WO2025198597A1

WO2025198597A1 - High recovery twin paired dual staging seawater ro membrane system configuration

Info

Publication number: WO2025198597A1
Application number: PCT/US2024/021168
Authority: WO
Inventors: Mohamad Amin SAAD
Original assignee: Masar Technologies Inc; Saad Margaret Rose
Current assignee: Masar Technologies Inc; Saad Margaret Rose
Priority date: 2024-03-22
Filing date: 2024-03-22
Publication date: 2025-09-25
Anticipated expiration: 2026-09-22

Abstract

A novel two-staged, high recovery seawater Reverse Osmosis membrane desalination system configuration via direct twin-pairing of each two membrane pressure vessels in the system with the brine flow outlet of the first vessels, acting as the first stage, is directly connected to the feed flow inlet of the second vessel, acting as the second stage, eliminating the need for a large header piping connecting the two stages, or the need for a booster pump between the two stages, as is the case with all multi-staged system designs. The advantages of this configuration include maximizing the overall system productivity by 10-22% and recovery rates of 54%-61%, as compared to an average of 45% currently achieved by most, operating single-staged seawater RO membrane desalination plants. It also minimizes the plants' energy by 21-26%, chemical consumption rates, and total costs of producing desalinated water by 18-26%, and improves their environmental friendliness and acceptance.

Description

High Recovery Twin Paired Dual Staging Seawater RO Membrane System Configuration

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

BACKGROUND OFTHE INVENTION

The vast majority of seawater RO membrane desalination plants around the world today have traditionally been designed and operated at limited product recovery ratios of 45%-50% in a single brine-staged membrane system configuration (Figure 1 - Prior Art 1). The technology has come a long way since the advent of the technology some 5 decades ago, when most plants were designed and operated at 25-30% in product recovery ratio. This is due to the high salinity of treated raw seawater and the solubility limitations of major salt constituents, such as calcium carbonate and calcium sulfate, which can lead to heavy chemical scaling of the RO membranes on the brine side if concentrated beyond a factor of 1.2-2. OX, which is inversely proportional to the product recovery ratio. This is in addition to the limitations on commercially-available membrane integrity, useful life and maximum allowable operating conditions, such as the feed pressure, now up to 82 bar. This is reflected in major limitations on achieving the maximum achievable productivity, minimum specific energy consumption, minimum production of brine, to be disposed of, recycled back to the ocean or subject to further treatment. Consequently, significant limitations exist on achieving the lowest possible cost of producing desalinated water. Prior attempts to date (Figure 5 - Prior Art 3) to add a second stage to seawater RO systems have always required the addition of an expensive and energy-intensive high-pressure booster pump with severe limitations on the second-stage recovery rate, and in some cases, the inclusion of special ultra-high pressure membranes that can operate at pressures of up tolOO bar, all with little net value in overall system productivity at a much higher specific energy consumption due to the pressure losses in the second-stage header piping and auxiliaries, and consequently, higher capital and operation & maintenance costs, adding up to higher energy consumption rates and total costs of producing desalinated water ($/m³ produced). BRIEF SUMMARY OF THE INVENTION

This invention is designed to take the technology to the next level by substantially increasing the average recovery rates of currently operating and future seawater RO systems to much higher levels, in the neighborhood of 55-60% ((Figures 3, 4 - Twin-Paired 1, 2), or higher, not possible now with the industry-standard single-stage configuration, via an innovative dual-stage configuration, while still meeting the same existing confines of operating pressures and product fluxes, and without the addition of a second-stage booster pump and auxiliaries, or risking excessive membrane scaling or fouling, or worse, membrane premature failure. This is accomplished by introducing a 1:1 membrane configuration, whereby each two membrane pressure vessels are individually and directly twin-paired to operate as first and second stage, respectively. This eliminates significant pressure losses resulting from using a second-stage booster pump and header piping typically required in multi-stage system configurations (Figure 5 - Prior Art 3) to achieve comparable overall recovery rates. It also eliminates the need to use ultra-high pressure, energy-intensive and very costly specialty membranes, often required in a typical second stage

This invention allows increasing the productivity rates of these plant by up to 22%, or possibly higher, lowering the volume of the required treated seawater feed flow, and/or reducing the volume of the final brine flow to produce the same plant capacity under the same water and operating conditions of existing single-stage seawater RO membrane desalination plants by up to 42.7%, while lowering the specific energy consumption rates by up to 25%, lower the capital and operating and maintenance costs, and consequently the total cost of producing desalinated water, by similar rates, while at the same time improving the overall system's hydraulic balance, membrane scaling and fouling control and environmental friendliness and acceptance of these plants.

