Biogas production from chicken manure at different organic loading rates in a mesophilic full scale anaerobic digestion plant

The objective of this work was to determine the potential of using chicken manure (CM) as a sole feedstock for renewable biogas production under anaerobic conditions before spreading the digested chicken manure biomass on the fields as an organic biofertilizer. The chicken manure samples from four different locations of Lithuania were analysed and compared in order to better understand the chemical composition of the locally generated biomass resource. The annual quantities of chicken manure produced were investigated allowing estimation of the biogas potential if such biomass was treated anaerobically. Laboratory biomethane potential (BMP) tests performed indicated the biogas potential of methane - 508 mL CH4 g(-1) VS added and this result was compared to biogas yields obtained in full scale anaerobic digestion plant using manure as a core substrate. Fermentation process data analysis of anaerobic digestion performance indicates that the system is able to adapt even if the same operational conditions, such as organic loading rate and retention time are applied. Once adapted, the performance of biogas plant fermenter was able to deliver 93% of chicken manure biogas potential with an OLR of 3.14 kg VS L(-1)d(-1) and TAN concentration of 5.5 g L-1. The results indicated that it is possible to digest chicken manure as a stand-alone feedstock if ammonium concentration was carefully controlled via optimized fresh water dilution process.