RO Membrane Fouling Prevention

A simple and effective reverse osmosis membrane cleaning method and agent that can clean and sterilize the membrane in a single step using a composite cleaning solution containing hydrochloric acid, citric acid, surfactant, and bactericide. The method involves circulating this cleaning solution through the membrane system at elevated temperature to remove inorganic scale, organic fouling, and bacteria. The citric acid complexes with ions to enhance scale removal, the hydrochloric acid provides initial cleaning, and the surfactant and bactericide prevent re-fouling. This one-step cleaning eliminates the need for multiple cleaning steps and allows rapid and effective membrane restoration.

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Real-time monitoring of reverse osmosis (RO) membrane fouling to enable early detection, characterization, and mitigation of fouling. The technique involves isolating the permeate of a lead or tail element in each stage of an RO system and measuring its flux and rejection directly. This provides much higher sensitivity and faster detection of fouling compared to monitoring the entire stage or system. By isolating the lead or tail element permeate and measuring its performance, fouling can be detected several times faster. This allows for more targeted and effective fouling management strategies.

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Cleaning method for reverse osmosis membranes fouled by proteins and polysaccharides to restore water production. The cleaning process involves four steps: (1) cleaning with citric acid and sulfamic acid, (2) cleaning with urea and surfactant, (3) cleaning with sodium tripolyphosphate and sodium citrate, and (4) repeating step 1. The cleaning steps use specific chemical solutions and pH ranges to effectively remove the protein and polysaccharide fouling from the reverse osmosis membranes.

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Cleaning nanofiltration membranes using microbubbles to improve cleaning effectiveness and reduce fouling compared to conventional cleaning methods. The method involves preparing cleaning water with microbubbles by dissolving gases into the cleaning solutions. The microbubbles are used to clean the membranes by rinsing, acid cleaning, alkaline cleaning, and repair agent cleaning steps. This microbubble cleaning process provides better fouling removal and membrane recovery compared to traditional cleaning methods.

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Reverse osmosis membrane cleaning device and method for online cleaning of RO membranes to improve performance and prolong membrane life. The device has a cleaning unit, production unit, dosing unit, bypass monitoring unit, and control unit. The method involves diagnosing membrane fouling based on factors like water quality changes, then triggering cleaning modes tailored to the fouling type. Cleaning mode 1 is for inorganic fouling with calcium, magnesium, carbonate, and chloride. Cleaning mode 2 is for fouling with sulfate, fluoride, and organic compounds. The cleaning solutions contain acids, alkali, salts, and biocides. The device automatically dispenses the optimized cleaning solutions based on the diagnosis.

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A reverse osmosis membrane cleaning agent for organic fouling that effectively removes organic matter, microorganisms, and dirt from membrane surfaces. The cleaning agent contains specific components in optimized proportions. These include: 1% anionic surfactant (like sodium dodecyl benzene sulfonate), 25-35% chelant (like EDTA), 8-10% antioxidant, 0.1-0.3% aprotic solvent (like N-methylpyrrolidone), 0.5-1% fungicide (like 2,2-diao-3-nitropropionamide), and pH adjuster as needed. The components are chosen for their synergistic fouling removal properties. The anionic surfactant helps strip biological slime, chelant removes

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Cleaning method for desalinated reverse osmosis membranes in water treatment systems to maintain membrane performance and prevent fouling. The cleaning involves specific steps based on the type of contamination. For organic fouling, alkaline cleaning is followed by acid cleaning. For inorganic scale fouling, acid cleaning is followed by alkaline cleaning. The cleaning steps include soaking the membranes in cleaning solutions, rinsing with water, and using high quality water without residual chlorine.

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A liquid separation membrane with improved fouling resistance for applications like reverse osmosis and ultrafiltration. The membrane has a base material with a porous layer and a coating layer that covers part of the surface. The coating layer contains an oil-repellent polymer. The oil-repellent polymer can contain fluorine-containing monomers and/or antibacterial monomers. The coating layer adheres to the base material via forces like crosslinking, van der Waals, ionic, hydrogen bonding, and anchoring. The membrane prevents fouling by reducing protein adsorption and oil accumulation on the surface.

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A method for cleaning reverse osmosis membranes in water treatment systems to improve cleaning efficiency and prevent dirt transfer between stages. The method involves sequentially flushing and soaking each membrane section with acidic, neutral, and alkaline cleaning agents. The membranes are separated during cleaning to prevent dirt from front stages washing into later stages. This prevents excessive sediment buildup and maintains membrane performance.

