Reverse Osmosis Desalination Plant Research Articles

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

Iran has faced with water scarcity problem for a long time. There is a strong tendency to desalinate seawater from Oman or the Caspian Sea as intake seawater and transfer it to central parts of the country. These projects face significant technical, economic, and environmental challenges. In this work, utilizing available economic theories about single-stage reverse osmosis (RO) desalination plants, the cost analysis of a conceptual plant with a production capacity of 200,000 m3/day, was accomplished assuming the use of Oman and Caspian seawater as feed. The effect of important parameters such as applied pressure, recovery ratio, total salt content of the feed, and produced water and the temperature has been studied theoretically. The results show that under the same working conditions, the final product price per cubic meter of freshwater from the Caspian Sea is $ 0.69 versus $ 1.24 for the Oman Sea, which is about 50% cheaper. The lower salinity of the Caspian Sea compared to the Oman Sea is the main reason, which lead to reduce in the capital cost of the RO membrane (62% difference), cost of the intake and pretreatment (20%), and cost of membrane elements replacement (13%) regardless of water transfer cost.

Smart system management and techno‐environmental optimal sizing of a desalination plant powered by renewables with energy storage

The present study assessed the performances of a brackish water reverse osmosis desalination unit powered by (PV/Wind/Battery) system with hydraulic storage. The hybrid renewable energy system and the reverse osmosis desalination plant were modeled for a specific site in southern Tunisia using real meteorological and water consumption data for 1 year. A total of 8760 simulations were treated under a dynamic simulator coupled to a smart energy management strategy to reach the hourly water load demand. Although the recognized reliability of the hybrid renewable sources compared to one- power source, their design may still critical. Therefore, in this paper, the authors suggest applying the methodology of optimizing the presented unit using an integrated systemic meta-modeling which is built through the design of experiments tool and defined by an equation involving the decision variables of the optimization as its parameters. This equation outlines the objects of the optimum sizing. The selected optimal design of the proposed unit is predicted by the genetic algorithm NSGA-II based on minimizing two objectives in conflict: Embodied energy and hydraulic loss of power supply. The CPU time of the NSGA-II optimization via the meta-model reached only 15 minutes of treatment (with one day to build the design of experiments) compared to the classic optimization via dynamic simulation. The results of the optimum sizing show that it is possible to consider a low water shortage rate (0% ⩽ LPSP-H < 5%) for a marginal variation of embodied energy rate which does not exceed (7%).

Performance Prediction of a Reverse Osmosis Desalination System Using Machine Learning

One of the major challenges that membrane manufacturers, commercial enterprises and the scientific community in the field of membrane-based filtration or reverse osmosis (RO) desalination have to deal with is system performance retardation due to membrane fouling. In this respect, the prediction of fouling or system performance in membrane-based systems is the key to determining the mid and long-term plant operating conditions and costs. Despite major research efforts in the field, effective methods for the estimation of fouling in RO desalination plants are still in infancy, for example, most of the existing methods, neither consider the characteristics of the membranes such as the spacer geometry, nor the efficiency and the day to day chemical cleanings. Furthermore, most studies focus on predicting a single fouling indicator, e.g., flux decline. Faced with the limits of mathematical or numerical approach, in this paper, machine learning methods based on Multivariate Temporal Convolutional Neural networks (MTCN), which take into account the membrane characteristics, feed water quality, RO operation data and management practice such as Cleaning In Place (CIP) will be considered to predict membrane fouling using measurable multiple indicators. The temporal convolution model offers one the capability to explore the temporal dependencies among a remarkably long historical period and has potential use for operational diagnostics, early warning and system optimal control. Data collected from a Desalination RO plant will be used to demonstrate the capabilities of the prediction system. The method achieves remarkable predictive accuracy (root mean square error) of 0.023, 0.012 and 0.007 for the relative differential pressure and permeates Total Dissolved solids (TDS) and the feed pressure, respectively.

