Nutrition Spain , Salamanca, Thursday, April 30 of 2015, 11:53

In search of the best biotechnology for treating water contaminated with metals

The Centre for Water Research and Technical Development (CIDTA) of the University of Salamanca is the scientific coordinator of a European project that aims to treat industrial water that has been contaminated with metals with biotechnical procedures

José Pichel Andrés/DICYT The Centre for Water Research and Technical Development (Centro de Investigación y Desarrollo Tecnológico del Agua, CIDTA) of the University of Salamanca is coordinating for four years (2014-2017) a European project that seeks new biotechnologies for treating industrial water contaminated with metals. Spanish, Portuguese, and French researchers are currently studying at a laboratory scale three different processes for eliminating metals from water by means of various biological components and processes. Shortly and as from the third year of the project three demonstration plants will be built in three industrial factories, one from the mining sector, one from the metallic sector, and one from the ceramics sector.


“Industries generating effluents with a metallic content are obliged by regulations to have water treatment systems at their own factories, as the metallic pollutants of their sewage are particularly toxic and cannot be spilled into the environment or the drains. If they were to reach the corresponding municipal water treatment plant they would inhibit the processes of the treatment of urban pollutants”, Manuel García Roig, the director of the CIDTA, explains to DiCYT.


Despite the fact that industries are now taking these restrictions into account and treating their sewage, as it is desirable to reduce still further the content of toxic elements such as mercury, lead, and cadmium this European project known as the ‘BIOMETAL DEMOnstration plant for the biological rehabilitation of metal bearing-wastewaters’ is testing biological methods in order to achieve it.


On the one hand, the Universidad Complutense de Madrid and the School of Mines of Alès in France are working on a process of the bioadsorption of metals, making good use of the capacity of some biomasses of adsorbing these pollutants on their surface area to clean the waters containing them. The researchers are working with substances obtained from beetroot flesh, seaweed, and chitosan, an element produced from chitin which is present in the exoskeleton of arthropods and crustaceans.


On the other hand, the Universidad del Algarve in Portugal is working with bacteria that grow in the presence of organic nutrients in acid waters containing metallic sulphates. These microorganisms reduce the metallic sulphates, which are soluble in water, to metallic sulphides which are insoluble in water. In this way the sewage is left free of metals in the presence of the bacteria.


Finally, the CIDTA is working on "a system of the bioprecipitation of metals based on bacteria capable of biocatalysing the hydrolysis of organophosphates” as its director explains. This process, which is being studied at the University of Salamanca, is more sophisticated than the previous ones and the scientists have had some problems with the use of the phytase enzyme immobilised on keratin of pig hair remains. The research has therefore taken a new direction. “We have concentrated on a bacteria type isolated from industrial sewage contaminated with metals and with the capacity to biocatalyse the hydrolysis of organophosphates”, García Roig comments. The scientists want to check the efficiency of these microorganisms in achieving the precipitation of metallic phosphates and thus eliminating the metals from the water.


Choosing the best process


When the first two years of work are completed in December 2015, the results obtained from each method will be compared. The scientific committee for the project will choose the most efficient process or combination of processes for the construction of three pilot plants that will treat actual water practically full-scale.


Two of them will be installed in Spain at the Goñabe factory for metallised products in Valladolid and at the Endeka Ceramics company in Castellón; and another in Portugal at the São Domingos mine. Each of these cases has its own particular features, and the last two years of the project up to December 2017 will be used to follow up the biological treatment of their water under actual operating conditions.


As the idea for the project was born in Salamanca, from the outset the project has been scientifically coordinated by the CIDTA, together with the formalisation of the consortium of companies and researchers taking part in the initiative. The total budget is 4.3 million euros, of which 2.9 come from the European Union and the remainder is provided by the members.