BW30-400/34i Brackish Water RO Membrane High Rejection Industrial Element

BW30-400/34i brackish water RO membrane is an 8-inch spiral wound polyamide TFC reverse osmosis element built for medium-salinity raw water treatment. Equipped with 34mil thick feed spacer and exclusive iLEC interlocking end caps, it delivers 99.6% stable salt rejection and 11,000 GPD standard permeate flow. Wider flow channels lower fouling risk, broad pH tolerance simplifies chemical cleaning, while interlocking end caps eliminate O-ring leakage failures. It cuts long-term water production cost for municipal water supply, power plant demineralization, chemical factory wastewater reuse and well water desalination, becoming a mainstream industrial brackish water filtration core component widely searched by global water treatment engineers and project contractors.

Product Description

Global industrial water treatment projects face two core pain points when handling brackish well water, surface saline water and recycled industrial wastewater: unstable salt rejection that fails to meet permeate standards, and frequent membrane fouling caused by suspended solids, organic matter and mineral scaling, which leads to frequent shutdown cleaning and high replacement expense. The BW30-400/34i RO membrane element is developed as a standardized 8040 size brackish water reverse osmosis solution targeting these universal industry troubles. Adopting mature polyamide thin film composite membrane sheet as core filtration medium, it carries 400 sq.ft of effective active membrane area, far exceeding traditional 365 sq.ft membrane elements of the same specification, which brings larger single-element water output without raising operational flux load. Standard working parameters are calibrated under 2000ppm NaCl brackish water benchmark environment, with stabilized salt rejection up to 99.6% and minimum guaranteed rejection above 99.4%, maintaining consistent permeate TDS value under long-term continuous operation. This model belongs to classic BW series brackish water RO products, compatible with all mainstream 8-inch membrane pressure vessels on the market, without extra modification cost for existing water treatment equipment renovation projects. It is specially designed for raw water with salinity below 10,000ppm, covering most underground well water, river brackish water and factory secondary wastewater reuse raw water sources, filling the demand gap of high-flow, stable-desalination industrial RO elements for medium-salinity water systems.

Different from ordinary thin-channel RO membrane elements on the market, the suffix "/34" of BW30-400/34i stands for 34mil thick feed spacer, which is the core structural difference distinguishing it from conventional 28mil thin spacer membrane products. Thin feed spacers easily form stagnant water zones during water circulation, enabling calcium, magnesium, silica and organic pollutants to deposit and adhere to membrane surface rapidly, triggering pressure difference rise and rapid performance decay. The widened 34mil flow channel maintains uniform turbulent flow inside the element all the time, reducing the retention time of foulants on membrane surface fundamentally. Meanwhile, the suffix "i" represents built-in iLEC interlocking end cap technology, replacing traditional separate end cap and O-ring assembly structure. Traditional split end caps have assembly gaps; under long-term pressure fluctuation, O-rings shift and leak, causing concentrated salt water to mix into permeate and deteriorate outlet water quality. The integrated interlocking end cap eliminates assembly gaps, realizing seamless connection between multiple membrane elements inside one pressure vessel, thoroughly solving cross-contamination leakage risks inside the membrane shell. The whole element adopts integral fiberglass winding shell, with strong compression resistance and corrosion resistance, adapting to harsh industrial water treatment workshop operating environment without deformation or shell cracking under frequent pressure rise and drop cycles.

Technical Features

Polyamide TFC Membrane Sheet Formulation:

The core filtration medium of BW30-400/34i adopts upgraded polyamide thin film composite membrane sheet with double-layer surface modification treatment. The surface dense desalination layer forms uniform nano-scale separation pores, which can effectively intercept dissolved inorganic salts, heavy metal ions, colloidal silica, microbial colonies and macromolecular organic pollutants in brackish water, without missing small molecular salt ions that easily pass through ordinary low-end RO membranes. The bottom support layer uses high-strength non-woven polyester fabric, which enhances the tensile resistance of membrane sheet and avoids membrane layer cracking under long-term high-pressure water flow impact. The membrane surface is added with hydrophilic coating formula, reducing the surface tension between water and membrane material, lowering the adsorption force of organic foulants on membrane surface, and slowing down the formation of organic pollution layer. Compared with unmodified conventional polyamide membrane, the hydrophilic modified sheet extends the stable operation cycle by 30% under equal raw water pollution index, and shortens the chemical cleaning duration by nearly half when cleaning is needed, greatly improving the overall operation efficiency of the water treatment system. The whole membrane sheet production process adopts fully automatic precision coating equipment, controlling membrane thickness error within ±0.1μm, ensuring consistent desalination performance of every single membrane element without individual performance deviation.

