Reverse osmosis systems must reliably remove pathogens while maintaining flow rates of 15-50 gallons per day for household units. Current polyamide membranes achieve 99.9% bacterial rejection but face persistent challenges with membrane fouling, which can reduce flux by up to 50% within weeks of operation and create channels for pathogen breakthrough.

The fundamental challenge lies in maintaining consistent pathogen removal while preventing membrane fouling and degradation over thousands of hours of operation.

This page brings together solutions from recent research—including anti-fouling membrane compositions, stabilized biocide treatments, self-purging pressure regulators, and decentralized treatment architectures. These and other approaches focus on ensuring consistent pathogen removal while extending membrane life and reducing maintenance requirements.

1. Water Purification System with Pre-Reverse Osmosis Sterilization Using Non-Oxidizing Biocides

YIDAO NEW ENERGY TECH CO LTD, YIDAO NEW ENERGY TECHNOLOGY CO LTD, 2024

Water purification system that extends membrane life and reduces fouling by sterilizing water before reverse osmosis filtration. The system includes a frame, pump, primary RO device, and interposed sterilizer. The raw water flows through the sterilizer before entering the RO unit to reduce microorganisms, protect the RO membrane, and extend its life. The sterilizer can use non-oxidizing biocides that penetrate sediment and slime, are less affected by pH, and have persistence.

2. Compact Water Purification System with Integrated Composite Filter and Cyclic Pulse Flushing Mechanism

Zhuhai Gree Electric Appliances Co., Ltd., GREE ELECTRIC APPLIANCES INC OF ZHUHAI, 2023

Water purification system for a compact, easy-to-control water purifier that addresses issues of large size, multiple filter elements, and complex flow control in prior systems. The system has a composite filter with pre- and post-filters, a reverse osmosis filter, and a concentrated water treatment unit. It allows cyclic flushing and pulse flushing of the RO membrane by adjusting flow paths. The concentrated water outlet connects to a circulating and pulsing path that alternates. This simplifies flow control compared to separate flushing and discharge paths. It also has an integrated filter element and returns concentrated water to the purifier for processing instead of discharge. This reduces concentration polarization.

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3. Drinking Water Purification System with Sequential Multi-Tank Storage and Pressure Management

NINGXIA ZHONGYI INTELLIGENT WATER SAVING TECH CO LTD, NINGXIA ZHONGYI INTELLIGENT WATER SAVING TECHNOLOGY CO LTD, 2023

A drinking water purification system with multiple storage tanks to prevent back pressure damage to the reverse osmosis membrane. The system has separate tanks for storing purified water. The raw water is treated with multimedia, carbon, and precision filters before going through the reverse osmosis process. A high-pressure pump feeds the reverse osmosis membrane. The purified water goes into one tank, and when that tank is low, water is transferred to the other tank to maintain pressure. This prevents back pressure on the reverse osmosis membrane when the downstream tank is empty.

4. Multi-Stage Water Filtration System with Antiscalant Dosing and Precision Pre-Filtration

NINGXIA ZHONGYI INTELLIGENT WATER SAVING TECH CO LTD, NINGXIA ZHONGYI INTELLIGENT WATER SAVING TECHNOLOGY CO LTD, 2023

Pure water filtration system with improved reverse osmosis performance by preventing scaling of the membrane. The system has multiple stages of filtration before the reverse osmosis unit. It uses a media filter, activated carbon filter, precision filter, and antiscalant dosing assembly. The precision filter removes particles larger than 5 microns to protect the reverse osmosis membrane from scaling. Gauges before and after the precision filter monitor pressure differences to indicate its condition.

5. Water Purification System with Backwashable Reverse Osmosis Membrane and Bypass Pathway

INNER MONGOLIA RONGTONG WATER CO LTD, 2023

Backwashable water purification system with improved reverse osmosis membrane cleaning. The system has multiple features to effectively clean the reverse osmosis membrane without using untreated raw water. The backwash pipeline, pump, and valve allow periodic reversed flow through the membrane to remove impurities. Additionally, a separate path is provided to bypass the membrane during backwash. This allows cleaning without exposing the membrane to raw water. The system also has pre-filtration stages to remove particles and contaminants before reverse osmosis. This prevents membrane fouling and prolongs life. The clean water tanks and sterilizer allow customizing the purification stages and improving overall system efficiency.

