Water treatment system and a water treatment method

Abstract

A water treatment system is provided. Water treatment system includes a feedwater conduit connect to and upstream of an RO membrane module and adapted to channel feedwater to the module to be filtered to produce permeate water and reject water stream, a permeate water conduit and a reject water conduit connected to and downstream of the module to channel the permeate water and reject water stream respectively from the module. Reject water conduit includes an restrictor valve adapted to restrict the flow of the reject water through the reject water conduit, a circulation conduit connected the reject water conduit between the module and the restrictor valve and connected to the feedwater conduit upstream of the module. Circulation conduit channels a circulation stream Circulation conduit includes a circulation pump to the circulation stream from the reject water conduit through the circulation conduit to the feedwater conduit within a pre-determined circulation pressure. Circulation pump directs and combine the circulation stream with the feedwater to form an input stream channelled into the module at an input pressure, and the reject water stream exits the module at a reject pressure, whereby the reject water stream is divided into reject water pushed through the restrictor valve and circulation stream drawn into the circulation conduit. Restrictor valve is configured to maintain the reject pressure within a pre-determined level. Circulation pump and the restrictor valve are configured to maintain a pressure drop between the input pressure and the reject pressure within a pre-determined range.

Description

Water Treatment System and A Water Treatment MethodCross-Reference to Related Applications

[0001] The present application claims the benefit of Singapore Patent Application No. 10202403758U and 10202404117Q filed on November 29, 2024, and 30 December 2024 respectively, which are incorporated by reference herein.Technical Field

[0002] The present invention relates to water treatment system and a water treatment method. Specifically, the present invention relates to a tuneable water treatment system and a method thereof.Background

[0003] Conventional reverse osmosis (RO) systems are engineered primarily for the production of high-purity permeate water and are heavily dependent on sensor feedback, automated electronic logic controllers, and external chemical dosing units to maintain operational stability and manage membrane fouling. This reliance on complex electronic infrastructure and chemical intervention increases system complexity, cost, and maintenance requirements, making such systems ill-suited for decentralized, off-grid, or low-maintenance environments. These systems are particularly vulnerable to power fluctuations, sensor drift, and software failures, which can compromise reliability in remote or resource-limited settings. Frequent intervention is required for calibration, software updates, and chemical replenishment, further elevating operational burdens and costs. When it comes to fouling management, conventional RO systems typically shut down or initiate automated cleaning cycles when permeate flux drops by as little as 10-15%, relying on hazardous chemicals for cleaning, an approach that not only increases environmental impact and operator risk but also reduces system uptime and membrane lifespan. Energy efficiency is another area of concern: these systems often operate at high pressures (150-225 psi) and, as fouling increases, their energy consumption rises sharply, sometimes exceeding 4 kWh per cubic meter of water treated.

[0004] Furthermore, conventional RO systems are designed to minimize the total dissolved solids (TDS) in the permeate, not to maximize the concentration of the reject stream. As a result, they typically produce reject water with only modest increases in TDS (e g., 200-400 ppm from a 100-ppm feed), limiting their effectiveness in applications where high reject concentration or water recovery is desired. Their recovery ratios also decline sharply with fouling, reducing overall water efficiency. The dependence on real-time monitoring, predictive diagnostics, and skilled operators for tuning and troubleshooting further adds to the operational complexity, while the need for regular software and firmware updates introduces risks of obsolescence and cybersecurity vulnerabilities. Scalability and deployment flexibility are also limited, as these systems are often centralized and not easily adapted for modular, parallel, or series operation in distributed or off-grid applications.

[0005] In summary, while conventional RO systems are effective for high-purity water production in controlled environments, they are disadvantaged by their complexity, high maintenance requirements, energy inefficiency under fouling, limited reject-side performance, and lack of suitability for decentralized, low-maintenance, or off-grid applications.

[0006] There remains a need for an RO system that can operate efficiently and reliably without reliance on electronic automation or chemical intervention, while achieving high reject-side concentration and supporting robust, low-maintenance operation.Summary

[0007] According to various embodiments, a water treatment system is provided. Water treatment system includes a feedwater conduit in fluid communication with and upstream of an RO membrane module and adapted to channel feedwater to the RO membrane module to be filtered to produce permeate water and reject water stream, a permeate water conduit and a reject water conduit in fluid communication with and downstream of the RO membrane module, such that the permeate water conduit and reject water conduit are adapted to channel the permeate water and reject water stream respectively from the RO membrane module, such that the rej ect water conduit includes an restrictor valve adapted to restrict the flow of the rej ect water through the reject water conduit, a circulation conduit in fluid communication with thefeedwater conduit and the reject water conduit, such that the circulation conduit is connected to the reject water conduit between the RO membrane module and the restrictor valve and connected to the feedwater conduit upstream of the RO membrane module, such that the circulation conduit is adapted to channel a circulation stream from the reject water conduit through the circulation conduit to the feedwater conduit, such that the circulation conduit includes a circulation pump adapted to pump the circulation stream through the circulation conduit within a pre-determined circulation pressure, such that the circulation pump is adapted to direct and combine the circulation stream with the feedwater to form an input stream channelled into the RO membrane module at an input pressure, such that the reject water stream exits the RO membrane module at a rej ect pressure, such that the rej ect water stream is divided into reject water pushed through the restrictor valve and circulation stream drawn into the circulation conduit, such that the restrictor valve is configured to maintain the reject pressure within a pre-determined level, such that the circulation pump and the restrictor valve are configured to maintain a pressure drop between the input pressure and the rej ect pressure within a pre-determined range.

[0008] According to various embodiments, the feedwater flows through the feedwater conduit at a feedwater flow rate, the circulation stream flows through the circulation conduit at a circulation flow rate, and the reject water flows through the reject conduit at a reject water flow rate, such that the circulation flow rate is controlled by the circulation pump and / or the restrictor valve and is independent from the feedwater flow rate and the reject water flow rate

[0009] According to various embodiments, the circulation flow rate may be varied to vary the feedwater flow rate.

[0010] According to various embodiments, the restrictor valve may be adjusted to enable a high-velocity input stream to flush a membrane of the RO membrane module to dislodge fouling material on the membrane.

[0011] According to various embodiments, the RO membrane module may be operable within a pressure range of 0.3 MPa to 1.0 MPa and has pore sizes between 0.08 and 0.12 nanometres.

[0012] According to various embodiments, the system may further include a one-way valve along the feedwater conduit, such that the one-way valve is adapted to prevent reverse flow of the feedwater.

[0013] According to various embodiments, the system may further include an ultrafiltration (UF) unit in fluid communication with the feedwater conduit, such that the UF unit is adapted to pre-filter the feedwater before entering the RO membrane module.

[0014] According to various embodiments, the system may further include a nanofiltration (NF) unit in fluid communication with the reject water conduit, such that the NF unit is adapted to process the reject water exiting the RO membrane module.

[0015] According to various embodiments, the pre-determined circulation pressure head may be up to 15 psi.

[0016] According to various embodiments, the pressure drop is maintained when permeate flux loss in the RO membrane module due to membrane fowling progresses beyond 15% and up to 80%.

[0017] According to various embodiments, a water treatment method is provided. Water treatment method includes channelling a feedwater to a RO membrane module to be filtered to produce permeate water and reject water stream, channelling the permeate water and reject water stream respectively from the RO membrane module, restricting the flow of reject water through the reject water conduit via a restrictor valve, channelling a circulation stream from the reject water conduit through a circulation conduit to the feedwater conduit and directing the circulation stream to combine with the feedwater to form an input stream, channelling the input stream to the RO membrane module at an input pressure, such that the reject water stream exits the RO membrane module at a reject pressure, such that the reject water stream is divided into reject water pushed through the restrictor valve and circulation stream drawn into the circulation conduit, such that the reject pressure is maintained within a pre-determined level by the restrictor valve, such that the circulation conduit includes a circulation pump adapted to pump the circulation stream through the circulation conduit within a pre-determined circulationpressure, maintaining a pressure drop between the input pressure and the reject pressure within a pre-determined range by the circulation pump and the restrictor valve.

[0018] According to various embodiments, the method may include channelling the feedwater stream through the feedwater conduit at a feedwater flow rate, the circulation stream through the recirculation conduit at a circulation flow rate, and the reject water flows through the reject conduit at a reject water flow rate, and controlling the circulation flow rate by the circulation pump and / or the restrictor valve, such that the circulation flow rate is independent from the feedwater flow rate and the reject water flow rate.

