Water Reverse Osmosis Desalination Plant Research Articles

Long-Term Performance Evaluation and Fouling Characterization of a Full-Scale Brackish Water Reverse Osmosis Desalination Plant

Water scarcity in Tunisia’s semi-arid regions necessitates advanced brackish water desalination solutions. This study evaluates the long-term performance and fouling characteristics of the largest brackish water reverse osmosis desalination plant in southern Tunisia over a period of 5026 days. The plant employs two-stage spiral-wound membrane elements to treat groundwater with a salinity of 3.2 g L−1. The pre-treatment process includes oxidation, sand filtration, and cartridge filtration, along with polyphosphonate antiscalant dosing. Membrane performance was assessed through the analysis of operational data, standardization of permeate flow (Qps) and salt passage (SPs), and the calculation of water (A), solute (B), and ionic (Bj) permeability coefficients. Over the operational period, there was an increase in operating pressure, pressure drop, and permeate conductivity, accompanied by a gradual increase in SPs as well as in the solute B and ionic Bj permeability coefficients. The average B increased by 82%, reflecting a decrease in solute rejection over time. Additionally, the ionic permeability coefficients for both SO42− and Cl− ions increased, with Cl− showing an 88% increase and SO42− showing an 87% increase. The produced water’s salinity increased by 67%, indicating a significant loss of membrane performance. To identify the cause of these problems, membrane characterization was analyzed using visual inspection, X-ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR). The characterization revealed the complex nature of the foulants, with a predominant presence of calcium sulfate, along with minor quantities of calcite, dolomite, and silica. The extent of CaSO4 deposition suggests poor antiscaling efficiency, highlighting the critical importance of selecting an effective antiscalant to mitigate membrane fouling.

Pumping-Induced Feed Water Quality Variation and Its Impacts on the Sustainable Operation of a Brackish Water Reverse Osmosis Desalination Plant, City of Hialeah, Florida, USA

Brackish water reverse osmosis (BWRO) desalination of groundwater is believed to be a sustainable method of providing municipal utilities with a high-quality supply in regions where freshwater sources are stressed and not sustainable. A key aspect of water management is the ability to evaluate an aquifer containing brackish water to ascertain future pumping-induced water quality changes and their impacts on the facility operation and economics. The city of Hialeah, Florida, has operated a BWRO facility for the last 9 years. The facility has a maximum design capacity of about 88,000 m3/d but is currently operating at about 33,000 m3/d. The facility was designed to treat water with a TDS of up to 10,000 mg/L. A detailed hydrogeologic investigation, including groundwater solute-transport modeling, suggested that the salinity of the source water would remain under 10,000 mg/L of TDS during the 30-year life expectancy of the facility. However, after 9 years of operation, it was found that the rate of salinity increase was much higher than predicted (27.5%), at the low rate of 33,000 m3/d. If the faculty was operated at the maximum capacity, the ability of the plant to treat the source water might be between 5 and 10 years. The conceptual model used to guide the solute transport modeling was not accurate for this site because it did not incorporate the apparent enhanced leakance through the basal confining unit below the aquifer. The greater leakance was likely caused by undetected, irregularly distributed fracturing of the underlying confining dolostones. The facility will require a major redesign to upgrade the process to be able to treat seawater at a TDS significantly above 10,000 mg/L in the future, should that occur. While the change will be costly, with a high capital cost to change the process, increased energy consumption, and overall higher water treatment cost, it is still more sustainable and has less environmental impact compared to other alternatives (e.g., treating tidal sources of seawater). The use of electricity from nuclear or solar generation could mitigate the environmental impacts of higher power consumption.

Decentralized brackish water reverse osmosis desalination plant based on PV and pumped storage - Technical analysis

Photovoltaic driven decentralized reverse osmosis plants for brackish water desalination offer a sustainable and low-emission solution for water deficiency problems, especially in arid and semi-arid regions. However, the primary challenge for this combination is how a brackish water reverse osmosis desalination (BWRO) plant based on photovoltaics (PV) can be operated continuously with high energy efficiency. Therefore, this study presents an innovative concept for a BWRO plant operated 24 h/d with a constant drinking water production capacity based on PV and pumped storage as hydraulic energy storage. The latter is used to cover the hydraulic energy consumption of the BWRO process completely or partially in times when the necessary electrical power cannot be provided by the PV plant due to missing solar radiation. During the course of the year, only 2% of the hydraulic energy to be stored in the pumped storage is lost during charging and discharging. The overall efficiency (from PV electricity to used hydraulic energy) of the pumped storage in the investigated innovative system is 78.4%. This value is 2.4% higher than the overall efficiency for a battery system with a high pressure pump in the current designs for BWRO based on PV and battery.

