How to Determine RO Membrane Replacement Criteria and One-Stop Replacement Solutions?

According to the International Desalination Association (IDRA) Desalination & Reuse Handbook (2024–2025), there are currently approximately 23,000 seawater desalination plants worldwide, with a total capacity of 98.98 million m³/day, meeting the water needs of about 300 million people. Other industry data shows that in 2022, the global number of desalination plants had already reached 22,757. Reverse osmosis (RO) technology dominates the sector, accounting for 75% of the global desalination market in 2025. Beyond seawater desalination, the stock of membrane-based water treatment projects in industrial pure water, water reuse, and municipal water treatment is even larger. The global RO equipment market is expected to exceed US$12 billion in 2025. The total number of MBR membrane bioreactor projects worldwide has surpassed 3,400, nearly doubling since 2020.

Currently, global water treatment projects are entering a centralized operation and maintenance phase following large-scale commissioning. The period from 2018 to 2021 saw a peak in the installation of internationally branded RO membranes (Dow, Hydranautics, Toray, Saehan, etc.), with a large number of projects being completed and put into operation during this time. Taking the East Asian market as an example, the design life of internationally branded RO membranes is typically 3–5 years, provided that the feed water quality meets standards (SDI ≤ 3, residual chlorine < 0.1 mg/L, etc.). In industrial applications, membrane elements are generally replaced every 1–2 years. For water treatment projects with a capacity of over 10,000 tons per day, membrane replacement is required every 3–5 years. Some coastal regions in China have already entered a large-scale membrane replacement cycle. The Middle East, Europe, and the Americas are also facing similar concentrated replacement demand.

Based on comprehensive estimates, RO membrane projects using international brands installed between 2018 and 2021 have now fully entered the replacement window. These projects cover both seawater desalination and industrial/municipal sectors.

Seawater desalination sector: Among approximately 23,000 seawater desalination plants worldwide, RO technology accounts for 75%, meaning that more than 17,000 plants are equipped with RO membrane systems. Among these, RO desalination projects that were newly built or expanded between 2018 and 2021 are now entering a concentrated membrane replacement cycle.

Industrial and municipal sectors: Tens of thousands of RO systems worldwide for industrial pure water, water reuse, and municipal water treatment are also facing replacement demand.

According to industry research, approximately one-fifth of membrane water treatment users globally face the need for membrane retirement and replacement each year. Given the concentrated peak installations from 2018–2021, the proportion of projects entering replacement cycles in 2025–2026 is expected to far exceed this average, with some regions (such as coastal China) already clearly in a "large-scale membrane replacement cycle."

The global membrane system replacement service market reached US$18.74 billion in 2025, a year-on-year increase of 9.2%. The membrane system retrofitting and upgrade market was valued at US$1.93 billion, with an expected compound annual growth rate of 8%. Other studies estimate that more than 2 million RO membranes will be scrapped globally each year by 2025 – these figures indirectly confirm the enormous scale of replacement demand.

Behind this large-scale replacement demand lies the core pain points described in this article: high barriers to original equipment manufacturer (OEM) RO membrane maintenance, OEM parts monopolies, long cross-border replacement lead times, and persistently high long-term operation and maintenance costs. The world's top five membrane suppliers collectively hold a 71.5% market share, and this highly concentrated supply structure exacerbates the operational difficulties faced by end users. In 2025, approximately 41% of replacement service contracts have shifted to models such as "pay-per-volume treated" or "asset performance guarantees," reflecting the market's urgent need for cost-effective operation and maintenance solutions.

Compared with generic compatible membrane elements, original imported membranes have highly exclusive maintenance and replacement requirements, with numerous operational restrictions:

1. Closed-loop membrane fault repair with extremely low on-site feasibility

International-brand polyamide RO membranes have proprietary coating, adhesive sealing processes, and internal structures that are fully enclosed and protected by the original manufacturer. Standard global cleaning chemicals and off-line refurbishment equipment are not compatible with the original membrane structure, making routine fault repair extremely difficult:

(1) Limited restoration of scaling and biofouling:

Under conditions of high-hardness surface water, coastal high-salinity raw water, or biochemical reuse wastewater, the membrane surface is highly susceptible to biological slime, inorganic scale, colloids, and oil fouling. Original brand proprietary cleaning chemicals are priced at a premium, with high local procurement costs overseas. If third-party compliant cleaning agents are used, they can easily damage the proprietary anti-fouling coating on the membrane surface, resulting in permanent loss of salt rejection. Measured operational data shows that after non-OEM compliant cleaning, the salt rejection of original membranes can drop from the standard 99.4% to below 85%, rendering them essentially useless.

(2) Physical damage cannot be repaired through component replacement:

Water hammer, pretreatment filtration failure, scratches on the membrane surface from hard particulates, and aging/leakage of end seals are common hardware failures for original imported membranes. All major international brands use integrated sealed packaging processes. The membrane leaf, internal feed spacer, end adapters, and pressure end caps cannot be separately disassembled and replaced. The OEM only provides complete element replacement services – even for minor end damage or seal failures, the entire element must be scrapped and replaced, resulting in very low fault tolerance for repairs.

(3) Chemical corrosion repair requires factory return:

Original imported membranes have a fixed pH tolerance range with low fault tolerance. On-site non-standard acid or alkaline cleaning can cause membrane layer swelling, delamination, or rupture. Local third-party maintenance providers overseas do not have the restoration techniques – the only option is to return the membrane to the OEM's overseas factory for repair. The round-trip logistics and inspection/repair timeline takes 2–3 months, directly causing prolonged system shutdowns at the plant.