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6. Reverse Osmosis Membrane System with Antifouling Sterilizing Filter Plate and Adjustable Flow Grooves

LIANYUNGANG HONGYANG THERMAL POWER CO LTD, 2023

A hydrophilic bactericidal anti-pollution reverse osmosis membrane system that combines multiple filtration stages and sterilization steps to improve water quality. The system uses a specialized antifouling and sterilizing filter plate sandwiched between two reverse osmosis membranes. The plate has filter membranes on one side and a granular activated carbon layer on the other. This allows contaminant filtration and adsorption. The plate also has movable grooves with slides that connect the membranes to allow adjustment for optimal flow. The system also uses bactericidal membranes and hydrophilic filter cloths to enhance sterilization. This multi-stage configuration provides comprehensive water treatment with filtration, adsorption, sterilization, and reverse osmosis steps.

7. Portable Water Purification Unit with Dual Filtration Technologies and Multi-Power Source Capability

Ansa Technologies, Inc., 2023

This is a portable, hand-carrying water purification unit that can filter freshwater or desalinate salt water. It is designed to be rugged, durable, and easily transported in challenging environments. An internal rechargeable battery pack or external power sources can power it. It uses a combination of filtration technologies, including nanofiltration and reverse osmosis, to treat a range of water sources.

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8. Reverse Osmosis Water Treatment System with Multi-Stage Filtration and Separation Components

YANGZHOU YIMING PURIFIER CO LTD, 2023

High-efficiency reverse osmosis water treatment system that provides improved filtration of raw water by utilizing multiple stages of filtration and separation. The system includes a raw water tank, mechanical filter, activated carbon filter, precision filter, reverse osmosis device, cleaning device, and two pumps. Raw water enters the tank, passes through mechanical filtration, carbon filtration, and precision filtration before reverse osmosis. This multi-stage process removes organic matter, dissolved salts, colloids, and microorganisms more effectively compared to using a single reverse osmosis membrane. If a stage fails, the remaining stages can still provide filtration.

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9. Filter Element with Dual Membrane Structure Comprising Reverse Osmosis and Nanofiltration Layers

HAIER SMART HOME CO LTD, QINGDAO HAIER STRAUSS WATER EQUIP CO LTD, QINGDAO HAIER STRAUSS WATER EQUIPMENT CO LTD, 2022

Filter element for water purifiers that reduces fouling and scaling on the reverse osmosis membrane, improving filter performance and longevity. The filter core has a housing, permeable pipe, reverse osmosis membrane, and nanofiltration membrane. The reverse osmosis membrane filters the water and the nanofiltration membrane further filters the concentrated water. This dual membrane setup allows the concentrated water to pass through both membranes, reducing fouling and scaling on the reverse osmosis membrane.

10. Filter Element with Parallel Nanofiltration and Reverse Osmosis Membranes in Dual Chamber Configuration

HAIER SMART HOME CO LTD, QINGDAO HAIER STRAUSS WATER EQUIP CO LTD, QINGDAO HAIER STRAUSS WATER EQUIPMENT CO LTD, 2022

Filter element for water purifiers that extends the life of the reverse osmosis membrane by adding a parallel nanofiltration membrane. The filter element has two chambers, one with a reverse osmosis membrane and the other with a nanofiltration membrane. Raw water enters both chambers, the reverse osmosis membrane filters out impurities and the nanofiltration membrane further filters the water. This reduces the load on the reverse osmosis membrane, prolonging its life, and increases overall water production.

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11. Thin-Film Composite Polyamide Membrane with Metal-Organic Framework Integration

TONGJI UNIVERSITY, 2022

A thin-film composite polyamide reverse osmosis membrane with improved fouling resistance and an efficient preparation method using metal-organic frameworks for water purification. The membrane has antibacterial and anti-biofouling properties to prevent fouling and extend membrane life. The method involves loading a specific metal-organic framework (CuBTTri) into a polyamide thin film on an ultrafiltration membrane substrate.

12. Method for Reverse Osmosis System Maintenance Using Stabilized Hypochlorous Acid Solution

JUSTEQ, LLC, ACCULAB CO., LTD., 2021

Method of maintaining, cleaning, and defouling reverse osmosis systems using a stabilized hypochlorous acid solution as a biocide. The solution is prepared by reacting a chlorine source with a stabilizer in a molar ratio of 1:9 to 9:1. A bromide ion source can be added to produce stabilized hypobromous acid. The biocide is effective at preventing biofouling of RO membranes without harming them.

