Quantification of CH₄ and N₂O Fluxes from Piggery Wastewater Treatment System for Emission Factors Development

Piggery farming is the largest source of livestock manure in South Korea, generating about 40% of total livestock waste annually. Yet greenhouse gas (GHG) emission data from piggery wastewater treatment systems remain limited, with most studies focused on farm slurry storage rather than process-level emissions. This study quantified methane (CH₄) and nitrous oxide (N₂O) fluxes from a full-scale piggery wastewater treatment facility in, to develop process, season, specific and diurnal specific emission fluxes. Continuous monitoring with a laser-based gas analyzer and customized PVC air-pool chamber was conducted across raw, anaerobic, and aerobic wastewater treatment stages. Mean CH₄ fluxes ranged 1.1-15.6 mg s⁻¹ m⁻², peaking in summer, while N₂O fluxes ranged 0.01-17971 mg s⁻¹ m⁻², with maxima in fall. Aeration tank II and Anaerobic tank I were the dominant emission stages, with night and intra-day peaks. Statistical analysis identified treatment stage and temperature as the main controls on CH₄ variability (p = 0.006 to 0.014), whereas N₂O showed weaker climatic sensitivity. The results provide refined emission factors and emphasize that aeration optimization and denitrification control are key to reducing GHG emissions from livestock wastewater systems in warm, humid regions.