[0019] According to various embodiments, the method may further include varying the circulation flow rate to vary the feedwater flow rate.

[0020] According to various embodiments, the method may further include adjusting the restrictor valve to enable a high-velocity input stream to flush a membrane of the RO membrane module to dislodge fouling material on the membrane.

[0021] According to various embodiments, the method may further include preventing reverse flow of the feedwater.

[0022] According to various embodiments, the method may further include pre-filtering the feedwater using an ultrafiltration (UF) unit before entering the RO membrane module.

[0023] According to various embodiments, the method may further include processing the reject water exiting the RO membrane module using a nanofiltration (NF) unit

[0024] According to various embodiments, the pre-determined circulation pressure head is up to 15 psi.

[0025] According to various embodiments, the method comprises maintaining the pressure drop when permeate flux loss in the RO membrane module due to membrane fowling beyond 15% and up to 80%.Brief Description of Drawings

[0026] Fig. 1 shows a schematic diagram of an exemplary embodiment of the water treatment system.

[0027] Fig. 2 shows a schematic diagram of another embodiment of the system in Fig. 1.

[0028] Fig. 3 shows a schematic diagram of another embodiment of the system in Fig. 1.

[0029] Fig. 4 shows a schematic diagram of a full-scale prototype of the system.

[0030] Fig. 5 shows an empirical result obtained from the prototype testing.

[0031] Fig. 6 shows a table of parameter and data on the performance between the benchmark systems vs the system.

[0032] Fig. 7 shows a plurality of charts of the observed operational behaviour between the system and the benchmark systems.

[0033] Fig. 8 shows an exemplary water treatment method using the system.Detailed Description

[0034] Tn the following examples, reference will be made to the figures, in which identical features are designated with like numerals.

[0035] Fig. 1 shows a schematic diagram of an exemplary embodiment of the water treatment system 100.

[0036] Water treatment system 100 includes a feedwater conduit 110 in fluid communication with and upstream of an RO membrane module 120 and adapted to channel a feedwater stream to the RO membrane module 120 to be filtered to produce permeate water and reject waterstream, a permeate water conduit 130 and a reject water conduit 140 in fluid communication with and downstream of the RO membrane module 120, such that the permeate water conduit 130 and reject water conduit 140 are adapted to channel the permeate water and reject water stream respectively from the RO membrane module 120, such that the reject water conduit 140 includes a restrictor valve 142 adapted to restrict the flow of the reject water through the reject water conduit 140, a circulation conduit 150 in fluid communication with the feedwater conduit 110 and the reject water conduit 140, such that the circulation conduit 150 is connected to the reject water conduit 140 between the RO membrane module 120 and the restrictor valve 142 and connected to the feedwater conduit 110 upstream of the RO membrane module 120, such that the circulation conduit is adapted to channel a circulation stream from the reject water conduit to through the circulation conduit 150 to the feedwater conduit 1 10, such that the circulation conduit 150 includes a circulation pump 152 adapted to pump the circulation stream through the recirculation conduit 150 within a pre-determined circulation pressure, such that the circulation pump 152 is adapted to direct and combine the circulation stream with the feedwater to form an input stream channelled into the RO membrane module 120 at an input pressure, such that the reject water exits the RO membrane module 120 at a reject pressure, such that the reject water stream is divided into reject water pushed through the restrictor valve and circulation stream drawn into the circulation conduit, such that the resistor valve 142 is configured to maintain the reject pressure within a pre-determined level, such that the circulation pump 152 and the restrictor valve 142 are configured to maintain a pressure drop between the input pressure and the reject pressure within a pre-determined range. The pressure drop is maintained within the pre-determined range even as the membrane fouling progresses up to 80% permeate flux loss. The pressure drop may be maintained within the pre-determined range even when the fouling is above 10%, 15%, 20%, 30%, 40%, 50%, 60% or 70% permeate flux loss.

[0037] As shown in Fig. 1, the feedwater flows along the feedwater conduit 110 is combined with the circulation stream from the recirculation conduit 150 as the input stream before entering the RO membrane module 120 at an input pressure and at an input flow rate provided by a pressure source, e g. RO pump and circulation pump 152, to drive the input stream through the RO membrane module 120. After filtration, the permeate water exits the RO membrane module 120 via the permeate water conduit 1 0 at a permeate water flow rate and the reject water stream exits the RO membrane module 120 via the reject water conduit 140 at a rejectpressure and at a reject water stream flow rate. Reject water stream is divided into the reject water which is pushed through the restrictor valve 142 and the circulation stream which is being drawn into the circulation conduit 150 by the circulation pump 152. Reject pressure is lower than the input pressure, i.e. a pressure drops across the RO membrane module 120, due to factors like total dissolvable solids (TDS) in the feedwater stream, the circulation stream and the amount of fowling in the RO membrane module 120. At a reject pressure, the reject water flow rate is automatically reduced by the restrictor valve 142. In the event that the reject pressure increases (or drops) sharply, the restrictor valve 142 allows the reject water to be discharged at a faster (or slower) flow rate, without reliance on any moving parts or sensors or signal feedback. Circulation pump 152 draws and channels the circulation stream into the circulation conduit 150 within a pre-determined circulation pressure. Circulation pump 152 together with the restrictor valve 142 passively maintains the pressure drop to within a predetermined range, e.g. 15 psi, without reliance on any sensors or signal feedback. The predetermined range may be the maximum safe pressure drop limit for a RO membrane.

[0038] In terms of flow rate, the RO pump imparts a feedwater flow rate to the feedwater along the feedwater conduit 110. Circulation pump 152 imparts and controls the circulation flow rate of the circulation stream along the recirculation conduit 150. Both the feedwater flow rate and the circulation flow rate produce the input flow rate into the RO membrane module 120. Circulation flow rate affects the flow rate across the RO membrane module 120, whereby the flow rate across the RO membrane module 120 is dependent on the total dissolvable solids (TDS) in the input stream, the circulation stream and the amount of fowling in the RO membrane module 120. As it can be appreciated that the higher the TDS and amount of fouling, the slower the flow rate across the RO membrane module 120. Circulation flow rate of the circulation stream may be higher or lower than or equal to the input flow rate of the input stream. Depending on membrane fowling, the circulation pump 152 is configured to produce a circulation flow rate that is within the acceptable flow rate through the RO membrane module as will be explained later.

[0039] System 100 may be configured to vary the circulation flow rate to vary the feedwater flow rate. For example, the circulation flow rate of the circulation stream may be increased by the circulation pump 152 and the restrictor valve 142 and the feedwater flow rate may bepassively reduced in response to the circulation pressure from the circulation stream. As such, the circulation flow rate is independently adjustable using the mechanical components Hence, the input flow rate of the input stream along the feedwater conduit 110 entering the RO membrane module 120 may be increased due to the high circulation flow rate. Consequently, the pressure drop across the RO membrane module 120, and the pressure increase from the circulation pump 152 are passively balanced to stabilise the input pressure. In this way, the system 100 is able to work in a steady-state operation and is balanced. As shown, the circulation flow rate of the circulation stream is independent from the feedwater flow rate of the feedwater. An important objective of this circulation stream is to add-on to the flow rate of the feedwater, at times, even cannibalising on the feedwater flow rate, to achieve a higher combined input flow rate into the RO membrane, even near the full capacity of the RO membrane, while constraining the circulation pressure generated by the circulation pump, to stabilise the pressure drop across the membrane, and maintain stable system operation, despite its progressive fouling status, whereby the fouling status may even reach as high as 80% flux loss and above one of the percentages mentioned earlier.

[0040] Fig. 8 shows an exemplary water treatment method 800 using the system 100. Method 800 includes channelling a feedwater to a RO membrane module 120 to be filtered to produce permeate water and reject water stream in Step 810, channelling the permeate water and reject water stream respectively from the RO membrane module 120 in Step 820, restricting the flow of reject water through the reject water conduit 140 via an restrictor valve 142 in Step 830, channelling the circulation stream from the reject water conduit 140 through the circulation conduit 150 to the feedwater conduit and directing the circulation stream to combine with the feedwater to form an input stream in Step 840, channelling the input stream to the RO membrane module at an input pressure, such that the reject water stream exits the RO membrane module at a reject pressure, such that the reject water stream is divided into reject water pushed through the restrictor valve and circulation stream drawn into the circulation conduit, such that the reject pressure is maintained within a pre-determined level by the restrictor valve, such that the circulation conduit 150 includes a circulation pump 152 adapted to pump the circulation stream through the circulation conduit 150 within a pre-determined circulation pressure in Step 850, maintaining a pressure drop between the input pressure and the reject pressure within a pre-determined range by the circulation pump 152 and the restrictorvalve 142 in Step 860, without reliance or feedback from mechanical or electronic pressure sensors or flow rate sensors or water quality sensors.Pump

[0041] Circulation pump 152 may be a low-head pump configured to operate within a predetermined range, e g. within the membrane's maximum tolerable pressure drop (roughly 15 psi at the original feed flow rate) at a flow rate corresponding to the original designed feed water capacity of the membrane module 120 so that it does not increase the pressure of the circulation stream to beyond the maximum safe pressure drop limit for a standard RO membrane, This creates a passive hydraulic reference point that allows continuous operation even under severe fouling conditions. Circulation pump 150 anchors the reject pressure at the outlet of the RO membrane module 120, ensuring steady operation even as feedwater conditions or membrane fouling change.

