Overview
Both Ultrafiltration (UF) membranes and Membrane Bioreactor (MBR) membranes are hollow fibre filtration technologies manufactured from PVDF or similar polymers. They look similar and are both supplied by companies like Grafil. However, they are used in fundamentally different parts of the water treatment process and have different design priorities.
What Is a UF Membrane?
A UF membrane is a pressure-driven separation membrane with pore sizes typically between 0.01 and 0.1 microns. It physically removes suspended solids, colloids, bacteria, and large viruses from water. UF is used as a standalone polishing step — usually on pre-treated surface water, well water, or secondary treated wastewater — to produce high-quality permeate for reuse or further treatment.
What Is an MBR Membrane?
An MBR membrane is specifically designed to be submerged directly inside a biological treatment tank (aeration basin) alongside activated sludge. It replaces the conventional secondary clarifier. The membrane acts as both the biofilm support and the solid-liquid separator. MBR pore sizes are similar to UF (0.03–0.4 microns) but the modules are engineered to handle continuous submersion in high mixed liquor suspended solids (MLSS) concentrations of 8,000–15,000 mg/L.
Side-by-Side Comparison
| Parameter | UF Membrane | MBR Membrane |
|---|---|---|
| Placement in process | Post secondary treatment | Inside biological tank |
| Feed water quality | Pre-treated, low TSS | Raw mixed liquor, high MLSS |
| Operation | Pressurised (outside-in) | Submerged, vacuum-driven |
| Flux (LMH) | 40–80 LMH typical | 10–25 LMH (more fouling) |
| Replaces | Sand filters or polish polishing | Secondary clarifier |
| Footprint benefit | Moderate | Very compact STP plant |
| Effluent quality | Very high (NTU < 0.1) | Very high + low BOD/COD |
When to Use UF vs MBR
Choose UF membrane when:
- You need to polish secondary treated or surface water
- Your incoming feed is already relatively clean (TSS < 50 mg/L)
- You want a high-quality permeate for RO pre-treatment
- You have existing secondary clarifiers and just want a polishing upgrade
Choose MBR membrane when:
- You are building a new STP or ETP from scratch
- Space is constrained and you cannot accommodate a clarifier
- Your effluent standards demand BOD < 10 mg/L and TSS < 10 mg/L
- You need compact, automated, and odour-free wastewater treatment
Grafil UF and MBR Membranes from QuaSys
QuaSys Inc. is an authorized dealer for Grafil UF Membranes and Grafil MBR Membranes in India. Our technical team can help you select the right module configuration for your flow rate, space, and effluent targets.
Call us at +91 11 29531287 or send an enquiry.
