The Libyan experimental on the environmental impact assessment for desalination plants

The desalination industries are considered to have a major role in developing human life. Recently this technology became widely distributed, and its construction along the coastal area has been widely reported. Many countries are adopting these technologies for securing the fresh water supply for consumer consumption all over the world. This situation has raised the need for researches to evaluate the environmental impact assessment (EIA) of these technologies on coastal line environment.

This study has been directed to monitor sea water quality used for feeding desalination plants to determine the concentrates of selected pollutants such as heavy metals by using chemical monitoring system to know their effects on the desalination units and other components. This study was conducted in the year 2003 from January to June. Samples were collected from feed water intake of Benghazi North desalination plant and Tobrouk desalination plant, both plants were chosen because of their importance for supplying fresh water for potable water and industrial uses.

The results of this study showed monthly differences in most tested parameters, these differences lead to the scale and corrosion by precipitation on the components of the desalination unites. The objectives of this study is to know the main reasons which caused increasing these concentrates in the sea water (study area) and know how to deal with.     

Analysis of large desalination plants

The experience achieved in the construction and operation since 1973 of the largest MSF desalination unit in the world (8 migd) is the basis for a detailed analysis aiming at contributing to the determination of the practical top size of such units, when taking into account the reliability and engineering problems together with the economical aspects deriving from the MSF unit size.The problem assumes a particular interest when related to the actual trend to limit the maximum unit size normally at 5 migd and in a few cases at 6 migd, with the consequence that some water stations are characterized by a large number of parallel units.     

Design aspects of large sea water reverse osmosis desalination plants

As the size of SWRO plants grow, more attention must be paid to the overall design aspects of the total plant. Some of these are simplifying and improving the pretreatment; reducing the pretreatment chemicals; systems optimization to match sea water conditions and; component size selections.The optimum conversion ratio is generally the maximum possible as limited by brine osmotic pressure and brine flow considerations. This is from 30% to 40% depending on feed temperature and pressure. An economic analysis of cooling of the feedwater is made. This was found to be beneficial for sea water temperatures over 27°C.To utilize larger single streams or “blocks” of permeators, larger high pressure pumps should be employed. These may be driven directly by medium speed diesel engines. A block size of 5 MIGD using a single H.P. pump of 2517 m³/h (11,080 U.S. GPM) at 701m is envisioned.     

Thin film desalination plants and their role in water supply

Our investigation considers the advantages of thin film desalination plants (vertical, horizontal, combined) and their role in water supply.Evaporating horizontal thin film plants proved to be the most effective in economy and power engineering. This paper describes in detail the working processes in different types of pilot desalination plants within the wide range of parameters.As a result, a wide variety of applications of these processes is given.     

Handling of fuzzy decisions in the engineering management of large desalination plants

Engineering managers of large desalination projects often face several alternate strategies, the choice among which is rather unclear due to the lack of specific statistics to favor one choice over the others. Usually, the manager eliminates some options in a preliminary screening process, thus ending with a limited but viable alternative, each of which has its own merits. Fuzzy set theory provides a practicable tool in cases of management decisions under uncertainty where the factors affecting the decision are imprecise in nature. Fuzzy decision-making utilizes the set theory to provide ranges representing subjective judgements in absence of precise quantitative measures. The approach has been formalized in an interactive computer code which can be easily used by managers without the need for familiarization with the theoretical foundations of set theory.The fuzzy decision method is applied here to the problem of selecting management personnel for a large desalination plant in Saudi Arabia. Five alternate strategies are considered; namely use of foreign experts only, extensive use of tested software with minimum reliance on indigent personnel, mixture between the use of foreign personnel and computer software, dependence upon indigent personnel with foreign experience, or the employment of foreign expertise that is gradually phased out and replaced by trained locals. The decision would depend upon a set of attributes that describe the factors affecting the choice of the optimal option. Nevertheless, each attribute has a different degree of effectiveness and a distinct judgemental value for each of the five alternatives. A set of fourteen independent attributes is found for the problem under consideration including costs, lead time, continuity, language proficiency, dedication and compatibility with local culture. Each of the attributes has been provided with a verbal weight indicating level of importance. Then the attributes were ranked for each alternate strategy. Such verbal weights and ratings are input to the computer code called MAFDA to provide a combinetorial. The final analysis showed preferability of introduction of software management techniques followed by training of locals.     

