Evaluation for the optimization of two conceptual 200,000 m3/day capacity RO desalination plant with different intake seawater of Oman Sea and Caspian Sea

Integrated Pumped Hydro Reverse Osmosis System optimization featuring surrogate model development in Reverse Osmosis modeling

With a reverse osmosis (RO) desalination plant designed to satisfy only the contracted-for water supply, the water company would be missing out on potential benefits that could have been obtained selling water in periods of high demand. On the other hand, sizing the RO desalination plant to produce water to satisfy peak demand means incurring additional costs as well as having the plant partially idle during periods of average or low demand. A model was developed using Excel macros to perform dynamic programming to optimize the capacity expansion of an RO desalination plant. The objective function is to maximize the present value of the total net benefits over the lifetime of the RO desalination plant. The model can be used to test different scenarios to capture time-variant tourism demand and price uncertainties on investment decisions. This study focuses on tourism dominated arid coastal regions, using Sharm El Sheikh (Sharm) in South Sinai, Egypt, as an example.19 RO plants in Sharm were surveyed and data were collected including unit production costs, O&M costs, energy consumption rates, contracted-for water supply, and utilization. Unit production cost of an RO desalination plant varies according to the degree of operation of the plant. This fact has to be taken into consideration when calculating the costs of RO desalination and when deciding on the plant capacity in order to maximize the total net benefit. Using the collected data, cost functions were developed for O&M costs as a function of utilization and plant capacity. The cost model calculated similar values to the actual total net benefit for one of the surveyed RO plant taken as an example. Using the optimization model, the maximum total net benefit is obtained with a smaller installed capacity than the actual case. A modified pricing structure is suggested in the paper that ties the water selling price to consumption in an effort to reduce demand in excess of contracted-for water supply aiding the water company to fulfill its contractual commitments to all users. However, price elasticity has to be taken into consideration to determine the impact of price change on water demand.

A theoretical analysis on upgrading desalination plants with low-salt-rejection reverse osmosis

Sea and ocean Reverse Osmosis (RO) desalination plants are often designed to remove more than 90% of dissolved ingredients (organic and inorganic) from feed water, thus creating a permeate water that is potable. Typically 40–60% of the feed water is recovered as permeate water. The water not recovered as permeate becomes concentrated into a stream of RO concentrate (brine) because the salts rejected by RO remain in the unrecovered water. The RO concentrate is usually about 1.67 to 2.5 times the salt concentration of the source water, but can be as high as four times. RO concentrate discharged into a source water body is a major environmental consideration during the planning and design of bay or ocean desalination plants. Co-location of desalination plants with wastewater treatment plants or power plants allows using a shared outfall to dilute the high salt concentration of RO concentrate. Diluting the RO concentrate in a shared effluent outfall mitigates the issue of high salinity around the outfall. This paper compares side by side two main classes of water bodies that receive concentrated brine discharge from Reverse Osmosis (RO) Desalination Plants: oceans (or open seas) and estuarine bays (under the influence of fresh water). These two classes of water bodies have inherent properties which drive not only the operation of RO plants, but also the physical and chemical reactions of outfall discharge. Major differences between oceans and estuarine bays are evident when comparing salinity levels, variability of salinity, and variability of the overall water quality. Furthermore, there are differences in terms of flora and fauna. Using a nuanced approach of comparing and contrasting oceans and estuarine bays as receiving waters for desalination plant concentrate, this paper brings to light the natural processes occurring offshore of potential desalination plant sites, and distinguishes what natural processes may be affected by brine entering the ecosystem.

the adaption of renewable energy (RE) in electric systems (ESs) involves many technical challenges when its share exceeds certain levels. Various strategies are used to manage these challenges. The reverse osmosis (RO) desalination plants can play a significant role in RE integration because of their high energy consumption and flexibility of operation. This paper investigates how RO desalination plants can help in integrating RE resources in ESs. First, the impact of different levels of RE penetration on IEEE 30-bus system was studied in terms of voltage profile. Then, the adaption of an RO plant in the system as a flexible load was introduced to reduce the effects of RE penetration. The consumption of RO plant was decreased during the absence of RE and increased at the midday hours to absorb the surplus power generated by RE. This prevented the ES voltage profile to fall below the permissible limits. The results showed that, the coordination between RO plants and ESs operation had a significant positive role.

