The term “osmosis” refers to the extension of a liquid that passes through a semipermeable membrane from the compartment with greater water potential (lower concentration of solute) towards the compartment with lower water potential. In the reverse osmosis process, by contrast, pressure is applied to the “container” where the water is less pure, in order to overcome its natural tendency and thus reversing the natural osmotic flow.
The advantage of reverse osmosis over other methods of water treatment is that, in addition to removing the dissolved salts, it also retains bacteria, germs, particles and dissolved organic substances.
Reverse osmosis succeeds in eliminating the polluting particles of size up to one ten thousandth of a micron, as well as pesticides, pyrogens, viruses and bacteria, thus ensuring the absolute bacteriological purity of the water. It has been estimated that reverse osmosis can retain 90 to 99.9% of the substances dissolved in water. Therefore, it has become the most widely used filtration technology at industrial level, from the biomedical to the food industry, to the treatment of industrial wastewater and to the generation of drinking water from the sea.
HOW IT WORKS?
Reverse osmosis is a process of separating foreign bodies from water by using semipermeable membranes. The membranes allow the passage of water, but retain the dissolved mineral elements, colloids and bacteria. An osmotic membrane consists of a central core around which a semipermeable synthetic fabric is wound in a spiral. Membranes are generally classified according to standard dimensions expressed in inches (e.g. a 4040 membrane corresponds to a 40-inch long and 4.0-wide module), but also depending on the production capacity, indicated in GPD (gallons per day).
The water to be treated is pushed into the membrane by a pump, which exerts a higher pressure than the osmotic one, so as to obtain two outgoing flows: the that passes through the membrane constitutes the usable permeate (poor in salts), while the remaining part comes out with a high salt concentration, due to the accumulation of all the salts that have not crossed the membrane and it is the concentrate (rich in salts) that should be discarded.
CHEMICALS FOR REVERSE OSMOSIS PLANTS
To improve the service and ensure the functionality over time of reverse osmosis systems, there are several chemicals described below:
- ANTIPRECIPITANTS and DISPERSANTS: suitable for inhibiting the fouling of reverse osmosis membranes thanks to the dispersing and sequestering action of their active principles against encrusting substances. Specifically designed to protect against fouling from calcium and magnesium, they also prevent the precipitation of moderate amounts of silica, ferrous ions and sulphates. They are also compatible to produce osmotic water used in food industries and / or for drinking.
- DETERGENTS: used periodically on reverse osmosis systems for the regular cleaning of membranes. Their surfactant properties favor the elimination of ferrous and microbiological deposits already present in the circuit.
- BIOCIDES: very effective for quickly eliminating algae, bacteria and fungi. They are perfectly soluble in water and perform their bactericidal action regardless of the pH of the solution in which they are added.
BENEFIT OF REVERSE OSMOSIS
- Substantial cost savings;
- Improvement of energy efficiency;
- Constance of the quality of permeated water;
- Enhancement of the overall system performance;
- Availability of uninterrupted water 24 hours a day;
- Maintenance reduced to a minimum.
Find out more about water technologies in the industrial sector. Technoacque experts will be happy to provide you with any kind of information on water treatment plants, do not hesitate to contact us.
