Effects of an Under-Floor Perforated Panel System on Ammonia Emission Dynamics and Nitrogen Mass Balance in a Laboratory-Scale Swine Slurry Pit

Ammonia (NH3) emissions from swine slurry pits are strongly influenced by nitrogen loading, slurry pH, and gas–liquid mass transfer. This study evaluated an acrylic polymethyl methacrylate (PMMA) perforated-panel system designed to retain fecal solids while allowing the liquid fraction to drain into the lower slurry pit. Triplicate 63.3-L reactors were operated for 45 days at 25 °C. Based on input-fraction calculations, the treatment reduced volatile solids (VS) and total nitrogen (TN) loading to the lower slurry pit by approximately 97% and 38%, respectively. Maximum total volatile fatty acid (TVFA) concentrations were 276.4 mg L−1 in the control and 28.9 mg L−1 in the treatment, with reduced acidification and higher slurry pH in the treatment. Ammonia emissions initially increased and peaked at 874 mg day−1 m−2 on day 17. From days 20–45, NH3 emission rates were 46.5% lower, on average, than those of the control, and a secondary exploratory phase-specific analysis indicated a treatment effect (p = 0.0003). However, cumulative NH3-N emissions did not differ significantly over 45 days (p = 0.499). Thus, the panel altered temporal NH3 emission dynamics but did not significantly reduce cumulative NH3-N loss. Because slurry supernatant was used rather than fresh urine, field-scale validation with fresh excreta and realistic ventilation conditions is required.