Biodegradation of styrene laden waste gas stream using a compost-based biofilter

Abstract Biological treatment of waste gas styrene vapor was investigated in a three-stage bench-scale biofilter. Yard waste compost mixed with shredded hard plastics in a 25:75 v/v ratio of plastics:compost was inoculated with thickened municipal activated sludge. Microbial acclimation to styrene was achieved by exposing the system to an inlet concentration ( C In ) of 0.25 g m −3 styrene and an empty bed retention time (EBRT) of 360 s for 30 days. Under steady-state conditions, maximum elimination capacity (EC) obtained was 45 g m −3  h −1 at a loading rate ( L ) of 60 g m −3  h −1 ( C In of 2 g m −3 and EBRT of 120 s). Reduction of retention time adversely impacted the performance resulting in the maximum EC of 39 and 27 g m −3  h −1 for EBRT of 60 and 30 s, respectively. Evaluation of the concentration profile along the bed height indicated dominance of first-order kinetics at C In  ⩽ 0.45 g m −3 and zero-order for higher concentrations.