Brackish Water Reverse Osmosis System Research Articles

Optimizing energy efficiency in brackish water reverse osmosis (BWRO): A comprehensive study on prioritizing critical operating parameters for specific energy consumption minimization

Reverse osmosis (RO) systems offer a viable solution for treating brackish water (BW), a common but underutilized water resource. However, the energy-intensive nature of brackish water reverse osmosis (BWRO) systems poses affordability challenges to water supply, necessitating a focus on minimizing their energy consumption to support SDG6's goal of providing safe and affordable drinking water for all. This study addresses the critical need to minimize the specific energy consumption (SEC) of a typical BWRO system, defined as the energy consumed per unit of water recovered, mathematically and experimentally. Empirical models were developed proving there is a global minimum SEC while adjusting the operating conditions. Furthermore, we identified the key operating factors influencing SEC and their priority levels, along with their interactive effects. Notably, no prior study has discussed the significance and interaction of these operating factors (e.g., feed water salinity, temperature, pressure, flowrate and membrane permeability) on SEC of a BWRO system. Employing a full factorial experimental design with mixed levels of operating parameters, the study developed regression models that elucidate the mechanistic interaction between these parameters and system performance. Moreover, the models were validated experimentally, with a new dataset demonstrating their accuracy and reliability. ANOVA statistical analysis identified feed salinity, pressure, flow rate, feed flow rate×pressure, salinity×pressure, and temperature as influential operating parameters in reducing SEC, in descending order of importance. Operating within the determined optimum range resulted in a 36 % decrease in SEC and a more than fourfold increase in water recovery. The study's systematic approach and findings can be extrapolated to optimize the performance of other desalination technologies and diverse feed water types, contributing significantly to global water sustainability efforts.

Pilot study of biofouling occurrence in a brackish water reverse osmosis system using intermittent operation

Water scarcity is a severe issue for humans owing to global climate change. Water reuse via reverse osmosis (RO) has been widely used to stabilize water supplies; however, RO membrane fouling increases operational costs and necessitates intermittent operation. The biofouling study on the RO pilot was operated either intermittently or continuously using collected brackish water. The environmental microbiome was incubated under oxic and anoxic conditions to simulate surface and groundwater conditions as the feed water. The least fouling was observed on the RO membrane surface when the RO system was operated intermittently using feed water incubated under anoxic conditions. The microbial results showed that specific biofilm communities were formed on RO membrane surface after brackish water RO (BWRO) operation. The major biofilm-forming bacteria distinctively differed with influent water conditions (i.e., oxic vs. anoxic), whereas they were less different with operational strategies (i.e., continuous vs. intermittent). Intermittent operation could compensate for physical cleaning. However, chemical cleaning showed the most effective results for microbe removal on the membrane surface. Therefore, intermittent operation using anoxic feed water can mitigate fouling formation on RO membranes.

Installation of the Brackish Water Reverse Osmosis System Coupled with Solar Power for Drinking Water Production in Ben Tre, Vietnam Considering Water Usage and Cost

Recently, the unbalanced water demand and supply have been occurred globally due to the climate change, industrialization, and population increase. The water shortage problem became much severe in the developing countries because the low-stage of infrastructure might result in frequent limitation of water and transportation of water. Therefore, sustainable water supplying option is the key for the boosting the local economy. The Mekong Delta area produce most of the products in agriculture and fishery in Vietnam. However, due to low income and vast area, the infrastructure for water supply has been limited in the Mekong Delta area. Moreover, due to reduced Mekong-river flow by the dam construction in upper reaches, increased seawater level by the global warming, and increased unexpected drought and flooding by the climate change, the water supply in the Mekong delta is becoming hard. Therefore, sustainable water supplying option was required. In this study, the reverse osmosis-based desalination process could use undrinkable saline water as the feed water coupled with photovoltaic panel was suggested. In order to install the decentralized and off-grid type water production plant in the proper place in the Mekong Delta, the KIST, VKIST, and central and local governments in Vietnam collaborated. The RO plant could be successfully installed by the help of the partners and the operational conditions have been monitored. If the water providing option could be separated according to the purposes such as drinking usage and other water usage, the more technical options could be applied for the water production.

