The effects of leachate recycling and bed mixing on the removal rate of H2S from waste gas stream were investigated. The experimental setup consisted of an epoxy-coated three-section biofilter with an ID of 8 cm and effective bed height of 120 cm. Bed material consisted of municipal solid waste compost and PVC bits with an overall porosity of 54% and dry bulk density of 0.456 g cm(-3). Leachate recycling had a positive effect of increasing elimination capacity (EC) up to 21 g S m(-3) bed h(-1) at recycling rates of 75 ml d(-1), but in the bed mixing period EC declined to 8 g S m(-3) bed h(-1). Pressure drop had a range of zero to 18 mm H2O m(-1) in the course of leachate recycling. Accumulation of sulfur reduced removal efficiency and increased pressure drop up to 110 mm H2O m(-1) filter during the bed mixing stage. (C) 2012 Elsevier Ltd. All rights reserved.