Evaluating botanical indoor air biofiltration for air quality enhancement: Investigating coconut and kenaf fibres as growth media

Abstract

Practical and eco-friendly solutions are needed to address indoor air quality issues. Active botanical biofiltration systems represent a promising approach to indoor air purification by combining plant-mediated pollutant removal with mechanical ventilation. This study assesses an active botanical indoor air biofilter (BIAB) prototype featuring a two-stage filtration system: contaminated air flows horizontally over plants and growth media, then through evaporative media to produce purified air. The research examined five growth media configurations, pure coconut fibre, pure kenaf fibre and three mixed ratios, under controlled airflow conditions, with and without Epipremnum aureum. System performance was evaluated based on single-pass removal efficiency (SPRE) for volatile organic compounds (VOCs), PM_2.5 and PM₁₀. Pure kenaf fibres achieved VOCs SPRE of 86.49% without plants and 87.13% with plants at elevated airflow rates. For PM₁₀, a 30:70 coconut–kenaf mixture demonstrated SPRE of 88.71% at medium airflow without plants, while pure coconut fibre attained SPRE of 85.70% at high airflow with plants. PM_2.5 removal employed a 50:50 coconut–kenaf mixture, achieving SPRE of 82.51% efficiency at low airflow without plants and 79.61% with plants. Overall, these findings highlight the importance of natural fibres and modified airflow in BIAB systems, with botanical elements primarily aiding VOCs removal at lower airflow rates.