Improving NH and HS removal efficiency with pilot-scale biotrickling filter by co-immobilizing Kosakonia oryzae FB2-3 and Acinetobacter baumannii L5-4.

In this study, two NH-N and S removal strains, namely, Kosakonia oryzae (FB2-3) and Acinetobacter baumannii (L5-4), were isolated from the packing materials in a long-running biotrickling filter (BTF). The removal capacities of combined FB2-3 and L5-4 (FB2-3 + L5-4) toward 100 mg L of NH-N and 200 mg L of S reached 97.31 ± 1.62% and 98.57 ± 1.12% under the optimal conditions (32.0 °C and initial pH = 7.0), which were higher than those of single strain. Then, FB2-3 and L5-4 liquid inoculums were prepared, and their concentrations respectively reached 1.56 × 10 CFU mL and 1.05 × 10 CFU mL by adding different resuspension solutions and protective agents after 12-week storage at 25 °C. Finally, pilot-scale BTF test showed that NH and HS in the real exhaust gases from a pharmaceutical factory were effectively removed with removal rates > 87% and maximum elimination capacities were reached 136 g (NH) m h and 176 g (HS) m h at 18 °C-34 °C and pH 4.0-7.0 in the BTF loaded with bamboo charcoal packing materials co-immobilized with FB2-3 and L5-4. After co-immobilization of FB2-3 and L5-4, in the bamboo charcoal packing materials, the new microbial diversity composition contained the dominant genera of Acinetobacter, Mycobacterium, Kosakonia, and Sulfobacillus was formed, and the diversity of entire bacterial community was decreased, compared to the control. These results indicate that FB2-3 and L5-4 have potential to be developed into liquid ready-to-use inoculums for effectively removing NH and HS from exhaust gases in BTF.