High Boron Leakage In SWRO: Fix Without Secondary RO

High Boron Leakage In SWRO: Fix Without Secondary RO

Severe boron leakage is a common performance defect of traditional imported SWRO membranes including SW30 and SWC series, which forces many offshore and island projects to add extra secondary RO to meet drinking water boron limits and greatly raises overall investment and energy consumption. This article analyzes the inherent low boron interception defects of mainstream imported seawater membranes, elaborates the long-term boron interception mechanism of our self-developed TSE high boron rejection membrane, and puts forward targeted one-stage replacement schemes without adding secondary reverse osmosis, matching the search demands of island water plants and offshore platform clients.

Overview of Industrial Pain Points

Natural seawater contains high concentration of neutral boric acid molecules, and conventional imported SW30, SWC seawater RO membranes only rely on basic polyamide interception without targeted boron capture functional groups, resulting in persistent boron leakage in single-stage operation. Most project owners adopt two-stage RO process to reduce effluent boron content, which brings extra high-pressure equipment, pipeline transformation and long-term power loss.

Island desalination stations and offshore oil & gas platforms have limited space and tight power supply budget; building an independent secondary RO system will occupy valuable equipment area and increase daily operation cost. Many operators are looking for a single-stage membrane upgrading solution to eliminate boron excess fundamentally without extra system expansion.

Our self-developed TSE high boron rejection SWRO membrane optimizes molecular structure and adds nano boron-trapping functional layers during film forming, realizing stable high boron interception in single-stage seawater desalination, which completely avoids the construction cost and energy consumption of secondary RO.

Root Cause of Boron Overlimit: Inherent Defects of Imported SW30 & SWC Membranes

Ordinary imported SW30, SWC polyamide seawater membranes adopt conventional low-crosslink separation layer formula, only intercept charged salt ions through charge repulsion, but neutral boric acid carries no electric charge and can freely pass through loose membrane molecular gaps, causing serious boron leakage.

The active layer of imported SW series membranes has no dedicated boron capture functional groups. Under variable seawater temperature and pH fluctuation, boron rejection rate drops sharply, and stable effluent boron index cannot be guaranteed in single-stage operation.

Narrow 28mil feed spacer of traditional SW membranes is easy to form boron salt crystal scaling on the membrane surface. Boron crystal deposits will further widen membrane micro-pores, accelerate progressive boron leakage and shorten service life of membrane elements.

Even with advanced pretreatment and pH adjustment, the maximum boron rejection of original SW30/SWC membranes cannot reach the drinking water standard; the only traditional solution is to configure complete secondary RO for secondary interception.

Long-Term Boron Interception Mechanism of TSE High Boron Rejection SWRO Membrane

Our TSE membrane adopts ultra-high cross-linking polyamide substrate as the base separation layer, narrowing molecular gaps to block the free penetration channel of neutral boric acid at physical level.

Nano boron-trapping functional groups are evenly embedded into the molecular chain of the active layer, which can generate weak coordination bonding with neutral boric acid molecules to lock boron ions on the membrane surface and avoid permeation into produced water.

Upgraded wide 31mil trapezoidal spacer strengthens cross-flow scouring force, effectively wash away boron salt crystal precursors on membrane surface, suppress scaling accumulation and maintain long-term stable boron interception efficiency.

The integrated material & structural design of TSE membrane balances high boron rejection, high salt rejection and anti-fouling performance, realizing qualified boron index under single-stage SWRO without supporting secondary RO equipment.

Targeted Replacement Matching Scheme for Different Application Scenarios

Scenario 1: Island Drinking Water Desalination Project (Original SW30 Membrane)

Set daily automatic low-flow shutdown flushing procedure to discharge concentrated brine containing high-concentration boron salt, avoid long-time stagnation and crystal scaling on the surface of TSE membrane.

Adopt low-concentration compatible alkaline cleaning agent for periodic CIP; the wide pH tolerance window of TSE membrane will not damage internal boron-trapping functional layers during pollutant stripping.

FAQs

Q1: After replacing original SW30 membrane with TSE high boron rejection membrane, can single-stage SWRO meet drinking water boron standard without installing secondary RO?

A1: Yes. TSE membrane adopts ultra-high cross-link polyamide substrate with embedded nano boron-trapping functional groups, matching wide anti-scaling spacer. Under standard seawater operating parameters, single-stage boron rejection can reach over 93%, effluent boron index fully meets drinking water requirements, completely eliminating the need for secondary RO supporting facilities.

Q2: Why do imported SWC membranes suffer sharp boron rejection drop when seawater temperature rises?

A2: SWC series low-crosslink active layer has no targeted boron capture groups. High temperature accelerates the movement of neutral boric acid molecules, enabling more boron to pass through loose molecular gaps, resulting in obvious boron leakage surge. TSE’s dual interception mechanism can resist temperature fluctuation interference effectively.

Q3: Can TSE membrane completely replace two-stage RO process for offshore platform projects with strict boron limits?

A3: It can fully replace two-stage RO under standard seawater quality. Only replace all original SW series elements with TSE membrane, cooperate with pH adjustment and regular flushing maintenance, and no extra secondary RO equipment is required to satisfy strict boron discharge standards, saving platform space and power consumption.

Q4: Will boron salt scaling accelerate the performance attenuation of TSE high boron rejection membrane?

A4: No. TSE equips upgraded 31mil wide trapezoidal spacer to enhance cross-flow scouring force, greatly reduce boron crystal adhesion probability. As long as regular flushing and pH adjustment specifications are followed, boron salt scaling will not cause permanent damage to the boron-trapping functional layer.

Q5: Is mixed installation of original SW30 membrane and TSE membrane allowed in one pressure vessel?

A5: Mixed assembly is not recommended. SW30 and TSE differ greatly in molecular cross-link density, boron interception structure and spacer width, leading to uneven flow distribution and inconsistent boron leakage among elements, which fails to stabilize overall effluent boron index. All elements inside a single pressure vessel should adopt unified TSE membrane.

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