membranes
Technologies - Membranes
A membrane is any material that, in the form of thin films (0.05 mm to 2 mm), have the property of selectively opposing the transfer of different components found in a liquid or gas fluid and, therefore, allowing certain elements making up this fluid to be separated out (particles, solutes or solvents).
Since the first cellulose acetate reverse osmosis membranes appeared on the market, a large number of organic (polymer) or even mineral (obtained, for example, by sintering ceramic granules such as Aℓ203, silicon carbide, zirconia) membranes have gradually been added to the list.
Composite Membranes
These techniques have appeared more recently and allow an extremely thin film to be formed on an existing porous support which is itself frequently asymmetric. As the two materials used together are different, this allows us to make the best use of the properties of both materials: mechanical in the case of the one and selective in the case of the other. Thus, TFC (Thin Film Composite) osmosis membranes have a polyamide semi permeable layer well below 1 µm laid over a substrate which will often be a polysulphone ultrafiltration membrane.
Desalination And Clarification Membranes
With these membranes, water is the phase that is preferentially transferred via filtration under the effect of a pressure gradient. These membranes have often been called filtration membranes or permselective membranes (selective permeation membranes) and classified according to pore size or to the size of solute and particle they screen out. In effect :
reverse osmosis membranes are dense skin, asymmetric or composite membranes that let water through while, ideally, rejecting all salts.
nanofiltration membranes are reverse osmosis membranes that only really reject multivalent ions and organic solutes that are larger than one nanometre or approximately 300 g · mole–1 whence their name;
ultrafiltration membranes are asymmetric or composite membranes having a 1 to 50 nm pore size: they allow mineral salts and organic molecules through and only reject macromolecules;
microfiltration membranes are porous membranes that are most frequently homogenous or slightly asymmetric. Pore sizes are between 100 nm (0.1 μm) and 10 μm. They allow almost every dissolved species through and only retain solid particles.
conventional filtration transfer mechanisms (convective transfer of water in a porous medium and filtration/screening of particles that are larger than the pores) that are quite appropriate to microfiltration and to “loose” ultrafiltration become inappropriate to nanofiltration and reverse osmosis membranes where the mechanism is based on diffusion.
We could distinguish from those membrane the membrane that partly or totally rejecting salts, called desalination membranes and clarification membranes the one which totally eliminates suspended solids that cause turbidity without altering the water’s saline composition.
Reverse Osmosis Water Treatment
Simple, safe and cost-effective water purification using a semi-permeable membrane
What Is Reverse Osmosis?
Reverse osmosis (RO) is a water treatment process that removes impurities using a semi-permeable membrane. Simple, safe and cost-effective, it eradicates over 99% of contaminants from water such as dissolved solids, organics, bacteria and pyrogens.
How Does Reverse Osmosis Work?
Osmosis is the natural process by which a solvent (like water) moves across a semi-permeable membrane from an area of high to low concentration. RO water treatment reverses this process so the solvent flows in the opposite direction, resulting in highly purified water.
In RO systems, a pump creates pressure which forces the feed water through the semi-permeable membrane against its natural flow. The water molecules pass into a purified water tank, while contaminants are held back and discharged through a reject stream. The reject stream can be either safely disposed of or recycled in other processes.
What Are RO Water Treatment Systems Used For?
RO water systems can be used in a variety of industries such as pharmaceutical, healthcare, food & beverage and seawater desalinisation. Applications include decontamination, renal dialysis, wastewater recovery and process water production. RO works well in conjunction with other purification processes such as continuous electro-deionisation (CEDI) or ultrafiltration.
What Are The Benefits Of RO Water Treatment Systems?
RO water treatment is an established technology that offers many advantages over other purification processes. These include:
Lower operating costs and better energy efficiency due to ambient temperatures
Improved safety as no hazardous chemicals to transport, store and handle
Compact footprint which takes up less valuable space
No regeneration downtime as system continuously in operation
Treatment of any type of feed water
Integration with other water treatment systems
Simple to operate and maintain (e.g. integrated PLC control system, self-cleaning)
Ultrafiltration Water Treatment
Technology for removing suspended solids, bacteria and viruses from water
Ultrafiltration Water Treatment: An Overview
Our compact skid-mounted ultrafiltration system removes suspended solids, most bacteria and log4 viruses. The technology uses membrane filters and is most commonly used for industrial process water, borehole water and recycling/reuse water.
Water flow is directed straight through the membrane, or in a ‘cross flow’, allowing the membrane surface to filter out most colloids, enzymes, microorganisms, particles and endotoxins above their regulated sizes.
Ultrafiltration technology uses membrane filters with pore sizes of typically 1 to 10 nm, ensuring that it can remove particles as small as protein macromolecules.
Ultrafiltration Technology Benefits
This technology is excellent for ensuring consistent and pure water quality.
In addition:
No chemicals are used in the process other than for cleaning the membrane
Sustainable: efficient system operation limits energy usage
A regular high-speed flush can extend the lifespan of the system