Since the end of the ’80s, it has been known that potted ornamental plants can remediate Volatile Organic Compounds (VOCs) from indoor air and, to date, a significant number of species have been tested in controlled environments to quantify their abatement capacity concerning specific VOCs. However, the experimental methodologies are not standardised yet, and different units and approaches are used to quantify the removal capacity of the species. Consequently, in most cases, the results obtained are not comparable and, most importantly, directly exploitable to set up phytoremediation interventions in real settings.
This study proposes a new method for evaluating and comparing the VOC removal capacity of different plant species and a review, produced according to this methodology, of the results obtained in previous studies. Considering that the VOC abatement is related to the entire plant system and that the uptake cannot be considered neither a zero nor a first-order removal process but a hybrid of the two, the proposal consists in modelling the removal analogously to biological processes. In the first instance, this approach allows a simple but effective assessment of the results obtained in different tests, making possible an objective choice of the best performing species for phytoremediation applications in real settings. While applying this methodology to existing experimental studies, it was considered essential to rigorously review their protocols as the removal depends on many factors, inter alia the chamber dimensions, the environmental conditions, the initial pollutant concentrations and the metabolic characteristics of the tested species. This application has aimed to set the basis for an accurate and more complete comparison of the results obtained in controlled environment experimentations and, also, to prepare the way to a standardization of the methodologies.
Plant-based remediation interventions could be a simple, green and innovative solution to address the complex indoor air pollution problem. The approach proposed in this paper is an essential step towards a rational design of these interventions, allowing, in particular, the assessment of the actual remediation capacity of different plant species tested in various conditions.