Seasonal and daily emissions of methane and carbon dioxide from a pig wastewater storage system and the use of artificial vermiculite crusts

•Daily & seasonal GHG emissions measured in a full-scale pig wastewater storage system.•Overall emissions in winter were lower than in summer because of the low temperature.•Daily CH4 and CO2 emission fluxes depend on barn wastewater flushing operation.•Ability of vermiculite to reduce GHG emissions as artificial crust was verified.

There is insufficient knowledge of the seasonal and daily dynamics of greenhouse gas (GHG) emissions from preliminary storage tanks before anaerobic digestion as well as the reduction strategies required, particularly for full-scale cases. A full-scale three-stage wastewater storage tank system was investigated to quantify the dynamics of daily and seasonal GHG emission and the ability of vermiculite as artificial crust material to reduce GHG emissions. Overall CH4 and CO2 emissions in winter were approximately 8 g [CH4] m−2 h−1 and 3 g [CO2] m−2 h−1, respectively. These values were significantly lower than the 35 g [CH4] m−2 h−1 and g [CO2] m−2 h−1 values found in summer because of the lower temperatures. The daily fluctuations of CH4 and CO2 emission fluxes did not depend on the diurnal temperature changes, but on the barn wastewater flushing operation. The ability of vermiculite as artificial crust material to reduce GHG emissions on a full-scale pig wastewater storing system was verified. The overall reduction from the use of vermiculite, expressed as CO2 equivalent per year, was calculated to be 36.9% for summer and 17.1% for winter, indicating a useful potential application.