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The knowledge of the characteristics of seawater is important for designers and engineers to design and construct a desalination plant with low operational problems. Therefore, establishing a database for Kuwait’s seawater characteristics is considered a crucial tool for researchers seeking to develop and improve desalination technologies for future applications. Because of this fact, this project was proposed to analyze the physical, chemical, and biological characteristics of Kuwait’s seawater at Subiya, Doha, Shuwaikh, Shuaiba, and Az-Zour, and other two locations that belong to the Kuwait Institute for Scientific Research (KISR) as Doha Research Plants (DRP) used as the intake for desalination/distillation research activities. A database on Kuwait’s seawater characteristics at the proposed locations was established. Then, the suitability of the proposed locations for future desalination activities was investigated depending on four fouling indices. The results obtained from the investigation of fouling indices were compared to the result obtained from experimental testing. This paper will summarize the results of the analysis and the experimental work and explore the best location for desalination activity in Kuwait and KISR. [ABSTRACT FROM AUTHOR]

Normal growth of phytoplankton means gradual growth that allows mixed community to grow and allow a gradual succession of other phytoplankton species with a balanced and high biodiversity. In the contrary, a rapid, large-scale growth of certain species of phytoplankton is defined as harmful algal bloom (HAB). HABs cause water quality issues in fresh, brackish, and marine waters worldwide. In the Red Sea, HABs hinder normal operation of desalination plants and can even lead to their temporary shutdown. This research has already detailed how wastewater discharge from Red Sea desalination plants helps trigger HABs. The primary objective for this paper is to help manage and even mitigate this problem through development of a model to be used along with satellite images and physicochemical monitoring analysis as an early warning system for HABs near desalination plants in the Red Sea. To develop the model, physicochemical data were collected by sampling three coastal areas near desalination plants at Jeddah, Al Shoaibah, and Al Qunfudhah from December 2014 to November 2016. A total of 1,944 water samples were collected. To understand the unique environment of the seawater around the desalination plant that may trigger HABs, 15 parameters were measured. These parameters were divided into two groups, growth indicators (phytoplankton count, chlorophyll, phycoerythrin, dissolved oxygen, and turbidity) and those that might trigger the growth (temperature, conductivity, salinity, pH, total dissolved solid [TDS], nitrate, nitrite, ammonium, phosphorous, and silica). It was found that the highest concentrations of chlorophyll at Al Qunfudhah often exceeded the critical threshold level of 2 to 5 μg/L, which indicates the presence of an algal bloom. However, at Jeddah and Al Shoaibah chlorophyll concentration did not exceed this level. The results showed that higher temperature, salinity, TDS, and pH may promote some HAB species in environments that promote less phytoplankton diversity. Nitrate, phosphorus, and silica were the major nutrients that can trigger HABs. Prediction equations were developed using data from those parameters that promote HAB occurrence. [ABSTRACT FROM AUTHOR]

Multi-effect desalination with thermal vapor compression (MED-TVC) is particularly more attractive than other thermal desalination systems due to its low energy consumption. One of the major component of MED-TVC desalination system is thermo-compressor. The overall efficiency of the system is directly influenced by the performance of thermo-compressor. It enhances system’s efficiency by reducing the energy consumption. The location of the steam extraction has a great effect on the performance of the MED-TVC plants. Higher gained output ratio of the desalination plant can be obtained at the optimum position of vapor extraction in the MED-TVC system. The optimization of location of suction position of thermo-compressor in MED-TVC desalination plants could result in maximization of gain output ratio (GOR) and consequently reduction in energy consumption. Furthermore, increasing the suction pressure also results in decreasing the energy consumption of the system. Therefore, this work will analyze the impact of suction position of thermo-compressor on the amount of energy consumption, specific heat transfer area, and GOR values of the plant. The effect of thermo-compressor’s suction pressure on the energy consumption of a plant in different configurations of MED-TVC and MED was also analyzed in this work. A detailed mathematical model will be developed for the process in order to find the optimum location of thermo-compressor suction. The effect of changing the suction position of thermo-compressor on the entrainment ratio and the amount of energy consumption of the plant was analyzed. [ABSTRACT FROM PUBLISHER]

In this study, to design an efficient control system for a Reverse osmosis (RO) desalination plant, a model predictive control (MPC) was established and compared to the obtained control system based on proportional–integral–derivative (PID) controllers. In order to control two controlled variables, namely permeate flow rate and conductivity, two PID controllers’ parameters were tuned based on the internal model control (IMC) rule and an MPC controller was established using the dynamic matrix control algorithm. The control performance assessment of both PID and MPC controllers were carried out using prediction error approach and their control performances were compared to that of the PID controllers which tuned by Ziegler–Nichols rule from the literature. The results showed that among the designed controllers, the PID controllers tuned by IMC method are more capable than other controllers to control the considered RO desalination plant. [ABSTRACT FROM PUBLISHER]

The forward osmosis (FO) and reverse osmosis (RO) hybrid process uses seawater and wastewater treatment plant effluent as the FO draw solution and feed water, respectively, and the diluted seawater by FO is used as the RO feed water resulting in the less energy consumption than the conventional seawater reverse osmosis applications. This work developed an optimal design approach of the hybrid process by finding the optimal RO recovery and FO permeate flow rate. The optimized RO recovery (e.g. 38.5–66.7% according to the FO permeate flow rate) determined by solving an optimization problem based on the mass balance in the FO-RO hybrid process, minimizes the RO energy consumption (1.86–3.49 kWh/m3at 25°C and 2.41–3.86 kWh/m3at 5°C). The RO energy consumption decreases as the RO recovery increases until it reaches an optimal value. The optimal FO permeate flow rate can be defined with three different perspectives: (1) to minimize the RO energy consumption, (2) to minimize the RO feed flow rate, and (3) to minimize the environmental impacts of the concentrate discharge. Thus, the optimal FO permeate flow rate should be determined based on the weights of the three perspectives. The energy saving achieved by the optimal design approach in this work ranges from 37.6 to 46.7% according to the temperature. [ABSTRACT FROM PUBLISHER]

The objective of this paper is to present a methodology to predict vacuum load theoretically and to compare those results with the experimental values for validation especially the non-condensable gas load and escape water vapour load. The primary objective of this paper is to find out the accumulated effect of non-condensable gases on the vacuum load of low-temperature thermal desalination (LTTD) plant. Suggestions to control the NC gas and escape vapour load on the LTTD process were also discussed in this paper. Determination of an exact amount of vacuum load for the plant is significant, since vacuum system alone shares about 31% of total energy demand of the LTTD plant. Load contribution given by the gas mixtures such as escape water vapour, non-condensable gas and air leak in to the system was experimentally measured by conducting suitable experiments in a running plant of 100 m3/d capacity located in the Island of Agatti, UT Lakshadweep group of Islands, India. Study at Kavaratti plant of same capacity showed that the escape vapour rate was equivalent to 0.3% of the freshwater generation rate of the plant, which was used as an input value for Agatti vacuum load calculation for escape vapour rate. On comparison of the experimental results of non-condensable gas release rate of Agatti plant with the published data and predicted values using methodology, an agreement up to 16 and 7.7% was obtained, respectively, under the same operating conditions. Also, an agreement up to 15% was obtained between the experimental results of Agatti plant with that of observed results of Kavaratti for water vapour escape rate from the main process condenser. It was reported in the literature that for MED desalination system, the extraction of vapour from the evaporator unit linked with a removal of 10–20 units of vapour corresponded to every unit mass of NC gases. But in the present study, for the LTTD process, it was measured that the accumulated effect of NC gases for every unit mass resulted in extraction of 1.6 unit mass of vapour (approx) from the process condenser. This low value could be due to low operating temperature range of LTTD process and use of low-temperature deep-sea cooling water from the ocean in the condenser tubes. From calculation, it was noticed that decrease in molecular weight of gas increased the volumetric vacuum load for the same operating conditions and gas mass flow rates. Also, it was observed that the parameters such as operating pressure, duct loss, mass flow rate of feed water influence the total vacuum load of LTTD plant. [ABSTRACT FROM PUBLISHER]

