###### Abstract  
Swing farming facilities have increased the production of malodorous gases, which negatively affects people. Hence, we developed a new feasible bio-foam technology wherein long-lasting surfactant foam, including bacteria, were sprayed on swine manure. The surfactant foam acted as a physical barrier, suppressing NH\({}_{3}\) release, and the aqueous-phase bacteria formed after foam breaking infiltrated in manure and degraded NH\({}_{3}\). In this study, we first isolated NH\({}_{3}\)-degrading bacteria from swine manure. A bacterial consortium was prepared using the effective NH\({}_{3}\)-degrading strains _Saccharomyces cerevisiae_ NRRL Y-12632 (99.88%) (TP1), _Lactococcus lactis_ subsp. _Indariae_ NBRC100931T (99.93%) (TP3), and _Lactobacillus argentoraterasis_ DSM 16365T (100%) (TP5). The surfactant foam used in this study was a dry foam (foam quality 98.5-99.0% and foam density 0.025-0.026 g/cm\({}^{3}\)), with a foam expansion of 110-112 and high foamability. Large bubbles were generated with a bubble density of 1 bubble/cm\({}^{2}\) and a foam lamella thickness of 0.12 mm. In a lab-scale study, foam was sprayed onto NH\({}_{3}\)-contaminated soil or real swine manure, which reduced the NH\({}_{3}\) emission from the source (soil/ manure) almost completely (97-100%), but NH\({}_{3}\) was re-emitted after foam breaking (5 h: open reactor, 7 h: closed reactor). After loading the bacteria on the foam, the initial NH\({}_{3}\) odor suppression was similar to that of the foam alone. However, NH\({}_{3}\) was effectively reduced by microbial degradation even after foam breaking. Complete odor degradation was observed after 3 days (72 h; 90-100% reduction) for the NH\({}_{3}\)-contaminated soil, and 97.7% NH\({}_{3}\) in the swine manure was reduced in 24 h. Furthermore, the reagent cost for preparing stable foam was reasonable, indicating its possible field extension. malodor; surfactant foam; odor suppression; bio-degradation; feasibility; infiltration; surfactant; stability; surface tension; foam application; foam cover technology +
Footnote †: journal: Applied  
unconsciousness, and even death [6; 7; 8; 9]. Hence, there is an urgent need to prevent malodors, which has become a serious public health concern worldwide [10]. In recent years, many innovative strategies have been made available to farmers to manage the odors emitted from livestock manure. These technologies can be categorized as physical, chemical, or biological odor control technologies [8]. Some well-established physical technologies are the adsorption, masking, and dilution of the gases emitted from facilities. The former technology, adsorption and masking, is expensive, and the latter involves the process of diluting air, wherein malodorous gases from manure are diluted by adding other gases such as camphor and indole-coumarin. These physical-based technologies are extremely useful for treating low concentrations of gases produced from manure, but appear to be ineffective for high concentrations [11; 12]. Chemical methods of odor reduction include plant wet scrubbing, photocatalytic oxidation, extract spraying, combustion, and non-thermal plasma [13; 14; 15]. These chemical technologies are effective, with a removal rate greater than 90%. However, odor control by these technologies is only efficiently achieved after all odorous gases are appropriately collected from the odor source and introduced into the chemical system [16; 17; 18; 19]. Biological methods, however, use microorganisms to remove odors. They have little or no chance of producing secondary pollution from the facilities and exhibit low energy consumption [20]. Biofiltration, bio-trickling, and bio-scrubbing are the most commonly used biological treatments in the literature. These are mostly ex situ treatments (extraction from the source and treatment using a specially designed technology) performed by designing special instruments, whereas in situ treatment (treatment on-site) for odor removal remains a challenging task for experts.