翻译》word版.doc

Household Water Treatment in China1 Hong YangGeography and EnvironmentUniversity of SouthamptonUniversity RoadSouthampton SO17 1BJ, United KingdomE-mail: ()2 Jim A. WrightGeography and EnvironmentUniversity of SouthamptonUniversity RoadSouthampton SO17 1BJ, United KingdomE-mail: (j.a.wrightsoton.ac.uk)3 Stephen W. GundryAuthor AffiliationsWater and Health Research CentreUniversity of BristolWoodland RoadBristol BS8 1TH, United KingdomE-mail: (stephen.gundrybristol.ac.uk)This study was supported by the Bill & Melinda Gates Foundation, under grant reference 48599 (Aquatest 2: Delivery a low cost water test for developing countries).Dear Sir:We read with interest the article by Rosa and Clasen about the prevalence of household water treatment in low-income and middle-income countries. They discussed the geographic limitations of their global estimation, especially the lack of data for the largest national population in China. Several surveys covering water and sanitation have been undertaken in China in recent decades, such as the World Health Survey, the Global Water Supply and Sanitation Assessment 2000, and the Multiple Indicator Cluster Survey. These survey results have already been included in the World Health Organization/United Nations Childrens Fund Joint Monitoring Program report. However, none of these survey questionnaires covered household water treatment. Despite the lack of data on home water treatment accessible in the English language, it is possible that other surveys exist that have been conducted by the Chinese government rather than through international systems, such as the Multiple Indicator Cluster Survey, with results published in Chinese only.We searched the bibliographic database Chinese National Knowledge Infrastructure by using the Chinese key words for “household” and “water” and “treatment/disinfection”. We found 417 Chinese language references. After screening the titles and abstracts of all references and the content of an additional 197 references, we found one paper reporting the national summary results of the Investigation of Drinking Water and Sanitation in the Rural Areas conducted jointly by the Ministry of Health and the National Committee for Patriotic Public Health Campaign, Peoples Republic of China, during August 2006November 2007.In this nationally representative multi-stage cluster survey of rural areas, 6,948 sites were surveyed in 6,590 villages across all 31 provinces, autonomous regions, and municipalities in mainland China. A total of 65,839 households were interviewed and 6,948 supply system, groundwater and surface water samples were tested for physicochemical parameters and total coliforms. The interviews included two questions on home water treatment: “What is your usual drinking practice? 1) Drink raw water, 2) Drink boiled water” and “Do you treat (other than boiling) the household?s water? Yes or No”.Although the raw data are still not publicly available, the summary of the official report indicated that 85.23% of rural households boiled their water before drinking and 5.11% treated their water (excluding boiling). Given that the mainland Chinese rural population was estimated to be 712.88 million in 2009,this finding suggests that the population boiling household water is 607.59 million and the population using other forms of home water treatment is 36.3 million in rural China. Household water filters are increasingly used in urban areas of China. Although there are no reported household survey data for urban areas, one report estimated that 35% of the urban population used household water filters.If this 4% prevalence estimate for household water filtration is applied to the total mainland Chinese urban population of 621.86 million,this suggests a population of 24.9 million filtering their water. Including these estimates for China, the global population from low-income and middle-income countries boiling household water doubles from 0.601 to 1.21 billion, and the population using treated household water increases to at least 1.78 billion.A small-scale survey in Anhui Province in central China that collected 35 household storage water samples from randomly selected households in three counties reported that the compliance rate for total coliforms ( 1 colony-forming unit/100 mL) of water stored in the home was only 39%.This limited evidence on microbial contamination of stored water implies that there may be a need for household water treatment in rural China. Other treatment methods, e.g., filters, are increasingly used in more economically developed parts of rural China.However, boiling is still the most widely used water treatment method in rural China. The Investigation of Drinking Water and Sanitation in the Rural Areas survey figures illustrate the need for more data on the worlds most populous nation in understanding global patterns of household water treatment. It further underscores the need articulated by Rosa and Clasen to understand the effectiveness and use of boiling in non-intervention settings.中国家庭水处理1杨宏地理和环境南安普顿大学大学路南安普顿SO17 1 bj、英国电子邮件:)2吉姆a赖特地理和环境南安普顿大学大学路南安普顿SO17 1 bj、英国电子邮件:(j.a.wrightsoton.ac.uk)3 Gundry stephen w .+作者从属关系水和卫生研究中心布里斯托大学林地道路布里斯托尔BS8 1、英国电子邮件:(stephen.gundrybristol.ac.uk)这项研究由比尔和梅林达盖茨基金会,在格兰特参考48599(Aquatest 2:交付一个低成本水试验对于发展中国家)。亲爱的先生:我们读这篇文章有兴趣通过罗莎和Clasen关于普遍的家庭水处理在低收入和中等收入国家。他们讨论了地理限制的全球评估,特别是缺乏数据在中国最大的国家人口。几个调查,覆盖水和卫生设施先后在中国在最近几十年,如世界健康调查,全球供水和卫生评估2000年,和多指标组群调查。这些调查结果已经被包括在世界卫生组织/联合国儿童基金会联合监测项目报告。然而,这些调查问卷涵盖家庭水处理。