Large-scale Desalination Plants Research Articles

Resources optimization using Pareto analysis for sea water desalination plants

This study examines the potential of implementing a systematic approach to piloting desalination plants, with the objective of evaluating energy improvements in water desalination processes. The introduction of new reverse osmosis membranes is imperative at the small-scale level. The findings can be extrapolated to inform the operation of large-scale desalination plants. The objective of this approach is to achieve the optimal water quality standard at the lowest possible cost. In this manner, pilot tests are being conducted prior to the determination of whether to alter the reverse osmosis membranes, as this represents a substantial investment. The objective of these tests is to minimise the risk of making an erroneous decision and to ensure optimal results in terms of energy consumption, operating costs and reduction of environmental impact, while complying with the requisite water quality standards. In this instance, the Pareto analysis is utilised to ascertain the two or three most significant causes whose treatment affects more than 80 % of the potential energy savings to be implemented. This article introduces a novel approach to studying a total of 180 desalination plants at the territorial level in the Canaries.

Design of a Novel Heliostat for a Large-Scale Desalination System

The optical design and the mechanical structure of a new heliostat is described for application in the Solar Water plc large-scale desalination plant, to be constructed in the Middle East. The heliostat field is required to reflect direct solar radiation onto a section of the desalination dome, requiring the design of a new type of heliostat. A novel dual-tilted dual-axis tracking heliostat is the design selected to meet the optical requirements specification. The supporting structure also requires a unique approach, which we describe in this paper. The optical and mechanical analysis of the heliostat and its operation are also presented.

Optimization of sustainable seawater desalination: Modeling renewable energy integration and energy storage concepts

Many arid and semi-arid regions of the world face growing freshwater scarcity, requiring increased utilization of seawater desalination to augment the existing freshwater resources. Seawater reverse osmosis (RO) is currently one of the most deployed technologies, due to its electrical energy efficiency and comparatively low costs. However, the required energy for desalination processes is often still converted from fossil sources. Given the growing demand for seawater desalination and the energy sector’s parallel decarbonization, the substitution by renewable energy sources (RES) is a critical issue. The volatility, lower availability of renewable energy, and cost for required electrical energy storage (EES) are all obstacles to the decarbonization of large-scale desalination plants and may affect production volume and water production costs negatively.This paper presents a mathematical model to determine a cost-optimal energy conversion and EES mix for the design and operation of large-scale seawater RO desalination plants. The linear program ensures satisfaction of the plant’s energetic demands. Furthermore, the model allows to investigate the general feasibility of integrating RES into large-scale desalination processes, which are examined by means of a case study while employing location-specific weather data. Different types of energy conversion technologies and the effect of EES on operating behavior, greenhouse gas emissions, and water unit costs are investigated. Specifically, the indirect storage of electrical energy via the smart management of a desalination plant’s oversized RO membranes is examined and compared to battery energy storage (BES).Results indicate that RES cannot meet an RO desalination plant’s full and constant electrical load demand without a high BES capacity, which is probably not feasible from a technical and economic point of view. The economic penalty from energy storage costs on one unit of desalinated water ranges from 3.10 $/m3 up to 5.38 $/m3. However, operating an oversized RO desalination plant intermittently could reduce the energy-related costs substantially and potentially provide a more appropriate way of adapting to a volatile supply of energy from renewable sources in order to decarbonize the desalination processes. Specific emissions of desalinated water can be reduced from 1.5 kg CO2 eq./m3 when relying mostly on combined cycle gas turbines down to 0.124 kg CO2 eq./m3 by intermittent operation and fully relying on renewable energy sources.