Enhanced exergy analysis of a full-scale brackish water reverse osmosis desalination plant

Brackish water desalination by reverse osmosis membranes is energy-driven process. With the purpose of improving the energy performance of such unit a full-scale BWRO desalination plant located in Canary Island (Spain) has been working under intermittent operating conditions for 14 years was assessed with conventional and enhanced (exogenous and endogenous/avoidable and unavoidable exergy destructions) exergy analysis. The exergies across the major components of the plant are calculated. The conventional exergy analysis reveals that, largest irreversibilities were identified in the RO system (membrane modules), the high pressure pump and the feed pump which amounts to about 64.28%, 40.84% and 38.48% respectively. Results of advanced exergy analyses shows that 70.61%, 92.94% and 7.83% of the total exergy destruction in the high pressure pump, feed pump and the RO system respectively are avoidable. Moreover, the highest endogenous avoidable exergy destruction rate was determined owing to the feed and high pressure pumps. Using these findings, instructions were proposed to ensure optimal effectiveness of the RO system and to improve the exergy destruction in the pumps currently in use.

Conceptual arrangement and basic design of drinking water reverse osmosis desalination plants

To propose a conceptual arrangement of reverse osmosis desalination plants, four comprehensive decision algorithms and a software are developed. Typically, commercial software predict the performance of the reverse osmosis membranes based on their pre-determined configuration; however, the developed decision algorithms and the developed software in this study have the capability of introducing the conceptual arrangement of pretreatment units, reverse osmosis membranes, and energy recovery devices for both seawater and brackish water reverse osmosis plants. To perform a comprehensive study, alongside the developed software and the decision algorithms, both design considerations of the required equipment in pretreatment units and mathematical modeling of reverse osmosis membranes are included. Finally, to validate the accuracy of the developed decision algorithms and the software, four installed reverse osmosis desalination plants for producing drinking water from seawater and brackish water feeds are investigated. The algorithmic proposed plants for all four cases were in close agreement with the implemented industrial cases and World Health Organization standards.

Climate Change Mitigation Strategy through Membranes Replacement and Determination Methodology of Carbon Footprint in Reverse Osmosis RO Desalination Plants for Islands and Isolated Territories

This article shows a climate change mitigation strategy by means of membranes replacement and determination methodology of carbon footprint in reverse osmosis (RO) desalination plants, valid for all the islands, and even isolated territories in the continent. This study takes the case of study of Canary Islands, where there are more than 320 desalination plants with different sizes, private, and public. The objective is to propose a new method which integrates this analysis with the replacement of membranes, from 0% to 20% per year in sea water reverse osmosis desalination plants, to reduce the carbon footprint and ecological footprint. If it is considered a replacement of 20% of the elements per year, the carbon footprint could be reduced to between 5% and 6% and even more if it is introduced low energy consumption membranes instead of high rejection elements. The factor mix in Canary Islands, according to the technological structure of the generation park that uses oil products, is around 0.678 kgCO2/kWh, much higher than in the Spanish mainland where it is 0.263 kgCO2/kWh. Therefore, it is estimated in Canary Islands 5,326,963 t CO2/year can be emitted, which represents 2.4 tCO2/person/year, 12 times more the admissible admissions per inhabitant in the Canary Islands, only considering the seawater desalination sector. This document shows the different results of the analysis of energy efficiency and the environmental footprints. This study may serve as a tool for the decision-making processes related to how to improve energy efficiency in desalination plants.

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

Artificial neural networks applied to manage the variable operation of a simple seawater reverse osmosis plant

For the purpose of managing the operation of a small-scale prototype of a sea water reverse osmosis desalination plant installed on the island of Gran Canaria (Spain) and enabling it to function with fluctuating power input, artificial neural network (ANN) models were incorporated into its control system. The ANN models were developed to generate feed flow and operating pressure setpoints (with the restriction of having to maintain the permeate recovery rate within a certain range) after taking into account not only the available electrical power but also the temperature and conductivity of the feedwater.It is concluded that the ANN models that were used after training and validation were able to successfully manage the random and widely varying available electrical power. The statistical hypothesis testing that was also performed showed no significant statistical differences (at 5% level) between the errors (both MAE and MAPE) committed when adapting power consumption of the plant to the available electrical power in the various operational tests using different feedwater characteristics.