Experimental studies on dynamic process of energy recovery device for RO desalination plants

A two-chamber hydraulic energy recovery unit with a programmable controller and a data acquisition system was set up. Tap water was used as the working fluid instead of the actual seawater and concentrate in SWRO desalination plants. Experimental results were obtained on the fluctuations of the pressure and flow rate to and from the energy recovery unit. Characteristics of the pressure at the chamber ends were discussed at the conditions of the chambers set horizontally or vertically, with and without pistons.     

Application of the multi-effect process at high temperature for large seawater desalination plants

A large sea water desalination plant, using the multi-effect process at high temperature has been described and a comparison is given with the other distillation processes.The multi-effect plant is easily adaptable in a wide range of operating conditions. It has a low total energy consumption (8.75 KWh per m3 produced (expressed as electrical energy). A high GOR is obtained (12.4). Compared with a MSF of the same production capacity, the investment costs are smaller. This leads to a substantial decrease in cost of the produced water. The technology of horizontal sprayed tubes is a proven one and has been executed more than a hundred times on small and medium units.     

Field experiences on large MSF desalination plants designed to operate with two different top brine temperatures

Some design typical aspects of MSF plants, foreseen to be able to operate at different brine temperatures in their hottest zone, are analized; the technical limits of a double condition of operation are examined so as the actions needed to change the operating mode of the plant.Applied design criteria are then compared with operation results of large plants we supplied, evidencing the various problems encountered and illustrating their solution.Finally, a simple method to verify the fouling factor and to prevent scale formation, used in the course of high temperature operation mode, is illustrated.     

Engineering management of nuclear desalination plants—a case study,Saudi Arabia

Engineering management and manpower aspects of potential nuclear desalination projects in non-nuclear countries are considered here with emphasis on safety and quality assurance. Detailed investigation is made of manpower and staffing requirements of dual-purpose nuclear power and desalination plants. Organization and management of typical overall nuclear programs and individual plants are studied to provide specific recommendations of procedures compatible with countries having little or modest industrial activity. Saudi Arabia was selected as a specific case for this study; however, the results apply generally to countries at the same industrial development level. The case of Saudi Arabia is of interest due to the peculiarities of a shortage in human capital and a lack of industries necessary to support desalination and nuclear energy activities.     

Operational data analysis of MSF desalination plants. A case study of Jeddah I

Monthly operation and maintenance reports of the oldest large MSF plant in Saudi Arabia, Jeddah I, are analyzed to extract information or generic operation and design problems and to seek means for the mitigation of such problems. The accumulated records are quantified to provide estimates of equipment failure rates. Three systems are found to be the major contributors to plant outage namely, make-up water, brine recycle and sea water intake systems. Root causes of the plant unscheduled shutdowns or reductions in water production are assessed to examine generic reasons for deviations of MSF systems from standard expected performance.     

渣油大型合成氨装置的现状及其发展趋势

叙述国内外渣油大型合成氨装置的现状和１０大特点，展望近期的发展趋势。     

Treatment of distillates and permeates from seawater desalination plants

Seawater desalination by evaporation or reverse osmosis processes is of rather great importance for potable water supply in countries without sufficient natural water sources. The distillate produced by evaporation as well as the permeate produced by reverse osmosis have to be treated to achieve satisfactory properties with respect to corrosiveness and health aspects.The paper discusses the composition and properties of distillate and permeates and the different remineralization and potabilization processes to make potable water and to avoid corrosion in the potable water system.     

