Biofiltration for ammonia removal from composting exhaust gases

A study was conducted to investigate the utilization of mature compost as a biofilter media for the removal of ammonia from the exhaust gases of the composting process. Source-selected organic fraction of municipal solid wastes, digested wastewater sludge and animal by-products were composted in a pilot-scale reactor and the exhaust gas was treated in a biofilter. Due to the high ammonia adsorption and absorption capacity of the compost media, no delay or start-up phase was observed and high removal efficiencies were achieved from the beginning of the experiments. A global ammonia removal efficiency of 95.9% was obtained in the biofilter for a loading rate range of 846-67,100 mg NH3 m−3 biofilter h−1. However, an important reduction of ammonia removal was observed when the waste gas contained high NH3 concentration (more than 2000 mg NH3 m−3), which corresponded with the case of animal by-products composting.