Techno-Economic Study of PV Powered Brackish Water Reverse Osmosis Desalination Plant in the Jordan Valley

Jordan is one of the ten most water scarce countries in the world. In 2014, the share of water per capita per year in Jordan is 120 Cubic Meters (m3 ). The water deficit is estimated to be 160 Million Cubic Meter (MCM) in 2015. This deficit is projected to grow up to 490 MCM by 2025. This study discusses the possibility of using solar energy for brackish water desalination in Jordan Valley (JV) to reduce the pressure on the fresh water and the conventional energy consumption associated with the desalination process, as well as, to reduce Greenhouse Gases (GHG) emissions associated with the consumption of energy produced from fossil fuels. Photovoltaic (PV) powered brackish water reverse osmosis desalination technology (RO) has been investigated in this study. The PV system has designed using PVSOL software. The economic feasibility study of use PV system has been done using Average Incremental Cost of Water (AICOW), Internal Rate of Return (IRR) and Net Present Value (NPV) in several scenarios. The results of the analysis showed that using PV systems for brackish water desalination for a small size single plant at current electricity tariff is not economically feasible for the farmers. But it is feasible for a larger size plant for ten farms or more, or with financial support from the government. The feasibility results showed that using PV systems for brackish water desalination for the government side are economically feasible even for a small size plant.

Multi objective optimization of reverse osmosis desalination plant with exergy approach

A brackish water reverse osmosis desalination plant based on exergy analysis was simulated and its performance was investigated. The computational model base on diffusion and convection transport mechanisms and concentration polarization concept was developed to predict the performance of RO membrane using different feed water concentration, feed flow rate, feed water pressure, membrane specification and feed water properties. The mathematical model has had good accuracy with reference data. The influence of operating parameters such as feed water pressure and temperature on the performance of the system was studied. Exergetic efficiency and destruction of streams exergy were calculated. Finally, multi-objective optimization for highest exergetic efficiency and permeate flow rate was done.

Long-term performance decline in a brackish water reverse osmosis desalination plant. Predictive model for the water permeability coefficient

Transport models in reverse osmosis (RO) desalination have been extensively studied taking into account various factors such as temperature, fouling, etc. However, there are not many models that describe the behavior of a desalination plant over long time periods. These models depend on operating time and empirical parameters to estimate the flux or the average water permeability coefficient (A) decline. The proposed model separates the decline of A in two stages, the first stage refers to a more pronounced decline due to initial compaction and irreversible fouling and the second stage describes a more stable period with less slope. The model is based on the superposition of two exponential functions, which depends on operating time, empirical parameters and fouling potential of the feedwater (kfp). Ten years operating data of a brackish water reverse osmosis (BWRO) desalination plant were used. The obtained results with the proposed model showed a slightly better fit than previous models, but giving meaning to two different behaviors separated in two stages.

Start-up of brackish water desalination for agricultural irrigation in the Canary Islands (Spain)

The Canary Islands are an arid region. Therefore, water resources are scarce and several islands depend strongly on the sea and brackish water desalination. Water desalination, in the water policy of the Canary Islands, has been deeply rooted in the last 40 years, allowing solving and overcoming the shortage. This article concerns the beginning of the brackish water desalination for agricultural purposes in the Canary Islands (Spain). It provides the data and experience acquired during the early years in the region; one of the authors of this paper was working in the department of desalination of the first companies in the Canary Islands like Riegocan, AM García Glez. and Temkon. These companies worked with membrane manufacturers like Fluid System, Filmtec and Desalination Systems and pressure pipe manufacturer—Advanced Structures. Fifteen brackish water reverse osmosis desalination plants were built in the Canary Islands to provide water for agricultural irrigation between 1979 and 1983. These plants had a significant impact on agriculture.

