Ariseo Water Tech

Ultrafiltration is a tangential flow, pressure driven filtration process that separates particles on the basis of their molecular size. Pore diameters of ultrafiltration membranes are in the range of 10 to 200 A (0.001 to 0.02 micron). Solvents and species having a diameter smaller than the pore size of the membrane will pass through the membrane and emerge as ultrafiltrate known as permeate. Rejected species are progressively concentrated in the retained stream.

Ultrafiltration membranes are reusable and cleanable with standard chemicals.

Ultrafiltration of process water provides

• Removal of virtually all-particulate matter, suspended solids, bacteria, viruses and pyrogenic species from pharmaceutical and industrial process water.
• Removal of colloidal material (non-reactive silica, iron, aluminum etc).
• Removal of high molecular weight organic.

The ultrafiltration membrane is a thin polymeric material (Polyether sulphone) with an anisotropic pore structure. This means the membrane does not have the same pore structure throughout its matrix.

Instead of anisotropic membrane has a surface with small pore diameters and a support structure which has a pore size up to approximately 15 microns. The combination of the very smooth surface with small pores and the support structure with much larger pores results in filtration of small particles with a low resistance to flow.

The difference in pressure between the feed and reject streams will determine the flow of water across the surface of the membrane. The pressure difference between the feed stream and the product side of the membrane is directly related to the product flow. When the pressure is applied to the feed stream, it flows tangential to the membrane surface. Ultrafiltration is a dimensional separation process. Generally ultrafiltration membranes are rated on their Molecular weight Cut off, abbreviated MWCO. This is an indicator of the relative size of the globular molecules which a membrane will remove Indion Membrane systems has ultrafiltration membranes with MWCO ranges between 50000 to 200000. The aqueous phase and material smaller than the membrane’s nominal MWCO will pass through the membrane. Therefore, the product stream will contain water, ionic species and low molecular weight material, whereas the membrane will reject colloidal matter, particle bacteria, viruses, and pyrogenic species.

As with most conventional filtration methods, sand filters and media filtration require consistent raw water quality to deliver quality effluent, which is not always possible. They also don't provide an absolute barrier. Traditional media filters typically remove particles to down to about 5 microns.

Ultrafiltration (UF), however, does not suffer from those limitations. This technology uses an ultrafiltration membrane barrier to exclude particles 0.02 to 0.05 microns, including bacteria, viruses, and colloids, meeting increasingly stringent water-quality standards around the world, and providing a stable, reliable, and consistent water quality.

UF offers:

• High and consistent product quality measured by turbidity (NTU) or silt density index (SDI).
• Tolerance to feedwater quality upsets.
• No use of pretreatment chemicals (polymer, coagulant, pH adjustment) and associated costs for sludge disposal.
• Small footprint and less weight than media filters.

When used as a pretreatment for reverse osmosis (RO) , UF also helps reduce fouling of the RO membranes, which can lead to:

• Reduced chemical cleaning frequency and consequently, lower operating costs and downtime.
• The potential to operate RO at higher flux, with fewer membranes and vessels — leading to lower capital cost for the RO system.