High-Throughput Optimal Design of Spacers Using Triply Periodic Minimal Surfaces in BWRO

The development of advanced feed spacers under different working conditions can enhance the performance of the reverse osmosis (RO) desalination process. The 3D-printed experimental results on triply periodic minimal surfaces (TPMS)-based spacers in previous literature indicate that the spacers have higher permeation flux of water compared to those of the common commercial spacers. In this paper, a hybrid modeling approach is developed and applied to predict and evaluate the performance of TPMS-based spacers. The effect of feed channels’ height and porosity on the performance of spacers in brackish water RO (BWRO) process is studied by using a high-throughput approach. The predicted pressure drop by new simulations using the TPMS-based spacers (≈0.09–0.27 bar) from inlet to outlet in a typical two-stage BWRO system is reduced by more than 89% than that of using the commercial spacer (≈2.57 bar). Using the designed advanced spacers, the average permeation flux of water increases more than 8.6% compared to that of the commercial one. With the increase in feed channel height and porosity, the performance of spacers is gradually improved. TPMS-based spacers have significant industrial application prospects.

Performance and cost analyses of hybrid diesel-photovoltaic powered small brackish water reverse osmosis system in Saudi Arabia

Performance and cost analyses of hybrid diesel-photovoltaic powered small brackish water reverse osmosis system in Saudi Arabia

Pilot Study of Biofouling Occurrence in a Brackish Water Reverse Osmosis System Using Intermittent Operation

Pilot Study of Biofouling Occurrence in a Brackish Water Reverse Osmosis System Using Intermittent Operation

Seawater Desalination by Using Nanofiltration (NF) and Brackish Water Reverse Osmosis (BWRO) Membranes in Sequential Mode of Operation

In this study, the applicability of nanofiltration (NF) membranes as a pretreatment prior to reverse osmosis (RO) in seawater desalination was investigated. The membranes used wereNF270 and NF90 as the NF membranes, while the brackish water (BW) RO membrane BW30 was used as the RO membrane. In desalination tests, permeates of the NF membraneswere collected and used as the feed to the BW30 membrane. The calculated permeate fluxes were 6.7 L/h.m2, 11.3 L/h.m2, 24.3 L/h.m2, and 36.6 L/h.m2 for single BW30-35 bar,NF270-30 bar + BW30-35 bar, NF90-30 bar + BW30-25 bar and NF90-30 BW30-35 bar, respectively. The calculated water recovery and rejected salt values were 51.6%, 41.4%,24.8%, 15.4% and 98.2%, 98.2%, 96.0%, 91.0% for NF90-30 bar + BW30-35 bar, NF90-30 bar + BW30-25 bar, NF270-30 bar + BW30-35 bar and single BW30-35 bar, respectively.The qualities of the product waters of integrated systems (NF+BWRO) and the single BWRO system were also investigated. Boron rejection was fairly well with average boronrejections of 59.3% and 60.2% by NF90-30 bar + BW30-25 bar and NF90-30 bar + BW30-35 bar combinations, respectively while single BW30-35 bar gave an average rejection of49.6%. The results obtained showed that the quality of product water obtained using single BWRO did not comply with the irrigation standards, while the integrated systems providedtotal compliance to irrigation standards with the exception of boron.

Sustainable Groundwater Exploitation Aiming at the Reduction of Water Vulnerability in the Brazilian Semi-Arid Region

Semi-arid regions have historically suffered from low water availability. In addition, the increasing frequency and intensity of extreme weather events credited to global climate change has made it increasingly clear that among the challenges faced by society water resource management is extremely necessary. In this context, desalination based on renewable energy resources integrated with production systems that make use of the waste resulting from this process becomes a socio-environmentally indicated alternative to expand existing supply strategies and sustainable water use in isolated locations, and/or areas distant from large urban centers, thus addressing local potential and reducing environmental impacts. This study assesses the use of Photovoltaic Solar Power Plants (PSPPs), as well as of residues generated in a Brackish Water Reverse Osmosis System (BWRO), in productive units linked to fish and family farming. This is as an alternative way to reduce water vulnerability in the Brazilian semi-arid area (BS), adhering to climate change adaptation measures in the light of Brazilian public policies through the Freshwater Program (Programa Água Doce—PAD), which aims to promote access to good quality water to approximately 500 thousand people in the Brazilian semi-arid region.

