Water with a higher salt concentration than typical freshwater can create different requirements for a reverse osmosis system. Groundwater, surface water, municipal supplies, and certain industrial streams may contain dissolved salts that make conventional water treatment insufficient. In these cases, membrane selection needs to account for the actual feed-water conditions rather than relying on a general RO configuration.
A brackish water membrane is designed for this type of desalination application. At Runmo, we develop membrane products for different water qualities, including our BW series for brackish-water treatment.
What Is Brackish Water?
Brackish water generally refers to water that contains more dissolved salts than freshwater but less than typical seawater. Its composition can vary considerably depending on its source, so there is no single water profile that represents every brackish-water application.
For membrane system designers, the important factors are measurable water-quality parameters. TDS, temperature, pH, turbidity, organic content, hardness, and other contaminants can affect membrane selection and system operation.
This is why we recommend starting with a water analysis when selecting a RO membrane. The correct product depends not only on salinity but also on the required permeate flow, target rejection, and operating pressure. Our technical team can use these parameters to recommend a suitable membrane configuration.
How Does a Brackish-Water RO Membrane Work?
Reverse osmosis uses pressure to drive feed water through a semipermeable membrane. Water molecules can pass through the membrane, while dissolved salts and other substances are retained to a significant extent.
A brackish water membrane is therefore not simply a filter for visible particles. Its role is to support dissolved-solids separation within a RO system. Pretreatment remains important because suspended solids, microorganisms, organic matter, and other contaminants can affect membrane performance.
For this reason, membrane selection and pretreatment should be considered together. A membrane that is technically suitable for the feed-water salinity may still require an appropriate upstream treatment process to maintain stable operation.
Where Are These Membranes Commonly Used?
Brackish-water RO is relevant to a wide range of water sources and industrial processes. The BW series is suitable for desalination of surface water, groundwater, tap water, and municipal water with salt content below 10,000 ppm, while the published maximum feed-water TDS for operation is 5,000 ppm.
This makes the series applicable to several practical scenarios:
Industrial Pure Water
Industrial facilities may need treated water for manufacturing processes, equipment, or downstream purification. Our BW series is designed for industrial pure-water applications at different scales, where dissolved salts need to be reduced before the water enters subsequent processes.
Power Plant Boiler Feed Water
Boiler systems require controlled water quality because dissolved substances can create operational problems. Our BW membranes can be used for boiler feed-water treatment as part of an appropriately designed purification system.
High-Concentration Saline Wastewater
Some industrial wastewater streams contain substantial dissolved salts. Our BW series can also be applied to brackish-water scenarios involving high-concentration saline wastewater, although the actual membrane configuration should be determined according to the specific wastewater characteristics.
Beverage Water Production
Water quality is an important part of beverage manufacturing. Beverage water manufacturing is another application for the BW series, subject to the relevant feed-water and process requirements.
What Should Buyers Check Before Choosing a Membrane?
Choosing a membrane based only on the phrase “brackish water” can be misleading. Two water sources with similar TDS levels may have very different temperatures, organic loads, hardness, or fouling potential.
At Runmo, we recommend evaluating the complete feed-water profile before selecting a membrane. Our selection process considers TDS, temperature, pH, required permeate flow, target rejection, and operating pressure. Where available, a water analysis report gives our technical team a more reliable basis for product recommendation.
Pretreatment should also be evaluated at the same time. Depending on the source water, the system may need processes that control suspended solids, turbidity, organics, or other substances before the RO stage.
What Makes the Runmo BW Series Different?
Our BW series uses an aromatic polyamide composite membrane element specifically designed for brackish-water desalination. Runmo states that the series combines high water production with good desalination performance and provides strong removal performance for soluble salts, TOC, and SiO₂. The product is also identified as particularly suitable for highly purified water production in electronics and power-related applications.
We also offer a FR series surface treatment for the membrane. This treatment changes the surface charge and smoothness while increasing surface hydrophilicity. The intended result is reduced contamination from pollutants and microorganisms on the membrane surface, helping reduce membrane-component fouling and support longer service life.
These characteristics make the BW series a practical option to evaluate when a project requires RO desalination for moderately saline water rather than seawater.
Selecting the Right Solution for Your System
There is no universal membrane choice for every brackish-water project. Feed-water quality, required production capacity, rejection requirements, system pressure, pretreatment, and operating conditions all influence the final selection.
Our broader membrane portfolio includes BW membranes alongside ULP, SW, NF, PAN UF, and PVDF UF products. This allows us to approach membrane selection according to the water-treatment requirement rather than forcing every application into the same membrane category.
As a direct manufacturer, we maintain vertically integrated production from raw membrane-material preparation through finished product assembly. We also provide customized solutions, including specific dimensions, housing designs, and performance characteristics, as well as OEM/ODM services for system integrators and distributors.
Work With Runmo on Your Brackish-Water Project
At Runmo, we are Suzhou Runmo Water Treatment Technology Co., Ltd., a manufacturer specializing in reverse osmosis membranes, ultrafiltration membranes, and polymer membrane technology. We operate an independent R&D system and automated production lines, with annual production capacity of more than 800,000 membrane products and more than 40 patents. We provide products and technical support to more than 60 countries.
If you are sourcing a brackish water membrane for industrial water production, boiler feed water, saline wastewater, or another RO application, send us your water analysis and project requirements. We can help evaluate the appropriate BW membrane and develop a solution around your actual operating conditions.