[0042] Circulation pump 152 is operating at a substantially lower pressure than the pressure head of the feedwater exerted by the RO pump in a conventional RO membrane system, which typically is in the range of 150-250 psi. Even when the RO pump is configured to deliver less than 1 MPa pressure head during steady operation with up to 80% membrane fouling or when above 10%, 15%, 20%, 30%, 40%, 50%, 60% or 70% membrane fouling., the circulation pump 152 is still able to be configured to deliver less than 15 psi, e.g. 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 psi, pressure head during stable operation. Tn this way, the system 100 is able to prevent pressure at the membrane module 120 from exceeding its maximum rated operating pressure drop and avoiding overloading under variable input conditions, e g. pressure drop at inlet of circulation pump 152 due to pressure drop at outlet of RO membrane module due to membrane fowling. This is achieved without requiring sensor feedback or automated electronic logic control systems, while allowing manual control mechanisms.

[0043] By providing a low-head pump 152, low-pressure operation is possible and prevents silt from penetrating deep into the membrane mesh, thus reducing fouling and allowing recovery from 80% to 50%, and even up to 25%, without reliance on external chemicals. If a higher-pressure pump is used, it would push excessive mixed feedwater into the RO membrane module 120, destabilising the system 100 and necessitating sensor feedback-based automaticelectronic controls to prevent overloading. Hence, a stable and self-limiting hydraulic reference point that passively anchors the pressure dynamics of the system 100 is created so that the system 100 prevents over-circulation, stabilises flow rates, and removes the need for active pressure regulation or automated electronic control for purge management. This shifts the recirculation of the reject water flow’s purpose from performance enhancement to protecting membrane integrity, especially during fouling. The circulation flow rate may be set at a steady value ranging from 0% to 500% of the variable input stream flow rate of the input stream, provided that the operating conditions of the system 100 are maintained at a steady-state flow and membrane pressure within rated limits, such that the circulation pump 152 establishes a passive upper limit, i.e. 15 psi, for the pressure drop across the membrane, stabilising the system hydraulics and eliminating the need for active control At a circulation flow rate that is substantially higher, e.g. from 300% to 500%, of the variable feedwater flow rate of the feedwater, the system 100 is able to physically dislodge any fouling material from the membrane. System 100 may be configured to temporarily increase the pump speed to generate a circulation flow rate spike to flush the RO membrane module 120. The cleaning is passive as the system 100 continues to filter the input stream while the cleaning is in progress. The pump sizing creates a passive hydraulic reference point for system stability, enabling circulation of circulation stream without the need for active pressure regulation. A steady-state flow is achieved when the flows and pressures of the system 100 stay stable over time, despite variations in feed water quality or membrane fouling, achieved through passive hydraulic design.

[0044] System 100 may include adjustable variable frequency drive (VFD) or speed drive coupled to the circulation pump 152 to control the hydraulic conditions along the circulation conduit 150. Depending on the requirement, the VFD is configured to adjust the pump speed for optimal circulation flow rate and circulation pressure of the circulation stream.Restrictor valve

[0045] As shown above, while the flow regulation of the circulation stream is provided by the circulation pump 152, the reject water flow rate is controlled by the restrictor valve 142. Restrictor valve 142 may include orifice plates, needle valves, etc. without moving parts, e.g. spring, to regulate the reject water stream. Restrictor valve 142 may be configured to be fullyopen, fully closed or any position in-between. When the restrictor valve 142 is set to allow a pre-determined flow rate therethrough, the reject water flow rate remains stable for a given pressure. Restrictor valve 142 may be adjusted to set an initial reject water flow rate at a nominal operating pressure and operates without any electrical sensors, springs, diaphragms or automatic moving parts. Hence, pressure balancing upstream and downstream the RO membrane module 120 is achieved without active intervention. Restrictor valve 142 may be adjusted manually or motorised, e g. by a servo motor. Restrictor valve 142 once set need not be adjusted thereafter.RO Membrane module

[0046] RO membrane module 120 may be a single-stage membrane module 120. RO membrane module 120 may be configured to operate preferably within a pressure range of 0.3 MPa to 1.0 MPa. RO membrane module 120 may utilize standard RO membranes with nominal pore sizes between 0.08 and 0.12 nanometres. Similarly, nano membranes with nominal pore size between O. lnm to lOnm may be used in the embodiments, instead of RO membranes, to achieve the same technical effect by the system 100. Single-stage RO membrane module 120 enables continuous operation and is particularly suited for low-maintenance or off-grid environments. It is also possible to use a combination of RO membrane and nano membrane.

[0047] RO membrane module 120 is protected and stabilized by the low-head circulation pump 152, specifically selected to operate at or below 15 psi at a flow rate matching the original feedwater flow rate, which establishes a passive hydraulic reference point and prevents overcirculation or membrane damage.

[0048] RO membrane module 120 is able to support passive cleaning modes, including manual high-velocity flushing and in-situ cleaning using ionised water, which prolong membrane lifespan and reduce maintenance needs.One-way Valve

[0049] Fig. 3 shows a schematic diagram of another embodiment of the system 100 in Fig. 1. System 300 may include a one-way valve 312 upstream of the RO membrane module 320 alongthe feedwater conduit 310, such that the one-way valve 312 is adapted to prevent reverse flow of the feedwater.

[0050] The one-way valve 312 may be integrated to prevent reverse flow when the circulation pump 352 is inactive or when the membrane pressure drop exceeds the pump head of the feedwater, thereby protecting the membrane and maintaining flow directionality.

[0051] The one-way valve 312 and circulation pump 352 together form a passive hydraulic control mechanism, such that: (a) when the membrane pressure drop is below the circulation pump head, circulation of the circulation stream is maintained and the reject-end pressure is reduced, thereby increasing rej ect water flow’ s crossflow velocity and minimising energy loss; (b) when the membrane pressure drop exceeds the circulation pump head or when the circulation pump 352 is inactive, the one-way valve 312 prevents reverse flow, thereby avoiding bypass of the membrane module 320 thus protecting the membrane and maintaining flow directionality; and (c) this condition passively triggers a system response such as flow diversion, pressure relief, pressure-based circuit breaker, or manual intervention, such as valve 342 or variable frequency or speed control device adjustment, without requiring sensors, automated electronic control systems, or skilled operators.

[0052] One-way valve 312 and the circulation pump 352, which are passive control mechanisms, enable safe shutdown and cleaning without automation.Relief Mechanism

[0053] System 100 may include a passive over-pressure relief mechanism to protect the RO membrane module 120 and piping from transient spikes in feedwater pressure. Such a mechanism may include a spring-loaded pressure relief valve or diaphragm-based bypass installed on the feedwater conduit 110, reject water conduit 140 or the recirculation conduit 150, and is activated only under abnormal pressure conditions and resets automatically without requiring sensors or alarms.Bypass Valve

[0054] System 100 may include a bypass valve or isolation valve adapted to divert or isolate flow during maintenance, cleaning or startup of the system 100. loniser / Bipolar Electrolyser

[0055] System 100 may include an ioniser and / or bi-polar electrolyser along the feedwater conduit 110 adapted to generate ionised water or pH-adjusted cleaning solutions using electrochemical processes, used for in-situ membrane cleaning without external chemical dosing.Ultrafiltration

[0056] System 100 may include an ultrafiltration (UF) unit in fluid communication with the feedwater conduit 110, wherein the UF unit is adapted to pre-filter the feedwater before entering the RO membrane module 120 to remove suspended particles larger than 0. 1 microns.Technical Advantages

[0057] The design of the system 100 provides numerous technical advantages over conventional RO systems as will be shown below.Hydraulic Balancing

[0058] System 100 is able to operate with hydraulically balanced steady flows of water, i.e. feedwater, permeate water, circulation stream, and reject water solely through hydraulic pressure balancing.