Renewable energy powered membrane technology: Impact of solar irradiance fluctuations on performance of a brackish water reverse osmosis system

Abstract Fluctuations in solar irradiance were varied in frequency and magnitude to investigate the performance of a directly-connected solar energy powered reverse osmosis (RO) membrane system. Typically, the system produced acceptable quality water with constant solar irradiances ranging from 400 to 1200 W m −2 . Low average motor powers were encountered during fluctuations, however, in many cases, good performance was still realised, even at solar irradiance values that were equivalent to −2 . This counter-intuitive result arises from the effect of averaging the motor power, with periods of high solar irradiance compensating for the under-performance at times when the system was off. Overall, even though the permeate flux was often low when operating under fluctuating conditions, the RO system continued to deliver satisfactory quality water and at a low specific energy consumption (SEC). Temporal studies revealed that a disruption of the concentration polarisation layer occurs via a naturally induced backwash for steps in the solar irradiance as low as 100 W m −2 . This suggests that a renewable energy powered RO filtration system could benefit from being operated from a fluctuating energy source. Furthermore, the operating conditions during the first couple of minutes after a system shutdown event is shown to be very important, with: (i) shorter off-periods resulting in good performance being achieved quicker, and (ii) short-term power availability dramatically improving system performance. These findings indicate that a renewable energy powered RO system can operate well from a fluctuating energy source, in particular when additional power – for example, via supercapacitor energy buffering – is available to boost the system after a shut-down period.

Management of BWRO systems using long-term monitoring of feed water quality to avoid future membrane process failure

AbstractPumping of wells from aquifers that are used to supply brackish-water reverse osmosis (BWRO) treatment systems commonly causes increases of water salinity in time. Some key aspects of assuring operational security are the magnitude of the water quality changes to assure that treatment can continue without failure of the process, reduction in installed capacity, or the necessity to modify the process by increasing the operational pressure and changing the membranes. An example of a BWRO system that uses a leaky aquifer system as a source of feed water located in Florida shows that careful monitoring of the well water quality and individual well pumping rates over a 10-year operating period can be used to assess the projected long-term changes in water quality with regard to the treatment facility design. The total dissolved solids concentration of the wellfield began with an average TDS of 2,461 mg/L which changed over 10 years to an average of 2,855 mg/L. The variation in time is linear and the pr...

High recovery rate NF–FO–RO hybrid system for inland brackish water treatment

Brackish water desalination is a common method for fresh water supply in arid areas. Concentrated brine is the major waste stream generated from the desalination process. The current study proposes a multi-stage Nanofiltration (NF)–Forward Osmosis (FO)–Brackish Water Reverse Osmosis (BWRO) system to increase the recovery rate of brackish water. The simulation results showed that the NF–FO–BWRO system was able to achieve >90% recovery rate for a number of feed salinities varied from 1 to 2.4g/L. High permeability NF membrane was used in the first stage to produce the first permeate flow at relatively low power consumption. Concentrated brine from the NF was fed to an FO membrane for power for additional fresh water extraction before disposal. 0.25–0.5M NaCl was used as the draw solution in the FO membrane. The results showed that system recovery rate increased with increasing the concentration of the draw solution. NF process was responsible of 75% of the total recovery rate while BWRO process contribution was up to 20%. Almost 80% of the total power consumption for desalination was due to the BWRO process. NF and FO processes accounted for the rest 20% power consumption. The BWRO system also required 2 to 3 times more membranes than FO and NF processes. NF–FO–BWRO is flexible and can generate different proportions of permeate flows through controlling the recovery rates of each component.

Comparison of Configurations for High-Recovery Inland Desalination Systems

Desalination of brackish groundwater (BW) is an effective approach to augment water supply, especially for inland regions that are far from seawater resources. Brackish water reverse osmosis (BWRO) desalination is still subject to intensive energy consumption compared to the theoretical minimum energy demand. Here, we review some of the BWRO plants with various system arrangements. We look at how to minimize energy demands, as these contribute considerably to the cost of desalinated water. Different configurations of BWRO system have been compared from the view point of normalized specific energy consumption (SEC). Analysis is made at theoretical limits. The SEC reduction of BWRO can be achieved by (i) increasing number of stages, (ii) using an energy recovery device (ERD), or (iii) operating the BWRO in batch mode or closed circuit mode. Application of more stages not only reduces SEC but also improves water recovery. However, this improvement is less pronounced when the number of stages exceeds four. Alternatively and more favourably, the BWRO system can be operated in Closed Circuit Desalination (CCD) mode and gives a comparative SEC to that of the 3-stage system with a recovery ratio of 80%. A further reduction of about 30% in SEC can be achieved through batch-RO operation. Moreover, the costly ERDs and booster pumps are avoided with both CCD and batch-RO, thus furthering the effectiveness of lowering the costs of these innovative approaches.

