Active botanical biofiltration of air pollutants using Australian native plants

Abstract

Air pollutants are of public concern due to their adverse health effects. Biological air filters have shown great promise for the bioremediation of air pollutants. Different plant species have previously been shown to significantly influence pollutant removal capacities, although the number of species tested to date is small. The aim of this paper was to determine the pollutant removal capacity of different Australian native species for their effect on active biowall particulate matter, volatile organic compounds and carbon dioxide removal, and to compare removal rates with previously tested ornamental species. The single pass removal efficiency for PM and VOCs of native planted biofilters was determined with a flow through chamber. CO2 removal was tested by a static chamber pull down study. The results indicated that the native species were not effective for CO2 removal likely due to their high light level requirements in conjunction to substrate respiration. Additionally, the native species had lower PM removal efficiencies compared to ornamental species, with this potentially being due to the ornamental species possessing advantageous leaf traits for increased PM accumulation. Lastly, the native species were found to have similar benzene removal efficiencies to ornamental species. As such, whilst the native species showed a capacity to phytoremediate air pollutants, ornamental species have a comparatively greater capacity to do so and are more appropriate for air filtration purposes in indoor circumstances. However, as Australian native plants have structural and metabolic adaptations that enhance their ability to tolerate harsh environments, they may find use in botanical biofilters in situations where common ornamental plants may be suitable, especially in the outdoor environment.

Planning, Designing, and Managing Green Roofs and Green Walls for Public Health – An Ecosystem Services Approach

“…Unfortunately, smaller particles are more damaging to human health than larger particles (WHO, 2016), reducing the benefits from plants in this regard. However, removal of pollutants from the air may be damaging to the plant, and some studies argued that the plants which are most efficient in removal would not survive long in polluted environments due to accumulation of contaminants in plant tissues (e.g., Paull et al, 2019). However, a later study by the same authors found that many species of plants exposed to urban air can withstand the polluted environment and show no signs of reduced vitality compared with non-exposed plants (Paull et al, 2021).…”

“…Species traits has been shown to influence ability for air quality purification (Liu et al, 2021;Ysebaert et al, 2021). For instance, leaf morphology is an important factor in PM removal (Speak et al, 2012;Paull et al, 2019) and species with high photosynthetic capacity, stomatal conductance, and transpiration are efficient in removing all gaseous pollutants from the air (Baraldi et al, 2019). A review by Liu et al (2021) concluded that air quality purification ability is higher for intensive green roofs than for more extensive green roofs.…”

“…Several studies (Paull et al, 2018(Paull et al, , 2021 reported that the most common green wall plant species are able to withstand highly polluted environments. There were no conclusive results on species differences on the best capacity for survival and pollutant removal (Paull et al, 2021), although native Australian species seem to have lower capacity (Paull et al, 2019). In one study, edible plant species (Sedum lineare, Sedum sarmentosum, and Portulaca oleracea) grown on green roofs were found to accumulate heavy metals, especially cadmium (Cd), at levels rendering the plants inedible (Ye et al, 2013).…”

Active Botanical Biofiltration in Built Environment to Maintain Indoor Air Quality

“…In ambient conditions, this system demonstrated exponential decay for all the targeted air pollutants; however, the study indicates a requirement for in situ long-term assessment. The use of native Australian plants and their efficiencies in an ALW system was assessed; the performance of native and ornamental plants was compared (Paull et al, 2019). Single-pass removal efficiency revealed the less effective nature of the native Australian plants for the removal of PM and CO 2 when compared with the common ornamental plants.…”

A Scientometric Analysis of Research on Bio Filtration of Waste Gas Streams During 1989-2020

“…In a biofilter, the biomass mains to elimination of pollutants over time, which has been connected to growth in flow rate of air in the bed. Biomass gathering is better at the commencement segments of the biofilters, and leads to a variation in bed features e.g., decrease in inter particle void space, and the compaction of natural packing material like wood chips; these variations source for channeling and better pressure drop (Ryu et al 2010;Xi et al 2015;Paull et al 2019). In overall, there is an around linear growth in pressure drop with growing gas flow rate, which starts to develop exponential at higher flow rates.…”