Seawater Reverse Osmosis Unit Research Articles

Optimal Sizing and Management of Hybrid Wind Turbine-Diesel-Battery System for Reverse Osmosis Seawater Desalination in NEOM City

Optimal sizing and management of hybrid wind turbine-diesel-battery system for reverse osmosis seawater desalination in NEOM city is the objective of the paper. Therefore, the paper explored the different factors to optimize and introduce a technoeconomic evaluation and energy management of a stand-alone wind turbine (WT) system, diesel generator (DG), and battery storage (BS). The suggested WT/DG/BS system is implemented to feed seawater reverse osmosis (SWRO) unit in NEOM. The necessitated desalinated water per day is 100 m3. To determine the optimal size of WT/DG/BS corresponding to the minimum cost of energy (COE) and net present cost, two different ratings of the SWRO units (SWRO-100 and SWRO-150), three control dispatch strategies (load following, cycle charging, and combined dispatch), and five types of batteries are considered. HOMER software is performed to simulate and optimize the WT/DG/BS. The optimization results indicated that the best battery storage is the Trojan SAGM battery. In this case, the COE ranged between $0.337/kWh and $0.564/kWh. The lowest COE of $0.377/kWh is obtained when using a combined control strategy and SWRO-100 unit, whereas the worst COE of $0.564/kWh is obtained when using load following control strategy and SWRO-150 unit. The best option of the WT/DG/BS system to supply the SWRO unit is option number 26. This system includes one wind turbine of 90 kW, DG of 25 kW, 47 Trojan SAGM batteries, a 23.8 kW converter, a SWRO-100 unit, and a combined control strategy. The net present cost and the initial cost are $950,725 and $221,495, respectively. The annual operating cost and annual consumed fuel are $56,409 and 36,396 L, respectively. Compared with using only a 25 kW diesel generator, the COE reduced from $0.373/kWh (using only DG/BS) to $0.337/kWh (using the best option) by around 9.65%. Under this condition, the values for the internal rate of return, return on investment, and simple payback are 11%, 7.8%, and 8.3 years, respectively.

Performance Analysis of Reverse Osmosis Desalination Plant, Study Case of BBRI Plant

Desalination using seawater resources has been a cornerstone in meeting both human and industrial water demands for several decades. Some well-known methods are thermal desalination and membrane desalination. Among these, membrane desalination stands out, employing reverse osmosis (RO) technology, wherein seawater is pressurized and forced through a semi-permeable membrane to produce purified water. Black Bear Resources Indonesia (BBRI), which operates in the chemical industry relies on RO technology to cater its desalination requirements within the manufacturing facility. Notably, BBRI's desalination plant is equipped with both Seawater Reverse Osmosis (SWRO) and Brackish Water Reverse Osmosis (BWRO) modules. In the SWRO unit, the Hydranautic SWC-6 Max membrane is employed, while the BWRO unit features the Hydranautic ESPA-2 LD membrane. Both modules adopt the spiral wound configuration utilizing polyamide composite material. To determine the reliability of factory operations and dependability, a comprehensive performance analysis of the SWRO and BWRO units is imperative. This analysis encompasses critical parameters such as Recovery Rate, Membrane Flux, Percent Rejection, Concentration Rejection, and Specific Energy Consumption (SEC). Notably, performance degradation in both SWRO and BWRO systems primarily stems from membrane fouling, scaling phenomena, and the natural aging of the membranes.

