Performance of the 12,000 m3/d seawater reverse osmosis desalination plant at Jeddah,Saudi Arabia January 1979 through January 1981

The operation and maintenance of the world's largest seawater reverse osmosis plant has been largely consistent with expectations. The maintenance down time has been minimized by prompt identification, evaluation and correction of problems.Despite unanticipated mechanical and corrosion problems, the plant has shown a high on-line factor demonstrating the durability and flexibility of spiral-wound elements.In summary, the Jeddah installation has demonstrated that the spiral element can and will function well under varied and adverse circumstances, and that RO is a viable process for seawater desalination with excellent prospects for the future.     

World's first solar powered reverse osmosis desalination plant

Reliable water production to meet the drinking needs of small communities using the technologies of seawater reverse osmosis and solar photovoltaic have been demonstrated. The abundance of sunshine in arid areas makes solar RO particularly viable. Reliable system operation without other power source backup supplies has also been demonstrated. A simple DC power arrangement for the complete system has been shown to be effective.The authors believe this demonstration system is just the start to more and larger solar powered reverse osmosis desalination systems.     

The performance of the 12,000 m3/day seawater ro plant at Jeddah,Saudi Arabia

This paper outlines the performance of the 12,000 m³/day seawater RO plant at Jeddah, Saudi Arabia. The plant started operation in February 1979 and has been operating since then. The feedwater to the plant has a TDS of 42,000 ppm and the maximum seawater temperature is 32°C. The plant is made up of a first and a second stage. The first stage includes nine units, eight operating and one stand-by, and the second stage containes three units. The nine first stage and the three second stage RO units are each composed of 56 Fiberglass pressure tubes (Model 66 FRP-6) 150 mm diameter by 6.5 m long, each containing six spiral wound elements manufactured by UOP Fluid Systems Division. The plant uses Fluid System's polyamide thin film composite membrane element, Model 1501 TFC. The pretreatment is composed of dual media filtration, acid injection, sodium hexametaphosphate injection and cartridge filtration.The performance from the start of operation till the present time is shown both for the overall plant and for each unit. The product rate of each unit and its water quality throughout its operating period is indicated showing the times when the unit was shut-down and the reason for it. Deterioration in unit performance is analyzed and explained. Actual plant consumption of fuel and chemicals is given and estimates of the plant operating costs are made.     

Bench-scale evaluation of seawater desalination by reverse osmosis

In bench-scale tests of seawater reverse osmosis desalination it is important to carefully consider osmotic pressure effects and determine the extent of concentration polarization so that sources of flux variation—whether from fouling, compaction, or osmotic pressure changes—can be properly assessed. Rigorous modeling of concentration polarization is difficult because of the complex geometries and flow regimes in RO modules; typically, concentration polarization must be measured. However, concentration polarization measurement usually requires knowledge of membrane permeability, which can vary from coupon to coupon. In this study a method is presented to determine both the membrane permeability and the concentration polarization regime in a single test. The key to the test is to allow the salt concentration to vary over time in a predictable way and extract parameters from a model fitted to the flux data. The usefulness of this technique is highlighted by evaluating results from several seawater experiments. It was found that specific flux decline in the experiments was caused by changes in osmotic pressure and membrane compaction. RO fouling by seawater organic-matter was not significant for the several seawater samples tested.     

Energy advantages of reverse osmosis in seawater desalination

The very rapid increase in energy costs during the past three years is causing a change in the preferred process technology for seawater desalination. The phase changes, evaporation, and condensation, required in the distillation processes make them more energy intensive than the ambient temperature liquid separation that occurs in the reverse osmosis (RO) process. This paper describes the RO process and how to calculate its energy consultation.The RO process requires only 5–7 KWh/m³ of product water compared to 15–16 KWh/m³ required by the most efficient distillation process. The productivity of a large dual purpose electricity/RO water plant is compared to the productivity of a commercially purchased state-of-the-art dual purpose electric/distillation water plant that is currently under construction. The RO potable water productivity is about 2X the distillate flow at the same fuel rate     

反渗透技术在海水淡化工程中的应用

淡水资源短缺已经成为世界性的难题,各个国家和地区加强海水淡化的研究,采用技术不断提高海水有效利用率,从而缓解水资源短缺现状。反渗透海水淡化技术是一种高效、节能、先进的液体分离技术,已作为重要的主流技术应用在脱盐领域,其突出的特点是成本低。本文论述了反渗透技术和反渗透海水淡化工艺,着重介绍了目前反渗透海水淡化技术的国内外工程应用现状,并提出了对我国反渗透海水淡化技术未来发展的看法。     

Marine reverse osmosis desalination plant — a case study

In the present work, one type of reverse osmosis desalination plant with 2.5 t/d product was introduced. An experimental study was carried out, the result of experiment was analyzed. The calculation data using ROSA software developed by Dow Chemical company was given. By regression analysis of the experimental data, the model correlations were given. The conclusion is that with the increment of operation pressure, the power consumption increased linearly, the flow rate of product and percent recovery increased accordingly, the concentration of product decreased reversibly.     