Mega-scale desalination efficacy (Reverse Osmosis, Electrodialysis, Membrane Distillation, MED, MSF) during COVID-19: Evidence from salinity, pretreatment methods, temperature of operation

The unprecedented situation of the COVID-19 pandemic heavily polluted water bodies whereas the presence of SARS-CoV-2, even in treated wastewater in every corner of the world is reported. The main aim of the present study is to show the effectiveness and feasibility of some well-known desalination technologies which are reverse osmosis (RO), Electrodialysis (ED), Membrane Distillation (MD), multi effect distillation (MED), and multi stage flashing (MSF) during the COVID-19 pandemic. Systems’ effectiveness against the novel coronavirus based on three parameters of nasopharynx/nasal saline-irrigation, temperature of operation and pretreatment methods are evaluated. First, based on previous clinical studies, it showed that using saline solution (hypertonic saline >0.9% concentration) for gargling/irrigating of nasal/nasopharynx/throat results in reducing and replication of the viral in patients, subsequently the feed water of desalination plants which has concentration higher than 3.5% (35000ppm) is preventive against the SARS-CoV-2 virus. Second, the temperature operation of thermally-driven desalination; MSF and MED (70-120°C) and MD (55–85°C) is high enough to inhibit the contamination of plant structure and viral survival in feed water. The third factor is utilizing various pretreatment process such as chlorination, filtration, thermal/precipitation softening, ultrafiltration (mostly for RO, but also for MD, MED and MSF), which are powerful treatment methods against biologically-contaminated feed water particularly the SARS-CoV-2. Eventually, it can be concluded that large-scale desalination plants during COVID-19 and similar situation are completely reliable for providing safe drinking water.

Agriculture Drought Management in Ramanathapuram District of Tamil Nadu, India

Drought is one of the recurring features of Indian agriculture, especially in the rain fed areas. It affects not only the national food security but also causes miseries to human life and live stock. The study area, i.e., Ramanathapuram district of Tamilnadu, India (Latitude 9°40′and Longitude 78°70′) has been affected consecutively for the last three years from 2015 to 2018 by drought, due to the failure of rainfall of northeast and southwest monsoons. So, the economic status of the area has declined due to the drought and the people from this district have migrated to other districts to improve their socio-economic status. This district has seven taluks, eleven blocks and four hundred villages. Major physiography units of the district are vast coastal plain, adjacent alluvial plain and a small area of buried pediments. The predominant geological formations are recent alluvium, and laterite followed by mio-pliocene Cuddalore Sandstone, upper cretaceous calcareous sandstone and proterozoic basement rocks. The total thickness of sedimentary rocks may be upto 3000 metre. The shallow aquifer in the district is severely affected by sea water intrusion and the inland salinity of marine sedimentary formations. Since the shallow aquifer is saline, paddy cultivation practices are generally being done through rain fed lake irrigation. According to the Central Ground Water Board report, the deeper groundwater aquifer in this district would give a continuous supply of freshwater. In order to develop agriculture activities and avoid drought management, the following steps are to be undertaken immediately. 1. River linking scheme of westerly debouching, i.e., Western Ghat Rivers in the Arabian Sea with the ephemeral rivers of the study area such as Vaigai, Gundar and Kottakkarai Rivers to improve the recharge of groundwater and prevent sea water intrusion. 2. Delineation of the depth of deeper fresh water in Tertiary and Cretaceous aquifer by sub-surface mapping study through 2D resistivity imaging depth profile study and borehole data. 3. Augmentation of engineering structures in the coastal area will prevent sea water intrusion in the shallow aquifer. 4. To improve the socio-economic status of the farmer and for drought management, a crop insurance scheme should be implemented for farmers. 5. Providing long term loans with subsidy facilities should be implemented for the construction of bore holes to improve crop production by getting fresh water from a deeper aquifer. 6. The study area is located nearer to the sea, so the large scale desalination plant system should be implemented by government organisation to get fresh water for improving agriculture practices.

