Acclimatization and real-time performance of botanical biofilters eliminating indoor volatile organic compounds using SIFT-MS

Abstract

Irrespective of a country’s development, people are exposed to mixed indoor volatile organic compounds (VOCs), such as carcinogenic benzene and formaldehyde. A botanical biofilter (BB) is a technique that integrates plants, substrates, and their associated microbiomes to collectively eliminate VOCs. Nonetheless, the startup time, the impact of indoor conditions, and the foliage’s contribution are insufficiently examined. Hence, this work investigates the effect of acclimatization and boundary conditions on BB performance by real-time VOC quantification. Two BBs (Epipremnum pinnatum) were acclimatized to a five-fold concentrated (against maximum indoor guidelines) mixture of priority VOCs (BTEX: benzene, toluene, ethylbenzene, xylene; AF: formaldehyde, acetaldehyde) to induce removal. Then, VOC levels were reduced to indoor levels in the first BB (one-fold), and VOC removal was quantified. The resilience was assessed by interrupting the VOC supply (35 days) and reactivating it. In contrast, the second BB was maintained at five-fold concentration and subjected to varying airflow rates using mixed and single VOCs. Results showed that acclimatizing both BBs increased their BTEX removal five-fold, shifting from an exponential to a linear decay behavior. AF removal did not exhibit a shift and was faster than BTEX removal. Reducing VOC concentration in the first BB, enhanced BTEX removal, and the unit regained performance after shutdown. In contrast, the second BB demonstrated that while increasing the airflow rate enhances the VOC elimination capacity, the order of applied airflow impacts performance, besides ongoing acclimatization effects. Finally, it was estimated that the foliage actively removes VOCs, contributing to the overall system’s performance.

Keywords: Acclimatization, Bioremediation, BTEX, kinetic behavior, Phytoremediation