Performance and biofilm characteristics of a gas biofilter for n-hexane removal at various operational conditions

Abstract

The effects of operational parameters including nitrate concentration, n-hexane inlet concentration and gas empty bed residence time (EBRT) on long-term removal performance of n-hexane were discussed. Biofilm characteristics over long-term operation in a gas biotrickling filter (BTF) were also investigated. The results showed that 160 mg L⁻¹ of N–NO₃⁻ was sufficient for n-hexane removal at a constant inlet concentration of 350 mg m⁻³ and gas EBRT of 30 s. With increasing inlet concentration and decreasing EBRT, the removal efficiency (RE) declined. The elimination capacity (EC) maximized at 45.36 g m⁻³ h⁻¹ for an inlet concentration of 900 mg m⁻³ and gas EBRT of 30 s. Proteins were the dominant component of EPS in biofilms for n-hexane removal in a gas biofilter. Protein concentration in the biofilms increased while the polysaccharide concentration changed slightly, therefore the total extracellular polymeric substance (EPS) concentration increased over time. The zeta potential of the biofilms became less negative due to an increase in protein concentration, indicating that the zeta potential could be used as an index of protein concentration in gas biofilters.