Using Seawater Reverse Osmosis (SWRO) Technology in Seawater Desalination Processes

Water is one of the basic needs for human life, including for people living on the coast. It is difficult to get clean water for consumption because most coastal areas are affected by sea conditions that have high salinity. In order to be consumed, the saline water must be desalinated. Desalination is a process to convert saline water into fresh water. One such desalination technology is using reverse osmosis (RO). The purpose of this study was to determine the process of desalination of seawater into freshwater using the seawater reverse osmosis (SWRO) method. The method used in this research is observation, which is to see directly the stages of the desalination process of seawater into fresh water. The data was obtained in the form of primary data from observations and secondary data from the literature to support primary data. Analysis of the data used in the form of descriptive analysis by describing each stage carried out in the SWRO process. The results showed that the seawater desalination process using SWRO technology had 14 stages. These stages include; intake, raw water pump, raw water reservoir, UF feed pump, Automatic screen, ultrafiltration, UF water reservoir, RO feed pump, HPP & booster, RO membrane, RO water reservoir, permeate pump, chlorine analyzer, product water. In developed and developing countries, SWRO units have been widely used, because by processing seawater into freshwater, there are many benefits for the life cycle and it is environmentally friendly. It also maintains underground fresh water so that it can provide plant life, and trees that provide us with clean oxygen for our lives.

Development of a computational tool for the design of seawater reverse osmosis desalination systems powered by photovoltaics for crop irrigation

Access to fresh water is a major human right as mankind existence depends on it. The balance between fresh water supply and actual water demand for agricultural purposes (irrigation) relies on the availability of fresh water in the underground aquifers or surface water resources. Water resources are under great pressure due to the high demand for irrigation to sustain crop productivity and cover domestic use as a result of demographic growth. Desalination of sea or brackish water is one of the solutions to provide water for irrigation in remote areas of limited freshwater reserves. In such areas, if desalination is powered by renewable energy sources, then it can become a lot more sustainable. This paper presents the development of an innovative computational tool for the optimal (economically and technically) design of seawater reverse osmosis desalination systems for sustainable water production for crop irrigation. In order to further reduce the cost of water produced, an energy management and control system was also designed and included in the computational tool to ensure the optimal operation of the desalination plant. This system allows the seawater reverse osmosis unit to operate at variable load and determines its optimal operation point using computational intelligence techniques based on fuzzy cognitive maps. According to the results, the implementation of the computational tool for the design of PV-SWRO system presents the lowest cost as compared to the system designed with the conventional methodology.

Alternative reverse osmosis to purify lactic acid from a fermentation broth

Brackish water reverse osmosis (BWRO) and seawater reverse osmosis (SWRO) membranes were used in a two-stage reverse osmosis (RO) unit to recover, pre-purify, and pre-concentrate lactic acid. Calcium lactate, sodium lactate, and ammonium lactate were used as model feed solutions. The operating pressure showed a pronounced effect on lactate passage through the first BWRO unit, and the Donnan exclusion effect and hydrogen bonding were responsible for cation rejection. Calcium ions were rejected at the BWRO unit because of low diffusion rate and charge interaction at the surface. However, monovalent ions formed hydrogen bonds with the carbonyl group of the membrane that allowed passage across the membrane. The second SWRO unit was for pre-concentrating lactic acid. A high lactate purity of 99.2% with a total recovery of 50.5% was acquired from calcium lactate feed solution. Lower purity with higher lactate recovery was obtained when the feed solution was sodium lactate and ammonium lactate. When the actual fermentation broth was used in the two-stage RO unit, a slightly lower recovery and purity of lactic acid were obtained. It was claimed that the total ions present in the fermentation broth were responsible for the low efficiency of the two-stage RO unit.

Synthesis of integrated membrane desalination and salt production networks

The development of desalination processes that are coupled with simultaneous salt production opportunities are increasingly receiving attention by the scientific community. This work is the first to propose a superstructure-based optimization approach that enables a systematic identification of high performance designs for such systems. The approach considers hybrid seawater reverse osmosis (SWRO) and nanofiltration (NF) membrane desalination together with salt production processes (SPPs). The proposed mathematical formulation has been developed based on a membrane superstructure, which mainly consists of SWRO, NF, and SPP as its primary synthesis units. The various connectivity options between synthesis units has also been explored in this work. For instance, SWRO and NF membranes follow slightly different connectivity patterns due to NF membrane's lower rejections for monovalent ions. The objective function identifies the minimum cost network embedded in the superstructure. The proposed method is illustrated with an example involving SWRO and NF membrane units as well as two different SPP options. The example highlights potential savings in water production cost as a consequence of salt value extraction. It further illustrates the benefits of integrated design of membrane desalination systems coupled with salt production processes over sequential designs of desalination processes followed by end-of-pipe salt production.