SHMP as Antiscalant for Treating Brackish Water using Reverse Osmosis

One of the most genuine issues found in desalination utilizing reverse osmosis (RO) is concentrate or administration of brine. This concentrate can be utilized as a raw material for production of minerals. The antiscalants present in the RO handle ought to be removed after the process of salt crystallization. The precipitation of the amount of sulfate and carbonate from calcium can be modulated by the antiscalants in the process of reverse osmosis. However, the modulation of calcium phosphate has not been highlighted in literature. This gap in the literature instigated us to explore the activity of the antiscalants in the scaling of calcium phosphate in the RO blocks by a mild method. Nowadays, most RO desalination plants are utilizing phosphorus-based antiscalants to prevent scaling and to realize tall layer execution, as measured by diminished transmembrane weight, salt entry, and expanded saturate stream. In any case, phosphorus antiscalants in brine disposal can be an natural issue that ought to be considered and considered when introducing a desalination plant. Sodium Hexametaphosphate (SHMP) is reckoned excellent antiscalant agent which utilizes to deal with scaling in RO films. The sodium hexametaphosphate solution is prepared by mixing in sodium hexametaphosphate vessel and dosed to the feed water through. However, the apparatus containing sodium hexametaphosphate was highly prone to contamination by bacteria. The amount of bacteria within the apparatus after 36 days of makeup was far too high to be analysed as it reached a value of beyond Too Numerous To Count (TNTC). The polyphosphate can be transformed into orthophosphate in presence of sodium hexametaphosphate solution. The conversion is influenced by parameters like temperature, concentration and different nutrients responsible for the growth of microbes. Thus a study was conducted for the detection of free phosphate in a solution of sodium hexametaphosphate. Since hydrogen sulfide (H2S) can be generated in raw water, the use of chlorine was averted completely. The tanks and injection lines containing sodium hexametaphosphate solution was disinfected using sodium metabisulfite (SBS). The optimum concentration of sodium metabisulphate solution required for sterilization along with reducing the formation of the free phosphate was studied. The reaction of the SBS in the apparatus containing sodium hexametaphosphate solution was studied. Furthermore the interaction between the SBS with the sodium hexametaphosphate solution in connection with the Microguard Filter (MGF) influencing the efficacy and output of the RO system was studied.

Modeling, simulation, and optimization of the membrane performance of sea-water reverse osmosis desalination plant using neural network and fuzzy based soft computing techniques

Modeling, simulation, and optimization of the membrane performance of sea-water reverse osmosis desalination plant using neural network and fuzzy based soft computing techniques

Development of Lora P2P Network for Autonomous Seawater Quality Monitor for Green Powered Desalination Project

Scarcity of freshwater pushes countries impacted by climate change to investigate new sources of supply. Desalination plants powered by renewable energy can be the solution for a tropical developing country. Collection and treatment of seawater to produce freshwater generate an imbalanced water mass. In the case of a Reverse Osmosis Desalination Plant which pumps seawater to produce freshwater and brine as waste, the most important factor is the seawater quality, only available by observation. The design of a plant and its execution will depend on factors such as ambient temperature, salinity, and TDS. The main needs for a good multi-probe marine observation system are low energy consumption, simple monitoring, and coverage of a large area. For the sake of autonomy and ease of use, a functional and robust circuit can be set up using calibrated probes, micro-controllers, and small programmable boards. The use of programmable boards and connected probes are set up as network ‘nodes’ to send in-situ data measured from the water body. These nodes send the data using radio signal with LoRa protocol to a ‘gateway’ to store or transfer them. The parameters were measured at different time intervals, water depths, and distances from the coastline to observe how said factors affect the measurements. The results from the data collected are used to compare ocean modelling and satellite data. We present in this study the implementation of a long-range wireless autonomous sensor network and first validation tests in Jamaica and how it fills lack of information for a desalination project. Results indicate a good correlation between measure, modelling, and remote sensor. LoRa P2P network allows at an affordable price continuous monitoring of remote areas with great autonomy and resilience; results showed a successful transmission of &gt; 80% within the network.