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Water treatment method for improving water quality in a membrane filtration system. The method involves adjusting the chemical cleaning conditions of the membrane based on the Silt Density Index (SDI) of the filtered water. When the SDI exceeds a reference range, the chemical cleaning frequency, contact time, concentration, temperature are adjusted to improve filtration performance. By changing the cleaning conditions based on the SDI, it allows optimizing the cleaning parameters to maintain water quality when the SDI deviates from the reference range.

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Online reverse osmosis membrane cleaning method and device that allows removing fouling from operating reverse osmosis membrane modules without disassembly. The cleaning involves cyclic alkaline washing, pickling, and flushing. The method improves membrane flux recovery and fouling removal compared to offline cleaning. The device connects to the membrane module's concentrate outlet and feed inlet. It pumps cleaning solutions through the module during operation. The alkaline wash removes organic matter, pickling dissolves inorganic deposits, and flushing rinses.

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An improved method for chemically cleaning reverse osmosis membranes to prevent fouling buildup that can clog the membranes and reduce performance. The method involves circulating the cleaning solution from the back of the membrane array towards the front during chemical cleaning, instead of feeding from the front as in traditional cleaning. This prevents front-end fouling from blocking the back-end grid channels during cleaning. The cleaning solution is circulated using the membrane element's former pump to reverse the flow direction.

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Composite reverse osmosis membranes for water purification and desalination have improved fouling resistance and water permeability. The membranes have a modified polyamide skin layer on a porous support. The modification is done by treating the polyamide with an alkylenediamine derivative after interfacial polymerization. This modification improves the antifouling properties of the membrane compared to unmodified polyamide membranes.

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Membrane separation technology with improved separation performance and durability for applications like ultrapure water, food processing, desalination, metal extraction, etc. The membrane has a porous substrate layer and an active layer on top that is partially crosslinked and contains a superhydrophilic agent. The active layer with crosslinked superhydrophilic agent enhances water flux and separation efficiency compared to unmodified layers. The membrane can be made by coating the substrate with intermediate layers, then the active layer containing the superhydrophilic agent, and drying.

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Preparing an anti-fouling, wetting-resistant composite membrane distillation membrane to improve performance and stability of membrane distillation systems for treating high-salt wastewater. The method involves modifying the surface of hydrophobic microporous membranes to make them more hydrophilic, then coating them with a mixture of tannic acid and polyvinyl alcohol. This composite membrane has both oil pollution resistance and surfactant wetting resistance. The hydrophilic coating prevents foulants from adhering to the membrane and blocking pores, while the tannic acid provides oleophobicity to prevent oil passage. The composite membrane maintains high flux and rejection for long-term operation stability.

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A chemical cleaning system for high organic fouling membrane elements in reverse osmosis and nanofiltration systems used to treat organic wastewater. The system allows efficient chemical cleaning of multiple sections of membranes without disassembly. The membrane sections are connected in series and a cleaning pool is added between sections. Cleaning agents like disinfectants, phosphates, and acids are added to the pool and circulated through the sections. This allows targeted cleaning of fouled sections without disassembly and reduces overall cleaning agent usage.

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High-efficiency two-stage RO water treatment system that improves efficiency, reduces energy consumption, and extends membrane life compared to conventional two-stage RO systems. The system has a pre-treatment unit, a secondary RO unit, a post-treatment unit, and separate flushing and cleaning units. The pre-treatment unit sterilizes and scales the feed water before sending it to the secondary RO unit. The secondary RO unit has dedicated flushing water to prevent membrane fouling. The cleaning unit provides chemical cleaning water to periodically clean the secondary RO membranes. This prevents fouling, maintains efficiency, reduces operating pressure, and extends membrane life compared to shared flushing in conventional two-stage RO systems.

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Polyamide reverse osmosis membrane with excellent durability and antifouling properties for desalination applications. The membrane has a layered structure with a polymer support layer, a polyamide active layer, an antifouling layer, and a protective coating. The antifouling layer contains a crosslinked polymer made from a primary amine compound and a polyfunctional acid halide. This layer provides antifouling resistance. The protective coating prevents chlorine degradation. The layered structure improves membrane durability and fouling resistance compared to traditional membranes.

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Preventing reverse osmosis membrane fouling for water purification with enhanced performance. The membranes have a protective layer made from a composition containing a specific polymer material that improves salt and boron rejection while maintaining high flux. The composition includes a material with a specific chemical formula, molecular weight, optional hydrophilic polymers, and crosslinking agents.

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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.

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