Performance investigation of a power, heating and seawater desalination poly-generation scheme in an off-shore oil field

Hydrocarbon production fields are energy-intensive, with significant demands for on-site power, process heat and fresh water, particularly in arid climates. A poly-generation scheme based on the conversion of gas turbine exhaust thermal power into mechanical work to drive a seawater reverse osmosis unit and generate process heat in an off-shore oil field in the Arabian Gulf is evaluated thermodynamically and economically. The prime mover exhaust thermal power is recovered using a bottoming organic Rankine cycle (ORC), with four working fluids used in commercial ORC systems evaluated. The performance of the poly-generation system is assessed both on a yearly and a seasonal basis. The octamethyltrisiloxane (MDM) cycle yields 6 MW of net power output at ideal and overall exhaust gas heat recovery efficiencies of 14% and 10%, respectively, 37 MW of process heat, and 1380 m3/hour of permeate. The reverse osmosis unit operates at a specific energy consumption and exergy efficiency of 4.1 kWh/m3 and 29%, respectively. The exergetic efficiency of the poly-generation system is estimated at 32%, thereby enhancing the efficiency of the original gas turbine power generation system by 6%. The system becomes profitable after approximately three years for subsidized local water and natural gas prices.

Reverse Osmosis–Pressure Retarded Osmosis hybrid system: Modelling, simulation and optimization

Theoretical analysis of energy harvesting from concentrated brine of Sea Water Reverse Osmosis (SWRO) system using Pressure Retarded Osmosis (PRO) is presented in this research. The mathematical model of SWRO–PRO hybrid system components such as SWRO unit, Energy Recovery Device (ERD), PRO unit and other auxiliary units were discussed. The mathematical equations were solved adapting an object oriented “Modelica language” framework in Dymola software tool. The complex flowsheet models for six different SWRO–PRO hybrid configurations were created. The performance of the SWRO–PRO hybrid system configurations was studied. The process and design parameters were optimized to reduce the Net Specific Energy Consumption (NSEC) of the system. The optimization studies were performed using SQP technique that is available in optimization library of Dymola. The possibility of using sea water (32,000g/m3) and urban waste water (100–10,000g/m3) as feed solution to the PRO for all the hybrid configurations were studied. Their performances were compared through simulation and optimization studies. Among the six potentially viable SWRO–PRO configurations, the one which does the direct mixing of diluted PRO draw outlet with feed water of SWRO aided to bring down the NSEC by 49% in comparison with standard SWRO desalination system. This system does not require additional ERD units and turbine at optimized process conditions, which are more expensive.

Experimental comparison of the performance of two reverse osmosis desalination units equipped with different energy recovery devices