Assessment of hybrid renewable energy systems to drive water desalination plant in an arid remote area in Jordan

ABSTRACT Jordan is relatively poor in conventional energy resources and it is dependent on foreign energy sources to cover its energy needs. At the same time the low percentage of freshwater along with the rapidly growing population urge to drag the attention to water desalination. This study presents an investigation and assessment of renewable energy resources to operate a reverse osmosis desalination plant located in arid remote area Sail El hasaa, Jordan with a capacity of up to 100 m3 of daily. The HOMER Hybrid Optimization Model Tool has been used to create optimal designs for these renewable energy systems. The photovoltaic system, wind turbine system, diesel generator, and hybrid system are evaluated in terms of each system’s net present cost and cost of energy. Different configurations are suggested for each system and compared to meet the analysis requirements. Results showed that the hybrid system is the most optimum system with the configuration of photovoltaic modules, diesel generator, wind turbine, and DC/AC converter.

Water Supply: RO Desalination Versus Conventional Water Treatment

Water scarcity threatens the health and development of countries worldwide due to the rapid expansion of population and climate change, pushing the government to find more innovative and sustainable ways to address water stress. Governments have adopted reverse Osmosis (RO) seawater desalination technology for its cheap raw water intake and stability. However, its environmental and financial sustainability remains disputable. In this study, three metrics, carbon footprint, cost, and waste discharge, are defined and analyzed to identify which water supply technology has greater prospects. Accounting for a full water treatment process from raw water intake to transportation and distribution, the RO desalination plant outruns traditional water treatment facilities due to less carbon emission, limited operation cost and maintenance, and less hazardous waste discharge. The qualitative and quantitative analysis of environmental and financial sustainability of existing solutions to the water supply may provide a more comprehensive understanding and further supports policy making.

Enhanced hydraulic cleanability of biofilms developed under a low phosphorus concentration in reverse osmosis membrane systems

A critical problem in seawater reverse osmosis (RO) filtration processes is biofilm accumulation, which reduces system performance and increases energy requirements. As a result, membrane systems need to be periodically cleaned by combining chemical and physical protocols. Nutrient limitation in the feed water is a strategy to control biofilm formation, lengthening stable membrane system performance. However, the cleanability of biofilms developed under various feed water nutrient conditions is not well understood.This study analyzes the removal efficiency of biofilms grown in membrane fouling simulators (MFSs) supplied with water varying in phosphorus concentrations (3 and 6 μg P·L-1 and with constant biodegradable carbon concentration) by applying hydraulic cleaning after a defined 140% increase in the feed channel pressure drop, through increasing the cross-flow velocity from 0.18 m s-1 to 0.35 m s-1 for 1 h. The two phosphorus concentrations (3 and 6 μg P·L-1) simulate the RO feed water without and with the addition of a phosphorus-based antiscalant, respectively, and were chosen based on measurements at a full-scale seawater RO desalination plant. Biomass quantification parameters performed after membrane autopsies such as total cell count, adenosine triphosphate, total organic carbon, and extracellular polymeric substances were used along with feed channel pressure drop measurements to evaluate biofilm removal efficiency. The outlet water during hydraulic cleaning (1 h) was collected and characterized as well. Optical coherence tomography images were taken before and after hydraulic cleaning for visualization of biofilm morphology.Biofilms grown at 3 μg P·L-1 had an enhanced hydraulic cleanability compared to biofilms grown at 6 μg P·L-1. The higher detachment for biofilms grown at a lower phosphorus concentration was explained by more soluble polymers in the EPS, resulting in a lower biofilm cohesive and adhesive strength. This study confirms that manipulating the feed water nutrient composition can engineer a biofilm that is easier to remove, shifting research focus towards biofilm engineering and more sustainable cleaning strategies.

