A technique that combines nanoparticles and bioremediation to decontaminate polluted soils

22 June, 2016
Suelos contaminados

NEIKER-Tecnalia, the Basque Institute of Agricultural Research and Development, is currently exploring a strategy to remedy soils contaminated by organic compounds that contain chlorine (organochlorine compounds). The innovative process consists of combining the application of zero-iron nanoparticles with bioremediation techniques. Taking part in this project, known as NANOBIOR, are the companies Ekotek and Dinam, the University of the Basque Country and Gaiker-IK4.

 

Soils affected by organochlorine compounds are very difficult to decontaminate. Included among these organochlorine compounds are some insecticides mainly used to control insect pests, such as DDT, aldrin, dieldrin, endosulfan, hexachlorocyclohexane, toxaphene, chlordecone, mirex, etc. It is widely known that the use of many of these insecticides is currently banned because of their environmental impact and the risk they pose to human health.

 

To degrade organochlorine compounds (organic compounds whose molecules contain chlorine atoms) present in the soil, the organisations participating in the project are proposing a strategy based initially on the application of zero-iron nanoparticles that help to eliminate the chlorine atoms in these compounds. Once these atoms have been eliminated, bioremediation is carried out (a process in which microorganisms, fungi, plants or enzymes derived from them are used to restore an environment altered by contaminants to its natural state).

 

The bioremediation process being developed by NEIKER-Tecnalia consists of two main strategies: biostimulation and bioaugmentation. The former consists of stimulating the bacteria already present in the soil by adding nutrients, humidity, oxygen, etc. Bioaugmentation is based on applying bacteria with the desired degrading capability to the soil. As part of this process, NEIKER-Tecnalia collects samples of soils contaminated by organochlorine compounds and, in the laboratory, isolates the species of bacteria that show a greater capability to degrade these contaminants. Once the most interesting strains have been isolated, the quantities of these bacteria are then augmented in the laboratory and the soil needing to be decontaminated is then inoculated with them.

 

Bank of effective strains to combat organochlorines

Identification of bacterial species capable of degrading organochlorine compounds, so as to have a bank of interesting species for use in bioremediation available, is the first step for NEIKER-Tecnalia. This bank will gather strains collected in the Basque Country and will enable bacteria for use as a soil decontamination element to be made available.

 

Combining the application of zero-iron nanoparticles and bioremediation means a significant step forward in the field of soil decontamination and offers the added advantage of its possible application in-situ. This methodology, which is currently in the exploratory phase, could replace other processes such as the excavation of contaminated soils so they can then be contained and/or treated. Moreover, this combination of both techniques makes it possible to reduce decontamination times, which would be much lengthier if only bioremediation were used.

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