Styrene vapor biodegradation in single- and two-liquid phase biotrickling filters using Ralstonia eutropha

• Styrene vapor was removed from air using pure culture of Ralstonia eutropha.
• Single and two-liquid phase BTFs were used for styrene removal at 40 °C.
• ECmaxs of 70 and 110 g m−3 h−1 were obtained for single and two phase BTFs.
• Presence of oil appeared to alter the composition of the bacterial culture.
• Presence of oil decreased the effect of changing the temperature on performance.

This study examined the use of a bacterial culture of Ralstonia eutropha in biotrickling filters (BTFs) for styrene vapor removal in the absence and presence of silicone oil (5% v/v). Removal was carried out at 40 °C using styrene inlet concentrations of 0.8–3.3 g m−3 and empty bed residence times (EBRTs) of 1 and 2 min. For single-phase BTF, a removal efficiency (RE) of 95% was achieved at inlet concentrations of <2.5 g m−3 and at an EBRT of 1 min. The addition of oil to the recirculating solution enhanced styrene elimination under all operating conditions and increased maximum elimination capacity (ECmax) from 70 to 110 g m−3 h−1. Results of elemental analysis of microorganisms isolated from the bed of the BTFs and biodegradation equations showed that the ratios of CO2 generation to styrene consumption were 2.60 for single-phase and 4.85 for two-phase BTFs. A comparison of results at 35 °C and 40 °C showed that the presence of oil decreased the effect of operating temperature on RE.