34mil Wide Feed Spacer Flow Channel Technology:

The exclusive 34mil thick feed spacer flow channel design is the core technical feature of BW30-400/34i distinguishing it from standard narrow-channel brackish water RO membranes. The thickened plastic spacer enlarges the internal circulation space of the element, weakening the flow resistance of raw water inside the membrane, so the system operating pressure can be properly reduced under the same water output requirement, cutting the energy consumption of high-pressure pump correspondingly. Wider flow channels reduce the accumulation of particulate dirt inside the element; during online chemical cleaning, cleaning agent can fully contact all membrane surfaces without blind cleaning dead zones, improving pollutant stripping efficiency. For raw water with SDI value between 3-5, which is common in well water projects, thin 28mil spacers will quickly block with sediment and colloids within 1-2 months, while 34mil spacers can maintain stable pressure difference for more than 4 months under identical pretreatment conditions. The spacer material uses food-grade modified polypropylene, resisting acid and alkali corrosion in chemical cleaning liquid, no plastic debris shedding to pollute the membrane layer during long-term flushing and cleaning cycles. The staggered grid structure of the spacer guides raw water to form cross-flow turbulent flow, scouring the membrane surface continuously during operation, realizing passive self-cleaning effect and delaying the rise of cross-membrane pressure difference.

iLEC Interlocking End Cap Sealing Structure:

Built-in iLEC interlocking end cap sealing technology optimizes the internal connection mode of multi-element membrane vessels, solving the long-standing leakage pain point of traditional split end cap RO membranes. Traditional membrane elements rely on independent O-rings between every two elements for sealing; during equipment transportation, system pressure fluctuation and regular element replacement, O-rings are easy to shift, deform or wear, causing brine leakage into permeate side and sharp drop of outlet water quality. The interlocking end cap integrates positioning and sealing structure as one unit, adjacent membrane elements directly lock and connect without separate O-ring filling between them, completely eliminating internal cross-leakage risk of membrane shell. The end cap raw material is high-toughness ABS engineering plastic, with strong anti-aging performance, resistant to long-term immersion in raw water and cleaning agents, no brittle cracking under alternating cold and hot working temperature. The central permeate collection tube adopts thickened PVC pipe with uniform permeate hole distribution, balancing the flow velocity of produced water on all membrane surfaces, avoiding local excessive flux that accelerates membrane fouling. The whole end cap assembly is one-time injection molding, without secondary assembly gaps, the sealing performance remains stable within the full service life of the membrane element.

Ultra-wide pH Chemical Cleaning Tolerance System:

BW30-400/34i is equipped with an optimized membrane material anti-corrosion formula, supporting 1–13 full-range pH cleaning environment, which is a prominent technical advantage over ordinary brackish water RO membranes with narrow cleaning pH range limited to 2–11. In actual industrial operation, organic pollution needs alkaline cleaning liquid with pH 12-13 to decompose biological slime and oil stains, while mineral scaling requires acidic cleaning liquid with pH 1-2 to dissolve calcium carbonate, barium sulfate and silica scale. Narrow pH resistant membranes will suffer irreversible membrane layer damage under strong acid or strong alkali cleaning, leading to permanent decline of desalination rate. This model’s modified polyamide membrane sheet maintains complete structural stability under short-term strong acid and strong alkali cleaning (within 30 minutes), without hydrolysis or pore expansion of the separation layer. The fiberglass shell and plastic end caps also match the wide pH cleaning standard, no corrosion or layer peeling during repeated acid and alkali cleaning cycles. The broad pH tolerance allows water treatment operators to select more efficient cleaning chemical agents according to actual pollution types, thoroughly remove composite pollution mixed with organic matter and inorganic scale, restore membrane performance to factory standard after each cleaning operation.

