With the support of the Spanish Ministry of Economy and Competitiveness, LEITAT is participating into a project called MINETOX focusing on the accumulation of waste scattered in the landscape due to mining activities.
Mining activity results in the accumulation of waste scattered in the landscape. When trace elements contained in the wastes are mobilized, they can be transported in drainage waters increasing the risk of pollution of surrounding ecosystems. This pollution not only degrades the quality of soil, aquatic and atmospheric environment, but can also affect crop growth, causing serious problems to human health.
Remediation of soils contaminated with trace elements is mainly based either on the extraction or on the stabilization of the contaminants. Stabilization is based on the use of amendments to accelerate the processes of sorption, precipitation, and complexation that naturally take place in soils to reduce mobility and bioavailability of trace elements. Biochars are biological residues combusted under low oxygen conditions, resulting in a porous, low density carbon rich media. The use of biochar is inexpensive and sustainable because the substrates are waste products and their incorporation uses simple low energy mechanical mixing techniques.
In this project, we apply two types of biochars (from municipal solid wastes and from sewage sludge from a waste water treatment plant) as amendments capable of immobilizing trace elements whilst also providing a medium suitable for the re-vegetation of mining waste. The overarching aim of this project is to evaluate the toxicity of two different types of mining wastes using a battery of bioassays. The bioassays will be selected in order to take into account the pathways along which organisms will be exposed to pollutants in wastes. Firstly, we will assess the toxic effect on enchytraeids who will be exposed to the fraction of pollutants dissolved in the soil pore water. Secondly, the uptake of pollutants adsorbed to solid particles and the toxic effect of the mining wastes (bulk) will be tested in enchytraeids and earthworms.
The toxicity data obtained from these bioassays will be compared with the physicochemical properties characterized in each treatment to assess the effectiveness of the different biochars in remediating mining wastes.
Click here for the Spanish version of the description of MINETOX.