Types of initiative
Acuamed administers 80% of the Ministry of Agriculture, Food and Environment's A.G.U.A. Programme. These entail over a hundred initiatives which are already being implemented throughout the Mediterranean Basin, from Girona to Málaga.
These initiatives will serve to provide 850 cubic hectometres of water per year for various uses. 50% of these new resources will be achieved thanks to desalination, 20% through the reuse of waste water, 15% as a result of irrigation modernisation and the remaining 25% through the exploitation of surface and ground water and other improvements.
Initiatives to increase the availability of water resources.
DESALINATION
Desalination is the process by which seawater can be turned into a fully usable water resource, both for human supply and for irrigation and industrial purposes. This involves separating out the salts contained in seawater to reduce the levels to approximately 0.5 grams per litre of drinking water.
What we refer to as water covers a range of natural solutions varying from 0.2 g of salt per litre in very pure mountain spring water to 35 g in seawater. Water for human consumption may not have more than 1 g per litre nor be distilled water. Nor should it be too poor in salt.
Desalination can be performed by various techniques, such as distillation, freezing, instantaneous evaporation or the formation of hydrates, although these days reverse osmosis is the most heavily employed and widespread method.
A reverse osmosis desalination plant operates in a very simple way. Located close by the sea, it takes in water by means of pipelines which discharge into channels where the water is cleaned of sand and impurities by means of filters and chemical elements.
The reverse osmosis desalination process then begins. Osmosis is a natural phenomenon which occurs in the cells of living beings whereby two solutions of different concentrations tend to balance out their concentrations across a membrane, from the more dilute solution to the more concentrated one, eventually achieving equilibrium.
Reverse osmosis involves applying pressure to the more concentrated solution in order to obtain a greater quantity of the dilute solution. In this case, a greater quantity of salt-free solution.
This requires a turbo-pump capable of applying considerable pressure to the membrane, and so separating the salts in the membrane housings, breaking the hydrogen bonds and reducing the salt crystals.
Once the water has passed through the membranes it will have been separated into two types:
- Salt water which is channelled back to the turbo-pump to recover some of the energy invested in the desalination process, and is then returned to the sea, generally at sites with considerable water movement, such as a breakwater, to ensure that it mixes properly with the seawater so that the residual salt does not cause any ecological damage.
- Drinking water is piped to storage tanks, where minerals are added to make it more effective for crop irrigation and to improve its quality for human consumption in accordance with all Health Department standards.
The application of desalination has served to resolve many serious water shortage problems. At present more than 63 million cubic metres of desalinated water are produced each day worldwide, enough to supply a population of more than 150 million inhabitants.
Desalination coverage extends throughout the world, and is particularly important in countries such as Saudi Arabia, the United Arab Emirates, the United States, Australia and Europe, with a particular focus on Spain, where it has been in use since the 1970s, first in the Canary Islands, later in the Balearics, on the mainland and in the enclaves of Ceuta and more recently Melilla, with output of approximately 1,200,000 m3/day, 700,000 m3/day of which is desalinated from seawater, and the remainder from brackish groundwater.
Initiatives to improve water resource management.
WATER TREATMENT
Water treatment involves freeing the water of any form of impurity which it may contain, allowing it to be reused from industrial and agricultural purposes. Such practices are widespread throughout Spain.
The treatment process begins with the waste water arriving at the treatment plant, where it is first filtered in order to remove all the waste substances which the water contains, allowing the subsequent treatment processes to be properly performed.
A series of pools (decanters and reactors) are then used to separate out the detritus using physical and biological means. The resulting sludge is absorbed and taken to treatment plants where it is converted into fertiliser.
By the end of the process, the water is ready for reuse in agriculture and industry.
Environmental and ecosystem regeneration initiatives.
The restoration of the hydrological environment and the preservation of water resources demand a series of interrelated actions dealing with improvements to wetlands, the conditioning of riverbanks and habitats and improvements to water quality. River watercourse conditioning programmes are also being conducted.
The A.G.U.A. Programme desalination initiatives likewise cover the application of various solutions to any possible impacts on meadows of Posidonia oceanica, one of the most important Mediterranean sea grasses, listed as a habitat of priority Community interest.
The CEDEX (Centre for Experimentation and Public Works Studies) and the Directorate-General for Water at the Ministry of Agriculture, Food and Environment have effective methods in place intended to apply measures to minimise possible impacts.