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13. Reverse Osmosis Membrane with Covalently Bonded Quaternary Ammonium Antimicrobial Layer

Toray Advanced Materials Korea Inc., 2021

Reverse osmosis membrane with resistance to fouling and antimicrobial properties for water purification. The membrane has an outer antimicrobial layer covalently bonded to the polyamide layer of the membrane. A compound from the quaternary ammonium compounds family is used as the antimicrobial agent. This layer surrounds the polyamide layer to prevent fouling and microbial growth on the membrane surface.

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14. Two-Stage Reverse Osmosis System with Multi-Stage Filtration and Ultraviolet Sterilization

KUNSHAN GUANGSHENGYUAN WATER TECH CO LTD, KUNSHAN GUANGSHENGYUAN WATER TECHNOLOGY CO LTD, 2021

Two-stage reverse osmosis water purification system designed for rural households with high salt and polluted groundwater. The system uses multiple filtration stages with ultraviolet sterilization to adapt to varying water qualities. It starts with ball valve, pump, and UV sterilizer for initial treatment. Then super filter, activated carbon, and precision filter stages follow. The final stages are reverse osmosis membranes with UV sterilization. This allows effective purification of heavily contaminated rural water sources.

15. Reverse Osmosis System with In-Situ Permeate Flow Path Biocide Injection Mechanism

ECOLAB USA INC., 2021

Sanitizing the permeate flow path of a reverse osmosis system without disassembly. The method involves injecting a biocide into the permeate compartment while the system is operating, using the unused permeate ports on the end of the system. The injected biocide can sanitize the entire permeate flow path to prevent fouling and bacteria growth.

16. Water Purification Device with Nanofiber Membrane Pre-Treatment and Charged Ultrafiltration Membrane

SHANGHAI MUNICIPAL WATER RESOURCES DEVELOPMENT AND UTILIZATION NAT ENGINEERING CENTER CO LTD, SHANGHAI MUNICIPAL WATER RESOURCES DEVELOPMENT AND UTILIZATION NATIONAL ENGINEERING CENTER CO LTD, 2020

Drinking water purification device that uses a two-stage filtration process to effectively remove contaminants, impurities, microorganisms, and ions from water. The device features functional nanofiber membranes with antibacterial properties for pre-treatment and a charged ultrafiltration membrane for final purification. Physical washing and positive diffusion chemical cleaning are used to maintain membrane performance. This allows reuse and reduces membrane fouling compared to conventional multi-stage filters.

17. Reverse Osmosis Water Purifier with Three-Stage Filtration Including PP Cotton and Composite Sintered Carbon Filter

GUANGZHOU JABER ENVIRONMENTAL PROT CO LTD, GUANGZHOU JABER ENVIRONMENTAL PROTECTION CO LTD, 2020

A large capacity reverse osmosis water purifier that provides high throughput, clean water, and safety at a lower cost. The purifier has a three-stage filtration system. The first stage uses a PP cotton filter. The second stage uses a composite filter made of PP cotton and sintered carbon rods. The third stage is a reverse osmosis membrane. This sequence removes particles, impurities, and contaminants before the final purification step. The composite filter allows higher throughput compared to just carbon. The PP cotton in the first stage prevents clogging of the later stages. The lower cost is from using PP cotton and sintered carbon instead of expensive activated carbon.

18. Compact Multi-Stage Water Filtration System with Integrated Control and Monitoring Devices

TIBET HUAYANG HEATING ENG SERVICE CO LTD, TIBET HUAYANG HEATING ENGINEERING SERVICE CO LTD, 2020

A compact plateau water filtration system for purifying raw water into drinking water in a high altitude environment. The system has a purification device with multiple filtration stages including softening, media filtration, activated carbon, demineralization, and reverse osmosis. It also has a control device with solenoid valves to regulate water flow and a monitoring device with pressure gauges to track filtration performance. The system is compact, easy to clean, replace components, and monitor water quality compared to large traditional systems.

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19. Multi-Stage Filtration System with Sequential Quartz Sand, Activated Carbon, Sodium Ion, Precision, and Reverse Osmosis Filters

ZHANGJIAGANG CITY YUFENG BEVERAGE MACHINERY CO LTD, 2020

Purified water production line with improved filtration efficiency to meet drinking water standards. The line has multiple filtration stages including quartz sand, activated carbon, sodium ion, precision, and reverse osmosis filters. This stepwise filtration removes impurities like particles, heavy metals, chlorine, colloids, and solutes. The reverse osmosis stage further purifies the water by removing solvents and dissolved substances.