Stand-Alone Direct Current Power Network Based on Photovoltaics and Lithium-Ion Batteries for Reverse Osmosis Desalination Plant

Plummeting reserves and increasing demand of freshwater resources have culminated into a global water crisis. Desalination is a potential solution to mitigate the freshwater shortage. However, the process of desalination is expensive and energy-intensive. Due to the water-energy-climate nexus, there is an urgent need to provide sustainable low-cost electrical power for desalination that has the lowest impact on climate and related ecosystem challenges. For a large-scale reverse osmosis desalination plant, we have proposed the design and analysis of a photovoltaics and battery-based stand-alone direct current power network. The design methodology focusses on appropriate sizing, optimum tilt and temperature compensation techniques based on 10 years of irradiation data for the Carlsbad Desalination Plant in California, USA. A decision-tree approach is employed for ensuring hourly load-generation balance. The power flow analysis evaluates self-sufficient generation even during cloud cover contingencies. The primary goal of the proposed system is to maximize the utilization of generated photovoltaic power and battery energy storage with minimal conversions and transmission losses. The direct current based topology includes high-voltage transmission, on-the-spot local inversion, situational awareness and cyber security features. Lastly, economic feasibility of the proposed system is carried out for a plant lifetime of 30 years. The variable effect of utility-scale battery storage costs for 16–18 h of operation is studied. Our results show that the proposed design will provide low electricity costs ranging from 3.79 to 6.43 ¢/kWh depending on the debt rate. Without employing the concept of baseload electric power, photovoltaics and battery-based direct current power networks for large-scale desalination plants can achieve tremendous energy savings and cost reduction with negligible carbon footprint, thereby providing affordable water for all.

Techno-economic assessment of solar energy coupling with large-scale desalination plant: The case of Morocco

This paper examines the cost competitiveness of an extra-large-scale (275,000 m3/d) solar-powered desalination, taking as a case study the Chtouka Ait Baha plant in Morocco. It assesses the conditions at which solar Photovoltaics (PV) and Concentrated Solar Power (CSP) would be competitive with a grid (mainly fossil) driven desalination plant for the reference year and by 2030. The paper considers also a scenario where battery storage complements PV power generation. To conduct the analysis, a simple model of water cost calculation is built. Second, the cost related to energy consumption is calculated for different power supply options to evaluate the impact of energy provision cost on the final cost of water. The first main result of this paper is that desalinated water can be obtained at an acceptable cost of around 1 $/m3. The second one is that PV without storage remains the cheapest power supply option today and by 2030. Storage based solution appears less competitive today but can be more attractive in a framework of increasing electricity grid prices and higher flexibility requirements in the future. The paper gives recommendations regarding the implication of different technology choices in the framework of the future Moroccan energy system.

Comprehensive techno-economic analysis of integrated nuclear power plant equipped with various hybrid desalination systems

Recently, the development of integrated nuclear power plants (NPPs) for electricity production and seawater desalination has generated considerable interest among researchers. For the past ten years, there has been a rapid rise in the thermo-economic assessment of using nuclear power to supply the required energy for large-scale desalination plants (DPs). Despite all the conducted efforts to increase the reliability of nuclear desalination plants (NDPs), many governments are still reluctant to use them because of safety considerations. Economic benefits and high-efficiency of the co-generation system are the most significant factors that can persuade governments to implement NDPs. With that being said, the major aim of this study is to develop a new computer code to evaluate the economic aspects of various hybrid desalination schemes coupled with NPPs. In this paper after reviewing various aspects of hybrid desalination schemes, the mathematical formulations for evaluating techno-economic analysis are given. The evidence from this study suggests that using the rejected water (hot stream) of the NPP's condenser as the feed water for the DP can be considered as the best option for optimizing the total cost of nuclear desalination.

