Evaluation of the critical parameters on the removal efficiency of a botanical biofilter system

Abstract

Volatile organic compounds (VOCs) have increased public concern in terms of their adverse effects on health. Amongst VOCs, formaldehyde is significantly found indoors which can cause lung, leukemia, and nasopharyngeal cancers. Therefore, the requirement to find a suitable method and diminish the energy consumption of buildings has increased. Recent progress in vertical greenery systems has led to active systems known as active botanical biofilters. The current research represents an assessment of several essential parameters, based on the full-factorial model, for determining the functionality of a modular botanical biofilter and evaluating the role of plants and substrate to remove formaldehyde from the gas stream. Our findings showed that the maximum formaldehyde single-pass removal efficiency (SPRE) of 99.99% occurred at the lowest air flow rate (0.8 L/s) and concentration (0.3 mg/m3) through the 0.25 m2 filter, with any increases in air flow rate, met with a reduction in efficiency. At the same time, the utmost Clean Air Delivery Rate (CADR) of 17.46 m3/h was achieved at 5.5 L/s and 0.3 mg/m3. However, the system met the maximum Elimination Capacity (EC) of 30.64 mg/h at the highest inlet airflow (5.5 L/s) and pollutant concentration (2.06 mg/m3). Despite the role of biofilter segment to remove formaldehyde, the botanical components were found to be responsible for the system's SPRE of 13.51–28.07%, CADR of 0.39–5.46 m3/h, and EC of 0.12–11.45 mg/h. If the system is to meet current air standards, further development is required to increase its elimination capacity.