Experimental and Analytical Study of A Reverse Osmosis Desalination Plant (Dept.M)

Due to the continuously increasing demand for fresh water in the desert and remote areas, the development of non-conventional water resources in Egypt is essential. The most advanced and promising desalination system is the reverse osmosis (RO) system. In this paper, a 5000 m3/day RO desalination plant in the city of Nuweiba in Sinai, Egypt is taken as a case study. The measured data of the plant are recorded during 5 years of its normal operation. Also, experimental tests are carried out on site to investigate the influence of the main design and -operating parameters on the plant performance. The RO system is found to be sensitive to the variation in the feed water temperature, pressure and salinity. The used maintenance schedule is also seen to be suitable for the plant, since the change in plant performance during the operation period is not noticeable. On the other hand, a cost analysis is carried out on the RO plant components. The major factors affecting the cost of product water of this plant are the power consumption and capital cost. Surprisingly, the chemical treatment cost is one of the lowest in percentage. In this case, the power consumption cost is 35.1% and the capital cost is 33.6% and that of maintenance and repairs represent only 4.9% while the chemical treatment represents 10.6% of the total cost.

Self-Learning Salp Swarm Optimization Based PID Design of Doha RO Plant

In this investigation, self-learning salp swarm optimization (SLSSO) based proportional- integral-derivative (PID) controllers are proposed for a Doha reverse osmosis desalination plant. Since the Doha reverse osmosis plant (DROP) is interacting with a two-input-two-output (TITO) system, a decoupler is designed to nullify the interaction dynamics. Once the decoupler is designed properly, two PID controllers are tuned for two non-interacting loops by minimizing the integral-square-error (ISE). The ISEs for two loops are obtained in terms of alpha and beta parameters to simplify the simulation. Thus designed ISEs are minimized using SLSSO algorithm. In order to show the effectiveness of the proposed algorithm, the controller tuning is also accomplished using some state-of-the-art algorithms. Further, statistical analysis is presented to prove the effectiveness of SLSSO. In addition, the time domain specifications are presented for different test cases. The step responses are also shown for fixed and variable reference inputs for two loops. The quantitative and qualitative results presented show the effectiveness of SLSSO for the DROP system.

Reverse Electrodialysis: Potential Reduction in Energy and Emissions of Desalination

Salinity gradient energy harvesting by reverse electrodialysis (RED) is a promising renewable source to decarbonize desalination. This work surveys the potential reduction in energy consumption and carbon emissions gained from RED integration in 20 medium-to-large-sized seawater reverse osmosis (SWRO) desalination plants spread worldwide. Using the validated RED system’s model from our research group, we quantified the grid mix share of the SWRO plant’s total energy demand and total emissions RED would abate (i) in its current state of development and (ii) if captured all salinity gradient exergy (SGE). Results indicate that more saline and warmer SWRO brines enhance RED’s net power density, yet source availability may restrain specific energy supply. If all SGE were harnessed, RED could supply ~40% of total desalination plants’ energy demand almost in all locations, yet energy conversion irreversibility and untapped SGE decline it to ~10%. RED integration in the most emission-intensive SWRO plants could relieve up to 1.95 kg CO2-eq m−3. Findings reveal that RED energy recovery from SWRO concentrate effluents could bring desalination sector sizeable energy and emissions savings provided future advancements bring RED technology closer to its thermodynamic limit.

Feasibility analysis of wind and solar powered desalination plants: An application to islands

Economic surveillance for securing water projects driven by non-conventional energy sources is a challenge. The carrying out of these initiatives in economies based on liberalized markets faces governments against the need for guaranteed profits. As water availability has become a relevant global problem, and desalination an energy-intensive demand solution, it is common to combine both kinds of technologies, renewable energy systems and desalination plants. This research investigates the influence of grants, investment rates, and energy and water sales on the commercialization of two desalination technologies. A performance analysis has been carried out taking into account different scenarios. Following this approach, a simulated reverse osmosis desalination plant has been compared with respect to an already granted novel pilot plant. Results show a better fulfilment of the non-economic objectives, and economically profitable not only under certain conditions of conceded grants, and investor's expected benefits but also of sales of water-energy, that highlighted as a limiting factor. The Levelized Cost of Energy might be similar than the Spanish generation means, depending on the cost escalation rate of the loans, and conceded grants. It was found a reduction of 11 euro cents under the average price that could be achieved, for the standard scenario.