Economic Assessment of the Possible Desalination Processes for the First Unit of Bushehr Nuclear Power Plant

The problem of ensuring the continuously growing needs of people for freshwater is becoming more acute in Iran. In order to resolve the serious water crisis in arid regions of the country near the Gulf, several desalination units have been used. However, most of the installed units of seawater desalination are based on fossil fuels consumption, which suffers from several disadvantages. According to the demand for clean energy to provide water and electricity, nuclear technology is gaining higher attention as compared to other energy sources. Bushehr NPP as the first commercial nuclear reactor in the country can be included the establishment of a large-scale desalination plant. In this study, after reviewing pertinent aspects of commercial desalination technologies, the history of seawater desalination in Iran is presented. This paper is focused on economic assessment of coupling the Bushehr NPP with different types of desalination systems, namely, Multiple Effect Desalination (MED), Multi-Stage Desalination (MSF), Reverse Osmosis (RO), and RO + MSF, RO + MED (hybrid methods) by using the Desalination Economic Evaluation Program (DEEP) package. By considering the obtained results and advantages of hybrid methods, RO + MED process with thermal/RO ratio of 0.7 and the total capacity of 150 000 m3/day is suggested.

Functional Analysis of Selected Ion Electrically Conductive Hydrogel: Production and Applications in Seawater Treatment

Seawater desalination is becoming a crucial intervention for mitigating water shortage in numerous Middle East countries. Desalination technology is associated with various technological challenges that should be resolved to maintain plant sustainability and performance. For instance, seawater hardness is recognized as a challenge for recent large scale desalination plants. Optional technologies including chemical treatment, adsorption and membrane filtration have been developed for hardness removal and recovery of Ca and Mg. This paper addresses the development and application of a new conductive polymeric hydrogel composite exhibiting electrically tunable characteristics. A comprehensive review on the preparation of conductive hydrogel and its application for water treatment is first presented. The newly developed hydrogel composite comprises treated zeolite, polyacrylate, polyaniline, hydrolyzed polyacrylamide and special processing aids. The characteristics of the composite have been determined via scanning electron microscopy, Fourier transform infrared spectroscopy and electric conductivity measurements in addition to swelling ratio. Impact of composition and processing conditions on conventional and electrochemically enhanced adsorption experiments have been presented and analyzed. Electro-regeneration has been also explored. The promising features of this hydrogel in composite are elucidated by the removal and recovery of hardness causing elements in simulated seawater and brines. It is concluded that the developed hydrogel is initially qualified for upstream seawater softening. Additional endeavors are still needed for downstream brine management to overcome apparent osmotic effects.

Economic Assessment Based on Energy Consumption on the Capacities in Seawater Reverse Osmosis (SWRO) Plant in Korea

Objectives The production cost of reverse osmosis (RO) seawater desalination plant is determined by the CAPEX (Capital expenditure) and OPEX (Operating expenditure). In detail, CAPEX and OPEX are composed of direct cost, overhead cost, electricity cost, and other O&M costs. However, CAPEX and OPEX may vary by country and region. Therefore, this study tries to estimate the production cost by calculating the construction and maintenance costs depending on production capacities based on the operation results such as TDS concentration and the energy consumption from a seawater desalination plant in Korea. Methods A two-stage RO based seawater desalination plant with a capacity of 10 MIGD (45,000 m3/d) was used in this study. The plant consists of a 2 MIGD (9,000 m3/d) unit having DABF (Dissolved air bio-ball filter) and UF (Ultrafiltration) as pretreatment processes, and another 8 MIGD (36,000 m3/d) unit having DABF and DMF (Dual media filtration) as pretreatment processes. To estimate the production cost, construction and maintenance costs were calculated by using GWI's Desaldata cost estimator. CAPEX (Capital expenditure) was calculated based on production capacity, recovery rate, TDS concentration and temperature of seawater, while OPEX (Operating expenditure) was calculated based on production capacity, country, energy consumption, and electricity unit price. Results and Discussion The energy consumptions from EMS (Energy Management System) were 5.48 kWh/m3 at SLC (9,000 m3/d) and 3.4 kWh/m3 at MLC (45,000 m3/d), respectively. In the CAPEX, MLC was reduced by 395,954 ￦/m3 compared to SLC, and the LLC was lower by 192,019 ￦/m3 than MLC. Overall, CAPEX decreased as the production capacity increased. The CAPEX of small plants with production capacity between 10,000 and 50,000 m3/d was significantly different; however, there was no significant difference in larger plants having a capacity above 100,000 m3/d. The OPEX for the annual production capacity showed a sizable difference with 742.3 ￦/m3, 636.5 ￦/m3 and 580.3 ￦/m3 for SLC, MLC, and LLC, respectively. The electricity cost was a substantial portion of OPEX. Also, the production costs based on the interest rates (3% and 5%) were 1,326-1,384 ￦/m3, 1,163-1,209 ￦/m3, and 1,023-1,070 ￦/m3 for SLC, MLC, and LLC, respectively. The results were consistent with 1.0 US$/m3, which is the average production costs presented from other references. Conclusions The production cost estimated using the Desaldata cost estimator based on the CAPEX and OPEX tends to decrease as the capacity increases. However, when the capacity increased over 50,000 m3/d, the production cost decreased by an average of 40 ￦/m3. Thus the decrement of production cost reduced. From these results, the production cost of tap water through seawater desalination was estimated between 1,023 ￦/m3 and 1,070 ￦/m3 above 100,000 m3/d. Therefore, it is difficult to introduce a large-scale desalination plant in Korea, because the average tap water price was 834.6 ￦ in Korea in 2017. However, It is expected that the seawater desalination will be introduced as an alternative water source whenever drinking water price rises, or when the quantity of available drinking water sources reduce due to climate change and water pollution, or whenever energy consumption is reduced as a result of the steady development of the component technologies such as the reverse osmosis membrane, high-pressure pump, and energy recovery device. Key words: Reverse osmosis seawater desalination plant, Water price, Capital expenditure, Operating expenditure, Energy consumption

