Suitability of Salicaceae Genotypes in a Phytotechnological Approach to Industrial Wastewater Treatment and Biomass Production

Water circularity is a challenge which must be met to guarantee the sustainability of this resource. Woody biomass is another resource of interest for the bioeconomy, which has multiple uses and acts as a carbon sink. Combining both aspects involves establishing wastewater irrigated plantations, the so-called Vegetation Filters. The aim in this research was to contribute towards assessing the suitability of different Salicaceae genotypes for enhancing the efficiency of these simultaneous processes. Twenty-three genotypes of different species and hybrids of the genera Populus and Salix were irrigated using brewery wastewater under controlled conditions (in a greenhouse using hydroponic cultivation or in pots with substrate) and in the field. Although the application of wastewater reduced the overall production, relevant differences between the genotypes were detected. Growth, physiological activity and nitrogen attenuation efficiency provided good criteria for selection, although given the interaction with site conditions it is essential that plant material is selected based on its adaptation to the environment. The poplar hybrids ‘2000 Verde’ and ‘I-214’ showed the highest rates of net photosynthesis and transpiration, with high percentages of N removal and moderate biomass production, these two initially being considered of interest for the purposes outlined above. The ‘AF34’ genotype showed the highest production in the field, followed by the ‘Levante’ willow hybrid. The white poplar ‘PO-10-10-20’, which presented moderate production in the field, is also of interest due to its autochthony, which can be advantageous in certain environments. The latter two also showed high attenuation percentages for the evaluated pollutants.