Samples confirm success of the passive treatment technique of water deriving from mining activity

The results of the first year of the water treatment pilot plant located in Mina Concepción are highly favourable to the LIFE ETAD project

The assessment of the first working year of the passive treatment plant of Mina Concepción (Huelva), created within the framework of the Life ETAD project could not have been more positive. Thirteen complete samples were analysed, and the behaviour of the acid drainage under treatment and purification process afterwards interpreted. After the intervention in a total amount of 20.225 cubic meters of acid drainage, it has been possible to fully eliminate compounds of iron, arsenic, chromium, aluminium, copper, lead, zinc, cadmium and magnesium, besides 95% of copper and nickel and till 68% of the sulphate. Besides, the drain water stemming from the drainage process resulted in a ph level higher than 7, the electric conductivity has been reduced to less than half, and, in short, the treatment plant managed to convert contaminated acid waters in fully alkaline water.

The acid mine drainage consists of water that undergoes an alteration of its PH to acid levels in areas where mining activity took place. Bearing in mind that the Odiel basin contains some of the most contaminated water in the world, this is the framework for an experimental technology developed by the University of Huelva, which is undergoing a validation process. This experimental technology consists in purifying the water by means of a reactive reservoir and decanting tanks arranged in line to where the water is conduced.

The Life ETAD project is sponsored in 50% by community funds, was the promoter of the construction of the acid mine drainage plant in Mina Concepcíon, in a partnership with the University of Huelva, the Sacyr company and the Agencia de Medio Ambiente y Agua de Andalucía. The plant started working in April 2017, with an immediate intervention in the main local drainage. Notwithstanding the forced summer gap due to the lack of water flow, the success of the results overcame the initial expectations and the impact of the interruption returned null.

The Mina Concepción plant counts on several reservoirs containing a reactive material that will allow the improvement of the water quality, after it has undergone the complete process. The design of the equipment has been thought to work by means of gravity, thus avoiding the consumption of electricity. With this plant is intention of the Life ETAD project to present a low-cost solution for the acid mine drainage water. Likewise, the project will be followed-up by reusing the waste derived from the purifying process, - the result of the mix of radioactive material with the decanted metals -, as these have a great interest for industrial and technological usage.

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