Isolation and Screening of Odor-Reducing Microbes from Swine Manure and Its Role in Reducing Ammonia Release in Combination with Surfactant Foam

Swine 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 NH3 release, and the aqueous-phase bacteria formed after foam breaking infiltrated in manure and degraded NH3. In this study, we first isolated NH3-degrading bacteria from swine manure. A bacterial consortium was prepared using the effective NH3-degrading strains Saccharomyces cerevisiae NRRL Y-12632 (99.88%) (TP1), Lactococcus lactis subsp. hordniae NBRC100931(T) (99.93%) (TP3), and Lactobacillus argentoratensis DSM 16365(T) (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 NH3-contaminated soil or real swine manure, which reduced the NH3 emission from the source (soil/manure) almost completely (97-100%), but NH3 was re-emitted after foam breaking (5 h: open reactor, 7 h: closed reactor). After loading the bacteria on the foam, the initial NH3 odor suppression was similar to that of the foam alone. However, NH3 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 NH3-contaminated soil, and 97.7% NH3 in the swine manure was reduced in 24 h. Furthermore, the reagent cost for preparing stable foam was reasonable, indicating its possible field extension.

Automated summary

The study developed a feasible bio-foam technology that effectively reduces ammonia emissions by using surfactant foam with bacteria to degrade ammonia. The results showed that the foam technology had a significant effect on reducing ammonia levels, and the cost of preparing stable foam was reasonable, indicating its potential for field applications.