海水淡化在加利福尼亚州

海水淡化在加利福尼亚州 CHAPTER ONE: BACKGROUND第一章： 背景 Desalination Plants Worldwide海水淡化厂世界范围 Desalination Technologies海水淡化技术 o Reverse Osmosis (RO)反渗透（反渗透） o Distillation蒸馏 Input Water (Feedwater)投入水（给水） Product Water生产用水 Product Water Recovery产品水回收 Pretreatment Processes预处理过程 Filter Backwashing, Membrane Cleaning and Storage, Scaling Prevention and Removal, and Pipeline Cleaning过滤器反冲洗，膜的清洗和存放，防结垢和移除，以及管道清洗 Waste Discharges废污水排放 Energy Use能源使用 Comparison of Distillation and Reverse Osmosis Technologies比较蒸馏和反渗透技术 Costs of Desalinated Water成本的淡化水 Costs of Other Water Sources成本的其他水源 Desalination Plants Worldwide海水淡化厂世界范围 Of the more than 7,500 desalination plants in operation worldwide, 60% are located in the Middle East.对超过7500名的海水淡化厂在世界各地运行， 60 是位于中东地区。 The worlds largest plant in Saudi Arabia produces 128 MGD of desalted water.世界上最大的核电厂在沙特阿拉伯生产128 mgd的脱盐水。 In contrast, 12% of the worlds capacity is produced in the Americas, with most of the plants located in the Caribbean and Florida.相比之下， 12 的世界的能力，是产于美洲，而且大部份的工厂位于加勒比海和佛罗里达州。 To date, only a limited number of desalination plants have been built along the California coast, primarily because the cost of desalination is generally higher than the costs of other water supply alternatives available in California (eg, water transfers and groundwater pumping).迄今为止，只有有限数量的海水淡化厂已建成沿加州海岸，这主要是因为海水化淡的成本普遍高于成本的其他供水办法可在加利福尼亚州（例如，水资源转移和地下水抽水） 。 However, as drought conditions occur and concern over water availability increases, desalination projects are being proposed at numerous locations in the state.然而，由于干旱条件下发生和关注水的供应增加，海水淡化项目正在拟议在许多地点设在国家。 Desalination Technologies海水淡化技术 Desalination is a process that removes dissolved minerals (including but not limited to salt) from seawater, brackish water, or treated wastewater.海水淡化是一个过程，可去除溶解矿物质（包括但不限于盐） ，从海水，半咸水或处理过的废水。 A number of technologies have been developed for desalination, including reverse osmosis (RO), distillation, electrodialysis, and vacuum freezing.一些技术已经开发出来，用于海水淡化，包括反渗透（反渗透） ，蒸馏法，电渗析法，真空冷冻。 Two of these technologies, RO and distillation, are being considered by municipalities, water districts, and private companies for development of seawater desalination in California.两个这些技术，反渗透法和蒸馏，警方现正考虑由直辖市，水区，而私人公司，为发展海水淡化技术在加利福尼亚州。 These methods are described below.这些方法介绍如下。 Reverse Osmosis (RO) 反渗透（反渗透） In RO, feedwater is pumped at high pressure through permeable membranes, separating salts from the water (Figure 1).在反渗透，给水泵在高压下，通过渗透膜，分离盐从水（图1 ） 。 The feedwater is pretreated to remove particles that would clog the membranes.给水预处理，以消除粒子，将阻塞膜。 The quality of the water produced depends on the pressure, the concentration of salts in the feedwater, and the salt permeation constant of the membranes.水的质量产生了依赖于压力，浓度盐在给水和盐渗透常数膜。 Product water quality can be improved by adding a second pass of membranes, whereby product water from the first pass is fed to the second pass.产品水质得以改善，增加了第二个通过的膜，即产品的防水，从第一通是美联储第二次通过。 Figure 1. Flow Diagram of a reverse osmosis system (courtesy of USAID). 图1 。流程图一个反渗透系统（礼貌美国国际开发署） 。 (Kahn, 1986.) （卡恩， 1986 ） 。 Distillation 蒸馏 In the distillation process, feedwater is heated and then evaporated to separate out dissolved minerals.在蒸馏过程中，给水加热，然后蒸发分离出来，溶解矿物质。 The most common methods of distillation include multistage flash (MSF), multiple effect distillation (MED), and vapor compression (VC) (Figure 2).最常见的方法包括蒸馏多级闪光（无国界医生组织） ，多效蒸馏（ MED ） ，以及蒸汽压缩（ VC ）的（图2 ） 。 Figure 2. Common methods of distillation. 图2 。常用方法蒸馏。 In MSF, the feedwater is heated and the pressure is lowered, so the water flashes into steam.