Reverse Osmosis Desalination Plant Research Articles

Design and economic evaluation of solar-powered hybrid multi effect and reverse osmosis system for seawater desalination

Reducing the cost of fresh water has always been a major concern in the desalination industry. A solar powered hybrid multi-effect distillation and reverse osmosis desalination plant (MED + RO) has been designed and optimised from an economical point of view in a previous work by the same authors. In the present study, the possibility of coupling the desalination plant with a photovoltaic (PV) solar farm is investigated, with the aim of generating electricity at low cost and in a sustainable way. A detailed mathematical model for the PV system has been implemented from the literature. Interestingly, the model can predict the cost of the PV system in terms of capital cost and electricity cost per kWh considering the input data of solar irradiation, duration of daylight and technical specification of a real solar module. Consequently, the solar PV model has been combined with the desalination model, which enables to estimate the cost of fresh water per cubic meter. Data about four locations, namely Isola di Pantelleria (IT), Las Palmas (ES), Abu Dhabi (UAE), and Perth (AUS), have been used to economically test the feasibility of installing the proposed plant, and especially of the PV solar farm.

Flux Optimization in Reverse Osmosis via the Solution-Diffusion Model

This paper suggests a new method of predicting flux values at reverse osmosis (RO) desalination plants. The study is initiated by using the solution-diffusion model that is applied to the groundwater source at Abqaiq plant (500 RO plant) at Saudi Aramco, Dhahran, Saudi Arabia in order to calculate the osmotic pressure of the treated water for Shedgum/Abqaiq groundwater. For modelling purposes, the same technique is used to determine the osmotic pressure drops at the same plant configuration and operating conditions when using seawater sources such that of Arabian Gulf and the Red Sea waters. High rejection brackish water RO (BWRO) element Toray TM720D-400 with 8" is the RO membrane type that is used at Abqaiq plant. The calculated osmotic pressures of the three water sources, assuming that they are all treated at Abqaiq plant, are utilized to determine the appropriate flux values as well as membrane resistances of different BWRO Toray membranes. Values of numerous parameters such as water permeability constant, applied pressure, gas constant, water temperature, water molar volume and membrane thickness, water salinity/TDS are taken into account to develop our calculations through the solution-diffusion model. A comparison between low-pressure, standard and high-pressure BWRO Toray membranes performance have been established to select the ideal membrane type for the treatment of water from various sources at Abqaiq plant. The model results confirm an inverse relationship between the membrane thickness and the water flux rate. Also, a proportional linear relation between the overall water flux and the applied pressure across the membrane is identified. Higher flux rates and lower salinity indicate lower membrane resistance which yields to the higher water production. Modelled data predict that BWRO Toray TM720D-440 with 8" membrane is the optimal BWRO membrane choice for the three water sources at Abqaiq plant.

A modified controller design based on symbiotic organisms search optimization for desalination system

Abstract Fresh water demand is growing drastically in many parts of the world. Desalination of seawater, brackish water, and waste water is one solution to meet the demands of fresh water. Currently, reverse osmosis (RO) desalination process is one of the best methods for the desalination process. In this study, a modified controller design is proposed for RO desalination system based on symbiotic organisms search (SOS) algorithm. A multivariable model of RO desalination plant is considered for experimentation. The RO system considered here is first decoupled using a simplified decoupling process to obtain two non-interacting loops. Then, a proportional-integral-derivative controller with second order derivative (PID-DD) scheme based on SOS algorithm is proposed for each loop to find optimal control parameters of the RO system. To design the PID-DD controller for each loop, integral of squared error (ISE) is considered as fitness function. Four other state-of-the-art optimization algorithms, namely, teacher-learner-based-optimization (TLBO), differential evolution (DE), particle swarm optimization (PSO), and artificial bee colony (ABC), algorithms are also tested for the considered system. To show competitiveness of the proposed SOS-based PID-DD controller, a comparative study based on time domain analysis is performed. Results show the SOS-based PID-DD controller is superior to other PID-DD controllers.

