Aeration of pig slurry affects ammonia and greenhouse gases emissions

Abstract

Manure management is considered to be a main key for mitigating gas emissions from livestock buildings. Since there are a number of limitations that make it difficult to identify these conditions in farm-scale experiments, these experiments should be conducted on a laboratory scale. Therefore, the aim of this study was to develop pilot reactors for simulating the operation conditions to be used later in a farm-scale experiment. The developed reactors were made from polyvinylchloride with 1.5 m height and 0.16 m diameter to be filled with 0.19 L slurry. The generated concentrations of NH₃, N₂O and CH₄ from the slurry were continuously analysed at 800 mL min⁻¹ air flow rate using three different sampling methods. The concentration gradient was also analysed within gas chamber height above the slurry. No differences were apparent neither between the various sampling methods nor concentrations gradient in the gas chamber. Acid pilot reactor was developed to determine the required acid concentration and quantity. Influences of pH slurry and air flow rates on gases concentrations were investigated. At 0.32 ${\text{m}}_{\text{air}}^{3} \;{\text{m}}_{\text{slurry}}^{ - 3} \;{\text{h}}^{ - 1}$ flow rate, the reproducible value of the emissions was minimized. The emissions of NH₃, N₂O and CH₄ were 3.2, 2.3 and 38 ${\text{mg}}\;{\text{m}}_{\text{slurry}}^{ - 3} \;{\text{h}}^{ - 1}$, respectively. In order to achieve minimum gas emissions under aerobic conditions, slurry pH should be kept in the neutral range. A comparison of gas emissions under aerobic and anaerobic conditions was conducted. Approximately 70% less NH₃ and 130% more N₂O were produced under aerobic than with anaerobic conditions.