A pilot-scale two-step biofilter system was evaluated in treating food waste composting emission for 220 days. Wood chips were packed at the bottom section while mixture of rock wool and earthworm compost (6% w/v) was packed at the top section. Inlet ammonia concentration was found to be dominant and intermittent. The overall ammonia removal of over 98% was achieved, 70% of which was removed in the wood chip section. The highest ammonia elimination capacity was determined to be 39.43 g-NH(3)/m(3)/h at 99.5% removal efficiency. From biodegradation kinetic analysis, the maximum removal rate, V(m), of the wood chip section was determined to be 200 g-NH(3)/m(3)/h and the saturation constant, K(s), 180 mg/m(3). For the rock wool-earthworm cast mixture section, the V(m) was 87 g-NH(3)/m(3)/h and K(s) was 87 mg/m(3). Complete removal of hydrogen sulfide and most trace compounds were achieved by the biofilter. Highest hydrogen sulfide elimination rate was 0.22 g-H(2)S/m(3)/h. The biofilter was optimized from 24 to 16 s EBRT with resulting low average pressure drops of 16 and 29 mm H(2)O/m, respectively.