Closed circuit desalination series No 7: retrofit design for improved performance of conventional BWRO system

Abstract Improved performance of conventional brackish water reverse osmosis (BWRO) technology is achieved by the integration with the newly conceived closed circuit desalination (CCD) technology of low energy consumption without need of energy recovery, low scaling and fouling characteristics, high recovery irrespective of number of elements per modules, wide range operational flux, and flexible control of membranes and modules performance in compliance with manufacturers’ specifications. The present article describes the application of a retrofit system for 88.5% desalination of a feed source (6,500 μS/cm) whereby permeate (324 μS/cm) was obtained with reverse osmosis energy consumption of 0.555 kWh/m3 and an overall energy consumption of 0.609 kWh/m3—these results were unattainable by a full-scale conventional BWRO desalination complex which operated adjacent to the retrofit unit with the same feed source. The retrofit unit under review utilizes the pressurized brine flow from a conventional BWRO pass ...

Design aspects of small-scale photovoltaic brackish water reverse osmosis (PV-BWRO) system

Clean drinking water is essential for survival and good health. Reverse osmosis is a very effective way to produce clean drinking water. Designing small scale photovoltaic powered brackish water reverse osmosis system (PV-BWRO) requires feed water characterization, proper pre-treatment setup, module design configuration, energy consumption evaluation and reject water management. Feed water characterization is done for optimum RO module arrangements and pre-treatment design to prevent fouling and scaling. Success of small scale PV-BWRO system designation depends on ability to minimize cost of water produced. Among all the parameters effecting cost, energy is the most influential. Energy consumption is reduced by including energy recovery device (ERD) in the system. It can be further reduced by including battery for stable supply of energy enabling the pumps to operate at optimum level. Problem with battery is energy loss during charging/discharging and high cost of maintenance and replacing. Instead of storing energy, another option is to store produced fresh water in storage tank. The capacity of the tank is determined based on average consumption of water by the population at the location of the system build. Reject water from RO system need to be managed properly. Improper disposal will cause contamination and disturb ecosystem. Powering RO systems with PV panels have a lot of advantages which includes maintenance free, easy installation and last up to 25 y.

Defluoridation of brackish northern Sahara groundwater — Activity product calculations in order to optimize pretreatment before reverse osmosis

High fluoride concentrations in water cause problem in terms of public health. Owing to its efficiency, reverse osmosis (RO) was considered for water defluoridation. However, this technique is not selective. The recovery by means of brackish water RO system is therefore limited by salt precipitation. A computer calculation program was developed to determine the activity products a Ca 2 + . a CO 3 2 − , a Ca 2 + . a SO 4 2 − and a Ca 2 + . a F − 2 by taking into account the influence of all present free and associated species (ion pairs). These activity products are then compared with the solubility product of calcite (CaCO 3), gypsum (CaSO 4,2H 2O) and fluorite (CaF 2). The results allowed a theoretical estimation of the brackish water RO recovery which can be achieved without scaling. From the calco-carbonic equilibrium curve, the Legrand–Poirier diagram allowed to optimize the amount of softening substance (sodium carbonate and soda mixtures) to be added to obtain water which can be subsequently concentrated by reverse osmosis. An experimental softening pretreatment of Algerian brackish water was considered according to the optimal calculated softening amount of 15 mmol L − 1 of sodium, added in the form of sodium carbonate and soda (16%). The pretreatment allowed not only an almost total removal of the calcium but also a partial elimination of magnesium and fluoride.

Analysis of desalination alternates for phosphoric acid plant in Tunisia

A sulfuric acid/phosphoric acid production facility being constructed in Tunisia will require an average of 485 m 3/hr of process and potable water. There is insufficient fresh water available and desalination of brackish ground water or sea water is required. Three basic cases were studied: thermal sea water desalination using heat recovery; reverse osmosis desalination of brackish water and; part reverse osmosis and part thermal sea water desalination. Total heat rejected through acid coolers from the two 1750 tonne/day sulfuric acid lines is 58×10 6 KCal/hr. This is at a high enough temperature level to operate either an MSF type plant or MED type plant. A 10 stage MSF plant and a 3 effect MED plant with a flash stage were designed. Heat recovery is accomplished by plate type heat exchangers. The brackish water reverse osmosis system will produce water of three different qualities using two product stages. Raw water supply has 3434 ppm chlorides and some of this water is blended with the first stage product water for the required process water. In the combined systems, process water and potable water are produced in th RO system while high purity boiler make-up water is produced in thermal evaporators using the brine reject from the RO plant as feed. Three types of evaporators are examined: heat recovery, thermal compression and steam. Capital and operating cost estimates are given for all six cases. The RO system is lowest in capital costs but the MED system with heat recovery is lowest in operating costs. The system is also lowest in total present worth costs. The high costs of electricity and water wells at this site combined to make sea water desalination using heat recovery the most economical solution. A subsequent analysis using lower cost, internally generated electricity from waste heat resulted in lower present worth costs for all systems and the all brackish water RO system was decided upon.