DETAILED DESCRIPTION OF THE INVENTION

This invention addresses one of the main and critical issues in optimizing the design and operational efficiency, and consequently energy consumption and total cost effectiveness of seawater reverse osmosis membrane desalination plants. The current industry standard is to design and operate these plants at 40-45% in product recovery rate (Figure 1, Table 1), or possibly up to 50% employed by some small, experimental or pilot plants (Figure 2, Table 2), which is the ratio of the flow rate of desalinated water (i.e., permeate) to the total feed flow rate. A higher product recovery rate allows either the production of more product at the same feed flow rate, or drawing less feed to product he same amount of product, or a combination of the two options, as decided by the plant. Either or both of both options will results in lowering the energy, chemical, maintenance and other daily operating costs, in addition to maximizing the efficiency and useful life of the membranes and other plant equipment. Since energy consumption is about 90% related conclusively to the RO system's high-pressure pump operation, and since 50-75% of the plant's daily operation and maintenance costs, depending on the plant's location, site conditions and power costs, are related to energy consumption, which is directly related to the product recovery rate, any improvement in the product recovery rate will directly lead to significantly lowering the plant's daily operation and maintenance costs, which constitute 50% or more of the total costs of producing desalinated water.

This innovative configuration is designed to enable seawater RO membrane desalination plants to achieve higher recovery rates in the neighborhood of 55-60%, and potentially higher, not before possible in currently operating, single-stage seawater RO plants. This is achieved by directly and individually pairing each two pressure vessels (i.e., twin-pairing), each housing 1-8 membrane element cartridges, in such a way whereby the brine port of the first vessel, now acting as a first stage, is directly linked to the feed port of the second vessel, now acting as a second stage, to form a 1:1 dual staging configuration (Figures 3, 4, Tables 3, 4), as opposed to the industrystandard single-stage configuration employed at most, if not all, currently operating and future designed RO plants (Figure 1, Table 1). It is also different than the standard 2:1 staging configuration (Figure 5), whereby the brine ports of first-stage pressure vessels are piped to a common brine header, which, in turn, feeds all second-stage pressure vessels, typically in a 2:1 staging configuration (the number of pressure vessels in the fist stage are double the number of those in the second stage. This configuration almost always requires the addition of a high- pressure booster pump (Figure 5, Table 5) since the pressure in the brine header is not enough to affect further desalination of second-stage membranes due to large pressure losses in the header itself, as well as the booster pump and auxiliaries.

This invention allows via its 1:1 membrane system configuration further desalination of a portion of first-stage brine, without the addition of energy-intensive and high-capital booster pump to achieve a higher overall system product recovery rates of up to 60%, or potentially higher, since all potential pressure losses related to the brine header and booster pump are eliminated, providing enough net pressure driving force for further desalination of second-stage membranes are higher recovery rates of 22%, or potentially higher, as opposed to the currently achievable 45% by most, if not all of the single-stage seawater RO membrane desalination plants operating around the world (Figure 1, Table 1), or even the conceptual 2:1 staging configuration with a brine der and a booster pump designed to further desalinate the first-stage brine by a second stage operation under 12% product recovery rate.

This invention also results in better hydraulic balance and long-term stability of the entire system, as well as better control over concentration polarization, membrane fouling and/or chemical scaling development potentials via operation at currently-acceptable product flux rates and high pressures not exceeding 80 bar, which most commercial membrane elements are designed to tolerate, and more environment-friendly operation due to using less raw seawater and/or lower brine flow rates requiring less environmental handling, remediation, return to the marine life and/or disposal.

All technical design specifications listed in all tables, as referred to in all figures, as well as the summaries listed in Table 6, have been calculated as results of computer design projections using pu blicly-avai la ble DuPont de Nemour's Water Application Value Engine (WAVE^a), Computer Projection Program, version 1.81-2023, using actual average seawater conditions and operating environments available at most medium-large seawater RO plants around the world. The membrane elements used in all projections are spiral-wound, DuPont Water Solutions' model number SW30HRL-440 (8 elements in each pressure vessel).