20. Central Water Purification System with Multi-Stage Treatment and Flow Splitting

YUQ ENVIRONMENTAL SYSTEM CO LTD, YUQ GUANGDONG ENV SYSTEM CO LTD, 2020

A central water purification system that provides high-quality water for various purposes beyond just drinking water. The system has a central pre-treatment, central processing, membrane separation, and outlet stages. It uses reverse osmosis, filtration, UV disinfection, and flow splitting to produce separate streams of purified, RO drinking, NF drinking, and domestic water. The system also has automated cleaning and concentrated waste collection to save water.

21. Nanoporous Polyethersulfone/Polyethylene Oxide-Polysilsesquioxane Blend RO Membrane with Hydrophilic Pore Polymers and Cross-Linked Polyamide Layer

UOP LLC, 2020

This is a reverse osmosis (RO) membrane for water purification that has high flux (permeability), high rejection (of contaminants), and fouling resistance. The membrane includes a nanoporous polyethersulfone/polyethylene oxide-polysilsesquioxane blend support membrane with hydrophilic polymers inside the pores and a thin layer of cross-linked polyamide on the surface. This unique composite structure provides high performance for water treatment applications.

22. Multi-Stage Filtration and Purification System with Compressed Carbon, Media, Softening, Reverse Osmosis, and UV Sterilization Stages

HANGZHOU WEILAIYILAI TECH CO LTD, HANGZHOU WEILAIYILAI TECHNOLOGY CO LTD, 2020

Direct drinking water system with multi-stage filtration and purification to produce high-quality, healthy drinking water. The system includes stages of compressed carbon filter, media filter, water softening, reverse osmosis (RO) membrane, and UV sterilization. This multi-stage filtration removes impurities, softens water, removes contaminants, and further purifies through RO and UV to provide direct drinking water that meets World Health Organization standards for healthy water.

23. On-Demand Water Treatment System with Integrated Pre-Filtration, Carbon Block Filtration, Reverse Osmosis, and Chlorine Dosing

The Coca-Cola Company, 2019

An on-demand water treatment system provides safe, potable water from wells and municipal sources without needing storage tanks. The system includes pre-filtration, carbon block filtration, and reverse osmosis to remove contaminants. An automatic chlorine doser maintains disinfection. The absence of storage tanks reduces complexity and maintenance. The system can be powered by DC sources like solar panels for remote operation.

24. Reverse Osmosis System with Ultrafiltration Pretreatment and Backwash Integration

Nanjing Shuibeizi Water Purification Technology Co., Ltd., 2019

Reverse osmosis water treatment system with ultrafiltration pretreatment to improve reverse osmosis membrane longevity and stability by using ultrafiltration instead of traditional multi-media and activated carbon filters. The system has a raw water pump, ultrafiltration module, reverse osmosis host, and water tanks. The raw water enters the ultrafiltration module, then the filtered water goes to the reverse osmosis host. This removes particles and impurities from the reverse osmosis feed, reducing membrane fouling and extending life. The concentrated water from reverse osmosis is backwashed through the ultrafiltration module to clean it.

25. Reverse Osmosis Water Purifier with Multi-Stage Membrane Series Connection and Two-Way Flocculation Flushing System

Hefei Gemei Electric Co., Ltd., 2018

R0 type reverse osmosis water purifier with improved recovery rate, flushing efficiency, and fouling prevention. The purifier uses a multi-stage membrane series connection with partial water recirculation to increase recovery. It also has two-way flocculation flushing instead of post-production flushing. An automatic interlock protection system dissolves scale and removes fouling to extend membrane life. The system has sensors for leakage, overpressure, overload, shortage, and a microcontroller to manage components like pumps, valves, and alarms.

26. Five-Stage Reverse Osmosis System with Sequential Filter Arrangement

Yingyan Industrial (Shanghai) Co., Ltd., 2018

A five-stage reverse osmosis water purification system with improved efficiency. The system uses a sequential arrangement of filters in a specific order: PP cotton fiber filter, granular activated carbon filter, sintered activated carbon filter, reverse osmosis membrane, and post-activated carbon filter. This order allows effective primary filtration of water impurities through the first three filters, followed by reverse osmosis to remove salts and contaminants, and finally a final activated carbon filter to further polish the water. This step-by-step filtering sequence enhances overall purification efficiency compared to adding all filters together.