在无国界医生组织，给水加热和压力降低，所以水闪亮变成蒸汽。 This process constitutes one stage of a number of stages in series, each of which is at a lower pressure.这个过程构成了一个阶段一个阶段的数目在系列，其中每正处在一个较低的压力。 In MED, the feedwater passes through a number of evaporators in series.在地中海，给水通过多项蒸发器系列。 Vapor from one series is subsequently used to evaporate water in the next series.蒸气从一个系列是后来用于蒸发水，在未来系列。 The VC process involves evaporating the feedwater, compressing the vapor, then using the heated compressed vapor as a heat source to evaporate additional feedwater.风险投资过程中涉及到蒸发了给水，压缩蒸气，然后用加热压缩蒸气作为热源蒸发增加给水。 Some distillation plants are a hybrid of more than one desalination technologies.有些蒸馏厂，是一种混合的一个以上的海水淡化技术。 The waste product from these processes is a solution with high salt concentration.垃圾产品，从这些过程是最佳的解决方案与高盐的浓度。 Input Water (Feedwater)投入水（给水） Desalination plants may use seawater (directly from the ocean through offshore intakes and pipelines, or from wells located on the beach or seafloor), brackish groundwater, or reclaimed water as feedwater.海水淡化厂可利用海水（直接从印度洋经离岸金融摄入量和管道，或从水井坐落于海滩或海底） ，含盐地下水，或再生水作为给水。 Since brackish water has a lower salt concentration, the cost of desalting brackish water is generally less than the cost of desalting seawater.由于微咸水具有较低的盐分浓度，所花费用的脱盐苦咸水处理普遍低于生产成本的淡化海水。 Intake pipes for desalination plants should be located away from sewage treatment plant outfalls to prevent intake of discharged effluent.进水口管道海水淡化厂应设在远离污水处理厂排污渠，以防止摄入出院污水。 If sewage treatment discharges or other types of pollutants are included in the intake, however, the pre- and post-treatment processes should remove the pollutants.如果污水处理厂的排放物或其他种类的污染物，都包括在入伙事宜，不过，会前和会后的处理过程，应该消除污染物的影响。 Product Water生产用水 Distillation plants produce a high-quality product water that ranges from 1.0 to 50 ppm tds, while RO plants produce a product water that ranges from 10 to 500 ppm tds.蒸馏厂生产高品质的产品水范围从1.0至50 ppm的全港发展策略，而反渗透厂生产的产品水范围从10到500 ppm的全港发展策略。 (The recommended California drinking water standard for maximum tds is 500 mg/L, which is equivalent to 500 ppm.) In desalination plants that produce water for domestic use, post-treatment processes are often employed to ensure that product water meets the health standards for drinking water as well as recommended aesthetic and anti-corrosive standards. （推荐加州饮用水标准为最高，全港发展策略是500毫克/升，相当于500百万分之一） 。海水淡化厂所生产的水供家庭使用，后处理过程中，往往聘用，以确保产品的水质符合卫生标准饮用水以及推荐的审美与反腐蚀的标准。 Desalination product water may be used in its pure form (eg, for make-up water in power plant boilers) or it may be mixed with less pure water and used for drinking water, irrigation, or other uses.海水淡化的产品水可用于在其纯粹的形式（例如，在化妆水在电厂锅炉） ，也可能混有少纯净水和用于饮水，灌溉，或其他用途。 The desalinated product water is usually more pure than drinking water standards, so when product water is intended for municipal use, it may be mixed with water that contains higher levels of total dissolved solids.该产品的淡化水是通常较单纯，比饮用水标准，因此，当产品水是为市政用途，它可能与水混合含有更高水平的总溶解固体。 Pure desalination water is highly acidic and is thus corrosive to pipes, so it has to be mixed with other sources of water that are piped onsite or else adjusted for pH, hardness, and alkalinity before being piped offsite.海水淡化纯净水是高度酸性，因此，这是腐蚀管道，因此它已经被混在其他水源，这是管道输送的现场，否则调整pH值，硬度，碱度，然后以管道输送外。 Product Water Recovery产品水回收 The product water recovery relative to input water flow is 15 to 50% for most seawater desalination plants.该产品水回收相对投入水流量为15至50 ，大部分海水淡化厂。 For every 100 gallons of seawater, 15 to 50 gallons of pure water would be produced along with brine water containing dissolved solids.每100加仑的海水中， 15至50加仑的纯净水会产生随着盐水含有溶解固体。 