Four cases are to made to demonstrate the benefits, ingenuity and uniqueness of the invention over the current industry-standard single (Prior Art 1) and dual staging (Prior Art 2 and 3) membrane system configurations, under typical membrane RO desalination plant seawater conditions and operating environments.

CASE 1

Figure 1, Table 1 show an industry-standard single-stage seawater RO membrane system configuration, operating at 45.1% product recovery, whereby the brine ports of all pressure vessels, each housing 1-8 membrane elements, are connected to a common brine header, which then directs the final brine to an Energy Recovery Device (ERD) to regain the outlet pressure and transmit it back to the High-Pressure Pump (HPP) before the final depressurized brine is sent to a nearby wastewater treatment facility, further treated on site, or returned to the ocean. As contrasted by the invention's 1:1 dual-staging configuration, operating at a first-stage product recovery rate of 45.1% (Twin-Paired 1), the single-stage configuration (Prior Art 1) is limited to 45% product recovery rate due to the high concentration of the produced brine, making it very difficult, if not impossible, and uneconomical to further desalinate it further due to the high salinity of produced brine. ON the other hand, the invention's 1:1 dual-staging configuration (Twin-Paired 1) is capable of adding a second stage to further desalinate the first-stage brine at a recovery rate of 22.7% (Figure 3, Table 3) to achieve an overall system recovery rate of 54.3%, or possibly higher, increasing the overall system productivity by 21%, while lowering the specific energy consumption rate by as much as 25.3%, and lowering the final brine flow rate to be sent to a wastewater treatment facility, sent back to the ocean or further treated by 42.7% (Table 6), significantly lowering the total cost of producing desalinated water by similar rates.

CASE 2

Figure 2, Table 2 show conceptual, industrial/academic research or pilot plant shows an industrystandard single-stage seawater RO membrane system configuration, operating at 50.1% product recovery, whereby the brine ports of all pressure vessels, each housing 1-8 membrane elements, are connected to a common brine header, which then directs the produced brine to a feed common header feeding the second stage for further desalination. The final brine produced by the second-stage membranes is directed to an Energy Recovery Device (ERD) to regain the outlet pressure and transmit it back to the low-pressure pretreated feed, which is then connected to the High-Pressure Pump (HPP), before the final brine is depressurized and sent to a nearby wastewater treatment facility, further treated on site, or returned to the ocean. A dual-stage configuration like this is limited to 55% product recovery rate due to the high concentration of the produced brine, making it very difficult and uneconomical to further desalinate without requiring the addition of a booster pump to the second-stage feed, and possibly utilizing highly energy-intensive and very costly ultra-high-pressure membranes, significantly adding to the energy consumption rate and total cost of producing desalinated water. As contrasted by the 2:1 dual staging configuration (Prior Art 2), the invention's 1:1 dual-staging configuration (Twin- Paired 2), operating at a first-stage product recovery rate of 50.1%, is capable of adding a second stage to further desalinate the first-stage brine at a recovery rate of 23.4% (Figure 3, Table 3), for an overall system product recovery rate of 61.2%, which 22% higher than single-stage configuration (Prior Art 2), or possibly higher, increasing the overall system productivity by 22%, while lowering the specific energy consumption rate by as much as 21%, and lowering the final brine flow rate to be sent to a wastewater treatment facility, sent back to the ocean or further treated by 19.5% (Table 6), significantly lowering the total cost of producing desalinated water by similar rates.

CASE 3

Figure 3, Table 3 show the invention's unique 1:1 dual-stage seawater RO membrane system configuration, designed at first-stage product recovery rate of 50.1% (Twin-Paired 2, whereby the brine ports of each pressure vessel, housing 1-8 membrane elements and constituting the first stage in the system, is individually and directly connected to the feed port of the next pressure vessel, housing 1-8 membrane elements and constituting the second stage. As contrasted by the single-staging configuration, operating at a first-stage product recovery rate of 45.1% (Prior Art 1), the invention's 1:1 dual-staging configuration (Twin-Paired 1) is capable of adding a second stage to further desalinate the first-stage brine at a recovery rate of 23.4% (Figure 3, Table 3), for an overall system product recovery rate of 61.2%, 36% higher than single-stage configuration (Prior Art 1), or possibly higher, increasing the overall system productivity by 10%, while lowering the specific energy consumption rate by as much as 26.1%, and lowering the final brine flow rate to be sent to a wastewater treatment facility, sent back to the ocean or further treated by 38.5% (Table 6), significantly lowering the total cost of producing desalinated water by similar rates.

