Membrane Surface: Maximum Temperature 45°C

Q: What causes fouling on RO membrane surfaces?

Fouling results from scaling (mineral deposits like calcium carbonate), organic adsorption (humic acids, proteins), biological growth (biofilms), and colloidal particle accumulation, all reducing flux and increasing pressure requirements.

Q: How is membrane surface performance tested?

Performance is validated through standardized tests measuring salt rejection percentage, normalized water flux, pressure drop, and integrity testing using conductivity meters, flow meters, and pressure gauges under controlled conditions.

Component Specifications

Definition

The membrane surface is the critical functional interface in a reverse osmosis (RO) membrane element. It is a thin, dense polyamide active layer formed via interfacial polymerization on a porous polysulfone support. This surface governs the separation performance by applying size exclusion and solution-diffusion mechanisms under high pressure, typically 15-85 bar, allowing water permeation while rejecting over 99% of monovalent ions, organic molecules, and particulates.

Working Principle

Operates on the solution-diffusion model under applied transmembrane pressure. Water molecules dissolve into the polyamide matrix, diffuse through the dense polymer structure due to a concentration gradient, and desorb on the permeate side. Dissolved ions and larger solutes are excluded based on size and charge repulsion, with separation efficiency enhanced by the membrane's negative surface charge.

Materials

Thin-film composite (TFC) polyamide active layer (typically aromatic polyamide from m-phenylenediamine and trimesoyl chloride), supported by microporous polysulfone layer (40-150 μm thick) and non-woven polyester fabric backing (120-200 μm thick).

Technical Parameters

Parameter	Typical range	Notes & selection driver
PH Range	2-11 (continuous), 1-12 (cleaning)
Water Flux	25-45 L/m²·h @ 25°C, 15.5 bar
Salt Rejection	>99.7% (NaCl)
Chlorine Tolerance	<0.1 ppm
Maximum Temperature	45°C
Maximum Operating Pressure	41 bar (600 psi)

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 11270, DIN 20043

Parent Products

This component is used in the following industrial products

Reverse Osmosis Membrane

A semi-permeable membrane used in reverse osmosis systems to remove dissolved solids, ions, and contaminants from water by applying pressure to overcome osmotic pressure.

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Engineering Analysis

Risks & Mitigation

Surface abrasion from particulate matter
Chemical degradation from oxidants (chlorine)
Biofouling reducing efficiency
Compaction under excessive pressure

FMEA Triads

Trigger: Chlorine exposure exceeding 0.1 ppm
Failure: Oxidative degradation of polyamide chains, leading to loss of salt rejection capability
Mitigation: Implement dechlorination pretreatment using activated carbon filters or sodium bisulfite injection; install ORP monitoring

Trigger: Inadequate pretreatment allowing scaling
Failure: Mineral scale (CaCO₃, CaSO₄) deposition on surface, causing flux decline and increased energy consumption
Mitigation: Maintain LSI < 0 with antiscalant dosing; implement regular CIP with acid cleaners (pH 2-3)

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Salt rejection tolerance ±0.2% from rated value; flux tolerance ±15% under standard test conditions

Test Method

ASTM D4194 for salt rejection; ASTM D6908 for flux normalization; ANSI/NSF 58 for material safety

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

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Inspection readiness

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Manufacturers of Membrane Surface

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Frequently Asked Questions

What causes fouling on RO membrane surfaces?