Giant reed (Arundo donax L.)—A multi-purpose crop bridging phytoremediation with sustainable bioeconomy

Arundo donax L. (giant reed, Poaceae) is a perennial, lignocellulosic non-food crop. It is characterized by high yields and high water and nitrogen efficiencies, and by low susceptibility to pests and diseases. Its biomass can be used for the production of bioenergy, second generation biofuels, paper pulp, wooden building materials, and a cascade of different biobased products in a biorefinery scheme such as nanocellulose. Its robustness and physiological characteristics, such as a deep, dense, and extensive root system, allow it to easily adapt to different types of soils and ecological conditions. Those features represent an opportunity to use this crop in the removal of pollutants from wastewaters (WW), as a strategy to improve the management of water resources, or in the phytoremediation of contaminated soils to restore or attenuate and stabilize contaminated sites while bringing additional revenue to owners. In this context, A. donax production under WW irrigation or in contaminated soils is reviewed, with the aim of identifying benefits and limitations. Bridging phytoremediation with the production of this multi-purpose crop could provide environmental benefits and social and economic opportunities, improving the overall sustainability of the biosystem. Reports of laboratory, pilot, and field researches indicate that this crop has the potential simultaneously to deliver high yields, restore soil properties, and improve water quality. Moreover, the use of this crop in contaminated land contributes to reduce the risks associated with land use change associated with the cultivation of non-food crops. Nevertheless, due to the presence of harmful substances in WW or soil, and its effects in the biomass yields and quality, up-scaling its application should be evaluated at each locally, technically, environmentally, socially, and economically.