CASE 4

Figure 4, Table 4 show the invention's unique 1:1 dual-stage seawater RO membrane system configuration, designed at first-stage product recovery rate of 50.1%, same as currently may be achieved by a conceptual, industrial research or pilot plant 2:l-stage configuration (Prior Art 2), whereby the brine ports of each pressure vessels, housing 1-8 membrane elements and constituting a first stage in the system, is individually and directly connected to the feed port of the next pressure vessel, housing 1-8 membrane elements and constituting a second stage (Twin- Paired 2), not connected to a common brine header to feed the second-stage membranes, and not requiring a second-stage booster pump and auxiliaries (Prior Art 3 - Figure 5, Table 5), thus eliminating significant pressure losses and providing higher net pressure driving force for further, more efficient desalination of second-stage brine. The produced brine from the second-stage membranes is then directed to a common brine header, which, in turn, directs the final brine to an Energy Recovery Device (ERD) to regain the outlet brine's pressure and transmit it back to the low-pressure pretreated feed, which is then connected to the High-Pressure Pump (HPP), before the final brine is depressurized and sent to a nearby wastewater treatment facility, further treated on site, or returned to the ocean. As contrasted by industry-standard membrane configuration (Prior Art 3 - Figure 5, Table 5), the invention's 1:1 dual-stage configurations (Twin- Paired 2) are capable of achieving higher product recovery rates up 61.3%, which is 10% higher than 2:l-stage configuration (Prior Art 3 - Figure 5, Table 5), and possibly higher, higher plant productivity rates of 18%, and lower specific energy consumption rate by 18%, without the need for a second-stage booster pump to power the second-stage feed, and possibly the need to utilize highly energy-intensive and very costly ultra-high-pressure membranes. This results in achieving a corresponding reduction in the total cost of producing desalinated water via seawater membrane technology applications that is not possible with either 2:1 dual-stage configuration (Prior Art 3 - Figure 5, Table 5), single-stage configuration at 50.1% product recovery rate (Prior Art 2 - Figure 2, Table 2), or single-stage configuration at 45.1% product recovery rate (Prior Art 1 - Figure 1, Table 1).

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Figure 1) Single-Stage Seawater RO At 45.1% Product Recovery Process Schematic - Prior Art 1

This figure shows an industry-standard process design layout of a single-stage seawater RO membrane system, as applied to the vast majority of RO membrane desalination plants around the world operating at 45.1% product recovery rate. The figure's notations and technical specifications are summarized in Table 1.

Figure 2) Single-Stage Seawater RO At 50.1% Product Recovery Process Schematic - Prior Art 2

This figure shows an industry-standard process design layout of a single-stage seawater RO membrane system, as applied to the vast majority of RO membrane desalination plants around the world operating at 50.1% product recovery rate. The figure's notations and technical specifications are summarized in Table 2.

Figure 3) Dual-Stage Seawater RO At 54.3% High Product Recovery Process Schematic Twin- Paired 1

This figure shows the invention's process design layout of a 1:1 dual-stage seawater RO membrane system, to be applied to currently operating and future designed seawater RO membrane desalination plants around the world at operating with first-stage product recovery rate of 45.1% and second-stage product recovery rate of 22.7% for an overall system product recovery rate of 54.3%. The figure's notations and technical specifications are summarized in Table 3.

Figure 4) Dual-Stage Seawater RO At 61.2% High Product Recovery Process Schematic - Twin- Paired 2

This figure shows the invention's process design layout of a 1:1 dual-stage seawater RO membrane system, to be applied to currently operating and future designed seawater RO membrane desalination plants around the world at operating with first-stage product recovery rate of 50.1% and second-stage product recovery rate of 23.4% for an overall system product recovery rate of 61.2%. The figure's notations and technical specifications are summarized in Table 4.

Figure 5) Two-Stage Seawater RO At 50.1% Product Recovery Process Schematic - Prior Art 3

This figure shows a conceptual process design layout of a 2:l-staged seawater RO membrane system, as applied to experimental, applied research or pilot RO membrane desalination systems with first-stage product recovery rate of 49.2% and second-stage product recovery rate of 11.9% for an overall system product recovery rate of 55.2%. The figure's notations and technical specifications are summarized in Table 5.

