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Decantation circuit of residual salts and ecological recovery of the Natural Park of Las Lagunas de la Mata and Torrevieja (CIRCUREVIEJA)
Start date: Jan 1, 2010, End date: Jul 30, 2011 PROJECT  FINISHED 

Background Salt production in the salt lakes of Torrevieja and La Mata has for more than two centuries maintained a stable level of water in both lakes. This situation has led over time to the creation of a wetland of great international importance for birds that is currently included on the Ramsar list. This area is also protected as part of the Natura 2000 network and as a natural park. While industrial saline activities have had some positive environmental impacts, progressive silting of the Torrevieja salt lake is a cause of concern. Accumulation of mud is linked to rain water runoff and gypsum contained in the sea water as well as the brine coming from Pinoso. The salt extraction process in the Torrevieja lagoon also produces waste materials, and the salt obtained has to be cleaned using the brine of the lagoon before it becomes commercially viable. When the project started, the brine crossed a decantation circuit before returning to the lagoon, but this circuit was not efficient and 85% of the mud and gypsum are returned to the lagoon. The brine underwent a pre-wash using the brine from the lake in a cross current in the area marked “Isla” (island) and another wash in the installation called “el Lavadero” (the washing machine). It is in these two places that these residues accumulated. Objectives The project aimed to: Reduce residual salts discharged in the lake of Torrevieja, a priority habitat according to the Habitats Directive; Aid the ecological recovery of the old decantation area – i.e the proliferation of endemic spices and extension of the Audouin’s seagull nesting area; Improve the environmental management in residual stockpiles of salt; and Spread environmental awareness. Results LIFE funding enabled NCAST to construct an improved brine decantation circuit to solve the environmental problem associated with inefficient decantation. This new circuit has led to a 66% reduction in residual volume discharged into the lake. It also accumulates all residues in one single spot, thus avoiding the destruction of possible vegetation growth areas. The reinforcement of the last dyke of the circuit allows the maintenance of the residual salt stockpile area in dry conditions. This land surrounding, surrounding Torrevieja lake, has been extended to 35 ha. It is likely to become vegetated again and therefore can be used for the Audouin’s gull and other nesting birds as their nests will not be flooded by the brine. Moreover, this area can be colonised by the habitats 1510* (Mediterranean salt steppes), 1310 (Salicornia and other annuals colonising mud and sand) and 5330 (Thermo-Mediterranean and pre-desert scrub). The construction of the decantation circuit has led to an increase in the number of potential nesting sites over an area of 35 ha that was previously constantly flooded. Now this land is dry and favourable for nesting. As a result, the population of Adounin’s seagull has steadily increased and the lakes have become the second most important nesting site in the Mediterranean. The construction of the brine decantation circuit is transferable to other salt marshes with a salt extraction system (by means of a permanent flooded lagoon) similar to the Torrevieja one. One objective of the project, however, wasn’t fully realised: the proliferation of planted species, with the view to providing food for the Adouin’s seagull. But only 5% of the species planted survived owing to the extreme conditions of the lakes as well as the hitherto unknown presence of rabbits. Nevertheless, the area is being naturally re-vegetated by vegetation already existing alongside the area. The beneficiary has also improved the methodology for future plantations which has been incorporated in the After-LIFE Conservation Plan. Further information on the project can be found in the project's layman report and After-LIFE Conservation Plan (see "Read more" section).
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