[0059] Hydraulically balancing occurs when the flow and pressure are controlled solely by mechanical devices and pressure differences, without requiring active sensing, electronic feedback, or automated control systems. This ensures steady operation under variable fouling and feed conditions and supports passive system stability. In other words, even if the membranebecomes fouled and produces less permeate, the circulation pump 152 and restrictor valve 142 are able to maintain stable flows and pressures, preventing system shutdown.

[0060] When hydraulic pressure balancing is achieved via mechanical devices, it is possible to maintain a stable pressure of input stream within the membrane module 120's capacity, thereby reducing pressure oscillations while sustaining or enhancing permeate flux.Hydraulic Decoupling

[0061] Fig. 2 shows a schematic diagram of another embodiment of the system 100 in Fig. 1. System 100 is hydraulically configured to decouple the circulation stream 252 from the feedwater stream 214, allowing for independent adjustment of each stream, as depicted in Fig. 2. Input stream 212N may seem to include the feedwater 214 mixed with the circulation stream 252. However, it is in fact two streams flowing “together” into the RO membrane module 120. After filtration, the input stream 12 is filtered by the RO membrane module 120 into permeate water 232 and the reject water stream 212R, which as mentioned above is divided into the reject water 244 and the circulation stream 252. While the reject water 244 passes through the reject water conduit 140, it consists of the reject water stream 244 and the circulation stream 252. Hence, while it may seem that a portion of the reject water 244 is being channelled as the circulation stream 252, it is important to note that it is the circulation stream 252 that is separated from the reject water 244. As such, the circulation stream flow rate is independent from the rej ect water flow rate as well . Unlike conventional systems, the circulation stream 252 does not return to the feedwater source to be fed to the RO membrane module 120 as feedwater. Circulation stream 252 is only merged with the feedwater 214 along the feedwater conduit 110 before entering the RO membrane module 120 as input stream 212N

[0062] From another perspective, the feedwater flow rate of the feedwater 214 is combined with the circulation flow rate of the circulation stream 252 as the input flow rate of the input stream 12 entering the RO membrane module 120. After filtration, the permeate water exits the RO membrane module 120 at a permeate water flow rate, and the reject water stream is split into the reject water 244 at a reject water flow rate and the circulation stream 252 at the circulation flow rate.

[0063] By having decouple streams 214,252, it is possible to enable precise tuning of recovery ratio and reject water concentration without affecting the RO pump operation, and without requiring flow sensors, automated electronic logic-based flow controllers or synchronized pump control and flow metering.

[0064] Unlike conventional RO membrane systems, where only the recirculation percentage is adjustable, the system 100 enables stable operation under diverse feed conditions and membrane fouling levels.Built-in Passive Cleaning Methods

[0065] System 100 enables passive cleaning of the RO membrane module 120, which may be cleaned by manual high-velocity flushing and / or in-situ cleaning using ionised water from the ioniser or bipolar electrolyser. The high-velocity flushing may be control by adjusting the restrictor valve 142, e g. by fully opening the restrictor valve 142, so that the reject water stream flow rate is increased and the fouling material may be dislodged from the membrane surface by the shear force generated by the high velocity input stream. Both methods are enabled by the hydraulic layout and require no external chemicals, sensors, automated controls or external pumps. It is important to note that the cleaning mentioned here is not the same as the cleaning method by introducing a circulation flow rate spike by increasing the circulation flow rate earlier mentioned. By cleaning the RO membrane module 120, the system 100 is able to extend membrane lifespan, reduce downtime, and minimize the need for frequent, chemi cal -based servicing cycles. In addition, the system 100 enables cleaning without permeate production, external chemical dosing or automation. System 100 may include components like the ultra / nanofiltration unit and manually adjustable variable frequency or speed drives to improve the cleaning efficiency of the system 100.High Reject Concentration Capability

[0066] System 100 is designed to focus on reject water concentration as a key outcome and is engineered to prioritize the concentration of dissolved solids in the reject water stream over permeate purity, achieving up to 3000 ppm Total Dissolved Solids (TDS) even when processing low-salinity feedwater with an initial TDS as low as 100 ppm, in steady state, non-fluctuating, non-batch operations and in the absence of dilution mechanisms. By circulating the circulation stream within a pre-determined flow rate and controlling the reject water flow rate, the concentration of the dissolved solids is able to be increased. This capability is especially valuable for industrial reuse, reject concentration, and zero-liquid discharge applications, where maximizing the concentration of waste streams, i.e. reject water stream, is critical for reducing disposal volumes and enhancing resource recovery.Sensor-Free and Automation-Free Operation

[0067] Unlike conventional systems that rely on sensor feedback and automated electronic logic controllers, as clearly shown, the system 100 is able to operate continuously and reliably without these components. This design significantly reduces system complexity, cost, and maintenance needs, and eliminates the requirement for calibration, software updates, or skilled operators. However, system 100 may include at least one pressure sensor at at least one of the feedwater conduit 110 and the reject water conduit 140, and a controller in communication with the at least one pressure sensor and configured to adjust the circulation pump 152 and restrictor valve 152 to maintain the pressure drop.Stable High Recovery Under Fouling Conditions

[0068] System 100 is able to achieve a high recovery ratio, e.g. above 60% with stable and passive balancing of flow rates and pressures, even under membrane fouling conditions that reduce permeate flux by up to 80% or above 10%, 15%, 20%, 30%, 40%, 50%, 60% or 70% reduced permeate flux.

[0069] When the circulation pump 152 draws circulation stream which is part of the reject water stream, it promotes uniform fouling distribution along the membrane length and avoids localised clogging and pressure spikes and yet enables continued operation with less than a twofold increase in power consumption. Uniform fouling prevents localised clogging or pressure spikes and allows continued operation under high fouling loads. In this way, the system 100 has a high fouling tolerance which enables continuous operation with up to 80% reduction in permeate flux or above 10%, 15%, 20%, 30%, 40%, 50%, 60% or 70% reduction in permeate flux without shutting down. System 100 is able to continue to operate efficientlywithout external chemical dosing, automated cleaning, or real-time electronic control diagnostics, ensuring high uptime and water recovery.Passive Hydraulic Reference Point

[0070] System 100 is able to make use of the low-head circulation pump 152 (<15 psi) to create a stable, self-limiting hydraulic reference point. This passive hydraulic anchor stabilizes system dynamics, prevents over-recirculation, and protects membrane integrity under fouling conditions, all without the need for sensor feedback, purge cycles, or automated electronic feedback controllers. This approach redefines the circulation stream or loop as a membrane- protective mechanism rather than a performance enhancer.

[0071] A hydraulic reference point in a RO system is a stable, self-limiting pressure condition established within the hydraulic circuit, typically by a low-head circulation pump 152 set to a specific maximum pressure (e.g., < 15 psi). This reference point anchors the system’s pressure dynamics, ensuring that the pressure drop across the RO membrane module 120 does not exceed safe operational limits.Removal of Ancillary Components

[0072] As clearly shown, the system 100 is configured to operate without buffer tanks, accumulator tanks, energy recovery devices, or ion-exchange units. This results in a compact, modular, and cost-efficient design that is easier to install and maintain in decentralized or resource-limited environments, further reducing operational complexity and footprint.Modular Scalability Without Centralised Control

[0073] Multiple units of the system 100 may be operated in parallel or series, without or eliminating the need for central synchronisation, supervisory control or electronic automation. Each unit self-regulates through its internal hydraulic balancing, enabling scalable modular deployment in distributed networks or modular treatment setups, which is ideal for industrial, municipal, or decentralized water treatment processes, without complex integration. Hence, the system 100 supports distributed operation, redundancy and capacity expansion. System 100 is modular and scalable, without requiring centralised control.Energy Efficiency Under Changing Conditions

[0074] System 100 is able to maintain an energy consumption below 2.5 kWh / m3under fouled conditions and below 1.5 kWh / m3when clean. This is achieved through passive hydraulic balancing and efficient flow regulation, without energy recovery device, electronic optimisation by automated electronic systems or external chemical cleaning, ensuring cost- effective and sustainable operation. As a result, as the system 100 improves in water recovery or reject concentration, power consumption diminishes. The power consumption, or energy used by the system 100 per hour, in kW, is inversely related to at least one of the recovery ratio, reject water concentration, and circulation flow rate. In other words, the system 100 is not designed to draw excess kW power as the membrane fouling progresses or as the recovery ratio is increased. System 100 in fact has a negative kW correlation with recovery ratio and membrane fouling. For example, if the system 100 draws 2kW for normal fresh membrane or for a standard recovery ratio, e.g. 50% reject and 50% permeate of original feedwater, it does not need to consume more kW but actually consumes less kW when the membrane gets fouled or when the recovery ratio is increased, i.e. more % permeate and less % reject of original feedwater. Consequently, the system 100 need not be upsized to cater for the buffer kW drawn by normal systems to handle such stress situations.