Elimination of biological fouling in seawater reverse osmosis desalination plants

The main trouble in the RO method of seawater desalination is biological fouling (bio-fouling) from microorganism growth. In this work, the growth rate of microorganisms in the Red Sea and sterilization by chlorine injection were measured and quantified. Furthermore, actual demonstration of RO pilot tests using cellulose tri-acetate (CTA) RO membranes with chlorine resistance was performed in RO plants where bio-fouling actually occurred. By carrying out direct chlorine sterilization of the RO membrane with an intermittent chlorine injection method, bio-fouling was eliminated. The combination of the CTA membrane and chlorine injection successfully prevented increases of differential pressure and stabilized product water quantity and quality.     

Cost analysis of seawater desalination with reverse osmosis in Turkey

Economically usable water resources per capita are decreasing due to excessive population increase each year in Turkey. For this reason, new water resources should be found in the near future. The potential water resources are seawater or well water both of which need removal of salinity. The most promising treatment method for salinity is reverse osmosis. While reverse osmosis becomes widespread, the cost of the process will decrease. There is no detailed information about cost of seawater desalination in Turkey. In this study, a cost analysis of seawater desalination in Turkey was performed for reverse osmosis systems. The basic parameters of cost analysis such as capacity, recovery, membrane life, energy, chemical costs and flux were evaluated based on the effects on capital, operating and total production costs.     

Seawater pretreatment by continuous sand filter for seawater RO (reverse osmosis) desalination plant

Sand filtration is conventionally applied to the preteatment of raw seawater in the RO desalination plant to maintain the seawater quality within the low SDI (Silt Density Index) level. However, the conventional fixed bed type has some difficulties of unstability of the filtrate quality in the backwash period and complicated operation sequence. In solving these difficulties, the applicability of the continuous sand filter has been studied with four years operation at Kure, Japan.The operational result shows that the filtrate is kept in the SDI level of four (4) which is applicable to the seawater RO desalination plant.This continuous sand filter has the advantage of stability, operation and energy saving as compared with the conventional batch type so that our developed continuous sand filter will improve plant economics for the seawater RO desalination plant.     

正渗透策略和化学清洗海水淡化反渗透膜

为解决海水淡化过程中反渗透膜的污染问题,研究了基于正渗透策略的反渗透产水、模拟反渗透浓水、模拟海水不同的组合清洗和清洗时间对膜通量和截留率的影响。针对不可逆污染,研究了不同化学清洗药剂、浸泡时间、浓度对膜通量和截留率的影响。结果表明,正渗透策略清洗方式中,淡水/模拟反渗透浓水的组合清洗方式效果最佳,其归一化通量从9.48 L/(m²·h·MPa)提升至13.6 L/(m²·h·MPa),截留率从80.59%提升至92.80%。此外,经质量分数为2%的柠檬酸溶液浸泡2 h后,再使用质量分数为1%的乙二胺四乙酸四钠盐和0.3%的三聚磷酸钠溶液浸泡1.5 h,其归一化通量从9.48 L/(m²·h·MPa)提升至14.3 L/(m²·h·MPa),截留率从80.59%提升至96.27%。从SEM和AFM图可以看出,正渗透清洗策略并未对膜表面选择层造成损坏,且可以清洗膜表面的有机污染物和无机污染物,因此,应用这种方法对污染的反渗透膜进行清洗,可延长化学清洗周期,减少化学清洗剂用量,具有一定的工业应用前景。     

Forward-osmosis strategy and chemical cleaning of seawater desalination reverse osmosis membranes

In order to settle the membrane fouling of reverse osmosis membranes in seawater desalination process, this study reported a novel strategy based on forward-osmosis process and discussed the effects of different factors like different cleaning combination among reverse osmosis product, simulated reverse osmosis concentrate and simulated seawater, as well as cleaning time on the membrane permeate flux and salt rejection. For irreversible fouling, the effects of different chemical cleaning agents, immersion time and concentration were also investigated in this study. The results exhibited that the cleaning combination between diluted water and simulated reverse osmosis concentrate possessed the best cleaning performance in the process of forward-osmosis cleaning. Such approach also enhanced normalized flux from 9.48 L/(m²·h·MPa) to 13.6 L/(m²·h·MPa) and enhanced NaCl rejection from 80.59% to 92.80%. Furthermore, the normalized flux was enhanced from 9.48 L/(m²·h·MPa) to 14.3 L/(m²·h·MPa) and NaCl rejection was also enhanced from 80.59% to 96.27% after soaking in 2%(mass) citric acid solution for 2h, soaking with 1%(mass) ethylenediamine tetra-acetic acid tetrasodium salt and 0.3%(mass) sodium tripolyphosphate solution for 1.5 h. According to the result of SEM images and AFM images, the forward-osmosis cleaning strategy could not cause the damage of selective layer of membrane surface and caused the drop of inorganic and organic fouling on the membrane surface. Hence, cleaning fouled RO membranes by such approach could prolong the chemical cleaning cycle and reduce the amount of chemical cleaning agent, which has certain industrial application perspectives.     

