Biogas from poultry waste—production and energy potential

The objective of this study was to evaluate the effect of heat treatment on poultry litter with different levels of reutilisation for potential generation of biogas in experimental biodigesters. Chicken litter used was obtained from two small-scale poultry houses where 14 birds m−2 were housed for a period of 42 days per cycle. Litter from aviary 1 received no heat treatment while each batch of litter produced from aviary 2 underwent a fermentation process. For each batch taken, two biodigesters were set for each aviary, with hydraulic retention time of 35 days. The efficiency of the biodigestion process was evaluated by biogas production in relation to total solids (TS) added, as well as the potential for power generation. Quantified volumes ranged from 8.9 to 41.1 L of biogas for aviary 1, and 6.7 to 33.9 L of biogas for aviary 2, with the sixth bed reused from both aviaries registering the largest biogas potential. Average potential biogas in m3 kg−1 of TS added were 0.022 to 0.034 for aviary 1 and 0.015 to 0.022 for aviary 2. Energy values ​​of biogas produced were calculated based on calorific value and ranged from 0.06 to 0.33 kWh for chicken litter without fermentation and from 0.05 to 0.27 kWh for chicken litter with fermentation. It was concluded that the re-use of poultry litter resulted in an increase in biogas production, and the use of fermentation in the microbiological treatment of poultry litter seems to have negatively influenced production of biogas.