Sea water reverse osmosis (SWRO) desalination constitutes a successful technology for covering local fresh water supply shortage in many areas of the world and especially in isolated areas such as islands and coastal regions. SWRO units can be combined with renewable energy (RE) technologies such as photovoltaic and wind generators. Small-scale SWRO units combined with energy recovery devices can decrease drastically the energy consumption of the SWRO units. Furthermore, it is proven that the operation of a desalination unit in part-load conditions can result in lower specific energy consumption compared to continuous full-load operation. This paper presents an experimental comparison between two small-scale SWRO units equipped with different energy recovery devices in order to lower the specific energy consumption. The first SWRO unit consists of a hydraulic energy recovery device of the Clark pump type which plays also the role of the high-pressure pump in a conventional reverse osmosis unit. The second SWRO unit is equipped with two types of Danfoss pumps (a rotary piston pump and a motor pump), based on the axial piston principle. The main objective of the comparison is the identification of the energy recovery device with the lowest specific energy consumption of the SWRO unit. Both units are installed at the Laboratory of Agricultural Engineering of Agricultural University of Athens and they are tested under full- and part-load conditions. The experimental operation of the SWRO units in part-load conditions is achieved by varying the speed of the motor pump assembly, the pressure and the flow rate of the feed water. During the evaluation of the measurements results, an optimum operating window was drawn regarding the operation of the SWRO desalination units in part- and full-load conditions. More specifically, the minimum measured specific energy consumption of the Clark SWRO unit was found to be 5.7 kWh/m3 at a pressure of 44 bar while the Danfoss SWRO unit showed a minimum specific energy consumption of 4 kWh/m3 at a pressure of 59 bar. With these results, a SWRO unit equipped with an energy recovery device operating under full- and part-load conditions is suitable for future direct connection with RE systems such as photovoltaic and wind turbines.

Corrosion of stainless steel components in seawater reverse osmosis desalination plants—investigations on adapted internal cathodic protection

Stainless steel is widely used in seawater reverse osmosis units (SWRO) for both good mechanical and corrosion resistance properties. However, many corrosion failures of stainless steel in SWRO desalination units have been reported. These failures may often be attributed to un-adapted stainless steel grade selection and/or to the particular aggressive seawater conditions in “warm” regions (high ambient temperature, severe biofouling, etc.). Cathodic protection (CP) is a well-known efficient system to prevent corrosion of metallic materials in seawater. It is successfully used in the oil and gas industry to protect carbon steel structures exposed in open-sea. However, the specific service conditions of SWRO units may seriously affect the efficiency of such anti-corrosion system (high flow rates, large stainless steel surfaces affected by biofouling, confinement limiting protective cathodic current flow, etc.). Hence, CP in SWRO units should be considered with special care and modeling appears as useful tool to assess an appropriate CP design. However, there is a clear lack of CP data that could be transposed to SWRO service conditions (i.e. stainless steel, effect of biofouling, high flow rate, etc.). From this background a Join Industry Program was initiated including laboratory exposures, field measurements in a full scale SWRO desalination plant, and modeling work using PROCOR software. The present paper reviews the main parameters affecting corrosion of stainless steel alloys in seawater reverse osmosis units. CP on specific stainless steel devices was investigated in order to assess its actual efficiency for SWRO units. Severe environmental conditions were intentionally used to promote corrosion on the tested stainless steel products in order to evaluate the efficiency of CP. The study includes a modeling work aiming at predicting and designing adapted CP protection to modeled stainless steel units. An excellent correlation between modeling work and field measurements was found.

Experimental investigation of the performance of a reverse osmosis desalination unit under full- and part-load operation

Sea water reverse osmosis (SWRO) desalination constitutes a successful technology for covering the potable water needs of islands and coastal regions. SWRO units can be combined with renewable energy technologies such as photovoltaic and wind generators. Conventional small scale SWRO units are not often combined with energy recovery devices; however, these devices can decrease drastically the energy consumption of the SWRO units. Furthermore, in the literature there are references which prove that the operation of a desalination unit in part-load conditions can result in lower specific energy consumption compared to full-load operation. This paper presents the simulation and the experimental investigation under full- and part-load conditions of an existing SWRO desalination unit (50 mS/cm feed water) in order for the desalination unit to be optimally utilized in a polygeneration microgrid topology which uses advanced energy management algorithms. The experimental operation of the SWRO Unit in part-load conditions is achieved by varying the speed of the motor—pump assembly, the pressure and the flow rate of the feed water. During the evaluation of the measurements result, an optimum operating window in the range of 40–57 bar was drawn regarding the operation of the SWRO desalination unit in part- and full-load conditions. More specifically, in this pressure range the average value of fresh water production was 60 L/h with an acceptable fresh water electrical conductivity of 550 μS/cm, and with a specific energy consumption range from 6.1 to 7.7 kWh/m3. With these results the operational parameters of the polygeneration microgrid energy management system can be optimized.