Use of Nanoparticles for the Disinfection of Desalinated Water

When chemical disinfection is performed before or after desalination, a number of harmful compounds are formed. Thus, efforts have been directed toward developing alternative methods for water disinfection. In this study, seven nanoparticles (NPs) were evaluated for disinfecting water produced from reverse osmosis and multi-stage flash desalination plants. The tested NPs were silver, copper, silver-copper, zinc oxide, magnesium oxide, silicon dioxide, and carbon nanotubes. The antimicrobial activity of the NPs was investigated by batch studies in desalinated water samples spiked with E. coli, Enterobacter, Salmonella, and Enterococci. The Chick-Watson model was fitted to the inactivation data to evaluate the kinetic constant for each combination of NPs, water type, and indicator bacteria. The results indicated that silver and silver-copper NPs have the highest disinfection efficiency among the tested NPs. Among the bacteria, Enterobacter (strain TPC129) appears to be the most inactivated, while Enterococci (strain NCTC775) seems to be the least influenced by the NPs. Variations in the chemical characteristics of the tested water samples appeared to cause noticeable differences in the antibacterial efficacies of copper and magnesium oxide NPs, but not in those of the other NPs.

Biofouling in seawater reverse osmosis (SWRO): Impact of module geometry and mitigation with ultrafiltration

Since no pretreatment method is foolproof for the removal of foulants in reverse osmosis (RO) systems, the aim is to keep the production process efficiency as high as possible. In the vast majority of RO desalination plants, biofouling of membranes is considered as one of the most common operational problems. In this study, a full-scale seawater reverse osmosis (SWRO) desalination plant which was subject to severe biofouling was investigated. Autopsy showed higher biofilm concentrations near the inlet of the module likely due to the abundancy of nutrients. CFD simulation was also used to realize how the geometry of the module inlet could impact the flow within the membrane leaves and thus biofouling. A pilot-scale system including silicon carbide ultrafiltration (SiC-UF) membranes was established in order to filter biological matters. According to the results of this study, SiC-UF membranes appeared to be a reliable pretreatment method for removing almost 100% of all micro-organisms.

Green Inhibitor as Antibacteria and Antiscaling in Reverse Osmosis Desalination Plants

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.

Green Inhibitor as Antibacteria and Antiscaling in Reverse Osmosis Desalination Plants

Green Inhibitor as Antibacteria and Antiscaling in Reverse Osmosis Desalination Plants

Super-twisting sliding mode control and robust loop shaping design of RO desalination process powered by PV generator

Reverse osmosis (RO) desalination technique is the most widely used technology for supplying fresh water since it offers many advantages. Developing an accurate control strategy is one of the most challenging jobs in RO desalination plant especially under uncertainties and disturbances conditions to avoid all possible system failures and damages for safe operations. This paper presents an overall architecture of reverse osmosis desalination process supplied by a stand-alone photovoltaic (PV) system. A dynamic modeling of various components of this architecture is developed. A control strategy of the whole system is addressed with a controller for each part. Furthermore, special attention is given here to the robust control design of reverse osmosis (RO) membrane to address large set point changes and capability to reject external disturbances and to cope with parametric uncertainties as variations in feed water salinity. The control block is divided into two loops the first one using the loop shaping design method and the super-twisting sliding mode control is applied for the second loop. Simulation results investigating different scenarios show the efficiency of the proposed scheme.

Fuel cell as an effective energy storage in reverse osmosis desalination plant powered by photovoltaic system