[0075] Under high fouling, the system 100 passively adjusts internal pressure and lowers feed flow to maintain stable operation. Consequently, the power consumption increases slightly but stays below 2.5 kWh / m3, without needing automated electronic optimisation or external chemicals, even under fouled conditions. In clean or low fouling conditions, the system 100 may operate with a recovery rate over 80%, with energy use below 1.5 kWh / m3of feedwater.Environmental and Sustainability Benefits

[0076] By minimizing dependence on external chemicals, electronic parts, and energy- intensive automation, the system 100 is able to support sustainable water reuse and reduces environmental impact. System 100 is able to be configured to be compatible with solar or gravity-fed setups and low-maintenance design and supports sustainable water reuse by maximising recovery and reject concentration, thus further enhances its sustainability profile, making it suitable for long-term, unattended operation in challenging or variable conditions.System 100 is also low in maintenance and therefore reduces environmental impact and operational footprint. In addition, the system 100 does not use consumables or generate electronic waste.Self-Regulating Safety and Recovery

[0077] Passive safety features such as the one-way valve 312 and pressure-limited pump 152 are built into the system 100 to prevent reverse flow through the RO membrane module 120 and over-pressurisation. If the membrane pressure exceeds the head pressure of the circulation pump 152, the one-way valve 312 prevents reverse flow through the RO membrane module 120. This causes the system 100 to stall passively or trigger a circuit breaker, or it may prompt manual actions like valve adjustment or shutdown. These features prevents membrane bypass, protects the system integrity, enable safe shutdown and automatic recovery without alarms, sensors, or electronic interlocks, improving reliability in off-grid or unsupervised environments. System 100 is able to restart automatically once pressure levels return to normal, supporting safe and autonomous recovery.No Software or Firmware Dependencies

[0078] System 100 does not require firmware updates, digital calibration, or automated controllers, reducing cybersecurity risks and long-term obsolescence issues common in smart water systems. This further simplifies operation and maintenance, making the system robust and future-proof.No Startup Sequencing or Priming Needs

[0079] The passive hydraulic design of the system 100 and one-way valve 312 enable the system 100 to be started and stopped without strict sequence requirements, thus ensuring a correct flow upon restart. This feature is especially useful in intermittent or solar-powered applications, where reliable and flexible operation is essential.Compatibility with Intermittent Power Sources

[0080] Due to its passive regulation and minimal electronic reliance, the system 100 works with variable or intermittent power sources, such as solar PV or micro-hydro. It resumes normal operation automatically when power is restored, without needing reinitialization or manual reboot, making it ideal for remote or disaster relief deployments.Maintenance and Lifespan

[0081] As mentioned above, the system 100 does not rely on calibration, sensor replacement, or software updates. However, routine upkeep is still unavoidable. Routine upkeep involves periodic manual flushing, adjusting the restrictor valve 142, and tweaking the variable frequency or speed drives of the circulation pump 152. Membrane replacement is only needed after extended fouling, for example, indicated by a flux loss exceeding 80%, which is passively shown by decreased recirculation effectiveness, where cleaning cycles no longer reduce membrane fouling from 80% to at least 50%. Unlike conventional systems, which require membrane disposal once fouling exceeds 15% due to compaction, scaling, or surface changes that chemical cleaning cannot resolve, the passive cleaning cycles for the system may be performed manually using hydraulic methods, avoiding external chemicals and automated electronic systems that demand skilled personnel.Testing, Validation and Modelling

[0082] Extensive testing, technical validation, and modelling were conducted to verify the full system operation and gather empirical data to support the performance of the system 100. This involved (a) constructing a full-scale prototype and performing long-term empirical testing, (b) benchmarking performance against commercial RO systems, (c) conducting detailed hydraulic modelling and simulation using industry-standard tools, and (d) carrying out failure mode analysis and passive safety validation Each element of the validation process is detailed below.A - Full-Scale Prototype Testing: Demonstrating Unexpected Performance

[0083] Fig. 4 shows a schematic diagram of a full-scale prototype of the system 100. System 100 was constructed using a single-stage four parallel 4" spiral-wound membranes (designedfor an ideal feedwater flow rate of 22 litres per minute at a recovery ratio of 66%-68%), a manually adjustable needle valve 442 (adjusted between 0.0 and 1.0), a low-head (^ 15 psi) circulation pump 452 (max head 15 psi, 0.5 HP at 22 LPM), transparent piping for feedwater conduit 410, permeate water conduit 430, reject water conduit 440, circulation conduit 450, for visual inspection (not shown in Fig. 4), analogue-pressure gauges (not shown in Fig. 4), flow meters (not shown in Fig. 4), and a variable-TDS (100-3000 ppm NaCl equivalent) feed tank (not shown in Fig. 4).

[0084] The prototype operated continuously for 90 days under progressive fouling, with manual dosing of fouling agents (humic acid, colloidal silica, iron oxide) and no reliance on sensor feedback, automation, or external chemical dosing, relying solely on manual and mechanical flow regulation.

[0085] Key measurements included daily recording of flow rates, pressure drops across membrane, TDS levels of feedwater, permeate water, and reject water, and energy usage.

[0086] Results showed stable operation up to 80% permeate flux reduction, recovery ratios above 60% even under fouling conditions, reject concentrations reached up to 3000 ppm from 100 ppm feed without external chemical dosing, energy consumption below 2.5 kWh / m3(in fouled condition) and 1.5 kWh / m3(in clean condition), and obtained with no external chemicals used and low skill operation, i.e. weekly manual adjustment of the valve 142 and VSD.

[0087] Fig. 5 shows an empirical result obtained from the prototype testing.

[0088] Empirical testing showed that benchmark systems consumed more power due to higher water volumes and flow speeds through the RO membrane module 120 compared to the original flow without recirculation, while the system 100 used less power by substantially reducing feedwater due to significantly lower reject water flows. Passive hydraulic balancing maintained steady state pressure balance, allowing the system 100 to operate below 1 MPa, even under fouling.

[0089] The benchmark systems were limited to operating at up to 15% fouling, as further fouling led to excessive pressure drops, as fouling concentrates at the membrane’ s tail-end, reaching the safe operating limit. These systems recorded significantly higher pressure drops compared to the system 100 at 15% permeate flux loss due to fouling. The design of the system 100 promoted more uniform fouling distribution and reduced concentration polarisation along the membrane due to lower solute rejection, decreased operating pressure, and a reduced permeate-to-feed flow ratio as the fouling progresses. By keeping the operating pressure low, the system 100 prevented deep fouling within the membrane mesh and slowed the exponential rise in pressure drop as fouling increased. This allowed safe operation within a 15 psi pressure limit up to approximately 80% fouling, resulting in less frequent maintenance.

[0090] Passive hydraulic balancing enables the system 100 to achieve much higher circulation rates compared to benchmark systems. While conventional systems struggle and become unstable when circulation approaches 100%, primarily because increased pressure and velocity through the membrane limit their ability to circulate beyond 200%, especially during fouling events. System 100 is able to maintain steady state operation with circulation rates up to 500%. This is possible due to the system’s inherent ability to passively hydraulic pressure and flow balancing. At the maximum 500% circulation, the system 100 achieves a membrane permeation ratio close to 15%, which matches the optimal performance point recommended by membrane manufacturers. As a result, the system 100 continues to operate efficiently and in accordance with manufacturer guidelines, even as fouling progresses.

[0091] As fouling within the membrane increased, benchmark systems required more power and energy per cubic metre of feed. In sharp contrast, the system 100 causes power demand to drop significantly as fouling escalated. Although energy usage per cubic metre of permeate did rise with greater fouling, the rate of increase was notably less than that seen in conventional designs.

[0092] By avoiding dramatic power surges that plague traditional systems during fouling, the system 100 simplifies electrical requirements and minimizes strain on automated electronic logic controllers. The result is lower power consumption and dependable operation, even under challenging fouling condition, making maintenance less frequent and reducing operator stress.

