Volatile organic compounds (VOC) are ubiquitous in the indoor environment and can affect human health negatively. Potted plants are a potential green technology solution for removal of VOCs. This PhD project aimed at reviewing current literature on VOC removal by potted plants, developing a dynamic chamber system for improved real-life simulations, investigating the effects of VOC concentration, light intensity, CO2 concentration and temperature on VOC removal, applying advanced data analysis techniques for investigating removal of a complex mixture, and exploring the effect of a complex mixture on microorganisms in the soil of potted plants.
The review of literature on indoor VOC removal by potted plants identified pathways for VOC removal to potentially be by aboveground and belowground plant parts as well microorganisms in the soil and the soil itself. The rate or efficiency of VOC removal by potted plants is dependent on plant species and can be affected by factors such as light intensity, temperature and VOC concentration. The literature review identified future research needs which led to the development of the dynamic chamber system. This system allows for an improved real-life simulation by allowing air exchange and continuous emission of a VOC or VOC mixture. The system was operational in dynamic and semi-dynamic mode which highlighted that experimental set-up can affect calculated removal rates.
With exposure to toluene Hibiscus rosa-sinensis was not affected by an increase in light intensity and CO2 concentration or temperature whereas Hedera helix showed both positive and no effect of increased light intensity and CO2 concentration. An increase in temperature resulted in increased removal of toluene for H. helix. The percentage of toluene removed was unaffected by VOC concentration whereas the amount removed increased with increasing VOC concentration. Exposing H. helix to a complex mixture of VOCs and applying advanced data analysis techniques revealed that plants are able to remove a vast amount of compounds at the same time. This is of significant value for the application of potted plants for VOC removal in indoor environments where hundreds of compounds co-exist. The impact of a complex mixture on the microorganisms in the soil was an increase in toluene mineralization, decrease in bacterial abundance and change in the bacterial community structure. The change in bacterial community structure was, however, not the same for two consecutive experiments indicating that several bacteria can degrade VOCs