Abstract A hybrid renewable energy systems (HRESs) comprises of photovoltaic (PV), and self-charging fuel cells (SCFC) is designed for securing electrical energy required to operate brackish water pumping (BWP) and reverse osmosis desalination (RO) plant of 150 m3 d-1 for irrigation purposes in remote areas. An optimal configuration of the proposed design is determined based on minimum cost of energy (COE) and the minimum total net present cost (NPC). Moreover, a comparison with a stand-alone diesel generation (DG) or grid extension is carried out against the optimal configuration of PV/SCFC HRES. The modeling, simulation, and techno-economic evaluation of the different proposed systems, including the PV/SCFC system are done using HOMER software. Results show that PV array (66 kW), FC (9 kW), converter (25 KW) –Electrolyzer (15 kW), Hydrogen cylinder (70 kg) are the viable economic option with a total NPC of $115,649 and $0.062 unit cost of electricity. The COE for the stand-alone DG system is 0.206 $/kWh, which is 69.90% higher than that of the PV/SCFC system. The PV/SCFC system is cheaper than grid extension. This study opens the way for using a fuel cell as an effective method for solving the energy intermittence/storage problems of renewable energy sources.

Osmotically assisted reverse osmosis (OARO): Five approaches to dewatering saline brines using pressure-driven membrane processes

The ability of osmotically assisted reverse osmosis to draw water from concentrated brine (>75 g/L) can be attributed to the combined effect of reducing the transmembrane osmotic pressure difference via a draw solution, and operating at high hydraulic feed pressures. This approach has been incorporated into a standard ultrafiltration and reverse osmosis desalination plant to increase the process recovery. In total, five different OARO integrated flow processes are modelled numerically to determine their technical and economical feasibility in maximising the process recovery. Three of the five presented OARO integrated flow processes are novel, and offer technical and economical advantages over the previously proposed OARO processes.At lower feed salinities, OA-5, which is a new process, is the optimal OARO integrated flow process. Recoveries of up to 72% from a 35 g/L saline feed are possible when operating at the membrane burst pressure of 48.3 bar. Furthermore, the energy consumption of OA-5 is approximately 4.00 kWh/m3, which is significantly lower than that in currently employed high recovery thermal processes, such as mechanical vapour compression.OA-3 is another original OARO integrated flow process and is the most attractive at a higher feed salinity of 70 g/L. The maximum recovery of 44% is achieved at an average energy consumption of 6.37 kWh/m3. The results presented in this article demonstrate that pressure-based membrane processes can competitively concentrate brine streams to concentrations of up to 125 g/L.

Demineralization of brackish surface water by reverse osmosis: The first experience in Morocco

Desalination technique is among the focused theme of the Moroccan kingdom’s universities. The implementation of reverse osmosis (RO) technology at the industrial level has proved that this RO technology delivers an affordable production of good water quality and quantity. The conception of mid-size to large RO (FILMTEC™ product) desalination plants are performed by means of reverse osmosis system analysis (ROSA) software. This study shed the light on how realistic the predictions are done by means of ROSA software to the real daily performance of the RO (FILMTEC™XLE440) membranes. The results obtained are then compared against the real industrial data collected from Khenifra desalination plant. This RO plant is designed to produce 36.290 m3/d of drinking water at the horizon of the year 2030. The performances collected are the pressure, temperature, permeate flow and permeate conductivity. The brackish water RO desalination plant has operated successfully and showed a steady behavior from the second half of 2013. The data collected within around 400 days showed that the ROSA modeling prediction matches in a conservative way to the real performance data collected from the plant at about 97%.

Whale optimisation algorithm-based controller design for reverse osmosis desalination plants

In this contribution, whale optimisation algorithm (WOA)-based controllers are presented for reverse osmosis (RO) desalination plants. Two proportional-integral-derivative (PID) controllers are designed for flux and conductivity of RO plant model. The tuning of these controllers is carried out with a newly proposed algorithm, i.e., WOA. The minimisation of integral-of-squared-error (ISE) is considered as performance index for design of objective function in the problem. The performance of proposed controllers is compared with other optimisation algorithms-based controllers. Simulation results show the supremacy of WOA-based controllers over the other controllers. The proposed controllers are found best for RO desalination plants in terms of control of RO unit model.