Nowadays, the most important problems that affect the world are carbon footprint decrease, fossil fuel use, and climate change. As proof of that, all environmental international agencies impose different laws and rules related to greenhouse effect. European Union policy is a clear example, which is explained in the document “2020 Strategies (COM/2010/2020 final)” [1]. Water deficit is another question that produces a lot of problems around the World. About 1,100 million people lack access to safe drinking water, which represents 18% of the world population. Approximately 42% of the population is not able to access basic sanitation. The project raised different problems related to water and energy production. The primary goal is to achieve low carbon emissions. Moreover, these dual plants (desalination and thermal power plants) should be more efficient and flexible. The project’s main goal is to study water and energy cogeneration in half power thermal power plants through different docking ways. The system is approached to be installed in areas where water is not sufficient. [ABSTRACT FROM PUBLISHER]

A new membrane-based method was applied to investigate the performance of three phosphorus-free antiscalants of different chemical structures to prevent calcium carbonate scale. Apart from a polyacrylate homopolymer, two copolymers were studied, one of it also being free of nitrogen. The results show that an inhibition of CaCO3scale on reverse osmosis (RO) membranes is possible with phosphorus-free antiscalants. The individual performance strongly depends on the chemical structure of the polycarboxylate. A specially adapted copolymer clearly outperforms the polyacrylate homopolymer in case of severe scaling conditions. The average residence time of the water in the test plant is approximately 1 h, compared to around less than a minute in a full-scale RO plant. So the operating conditions in the test plant make it more difficult for an AS to inhibit scaling compared to a full-scale RO plant. By energy-dispersive X-ray fluorescence (EDXRF), the scaling layer thickness can be estimated. The SEM images and the 3D images from CLSM showed that the water quality and the applied antiscalant have a great influence on the scaling layer morphology. The effective blocking of the membrane does not only depend on the amount of precipitated CaCO3but there is also a great influence of the scaling layer structure. With a normal scaling potential of the water, the scaling layer consists of calcite, and at higher LSI values of the feed water, there was also aragonite found on the membrane. From the three antiscalants AA/AMPS shows, as it was expected, the lowest performance as calcium carbonate scale inhibitor, because it is designed predominantly as a disperser and as stabilizer for calcium phosphate. PAA proved to be an efficient inhibitor for hardness at standard applications. For the application in waters with high scaling potential, AA/EA is very suitable, because this inhibitor is able to serve as a good stabilizer for hardness and at the same time as a disperser. A combination of different polymers enables special solutions for high requirements. [ABSTRACT FROM PUBLISHER]

Solar multi-effect desalination (SOLMED) is a new technology based on low-temperature multi-effect distillation (LT-MED). The project aims at sea water desalination on vertical polymer tubes using thermal solar energy, or low-grade thermal waste energy. This paper presents experimental results of a test rig with a single polyolefin tube of 70 μm thick. Hydrodynamic and thermal tests were carried out in order to characterize the heat transfer. It was found that salt water flow on the outer surface of the tube improves the falling film wetting over time. Results of the overall heat transfer coefficient are presented and compared to other studies. Achieved values ranged from 1,300 to 2,600 W/m2 K. Finally, two new correlations were developed from the experimental data to predict heat transfer coefficients for film evaporation outside the tube and dropwise condensation inside the tube. [ABSTRACT FROM PUBLISHER]

Water resources available in the island of Fuerteventura come mostly from small-scale capacity seawater desalination plants. Desalted water demand in the island has grown considerably in the last decade forcing managers to adapt desalinated water supply constantly. Additionally, the operating cost of the plants is relevant. The staff, chemical consumption, cartridge filter, and membrane replacement cost are essential in order to establish more efficient operation conditions of a reverse osmosis desalination plant. This article aims to study and compare the mentioned cost of six different seawater reverse osmosis desalination plants with the same production of 600 m3/d in the island of Fuerteventura. The results show for each of the six cases how costs can be reduced and the essential role of automation dealing with the staff cost with the particular capacity of 600 m3/d. [ABSTRACT FROM PUBLISHER]

Being a basic element for the every existence of any form of life on earth, water is one of the most abundant resources on earth, covering three-fourth of the planet’s surface. However, there is a shortage of freshwater in many areas worldwide. Desalination seems to be the most suitable solution. Major conventional desalination processes, such as distillation and reverse osmosis, consume a large amount of energy derived from oil and natural gas as heat and electricity, which is responsible for harmful CO2emission. Solar desalination has emerged as a promising renewable energy-powered technology for producing freshwater. Solar membrane distillation (MD) is the best option in decentralized regions with scattered population and lack of infrastructures jointly with hard climate conditions make it difficult or at least not cost-effective to scale down bigger desalination technologies, such as RO or MSF, designed for very big water productions. Moreover, MD compared to conventional thermal desalination is less demanding regarding vapor space and building material’s quality leading to potential lower construction costs. The aim of this paper is to present the state-of-the-art review of developments in solar MD technology. In this review, membrane configurations, module design, and recent applications of this technology were discussed in detail. [ABSTRACT FROM PUBLISHER]

The Canary Islands has been pioneer on desalination in Europe since the 1960s and has continued to use intensively the desalination technologies in order to provide water resources. However, one of the most important problems related to the operating efficient of seawater reverse osmosis (SWRO) desalination plants is dealing with the high-energy consumption. The present article aims to study, define, and compare the energy consumption cost of five SWRO desalination plants with the same production of 4,000 m3/d in the island of Fuerteventura (Canary Islands). The methodology for carrying out the work is based on analyzing the energy consumption data that directly affect to the operating cost. A comparison between different energy recovery systems was carried out using the data collected over 5 years of operation. The article presents an assessment of different ways to get more efficient operating conditions in order to reduce the operating cost. [ABSTRACT FROM PUBLISHER]

A noticeable increase in the number of seawater reverse osmosis (SWRO) desalination plants has been observed during the last decade. This is due to the low energy consumed by reverse osmosis technology and the high freshwater recovery when compared to other desalination technologies. The desalination of seawater is the main source of freshwater in Kuwait. However, SWRO desalination plants generate huge volumes of concentrated brine, which is considered a potential source of mineral content. Some of these minerals are expensive and scarce on earth. The recovery of these minerals from brine can help in increasing the freshwater recovery, reducing the overall cost of desalinated water, offering a new source of raw materials, and decreasing the environmental impact from discharging brine to the sea. This study gives an overview of the different technologies used for the treatment of SWRO brine and explores the benefit to recover and reuse valuable potential minerals in brine. The study is motivated by the strong need to establish a local industry in Kuwait based on the extraction of potential valuable minerals from SWRO brine. Such industries can be combined with desalination plants to form a complex cogeneration of plants that accommodate desalination and power plants. [ABSTRACT FROM PUBLISHER]

