Abstract: Four types of materials including activated carbon, lava, poly urethane foam and poly propylene ring were used as packings for biotrickling filters treating odor from a municipal waste water treatment plant. The performance, influence factors and pressure drops during the long-term operation were investigated. The experimental results show that at empty bed retention time of 20 s, 100% removal efficiencies for H₂S are achieved with four types of packing materials; 62.3% and 65.1% removal efficiencies for VOSC are achieved when packed with activated carbon and lava. The four contribution rates of reactors removal along the vertical height is mostly given by the part of 0-0.30 m, accounting for 56.6%, 40.0%, 38.4%, and 33.7%, respectively. Trickling liquid velosity of 0.011 m/h and pH of 5.4-7.3 are the best operation conditions for degradation; poly propylene ring is least affected by liquid trickling velocity, and lava presents higher resistance to low pH. When the backwashing is stopped, the removal efficiencies of activated carbon, lava, and poly urethane foam decline to 60%-80% in 220 days due to the low void fraction and small void diameter; otherwise, the removal efficiency of poly prylene ring maintains more than 95% because of the high void fration and large void diameter, showing stable removal performance during the long-term operation.