Reuse of Reverse Osmosis Membranes - Case Study: Tajoura Reverse Osmosis Desalination Plant (Technical Note)

Libya is currently experiencing a major challenge in water supply due to reduction in the groundwater, especially around the coastal region. This problem is likely to create challenges for drinking water supply and the agricultural sector. Environmental desalination technology and wastewater treatments could provide a solution to the problem. In Libya, there are approximately 21 operating desalination plants, with a total capacity of 525,680 m3/d. The Tajoura desalination plant is one of the oldest reverse osmosis (RO) desalination plants established on the west coast of Liby. It has been under operation for three decades with no significant attention to these systems. Membranes used in Tajoura plant were not regularly checked or replaced on time. This paper reviews the history of membranes used in Tajoura plant since its installation, specifically storage methods and the number of damaged membranes. Finally, alternative options for reuse of used membranes are proposed. It was found that a couple of reuse options are possible for some membrane elements. Converting the fiberglass of the outer casing into small pieces or powder for other production is highly recommend, while polypropylene spacers provide good opportunities for domestic and agricultural applications.

Optimal and Economic Evaluation of a Stand-alone Microgrid for Electricity and Water Supply for Namibia’s Rural Village

Stand-alone microgrid hold a primary solution for electricity and water supply in remote areas access to National grid is not possible. This paper presents a detailed optimal sizing and economic evaluations of a stand-alone microgrid for a remote village (Amarika) in Namibia. Several renewable energy sources such as wind turbines and photovoltaic arrays were considered with a battery backup storage system and a reverse osmosis desalination plant for water supply. Modelling of the microgrid was done based on the meteorological data, the daily water and energy demand of the village. Particle swarm optimization was employed for the system techno- economic optimization: to determine a suitable microgrid configuration that can be established at minimum cost. Sensitivity analysis of the system was performed to examine the effect of variation of LPSP on LCOE. The results demonstrate that the optimized microgrid configuration and the optimization algorithm are effective and can be adopted in supplying power and water to the village. The levelized cost of electricity proves the economic feasibility of the microgrid. The levelized cost of electricity falls within a 90% standard deviation (σ=0.065) of the mean. This proved to be economically feasible with a 96.5% reliability of power supply.

Retrofitting assessment of a full-scale brackish water reverse osmosis desalination plant with a feed capacity of 600 m3/d

Retrofitting assessment of a full-scale brackish water reverse osmosis desalination plant with a feed capacity of 600 m3/d

Hydrochemical Characterization of Water Resources From Reverse Osmosis Desalination Plants

The desalination of the brackish waters is a technology of coexistence with the semi-arid and its adoption implies in determining the environmental impacts due to the reject brine generated. Therefore, this work evaluated the hydrochemical characteristics of well water (feed water), drinking water (purified) and reject brine from reverse osmosis desalination plants in Western Meso-region, Rio Grande do Norte state, Brazil. During the periods between October 2013 and November 2014, four water samples were taken at seven inland desalination plants in communities and rural settlements. The hydrochemical characteristics of the waters were evaluated using multivariate statistical analysis. The following physico-chemical parameters of water collected were evaluated: electrical conductivity (ECw), pH, concentrations of cations (sodium, potassium, calcium and magnesium) and anions (chloride, carbonate and bicarbonate), Sodium Adsorption Ratio, Langelier Saturation Index, Stability Index of Ryznar, and the Calcium/Magnesium ratio. Well water and reject brine were classified into six groups, while purified water was classified into seven groups with different levels of risk of salinization, sodification and ions toxicity.

Techno-Economic Feasibility Study of a Hypersaline Pressure-Retarded Osmosis Power Plants: Dead Sea–Red Sea Conveyor

In this study, three pressure retarded osmosis (PRO) power plants are proposed to be built on the Red Sea–Dead Sea (RSDS) water conveyance project, to generate power from the salinity gradient between two water streams at different salt concentrations. The first two proposed plants are to be built after sea water reverse osmosis (SWRO) desalination plants, where Red Sea water and the rejected brine from SWRO plants are used as feed and draw solutions, respectively. In the third proposed plant, Red Sea water and Dead Sea water will be used. Results showed that the three proposed plants are technically feasible while the third plant is the only one that is economically feasible with a 134.5 MW capacity and a 0.056 $/KWh levelized cost of electricity (LCE). The power generated from the third PRO power plant accounts for about 24.7% of the power needed for the RSDS project that can be used to power SWRO-2 in order to reduce the electricity consumption by 49.3%. If the generated power from the proposed PRO plant is sold to the Jordanian national electricity grid at the current selling price in accordance with Jordanian prices of electricity, a saving of about 21.2% can be attained. It is found that using the power generated by the current proposed plants for desalination project purposes will significantly reduce the price of desalinated water produced from SWRO desalination plants.