The performance of desalination and sewage treatment plants operated by contractors at sites of a large company in Oman was evaluated in relation to benchmark costs. Such benchmark costs, which are dependent on plant size and process used, were established based on estimates provided in research literature and based on site-specific estimates made using software models. Desalination economic evaluation program software was used to estimate site-specific costs of desalination and financing for environmental, affordable, and strategic investments that bring on large scale expenditure software was used to estimate site-specific costs of sewage treatment. The estimated site-specific benchmark cost of desalination was 1.20 US$/m3. The desalination cost subject to many variables reported in the literature ranges between 0.52 and 1.30 US$/m3. The estimated site-specific benchmark operational cost of sewage treatment up to the BOD level of 10–15 mg/L of treated water was 0.29 US$/m3. The cost of sewage water treatment, up to the BOD level of 10–15 mg/L of treated water, averages to 0.41 US$/m3based on studies conducted. The evaluation of costs reveals that the cost of desalination and sewage treatment at the company sites was close to benchmark costs provided in the research literature as well as site-specific estimates made using software models. [ABSTRACT FROM PUBLISHER]

Today, most RO desalination plants are using phosphorus-based antiscalants for preventing salt precipitation (scaling) and to achieve high membrane performance, as measured by reduced trans-membrane pressure, salt passage and increased permeate flow. However, phosphorus antiscalants in brine disposal can be an environmental issue that should be considered and studied when installing a desalination plant. The purpose of this research is to examine different types of phosphorus-free antiscalants and to find combinations of good membrane performance (varied recovery rates) and environmental antiscalants. Together, the Granot and Lahat BWRO desalination plants will produce approximately 30 Mm3in 2014. They are part of a large project: “The Aquifer Rehabilitation,” which aims to protect the Israeli costal aquifer from saline infiltration. The concentrate from these inland BWRO desalination plants is sent along a unique 30-km-long brine disposal pipeline to the Mediterranean Sea (“Granot-Ashkelon” pipeline). Obviously, the preferred phosphorus-free antiscalant should prevent salt precipitation (scaling) in both the RO membranes and the lengthy brine disposal pipeline. The use of phosphorus-free antiscalant should achieve stable membrane performance. To date, five different antiscalants (four of them, phosphorus free) were tested at a pilot plant at the Granot site. This BWRO pilot plant contains two systems: (i) the desalination branch, which has similar alignment and pre-treatment as the Granot desalination plant, and (ii) a brine flow system that simulates true brine flow conditions. This system was used to validate the possibility of salt precipitation in the long brine pipeline. Experiment results carried out on four phosphorus-free antiscalants show that stable membrane performance did not occur. This research continues in pursuit of compounds that can satisfy the increasingly stringent environmental requirements in this field. According to the experiments schedule, additional phosphorus-free antiscalant will be tested in Granot BWRO pilot plant. [ABSTRACT FROM PUBLISHER]

Horizontal-tube falling film technology is widely used in multi-effect desalination plant. The film characteristics of falling water film outside the tubes in horizontal-tube falling film evaporator were simulated. The numerical result was compared with the experimental result and they were proven with good agreement. The film thickness distribution at different Reynolds number and different circular angle had been investigated. Also, the effects of liquid flow rate and tube diameter on the film thickness distribution were discussed in detail. Numerical simulation result shows that, with the increase in Reynolds number, the falling film thickness at a certain circumferential angle increases with almost linear growth rate, and the thinnest film at the surface of the tube appears at the angle of about 120°. The result also indicates that the local dry out spot on the surface of the tube would occur when the fluid flow rate decreases to a certain value. In addition, the film thickness decreases with the increase in the tube diameter at a fixed fluid flow rate. [ABSTRACT FROM PUBLISHER]

Research in cleaning procedures of reverse osmosis membranes used in seawater desalination to minimize costs and achieve high efficiency is necessary. Multi-step cleaning can represent a useful tool, since the cleaning efficiency can be improved by means of utilization of different chemicals with complementary cleaning mechanisms. The objective of this work was the optimization of a two-step cleaning procedure to recover the membrane properties and reduce power costs. Spent Hydranautics SWC3 membranes (USA) were supplied by a desalination plant. Cleaning tests were performed in three stages: one-step static cleaning, two-step static cleaning and characterization of the membrane surface after the cleaning process. Four cleaning agents at two different concentrations were used. All possible combinations of them were considered, including sequence effect. After the cleaning process, membrane surface was characterized by field emission scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and atomic force microscopy. One-step static cleaning test indicated that sodium dodecyl sulphate 1% w/v was the most efficient cleaning solution, followed by NaOH 2% w/v. Two-step cleaning tests showed that the procedure that maximized permeate flux recovery was surfactant-alkaline cleaning, whereas the one that maximized the recovery of the salt rejection index was alkaline-acid sequence. Characterization of the membrane surface after the cleaning steps confirmed that fouling deposits were significantly removed. [ABSTRACT FROM PUBLISHER]

In order to get a better understanding of distribution characteristics of the dynamic and heat transfer performance in a horizontal-tube evaporator, a numerical calculation was developed to simulate the internal film condensation and external falling film evaporation in a tube bundle. The temperature field, film thickness and local heat transfer coefficient were predicted along the tube length and in-between tubes. In view of a good agreement of the simulated predictions with the data of the practical desalination plant, the theoretical model was proved to be valid and accurate. The results show that the flow field and heat transfer rate are improved by means of optimizing the flow density distribution of liquid film outside a tube bundle on basis of the variation of the internal condensation process. The internal vapour condensation temperature reduces sharply at the outlet of the second pass. The local overall heat transfer coefficients tend to decrease from the inlet of the tubes to the outlet and approach the maximum at the bottom of the bundle. [ABSTRACT FROM PUBLISHER]

The scarcity of drinking water resources in Cyprus has started becoming a major issue during the past decades, as a result of prolonged draughts and failure to implement a sustainable water conservation and management policy. Cyprus, a semi-arid classified area in the Eastern Mediterranean, has traditionally been relying on water reservoirs for the collection and treatment of rainwater destined for human consumption. Seawater desalination has been introduced during the past 15 years as a means of alleviating the drinking water shortage problem and complementing the dam reserves; however, the usage of desalinated water has not yet been optimized. As a result, desalination plants have been constructed and shut down after only short operation times, some have been built and commissioned only to be put on standby mode soon after, while construction of others was postponed until it was too late to cope with water shortage problems etc. This situation has been creating a series of problems associated with potable water quality in general and other numerous anomalies being observed in the distribution network, the most important of which are the following:Water shortage during peak periods (e.g. summer months when demand rises sharply due to tourism and irrigation needs).Blockage at terminal points of the distribution network.Bad odour and unpleasant smells observed at consumption points.Elevated heavy metal concentrations in potable water supplies.Elevated THM’s concentrations in potable water supplies.Corrosion of metal piping in the distribution network. This study shall examine these problems in depth and provide suggestions that will help in establishing a truly sustainable drinking water policy on the island. [ABSTRACT FROM PUBLISHER]

Seawater reverse osmosis (SWRO) desalination technology has been rapidly growing in terms of installed capacity and global application over the last decade. An emerging threat to SWRO application is the seasonal proliferation of microscopic algae in seawater known as algal blooms. Such blooms have caused operational problems in SWRO plants due to clogging and poor effluent quality of the pre-treatment system which eventually forced the shutdown of various desalination plants to avoid irreversible fouling of downstream SWRO membranes. This article summarizes the current state of SWRO technology and the emerging threat of algal blooms to its application. It also highlights the importance of studying the algal bloom phenomena in the perspective of seawater desalination, so proper mitigation and preventive strategies can be developed in the near future. [ABSTRACT FROM PUBLISHER]