Role of dissolved air flotation (DAF) and liquid ferrate on mitigation of algal organic matter (AOM) during algal bloom events in RO desalination

Harmful Algal Blooms (HABs) are considered a major contributor to membrane biofouling in Seawater Reverse Osmosis (SWRO) desalination plants. The presence of HABs in the raw feed water leads to an increase in membrane fouling rate, increase of chemical consumption, and can cause temporary shutdown of plants. Effective pretreatment can reduce the amount of organic foulants reaching the RO membrane and alleviate the problem of flux decline during RO operation and frequent membrane cleaning using chemicals. This study compared the effect of in-situ generated liquid ferrate and ferric chloride in combination with dissolved air flotation (DAF) as a pretreatment strategy to remove algal cells and algal organic matter (AOM) during algal bloom events. Experiments were performed using a bench-scale DAF unit. HABs conditions were simulated by harvesting AOM from cultivating Chaetoceros affinis (CA) in raw seawater to a concentration of around 10 mg C/L of dissolved organic carbon (DOC). The liquid ferrate was generated in-situ by wet oxidation of ferric chloride in an alkaline media. The best performance was achieved with the combined use of liquid ferrate and DAF, removing up to 100% of algal cells, 99.99% of adenosine tri-phosphate (ATP), and up to 92% of AOM.

Optimal design of energy sources and reverse osmosis desalination plant with demand side management for cost-effective freshwater production

Reverse osmosis desalination plants running with renewable energy-based microgrids are gaining importance. A new approach for the design of microgrid with a reverse osmosis desalination plant system called coordinated sizing is proposed in this manuscript. The proposed algorithm is a leader-follower structured optimization process. The desalination plant is segregated as units and each unit can be operated independently as required. A direct load control-demand side management is incorporated into the sizing process to determine the optimal flexible operation of the desalination plant and microgrid's power dispatch simultaneously. A conceptual microgrid powering desalination plant is considered to evaluate performance of the proposed coordinated sizing method. Different evolutionary algorithms are applied for solving the sizing problem and the results are analyzed. The proposed coordinated sizing method is compared with the conventional sizing method. With and without the flexible operation of desalination plant cases are considered to compare economy of the plant. The results demonstrate that the proposed coordinated sizing is cost-effective and provide better operational flexibility.

Waste heat cascade utilisation of solid oxide fuel cell for marine applications

To cope effectively with the world’s energy shortage and environmental pollution, a fuel cell combined with waste heat recovery technology has gradually become the best option for large ship power generation equipment. In this investigation, a combined system comprising a solid-oxide-fuel-cell-gas-turbine subsystem, supercritical carbon dioxide cycle, organic Rankine cycle, ammonia-water absorption refrigeration cycle, and high-pressure reverse osmosis desalination plant is introduced and analysed. Not only the power output of the system is calculated, but also the contribution of cold energy is considered by calculating its equivalent power. The results illustrate that the equivalent net output and thermal efficiency of the system are 278.82 kW and 67.03%, respectively. Compared with the solid oxide fuel cell, the power output increases by 86.35 kW and the fuel efficiency increases by 20.7%. Additionally, the system can provide 5.95 kW of cold energy and 0.94 m3/h of fresh water for the crew under the condition of maximum power output. To summarize, the proposed novel system design can realize the combined production of cold energy, electric energy, and fresh water, and it exhibits the characteristics of high efficiency and cleanliness.

Optimal sizing and techno-enviro-economic feasibility assessment of large-scale reverse osmosis desalination powered with hybrid renewable energy sources