尽管缺乏家庭水处理可访问的数据在英语语言,可能存在其他调查,进行了由中国政府而不是通过国际系统,如多个指标,结果发表调查中只有中文。我们找遍了整个中国国家知识基础设施的书目数据库使用中国关键字为“家庭”和“水”和“治疗/消毒”。我们发现417中文参考文献。筛选后的标题和摘要的内容的所有引用和一个额外的197引用,我们发现一纸报告全国调查汇总结果的饮用水和卫生设施在农村地区进行了由卫生部和全国爱国卫生运动委员会、中华人民共和国在2006年8月- 11月2007.3在这个全国代表性的农村地区多阶段整群调查,6948网站在6590年调查村庄所有31个省、自治区、直辖市在中国大陆。共有65839户家庭接受了采访,6948年供应系统、地下水和地表水水样为物理化学参数和总大肠菌群。面试包括两个问题在家庭水处理:“你平常喝实践?1)喝生水,2)喝开水”和“你治疗(沸腾)家庭吗?年代的水吗?是的或没有”。尽管原始数据仍然没有公开可用的,总结的官方报告显示,85.23%的农村家庭煮水喝,治疗前5.11%他们的水(不含沸腾)。鉴于中国大陆农村人口大约在7.1288亿2009年,这个发现表明,人口是6.0759亿,家庭用水煮沸的人口使用其他形式的家庭水处理是3630万在中国农村。家庭水过滤器中,越来越多地使用在城市地区的中国。虽然没有报道家庭调查数据为城市地区,一份报告估计,3 - 5%的城市人口使用家庭水过滤器。如果这4%患病率估计家庭水过滤应用于总中国大陆城市人口6.2186亿,这表明2490万人口的过滤水。包括这些估计对中国而言,全球人口从低收入和中等收入国家沸腾家庭水双打从0.601到12.1亿年,人口使用家庭水处理增加到至少17.8亿。一个小规模的调查在安徽省,收集了35个家庭存储水样本中随机选择的家庭在三个县报道,合规率对总大肠杆菌群(10 years. Chemicals are not required for this process except during periodic cleaning of membranes and pre-coagulation (used to enhance contaminants removal).2.4 Reverse osmosis and nanofiltrationRO and NF are pressure-driven membrane processes. Osmotic pressure of the feed solution is suppressed by applying hydraulic pressure which forces permeate (clean water) to diffuse through a dense, non-porous membrane . Seawater RO can remove contaminants as small as 0.0001 m, but its major disadvantage is membrane fouling and scaling . Early studies on using RO to treat produced water failed due to insufficient process integration and poor treatment . Nicolaisen and Lien however reported a successful RO treatment of oilfield produced water in Bakersfield, California. The pilot system which was operated for over 1700 h in 6 months produced 20 gpm of clean water. Bench-scale studies have shown the potential of brackish water RO membranes to successfully treat oil and gas produced water. Experiments indicated that RO membrane technology would be excellent for oilfield produced water treatment with appropriate pre-treatment technology . Capital costs of RO membrane systems vary depending on the size of rejection required, materials of construction and site location. Operating costs depend on energy price and total dissolved solid (TDS) level in the feed water. RO membrane systems generally have a life expectancy of 37 years. NF is a robust technology for water softening and metals removal and is designed to remove contaminants as small as 0.001 m. It is applicable for treating water containing TDS in the range of 50025 000 ppm. This technology is similar to RO. NF membranes were employed for produced water treatment on both bench and pilot scales. Mondal and Wickramasinghe studied the effectiveness of NF membranes for the treatment of oilfield produced water. Results showed a minimal improvement when compared with the effectiveness of brackish water RO treatment of the same feed water. 2.5 Thermal technologiesThermal treatment technologies of water are employed in regions where the cost of energy is relatively cheap. Thermal separation process was the technology of choice for water desalination before the development of membrane technology. Multistage flash (MSF) distillation, vapour compression distillation (VCD) and multieffect distillation (MED) are the major thermal desalination technologies . Hybrid thermal desalination plants, such as MEDVCD, have been used to achieve higher efficiency . Although membrane technologies are typically preferred to thermal technologies, recent innovations in thermal process engineering make thermal process more attractive and competitive in treating highly contaminated water. 2.6 Multistage flashMSF distillation process is a mature and robust technology for brackish and sea water desalination. Its operation is based on evaporation of water by reducing the pressure instead of raising the temperature. Feed water is pre-heated and flows into a chamber with lower pressure where it immediately flashes into steam. Water recovery from MSF treatment is 20% and often requires post-treatment because it typically contains 210 mg/l of TDS. A major setback in operating MSF is scale formation on heat transfer surfaces which often makes this process require the use of scale inhibitors and acids. Overall costs vary depending on the size, site location and materials of construction . Its energy requirement is between 3.35 and 4.70 kWh. Globally, MSF market share has significantly decreased due to competition of membrane technologies, but it is a relatively cost-effective treatment method with plant life expectancy of more than 20 years, and can be employed for produced water treatment . 2.7 Multieffect distillationMED process involves application of sufficient energy that converts saline water to steam, which is condensed and recovered as pure water. Multiple effects are employed in order to improve the efficiency and minimize energy consumption . A major advantage of this system is the energy efficiency gained through the combination of several evaporator systems. Product water recovery from MED systems are in the range of 2067% depending on the type of the evaporator design employed . Despite the high water recovery from MED systems, it has not been extensively used for water production like MSF because of scaling problem associated with old designs. Recently, falling film evaporators have been introduced to improve heat transfer rates and reduce the rate of scale formation . MED has a life cycle of 20 years and can be applied to a wide range of feed water quality like MSF. It is good for high TDS produced water treatment . Scale inhibitors and acids may be required to prevent scaling and pH con