Two Liquid Phase Biofiltration for Removal of n -Hexane from Polluted Air

Abstract

Two equal-size biofilters with perlite as the packing material were used to investigate the effect of amending silicone oil to the bed of a biofilter for removal of n-hexane from a contaminated air stream. The bed particles of one of the biofilters were partially coated with silicone oil. An n-hexane degrading bacterial culture was used as a biocatalyst in both biofilters. The biofilters operated in parallel under the same conditions for 70 days. The results showed that the silicone oil amended biofilter performed better than the other consistently during the period of investigation. The maximum elimination capacity for the silicone oil amended biofilter was 167 g · m⁻³ _bed · h⁻¹ compared to 114.9 g · m⁻³ _bed · h⁻¹ for the control biofilter. Sorption capacity of a biofilter plays an important role in damping shock changes at entering concentration. To determine how the amended oil could affect the sorption capacity of the biofilter, the responses of the biofilters to step and pulse changes at the inlet concentrations were investigated. A new steady state was established within several minutes after a change at the inlet concentrations. The outlet concentrations of the biofilters increased almost in parallel after a step increase at the inlet concentrations. For a step decrease at the inlet concentrations, the outlet concentration of the oil-amended biofilter was higher than the other for a short period of time due to the desorption phenomenon. The oil-amended biofilter damped a pulse increase at the inlet concentration much more effective than the control biofilter.