Ecology at the service of mining decontamination of rivers

The contamination of rivers, consequence of the mining activity that took place for years in the past in the surrounding areas, might have run its course, thanks to a new ecologic water treatment, that will be implemented for the first time in the basin of the Odiel river in Huelva.

The work has been evolving thanks to the LIFE ETAD project, co-financed by the European Union, with the participation of the company Sacyr Construcción, in the quality of engagement partner, the Consejería de Medio Ambiente, through Agencia de Medio Ambiente y Agua and the University of Huelva. Speaking to Efe, José Miguel Nieto, the researcher of the University of Huelva in charge of the project, explained that the mine acid waters are “the result of the interaction of water with sulphides and mine waste, filled with acid and metals” and that end up in the river basins contaminating the water, as in the case of the rivers Tinto and Odiel in Huelva.

 For this reason, the developed system, that presented positive results both in laboratory and in small scale on the field, applies a treatment that “allows turning these contaminated waters into clean waters, in an ecological, low cost manner”.

Ecological, because it does not consume electricity nor reagents”, it is a “passive treatment”, the “energy cost” is “zero, since the design of the equipments has been thought to work by means of gravity, the water to flow from a part of the system to the other and the cost of consumables to be minimum, since only small grains of limestone and calcium carbonate are used as reactive substrate”.

Presently, researchers are committed to collecting data that will allow sizing the equipments to be installed by Sacyr in 2015 in the upper part of the Odiel basin, and are confident about beginning to  monitor the results by the end of the year.

In the referred plant, the water PH levels close to 3 - the level to be found in contaminated rivers - will be risen above 6, a level in which the dissolved metals precipitate, with resource to reactive filters to which a technological innovation has been applied to prevent these filters from collapsing.   

Nieto highlighted that the novelty of this system is its technological innovation: “This passive treatment system had already been tested for metal contaminated waters derived from the coal extraction in mines in the USA, Canada and England, but as the filters blocked and lost their permeability which stopped water from flowing, it was only possible to make this process last for a week”.

“The technical innovation, in our case, consists of applying a system that allows, at the same time that metals are precipitated, as the filters lose their primary porosity, they generate a secondary one by means of dissolution”, he explained.

With a patent in register proceedings, Nieto ensures that this treatment system opens the possibility to decontaminate many rivers with a similar problem to those of the Iberian Pyrite Belt and stresses the fact that the system has already drawn the attention of South American countries, of South Africa and of Japan. The previewed results state, for that reason, the viability of passive technologies for acid mine drainage, the improvement of the quality of the water in the area and the use of new technologies that would solve a serious environmental problem of waters affected by the mining activity.


Source: EFEverde

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