When any of the following types of irreversible faults occur in membrane elements, and performance cannot be restored through off-line chemical cleaning or pretreatment optimization alone, complete membrane element replacement is recommended. The criteria fall into three categories: performance degradation, physical structural damage, and operational economics.

(I) Continuous performance deterioration with no recovery after cleaning

Significant salt rejection decline: After correction under standard conditions (25°C, rated operating pressure, fixed recovery rate), salt rejection drops by more than 10%–15% from the initial value of new membranes, with product water TDS and conductivity exceeding limits for extended periods. After 2–3 rounds of standard acid, alkaline, and biological cleaning, salt rejection cannot be restored to the acceptable production range (for conventional industrial membranes, salt rejection below 85% generally renders them useless).

Irreversible permeate flux decline: Under the same operating parameters, system permeate flow drops by 15%–20% compared to new membranes. After excluding external factors such as cartridge filter blockage, low feed water temperature, or insufficient pressure, flow may temporarily recover after cleaning but quickly declines again – indicating compaction of the membrane active layer and permanent blockage of internal flow channels.

Persistent high differential pressure: The inter-vessel differential pressure or overall system differential pressure increases by more than 50% compared to new membranes, resulting in significantly higher energy consumption due to frequent high-pressure operation. After cleaning, the pressure drop reduction is less than 30%, meaning that inorganic scale, colloids, and biofilms have become deeply embedded in the membrane's internal feed spacer layer and cannot be thoroughly removed.

Loss of cleaning frequency control: Routine cleaning intervals that were originally 3–6 months are shortened to monthly or even bi-weekly chemical cleaning. The escalating costs of chemicals, labor, and downtime make long-term operation economically unsustainable.

(II) Irreversible physical/chemical damage with no possibility of repair

Membrane surface scratched by hard particulates, oxidation/hydrolysis, or acid/alkaline corrosion leading to delamination, resulting in persistent turbidity and particulate contamination in the product water. Center tube fracture, membrane roll deformation (telescoping), or seal leakage that cannot be individually repaired. Permanent destruction of the polyamide active layer due to prolonged chlorine exposure exceeding limits or extreme pH operation – no recovery process exists.

(III) Preventive replacement conditions (to avoid unplanned shutdowns)

Membrane elements have been in operation for 3–5 years (5–8 years for seawater desalination membranes), reaching their design service life, with performance entering a rapid decline phase. The original imported brand model has been globally discontinued, with no OEM spare parts or technical support available, making future faults unrepairable.

For older systems with frequent individual membrane failures, partial replacement with mixed new and old membranes can cause hydraulic imbalance, accelerating the scrapping of the entire membrane train. Batch replacement of the entire set is recommended. For overseas installed base of imported membranes from Dow, Hydranautics, Toray, Saehan, and other brands, our company provides a full one-stop service covering pre-sales diagnostics, membrane supply, long-term maintenance, and system retrofitting – meeting the full lifecycle needs of overseas projects:

1. Pre-sales technical diagnostics and solution customization services

●Remote comprehensive water quality testing (TDS, hardness, COD, ammonia nitrogen, turbidity, SDI), combined with on-site operating differential pressure, permeate flow, and salt rejection data, to issue a membrane life assessment report.

●Equivalent replacement selection for old imported membrane models: match replacement membranes of the same size, flow rate, and salt rejection specifications based on the original membrane dimensions, distinguishing between brackish water, anti-fouling, seawater desalination, and low-pressure specialty membranes, providing a side-by-side performance comparison.

●Project operating condition optimization: adjust recovery rate, chemical dosing, and pretreatment processes to extend the service life of existing imported membranes and defer replacement investment.

2. Global supply of full-specification membrane elements

●Our company's stock of equivalent replacement membranes is available off-the-shelf.

●Standard 4040/8040 universal specifications are maintained in inventory. For specialty or discontinued non-standard models, custom production can be arranged. Support for full-container cross-border export, including customs declaration, shipping, and complete export documentation.

●Simultaneous supply of all supporting consumables: FRP vessel end caps, O-rings, connectors, specialty cleaning chemicals, antiscalants, and cartridge filter elements – enabling one-stop consumables procurement.

3. Specialized membrane cleaning, maintenance, and life-extension services

●Equipped with large-scale off-line membrane cleaning equipment for segmented chemical cleaning and physical flushing of repairable imported membranes to remove inorganic scale, biological slime, and colloidal fouling.

●Provide remote 24/7 technical support, with online guidance for overseas operation and maintenance personnel to independently perform routine flushing and simple chemical cleaning procedures.

4. Long-term after-sales and technical training services

●Global membrane element warranty service, including cross-border fault replacement and technical claims for performance abnormalities.

●Online hands-on training for overseas O&M teams: complete standardized courses on membrane disassembly/assembly, fault diagnosis, chemical cleaning, and routine operation management.

●Long-term O&M outsourcing services: annual maintenance agreements covering regular consumables supply, on-site inspections, and annual operation optimization reports.

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We are based in Anhui, China, start from 2011,sell to Southeast Asia,North America,Eastern Europe,South Asia.

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We have an experienced professional technical research and development team. Control system matching ability/R&D and quality control ability. Price advantage brought by supply chain integration capabilities.