Development of a multi-criteria decision making approach for sustainable seawater desalination technologies of medium and large-scale plants: a case study for Saudi Arabia’s vision 2030

The process of selecting sustainable desalination technique for a particular application is extremely challenging as the number of available desalination technologies is overwhelmingly high. Every technique stands suitable for many end-user applications such as industrial, community and household activities. However, specific methodologies for selecting the suitable sustainable desalination technology are limited particularly when assessing the requirements of a country composed of many regions with different requirements such as The Kingdom of Saudi Arabia (KSA) which is planned to increase its production from 6.26 to 8.84 million m3 per day (m3/d) from 2017 to 2030. To overcome this issue, this work presents a development and implementation of modified TOPSIS approach, to account for the aggregation effect of the previous selected technology on the next selection of medium and large-scale desalination plants. Total of eighteen independent criteria have been evaluated; six main domains: environment, economy, technical, social, safety and policies and regulations, each has three sub-domain criteria. Parametric study based on actual and projected data of the case study is conducted for different scenarios in order to select the optimum desalination technologies as a function of several variables known to the decision makers such as, production, energy consumption and type of available fuel. The ultimate assessment criterion was the productivity of one barrel of oil equivalent (m3/boe). The study indicated that one barrel of oil equivalent which produces 29 m3 of desalinated water in 2015, shall be capable of producing 86.1 m3 by the end of 2030, through the process of implementation of more advanced desalination technologies.

Coupling pressurised water reactor to large scale SWRO desalination plants: an economic assessment

Water management via rational use, reuse practices and water desalination is the key element for mitigation of water shortage. This paper addresses small-scale nuclear systems as a cost-effective energy alternative for large-scale desalination plants. An empirical cost model has been derived and validated based on reported cost indicators and selected cases. The capital cost of 150,000 m³/d seawater desalination plant coupled to small nuclear reactors has been estimated to be between 3 and 11 M$/MWe, respectively. In addition, specific cost of nuclear desalination-steam cycle system SWRO (conventional pre-treatment), ranges between 0.046-0.064 $/kWh and 0.62-0.667 $/m³ for energy and water, respectively. Cost indicators of different desalination systems show that product water cost ranges between 0.62 and 0.779 $/m³ when applying nuclear power as an energy source for RO, RO/MED, MED while when applying oil/gas as an energy source the product water cost ranges between 1.12 and 1.89 $/m³.