[0093] System 100 is able to consistently operate at as little as 20% of its normal water treatment capacity on a steady basis, maintaining stability and requiring no changes to the membrane module 120. In contrast, benchmark systems could not sustain such reduced feedwater flow and would shut down unless additional buffer tanks were introduced. This feature permits the use of a standard system size that can be mechanically adjusted to process up to five times less feed water, offering operational flexibility to match varying demand levels.

[0094] The empirical testing validated the following features of the system 100 (i) the effectiveness of a low-head (<15 psi) circulation pump 152 in establishing hydraulic anchor for passive pressure regulation, (ii) the capability for manual, independent adjustment of reject water and circulation flows, eliminating the need for electronic logic controllers, (iii) sustained operation at high recovery rates (over 60%) even during severe fouling (up to 80% in flux loss), (iv) passive self-cleaning and secure system shutdown without reliance on sensors or electronic automation, and (v) the ability to maintain optimal membrane performance at manufacturer- recommended levels throughout fouling conditions

[0095] Traditionally, achieving high recovery rates in the presence of membrane fouling is believed to require continuous monitoring and regular chemical cleaning. However, the system 100’s ability to deliver these results without relying on automated electronic controllers or external chemical dosing represents a significant departure from standard engineering practices. Being able to self-regulate hydraulically, the system 100 maintains stable performance even during severe fouling and achieves high reject concentrations, all without the need for electronic automation or external chemical dosing, highlighting the system’s counterintuitive and unconventional engineering solution.B - Comparative Benchmarking: Establishing Technical Superiority’ under Fouling

[0096] State-of-the-art commercial single stage RO membrane systems were tested under identical feedwater and fouling conditions. These systems were equipped with automated logic controllers, external chemical dosing for anti-scaling and anti-fouling, energy recoverydevices, and centralised sensor-feedback-based electronic control systems. The conventional RO systems were tested under identical conditions to the system 100.

[0097] Fig. 6 shows a table 600 of parameter and data on the performance between the benchmark systems vs the system 100. The following observations were made:

[0098] Fouling Impact on Recovery Ratio: Conventional systems initially achieved a 68% recovery ratio with new membranes, but this dropped to around 40% with 15% fouling. System 100 initially achieved a 98% recovery ratio with new membranes, which decreased to 97% at 15% fouling, then to 95% at 50% fouling, and finally to 87% at approximately 80% fouling.

[0099] Fouling Impact on Energy Consumption: In the conventional system, the high operating pressure caused the energy consumption to be at 2.7 kWh / m3of permeate with new membranes and further increased to over 4.0 kWh / m3due to 15% fouling, which triggered the first maintenance cycle. However, for the system 100, the lower operating pressure caused the energy consumption to be 1.45 kWh / m3of permeate with new membranes and increased to 2.41 kWh / m3due to 80% fouling, which manually triggered the manual pressure relief shutdown since the pressure drop rose to 13.5, nearing the maximum 15 psi rating of the circulation pump 152.

[0100] Fouling Impact on Reject Concentration: In the conventional system, the reject concentration stays low because the reject flow rate increases with fouling. In the system 100, the reject concentration remains high since the reject water flow rate stays nearly constant despite fouling, with only a slight increase as the pressure drop across the membrane module 120 rises.

[0101] Fouling Impact on Power Consumption: In the conventional system, the power consumption per hour increases significantly due to the higher flow of feed being forced through the same membrane module 120. In the system 100, power consumption per hour decreases because of the reduced permeate water flow rate from the same membrane module 120. Notably, the reject water flow rate and the flow rate of input stream entering the membranemodule 120 remain almost constant, only slightly increasing in response to higher osmotic pressure.

[0102] Thus, it is demonstrated that the proposed system 100’s ability to reject water containing up to 3000 ppm from a 100 ppm feed and maintain steady performance with a high recovery ratio without external chemical dosing under high fouling conditions is a non-obvious result of its unique flow configuration and passive recirculation loop.

[0103] Fig. 7 shows a plurality of charts 700 of the observed operational behaviour between the system 100 and the benchmark systems.

[0104] The charts 700 show the operational behaviour of the system 100 compared to the benchmark conventional systems under various levels of membrane fouling and other process conditions. The results reveal the superior efficiency, energy savings, and robustness of the disclosed system 100. Description for each chart is provided below.

[0105] Recovery Ratio vs Membrane Fouling: This chart indicates that the system 100 maintains a significantly higher recovery ratio across all fouling levels compared to the benchmark. While the benchmark system's recovery ratio declines sharply with increased fouling, the disclosed system 100 sustains high recovery even at 80% fouling. This demonstrates enhanced water recovery efficiency and fouling resistance of the system 100 over the benchmark systems.

[0106] Power Consumption vs Recovery Ratio: System 100 achieves higher recovery ratios with considerably lower power consumption. For instance, at recovery ratios above 90%, the system 100 operates at less than half the power required by the benchmark. This highlights the system 100’s energy-efficient design and optimised hydraulic setup compared to benchmark systems.

[0107] Membrane Inlet Pressure vs Fouling: As fouling increases, the benchmark system requires higher inlet pressures to sustain performance, indicating increased energy demand andstrain on system components. Conversely, the system 100 operates at lower and more stable inlet pressures across all fouling levels, reducing mechanical stress and operational costs.

[0108] Fouling vs Permeate Concentration: System 100 consistently produces permeate with lower total dissolved solids (TDS) across all fouling levels This points to superior separation performance and membrane integrity, even under high fouling conditions, compared to the benchmark, which shows rising TDS in the permeate.

[0109] Fouling vs Energy Consumption: Energy consumption in the benchmark system rises significantly with fouling, whereas the system 100 maintains relatively steady and lower energy use. This emphasises the system 100’s ability to mitigate the energy penalties commonly linked to membrane fouling.

[0110] Recirculation Ratio vs Fouling: System 100 dynamically adjusts the recirculation ratio in response to fouling, reaching up to 500% at 80% fouling. This adaptive control improves shear at the membrane surface, reducing fouling buildup and maintaining optimal performance. Conversely, the benchmark system lacks such adaptability, maintaining a fixed and limited recirculation ratio.C. Hydraulic Modelling: Theoretical Validation of Inventive Architecture

[0111] A dynamic hydraulic model was developed using MATLAB and validated against empirical data. The model incorporated (a) Darcy-Weisbach pressure loss equations and (b) Nonlinear valve flow dynamics. The key simulated scenarios included (i) Baseline: Clean membrane, 100 ppm feed, 15 psi circulation pump 152, 98% recovery (ii) Fouled: 80% flux loss, 100 ppm feed, 15 psi circulation pump 152, 86% recovery (iii) Overpressure: 20 psi circulation pump 152 to test system instability.Darcy-Weisbach Pressure Loss Modelling

[0112] Equation: Pressure drop = friction * pipe length diameter x (water speed):

[0113] Simulation Objectives: The Darcy -Wei sbach equation is used to evaluate the trend of pressure drops in the feed channel based on friction and flow rate. The other dimension-related parameters were irrelevant because the pipe dimensions (length and diameter) remain relatively constant, regardless of fouling. The flow velocity was calculated from the feedwater flow rate and the pipe's cross-sectional area. Since scaling did not significantly alter the pipe dimensions, the velocity and flow rate were directly proportional. Thus, [Pressure drop00friction * (flow rate)2] for this modelling.

[0114] Observations: System 100 exhibited a nearly constant input stream flow speed, resulting in pressure drops that increased almost linearly with friction. This allowed for up to 80% fouling within a safe range of a 15 psi pressure drop. The benchmark system experienced a 15% increase in friction due to fouling and a 50% increase in flow speed caused by water recirculation, leading to a rapid pressure drop close to the safe limit of 15 psi once the membrane fouling reached 15%.

[0115] Model versus Empirical Test: For the benchmark system, the model predicts that the pressure drop will increase by 2.59 times, from 7.78 psi to over 20 psi, when friction increases by 15% (due to fouling) and flow speed rises by 50% (due to recirculation). However, empirical testing shows an actual increase in pressure drop from 7.78 psi to only 12.15 psi, a 1.56-fold rise. This highlights that automated electronic logic control systems are vital for keeping the pressure drop within the safe operating limit of 15 psi, ensuring system stability. In the system 100, the model predicts that the pressure drop should increase by about 2 times when fouling reaches 80% and flow speed increases by 7%. However, the actual pressure drop in empirical tests increases by only 1.73 times. Therefore, the effectiveness of passive hydraulic balancing under fouling conditions is confirmed.