Capital cost estimation of RO plants: GCC countries versus southern Europe

Modeling, control, and dynamic performance analysis of a reverse osmosis desalination plant integrated within hybrid energy systems

The “Salty solutions” Quick Study by Greg Thiel (Physics Today, June 2015, page 66) was encouraging for the progress it described in desalinating seawater by reverse osmosis (RO). There is, however, some confusion with the thermodynamics. Thiel does recognize that not all kilowatt-hours are created equal, and the electrical energy (work) to drive the RO pump is the highest-grade energy, as compared with the low-grade heat that drives an evaporative process. He lists energies for RO in kWhe (kilowatt-hours of electrical work) per cubic meter of fresh water and compares that with the kWhe of heat required for thermal evaporation processes, but there is no specified conversion or equivalence factor. Is it based on the Carnot equation (for an assumed temperature difference) or on some practical thermodynamic cycle such as Rankine? A conversion factor is fundamental if the reader is to make any useful comparison.Permit me also to raise a practical point. We generally use an engine, a water or wind turbine, or a photovoltaic array to generate electricity, whereas heat is readily available from solar thermal collectors or geothermal sources. Some may even be virtually free, such as waste heat from another process or industry. The economic choice, therefore, between RO and thermal evaporation may not always favor RO despite its numerically lower kWhe input number. The decision would properly depend on the forms of energy available to a particular desalination plant.In no case other than a survival emergency would it make sense for either process to run on fossil-fuel combustion, since the resulting carbon dioxide emissions would only exacerbate the climate change that is often at the root of the drought that the desalination plant is supposed to alleviate.© 2015 American Institute of Physics.

Desalination is probably the only means for fresh water supply to countries in decertified climate. The majority of GCC counties rely on desalinated water for fresh water supply to major cities. Over 70% of the desalinated water in the GCC comes from thermal desalination plants including Multi Stage Flash (MSF) and Multi Effect Distillation (MED). The new trend in the desalination plant in the GCC is 30% Reverse Osmosis (RO) and 70% thermal. However, these percentages vary from one to another country depending on feed water quality and expertise. For example, Oman Sea has lower salinity than the Gulf water and hence Oman uses more RO for desalination than MED and MSF. This decision is also driven by economy as RO process less energy intensive and hence the produced water is less expensive as compared to thermal plants. On the contrary, Qatar and Kuwait use more MSF followed by MED due to the high salinity and low quality feed water. This is also because trials of RO in both Qatar and Kuwait were not successful because of the problems of membrane fouling and restrict pre-treatment requirements due to the quality of the water intake.The advantages of RO over thermal technologies are well known in terms of lower energy consumption and the cost of produced water; but are not yet taken advantage of in the GCC zone. One of the reasons is blamed on high feed water salinity and bad water quality; other reasons such as lack of experience, red tides and reliability are contributed to the dominance of thermal plants. However, field experience showed that good pretreatment and optimized RO design may overcome the problems of high feed salinity and bad water quality. Several RO plants, such as Fujairah in UAE, are good examples of a working RO technology in the harsh water environment. Good RO design includes design and optimization of both pretreatment and post-treatment. Field experience showed that most of RO plants failure was due to inefficient pretreatment which resulted in providing low quality water to the RO membrane that caused fouling. Fouling, including biological and scaling, can be handled once an efficient pretreatment process is available. Recent advances in pre-treatment techniques include the combination of Forward Osmosis (FO) with RO among other methods. Recent studies by the authors including commercial implantations have shown that the combination of FO with RO addresses the most technical challenge of RO process and that is fouling, which results in lower energy consumption and less chemical additives. Experience showed fouling in FO process in reversible, i.e. can be removed by backlashing while fouling in conventional RO process is irreversible.In this study, the feasibility of integrating FO with RO process for the desalting of the Gulf water in Qatar is presented. The results are expressed in terms of specific energy consumption, process recovery, produced water quality, chemical additives and overall process cost.The implementation of RO for desalination is not only reducing the cost of desalination but also the environmental impact. More R&D should be done to provide useful data about RO application and suitability for the Gulf water. The R&D should be focused on laboratory to market development of RO technology using rigorous lab scale and pilot plant testing program.

