Biogas potential from apple waste

Abstract

Biogas production can be used to recover energy from wet organic waste such as food industry residues. In this study, residues from apple juice production at the Epleblomsten juice production plant (Norway) are analyzed to determine the biogas potential.
A series of batch experiments with different initial feed concentrations (0, 1, 2, 5 and I 0%) of the leachate from the apple residues are carried out to find the total biogas potential and to investigate the composition of the leachate. These experiments were also simulated by the ADM I (Anaerobic digestion model No. I) in Aquasim as a method to estimate the chemical composition of the leachate.

According to the batch experimental data together with the simulation results it was estimated that the leachate organic matter consisted mainly of sugar and some organic acids. The estimated concentrations were used in a follow-up study to design and simulate a full scale process. The initial feed concentrations of I and 2% gave high biogas yields, while 5 and I 0% caused an overload and relatively low biogas yields. The biogas production potential was measured as the volume of biogas produced per I L feed consumed. There is no significant relationship between the residue leachate content and the gas compositions. The COD content of the feed was calculated to be about 160 g COD/L.