[0116] Conclusion: The Darcy -Wei sb ach model shows that the system 100 maintains pressure stability under fouling through passive hydraulic balancing. In contrast, benchmark systems require active control to stay within safe operating limits. This modelling validation supports the system’s inventive architecture and confirms its non-obvious performance benefits.Nonlinear Valve Flow Dynamics Modelling

[0117] Equation: Pressure drop = (flow valve coefficient)2

[0118] Simulation Objectives: The nonlinear valve flow equation was used to assess the pressure drop trend in the membrane module 120 based on changes in flow rate and valve coefficient, simulating membrane fouling. The fouled membrane was modelled by adjusting the valve 142 from an inverse of 1 to 1.15 for benchmark systems and from an inverse of 1 to 1.8 for the disclosed system 100 to represent their respective 15% and 80% fouling levels.

[0119] Observations: The model demonstrated that the 80% fouling condition should cause an exponential increase in pressure drop, as this model did not include the anchoring effect of the 15-psi circulation pump 152 in the equation.

[0120] Interpretation: The Darcy -Wei sb ach and non-linear valve flow models both conclude that the conventional system fundamentally relies on automated electronic control systems to keep operations within safe boundaries. Both models show that the fouling tolerance of the conventional systems is limited to approximately a 10 to 15% flux loss.

[0121] Model vs Empirical Test: For the benchmark system, the model predicts that the pressure drop should increase 3.1 times when the flow into the membrane module 120 increases by 50% and the valve coefficient is reduced by 15% (due to fouling). This means the pressure should have risen from 7.78 psi to nearly 24.23 psi, which is well above the safe operating limit of 15 psi. However, the actual pressure increase observed during empirical testing is from 7.78 psi to only 12.15 psi; this highlights the importance of the automated electronic controls for the benchmark systems. In the system 100, the model predicts an over 28 times increase in pressure drop when flow increases by just 7% and the valve coefficient drops by 80% due to fouling. Yet, the empirical test shows only 1.73 times increase in pressure drop. This demonstrates the stabilising anchoring effect of the 15-psi circulation pump 152, which prevents the pressure drop from exceeding 15 psi and helps maintain a stable hydraulic balance.

[0122] Conclusion: In RO systems, valve tuning is essential to keep stable operation as fouling progresses. This is achieved via electronic automation in conventional systems, while in thissystem 100, the self-stabilised hydraulics passively sustain optimal flow and pressure in balanced and safe operating conditions.Over-Pressure Feedback Pump (20 PSI)

[0123] Empirical Testing: The test was repeated using a high-pressure circulation pump 152 (20 psi). Increasing the pump head beyond 15 psi caused hydraulic instability, such as: (i) an excessive drop in reject-end pressure; (ii) a surge in feedback flow rate; (iii) pressure across the membrane exceeding 15 psi; (iv) oscillatory flow and undamped pressure fluctuations; (v) increased input stream flow rate, which strains pipes and causes vibrations; (vi) resulting in leaks, pump wear, damage to membrane spacers, telescoping, and compaction. These effects confirmed the non-obvious constraint on pump selection and demonstrated that passive architecture becomes unstable at higher pump heads without electronic control or buffer tanks.

[0124] Modelling: The 15 psi recirculation pump 152 acts as a self-limiting hydraulic reference point, stabilising system pressure without the need for active sensors In the Darcy -Wei sb ach Model, using a 20 psi circulation pump instead of a 15 psi pump 152, with no change in function or physical dimensions, leads the model to predict an excessive increase in flow speed across the membrane. This highlights the importance of electronic controls in maintaining flow speeds and preventing damage to the membrane. The non-linear valve flow modelling further confirms that the flow rate through the membrane increases when using a 20 psi pump instead of a 15 psi pump, with the flow rate rising exponentially at high fouling levels of around 80%.

[0125] This demonstrated that passive architecture is unstable at higher pressure-head pumps without sensor feedback and automated electronic logic controllers. Pumps exceeding 15 psi caused oscillatory flow bursts, pressure fluctuations in the recirculation loop, and recirculation overloads without buffer tanks, confirming the 15-psi limit's criticality.

[0126] Conclusion: The alignment of empirical testing and modelling confirms the predictability and repeatability of the novel design. The use of a low-head pump to passively regulate reject-side pressure is both inventive and counterintuitive, since conventional systemstypically employ high-head pumps and sensor feedback-based automated electronic controllers.D.l Failure Mode Testing: Passive Safety Without Automation

[0127] Testing: System 100 was subjected to induced failure conditions to assess its resilience in the unforeseen event of (i) Membrane blockage, (ii) Pump shutdown, and (iii) Reject-side overpressure.

[0128] Observed Responses: When the membrane becomes blocked, the one-way valve 312 prevents reverse flow through the feedback loop. If the pump shuts down (e g., burnout) or there is overpressure on the reject side (e.g., restrictor valve 142), the system 100 enters a passive stall state without sustaining damage. After maintenance, a manual restart was carried out without reconfiguration. Therefore, no automated electronic alarms, sensor feedback, or automated electronic logic controllers for shutdown were necessary to preserve system integrity.

[0129] Inventive Advantage: Conventional systems rely on automated electronic logic controllers to manage shutdown protocols and sensor-based alarms. The ability of the system 100 to self-protect and recover using only passive components is a notable safety feature that improves reliability in off-grid or unsupervised environments.D.2 Passive Cleaning Modes: Eliminating External Chemical Dependency

[0130] Two cleaning modes were validated: (i) Manual High-Velocity Flush, achieved by fully opening the restrictor valve 142 to increase shear force; (ii) In-Situ Cleaning, using ionised water from a downstream ioniser or bipolar electrolyser.

[0131] Counterintuitive: The conventional benchmark systems rely on external chemical dosing and automated cleaning cycles. System 100 achieves cleaning through hydraulic design alone, requiring only restrictor valve 142 and circulation pump 152 adjustments.

[0132] Maintenance Outcome: The membrane performance was significantly restored, with fouling decreasing from 80% to 50% within 2 hours of cleaning and further to 25% within 1 day, without the use of external chemicals or automated electronic logic controllers. To conserve water, the permeate water was recirculated to the feedwater. These cleaning cycles were integrated into regular low-frequency maintenance routines, reducing downtime and costs associated with conventional high-frequency, external chemical -based servicing cycles.External Lab Testing

[0133] A government-authorised testing laboratory was engaged to collect samples and test the flow rates and TDS of the feedwater, reject water, and permeate water while the system 100 was operating at steady state. The lab report also validated the recovery ratio and power consumption. The test results confirmed (i) the feedwater had a TDS of 568 ppm and a flow rate of 14 litres per minute, (ii) the system 100 operated at a power consumption of 1.2 kW with a 90% recovery ratio, (iii) the permeate water had a TDS of 17 ppm, and (iv) the reject water had a TDS of 2389 ppm. The lab test was repeated using feedwater with a TDS of 252 ppm. The permeate water was found to have a TDS below 10 ppm, and the reject water had a TDS of 893 ppm. These results confirm the system 100’s ability to achieve high recovery, low energy consumption, and high reject concentration without the need for external chemical dosing or automated electronic logic controllers.Conclusion: Demonstrated Counterintuitive Design and Technical Superiority

[0134] System 100 has been thoroughly validated through extensive empirical testing, quantitative benchmarking, detailed hydraulic modelling, failure testing, and external lab testing. The disclosed passive RO system 100 features a counterintuitive hydraulic architecture that (i) eliminates reliance on sensor feedback, automated electronic controllers, and external chemical dosing, (ii) maintains stable, high-recovery performance under fouling and variable salinity conditions, (iii) operates with fully passive safety and cleaning mechanisms, and (iv) surpasses conventional benchmark systems in energy efficiency, recovery, and operational resilience. The results show that the system 100 can be fully implemented and replicated easily. It performs as claimed under extreme fouling and variable feed salinity conditions. These outcomes are unattainable with conventional RO architectures. It operates entirely without theneed for sensor feedback, automated electronic controllers, or external chemical dosing. Such features could still be incorporated, but they are not essential for this passive system 100. Its innovative hydraulic architecture enables passive self-regulation, safety, cleaning, and energy efficiency. These findings are unexpected given the state of the art of conventional systems and represent a clear inventive concept. The system 100’s passive architecture, especially the use of a low-head recirculation pump, manual flow adjustment, and passive hydraulic balancing, collectively provide unforeseen technical advantages that a skilled person would not deduce from existing knowledge of prior art or traditional systems. This level of performance, achieved through passive hydraulic design, marks a groundbreaking advancement in the field of membrane-based water treatment, establishing a new category of mechanically self-regulating, sensor-free, and electronics-independent RO system architecture, optimised for robustness, simplicity, and sustainability in decentralised, industrial, and off-grid applications.

