Efficient strategy for employing HN-AD bacterium enhanced biofilter reactors to remove NH and reduce secondary pollution.

Heterotrophic nitrification-aerobic denitrification (HN-AD) strain (Paracoccus denitrificans HY-1) was employed in this study to enhance the removal efficiency of NH in a biological trickling filter (BTF) reactor. The results demonstrated that inoculation with HY-1 and packed with bamboo charcoal as filler significantly improved the RE of NH in BTF, reaching 96.52 % under 27 s of empty bed residence time (EBRT) and 812.56 ppm of inlet gas concentration. Meanwhile, the titer of NH-N, NO-N, and NO-N in the circulating fluid were merely 8.52 mg/L, 5.14 mg/L, and 18.07 mg/L, respectively. Microbial community and metabolism analyses revealed that HY-1 have successfully colonized in the BTF, and the high expression of denitrification-related genes (nar, nap, nir, nor and nos) further confirmed that the inoculation of HY-1 greatly improved both nitrification and denitrification metabolism. Furthermore, the biofilter reactor inoculated with HY-1 was applied at a large-scale piggery and exhibited remarkable odor removal effect, in which 99.61 % of NH and 96.63 % of HS were completely eliminated. In general, the HN-AD bacterium could strengthen the performance of BTF reactor and reduce the secondary pollution of circulating fluid during bio-deodorization.