A comparative study for destruction of n-hexane in Trickle Bed Air Biofilters

Abstract

Trickle Bed Air Biofilter (TBAB) could be an attractive treatment option for removal of hydrophobic Volatile Organic Compounds (VOCs) from air streams. In this study, three independent parallel laboratory-scale TBABs were run simultaneously to degrade n-hexane, a hydrophobic VOC known to be difficult to degrade. The loading rate of n-hexane varied from 13.4 and 47.7 g/(m 3 h) (1.14–4.04 kg COD/(m 3 day)). The experimental plan was designed to operate one TBAB at pH 7, another at pH 7 utilizing surfactant for enhancing the solubility of n-hexane, and finally a third one operating at pH 4 to promote fungi growth. Elimination capacities up to 38.7 g/(m 3 h) (3.28 kg COD/(m 3 day)) were observed with a removal efficiency of 90% for the TBAB operating at pH 4. The operating conditions for the TBABs include 120 s of Empty Bed Residence Time (EBRT), 1.4 L/min air flow rate and fixed temperature of 20 °C. Biomass control within the TBAB was investigated through two strategies, namely, stagnation (off flow for 2 days/week) and flow switching.