Simultaneous Biofiltration of H2S, NH3and Toluene using an Inorganic/Polymeric Composite Carrier

Abstract

Simultaneous removal of ternary gases of NH3, H2S and toluene in a contaminated air stream was investigated over 180 days in a biofilter. A commercially available inorganic/polymeric composite chip with a large void volume (bed porosity > 0.80) was used as a microbial support. Multiple microorganisms including Nitrosomonas and Nitrobactor for nitrogen removal, Thiobacillus thioparus (ATCC 23645) for H2S removal and Pseudomonas aeruginosa (ATCC 15692), Pseudomonas putida (ATCC 17484) and Pseudomonas putida (ATCC 23973) for toluene removal were used simultaneously. The empty bed residence time (EBRT) ranged from 60 - 120 seconds and the inlet feed concentration was 0.0325 g/m 3 - 0.0651 g/m 3 for NH3, 0.0636 g/m 3 - 0.141 g/m 3 for H2S, and 0.0918 g/m 3 - 0.383 g/m 3 for toluene, respectively. The observed removal efficiency was 2% 98% for NH3, 2% - 100% for H2S, and 2% - 80% for toluene, respectively. Maximum elimination capacity was about 2.7 g/m 3 /hr for NH3, > 6.4 g/m 3 /hr for H2S and 4.0 g/m 3 /hr for toluene, respectively. The inorganic/polymeric composite carrier required 40 - 80 days of wetting time for biofilm formation due to the hydrophobic nature of the carrier. Once the surface of the carrier was completely wetted, the microbial activity became stable. During the long-term operation, pressure drop was negligible because the void volume of the carrier was two times higher than the conventional packing materials.