A comparative study for boron removal from seawater by two types of polyamide thin film composite SWRO membranes

In this paper, field performance of a small-scale seawater reverse osmosis unit installed in Urla Bay-Izmir, Turkey was analyzed and presented. The design of SWRO system in Urla consists of two types of FilmTec polyamide thin film composite spiral wound seawater reverse osmosis membranes (high rejection FILMTEC XUS SW30XHR-2540 RO membrane and FILMTEC SW30-2540 RO membrane) which could be operated in parallel. To make a comparative study between two types of membranes regarding their desalination performances and boron rejections, each membrane was operated individually for each set of experiments. This comparison was made via investigation of the effects of feed seawater temperature (10–16 °C), operating pressure (55, 60 and 62 bar), and pH adjustment on the feed side (pH 7.0–7.5).

Prediction of performance of sea water reverse osmosis units

This paper presents a methodology for the prediction of the performance of sea water reverse osmosis units acquired by salient mathematical correlations which involve the important aspects of membrane input and output variables. Feed water conditions pertinent to flow rate, TDS (total dissolved solids), pressure, pH and temperature are correlated with recovery ratio, permeate TDS and power consumption via regression analysis. Satisfactory results are obtained by comparing the resulting correlations against the software ROSA predictions. The mathematical correlations and regression assessment led to the derivation of simple polynomial expressions which were used for sensitivity analysis and may be useful for the design, monitoring and control of this important desalination process.

Desalination in the Developing World: Tsunami Reconstruction in Maldives

AbstractOn Dec. 26, 2004, the second-largest recorded earthquake caused a series of tsunamis in the Indian Ocean, the effects of which were devastating to the poor, low-lying island nation of Maldives. In response, USAID provided 1.8 million in new programming to benefit two of the largest islands, Hinnavaru and Naifaru. Program objectives included improving health care services by providing a safe, reliable potable water supply utilizing desalination and building local capacity. The project 's technical aspects involved design, installation, and commissioning of two 8,000-gpd seawater desalination units, as well as an open seawater intake system, multimedia filter pretreatment, seawater reverse osmosis units, stabilization and disinfection, brine management, distribution, and emergency energy generation. Project sustainability involved government and local stakeholders, including USAID, three Maldivian government organizations, island chiefs, and local water committees. The lessons learned are particular...

Ultrafiltration pretreatment to reverse osmosis for seawater desalination — three years field experience in the Wangtan Datang power plant

Systems composed of ultrafiltration (UF) pretreatment for seawater reverse osmosis (SWRO) desalination are often termed “integrated membrane system” or “dual membrane system”. These systems promise to offer reliable handling of very difficult waters, also in regions which have traditionally experienced feed water and pretreatment problems such as Middle East and United States. Nevertheless, data sets presenting long-term integrated operation from a UF and SWRO point of view at a larger scale level, and hence validating the potential cost benefit of UF pretreatment, are very scarce. The dual membrane seawater desalination system at the Wang Tan Power Plant has been operating for three years and is an ideal case to present learnings. Despite some gaps in the data set, some operational problems, and an unconventional low flux and low chemicals operation approach, the authors believe that transparent sharing of this data set can significantly contribute to a better industry understanding of integrated operation. The data shows that UF system operation is possible using a low flux (25 L/m2;/h), low chemical approach. This approach totally eliminates the need for coagulation or chemical enhanced backwash, and uses only yearly clean in place operations. This requires higher upfront capital investment, but results in lower chemicals cost, lower sludge and chemical brine disposal, better ease of operation and higher safety level. This approach has allowed reliable water production in the DOW™ UF and FILMTEC™ SWRO unit for 3 years and should be interesting for very environmentally aware regions with difficult waters, such as Australia or United States. Based on limited data, turbidity removal rate was 98–99.5% and outlet SDI typically <2.5. On a water with very high temperature fluctuation, this enabled SWRO operation with slow pressure drop increase and normalized flux loss, hence resulting in low cleaning frequency of around yearly clean in place operation, and low replacement rate of 1%/a. The data also shows that care should be taken that chlorine employed in ultrafiltration backwash operations does not attack SWRO membranes — improved modes eliminating these problems are available and discussed within the paper. Ultimately, a one-year pilot trial in the SWRO plant shows that the combination of ultrafiltration and internally staged design, employing high productivity elements such as FILMTECTM SW30ULE-400i is synergistic and can enable unprecedented SWRO vessel productivity of 5 m2;/h and flux rate in the range of 25 L/m2;/h, while achieving excellent water quality in the range of below 500 µS/cm.

