Technology

The reverse osmosis desalinators are universally used in the marine and shipbuilding industry to obain fresh water from the seawater, and they are widely used for civil and residential use, for industrial and agricultural field, to purify sea water, brackish water or otherwise raw waters not directly usable for their characteristics.

Regardless of the size and capacity of the system, a RO desalinators (Reverse Osmosis) performs its function through three basic stages:

• pre-filtering and / or chemical pretreatment of the raw water
• pressurization
• the flow through the reverse osmosis section and the separation of the salts

The incoming pre-filtering eliminates all suspended particles in the seawater and reduces its turbidity, by a passage through the filters which hold them physically. Generally plastic filters are used, you can use quartzite filters when you have to process a very turbid water.
This preventive process, providing a first improvement of water quality, also has the important function to prevent that the suspended particles, flowing directly to the reverse osmosis unit, can compromise quickly its efficiency and effectiveness.
When necessary or desirable, it may be added to a section of chemical pre-treatment.

The HP pump (High Pressure) imparts to the water the proper pressure required to entry in the reverse osmosis unit. This pump (or group of pumps in medium-large size systems) has features and benefits depending on the type of water to treat (sea water or brackish water) and the required production capacity.

The reverse osmosis unit separates the salts still present in the water, generating a certain percentage of fresh water – the permeate – and discharging the remaining concentrate. The ratio between permeate and concentrate provides a measure of the efficiency of the entire process, which increases with the increase of the size of the plant. The RO unit can be composed of one or a few membranes in a single vessel (the container that houses them) in small household desalinators or for boating, up to thousands of vessel in onshore plants which guarantee drinking water to entire communities.

The fresh water obtained can be further treated, if necessary, with a UV sterilization, that definitively breaks down the bacterial and pathogenic load; with a post-filtration active carbon, to improve the organoleptic characteristics; with a chemical post-treatment (chlorination, for example), for greater safety of preservation in the storage tanks.

The entire process is managed by an electronic control and by an instrumentation of manual or automatic command and control, depending on the complexity of the machine or plant.

Any desalinator needs a complementary flushing system (manual or automatic), useful to conduct periodic washes with fresh water, and to ensure efficiency and durability of the machine and its components.

The choice of a desalinator in standard configuration or the design and production of a specific installation are always subordinated to the capacity of which you need, the characteristics of raw water to treat and the quality of fresh water you want to obtain.