Most marine algal species are beneficial, not harmful, as algae are the foundation of the food chain and provide the bulk of Earth’s oxygen through photosynthesis. Mankind also commercially harvests algae for a myriad of uses in the food, pharmaceutical and medical industries to name but a few. However, the sudden prolific growth in algal cell numbers, referred to as harmful algal blooms (HAB), can constitute an operational and/or health risk to desalination plants, threatening water supply security and safety, respectively. The excessive biomass and organics associated with HAB can lead to the closure of desalination plants, particularly sea-water reverse osmosis (SWRO) plants due to overloading of the pretreatment facilities or potential irreversible RO membrane fouling. While these impacts are well documented, the removal of potent marine algal toxins, which represent a potential public health risk if not removed by desalination plant processes, is not well researched. The incidence of HAB has escalated throughout the world with algal specialists reporting that “compared to 30 years ago, we have more algal toxins, more toxic algal species and more areas affected”. Therefore, this paper examines the major marine algal toxins that may be present at the intake of a desalination plant, their fate in thermal and SWRO desalination plant processes and the potential residual risk to public health in desalinated drinking water. Toxin removal in the various process steps is predicted based on the physico-chemical properties of these marine toxins. Results from bench and pilot studies investigating the efficacy of barriers in the desalination technology processes to remove cell-bound toxins and extracellular toxins from ruptured algal cells are also reviewed. [ABSTRACT FROM PUBLISHER]

Several high alloys are candidate materials for the severe corrosive environment of reverse osmosis desalination plants. In the present study, the crevice corrosion performance of duplex, superduplex, superaustenitic stainless steels, and nickel-based alloy was investigated in natural and chlorinated seawater, at different temperatures. Several crevice configurations were evaluated including flanges assembled with gaskets, bolts mounted with nuts to plates, and the standard CREVCORR-type crevice formers. It was thus possible to illustrate the effect of crevice configuration on the corrosion behavior of the different alloys. The crevice geometry was confirmed to be of major importance in terms of risk for initiating crevice corrosion. In natural seawater (i.e. not chlorinated), the most severe temperature was 30°C, due to high biological activity and high corrosion kinetics. Chlorination at 0.5 ppm increased the risk of localized corrosion but decreased the corrosion propagation rates. In chlorinated seawater, crevice corrosion risk significantly increased with temperature for all tested alloys. For each of the tested configurations, the superaustenitic stainless steel UNS S31266 showed better crevice corrosion resistance than superaustenitic UNS S31254 and S34565, superduplex S32750, and also nickel-based alloy N06625. The present results are part of a three-year Joint Industry Program supported by end-users, engineering companies, and material producers. [ABSTRACT FROM PUBLISHER]

This paper demonstrates the performance examination of an integrated membrane system (IMS) pilot plant having capacity of 250–300 L/h for oil refinery wastewater reuse of oil refinery plant in Indonesia. The IMS pilot plant consisted of a multimedia filter (MMF), an ultrafiltration (UF) unit, a reverse osmosis (RO) unit, and a membrane bioreactor (MBR) unit. The UF system was used as a pretreatment prior to RO, the RO unit was used to produce cooling water make-up and the MBR system was used for treating RO concentrate. The test results suggested that backwashing with a more frequent interval is needed to maintain stable flux of UF membrane. With the cleaning every 14 days, the resulting RO permeate was stable and able to fulfil the plant requirements of cooling water make-up. Treatment of RO concentrate using MBR unit resulted in permeate having relatively high chemical oxygen demand (COD). Further treatment by adsorption using granular activated carbon (GAC) proved that GAC was an effective method for reducing the COD level. [ABSTRACT FROM PUBLISHER]

Seawater desalination in the capacity range 100-1000m²/day is globally of increasing importance, especially when it comes to in remote costal regions. By meeting the energy demand of desalination plants by using renewable energy technologies, the environmental impact can be minimised. For water production of more than a few cubic meters per day, usually conventional constantly operating desalination systems are used requiring the implementation of expensive energy storage systems and/or a grid-connection. Variable operating SWRO plants could eventually increase the efficiency of an energy supply system by minimising the otherwise unavoidable dump load and the capacity of energy storage systems. To provide evidence for this thesis, data of the Cape Verdean Island Brava were used and three main scenarios compared. Simulations using hourly data-sets show that energy supply systems with a high wind share can benefit from deferrable loads like a variable desalination plant. Based on their flexibility, such processes are very attractive to implement as dynamic load in stochastically fluctuating renewable energy supply systems. Technological requirements for a variable operation of a SWRO plant are described, considering pressure changes and interruptions of the energy supply and water flow. For the simulation, a preliminary plant design configured by SYNLIFT Systems is used. A detailed analysis of levelised costs of water and electricity highlights options, how desalination could be applied as deferrable load in gridconnected systems in a technologically feasible and economically profitable way. [ABSTRACT FROM AUTHOR]

The increasing water demand and the impacts of climate change call for the construction of a large number of new desalination capacities, causing--besides environmental impacts--a relevant amount of additional power consumption. Consequently, new power plants need to be installed and operated as base load plants in order to supply power continuously to the desalination units. As fossil fuel prices are characterized by high volatility and a clear trend upwards, the use of renewable energies allows for saving fossil fuels and therewith reducing risks related to energy price escalation along the whole desalination life cycle. However, the fluctuant nature of renewable energies conflicts with the--ideally--continuous operation of desalination plants. In contrast to technologies such as photovoltaic (PV) and wind power, which are prone to fluctuating and intermittent power generation, concentrating solar power (CSP) is able to supply firm capacity on demand and can be fully integrated into conventional power utilities. On the other hand, CSP is currently considered to be more expensive than other renewable energy technologies. This work highlights the key importance of comparing technology options with equal quality of supply in order to obtain resilient results. Within this work, a representative site in the Middle East and North Africa Region has been analyzed by two different methodologies in order to demonstrate the potential large difference of results. The first method assumes that any variations of renewable energy supply can be compensated by the electricity grid, while the second method assumes that the addition of load to the electricity grid will require the addition of an equivalent firm power supply capacity. Hourly solar and wind data of a typical meteorological year have been used as inputs for a techno-economic simulation. Different options for CSP solar field layout, thermal energy storage, PV, and wind installed capacity, are analyzed and compared in terms of power and water cost for reverse osmosis and multieffect distillation plants. [ABSTRACT FROM AUTHOR]

For several decades, multiple stage flashing (MSF) has been the main stream in thermal seawater desalination process due to its stable and robust performance. In the Middle East region, MSF units of large capacity evaporators have generally been supplied. Meanwhile, the multiple effect desalination process with thermal vapor compression has recently been receiving attention because of the lower energy consumption. Dynamic simulation of thermal desalination plant could be used to validate plant operation before and after the plant design step. Also, it is expected to be helpful for understanding the dynamic behavior of processes under various conditions. For these reasons, we have developed the dynamic simulation model for MSF using GSE's commercial package. The reference model is the Shuaibah IWPP MSF of 16.2 MIGD unit capacity (about 73,600 ton/day) in Saudi Arabia. The results showed that the simulation model was virtually stable at 100% load in summer condition with 5% deviations of designed values. In the dynamic simulation of start-up procedure, simulated trends were proven to be realistic based on real plant operation data. These results suggest that the dynamic simulation model could be applied for operator training and trouble shooting of operation procedures. [ABSTRACT FROM AUTHOR]

