RO membrane brand comparison: how to choose among eight brands

1. The eight brands at a glance

The table follows brand background — main series — typical duty — official channel. The “Typical duty” column follows the application categories published by each vendor in its own materials rather than our own summary. Phone numbers change, so none are listed; use the manufacturer's website for technical support or samples.

"In our library" is the number of models held here, not the vendor's full catalogue, but it covers the usual selection range. Qualifications, authorisations and contacts follow each vendor's current website.

The Vontron row reproduces the seven categories under “Application” on the vendor's own English site (en.vontron.com/Application/7.html: seawater desalination, zero discharge of industrial wastewater, municipal water supply, urban wastewater reuse, specialty separation, electronic ultrapure water, food and beverage), with no project-type filtering applied here. Other rows will be aligned to their own vendor categories in turn.

2. Seawater desalination

The key property of a seawater element is not rejection but pressure tolerance and flux stability. At 35000 mg/L feed and 45% recovery the concentrate approaches 2× concentration, osmotic pressure exceeds 50 bar, and the membrane runs above 60 bar for years.

Look at: maximum pressure drop per element, allowable feed pressure, temperature ceiling, and the flux-decline curve at high salinity. Common models in this class include Ovay OV-SW-8040-HR/XHR, Hydranautics SWC6 series, DuPont SW30HRLE/XHR, Toray TM820 series and LG SW 400 GR.

Note: seawater recovery is usually limited to 40–45% by osmotic pressure and scaling. Do not apply brackish "high recovery" thinking here.

3. Brackish water and tap water

This is the segment with the densest choice of models. At 500–5000 mg/L salinity and SDI below 3, low-energy and ultra-low-pressure series are the mainstream choice: Ovay OV-U-8040-440 / OV-X-8040 440, Hydranautics ESPA2-LD, DuPont BW30HRLE-440, Toray SUL-G20, LG BW 400 ES, CSM RE8040-UL and Vontron ULP32.

The usual logic: where electricity is expensive, take low energy first; where water is cold or winters are long, take higher flux; where feed salinity is above 3000 mg/L, take higher rejection rather than saving pressure at the cost of permeate quality.

4. Wastewater reuse and fouling resistance

Reuse water risks organics, micro-organisms and colloids more than salt. A fouling-resistant element (hydrophilic surface modification, wider feed spacer) lengthens the cleaning interval but does not replace pretreatment.

Rule of thumb: municipal reuse design flux is usually held at 12–17 LMH, 20–30% below tap water; prefer 34 mil spacers or LD models to limit the pressure rise caused by fouling. Ovay OV-FR-8040 400, Hydranautics LFC3-LD, DuPont BW30FR/Fortilife, Toray TLF, LG BW 400 AFR, CSM RE8040-BLF and Vontron FR22 all sit in this class.

5. Ultrapure and boiler make-up water

Electronics, power and pharmaceutical ultrapure systems are usually "RO + EDI + polishing mixed bed". The RO stage cares about rejection stability, TOC leaching and boron/silica removal. Ovay OP5-30 and OP5-10 sit in the high-rejection tier; Toray, DuPont and Hydranautics CPA series also cover this duty — confirm applicability against each vendor's datasheet.

Note that TOC and boron removal do not scale linearly with rejection, so look at the vendor's specific data rather than at the 99.7% headline figure.

6. How to compare

1. Fix the conditions. Same water analysis, same permeate flow, same recovery, same temperature — otherwise the comparison means nothing.
2. Align the array. 400 and 440 ft² elements differ in area, so element count and array change; let the software solve it again instead of converting by hand.
3. Look at four results. Feed pressure, specific energy, concentrate saturation, and lead/tail flux distribution.
4. Look at the cleaning and replacement rhythm. Cleaning interval, replacement interval and model availability usually need confirming earlier than any single figure.