80,000 h operational experience and performance analysis of a brackish water reverse osmosis desalination plant. Assessment of membrane replacement cost

The brackish water reverse osmosis (BWRO) desalination plant has operated successfully for around 80,000h from 2004. Reverse osmosis membrane technology has improved allowing higher salt rejection, permeate water productivity and durability. But when the membranes should be replaced taking into account the energy consumption increase. The aim of this paper is to assess the operating information available and energy consumption to evaluate when it would be appropriate to replace the membranes taking especially into account the long life elements involved. The graphical evolution of feedwater conductivity, permeate conductivity, feed pressure, pressure drop, specific energy consumption (SEC) and the standardization of the permeate flow, salt rejection and SEC are shown. A comparison between specific energy consumption increase due to membrane performance decay, the regularity of chemical cleaning and membrane replacement in terms of costs has been carried out. The results show that the most effective choice for this BWRO desalination plant is not to replace the membranes in the first ten years of operation taking into account the membranes performance and the cost of electricity at the time.

Flavour assessment of blends between desalinated and conventionally treated sources

The drinking water supply in the Barcelona region has recently experienced a radical change because three new facilities with membrane technology have come into service (i.e. reverse osmosis and electrodialysis reversal in the Llobregat river and a sea water reverse osmosis desalination plant. The aim of the study was to predict the reaction of consumers to changes when blends between desalinated and conventionally treated sources were supplied. Seven blended samples of membrane and conventionally treated waters and three unblended water samples were assessed using ranking, scoring and triangle tests. Trained and untrained panels were used for taste assessment. The number of available tasters for each session was 13–14 trained tasters and between 22 and 32 volunteers. Therefore, the total number of tasters ranged between 36 and 46. Ranking and scoring results from both panels were similar (i.e. no significant difference in an independent t-Test), even though the trained panel displayed a better sensitivity in the triangle test. Water preference scores ranged from 3.6 to 6.5. Multiple comparison procedures (i.e. Fischer’s Least Significant Difference Test) on global normalised liking results allowed us to define a grouping structure for water samples that were significantly different from the others. It was determined that membranes would contribute positively to consumer perception. For the relationship between the salinity represented by the total dissolved solids (TDS) and water preference, the overall trend indicated that water with lower salinity was preferred. These results confirm that the assessment of water is primarily driven by TDS even though other factors (i.e. pH, mineral composition) can play a significant role in the liking of water, which is consistent with previously published reports.

RETRACTED: Waste energy recovery in sea water reverse osmosis desalination plants, Part-2: case study

RETRACTED: Waste energy recovery in sea water reverse osmosis desalination plants, Part-2: case study

Evaluation and characterization of seawater RO membrane fouling

Fresh water shortage is a growing problem facing the world, especially in the Middle East. With the rapid increase in fuel price, seawater reverse osmosis (SWRO) is increasingly becoming a popular option for water supply. To date several sea water reverse osmosis desalination plants have been built in the United Arab Emirates (UAE) to meet the growing demand for fresh water in the country. The Fujairah Water and Power Plant was acquired in 2006 by a joint venture company between the Abu Dhabi Water and Electricity Authority and Sembcorp, forming the Emirates Sembcorp Water and Power Company (ESWPC). The plant is operated under agreement by Sembcorp Gulf O&M Company (SGOMC). Serving as a brown field project, Sembcorp, through ESWPC Fujairah IWPP has made a commitment to supply 535 megawatts (MW) of power and 100 million imperial gallons per day (MIGD) of water, as well as an additional commitment of augmenting power supply to 760 MW from February 2009. Until 2005, the plant was the largest SWRO plant in the world. Today, after almost 5 years of operation, it is still the second largest SWRO plant worldwide and continues to provide inspiration for practical design and operational guidance for future plants. Membranes deteriorate and are replaced due to the deposition of unwanted materials on the surface. In addition, a decrease in membrane performance may be due to other factors such as degradation by chemical (oxidation, hydrolysis, etc.) and/or mechanical (compaction, telescoping) processes. Extending membrane life and thereby minimizing replacement costs are a key success factor for reverse osmosis (RO) systems. This paper explored field membrane deposition that can be termed as “membrane fouling”. Fouling as a result from foulant accumulation on the membrane surface is the major cause of RO system failure. RO membrane fouling is a complex phenomenon involving the deposition of several different but related types of foulants on the membrane surface. RO system fouling problems are becoming more prevalent as the use of low quality feed water increases. In addition, water treated with various organic chemicals pose very serious and challenging fouling problems. Operating costs increase when RO system performance deteriorates. These costs are associated with membrane cleanup, replacement, and system downtime. The success of an RO system depends largely on three factors: system design, pretreatment (e.g., chemical conditioning), and system maintenance. Therefore it is very important to evaluate the nature and extent of fouling and the characterize of the foulant. This is essential for the betterment of water treatment procedures, better selection of chemicals and modification in processes—whatever possible to extend the life of the membrane.