Today, reverse osmosis membranes are the leading technology for new desalination installations, however, a challenge facing widespread application of RO technology is membrane fouling. In the present study, we used an environmentally friendly green inhibitor as anti-scaling and anti-biofouling in reverse osmosis (RO) desalination plants. The influence of Sargassum sp., Corallina mediterranea, and Avicennia marina on RO membrane mineral scaling was evaluated using gypsum as a model scalant. Antibacterial properties for three marine extracts from Sargassum sp., C. mediterranea, and Avicennia marina were investigated with Gram-positive bacteria (ArthrobactersulfureusYACS14, Staphylococcus aureus) and Gram-negative bacteria (VibrioanguillarumMVM425, Escherichia coli). The antimicrobial results were detected for the two selected extracts as the most potent extracts (ethyl acetate, methanol crude extracts of the Avicennia marina leaves). Data showed that ratios of 3 and 5% recorded the highest suppression percentages (100%) for all tested bacteria including bacterial community collected from Eastern Harbor. On the other side, data confirmed that the anti-scalant properties by 100 ppm of Avicennia marina leave extract giving 85% of scale inhibition. The effect of Avicennia marina leaves extract for calcium sulfate dihydrate (gypsum) scaling on selected reverse osmosis (RO) membrane surfaces was investigated. The effect of different concentrations of Avicennia marina leaves extract was observed in the extent of surface scale coverage and surface crystal size among the membrane studied.

The south Mediterranean area is suffering from lack of drinking water. However, brackish water is abundant in these regions. Desalination of such water can be a solution to provide the needs of the local populations (less than 10 m 3 /day). Different solutions for brackish water desalination have been developed and many prototypes have been built and tested. Bourouni et al. (1999) developed a water desalination plant based on Aero- Evapo-Condensation Process (AECP). A prototype was built and tested in the region of Kebili in the south of Tunisia. A geothermal brackish water source was used to feed the unit. Promising results were found, since the cost of water was reduced to 1.2 USD per cubic meter of fresh water (Bourouni et al, 1999). The present study shows that the geothermal source can be replaced by solar preheated water. The efficiency of the whole system can be improved by using air flat-plate solar collectors to preheat the air entering the evaporator of the AEC system. Warm air has a higher evaporative capacity than ambient air, and thus, the evaporation of brackish water will be faster and more efficient. In this paper we present a methodology to obtain the best configuration of coupling solar energy to the desalination unit and to optimize the surface collectors used to preheat water and air. TRNSYS simulations are held to predict the performances of the new design of the system. A life cycle cost analysis of the new system design is held to evaluate the cost of a cubic meter of fresh water produced by this innovative process. Different configurations of the plant are studied by detailed simulations. For a small unit producing 3 m 3 of fresh water per day, the cost obtained is as low as 1.58 USD per cubic meter of fresh water produced.

Water scarcity and the poor quality of water resources are leading to a wider diffusion of desalination plants using the Reverse Osmosis (RO) process. Unfortunately, the cost of a cubic meter of fresh water produced by an RO plants is still high and many efforts are in progress to increase the efficiency of the membranes used in osmotic plants and to limit the energy required by the process. A further reduction of the energy cost could be obtained by an optimal operation of the desalination plant so reducing the hourly energy cost, or by coupling the RO plant with an energy production plant based on direct osmosis (Pressure Retarded Osmosis PRO). The economic viability of the desalination process has been analyzed until now without accounting for the integration of the RO plant with the existing water network. This analysis is developed in the present paper with reference to a hypothetical change of water supply in a real network, where a desalination plant is used to satisfy the fresh water demand. Several scenarios will be analyzed to assess the minimum cost of fresh water production and water supply to the network, including the use of energy recovery systems, such as an integrated use of RO and PRO processes, or the regulation of pressure at the network intake by a micro hydro power plant.


 Seawater intake and its treatments are one of the main upstream processes of every seawater desalination plant (RO, ED, MSF, MED). However, the process has turned out to be of utmost importance for reverse osmosis (RO) desalination plant. It is to be sure that sufficient and steady flow and quality of water is available to the RO desalination plant. Prior to RO feed water, the seawater intake pre-treatment process has to be tailored and the quality of seawater intake to be treated either subsurface intake or open surface intakes, particularly when treating open surface intakes seawater (OSIS) with exceedingly unpredictable quality. According to the well-established membrane manufacturer and supplier, the RO membrane warranty and guarantee are depended on seawater intake quality and its pre-treatment. Thus, the current state-of-the-art RO membranes life and performance success for desalination processing depend upon OSIS pre-treatment processing techniques. This article is emphasizing an overview on recent OSIS and its pre-treatment techniques for RO desalination plant.

A feasibility study of a small-scale photovoltaic-powered reverse osmosis desalination plant for potable water and salt production in Madura Island: A techno-economic evaluation

Impact of solar energy cost on water production cost of seawater desalination plants in Egypt