Performance analysis of a trihybrid NF/RO/MSF desalination plant

The Saline Water Desalination Research Institute (SWDRI) of the Saline Water Conversion Corporation (SWCC), Saudi Arabia has been actively involved in developing the application of nanofiltration (NF) pretreatment to both seawater reverse osmosis (SWRO) and multistage flash (MSF) desalination processes. Full integration of NF, SWRO and MSF processes would result in enhancing the reliability, flexibility, plant productivity and ultimately reduce water production cost. Extensive experimental studies on a pilot-scale were conducted recently by SWDRI to establish the operational boundaries and constraints of the trihybrid NF/RO/MSF desalination system. The system was configured in such a way that the NF unit received seawater feed from the heat rejection of the MSF pilot plant and was able to operate at a fairly constant temperature of about 33°C which produced NF permeate (NFP) at a recovery ratio of about 64%. The SWRO unit which received the NFP as a feed yielded a permeate recovery of about 47%. Average chemical analysis of the RO reject (ROR) revealed that the sulphate and calcium concentrations were only 124 and 281 ppm, respectively, and was subsequently used as a make-up to the MSF pilot plant. The very low concentration of the sulphate and calcium ions in the brine recycle which were below the saturation limits enabled to operate the MSF unit safely up to a top brine temperature of 130°C (unit temperature design limit) and water recovery ratio of about 69%. In this paper, the operational performance of the trihybrid NF/RO/MSF desalination pilot plant will be presented. The established optimum operating conditions can be used as a guide to assess the techno-economic viability of the trihybrid desalination scheme.

Myth and reality of the hybrid desalination process

The paper discusses some misconceptions that have contributed to the continued use of thermal desalination processes and promotion of the hybrid desalination process for new plants being built or considered at Middle East locations. The misconceptions are examined both on the basis of fundamental thermodynamic principles and in terms of practical engineering parameters. The analysis shows that there is no economic or performance advantage in the installation of greenfield hybrid power/thermal desalination/ seawater reverse osmosis (SWRO) plants in preference to power/SWRO plants, because the latter would produce water more cheaply under all conditions and at all fuel costs, and would provide more operational flexibility than the former. The paper identifies situations where the hybrid desalination process can be fully justified: in existing power/desalination plants, where aging boilers and multistage flash (MSF) units need to be repaired or replaced, through retrofitting and repowering. In such situations, abandonment of the MSF process would result in a reduction in the power output of the plant. The paper refers to previous work which showed that the repowering of a typical existing power/desalination station with refurbishment/replacement of the MSF units, together with the addition of SWRO units, would result in a several-fold increase in the water and power output and a dramatic improvement in the fuel efficiency, without any additions to the existing seawater intake system. The paper emphasizes the importance of test stations/demonstration plants at existing power/desalination stations in the Middle East in order to obtain data and make improvements in the technology of higher temperature SWRO, with the feed obtained from the cooling water returning from the power plant condenser and the thermal desalination plant. The paper shows that the potential benefits would easily justify the investment in research and development required to validate this concept.