Energetic, Exergetic, and Economic Analysis of MED-TVC Water Desalination Plant with and without Preheating

Desalination is the sole proven technique that can provide the necessary fresh water in arid and semi-arid countries in sufficient quantities and meet the modern needs of a growing world population. Multi effect desalination with thermal vapour compression (MED-TVC) is one of most common applications of thermal desalination technologies. The present paper presents a comprehensive thermodynamic model of a 24 million litres per day thermal desalination plant, using specialised software packages. The proposed model was validated against a real data set for a large-scale desalination plant, and showed good agreement. The performance of the MED-TVC unit was investigated using different loads, entrained vapour, seawater temperature, salinity and number of effects in two configurations. The first configuration was the MED-TVC unit without preheating system, and the second integrated the MED-TVC unit with a preheating system. The study confirmed that the thermo-compressor and its effects are the main sources of exergy destruction in these desalination plants, at about 40% and 35% respectively. The desalination plant performance with preheating mode performs well due to high feed water temperature leading to the production of more distillate water. The seawater salinity was proportional to the fuel exergy and minimum separation work. High seawater salinity results in high exergy efficiency, which is not the case with membrane technology. The plant performance of the proposed system was enhanced by using a large number of effects due to greater utilisation of energy input and higher generation level. From an economic perspective, both indicators show that using a preheating system is more economically attractive.

Performance test of a sea water multi-stage flash distillation plant: Case study

Multi-Stage-Flash (MSF) Distillation is a large scale sea water desalination plants that are widely used in Gulf area. Most installations of MSF plants are operated in cogeneration with a power plant. Also, MSF plants can be combined with other desalination technologies such as Nano filtration and Reverse osmosis (RO) in new installation. However, the new MSF plants are recommended, where large amounts of cheap or waste energy are available (e.g. conventional power plants). Also, the plant location is playing an important role for economic operation due to cold or hot weather conditions.The present study is applied on the seawater multi-stage flash (MSF) desalination plant that is currently under operation in Al-Khafji operations plant located in Saudi Arabia (KSA). The plant contains 20 evaporator stages at capacity of 600,000 gallon per day (GPD). The presented operating data has been collected during a visit of the plant. Theobjectiveis to presentfieldresults of this MSF plant operation in order to measure and evaluate the performance at 70% and 100% capacity during summer (case-1) and winter (case-2) operation. Then, the plant overall performance indicators are presented to compare between the studied two cases in terms of specific cooling water flowrates and performance ratio. Finally, the seasonal performance variation of the plant is included. The results showed that, for the same plant output, the main cooling water flow rates is decreased from 47.1% to 20.1% for case-1 and case-2 respectively, which in turns directly reduces the pumping power by the same ratio. Consequently, running the large scale thermal desalination MSF plant in cold regions is more economic than hot regions for pumping power energy saving considerations. This is to be considered in future large scale desalination plants.

An exergy approach to efficiency evaluation of desalination

This paper presents an evaluation process efficiency based on the consumption of primary energy for all types of practical desalination methods available hitherto. The conventional performance ratio has, thus far, been defined with respect to the consumption of derived energy, such as the electricity or steam, which are susceptible to the conversion losses of power plants and boilers that burned the input primary fuels. As derived energies are usually expressed by the units, either kWh or Joules, these units cannot differentiate the grade of energy supplied to the processes accurately. In this paper, the specific energy consumption is revisited for the efficacy of all large-scale desalination plants. In today's combined production of electricity and desalinated water, accomplished with advanced cogeneration concept, the input exergy of fuels is utilized optimally and efficiently in a temperature cascaded manner. By discerning the exergy destruction successively in the turbines and desalination processes, the relative contribution of primary energy to the processes can be accurately apportioned to the input primary energy. Although efficiency is not a law of thermodynamics, however, a common platform for expressing the figures of merit explicit to the efficacy of desalination processes can be developed meaningfully that has the thermodynamic rigor up to the ideal or thermodynamic limit of seawater desalination for all scientists and engineers to aspire to.