PRIOR ART PUBLISHED PATENTS LIST

1. PRIOR ART PATENT1-US6187200 Bl

2. PRIOR ART PATENT2-US8679347 B2

3. PRIOR ART PATENT3-US10603635 B2

4. PRIOR ART PATENT4-US11203535

5. PRIOR ART PATENT5-US10052589

6. PRIOR ART PATENT6-US20170080389 Al

APPLICANT NAME

Mohamad Amin Saad

APPLICANT CITIZENSHIP

Unted States

APPLICANT RESIDENCE

Unted States

TITLE OF INVENTION

TABLES

TABLE 1 - Single-Staged Seawater RO Membrane System Projected Technical Data at 45.1% Product Recovery

TABLE 2 - Single-Staged Seawater RO Membrane System Projected Technical Data at 50.1% Product Recovery

TABLE 3 - Twin-Paired Dual Stage Seawater RO Membrane System Projected Technical Data at 54.3% Product Recovery

TABLE 4 - Twin-Paired Dual Stage Seawater RO Membrane System Projected Technical Data at 61.2% Product Recovery

TABLE 5- 2:1-Staged Seawater RO Membrane System Projected Technical Data at 55.2% Product Recovery

TABLE 6-AComparative Summary of All of the Invention's 1:1 Twin-Paired's to All Prior Arts' Configurations

Claims

1. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves higher overall system recoveries of 54.3% (Twin-Paired 1), and possibly higher, up from 45.1%, currently possible by existing or currently designed single-staged seawater RO membrane desalination plants (Prior Art 1), under the same water and operating conditions.

2. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves higher overall system recoveries of 61.2% (Twin-Paired 2), and possibly higher, up from 50.1%, currently possible by existing or currently designed 2:1 dual-staged seawater RO membrane desalination plants, operating at the same first-stage product recovery rate of 50.1% (Prior Art 2), without the addition of a second stage booster pump and auxiliaries, and/oraddition of ultra-high-pressure specialty membranes and auxiliaries, under the same water and operating conditions.

3. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves higher overall system recoveries of 61.2% (Twin-Paired 2), and possibly higher, up from 45.1%, currently possible by existing or currently designed single-staged seawater RO membrane desalination plants, operating at the same first-stage product recovery rate of 45.1% (Prior Art 1), underthe same water and operating conditions.

4. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves higher overall system recoveries of 61.2% (Twin-Paired 2), and possibly higher, up from 55.2%, currently possible by existing or currently designed 2:1 dual-staged seawater RO membrane desalination plants, operating at the same first-stage product recovery rate of 50.1% (Prior Art 2), without the addition of a second stage booster pump and auxiliaries, and/oraddition of ultra-high-pressure specialty membranes and auxiliaries, under the same water and operating conditions.

5. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves higher overall system productivity by 21% (Twin-Paired 1), and possibly higher, up from 45.1%, currently possible by existing or currently designed single-staged seawater RO membrane desalination plants (Prior Art 1), underthe same water and operating conditions.

6. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves higher overall system productivity by 22% (Twin-Paired 2), and possibly higher, up from 50.1%, currently possible by existing or currently designed 2:1 dual-staged seawater RO membrane desalination plants, operating at the same first-stage product recovery rate of 50.1% (Prior Art 2), without the addition of a second stage booster pump and auxiliaries, and/oraddition of ultra-high-pressure specialty membranes and auxiliaries, under the same water and operating conditions.

7. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves higher overall system productivity by 10% (Twin-Paired 2), and possibly higher, up from 45.1%, currently possible by existing or currently designed single-staged seawater RO membrane desalination plants, operating at the same first-stage product recovery rate of 45.1% (Prior Art 1), underthe same water and operating conditions.

8. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves higher overall system productivity by 18% (Twin-Paired 2), and possibly higher, up from 55.2%, currently possible by existing or currently designed 2:1 dual-staged seawater RO membrane desalination plants, operating at the same first-stage product recovery rate of 50.1% (Prior Art 2), without the addition of a second stage booster pump and auxiliaries, and/oraddition of ultra-high-pressure specialty membranes and auxiliaries, under the same water and operating conditions.

9. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower energy consumption rate by 25.3% (Twin-Paired 1), as compared to what is currently possible by existing or currently designed single-staged seawater RO membrane desalination plants (Prior Art 1), without the addition of a second stage booster pump and auxiliaries, and/or addition of ultra-high- pressure specialty membranes and auxiliaries, under the same water and operating conditions.

10. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower energy consumption rate by 21% (Twin-Paired 2), as compared to what is currently possible by existing or currently designed 2:1 dual-staged seawater RO membrane desalination plants (Prior Art 2), without the addition of a second stage booster pump and auxiliaries, and/oraddition of ultra-high-pressure specialty membranes and auxiliaries, under the same water and operating conditions.

11. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower energy consumption rate by 26.1% (Twin-Paired 2), as compared to what is currently possible by existing or currently designed single-staged seawater RO membrane desalination plants (Prior Art 1), without the addition of a second stage booster pump and auxiliaries, and/or addition of ultra-high- pressure specialty membranes and auxiliaries, under the same water and operating conditions.

12. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower energy consumption rate by 18% (Twin-Paired 2), as compared to what is currently possible by existing or designed 2:1 dual-staged seawater RO membrane desalination plants (Prior Art 2), without the addition of a second stage booster pump and auxiliaries, and/oraddition of ultra-high-pressure specialty membranes and auxiliaries, underthe same water and operating conditions.

13. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower capital costs of using raw and treated feed seawater flow rates than currently possible by existing single-stage seawater RO membrane desalination plants membrane desalination plants, underthe same water and operating conditions, due to lower sizing of feed intake, pretreatment filtration, chemical dosing, pump and piping systems required.

14. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower operating and maintenance costs of using raw and treated feed seawater flow rates than currently possible by existing single-stage seawater RO membrane desalination plants membrane desalination plants by a minimum of 20%, and possibly more, under the same water and operating conditions, due to smaller feed intake, pretreatment filtration, chemical dosing, pump and piping systems required.

15. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower total costs of producing water due to lower capital, operating and maintenance costs and lower energy consumptions rates required by using lower raw and treated feed seawater flow rates than currently possible by existing single-stage seawater RO membrane desalination plants membrane desalination plants by a minimum of 20%, and possibly more, under the same water and operating conditions, due to smaller feed intake, pretreatment filtration, chemical dosing, pump and piping systems required.

16. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration (Twin- Paired 1) that achieves production of lower brine or reject flow rate by 42.7%, than currently possible by existing single-stage seawater RO membrane desalination plants membrane desalination plants (Prior Art

1), under the same water and operating conditions, requiring less environmental handling, remediation, further treatment, and/or disposal.

17. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration (Twin- Paired 2) that achieves production of lower brine or reject flow rate by 19.5%, than currently possible by existing 2:1 dual-stage seawater RO membrane desalination plants membrane desalination plants (Prior Art

2), under the same water and operating conditions, requiring less environmental handling, remediation, further treatment, and/or disposal.

18. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration (Twin- Paired 2) that achieves production of lower brine or reject flow rate by 38.5%, than currently possible by existing single-stage seawater RO membrane desalination plants membrane desalination plants (Prior Art 1), under the same water and operating conditions, requiring less environmental handling, remediation, further treatment, and/or disposal.

19. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower environmental impact than currently possible by existing single-stage seawater RO membrane desalination plants membrane desalination plants, due to lower production of brine streams due to the higher recoveries of two-stage, twin-paired plants, requiring less environmental handling/remediation, further treatment, return to the ocean or disposal.

20. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower operating and maintenance costs due to less production of brine or reject flow rates than currently possible by existing single-stage seawater RO membrane desalination plants membrane desalination plants by 20% at a minimum, and possibly more, under the same water and operating conditions, requiring less environmental handling, remediation, further treatment, and/or disposal.

21. A high-recovery, twin-paired, dual-staging seawater RO system membrane configuration that achieves lower total water production costs (i.e., cost of water) than currently possible by existing or currently designed multi-stage seawater RO membrane desalination plants membrane desalination plants by 20% at a minimum due to the higher productivity, lower energy consumption, lower feed intake, lower pretreatment filtration, more chemical dosing, lower operation and maintenance costs, under the same water and operating conditions of existing single-stage seawater RO membrane desalination plants membrane desalination plants.