Core Advantages

Ultra-stable High Salt Rejection Rate:

The primary competitive strength of BW30-400/34i lies in its 99.6% stabilized salt rejection rate, which can continuously control permeate TDS at ultra-low level even under fluctuating raw water salinity. For industrial projects with strict outlet water standards such as power plant boiler makeup water and electronic factory deionized pre-water, stable high rejection avoids frequent adjustment of post-processing ion exchange or EDI equipment, reducing the consumption of ion exchange resin and electric energy of EDI modules. Compared with low-rejection brackish RO membranes with 99.0% rejection, under raw water salinity of 2000ppm, the permeate TDS of this product decreases by more than 50%, greatly lowering the load of subsequent polishing treatment equipment. Even after multiple chemical cleaning cycles, the minimum guaranteed salt rejection still stays above 99.4%, without obvious performance attenuation in the middle and later service life. This consistent desalination performance helps engineering contractors pass water quality acceptance stably, reducing after-sales maintenance caused by unqualified permeate water, and improving project delivery satisfaction for global water treatment system integrators.

Lower Long-Term System Operating Cost:

Adopting BW30-400/34i can comprehensively cut the full life-cycle operating cost of brackish water treatment systems, reflected in three dimensions of energy consumption, cleaning frequency and replacement cycle. First, the 34mil wide feed spacer reduces internal flow resistance, the high-pressure pump can operate under relatively low pressure, cutting power consumption by 12%-18% annually compared with narrow-channel membrane elements under equivalent water yield. Second, wide flow channel and hydrophilic anti-fouling membrane surface slow down pollution accumulation speed, the chemical cleaning cycle extends from 1-2 months to 3-4 months, reducing chemical agent purchase cost and equipment downtime loss caused by shutdown cleaning. Third, wide pH cleaning tolerance avoids permanent membrane damage from improper cleaning, the average service life reaches 3-5 years, 1 year longer than conventional brackish RO membranes, lowering annual membrane replacement procurement expense. For medium and large-scale water treatment systems with daily water output above 500 tons, the cumulative saved operation cost within 3 years can offset the slight price difference between this model and ordinary standard membranes, presenting obvious economic benefits for long-term continuous operation projects.

Universal Compatibility & Simple On-site Installation:

Universal compatibility with all standard 8-inch RO pressure vessels is a prominent practical advantage of BW30-400/34i for global buyers. The 8040 standard dimension (8 inch diameter, 40 inch length) matches all mainstream brand membrane shells on the market, whether new system construction or old equipment renovation, no customized membrane shell, adapter or pipeline transformation is required, saving engineering transformation material cost and construction period. The iLEC interlocking end cap simplifies on-site installation steps: operators only need to align two membrane elements and push to complete locking sealing, no repeated O-ring installation, alignment and inspection work, cutting single vessel assembly time by more than 40%. The product supports wet packaging standard export specifications, filled with protective preservation liquid inside the element, suitable for long-distance sea transportation without membrane layer dry cracking during transit. It is compatible with all common brackish water pretreatment equipment including multimedia filters, activated carbon filters, security filters and softeners, no special pretreatment parameter adjustment needed when replacing old membrane elements, lowering the technical threshold for factory operation and maintenance personnel.

Strong Anti-fouling Performance Adapt to Complex Raw Water:

For global projects with complex raw water quality such as rural well water, mining area brackish water and factory recycled wastewater, excellent anti-fouling capacity becomes an irreplaceable advantage of BW30-400/34i. The double guarantee of hydrophilic modified membrane surface and 34mil thick turbulent flow channel inhibits organic adhesion and inorganic mineral scaling simultaneously. When raw water contains high concentration of humic acid, microbial mucus, calcium bicarbonate and colloidal particles, narrow-channel ordinary membranes will form compact pollution cake within a short cycle, while this model’s continuous cross-flow turbulence scours pollutants in real time, delaying the formation of dense pollution layer. Even under raw water SDI value up to 5 (the upper limit of RO membrane feed water standard), it can maintain stable operation without rapid pressure difference rise. Many overseas water treatment contractors often face complaints about frequent membrane blockage from end customers; selecting BW30-400/34i effectively reduces post-sales technical support workload caused by raw water pollution, improving long-term cooperative stability with terminal factory clients.

Application Fields

Municipal Brackish Water Supply & Tap Water Purification:

Municipal brackish water supply projects are the largest application scenario of BW30-400/34i RO membrane around the world. Many coastal, inland arid and mining towns rely on high-salinity underground well water as domestic water source, raw water TDS usually ranges from 1000ppm to 8000ppm, requiring large-flow industrial RO systems to produce qualified drinking water. The model’s 11,000 GPD single-element water output and stable high salt rejection perfectly match large-scale municipal centralized water plants, which need continuous 24-hour unattended operation. The wide pH cleaning system simplifies daily maintenance of municipal water treatment stations with limited professional technical staff, and the anti-fouling wide flow channel adapts to seasonal raw water turbidity fluctuations caused by rainwater infiltration. Besides underground brackish water desalination, it is also widely used in municipal secondary tap water advanced purification, removing residual heavy metals, nitrate and soluble salts in pipeline tap water to improve domestic water taste and safety. Global local government water procurement projects, water treatment EPC contractors all take this membrane element as standard matching component for medium-salinity municipal water treatment lines.

