Strategies for enhancing soil phytoremediation and biomass valorisation

Areas of contaminated land are expanding rapidly all over the world, contamination with heavy metals being of particular concern. Phytoremediation, a biologically based technology, is attracting the attention of both the public and scientists and is an attractive low-cost alternative for soil requalification. However, the fate of harvested biomass resulting from such phytoremediation may represent an obstacle for its implementation and strategies for the disposal and, desirably, valorization of this contaminated biomass are a necessity. In this chapter, this topic is discussed with particular emphasis on the use of this biomass as a by-product with added value, namely for the production of biomass-derived energy, within a circular economy concept. The use of biomass grown in degraded and abandoned soils may allow a decrease in the use of food crops for energy production, which has been criticized for leading to soil mismanagement, food shortages and price rises. Not involving agricultural soils for energy crop cultivation increases the sustainability of the utilization of biomass for energy generation, and it may allow an increase in the available agricultural soil through the consequent gradual decontamination of such brownfield sites. However, although it has been proposed theoretically as an excellent option, the information available concerning practical applications is very scarce, despite the considerable degree of success reported in the literature, as discussed in this chapter.