Influence of biological pretreatment of poultry manure on biochemical methane potential and ammonia emission

Poultry manure has great potential for renewable energy utilization in biogas production. However, extremely high levels of nitrogen lead to unstable conditions in the anaerobic process, including the accumulation of intermediates, such as ammonia, which reduces the biogas production and the quality of the biogas. For this reason, additional measures are needed to ensure the proper management of poultry manure in anaerobic systems. This study evaluated the effect of primary biological treatment of poultry manure on biochemical methane potential (CH4) and reduction of ammonia (NH3) emissions. The results obtained when evaluating the biochemical methane potential from the digestate revealed that the biological additives selected for the study did not significantly influence the biochemical methane potential. After considering the differences of dry organic matter, it was found that maintaining optimum conditions and using biological additives during pretreatment increases the biochemical methane potential from 11.00 to 89.94 L CH4/kg volatile solids (VS). Biological pretreatment of poultry manure has a positive effect on biogas composition: methane concentration increases by 6.3-10.4% after pretreatment, and impurities such as hydrogen sulphide (H2S) decrease by 1.1-17.4 times. Ammonia emissions from all treatments of poultry manure were higher than those from untreated poultry manure, as measured by the evaporation rate of NH3. However, when measuring the evaporation rate of NH3 from the digestate, it was found that NH3 emission rates showed similar trends.