A desalination plants recovery varies, in part because the particulars of plant operations depend on site-specific conditions.海水淡化厂的复苏有所不同，其中部分原因是因为当事人的工厂作业依赖于特定地点的条件。 In several locations in California, pilot projects are being proposed to test plant operations before full-scale projects are built.在若干地点，在加利福尼亚州，试点项目正在拟议中的测试工厂作业，然后才全面大规模项目的建成。 Pretreatment Processes预处理过程 Pretreatment processes are needed to remove substances that would interfere with the desalting process.预处理过程中，需要拆除的物质会干扰与脱盐过程。 Algae and bacteria can grow in both RO and distillation plants, so a biocide (usually less than 1 mg/L chlorine) is required to clean the system.藻类和细菌能够在成长中都反渗透法和蒸馏厂，所以杀生剂（通常小于1毫克/升氯气） ，是需要清理的制度。 Some RO membranes cannot tolerate chlorine, so dechlorination techniques are required.一些反渗透膜所不能容许的氯，使脱氯技术要求。 Ozone or ultraviolet light may also be used to remove marine organisms.臭氧或紫外线光也可能被用来去除海洋生物。 If ozone is used, it must be removed with chemicals before reaching the membranes.如果臭氧是用，它必须拆除与化学品才到达膜。 An RO technology has been developed recently that does not require chemical pretreatment.一个反渗透技术已经研制成功，最近不需要化学预处理。 In RO plants, suspended solids and other particles in the feedwater must be removed to reduce fouling of the membranes.在滚装植物，悬浮固体及其它粒子在给水必须拆除，以减少污染的膜。 Suspended solids are removed with coagulation and filtration.悬浮固体去除混凝和过滤。 Metals in the feedwater are rejected along with the salts by the membranes and are discharged in the brine.金属在给水不允随盐由膜，并已出院，在卤水。 With normal concentrations for metals in seawater, the metals present in the brine discharge, though concentrated by the RO process, would not exceed discharge limits.与正常浓度的重金属在海水中，金属，目前在卤水排放，但集中由反渗透过程中，将不会超出排放限制。 Some distillation plants may also need to remove metals due to potential corrosion problems.有些蒸馏厂可能还需要清除金属由于潜在的腐蚀问题。 Filter Backwashing, Membrane Cleaning and Storage, Scaling Prevention and Removal, and Pipeline Cleaning过滤器反冲洗，膜的清洗和存放，防结垢和移除，以及管道清洗 The filters for pretreatment of feedwater at RO plants must be cleaned every few days (backwashed) to clear accumulated sand and solids.该过滤器的预处理给水在滚装植物必须清洗，每隔数天（ backwashed ） ，以明确积累了沙子和固体。 The RO membranes must be cleaned approximately four times a year and must be replaced every three to five years.该反渗透膜必须清理了大约4倍，一年必须更换，每3至5年。 Alkaline cleaners are used to remove organic fouling, and acid cleaners are used to remove scale and other inorganic precipitates.碱性清洁剂是用来去除有机污垢和酸性清洁工人用来去除规模及其它无机沉淀物。 All or a portion of RO plants must be shut down when the membranes are replaced.全部或部分滚装厂必须关闭时，膜的更换。 When RO plants are not used continuously, the RO membranes must be stored in a chemical disinfection/preservation solution that must be disposed of after use.当滚装植物是不会持续使用，反渗透膜，必须存放在化学消毒/保存液必须加以处置后使用。 Distillation plants can also be shut down for tube bundle replacement, which is analogous to membrane replacement.蒸馏厂也可以关闭，进行管束更换，这是类似于膜替换。 Desalination plant components must be cleaned to reduce scaling-a condition where salts deposit on plant surfaces, such as pipes, tubing or membranes.海水淡化厂的部件必须清洗，以减少结垢的条件，如盐矿床于植物表面，如水管，油管或膜。 Scaling is caused by the high salt concentration of seawater and can result in reduced plant efficiency and corrosion of the pipes.结垢是由高盐浓度海水，可以导致降低机器的效率和腐蚀的水管。 In general, scaling increases as temperature increases; thus scaling is of greater concern for distillation plants, since RO plants require lower temperatures to operate.一般来说，结垢的增加，因为温度增加，因此结垢是更令人关注的蒸馏厂，自滚装植物需要更低的温度下运作。 Scaling can be reduced by introducing additives to inhibit crystal growth, reducing temperature and/or salt concentrations, removing scale-forming constituents, or seeding to form particles.