反渗透海水淡化系统中膜组件的清洗策略

反渗透海水淡化法中膜组件的定期清洗是防治膜污染的主要措施之一.膜清洗可将膜表面的污染物去除,达到恢复透水量的目的.在保证产水量的情况下,选择恰当的清洗策略和清洗时机可使清洗次数最合理,清洗费用最低.以规划期内总操作费用最小为目标,提出了新的污染模型,给出了清洗的判据,将清洗策略问题表达为一个混合整数非线性规划（MINLP）.对一个实例进行计算,给出了该例中的反渗透系统在5年规划期内的最优清洗策略和清洗时机.结果证明这种数学规划方法对于寿命为3～5年的膜组件的清洗维护是有效的.     

Exergy analysis of a seawater reverse osmosis plant

Exergy analysis is a powerful tool to determine how inefficiencies of the processes influence system performance. The exergy analysis of a seawater reverse osmosis desalination plant with 21,000 m³/d of nominal capacity located in Tenerife (Canary Islands, Spain) was studied. Once defined, the flow chart of the process, the exergy rate and exergy cost of flows were determined as well as the exergy destruction rate in equipment. The main results indicate that 80% of the exergy destruction is placed on core processes (high pressure pumping and valve regulation, reverse osmosis separation and energy recovery), 29% extra exergy is necessary to obtain the unit of feed exergy from previous stages (seawater pumping and pretreatment) and extra exergy of 1.06 kJ is needed to generate 1 kJ of final product exergy (exergy performance about 50%). In addition, the moderate fluctuations of seawater environmental conditions in the Santa Cruz de Tenerife metropolitan area (and Canary Islands as a whole) establish that environmental parameters present a less important influence on exergy analysis.     

Demonstration plant for seawater desalination by reverse osmosis (RO-2 hollow fibre module line)

A reverse osmosis (RO) seawater desalination demonstration plant (3000 m³/d with three lines) is being operated in Kuwait to investigate the suitability and optimum operating conditions for polyamide hollow fibre compact modules, and spiral-wound modules.The plant described herein has hollow fibre modules with one high pressure stage of 56–63 bar operating pressure and salt passage of about 1.5%, and a second desalination stage with an operating pressure of 28 bar. Drinking water is made up as mixed permeate from the two stages.During the first year, the RO units operated perfectly, and results obtained exceeded the design values.     

Exergy analysis of a reverse osmosis desalination plant in California

The exergy analysis of a 7250 m³/d reverse osmosis (RO) desalination plant in California was conducted by using actual plant operation data, and an alternative design was investigated to improve its performance. The RO plant is described in detail, and the exergies across the major components of the plant are calculated and illustrated using exergy flow diagrams in an attempt to assess the exergy destruction distribution. The primary locations of exergy destruction were the membrane modules in which the saline water is separated into the brine and the permeate, and the throttling valves where the pressure of liquid is reduced, pressure drops through various process components, and the mixing chamber where the permeate and blend are mixed. The largest exergy destruction occurred in the membrane modules, and this amounted to 74.07% of the total exergy input. The smallest exergy destruction occurred in the mixing chamber. The mixing accounted for 0.67% of the total exergy input and presents a relatively small fraction. The second law of efficiency of the plant was calculated to be 4.3%, which seems to be low. The analysis of the alternative design was based on the exergy analysis. It is shown that the second law of efficiency can be increased to 4.9% by introducing a pressure exchanger with two throttling valves on the brine stream, and this saved 19.8 kW electricity by reducing the pumping power of the incoming saline water.     

Optimization of chemical pretreatment for reverse osmosis (RO) seawater desalination

A total of 40 different experiments to optimize the SDI in the filtered seawater have been conducted and evaluated. Different coagulant-acid concentrations have been dosed in the feed seawater before passing the sand filters. Different concentrations of ferrichloro-sulphate (0.4–1.5 ppm) and sulphuric acid (15–30 ppm) were investigated and the SDI values were measured.Results indicate that SDI values of about 2.0 can be achieved with very low coagulant concentration. This would have great impact on decreasing the consumption of the pretreatment chemicals and on increasing the membrane performance.     

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.     

Seawater reverse osmosis system projects,a manufacturer's viewpoint

A reverse osmosis desalination system will provide excellent service if care is taken in the design, selection, installation and operation of the system. Precautions should be taken not to overly complicate the design and operation. The environment dictates that the highest quality components should be used. Satisfactory operation is highly dependent upon the experience of the manufacturer and the preparations taken prior to installation and commissioning of the system.     

Design and optimization of seawater reverse osmosis desalination plants using special simulation software

This paper introduces the Integrated process simulation environment (IPSEpro™) software, and its application to reverse osmosis desalination.The paper introduces the reader to the basic modeling concepts, and how individual process units can be simply simulated with a graphical, flowsheet style interface.The paper then goes on to describe an example simulation for off design of an integrated pump, membrane rack and isobaric energy recovery device, investigating the effects of changing water quality, membrane condition and also, the influence of isobaric energy recovery device overflush.