RO Membrane Solution For Mariculture Seawater Circulation

RO Membrane Solution For Mariculture Seawater Circulation

Mariculture recirculating systems have rigid water quality standards for low boron control. Conventional imported standard seawater RO membranes possess weak boron interception capacity, and excessive residual boron in permeate will hinder the development and reproduction of fish, shrimp, shellfish and coral larvae, raising breeding loss and operation cost significantly. This paper diggs deep into boron pollution pain points in aquaculture, systematically analyzes the inherent boron rejection defects of common imported SW membranes, and elaborates the molecular modification separation mechanism of TSE high boron rejection RO series. Product comparison is conducted from interception performance, working condition adaptability and operation cost. Matching complete operation specifications including standardized pretreatment, parameter control and CIP cleaning are provided for typical scenarios such as factory recirculating water, indoor offshore seedling raising and coral cultivation. Frequent on-site operation mistakes and targeted avoidance schemes are summarized, delivering a full set of RO solution with stable low boron output and long-term anti-fouling performance for large-scale mariculture circulation projects.

Overview of Mariculture Industry Pain Points

1. Boric acid exists as uncharged neutral molecules under conventional seawater pH 7.0–8.3; common SW membranes rely only on salt sieving structure and cannot effectively intercept tiny neutral boron molecules, with single-pass boron rejection merely 75%–85%.

2. Permeate boron content exceeds 1 mg/L, far beyond the breeding threshold of 0.2–0.6 mg/L for rare fry and coral culture, requiring secondary RO polishing or heavy chemical boron removal, greatly increasing equipment investment and chemical consumption.

3. To lower boron residue, users are forced to reduce system recovery rate, leading to massive seawater raw water waste and higher energy consumption per ton of water.

4. Conventional imported SW membranes adopt narrow pH tolerance active layer, prone to organic biofouling and algae contamination in aquaculture water, with frequent CIP cleaning and short service life.

Our self-developed TSE high boron rejection series RO membrane targets the above bottlenecks, specially modified for mariculture closed circulation water, balancing ultra-high boron interception, high salt rejection and biological anti-fouling capacity to resolve the long-standing boron excess trouble of breeding water.

Scientific Separation Mechanism of TSE High Boron Rejection Membrane

Defect Analysis of Conventional Imported SW Membrane & TSE Membrane Core Advantages

1. Boron Removal Shortcomings of Ordinary Imported Seawater RO Membrane

Standard imported SW series membranes are developed for general seawater desalination projects, without targeted modification for neutral boron molecules, showing obvious performance defects under mariculture circulating water:

Single-pass boron rejection only 75%–85%; when seawater feed boron is 4.5mg/L, permeate boron reaches 0.68–1.13mg/L, exceeding the safe standard for juvenile fish and coral breeding.

To reduce boron residue, the system needs to raise pH above 9.0 before filtration, extra alkali dosing increases water chemical imbalance risk, disturbing breeding water alkalinity stability.

Narrow cleaning pH window 2–11; high-pH alkaline cleaning for algae and bio-slime will erode thin active layer, causing continuous salt passage rise and performance attenuation after repeated cleaning.

Strong organic adsorption tendency, residual bait and metabolic pollutants form compact biofilm rapidly, transmembrane pressure difference rises 0.15MPa within 2–4 months, requiring frequent offline cleaning.

2. Comprehensive Performance Advantages of TSE High Boron Rejection Membrane TSE

Compared with conventional imported seawater RO membranes, TSE series achieves all-round performance upgrade for mariculture circulating water, core advantages sorted as below:

Typical Application Scenarios of TSE High Boron Rejection Membrane TSE

Factory intensive seawater circulating aquaculture: Large-scale prawn, sea cucumber, abalone breeding, reduce boron accumulation in circulating water, cut fry mortality caused by long-term boron exposure.

Indoor marine seedling raising workshop: Larval fish, shellfish artificial propagation with strict boron control threshold, single-stage RO reaches qualified low boron water without secondary polishing system.

Coral and marine ornamental organism culture: Corals are highly sensitive to boron excess, TSE membrane maintains permeate boron within 0.2–0.5mg/L to guarantee normal calcification and growth of reef organisms.

Offshore cage supporting water regulation system: Raw seawater pre-desalination before entering cages, control water boron and salinity to stabilize offshore breeding environment.

Closed zero-discharge mariculture project: Long-term circulating reuse of seawater, restrain continuous boron enrichment, reduce wastewater discharge and environmental pollution risk of high-boron concentrated water.

Complete Operation & Maintenance Standard for Mariculture RO System

1. Supporting Pretreatment Configuration

Breeding seawater contains residual bait, algae, suspended sediment and organic colloids; standardized pretreatment is the premise to extend TSE membrane service life:

2. Daily Operation Parameter Control

System recovery rate: Mariculture circulating water controlled at 40%–50%, over-high recovery aggravates boron concentration polarization and biofouling.

Operating temperature: Optimum 22–30℃, temperature higher than 35℃ accelerates organic pollutant adhesion.

Running pH: Maintain 7.0–8.3 for conventional operation; adjust pH to 10.5–11.5 only during alkaline CIP cleaning.

Pressure management: Soft start and soft shutdown are mandatory to avoid water hammer impact on membrane elements; stable operating pressure within rated range of seawater RO membrane.

Monitoring frequency: Record permeate boron, salinity, feed pressure and segment differential pressure every 4 hours; start CIP cleaning when normalized flux drops 10% or differential pressure rises 15%.

3. Standard CIP Cleaning Process & Operation Mistake Avoidance

Standard Alkaline-First-Then-Acid Cleaning Sequence

Step 1：Alkaline cleaning (target algae, bio-slime, residual organic bait): Prepare NaOH + biological surfactant solution, pH 10.5–11.5, circulation 90–120min, temperature 25–30℃.

Step 2：Flush thoroughly with qualified seawater until neutral pH.

Step 3：Acid cleaning (target inorganic scaling and boron sediment): Citric acid cleaning liquid pH 2.5–3.5, circulation 60–90min.

Step 4：Post-cleaning flushing, verify flux and boron rejection recovery before formal operation.

Fatal Operation Mistakes

Reverse cleaning sequence (acid first then alkali): Organic residual bait denatures and solidifies into irreversible fouling, boron interception performance drops permanently.

Over-temperature cleaning above 35℃: Accelerate membrane aging, shorten service life.

Insufficient flushing between alkali and acid steps: Residual acid-base mixing causes chemical secondary damage to active layer.

Blind frequent cleaning without threshold judgment: Continuous chemical erosion weakens boron selective functional groups.

Adopt over-limit pH cleaning for ordinary imported SW membranes: Narrow pH window leads to active layer thinning and permanent boron rejection attenuation.

FAQs

Q1: Why ordinary imported seawater RO membranes cannot meet mariculture low boron water demand?

Q2: Does TSE high boron rejection membrane need secondary RO polishing for mariculture circulating water?

Q3: Can TSE membrane directly replace original imported SW membrane without equipment modification in aquaculture projects?

Q4: What is the core advantage of TSE membrane 1–13 full pH cleaning tolerance for aquaculture water rich in algae?

Q5: Will long-term circulating boron accumulation damage TSE high boron rejection membrane?