Energy management and DSM techniques for a PV-diesel powered sea water reverse osmosis desalination plant in Ginostra, Sicily

The aim of this project is the development of an energy management technique for a Sea Water Reverse Osmosis (SWRO) desalination plant in the small village of Ginostra in Sicily. The desalination plant has not been realised yet and only a preliminary project is available from ENEA, the Italian Agency for Energy, Environment and New Technologies [ENEA (Italian Agency for New Technologies, Energy and Environment), Impianto di Dissalazione a Ginostra, Isola di Stromboli — Progetto preliminare. Internal Project Documentation]. The energy needed to perform the desalination process will come from the 100 kWp PV-Diesel hybrid system that supplies the islanders whose installed power will be expanded to 125 kWp. This system has been sized for the energy demand of the summer months when the population is much higher. This results in the production of a large amount of excess PV energy that remains unused from October to May. The desalination system has to provide a local source of fresh water (at the moment water is periodically supplied by a tank ship) through the use of as much excess PV energy as possible. Thus, the aim of the energy management system is to run the desalinator with the smallest possible amount of diesel produced energy, and with the largest possible amount of PV excess energy. An energy management technique is here proposed and an hourly simulation of the combination of the hybrid system with the desalination plant is performed. Results for energy consumption with and without the proposed energy management technique are presented and the number of diesel operational hours has been taken as the discriminating parameter.

“Design of compact, containerized desalination plants”

On 13.8.1987 Hydrotechnik has signed a contract with the Ministry of Electricity and Water, Kuwait, for the supply, erection and commissioning of 13 Nos. containerized mobile Brackish Water Reverse Osmosis Desalination Plants with a capacity of 13 x 250.000 IGPD (or 13 x 1136 m3/day). The units, which draw brackish water from the ground water system, serve as Emergency Units for hospitals and other important government installations. Only six months after the date of signing the contract, the first Reverse Osmosis Unit, consisting of 1. one 20 feet pretreatment-filtration container 2. one 40 feet operation container and 3. one 40 feet storage container 4. two 50.000 imp. gallons raw water/product water tanks 5. complete civil work and erection had passed the initial reliability test and went into commercial operation. On 13.11.1988, 15 months after signing the contract, all 13 units have been successfuly put into operation, each unit thereby passing a 110 days reliability test. As per today, all units are operating to the satisfaction of the customer, producing drinking water with a salinity which is far below the limits of the WHO standard. For example, the first unit has a record of 9850 operation hours as per April 1988. In this paper we have outlined design considerations of these Emergency Units as well as special properties and features of the HYDROCOMPACT containerized Reverse Osmosis Desalination Units.

Design aspects of large sea water reverse osmosis desalination plants

As the size of SWRO plants grow, more attention must be paid to the overall design aspects of the total plant. Some of these are simplifying and improving the pretreatment; reducing the pretreatment chemicals; systems optimization to match sea water conditions and; component size selections. The optimum conversion ratio is generally the maximum possible as limited by brine osmotic pressure and brine flow considerations. This is from 30% to 40% depending on feed temperature and pressure. An economic analysis of cooling of the feedwater is made. This was found to be beneficial for sea water temperatures over 27°C. To utilize larger single streams or “blocks” of permeators, larger high pressure pumps should be employed. These may be driven directly by medium speed diesel engines. A block size of 5 MIGD using a single H.P. pump of 2517 m 3/h (11,080 U.S. GPM) at 701m is envisioned.

Design aspects of large sea water reverse osmosis desalination plants

As the size of SWRO plants grow, more attention must be paid to the overall design aspects of the total plant. Some of these are simplifying and improving the pretreatment; reducing the pretreatment chemicals; systems optimization to match sea water conditions and; component size selections. The optimum conversion ratio is generally the maximum possible as limited by brine osmotic pressure and brine flow considerations. This is from 30% to 40% depending on feed temperature and pressure. An economic analysis of cooling of the feedwater is made. This was found to be beneficial for sea water temperatures over 27°C. To utilize larger single streams or “blocks” of permeators, larger high pressure pumps should be employed. These may be driven directly by medium speed diesel engines. A block size of 5 MIGD using a single H.P. pump of 2517 m 3/h (11,080 U.S. GPM) at 701m is envisioned.