Experiences in the construction and operation of a nuclear desalination demonstration plant: Part II

A hybrid desalination plant consisting of 1800 m³/day Seawater Reverse Osmosis (SWRO) and 4500 m³/day Multi-stage Flash (MSF) distillation units, is being set up at Kalpakkam, near the Madras Atomic Power Station (MAPS). The construction of both these units has resulted in many challenges, imposing severe constraints as they are being retrofitted to the existing power plant. The steam supply system and seawater intake system required unique approaches, both in erection and commissioning. The MSF evaporator modules require the precise fabrication and assembly of thousands of tonnes of carbon steel, stainless steel and cupronickel. This being the first desalination plant of its kind in the country, we had to overcome numerous obstacles and face surprises and peculiar problems. In spite of this, the SWRO unit has been in operation since October 2002 and, for the MSF unit, the brine heater, brine circulation pumps, holdup tank, and isolation heat exchangers have been completed and construction of the evaporator module is in full swing and is likely to go on stream in near future. This paper attempts to describe the problems encountered during the erection, commissioning and operation of the Nuclear Desalination Demonstration Plant (NDDP) at Kalpakkam.

Preliminary design of a solar thermal-powered seawater reverse osmosis system

This paper presents a preliminary design for a solar thermal-powered reverse osmosis desalination system. The high pressure pump in the seawater reverse osmosis unit requires a 95-kW input, while the reject energy is recovered by way of pressure exchangers. The unit's specific energy consumption is 6.48 MJ/m 3 (1.8 kWh/m 3) for a recovery rate close to 50% and a feed pressure of 5.53 MPa. The unit was coupled to a solar power cycle based on a Rankine cycle with toluene, hexamethyldisiloxane (MM) and octamethylcyclotetrasiloxane (D4) as working fluids and two different models of parabolic trough collectors. In addition, configurations using both direct vapor generation as well as a heat transfer fluid are proposed. The coupling was done assuming all the mechanical energy produced by the cycle was consumed by the high pressure pump in the reverse osmosis unit. A subsequent assumption was that all the cycle's rejected thermal energy went to preheat the seawater feed flow. This latter aspect does not result in a significant increase in the desalinated water output. The results obtained indicate that with the system proposed it is possible to produce, for a solar direct irradiance of 850 W/m 2, 0.11 m 3/h with toluene as the working fluid in the cycle and 0.088–0.094 m 3/h with D4 or MM of desalinated water per square meter of LS3s parabolic trough collector aperture area. Likewise, for the IND300 collector, it is possible to obtain 0.078–0.085 m 3/h with toluene and 0.07–0.077 m 3/h with D4 or MM.

Simulation and Optimization of Medium-Sized Seawater Reverse Osmosis Processes with Spiral-Wound Modules

A numerical model is presented for a two-stage seawater reverse osmosis (SWRO) desalination unit with spiral-wound modules. The model, which is based on the mass and momentum transport equations, takes into consideration the longitudinal variation of the velocity, the pressure, and the salt concentration in the membrane modules. This model was calibrated with the field data of a 600 m3/day SWRO unit of the desalination plant of Porto Santo Island (Portugal) and was used to optimize the module configuration and the operating conditions of a medium-sized SWRO with spiral-wound modules. For a typical reverse osmosis (RO) plant with a capacity of 1000 m3/day, with a single stage and four membrane modules (FilmTec SW30HR-380) per pressure vessel, operating at a feed pressure of 6.0 MPa and with an inlet feed velocity of 0.12 m/s, the water recovery rate is 33%, the energy consumption is 4.28 kWh/m3, and the specific water cost is 81.4 eurocent/m3. The water cost can be reduced to 66.7 eurocent/m3, for a two-stage SWRO unit operating at a 56.7% water recovery rate, with seven membrane modules per pressure vessel, operating at transmembrane pressures of 7.2 and 8.0 MPa and inlet feed velocities of 0.23 and 0.20 m/s, in the first and second stages, respectively.