Simultaneous removal of ammonia and hydrogen sulfide gases using biofilter media from the biodehydration stage and curing stage of composting.

Biofiltration of NH and HS with different packing media, biodehydration stage compost (BSC), and curing stage compost (CSC) was studied. Meanwhile, fluorescence excitation-emission matrix (EEM) spectroscopy was used to characterize the conversion mechanisms of organic matter during these biofiltration processes. Both biofilters were effective for the simultaneous removal of NH and HS when inlet concentrations of NH and HS were 0-50 and 50-250 mg/m, respectively. An abrupt increase in the inlet gas concentrations of NH and HS to 100-150 and 200-250 mg/m, respectively, caused the decrease in the removal efficiencies (REs) of NH and HS in the BSC biofilter, followed by a slow upturn. By contrast, relatively steady REs of both NH and HS were observed in the CSC biofilter. After 60 days of operation, the average REs of NH and HS were more than 95 % in the CSC biofilter. During the operation of CSC, nitrate and nitrite peaked around the 30th day, whereas sulfate showed a steady increase. The excitation-emission matrix fluorescence and parallel factor analysis (EEM-PARAFAC) indicated that the simultaneous inlet of NH and HS facilitated the degradation of protein-like substances, whereas humic-like substances played an important role in the packing filters for the treatment of the two odorous pollutants.