海水淡化发展利用状况分析与启示

我国人均淡水资源相对匮乏,不足全球平均水平的1/4.海水淡化作为沿海地区非常规的新型水资源,为水供应结构的优化和水资源的补充供给提供了有效方式.综述了我国海水资源综合利用的主要形式——海水淡化,及其技术应用.列举了几种常用淡化方法,反渗透法因设备投资少、运行费用及单位制水成本低等优点,运用最为广泛.分析了组合型技术和正渗透、太阳能等一些新型海水淡化技术的特点.对国内外海水淡化的发展利用情况进行了调研,从项目规模、技术、用途、政策等方面进行了分析汇总.探讨了目前海水淡化利用在技术创新、淡化成本、淡化水消纳及环境影响、相关政策标准等方面的问题,并提出了具有一定创新性的应对措施.     

Acid cleaning and passivation of power plant condensers and desalination plants

Experiences of acid cleaning and passivation treatments of copper alloy tubes are described. The suitability of corrosion monitoring to follow each step of such operation is demonstrated.     

城镇污水处理厂碳中和技术及案例

污水是资源与能源的载体,蕴含着极大的化学能和热能,传统污水处理过程以能消能,处理过程能耗高且释放温室气体。在碳中和背景下,我国城镇污水处理厂实现碳中和运行,在能源自给、降低温室气体排放等方面具有潜力,成为城镇污水处理厂转型的热点。本文以城镇污水处理厂碳中和运行潜力分析为背景,分析了以高负荷活性污泥工艺（HRAS）、化学强化一级处理工艺（CEPT）、自养脱氮和反硝化除磷等工艺技术为主的碳源捕捉、低耗处理的新型污水处理工艺,并阐述了以厌氧消化-热电联产、热能和太阳能回收为代表的能源回收技术,以国内外碳中和技术运行的实际污水厂案例探讨了其应用优势和效果。同时,认为低耗运行和能源回收是城镇污水处理厂实现碳中和运行的关键,并对我国城镇污水处理厂实现碳中和运行提出了展望,旨在为城镇污水处理厂的低耗绿色可持续发展提供参考。     

Environmental problems of sitting and operating desalination plants in the United States

Environmental problems of desalination may result from excessive withdrawals of surface water and from indiscriminate discharge of brines differing in chemical character and temperature from ambient conditions. Nature and magnitude of the problem varies with the site of the facility, source of feed water, type of desalination process and discharge practices. This paper documents methods of handling these problems at existing and proposed plants in the United States.     

Environmental problems of siting and operating desalination plants in the united states

Environmental problems of desalination may result from excessive withdrawals of surface water and from indiscriminate discharge of brines differing in chemical character and temperature from ambient conditions. Nature and magnitude of the problem varies with the site of the facility, source of feed water, type of desalination process and discharge practices. This paper documents methods of handling these problems at existing and proposed plants in the United States.     

大型反渗透海水淡化工程能耗降低方法探讨

探讨了降低海水淡化能耗的方法,对能量回收装置性能进行了对比分析,并对大型反渗透海水淡化工程提出了"深井取水 预处理(UF/MF) 高产水量RO膜 AT TURBO/PX"工艺,提高反渗透装置进膜压力、平均膜通量、回收率,降低吨水能耗,对今后大型反渗透海水淡化工程设计有一定的借鉴意义.     

聚酰胺复合正渗透膜的制备及其脱盐性能研究

通过溶液相转化法制备四种基膜,然后采用界面聚合法制备不同基膜的聚酰胺复合正渗透(FO)膜,并对其结构与性能进行表征。结果表明,正渗透膜基膜表面开孔率高、孔径分布均匀,且纯水通量大;在基膜中引入聚酯(PET)筛网使其厚度增大、孔隙率和纯水通量降低。基膜材料为聚砜(PSF)时,复合膜聚酰胺分离层较为疏松,以聚偏氟乙烯(PVDF)为基膜材料,形成的分离层较为致密且具有典型峰谷结构,从而使反向盐通量更小。四种复合膜的正渗透纯水通量均大于10 L/m2·h,最高达20 L/m2·h。120 min连续正渗透脱盐实验表明,复合膜截盐率及其稳定性优于商用膜,尤其PET筛网支撑PVDF基复合膜的截盐率基本稳定在97. 5%左右,表现出良好的运行可靠性。