Biodegradation of n -hexane as single pollutant and in a mixture with BTEX in a scoria/compost-based biofilter

Abstract

Abstract This study evaluated the biodegradation of n -hexane as single pollutant, and in a mixture with benzene, toluene, ethylbenzene, and xylenes (BTEX) in a scoria/compost-based biofilter. Initially, the biofilter was fed with n -hexane and maximum elimination capacities (EC max ) of 10.7 and 8.1 g m −3 h −1 were obtained for inlet loading rates (ILR) of 14.0 and 11.6 g m −3 h −1 at empty bed retention times (EBRT) of 138 and 108 s, respectively. Michaelis–Menten kinetic model was well fitted to the experimental EC of n -hexane in the single pollutant condition. In the presence of BTEX, the removal efficiency of n -hexane dramatically decreased from 76 to 21% at EBRT of 108 s. In this condition, BTEX was easily degraded with an EC max of 110.6 g m −3 h −1 for ILR of 119.1 g m −3 h −1 . A competitive inhibition kinetic well described the n -hexane removal in the presence of BTEX with an inhibition constant of 0.151 g m −3 . Moreover, the interaction index of benzene with the addition of BTEX was −0.702, indicating the significant inhibitory effect of BTEX on n -hexane biodegradation. This study revealed that, in the biofiltration of n -hexane/BTEX mixture, a significant decrease in BTEX concentration is a prerequisite for the efficient removal of n -hexane.