Techno-economic analysis of a newly developed high performance multistage flash configuration with deaeration and brine mix (MSF-DM) is presented. The techno-economical analysis includes also the use of nanofiltration (NF) as a pretreatment method for MSF to increase its top brine temperature (TBT) to 130°C. A mathematical model of NF membrane is developed and verified using Visual Design and Simulation program for typical operating NF unit (Umlluj, KSA). The techno-economic analysis of integrating NF pretreatment for the existing multistage flash-brine recirculation (MSF-BR) and newly developed MSF-DM configurations is performed. Integration of NF system to existing desalination plant (NF-MSF) and treatment of only 30% of make-up enable to increase the TBT up to 130°C, the production can be increased to 19%. The cost analysis showed the unit product cost is 5.4% higher than that conventional MSF (at 110°C) due to the additional capital cost of NF system. Integrating NF system to new configuration (NF-MSF-DM) desalination plant at the TBT = 130°C, the gain output ratio could be as high as 16, i.e. double the convention MSF-BR. The new NF-MSFDM configuration significantly reduces the unit's input thermal energy to suit the use of (the relatively expensive) solar energy as a desalination plant driver. On the other hand, the levelized water cost of NF-MSF-DM (at TBT = 130°C) is 14% lower than conventional MSF (at 110° C) at the current oil price 104 $/bbl. [ABSTRACT FROM AUTHOR]

The term availability can be defined as the probability of a system or piece of equipment, when used under the specified conditions, operates satisfactorily at any given time. The availability of the equipment installed in a seawater reverse osmosis (SWRO) facility is extremely important to the price, quality, and quantity of the final product--water. There are three critical components in the SWRO processes; the main high-pressure feed pumps, the reverse osmosis (RO) membranes, and the energy recovery device (ERD) system. The role that ERDs play is undeniably critical to the success or failure of an RO facility's ability to produce and deliver water economically. The largest operating expense for an SWRO facility is the power consumed, which accounts for approximately 30% of the total RO operating expense. Typically for large facilities (>50,000m³/d), the ERDs responsible for reducing energy consumption are only 1-2% of the entire initial capital cost-a small fraction-but one that can offer a substantial return on investment through energy savings. Selecting the proper ERD system can save millions of dollars over the life of a plant and provide owners and operators with a secure and reliable means of water production. This paper will focus on the economic benefits and importance of the availability of ERDs in SWRO desalination plants. [ABSTRACT FROM AUTHOR]

In recent years, the size of reverse osmosis plants has increased dramatically. The layout of many plants has also changed, incorporating a center design. The advantage of this design is that the membrane feedpumps discharge into a common header, and the output of the pump is no longer linked to the flow for a specific rack of membranes. This has allowed the use of much larger pumps in a two- or three-stage configuration. The use of larger pumps improves the unit efficiency while lowering the installation costs by reducing the number of pumps. Pump manufacturers continue to strive to improve the efficiency of these pumps by modifying and upgrading the basic design. The horizontal split case design has been manufactured for more than 80 years. In the last 5 years, the efficiencies of this design have been improved substantially, thereby lowering the operating costs of the desalination plant. A paper was presented earlier outlining the role of the suction impeller and suction bay design. This paper will detail the hydraulic optimization that has been applied to maximize the efficiency. [ABSTRACT FROM AUTHOR]

Multi-effect distillation (MED) desalination with thermal vapor compressor (TVC) is widely used in a dual-purpose power plant configuration. Due to the variety of extraction pressure and water demand, it works under a wide range varying from over-rated load to less than half-rated load. The adjusting method of load performance is presented to obtain the optimal performance of MED-TVC desalination plant based on the operating characteristics of TVC and MED. With adjustable TVC, the thermodynamic performance of MED-TVC is analyzed when water load and extraction pressure varies. The effect of the variation in feed seawater flow rate, together with the heating steam temperature of the first evaporator, is also investigated. The results of the analysis are fairly close to the data of a practical MED-TVC plant, which justifies the expectation that the analytical method is accurate and reliable. [ABSTRACT FROM AUTHOR]

Of paramount importance, seawater desalination plants using reverse osmosis (RO) is reducing the use of energy, which is mostly required for high pressure pumps. Accordingly, energy recovery devices (ERDs) are widely used for reusing hydraulic energy in RO concentrate stream. Nevertheless, few works have been done to investigate the operation characteristics of various EDR systems in actual desalination plants. In this context, we focused on the comparison of ERDs in a pilot plant with the capacity of 1,000m3/day. One centrifugal ERD (turbocharger) and two different types of isobaric ERDs (pressure exchanger [PX] and pressure exchanger for energy recovery [PEER]) were installed and tested under various conditions. Operation data in the pilot plant were analyzed to estimate specific energy consumption and energy transfer efficiency. The specific energy consumption analysis results showed that the isobaric ERDs have higher efficiency than the centrifugal ERD as also expected in theoretical estimation. The energy transfer efficiencies for PX and PEER were determined to be similar in short-term tests. [ABSTRACT FROM AUTHOR]

Colonization of cooling water systems (CWS) by fouling organisms is a major concern for industries, power, and desalination plants over the world. Biofouling results in, depending on the dimensions of the biofouling species and growth patterns, an increased wall roughness and reduction of the inner pipe diameter. This leads to a significant head loss in the intake structure. To prevent settlement and growth of fouling species, an effective antifouling treatment is required. However, fouling mitigation must be applied from early start of operation of an installation, as several species cannot be fully mitigated (chemically) or removed (physically) after settlement, as some of them (e.g. barnacles, the Japanese oyster and Rock oyster) cement themselves to the surface. This means that even after a physical cleaning, part of the organisms remains on the surface, resulting in an irreversible increased head loss and a decreased pump capacity. To provide some clearance on the impact of biofouling on pump capacity in CWS, two cases have been studied. The results show that nonoptimal fouling treatments result in significant additional annual energy consumption. Even after complete physical cleaning, the remaining head loss is above the design line due to the increased wall roughness and results in decreased pump capacity. The results strongly emphasize the necessity to apply an effective biofouling control during the start-up of a water intake system prior to commercial operation, or to have system design parameters which take into account the irreversible effects of biofouling. [ABSTRACT FROM AUTHOR]

In this paper, the results of the complete life-cycle assessment (LCA) analysis of the water cycle in two Spanish urban areas are presented. First case study was Zaragoza city (700,000 inhabitants), with enough surface water resources for drinking purpose. Second case was the Mancomunidad del Sureste, a highly populated and touristic area in a water-scarce island (Gran Canaria). Main objective of the paper was to show, from an environmental global perspective, which was the relative pollutant weights of the diverse water cycle stages in an urban area, in order to put the efforts in reducing the environmental penalties associated to the water cycle. Results showed that environmental load associated to energy consumed in dwelling uses (to produce hot sanitary water) exceeded by far the environmental impact provoked by water cycle infrastructures (water treatment plants, water supply and drainage networks, and wastewater treatment plants). Additionally, it is very important to remark that new water supply alternatives (seawater desalination plant as well as reclaimed wastewater) studied here were energy intensive solutions, and the environmental charge during its life cycle was also very significant. [ABSTRACT FROM AUTHOR]