[0135] As evident above, the system 100 does not rely on sensor feedback, electronic automated logic controllers, energy recovery devices, or external chemical dosing systems. Instead, it achieves operational stability, fouling resilience, and energy efficiency through a novel integration of passive hydraulic principles and mechanical flow control elements. Unlike traditional high-efficiency RO systems relying on energy turbines or pressure exchangers, the system 100 achieves comparable energy performance without these components, reducing capital costs, simplifying maintenance, and eliminating the requirement for high-pressure seals or rotating machinery.

[0136] In addition, the system 100 is able to sustain high recovery ratios (above 60%) and maintain stable operation under extreme fouling conditions (80% permeate flux loss), without depending on (i) automated electronic logic controllers, (ii) external chemical intervention, or (iii) frequent shutdowns at only 10-15% permeate flux loss, represents a significant advancement in membrane-based water treatment. System 100 is shown to overcome longstanding limitations of conventional RO systems and introduces a new design approach optimised for robustness, simplicity, and sustainability in demanding environments. Consequently, the system 100 establishes a new class of RO systems that are mechanically self-regulating, energy-efficient, and particularly suited for decentralised, industrial, or off-grid reuse applications, without requiring skilled maintenance personnel or electronic infrastructure.

[0137] Unlike traditional RO systems that aim to minimise permeate TDS, the system 100 is designed to maximise reject concentration. Its flow configuration, which omits dilution mechanisms and recirculates a portion of reject water, enables concentration of reject water up to 3000 ppm, even from low-TDS feed as low as 100 ppm, in steady-state operation without fluctuations or batch / semi-batch states. This is especially beneficial for reject concentration, industrial reuse, or zero-liquid discharge applications

[0138] Given that the system 100 is able to run without electricity, sensors, or external chemicals, the system 100 is ideal for swift deployment in disaster zones or emergency water supplies. Its modular nature allows easy transport and assembly on-site with minimal infrastructure. System 100 is also suitable for applications aiming to reduce reject volume or concentrate reject streams, such as landfill leachate treatment, textile wastewater concentration, or pre-treatment for crystallisers in ZLD systems.

[0139] Essentially, the system 100 is able to be deployed by reusing RO membranes discarded by conventional systems and still deliver comparable or improved results in terms of recovery ratio and energy efficiency.

[0140] A skilled person would appreciate that the features described in one example may not be restricted to that example and may be combined with any one of the other examples.

[0141] The present invention relates to a water treatment system and a water treatment method generally as herein described, with reference to and / or illustrated in the accompanying drawings.

Claims

Claim1. A water treatment system comprising, a feedwater conduit in fluid communication with and upstream of an RO membrane module and adapted to channel feedwater to the RO membrane module to be filtered to produce permeate water and reject water stream, a permeate water conduit and a reject water conduit in fluid communication with and downstream of the RO membrane module, wherein the permeate water conduit and reject water conduit are adapted to channel the permeate water and reject water stream respectively from the RO membrane module, wherein the reject water conduit comprises an restrictor valve adapted to restrict the flow of the reject water through the reject water conduit, a circulation conduit in fluid communication with the feedwater conduit and the reject water conduit, wherein the circulation conduit is connected to the reject water conduit between the RO membrane module and the restrictor valve and connected to the feedwater conduit upstream of the RO membrane module, wherein the circulation conduit is adapted to channel a circulation stream from the rej ect water conduit through the circulation conduit to the feedwater conduit, wherein the circulation conduit comprises a circulation pump adapted to pump the circulation stream through the circulation conduit within a pre-determined circulation pressure, wherein the circulation pump is adapted to direct and combine the circulation stream with the feedwater to form an input stream channelled into the RO membrane module at an input pressure, wherein the reject water stream exits the RO membrane module at a reject pressure, wherein the reject water stream is divided into reject water pushed through the restrictor valve and circulation stream drawn into the circulation conduit, wherein the restrictor valve is configured to maintain the reject pressure within a pre-determined level, wherein the circulation pump and the restrictor valve are configured to maintain a pressure drop between the input pressure and the reject pressure within a predetermined range.

2. The water treatment system according to claim 1 , wherein the feedwater flows through the feedwater conduit at a feedwater flow rate, the circulation stream flows through thecirculation conduit at a circulation flow rate, and the reject water flows through the reject conduit at a reject water flow rate, wherein the circulation flow rate is controlled by the circulation pump and / or the restrictor valve and is independent from the feedwater flow rate and the reject water flow rate.

3. The water treatment system according to claim 2, wherein the circulation flow rate is varied to vary the feedwater flow rate.

4. The water treatment system according to any one of claims 1 to 3, wherein the restrictor valve is adjusted to enable a high-velocity input stream to flush a membrane of the RO membrane module to dislodge fouling material on the membrane.

5. The water treatment system according to any one of claims 1 to 4, wherein the RO membrane module is operable within a pressure range of 0.3 MPa to 1.0 MPa and has pore sizes between 0.08 and 0.12 nanometres.

6. The water treatment system according to any one of claims 1 to 5, further comprising a one-way valve along the feedwater conduit, wherein the one-way valve is adapted to prevent reverse flow of the feedwater.

7. The water treatment system according to any one of claims 1 to 6, further comprising an ultrafiltration (UF) unit in fluid communication with the feedwater conduit, wherein the UF unit is adapted to pre-filter the feedwater before entering the RO membrane module.

8. The water treatment system according to any one of claims 1 to 7, further comprising a nanofiltration (NF) unit in fluid communication with the reject water conduit, wherein the NF unit is adapted to process the reject water exiting the RO membrane module.

9. The water treatment system according to any one of claims 1 to 8, wherein the predetermined circulation pressure head is up to 15 psi10. The water treatment system according to any one of claims 1 to 9, wherein the pressure drop is maintained within a pre-determined range when permeate flux loss in the RO membrane module due to membrane fowling progresses beyond 15% and up to 80%.

11. A water treatment method comprising, channelling a feedwater to a RO membrane module to be filtered to produce permeate water and reject water stream, channelling the permeate water and reject water stream respectively from the RO membrane module, restricting the flow of reject water through the reject water conduit via a restrictor valve, channelling a circulation stream from the reject water conduit through a circulation conduit to the feedwater conduit and directing the circulation stream to combine with the feedwater to form an input stream, channelling the input stream to the RO membrane module at an input pressure, wherein the reject water stream exits the RO membrane module at a reject pressure, wherein the reject water stream is divided into reject water pushed through the restrictor valve and circulation stream drawn into the circulation conduit, wherein the reject pressure is maintained within a pre-determined level by the restrictor valve, wherein the circulation conduit comprises a circulation pump adapted to pump the circulation stream through the circulation conduit within a pre-determined circulation pressure, maintaining a pressure drop between the input pressure and the reject pressure within a pre-determined range by the circulation pump and the restrictor valve.

12. The water treatment method according to claim 1 1, comprising channelling the feedwater stream through the feedwater conduit at a feedwater flow rate, the circulation stream through the recirculation conduit at a circulation flow rate, and the reject water flows through the reject conduit at a reject water flow rate, and controlling the circulation flow rate by the circulation pump and / or the restrictor valve, wherein the circulation flow rate is independent from the feedwater flow rate and the reject water flow rate.

13. The water treatment method according to claim 1 1 or 12, further comprising varying the circulation flow rate to vary the feedwater flow rate.

14. The water treatment method according to any one of claims 11 to 13 , further comprising adjusting the restrictor valve to enable a high-velocity input stream to flush a membrane of the RO membrane module to dislodge fouling material on the membrane.

15. The water treatment method according to any one of claims 11 to 14, further comprising preventing reverse flow of the feedwater.

16. The water treatment method according to any one of claims 11 to 15, further comprising pre-filtering the feedwater using an ultrafiltration (UF) unit before entering the RO membrane module.

17. The water treatment method according to any one of claims 11 to 16, further comprising processing the reject water exiting the RO membrane module using a nanofiltration (NF) unit.

18. The water treatment method according to any one of claims 11 to 17, wherein the predetermined circulation pressure head is up to 15 psi.

19. The water treatment method according to any one of claims 11 to 18, comprising maintaining the pressure drop within a pre-determined range when permeate flux loss in the RO membrane module due to membrane fowling progresses beyond 15% and up to 80%.

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