Developing eco-innovative chemical processes to valorise phytoremediation-borne biomasses : the PHYTOCHEM initiative

Industrial and urban activities impact our environment, especially in terms of soil pollution. During the last two decades, gentle soil remediation techniques have emerged using various plant species and the combination of microbial biotechnologies. Several phytotechnologies can be applied to produce useable biomass, alleviate pollutant linkages and restore services of polluted soils: (1) phytostabilisation, which uses perennials able to sorb and immobilize trace elements (TE) in excess in the root zone, avoiding their transfer toward groundwater and aerial parts and preventing their bioaccumulation in the food chain as well as dispersion by natural agents (2) phytoextraction, based on root-to-shoot transfer and storage of TE in harvestable plant parts. The PHYTOCHEM project aims at promoting chemically-based valorisation processes of the plant biomasses collected from polluted sites managed by eco-innovative phytotechnologies. As a first step towards the development of chemically-based valorisation processes of plant biomasses collected from polluted sites, we have successfully implemented 16 and 18 woody species at two phytomanagement sites in 2014 (Figure 1). Based on ICP-AES analysis, TE concentrations in aboveground tissues highly varied, illustrating the metal tolerance processes developed by plants, either by exclusion or accumulation. We further applied chemical processes to contaminated biomasses. For instance, optimization of an organosolv pre-treatment allowed for removing ca. 50% of Fe and Mn from contaminated biomasses, while Ecocatalysis was also successfully applied to i.e. Zn hyperaccumulating species (A. halleri)