Okinawa Island is located in the southern region of Japan and has a population of 1.22 million. Okinawa Prefectural Enterprise Bureau (OPEB) supplies 410,000m³/d of water to 24 municipalities. Although OPEB uses multiple water resources including dam reservoirs and groundwater, increased water demand resulted in occasional water shortages until a seawater desalination plant (40,000m³/d) started operations in 1997. In this study, a model was developed to simulate the water supply system of Okinawa Island using precipitation and OPEB operational data from 2009 to evaluate the role of the desalination plant in reducing risks associated with drought and power consumption of the plant. The simulation results indicate that without the desalination plant, the dam reservoir storage falls below 50% for 70 days, whereas with the desalination plant, storage remains above 50%. If the plant was operated at full capacity, the dam reservoir storage increased by 17.2% after 1 year of simulation time. However, the desalination plant consumes 4.5-14.7 times more electricity per unit volume of water than other water resources. Although the desalination plant plays an important role in avoiding water shortage in Okinawa Island, operational protocols to minimize power consumption need to be developed further using simulation models such as the one developed in this study. [ABSTRACT FROM AUTHOR]

In the building of marine brine discharge pipelines from desalination plants, there are some technical and environmental conditions that require previous numerous studies to guarantee their viability. In the project of Águilas desalination plant with a production capacity of 180.000m³/day, in Murcia, Spain, a marine emissary was designed. It was made up of various sections that entail different building complexities. The main difficulty was to build a tunnel in the rocky massif called "Peñon del Roncaor"; the tunnel was dug through a piling of 443m of length and an exterior diameter of 2.400mm that would have come up at a depth of 12m to join the submarine section of 290m of length. These more detailed geotechnical studies showed a great heterogeneity in the composition of the materials to be excavated from the Peñon. In order to avoid any risk of affecting to the castle right above considered of cultural interest, a new tracing of the tunnel was designed. The new tracing runs the Peñon's outer south borders right into the dumping area. This new tracing implies greater length of piping and greater seabed marine area occupation as well; it required carrying out additional bionomic studies to guarantee its environmental compatibility. We must bear in mind that the marine surroundings of Águilas are a protected area included in the Red Natura 2000 (LIC Submerged Costal Strip of the Murcia Region) whose predominant bionomic community is the Posidonia oceanica beds, limited to the Southwest by another less dense seagrass of Cymodocea nodosa. These seagrass meadows and rock communities suffer anthropic pressure for its proximity to the city of Águilas, as near-shore marine discharges, fishing activity, and others. And, there are other affections of natural condition: terrigenous sediments and nutrients that get to the dry riverbed name El Charco, having seriously affected the species of greater natural value and the implementation of those ubiquitous species, and thus impoverishing habitat in general. Due to the fact that P. oceanica seagrasses have very low tolerance to increased salinity in the western Mediterranean Sea; a hydrodynamic model was developed to estimate the likely dilution of the brine discharge for this new solution. Other works comprise a bathymetric survey to establish the profile of the ocean bottom--very important for pipeline construction--a sediment characterization, the study of the oceanographic conditions and a monitoring study of the marine water quality to settle the values of the water quality in the preoperation moment and the parameters needed for process designing. During the construction of the pipeline, an environmental surveillance program was developed. And at the end of the stage, a study was developed to know the impacts produced by the works carried out and to establish the "zero situation" before start of the operation phase. In addition to that, a very strict environmental legislation was applied along the process. These regulations included exhaustive and systematic controls of several environmental parameters when starting and during the plant operation. [ABSTRACT FROM AUTHOR]

Desalination in Spain has a long story. From the early 60s many installations for drinking water supply were built, mainly in the Canary Islands. Soon it was assumed that other users would need water supply at competitive prices. Agriculture was one of them. The leap from the islands to mainland was in the 90s, when there was a substantial water shortage. In this decade, more than 200 installations were built for this application, mainly treating brackish water. More recently, the installation of large capacity plants from Spanish government programme "AGUA" would mean the end of small plants for agriculture although a discussion about the price for desalinated water arose between the government and the agricultural users. In this paper, we will describe the Spanish experience in desalination for agriculture from an historic point of view. We will also discuss the economic aspects such as the price of water obtained from desalination plants compared with other sources such as superficial or reused water as well as the percentage of water costs in agriculture production and other beneficial aspects such as increased production. With the experience gained for more than 17 years and 60 different size installations built, this paper will be illustrated with some examples where farmers have built their own desalination plants. Another interesting aspect will be to show how to do the planning for an irrigation system for agriculture based on desalination. [ABSTRACT FROM AUTHOR]

Kuwait is a major oil producer in the Middle East with an oil production reaching three million barrels/day. The increased oil production will certainly result in more produced water that requires handling and treatment. The full picture of the produced water and its impact on the environment is yet to be fully realized due to the lack of data available on produced water characterization. In this paper a review of published work on the characterization of Kuwait oil-produced water is presented. From the review of published data there is clearly a big gap in the physical and chemical analysis of produced water. The choice of treatment methods considered and implemented was limited and driven primarily by economics, with little consideration to the environment. There was considerable research and data published on the environment mainly on the pollution of coastal regions from desalination plants and other causes, but hardly on the effect of produced water. Scarcity of water is a real issue acknowledged in the reviewed literature; however the consideration of recovering and treating produced water for domestic consumption and irrigation is yet to be realized. Finally, recommendations are proposed for handling and treatment of produced water taking into consideration future industrial development, environment and new treatment technologies available. [ABSTRACT FROM AUTHOR]

We introduce the present article with the intention to define the most efficient production line for reverse osmosis seawater desalination plants. We show the relationship between the cost of desalinated water per cubic meter according to the production capacity, verifying a scale economy as the production rises significantly. The destination of this article is within the reach of small desalination plants in the range between 500 and 15,000 m³/day in the Canary Islands Autonomous Community. Specified range is the most established in the Autonomous Community. Approximately, more than about the 90% of the desalination plants have a production capacity corresponding to the selected range. The methodology used consists of calculating each one of the costs involved in the seawater desalination process, applying actual prices, and obtaining a graphic serial according to prices tolerance, from -5% to a value of +5%. Concerning staff costs, we have recovered data from the iron and steel industrial sector collective agreement of the Autonomous Community. In our article, we present all the elements that directly affect each one of the costs, equations, and formula based on factors affecting each one of them, with actual market prices in the Autonomous Community of Canary Islands, making all calculations and obtaining a family of costs graphics for each one. As an innovative and original article, we present the real costs for small desalination plants, in between the said range. We also present a new cost, to bear in mind, according to current regulations, which is the environmental cost, based, among other things, in solving the problem of brine spills directly into the sea. Cost has been calculated based on the introduction of a new machinery and canalization to reduce the before mentioned environmental impact. Lastly, this article, as a final result, presents the total value of the cost in €/m³ with the results and graphics for each plant between the before established range in the Canary Islands, obtaining according to them, the most efficient production line. We present the results based on a small fluctuating scale economy. Our article presents costs results in order to be able to select the most convenient production line in each case, based on the production capacity and on the several own factors of each individual cost. The aim of our work is to study the influence of the fouling factor and temperature according to the desired production (500-15,000 m³/day) on the cost in €/m³. Based on it, we study the operational and functional costs searching for the production line with the best efficiency. [ABSTRACT FROM AUTHOR]

Most countries in the Middle East & North Africa (MENA) region currently face water scarcity and rising water demand. In order to respond to these challenges, many MENA countries proceed to the use of desalination. As desalination processes are highly energy-intensive, the use of conventional energy for the operation of desalination plants contributes to climate change through greenhouse gas emissions, with negative impacts on the water cycle. The use of renewable energy sources to supply desalination plants with electricity can be a more sustainable and environmentally friendlier option to bridge the water demand gap. The present paper outlines the main barriers to desalination using renewable energies (referred to in short as 'renewable energy desalination', RED) in most MENA countries, gives an overview of main features of the water and energy policies in the MENA region, and compares them to the framework conditions in Australia or Spain. Supportive policy approaches to overcome the existing barriers and to promote RED are highlighted. The paper advocates the importance of adopting a more consistent legal framework to foster the deployment of RED and thereby reduce the effects of climate change and water scarcity. [ABSTRACT FROM AUTHOR]