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27. Multi-Stage Filtration System with Sequential Low-Pressure Membrane and Ozone Integration

Anhui Lijing Environmental Protection Technology Co., Ltd., 2018

A self-osmotic water purification system that avoids the high pressure issues of reverse osmosis by using a sequence of filtration steps instead of a single high-pressure membrane. Water enters the system through a raw water tank, is filtered through a sediment filter, activated carbon filter, cationic softener, and high pressure pump before going through a low-pressure RO membrane. This prevents bursting of high-pressure components like pipes and membranes. The filtered water is then mixed with ozone and further filtered before storage.

28. Multi-Stage Membrane Water Treatment System with Sedimentation, Filtration, Ultrafiltration, and Ultra-Low Pressure Reverse Osmosis

Sound Eco Technology Co., Ltd., 2018

Membrane water treatment system and method for producing high quality drinking water from sources with poor water quality. The system involves a multi-stage treatment process using sedimentation, filtration, ultrafiltration, and reverse osmosis. The stages are: primary sedimentation, self-cleaning filtration, submerged ultrafiltration, and ultra-low pressure reverse osmosis. This multi-stage membrane treatment allows achieving stricter water quality standards by removing impurities that are not effectively removed by traditional water treatment methods.

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29. Reverse Osmosis Water Purification System with Sequential Ultrafiltration and Reverse Osmosis Modules

Harbin Haowei Weiye Technology Development Co., Ltd., 2018

Reverse osmosis water purification system with improved filtration performance and component longevity. The system uses an ultrafiltration membrane module followed by a reverse osmosis module. This two-stage filtration process provides better purification compared to just reverse osmosis. It also reduces the frequency of membrane replacements since the ultrafiltration module removes larger contaminants before reverse osmosis. The system includes a booster pump, high pressure pump, and ultraviolet sterilizer for additional purification steps.

30. Water Purification System with Separate Clean Water Channel for Membrane Rinsing and Fouling Prevention

2017

Water purification system that reduces fouling and scaling on membranes in reverse osmosis and other filtration processes. The system has a separate channel for clean circulating water that doesn't contain contaminants. This clean water is used to rinse the membranes and flush out fouling organisms and scale deposits. This prevents buildup on the membranes that can increase operating pressure and reduce performance. The separate channel also prevents contaminants from the feed water from directly contacting the membranes.

31. Reverse Osmosis Membrane Device with Integrated Anti-Seepage Ring and Multi-Layer Filtration System

ZHENG DUANJIN, 2016

A reverse osmosis membrane device with high efficiency, long life, activated carbon filtration, and disinfection capabilities. The device has a reverse osmosis membrane enclosed in a casing with an inlet, outlet, and filter layers. The membrane is connected to a raw water inlet, permeate channel, and anti-seepage ring. The ring has separate outlets for pure water and waste water. The pure water outlet has a filter layer. The casing has an outer package. The design provides high pure water filtration, desalination, long life, carbon filtration, and disinfection advantages.

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32. Water Treatment Process with Pre-Filtration and Periodic Membrane Cleaning for Reverse Osmosis Systems

TORAY INDUSTRIES INC, 2015

A water treatment method to efficiently produce fresh water with reverse osmosis membranes while suppressing fouling. The method involves pre-filtering the water using a porous membrane to capture large particles, microbes, and organic matter before reverse osmosis. After each pre-filtration cycle, the porous membrane is cleaned to remove fouling. This allows the reverse osmosis membrane to have lower fouling since it receives pre-treated water with reduced contaminants. The cleaning steps are repeated every 3-30 hours to balance fouling prevention and membrane life.

33. Hybrid Water Purifier with Sequential Reverse Osmosis and Ultrafiltration Membrane Stages

SHENZHEN COCABO DRINKING WATER EQUIPMENT CO LTD, 2015

A water purifier with a reverse osmosis membrane and ultrafiltration membrane that reduces waste water and improves efficiency. The purifier has two membrane stages, reverse osmosis and ultrafiltration, connected in a hybrid configuration. The waste water from the reverse osmosis stage goes through the ultrafiltration stage again to further purify it. This double filtration reduces the waste water compared to a single stage reverse osmosis purifier. It also allows the membranes to self-clean by washing each other during operation.

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Pathogen removal with reverse osmosis for clean drinking water is one of the surefire ways to get rid of the harmful pathogens contaminating water. Reverse osmosis technology filters out this contamination through a semipermeable membrane. This way, the person gets purified water without having to worry about diseases.

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