结垢可减少引入添加剂，以抑制晶体生长，降低温度和/或盐的浓度，除垢形成的选民，或播种，形成粒子。 Once scales have formed, they can be removed with chemical or mechanical means.一旦规模形成，他们可以去除化学或机械手段。 In addition to scaling, both RO and distillation plant intake and outfall structures and pipelines can become fouled with naturally occurring organisms or corroded.除了缩放，既反渗透法和蒸馏厂进水口和排污渠结构和管道能成为犯规，与自然发生的有机体或锈蚀。 Structures and pipelines may be cleaned by mechanical means or by applying chemicals or heat.结构和管道，可清洗机械手段或采用化学品或热量。 Feedwater may also be deaerated to reduce corrosion.给水也可能除氧，以减少腐蚀。 Waste Discharges废污水排放 Desalination plants produce liquid wastes that may contain all or some of the following constituents: high salt concentrations, chemicals used during defouling of plant equipment and pretreatment, and toxic metals (which are most likely to be present if the discharge water was in contact with metallic materials used in construction of the plant facilities).海水淡化厂所生产的液体废料可能包含全部或部分以下三方：高盐的浓度，化学品使用期间defouling的工厂设备和预处理和有毒金属（其中最有可能被目前如果排放水接触金属所用的材料建造的核电厂设施）的保护。 Liquid wastes may be discharged directly into the ocean, combined with other discharges (eg, power plant cooling water or sewage treatment plant effluent) before ocean discharge, discharged into a sewer for treatment in a sewage treatment plant, or dried out and disposed of in a landfill.液体废物，可直接排放到海洋，再加上其他排放物（如电厂冷却水或污水处理厂的污水） ，然后海洋排放，排放到污水处理的污水处理厂，或干涸，并弃置在堆填区。 Desalination plants also produce a small amount of solid waste (eg, spent pretreatment filters and solid particles that are filtered out in the pretreatment process).海水淡化厂也生产少量的固体废弃物（如用预处理过滤器和固体微粒过滤列于预处理程序） 。 For example, the capacity of the City of Santa Barbaras desalination plant is 7,500 AF/yr (about 7.16 MGD).举例来说，容量的城市圣巴巴拉的海水淡化厂，是7500个自动对焦/里亚尔（约7.16 mgd ） 。 In May 1992, the plant produced 6.7 MGD of product water and generated 8.2 MGD of waste brine with a salinity approximately 1.8 times that of seawater. 1992年5月，该厂生产的6.7 mgd产品的水和产生8.2 mgd废卤水盐度约1.8倍的海水。 An additional 1.7 MGD of brine was generated from filter backwash.另外1.7 mgd卤水产生后，从滤池反冲洗。 Assuming that concentrations of suspended solids in the seawater feed range from 10 to 50 ppm, approximately 1.7 to 5.1 cubic yards per day of solids were generated, which is equivalent to one to two truck-loads per week.假设浓度的悬浮固体量，在海水饲料范围从10到50 ppm ，使用约170 to 5.1立方码每天的固体产生，即相等于1时59分货车荷载每星期。 (Source: Woodward-Clyde Consultants, EIR for the City of Santa Barbara and Ionics, Inc.s Temporary Emergency Desalination Project, March 1991.) （资料来源：伍德沃德-克莱德顾问，审查机构，为城市圣塔芭芭拉和对Ionics公司奇摩临时性紧急海水淡化项目， 1991年3月） 。 Energy Use能源使用 The energy used in the desalination process is primarily electricity and heat.能源用在海水淡化过程中，主要是电力和热力。 Energy requirements for desalination plants depend on the salinity and temperature of the feedwater, the quality of the water produced, and the desalting technology used.所需能源为海水淡化厂在很大程度上依赖于盐度和温度的给水，水的质量产生了，和除盐技术的使用。 Estimates for electricity use requirements for various technologies for seawater desalination are:估计用电量的要求，各种技术，海水淡化是： In addition to electricity requirements, MSF, MED, and some VC plants also use thermal energy to heat feedwater.除了电力需要，无国界医生，医学，和一些VC的植物，也利用热能加热给水。 (Because of the inefficiency of converting thermal energy to electricity, there is a high energy penalty if electricity is used to heat feedwater.) For example, in addition to the 3,500 to 7,000 kWh/AF of energy required for electricity, the thermal energy needs for a MSF distillation plant is estimated at 270 million Btu/AF (about 26,000 kWh/AF); for MED plants, the estimated additional thermal energy requirements are 230 million Btu/AF (about 22,000 kWh/AF). 