Interactions and microbial variations in a biotrickling filter treating low concentrations of hydrogen sulfide and ammonia.

A lab-scale biotrickling filter (BTF) packed with porcelain Rasching ring and ceramsite was applied for co-treating of low concentrations of hydrogen sulfide (HS) and ammonia (NH), as major pollutants typically found in e.g., intensive livestock production facilities. In this study, the outlet gas concentrations of HS and NH were used for indicators if the treated gas reached odor-free condition. Overall, excellent removal efficiencies were obtained for both HS and NH in the BTF during Stage I (HS alone) and Stage II (HS and NH). Specifically, the HS outlet concentration was below the detection limit (∼3.6 ppbv) and the NH outlet concentration was less than 0.4 ppmv when the inlet concentrations of HS and NH were around 1.8 ppmv and 35.3 ppmv, respectively. In this case, the running empty bed residence time was 10.2 s. During Stage II, the outlet HS concentration was decreased significantly when the inlet NH concentration was increased, likely due to the influence by pH. Meanwhile, the outlet nitrous oxide (NO) concentration was kept low (<2% NH) during the experiment, suggesting a proper operation of the BTF. After the inlet gas shifted from HS alone at Stage I to HS and NH at Stage II, the main sulfur-oxidizing bacteria (SOB) species in the BTF switched from Acidithiobacillus to Thiobacillus.