Selecting the correct membrane technology determines effluent quality, energy consumption, concentrate management requirements, and the economic viability of the project.
Removes suspended solids, colloids, bacteria, viruses, and macromolecules by size exclusion alone. Operating pressure 0.5–3 bar. Does not remove dissolved salts or small organic molecules. Used as RO pretreatment, MBR membranes, or standalone polishing. SDI reduction to <3 reliably. See our UF membrane equipment.
A “loose RO” membrane that rejects divalent ions (Ca² +, Mg² +, SO&sub4;² −) at 90–98% while passing monovalent ions (Na +, Cl −) at 10–50%. Removes natural organic matter (NOM), colour, hardness, and emerging contaminants. Operating pressure 5–15 bar. Energy cost intermediate between UF and RO.
Non-porous semi-permeable membrane rejecting >95% of all dissolved species including monovalent salts, by solution-diffusion mechanism. Operating pressure 8–80 bar depending on feed salinity. Produces high-purity permeate and a concentrated brine requiring management. See our RO skid equipment and RO protection strategies.
UF removes bacteria and colloids for tertiary filtration. NF softens water and removes colour. RO produces near-pure water for reuse or boiler feed. We pilot test to validate flux, fouling rates, and cleaning frequency for your specific application.
| Parameter | UF | NF | RO |
|---|---|---|---|
| Pore / effective size | 0.01–0.1 µm | 0.001–0.01 µm | <0.001 µm (non-porous) |
| Operating pressure | 0.5–3 bar | 5–15 bar | 8–80 bar |
| Monovalent salt rejection | <5% | 10–50% | >95% |
| Divalent salt rejection | <5% | 90–98% | >98% |
| NOM / colour removal | Partial | Excellent | Excellent |
| Bacteria / virus removal | 6 log / 4 log | Complete | Complete |
| PFAS removal | Poor | Moderate (long-chain) | Good (>90% for PFOS/PFOA) |
| Silica removal | None | Partial | >95% |
| Energy use (kWh/m³) | 0.05–0.3 | 0.3–1.0 | 0.5–15 (seawater) |
| Concentrate / brine generation | Minimal (backwash only) | 15–25% of feed | 20–50% of feed |
| Scaling propensity | Low | Moderate | High (requires antiscalant) |
| Fouling sensitivity | Moderate (backwashable) | Moderate | High (irreversible fouling risk) |
| Capital cost (relative) | Low | Medium | High |
| Pretreatment requirement | SDI <5 | SDI <4 | SDI <3 (UF preferred) |
UF ahead of RO reduces the SDI reliably to <3, protecting RO membranes from colloidal fouling and extending RO element life. Standard pretreatment for desalination plants and high-purity industrial RO systems.
Full demineralisation to conductivity <10 µS/cm required for boiler feed, pharmaceutical WFI, and semiconductor process water. RO is the entry point; followed by EDI or ion exchange for highest purity.
NF removes hardness (Ca, Mg), sulphate, NOM, and colour while retaining the majority of monovalent minerals, producing softer, aesthetically improved drinking water at lower energy than RO.
Feed TDS 1,000–10,000 mg/L. RO at 8–20 bar achieves permeate TDS <200 mg/L. Used for industrial process water supply from brackish groundwater or blowdown recovery. See desalination systems.
NF concentrates dairy CIP streams, allowing caustic and acid recovery and producing a permeate suitable for reuse. Reduces effluent volume and chemical procurement costs. See dairy wastewater treatment.
UF membranes are integral to MBR systems, providing the separation function that replaces secondary clarification. See the MBR vs SBR vs MBBR comparison for context.
Reverse osmosis systems for brackish water, seawater, and industrial applications.
View RO SkidsUltrafiltration systems for pretreatment, MBR, and standalone polishing.
View UF SystemsCalculate membrane area, flux, recovery, and TMP for your feed water quality.
Use CalculatorPretreatment design, antiscalant selection, and cleaning protocols to protect RO membranes.
RO ProtectionOur process engineers will evaluate your application and recommend the optimal solution for your flowrate, quality targets, and budget.
Our expertise spans multiple industries with sector-specific water treatment solutions.