Seawater desalination is a viable source of potable water, particularly for the coastal and remote areas. However, their sustainability is limited by the intensive energy demand of the present methods. Renewable energy is an inexhaustible source of energy, accompanied by cost reduction benefits and clean power generations. Seawater desalination powered with renewable energy sources is being attractive, mainly if the utility-grid is absent. This paper aims to design a renewable energy system, to meet the electrical load demand of large-scale reverse osmosis desalination plant (1500 m3/d), and to find the optimal sizing and techno-economic and environmental feasibility assessment of several off-grid power systems. Two off-grid scenarios with different combinations of hybrid power systems were proposed and compared with the base-case of diesel. The first scenario consists of a photovoltaic, wind turbine, diesel, and generator, while the second scenario is equipped with battery storage devices. A total of eleven hybrid renewable energy systems were modelled, analyzed, and compared with the aid of HOMER Pro software to identify the best performance and the optimal plan configuration. The optimization results show that the proposed photovoltaic/wind/diesel/battery/convertor system outperformed the other alternatives and exhibited reduction potential of 60.7%, 73.7%, 62% and 81.5% lower than the existing diesel with regards to the net present cost, renewable fraction, cost of energy, and carbon dioxide emission, respectively. The optimum case consists of 451 kW solar panels, 25 wind turbines, 250 kW diesel power, battery storage of 352 string, and 358 kW system converter. The results obtained by the optimal plan with low cost and environmental protection aspects would provide a new sight for real field applications of large scales reverse osmosis applications.

Fault Detection and Isolation System Based on Structural Analysis of an Industrial Seawater Reverse Osmosis Desalination Plant

Currently, the use of industrial seawater reverse osmosis desalination (ISROD) plants has increased in popularity in light of the growing global demand for freshwater. In ISROD plants, any fault in the components of their control systems can lead to a plant malfunction, and this condition can originate safety risks, energy waste, as well as affect the quality of freshwater. This paper addresses the design of a fault detection and isolation (FDI) system based on a structural analysis approach for an ISROD plant located in Lima (Peru). Structural analysis allows obtaining a plant model, which is useful to generate diagnostic tests. Here, diagnostic tests via fault-driven minimal structurally overdetermined (FMSO) sets are computed, and then, binary integer linear programming (BILP) is used to select the FMSO sets that guarantee isolation. Simulations shows that all the faults of interest (sensors and actuators faults) are detected and isolated according to the proposed design.

Recovery of salinity gradient energy in desalination plants by reverse electrodialysis

Salinity gradient energy (SGE) capture by reverse electrodialysis (RED) is an emerging technology to advance the phaseout of conventional water-intensive energy sources in desalination industry. This paper assesses SGE recovery potential of an up-scaled RED system in seawater reverse osmosis (SWRO) desalination plants. Using a detailed RED system's model (i) we conducted a parametric evaluation of feed's concentration, feed's flow rate, and temperature to identify the optimal working conditions of an industrial-scale RED unit; (ii) we estimated SGE recovery of a RED plant in SWRO plants distributed worldwide, adopting a single-stage arrangement of the RED units; (iii) finally, to enhance energy yield, we examined different RED plant's layouts in a specific SWRO plant. The results underline the merits of this modelling tool to assist SGE-RED implementation in the utmost scenarios. Regarding RED plant's layout, findings reveal that the series-parallel arrangement of the RED units improves the power output and energy yield of the system but requires more RED units. Hence, a systematic evaluation through optimization of the hybrid process's configuration both at plant's scale and at RED unit's scale is needed to properly determine RED's SGE recovery potential from waste streams in SWRO plants.

Energy supply of a large size desalination plant using wave energy. Practical case: North of Gran Canaria

This research analyses the feasibility of supplying the energy demand of a grid-connected large size desalination plant by wave energy. One drawback of the wave technology is that it is not yet fully commercial and, therefore, many different technologies are available. Different arrays of wave energy converters have been selected for this study, comprising different type of technologies and technical characteristics. Two scenarios have been deployed, one based on wave energy and another one that combines wave energy and solar photovoltaic energy. The hourly analysis shows the matching between demand and supply. The aim is to establish if solar photovoltaic energy can improve the hourly matching between demand and production. The methodology proposed has been applied to a practical case which is a 15,000 m3/day reverse osmosis desalination plant located in the North of Gran Canaria, whose annual energy demand is 19 GWh per year. Results show that most of the wave devices selected are able to meet the yearly energy demand of the desalination plant although there are significant differences depending on the wave technology and in the hourly analysis. The combination of photovoltaic and wave energy improves the hourly matching in some cases but not in all. Thus, an hourly analysis of the specific technology is needed in each case.