The operation and maintenance of a seawater desalination plant have many challenges. One of the major challenges is to ensure the economic viability while complying with all the terms of the operation and maintenance contract, hence the constant quest for cost savings. One area for potential improvement is to rethink or optimize the use of chemicals and in particular the use of sulphuric acid. Sulphuric acid is used to lower the pH of feed water in order to reduce the risk of mineral precipitation on the reverse osmosis membranes. Simply eliminating sulphuric acid will result in a substantially higher operating pH and an associated increased risk of mineral precipitation. Managing this risk involves the injection of a properly selected high performance phosphonate-based threshold scale inhibitor. This article describes the details of a field trial in a two-pass seawater desalination plant during which sulphuric acid was phased out and replaced by a phosphonate- based antiscalant. The results show that the critical operating parameters remain stable, indicating the successful prevention of scale formation, throughout the trial period during which sulphuric acid was replaced by a phosphonate-based threshold scale inhibitor. A holistic approach was used to understand the full impact of the replacement of sulphuric acid by a phosphonate-based threshold scale inhibitor on the operating costs of this seawater desalination facility. [ABSTRACT FROM AUTHOR]

Reverse osmosis (RO) is a widely accepted and applied process for the purification of a variety of raw water sources, especially when there is a need for removing the bulk of the dissolved salts and other impurities present in the feed streams. Since its first applications and references, the technology has progressively been refined and improved, up to the current mature status, where, even if innovations are still to come, a solid base frame exists already. This paper will review and analyze long-term operation data from medium and large-size projects, including two different seawater desalination plants examples. It will focus on the long-term stable and reliable performances of DOW FILMTEC™ RO elements, by comparing the expected performance to the current operation data, with special emphasis on the long life of elements, and thus low replacement rates. These two installations are of particular interest given the time they have been successfully producing the required amount of drinking water. The paper will also evaluate the existing plant designs and contrast them to plant design modifications that would have been applied if those installations were designed with current membrane element technology. [ABSTRACT FROM AUTHOR]

Qatar has experienced rapid economic growth due to the discovery and production of fuel oil and natural gas (NG). The natural renewable water resources (rainfall and groundwater [GW]) are depleted; and are estimated as 71-m³/per year per capita in 2005. This is far below the water poverty line of 1,000-m³/yca. The GW withdrawal is excessive (compared to replenishment) and is used mainly for irrigation. A very small amount of GW is treated to become potable water and is distributed to consumers. The municipal potable water mainly contains (99%) desalted seawater (DW) and 1% GW. The consumption of DW and electric power (EP) is continuously rising due to the increase in both population and the standard of living. The population have been more than doubled from 2000 to 2010. The DWis produced in power plants generating both EP and DW, and is called Cogeneration Power Desalting Plants (CPDP). These CPDPs are using either: simple gas turbines (GT) cycle or GT combined with steam turbine (ST) to form a GT combined cycle (GTCC). A thermally driven multi-stage flash (MSF) desalting system is mainly used to desalt seawater. LargeMSF units are operated in the CPDP to get their thermal energy (as steam) needs either from: (i) heat recovery steam generators coupled with GT or (ii) steam extracted or discharged from the ST of the GTCC. The CPDPs consume large amounts of fossil fuel (FF), mainly NG. The burning FF pollutes the environment by emitting the carbon dioxide (CO2), carbon monoxides, and nitrogen oxides (NOx). The CO2 and NOx are greenhouse gases causing global warming. Raising the effi- ciencies of EP and DW production can reduce their negative impact on the environment. The sustainability of water in Qatar is questionable: the extracted GW is several times its replenishment rate. The municipal water supply depends almost on desalting seawater by MSF, which is energy intensive and costly process. Deploying a more energy-efficient desalting system such as Seawater Reverse Osmosis systemcan save a lot of NG, the nation's main source of income. The use of treated wastewater (TWW) is limited to some agriculture and landscaping. The ratio of TWW to municipal water supply is low, about 25%. It is also essential to promote conservation measures for both water and power. This paper reviews the water profile in Qatar and recommends solutions to solve the growing water scarcity in Qatar. [ABSTRACT FROM AUTHOR]

Barcelona-Llobregat Desalination Plant is actually the largest seawater desalination plant in Europe producing potable water from the seawater of the Mediterranean Sea. The plant is able to supply approximately the 20% of tap water of Barcelona Metropolitan area having a maximum capacity of 200,000 cubic meters per day. This project was developed by Aigües Ter-Llobregat, public company of the Catalonian Government (Generalitat of Catalonian) to face the lack of water resources and to improve the water quality in Barcelona's south area. A Joint Venture of Degrémont, Aigües de Barcelona and Dragados-Drace built the plant during a severe drought period in a extremely tight delivery time of 24 months. The plant was inaugurated on July 2009 and from this date the same JV is operating it. Barcelona-Llobregat SWRO plant won the Global Water Awards 2010 as the Desalination Plant of the year. A pilot plant was operating for two years to help in design and for getting experience with Mediterranean seawater. The facilities are located in El Prat, an industrial area between Barcelona Harbour and Llobregat mouth, just close to one of the waste water treatment plants of Barcelona, DepurBaix. A deep intake located 2 km offshore feed the plant avoiding the Llobregat river impact, especially for heavy rain period, and the harbour leaks. Sea water is pumped for more than three and a half km, crossing the river through an underground pipe. A very strong pre-treatment protect reverse osmosis (RO) membranes: a set of 10 SeaDAF®, high speed floatators, is the first step followed by 20 Mediazur® gravity filters and 20 SeaClean® pressurized dual media filters. The polishing is guaranteed by 18 cartridge filters of 5 microns. The silt density index15 of pretreated seawater is always below 3.0%/min, with an average of less than 2.5. Ten RO trains with a unitary production over 20,000m³/day are fed by individual HP pumps and the energy recovery is assured by a set of 23 PX220 per train. A partial second pass guarantees a boron concentration in treated water below 1.0 mg/l (two trains of 16,500m³/day). Remineralization is made with CO2 and upflow limestone filters with an innovative design. Potable water is pumped over 12km to Fontsanta reservoirs to be blended with waters coming from two potable water plants, one with electrodialysis reversal treatment. Brine have an innovative treatment: it is blended with treated water from DepurBaix waste water treatment plant in a ratio lower than 1:1 and discharged through diffusers at 50m depth to more than 3 km from intake. All effluents are treated before discharge and the plant has sludge treatment. The plant has increased the "green label" adding a wind generator and photovoltaic panels in the building roofs to minimize the electric internal consumption. The operational criteria and managing water production is another important chapter, because it takes into account all available resources. The paper will describe: - several innovative details of the plant and the construction; - the construction and operation feedback; - the criteria to decide the production of the plant; - the follow-up of main parameters of seawater and plant; - the real energy consumption in the different stages; - results of pre-treatment, RO trains and post-treatment from the first two years of operation; - and the integration of the plant in the regional water supply system, considering the principal factors * Volume storage in the dams. * The operation of the drinking water plants. * The pluviometry and the climate predictions. * The regional water supply planning.The rest of the available resources (ground water, etc.). [ABSTRACT FROM AUTHOR]