Reduction of water cost for an existing wind-energy-based desalination scheme: A preliminary configuration

One possible contender to replace conventional reverse osmosis schemes is an energy solution where inexhaustible resources work together with a reverse osmosis plant. Based on the experience of an existing wind-powered desalination scheme run for more than 15 years by Soslaires Canarias S.L., the final objective of this paper is to propose improvements to the scheme so as to achieve a reduction in the cost of water (through restrained capital expenses) for the sake of greater feasibility and efficiency. The cost of the scheme is evaluated assuming a combined use of a reverse osmosis desalination plant and wind energy, using, for this purpose, the (exclusive) information provided by the industrial partner. Results showed that by carrying out the actions suggested in this paper, this scheme would be able to reduce its cost of water (COW) by about 0.022 EUR per cubic meter for the current LCOE of wind turbine technology in the study area (about 6 c€/kWh for the southeast of the island of Gran Canaria, Spain). This would mean that with an additional total capital investment cost of 196 000 € (from the current scheme of Soslaires Canarias S.L.), and supposing an average membrane life expectancy of 10 years for the current state-of-the-art membranes, a net present value of 74 360.95 €, a profitability index of 1.3794, and a 224.4881% internal rate of return would be achieved.

Studies into the mass transfer and energy consumption of commercial feed spacers for RO membrane modules using CFD: Effectiveness of performance measures

Different approaches have been reported in the literature that aim to improve the performance of reverse osmosis (RO) desalination plant operations, attempting to make the desalination process more efficient.This study investigates the performance of four commercial feed spacers for spiral wound reverse osmosis modules by considering energy consumption and production capacity, as well as their combination, through a previously proven approach to computational fluid dynamics (CFD) modelling.Among the performance measures studied, SCE (spacer configuration efficacy), SPC (specific power consumption) and Pn (power number) showed a high level of predictability (R2≥0.998, 0.994 and 0.994, respectively) through power law correlations of Re with two spacer-dependent parameters. Of the four commercial spacers investigated, the DelStar Technologies Naltex N05013_90HDPE-NAT (“90 HDPE”) spacer has been ranked as the best or second best based on multiple performance measures over the flow range Re=50–100. Furthermore, the very weak response to flowrate changes observed for 90 HDPE, based on pressure loss, SPC, Pn, Sh and SCE measures, indicates the prospects for energy savings. SPMP′, a modified definition of SPMP (Spacer Performance Ratio), shows no consistent response to flow variations for the spacers studied.

Marine Current Energy Converters to Power a Reverse Osmosis Desalination Plant

Some countries are facing issues on freshwater and electricity production, which can be addressed with the use of renewable energy powered desalination systems. In the following study, a reverse osmosis desalination plant powered by marine current energy converters is suggested. The marine current energy converters are designed at Uppsala University in Sweden, specifically for utilizing low water speeds (1–2 m/s). Estimations on freshwater production for such a system, in South Africa, facing the Indian Ocean was presented and discussed. It is concluded that the desalination plant cannot by itself supply freshwater for a population all the time, due to periods of too low water speeds (<1 m/s), but for 75% of the time. By using ten marine current energy converters, each with a nominal power rating of 7.5 kW, combined with a reverse osmosis desalination plant and water storage capacity of 2800 m3, it is possible to cover the basic freshwater demand of 5000 people. More studies on the hydrokinetic resource of the Western Indian Ocean, system cost, technology development, environmental and social aspects are necessary for more accurate results.