The article describes a pilot study on a wastewater treatment plant operating a biogas plant (2.793 MW). The authors of the
experiment used organic waste material, including: chicken fat with feathers (FF), molasses (M), glycerol (GL), raw sewage sludge
(SS) and digested sewage sludge as an inoculum. The parameters of raw and digested sludge were compared, e.g. changes in the
concentrations of ammonium nitrogen (N-NH4+), alkalinities, chemical oxygen demand (COD) and light metal ions. Potential
biodegradation pathways for the organic waste used in the experiments were also proposed. The proposed sequences of chemical
reactions are a useful tool for further biochemical analyses and for the mathematical modeling of anaerobic digestion.
The results showed that fat with feathers was the most valuable high-energy substrate as it gave a cumulative methane yield of 822
m3/mg VS (VS – volatile solids). There were comparable values of cumulative methane yield from molasses (350 m3/mg VS) and
glycerol (342 m3/mg VS), whereas sewage sludge gave the lowest yield (246 m3/mg VS).