Product Introduction

Ultrafiltration (UF) is a membrane separation technology used to purify, separate or concentrate a solution. UF lies between microfiltration and nanofiltration, and there is no clear dividing line between the three. Ultrafiltration membrane pore sizes generally fall in the range of 0.05 µm down to about 1 nm, with an operating pressure of 0.1–0.5 MPa. UF is mainly used to reject suspended solids, colloids, particles, bacteria and viruses — in other words, macromolecular substances. By membrane material, UF membranes are classified as organic or inorganic; by configuration, as flat-sheet, tubular, capillary, hollow-fibre or porous. Most domestic UF water purifiers use hollow-fibre membranes.

How Ultrafiltration Works

Ultrafiltration is one of the pressure-driven membrane separation technologies, and its purpose is to separate macromolecules from small molecules. The hollow-fibre UF module offers a high packing density per unit volume and therefore a small footprint. During ultrafiltration the feed solution flows across the membrane surface under pressure: the solvent (water) and small-molecule solutes that are smaller than the membrane pores pass through the membrane and become the purified liquid (permeate), while solutes and solute aggregates that are larger than the pores are retained and discharged with the flow as the concentrate.

UF is a dynamic filtration process — separation takes place while the water is flowing. Solute is deposited only to a limited extent on the membrane surface; the UF flux decays to a certain level and then tends to equilibrate, and it can be restored by cleaning.

UF is a pressurised membrane separation technology. Under a certain pressure, small-molecule solutes and the solvent are forced through a specially made membrane of a defined pore size, while macromolecular solutes cannot pass through and remain on one side of the membrane, so that the macromolecular substances are partly purified.

Key Features

• High-precision hollow-fibre membrane filtration that removes suspended solids, colloids, particles, bacteria and viruses.
• High packing density per unit volume, giving a compact system with a small footprint.
• Dynamic (cross-flow) filtration: solute deposits only to a limited extent on the membrane surface, so flux stays stable.
• Flux lost to fouling can be fully restored by cleaning, giving a long membrane service life.
• No chemical addition required for the separation itself; low operating cost.
• Stable product-water quality, with a high degree of automation.
• Complete pre-treatment (mechanical filter, carbon filter, ion exchange and security filter) protects the UF membranes.

Technical Specifications

Process Flow

Raw water is drawn from the raw-water tank by the raw-water pump and passes through the mechanical (multi-media) filter and the activated-carbon filter, which remove suspended solids, turbidity, colour, odour and residual chlorine. The water then passes through ion exchange and into the storage tank before being fed to the UF main unit, where the hollow-fibre membranes retain colloids, particles, bacteria and viruses. A security filter provides final protection, and the purified water is delivered to the point of use.

Product Details

Applications

• Production of drinking water and municipal water supply
• Removal of bacteria, viruses, colloids and turbidity from surface water and groundwater
• Pre-treatment ahead of reverse osmosis and EDI systems
• Process water for the food & beverage, pharmaceutical and electronics industries
• Recycling and reuse of industrial wastewater and rinse water
• Separation, concentration and purification in the chemical and dye industries
• Pre-treatment for seawater desalination