## 4 Conclusions  
In this study, 52 microbial strains (sequenced 16S rRNA genes) were isolated from pig manure and screened to identify NH\({}_{3}\)-degrading microbes. Three strains were selected for odor reduction: _Saccharomyces cerevisiae_ NRRL Y-12632\({}^{\text{T}}\) (99.88%; TP1), _Lactococcus lactis_  
Figure 4: Change in NH\({}_{3}\) concentration emitted from swine manure in the open reactor: control (no treatment, only manure), foam alone (application of surfactant foam only), and bio foam (surfactant foam containing bacteria). The initial NH\({}_{3}\) concentration in the manure was 450 ppm. subsp. _hordniae_ NBRC 100931T (99.93%; TP3), and _Lactiplantiobacillus argentoratensis_ DSM 16365T (100%; TP5). This study found that all NH\({}_{3}\) was removed by the microbial consortium (1:1:1) after 48 h, while the control contained 60 ppm. This study also determined the surfactant and foam stabilizer concentrations to obtain long-lasting foam, where the optimal concentrations of AOS and gelatin were 0.2% and 0.3%, respectively, resulting in a foam half-life of 2 h.  
In this study, surface foam created a physical canopy that trapped the released odor gases from the emission source. Surfactant foam cover successfully reduced the NH\({}_{3}\) concentration in the environment by 97-100% (100% for open reactor and 97% for closed reactor). However, as the foam broke after 6 h, NH\({}_{3}\) was re-emitted from the NH\({}_{3}\) soil and swine manure. The bio-foam (NH\({}_{3}\) degrading bacteria-loaded foam) applied to the same NH\({}_{3}\) emission source also physically prevented the release of NH\({}_{3}\), and NH\({}_{3}\) was gradually re-emitted after foam breaking until 25 h. However, after 25 h, the degradation of NH\({}_{3}\) by bacteria (biodegradation) was dominant, and NH\({}_{3}\) degradation was completed after 72 h in NH\({}_{3}\) soil. In the real swine manure, the \"bio-foam\"-treated swine manure significantly reduced NH\({}_{3}\) emission even after foam breaking, which reduced to 10 and 0 ppm after 24 and 48 h, respectively. Surface foam spraying completely prevented the emission of malodorous gases, and a significant decrease in gas concentration (90-100% efficiency) was achieved after foam breaking, within two days. In future, the results of this laboratory study can help in the possible field extension of this research. The following are available online at [[https://www.mdpi.com/article/10.3390/app12041806/s1](https://www.mdpi.com/article/10.3390/app12041806/s1)]([https://www.mdpi.com/article/10.3390/app12041806/s1](https://www.mdpi.com/article/10.3390/app12041806/s1)), Text S1: Measurement of soil characteristics. Text S2: Reagent and materials. Table S1: Degradation of NH\({}_{3}\) by different microbial strains. Table S2: Degradation of NH\({}_{3}\) in the capped jar (conducted at 22 \({}^{\circ}\)C). Table S3: Degradation of NH\({}_{3}\) in the capped jar (conducted at 30 \({}^{\circ}\)C). Figure S1: Laboratory odor reduction test; (A) experimental set-up using soil/swine manure in the polystyrene box; (B) initial sampling before foam spraying; (C) initial NH\({}_{3}\) concentration (pink color changed to yellow); (D) covering the manure with surfactant foam spraying technology; (E) sampling after foam spraying; and (F) NH\({}_{3}\) concentration after foam spraying or final sampling (no change in pink color, 0 ppm). Figure S2: Effect of (A) AOS concentration and (B) AOS + gelatin concentration on foam stability (half-life). Conceptualization, J.K. and S.-W.J. ; methodology, R.B., P.G., T.T.N.L. and R.H.D. ; validation, R.B., P.G. and S.-W.J. ; resources, S.-W.J. ; writing--original draft preparation, R.B., P.G., T.T.N.L. and R.H.D. ; writing--review and editing, J.K. and S.-W.J. ; visualization, R.B. and P.G. ; supervision, J.K. and S.-W.J. ; project administration, J.K. and S.-W.J. ; funding acquisition, S.-W.J. All authors have read and agreed to the published version of the manuscript.