In this work, a laboratory scale biofilter was design for removal of hydrogen sulphide packed with Thiobacillus thioparus immobilized in polyurethane foam particles (the initial immobilized biomass was 1.6×10 cel g of solid support). Three empty bed residence times (EBRT) were studied (100, 70 and 30 second) and the initial H2S concentration, ranging from 25 to 750 ppmv, in the inlet gas stream...