1 Consequently, the total energy needs for distillation technologies are higher than for RO technologies. （由于政府工作效率低下的转换热能电力，因此是一个高能量的罚款 ，如果电力是用来供热给水） 。举例来说，除了以3500年至7000年千瓦时/自动对焦的能源所需的电力，热力能源需求为无国界医生蒸馏厂，估计在2.7亿美元价/自动对焦（约有26000千瓦时/自动对焦） ，而地中海植物中，估计有额外的热能所需经费2.3亿元价/自动对焦（约22000千瓦时/自动对焦） 。 1 因此，其总的能源需求，为蒸馏技术是高于反渗透技术。 Energy use requirements for desalination plants are high.能源的使用要求，为海水淡化厂高。 For example, an estimated 50 million kWh/yr would be required for full-time operation of the City of Santa Barbaras desalination plant to produce 7,500 AF/yr of water.举例来说，据估计， 千瓦时/年，将需要全时间的运作，该市的圣巴巴拉的海水化淡厂，生产7500个自动对焦/年的水。 In contrast, the energy needed to pump 7,500 AF/yr of water from the Colorado River Aqueduct or the State Water Project to the Metropolitan Water District (MWD) of Southern California is 15 to 26 million kWh/yr.相比之下，能源需要泵7500个自动对焦/年的水来自科罗拉多河，兴建输水管道或国家的水利水电工程，以大都市水区（分布）的南加州是15至千瓦时/年。 These energy requirements may be compared to the energy use of a small- to medium-sized industrial facility (such as a large refinery, small steel mill, or large computer center) which uses 75,000 to 100,000 kWh/yr.这些能源条件的，方可相比，能源使用的一个小型到中型的工业设施（如大型炼油厂，小轧钢厂，还是大型计算机中心） ，其中利用75000至10万千瓦时/年。 Both RO and distillation plants can benefit from cogeneration plants to reduce energy use.双方反渗透法和蒸馏厂可受惠热电厂，以减少能源的使用。 Since increased energy use may cause adverse environmental impacts, the individual and cumulative impacts of energy use and production at a proposed desalination plant will require case-by-case analysis.由于提高了能源使用可能造成对环境的不良影响，对个人和累积影响，能源的使用和生产，在拟议的海水淡化厂将要求逐案分析。 Comparison of Distillation and Reverse Osmosis Technologies比较蒸馏和反渗透技术 One advantage of distillation plants is that there is a greater potential for economies of scale.的一个好处是蒸馏厂是有一个更大的潜力，形成规模经济。 Distillation plants also do not shut down a portion of their operations for cleaning or replacement of equipment as often as RO plants, although distillation plants can and have shut down for tube bundle replacement and cleaning.蒸馏厂也没有关闭自己的部分业务，为清洗或更换设备经常滚装植物，虽然蒸馏厂可以且已经关闭，进行管束更换及清洁工作。 Pretreatment requirements are greater for RO plants, because coagulants are needed to settle out particles before water passes through the membranes.预处理要求更大滚装植物，因为混凝剂，是需要解决的微粒，然后水穿过膜。 Unlike RO plants, distillation plants do not generate waste from backwash of pretreatment filters.不像滚装厂，蒸馏厂不产生废弃物，从冲洗的预处理过滤器。 Advantages of RO plants over distillation include: RO plant feedwater generally does not require heating, so the thermal impacts of discharges are lower; RO plants have fewer problems with corrosion; RO plants usually have lower energy requirements; RO plants tend to have higher recovery rates-about 45% for seawater; the RO process can remove unwanted contaminants, such as trihalomethane-precursors, pesticides, and bacteria; and RO plants take up less surface area than distillation plants for the same amount of water production.优势滚装植物超过蒸馏包括：反渗透厂给水一般并不需要加热，所以热的影响，排放低;滚装植物少出现腐蚀;滚装植物通常有较低的能源需求;滚装植物往往有较高的回收率- 45 左右，为海水;滚装过程中，才能消除有害污染物，如三卤甲烷母质，杀虫剂和细菌;滚装和植物采取了以下表面积比蒸馏厂，为同等数量的水生产。 Costs of Desalinated Water成本的淡化水 The cost to produce water from desalination depends on the technology used and the plant capacity, among other factors.成本生产用水由海水淡化取决于所使用的技术和核电厂的能力，除其他因素外。 For example, the cost of desalted water in Santa Barbara ($1,900/AF) results from the following: a write-off of the capital cost over a short five-year period, high financing costs, and high energy costs.举例来说，成本的脱盐水在圣巴巴拉（元1900/af ）结果如下：注销资本成本较短短5年间，高融资成本，能源成本高企。 The overall