Power Plant Boiler Makeup Water Demineralization:

Power plant boiler makeup water demineralization system is a high-standard industrial application field for BW30-400/34i. Thermal power, biomass power and waste incineration power plants require ultra-low conductivity boiler feed water to prevent boiler scaling and corrosion, reduce heat loss and extend boiler service life. Brackish underground water is the main raw water source for most inland power plants, and stable high rejection of this membrane ensures the TDS of RO permeate stays at low level, lowering the operation load of subsequent ion exchange mixed bed or EDI ultrapure water equipment. The iLEC interlocking end cap eliminates internal membrane shell leakage risk, avoiding sudden conductivity spike of boiler makeup water which may trigger equipment safety alarm. The wide pH cleaning range handles complex pollution generated by power plant raw water containing iron, manganese and silica, extending the cleaning cycle and reducing power plant shutdown maintenance frequency. For distributed small power stations and large thermal power group centralized water workshops, this 8040 standard membrane element can flexibly combine multiple sets to match different daily water production capacity demands.

Chemical & Petrochemical Industrial Wastewater Reuse:

Chemical and petrochemical factory brackish wastewater recycling projects put forward high anti-fouling requirements for RO membrane elements, which BW30-400/34i fully satisfies. Chemical production wastewater contains residual inorganic salts, organic solvents, catalyst colloids and mineral ions, after primary precipitation pretreatment, the intermediate water still belongs to medium-salinity brackish water, needing RO membrane to separate salts and realize wastewater zero-discharge reuse. The 34mil thick flow channel slows organic and inorganic mixed pollution accumulation, and 1-13 wide pH cleaning allows operators to deploy strong acid and strong alkali cleaning agents to thoroughly decompose chemical pollutants adsorbed on membrane surface. Stable permeate water quality can be recycled as production process water, cooling tower circulating water and workshop cleaning water, cutting factory raw water intake cost and meeting local industrial wastewater discharge environmental protection regulations. Global chemical park water treatment engineering companies frequently select this model for medium-salinity wastewater recovery lines, balancing anti-fouling performance and long-term operating economy.

Mining Area Well Water Desalination & Metallurgical Water Treatment:

Mining area brackish well water desalination and metallurgical circulating water treatment are typical harsh raw water application scenarios of BW30-400/34i. Mine underground well water contains high concentration of calcium, magnesium, sulfate and mineral colloids, raw water SDI value is higher than ordinary civilian well water, and metallurgical production circulating water accumulates metal ion scaling substances after long-term circulation. The thickened feed spacer and hydrophilic membrane surface jointly inhibit mineral scale and metal colloid adhesion, maintaining stable system pressure difference for long-term continuous mining production without frequent shutdown cleaning. The fiberglass integral shell resists slight corrosive ions in mine water, no shell aging cracking under 24-hour uninterrupted operation. The treated permeate can be used for mine underground production water, metallurgical workshop cooling water and staff domestic drinking water, solving the problem of insufficient fresh water supply in remote mining and metallurgical industrial zones without urban tap water pipeline coverage.

Electronic Factory Ultrapure Water Pre-treatment:

Electronic industry ultrapure water pre-desalination system demands consistent low TDS permeate as the front core process of EDI and ion exchange equipment. Semiconductor, PCB, lithium battery manufacturing factories adopt brackish underground water as raw water; unstable salt rejection of RO membrane will cause sharp fluctuation of ultrapure water resistivity, affecting product processing yield. BW30-400/34i’s 99.6% stable salt rejection provides steady low-salinity feed water for post-stage ultrapure water equipment, reducing the regeneration frequency of ion exchange resin and lowering EDI module power consumption. The anti-fouling structure avoids frequent membrane replacement during continuous electronic production, minimizing production line halt loss caused by water system maintenance. It is widely matched in medium and large electronic industrial park centralized water production systems worldwide, becoming a mainstream pre-desalination RO element for electronic ultrapure water projects.

FAQ

Q1: What do the numbers "34" and letter "i" stand for in BW30-400/34i? What are its core differences from ordinary 8040 brackish water RO membranes?

