Long-term operation of a compost-based biofilter for biological removal of n-butyl acetate, p-xylene and ammonia gas from an air stream

An experimental study on the removal of the mixtures of n-butyl acetate (n-BA), p-xylene (p-XY) and ammonia gas (NH3) from an air stream was performed in a laboratory scale three-segment biofilter over a period of 4 months. The biofilter was packed with the mixture of mature pig compost, forest soil and a packing material made of polyethylene (PE) which was used in the moving bed biological reactor (MBBR) for treating wastewater. n-BA elimination capacities of 157 and 150 g m−3 h−1 were obtained at empty bed residence time (EBRT) of 60 and 30 s, respectively, corresponding to removal efficiency of approximate 100 and 96%. An approximate 100% removal of NH3 could be achieved with inlet concentration varying from 0.043 to 0.15 g m−3 at EBRT of 30 and 90 s. For p-XY, the maximal inlet concentration (0.51 g m−3) with removal efficiency of 100% at EBRT of 60 s was a little higher than 0.4 g m−3 at EBRT of 90 s due to NH3 feeding. The pH of the packing media varied in the neutral range (6.5–7.9) during the operation period. The results indicated that the mixtures of n-BA, p-XY and NH3 were successfully eliminated simultaneously in this biofilter.