Israel's master plan for integrating large-scale seawater desalination plants within the national water supply system was drafted in the year 1997. This master plan sought not only to minimize the costs of these additional water sources, inter alia through plant siting, economies of scale, and maximizing utilization of existing infrastructures, but also to maximize their benefits. Some of the benefits, particularly those resulting from higher product water quality requirements, justified, on a cost-benefit ratio basis, corresponding slight increases in the costs of desalinated water production. At the end of 2011, desalinated seawater was supplied continuously and reliably into the regional and national water grids from three large plants, Ashkelon, Palmachim, and Hadera, at the rate of about 300 million m³/year. This quantity represented about 42% of all the potable water inputs into these grids (other inputs were groundwater and Sea of Galilee water). In three years, by the end of 2014, two additional large plants, at Soreq A and Ashdod, and an expanded Palmachim plant will be producing an additional 300 million m³/year. The paper revisits the benefits foreseen in the original desalination master plan, quantifies them on the basis of actual data accumulated over the past year and some new studies on the economic effects of water shortages and water supply quality, compares them with past expectations, and projects them to 2014, when about 80% of grid supplied water will be desalinated seawater. [ABSTRACT FROM AUTHOR]

The Al Dur Power & Water Company is a 2.1 billion USD gas-fired greenfield power generation and seawater reverse osmosis desalination plant that is located on the southeast coast of Bahrain. The company Degrémont has been selected to design and build the Reverse Osmosis (RO) desalination plant, for a drinking water production capacity of 218,000 m³/day. The plant design had to answer to particularly challenging requirements, both for the pre-treatment and for the posttreatment steps. The pre-treatment step is one of the key factors for the success of desalination using the reverse osmosis process. Its purpose is to remove the major foulants, which can be found in the seawater to allow for a reliable operation of the reverse osmosis units. It is even more essential within the Gulf area, where the seawater contains high concentrations of organics and is subject to algal blooms. Al Dur RO plant was thus designed with an efficient two-step pretreatment process: a flotation step, including an enhanced coagulation stage, and a filtration step. In parallel, to assess the seawater variability and demonstrate the performances of the selected pre-treatment line, a pilot study was carried out on-site during one year. Al Dur drinking water objectives were particularly challenging and the design had to incorporate unusual guarantees such as a Silt Density Index below 3.0%/min, a turbidity below 0.2 NTU and a Langelier Saturation Index between 0.1 and 0.3. As a consequence, to comply with both the Bahraini drinking water standards and the tender specifications, the Al Dur mineralization unit design included a high velocity lime water saturator and a lime water filtration unit. The present paper describes the pre- and post-treatment performances based on the initial project design, the pilot study and the on-site results during the commissioning and the first few months of operation. [ABSTRACT FROM AUTHOR]

Water is an important component in the mining industry. With mines often located in remote and dry areas, a sustainable supply of water is crucial. The development of seawater desalination, reduced membrane costs, and reduced energy consumption have made seawater a viable source of water supply for mining. Reliability of the desalination plant, quality of the water, and the availability of sufficient water supplies are the most important requirements to be ful- filled for the mining industry. Therefore the best available and proven technologies meeting the above-mentioned criteria should be used. The key for successfully operating a seawater desalination process based on reverse osmosis membranes (SWRO) is the pretreatment. Several tests conducted by researchers all over the world have proven that ultrafiltration (UF) provides an optimum pretreatment for the SWRO. The UF removes all the suspended solids and provides a substantial reduction in the microbiological activity. The plugging in of SWRO spacers is completely eliminated and the SWRO cleaning frequency can be drastically reduced. This paper presents the experience of using the UF as a pretreatment to the SWRO in Chile. Two desalination plants are described. Both the plants are of the desalination type dual membrane: ultrafiltration followed by reverse osmosis. One plant (GasAtacama) was commissioned in June 2011 and has since been successfully in operation. The second plant (Minera Candelaria) is currently under construction. [ABSTRACT FROM AUTHOR]

Brine discharges from desalination plants spread out over broad spatial scales, affecting the benthic communities encountered along the way. Because of this, it is essential to develop technology enhancement initiatives for brine discharge processes that are economically feasible and effective for both planned and existing desalination plants. The technical feasibility of using venturi diffusers rather than conventional devices to enhance dilution processes was studied at the Maspalomas II desalination plant, in the south of the island of Gran Canaria (Canary Islands-Spain). The venturi eductors needed very high exit velocities (≥11 m/s) to reach the pressure difference required to produce the suction effect of these devices. At these velocities, the venturi eductors were more efficient than conventional diffusers, as they achieved much higher dilutions of around 39 as opposed to 27. Dilutions as high as these are not only very useful, but also necessary, as part of the island's largest and most ecologically important seagrass meadow of Cymodocea nodosa is found nearby. [ABSTRACT FROM AUTHOR]

The most likely environmental impact of concentrate discharges (in most instances twice the concentration of the ambient environment) leaking from desalination plants on local marine ecosystems has been controversially discussed for many years. Increasing water demand and lack of renewable natural water resources in Saudi Arabia also result in greater dependence on desalination and consequently amplify the impact on marine environment and multifactorial ecosystems in near-field areas of desalination discharges. Accurate scientific baseline data should furnish information on various factors such as intake- and outfall locality, brine (concentrate) discharge and chemical characteristics (i.e. effluent concentration, mass flow rates (flux)), local effects, and even cumulative effects of desalination activities, at least on a regional and even on a national scale. Even if such data were available, in many cases they are non-transparent and are not even accessible, or tend to be overlooked as a result of ambiguous desalination-related policies. This paper focuses on national environmental regulations in the Kingdom of Saudi Arabia (KSA) and how such regulations help control the flow of concentrate discharge into the receiving waters. [ABSTRACT FROM AUTHOR]

Seawater desalination is currently considered a vital and dependable water resource to meet all requirements of fresh water. Kuwait has been a leading country in fresh water production from the sea using the multistage flash (MSF) unit. All MSF plants in Kuwait are operated on the principle of chemical additives dosing for scale inhibition, and at a top brine temperature below 120°C. This is because calcium sulfate scaling phenomenon usually occurs when the temperature is higher than 120°C. This type of scaling is a hard scale that cannot be removed easily by chemical or mechanical cleaning. Until recent years, no antiscalants could overcome this type of scaling at high temperatures. The new generation of antiscalants is able to stand high operation temperature without hydrolysis or without losing their reactivity and can solve sulfate scaling problem. This paper consists of laboratory tests to evaluate the performance of new inhibitors that can overcome sulfate scaling. In particular, experiments were conducted to study the antiscalants effectiveness under different operating conditions with different brine concentration, especially in high-temperature operation mode. The result of the experiment showed that the performance of these chemical additives varied with the operating temperature, flow rate, and the brine concentration. The tested chemicals showed reduction in the percentage precipitation at high temperature up to 160°C. A techno-economic feasibility study was also conducted. [ABSTRACT FROM AUTHOR]

Ultrafiltration (UF) membrane provides an effective means of removing particles and microbial contaminants by size exclusion with the requirement of smaller footprints with conventional pretreatment processes. Although a few works have been done to optimize UF membrane modules and systems for drinking water treatment and membrane bioreactor (MBR), little information is available on UF design for pretreatment of seawater/brackish water desalination. This study focuses on the design of hollow fiber UF membrane modules for pretreatment processes in desalination plants. A theoretical model was developed and applied to predict the filtration efficiency of hollow fiber UF membranes. Typical conditions for pretreatment of feed solution to reverse osmosis desalination were considered. The effect of module dimensions and fiber packing density on pressure drops was also analyzed using the model. It was found that fiber thickness and module size are important as well as inner diameter and length of the fiber. [ABSTRACT FROM AUTHOR]