Mise au point de procédés pour le traitenement ex-situ par phyto-remédiation des sols contaminés en hydrocarbures pétroliers et/ou en métaux

The large scale ex-situ biological treatment of moderately contaminated soils (at the Level B-C according to MDDELCC standards) represents a high potential market in Quebec (including mixed contamination with hydrocarbons /trace elements,TE). Several hundred target areas have already been listed representing several million cubic meters of contaminated soils (1). The most widely used ex-situ industrial treatment in the last thirty years is the bioventilation (50% of treated soils in Quebec). No process currently uses plants as an active vector in the degradation of contaminants (principle of phytoremediation) in any ex-situ process. Some plants have indeed the ability to absorb TE and to degrade most hydrocarbons either directly or indirectly by stimulating soil microbial activity via the secretion of root exudates. We propose to develop a new bioprocess ex-situ treatment of moderately contaminated soils combining various approaches developed by the researchers of this project over the past decade. This bioprocess that integrates plants and microorganisms will be tested on a demo site based in Neuville. For the plant component, we will use a new propagation and implantation technique developed by our research team which allows to establish a fast growing « agressive » vegetation (willows) characterized by an large root system efficient to degrade and/or absorb the targeted contaminants. Diverse cultivars (as microcuttings) will be used for the treatment of the contaminated soils as well as to favor the development of an efficient microbial community for the bioremediation. For the microbial component, we will focus on microorganisms known to establish mutualist relationships with plants and to favor their growth (will be inoculated with the microcuttings mixed to a compost matrix) as well as on the microbiome, naturally present in contamined soils that play a key role in the degradation of organic pollutants, that will be stimulated by specific cultural interventions. We will test several combinations plant genotypes / microorganisms in a variety of soils and contaminants and the impact of different inputs known to stimulate the soil microbial activity. Experimental designs will be set up in order to guaranty statistical validation of the results. The composition, stability and the relative performance of each process components will be analyzed through meta-genomics /-transcriptomics (analysis of microbial and plant populations actually recruited in the degradation process of organic contaminants), biomass production and contaminants follow up of in soil and plant tissues.