A1: Suffix 34 refers to the 34mil thick feed spacer, while conventional standard models only adopt 28mil narrow channels. The widened flow channels create continuous turbulent flow to slow sediment and colloid accumulation, extending the cleaning cycle by around twice.

Suffix i represents the iLEC interlocking end cap structure. It eliminates traditional separate O-ring sealing, leaving no assembly gaps between multiple membrane elements inside pressure vessels and preventing concentrated brine cross-leakage that contaminates permeate water.

Core differences: This model features a large 400 sq.ft membrane area of the same size, stable 99.6% salt rejection, full 1–13 pH tolerance for chemical cleaning, and hydrophilic modified anti-fouling membrane sheets. Common BW series membranes only deliver 99.0% salt rejection, support a narrow 2–11 cleaning pH range, adopt narrow channels prone to fouling, and use split end caps susceptible to leakage.

Q2: What water quality is BW30-400/34i compatible with? What are the limits of raw water TDS and SDI? What scenarios are not suitable for it?

A2: Applicable raw water: Medium-salinity brackish water with salinity ≤10,000 ppm, including well water, municipal slightly saline water and secondary industrial reclaimed water. Its standard test condition is 2000 ppm NaCl solution.

Inlet water indicators: SDI ≤5; short-term maximum allowable SDI is 5, while long-term stable operation requires pretreatment to control SDI below 3.

Inapplicable scenarios: Seawater (TDS exceeding 10,000 ppm), untreated wastewater with heavy oil and sludge, raw water with persistent strong acid or alkali (the 1–13 pH range only applies to short-term chemical cleaning instead of long-term feed water).

Q3: What operation and maintenance costs can the combination of 34mil wide feed spacer and iLEC interlocking end caps cut down for water treatment systems?

A3: Four types of costs are reduced simultaneously:

Energy cost: Wider flow channels reduce internal flow resistance, allowing high-pressure pumps to operate at relatively low pressure and cutting annual power consumption by 12%–18% under equivalent water production volume.

Chemical cost: The anti-fouling structure extends the chemical cleaning cycle from 1–2 months to 3–4 months, drastically lowering the purchase volume of acid and alkali cleaning agents.

Consumable replacement cost: Wide pH cleaning tolerance prevents irreversible membrane damage caused by improper cleaning. Its average service life reaches 3–5 years, one year longer than conventional brackish RO membranes, reducing annual procurement expenses for membrane replacement.

Labor and downtime cost: Interlocking end caps simplify installation without repeated O-ring fitting, alignment and inspection, cutting single pressure vessel assembly time by over 40% and greatly reducing after-sales maintenance workload caused by leakage failures.

Q4: What practical benefits does the 1–13 full-range pH cleaning capacity bring? What drawbacks do ordinary membranes with narrow pH tolerance have?

A4: Advantages of wide pH tolerance: Alkaline cleaning solution at pH 12–13 can decompose organic slime and oil stains, while acidic cleaning solution at pH 1–2 dissolves calcium carbonate, silica scale and sulfate deposits. All types of composite fouling can be thoroughly removed, and membrane performance can be restored to factory standards after each cleaning.

Drawbacks of ordinary membranes: They only withstand a narrow pH range of 2–11, making it impossible to use concentrated strong acid and alkali cleaners to fully remove composite scale. Long-term exposure to strong acid and alkali will trigger membrane layer hydrolysis and pore expansion, leading to permanent irreversible decline in salt rejection and premature scrapping of membrane elements.

Q5: Can BW30-400/34i directly replace old membranes inside existing 8-inch pressure vessels? What precautions should be taken during replacement?

A5: Compatibility: It adopts standard 8040 dimensions and fits all mainstream 8-inch pressure vessels on the market. No customized pressure vessels, adapters or pipeline modification are required for new system construction or old equipment renovation.

Key replacement notes:

① Thoroughly clean pipelines and pressure vessels before replacing old equipment to avoid existing dirt directly attaching to new membranes.

② No special adjustment of pretreatment equipment parameters is needed; multimedia filters, water softeners and security filters work normally as matched accessories.

③ No extra O-rings are required for interlocking end caps. Simply align two membrane elements and push to complete locking, as extra sealing rings may cause blockages.

④ Products are delivered as wet membranes sealed with protective preservation liquid, suitable for long-distance sea transportation without membrane layer cracking. Fully flush the preservative liquid before official water production after arrival.

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