This study investigated the effectiveness of floating covers (FCs) in mitigating ammonia (NH₃) and hydrogen sulfide (H₂S) emissions from lab-scale swine slurry pits. Lab experiments were conducted over 125 days, comparing a treatment setup with FCs covering approximately 51.6% of the slurry surface to a control setup without covers. The results showed a significant reduction in NH₃ emissions by 54.4% with FCs (p < 0.05), which was attributed to their ability to limit NH₃ volatilization and promote crust formation. Although H₂S emissions were also reduced by 22.7%, this decrease was not statistically significant, likely due to the complex factors influencing H₂S production. These findings highlight the role of floating covers (FCs) in improving air quality within swine barns and reducing environmental pollution. By minimizing nitrogen loss as ammonia (NH₃), FCs enhance nitrogen recycling into agricultural land, supporting sustainable nutrient management. This aligns with broader sustainability goals by addressing air quality concerns, reducing odors, and improving resource efficiency in livestock systems. This study offers an effective method to mitigate air pollution, providing a foundation for practical and sustainable agricultural practices.

This study evaluated the impact of a ground channel ventilation system on seasonal ammonia emissions in a swine-finishing barn over three distinct seasons: summer, late autumn, and winter. The ground channel system tempered inlet air, cooling it during summer and warming it during colder seasons, maintaining stable room temperatures despite external fluctuations. During summer, the ground channel reduced the incoming air temperature from 26.9 °C to 22.5 °C, contributing to steady barn temperatures (28.0 °C) and mitigating ammonia emissions, which reached 111.0 ± 23.6 g day⁻¹ AU⁻¹. In late autumn and winter, it warmed the inlet air from 4.7 °C and −0.7 °C to 8.1 °C and 6.8 °C, respectively, maintaining stable room temperatures (25.1 °C and 24.3 °C). Ammonia emissions remained consistent across seasons, with 125.0 ± 37.3 g day⁻¹ AU⁻¹ in late autumn and 107.1 ± 20.5 g day⁻¹ AU⁻¹ in winter. Thus, ammonia emissions showed no seasonal differences, highlighting the system’s effectiveness in balancing ventilation rates with emissions. During late autumn and winter, it improved air quality without compromising thermal comfort for the swine. In summer, the reduced ventilation demand lowered ammonia emissions, supporting the effective management of ammonia emissions year-round. Future research should investigate the system’s effects on other gases and slurry pit temperatures.

This study evaluated the odor mitigation potential of rice husk biochar in a simulated dairy bedded pack over 21 days. Biochar was incorporated into a dairy manure–sawdust mixture at 5% and 10% dry weight. Emissions of key odorous compounds—ammonia (NH₃), sulfur compounds, volatile fatty acids, phenol, p-cresol, and indole—were evaluated. Odor units were assessed to determine perceived odor reduction. Biochar significantly reduced NH₃ and dimethyl sulfide (DMS) emissions: NH₃ by 27% and 43%, and DMS by 53% and 75%, at 5% and 10% application, respectively. The NH₃ reduction was attributed to ammoniacal nitrogen adsorption, while the DMS reduction likely resulted from enhanced air permeability suppressing anaerobic bacterial activity. The 5% biochar treatment, achieving 63% and 70% of the NH₃ and DMS reductions attained by the 10% treatment, respectively, offers a more practical and cost-effective option. Other odorous compounds were not significantly affected. A temporary reduction in odor units was observed on day 7. Rice husk biochar contains 14.5% atomic Si, primarily as silica, which supports structural stability but hinders pore development, reducing adsorption efficiency. These findings demonstrate the importance of biochar’s physicochemical properties in odor mitigation. Future research should evaluate long-term field performance, microbial interactions, and silica modification strategies.

Greenhouse gas (GHG) emissions are an unavoidable issue during manure composting. While soybean peroxidase (SBP), a low-value by-product of soybean processing, has been widely studied for odor mitigation, its potential to mitigate GHG emissions during composting remains poorly understood. To address this knowledge gap, this study investigated the effects of two SBP application strategies, single and split addition, on GHG emission reduction. The results indicate that SBP application helps prevent nitrogen loss and reduces CO2 emissions by 12–14%, CH4 emissions by 5–8%, and N2O emissions by 30–49%. As CO2 is a biogenic product, total GHGs calculated from CH4 and N2O are reduced by 26-39%. Microbial analysis emphasized the roles of nitrifying and denitrifying bacteria in influencing N2O emissions. Furthermore, ROS-related bacteria were observed, which likely influence the overall reduction in GHGs. Correlation heatmaps revealed relationships between environmental parameters and GHG emissions, highlighting the complexity and dynamics of the composting process. This study demonstrates that a single SBP addition is more effective than a split addition in mitigating GHG emissions, which may be due to the higher SBP addition on the initial day, leading to more stable and sustained chemical oxidation effects. Overall, this study suggests the potential of peroxidase-based additives, also present in other food by-products, as bio-based solutions for reducing GHG emissions.