’Biodesalination’: a synthetic biology approach for the use of photosynthetic bacteria in water treatment

Shortage of freshwater is a serious global problem, and expected to become even more urgent over the next decades. Many of the driest regions worldwide are close to the sea, but irrigation of fields with seawater–even if diluted–leads to the build-up of salt levels in the soil that are toxic to all common food crops (http://www.unwater.org). Current desalination technologies such as membrane-based reverse osmosis, are successfully used in large-scale desalination plants, however, they are expensive and energy inefficient [1]. Our multi-disciplinary team of biologists and engineers from 5 UK universities is working on an innovative desalination technology based on biological processes [2]. The “Biodesalination” strategy envisions the use of photosynthetic cyanobacteria modified with light-driven ion transport proteins to function as ion exchangers that selectively remove sodium chloride from seawater. This process would harness solar energy to provide a more cost effective and energetically sustainable desalination process.

Solar thermal energy combined with humidification–dehumidification process for desalination brackish water: Technical review

Water scarcity has become a chronic problem aggravated by climate change. One third of the world's population already lives in areas suffering moderate to high water stress; some 1.5 billion people lack ready access to drinking water. Desalination is in the course of becoming a major source of fresh water by tapping into the vast reserves of seawater and brackish water. Large scale desalination plants use either thermal or membrane processes which consume a great deal of energy. Economic implications of large energy requirements coupled with environmental concerns about carbon emissions spurred a growing interest in developing desalination processes that use renewable energy sources. Among these processes the humidification dehumidification (HD) of air, using solar energy, is a simple technology particularly suited for regions in developing countries where there is very low infrastructure and unskilled manpower.In this paper we review various technologies under investigation to desalinate saline water through HD of air and using solar thermal energy. A particular emphasis will be put on the various types of solar water heaters as well as the various designs of solar air heaters.

Small/medium nuclear reactors for potential desalination applications : Mini review

Small/medium nuclear reactors (SMRs) are a promising alternative for powering large scale desalination plants. The modern generations of these systems manifest cost effectiveness and built-in safety features. The compatibility with geological and topological challenges is an added advantage. Moreover, funding opportunities and packages could be easily arranged for small/medium nuclear reactors (SMR). This mini review article provides the latest technical features of SMR nuclear plants with emphasis on pressurized light water reactors (PWR), boiling water reactors (BWR), heavy water reactors (HWR), gas cooled reactors (GCR), and liquid metal fast breeder reactors (LMFBR). Preliminary cost indicators for typical units were investigated as a part of joint effort to develop a cost database for these types of reactors. Security and safety features of small/medium reactors are identified and reviewed. This paper identifies and briefly discusses the various types of small/medium nuclear reactors to provide a preliminary evaluation and consideration of using this type of reactor in potential seawater desalination applications.

Salt recovery from brine generated by large-scale seawater desalination plants

Water shortages in the Middle East and North Africa (MENA) region countries mandate the installation of large-scale desalination plants. Concentrate management requires properly operated cost-effective technologies to reduce the environmental impacts arising from brine discharge. Significant improvement in economics may be obtained by the recovery of chemicals from brines. This study addresses the management of modular brine streams generated from large-scale reverse osmosis desalination plants with microfiltration and nanofiltration (NF) as pretreatment stages. Appropriate salt recovery schemes have been identified and analyzed from the performance and environmental points of view. The economics of salt recovery schemes from NF and reverse osmosis (RO) brine based on evaporation ponds, brine evaporator and membrane crystallizer (MCr) are analyzed and compared. Phased application of the salt recovery program is considered. The results indicate that using NF as pretreatment and adopting salt recovery schemes provide higher water recovery in addition to producing valuable products. The adoption of MCr has high prospects for application in salt recovery from desalination brine. Increasing the capacities of salt recovery systems offers both technical and economic merits.