Recovery of biogas as a source of renewable energy from ice-cream production residues and wastewater

Abstract

Proper management of waste streams and residues from agro-industry is very important to prevent environmental pollution. In particular, the anaerobic co-digestion process can be used as an important tool for safe disposal and energy recovery from agro-industry waste streams and residues. The primary objective of this laboratory-scale study was to determine whether it was possible to recover energy (biogas) from ice-cream production residues and wastewater, through a mesophilic anaerobic co-digestion process. A high methane yield of 0.338 L CH₄/g COD_removed could be achieved from anaerobic digestion of ice-cream wastewater alone, with almost 70% of methane in biogas, while anaerobic digestion of ice-cream production residue alone did not seem feasible. When wastewater and ice-cream production residue were anaerobically co-digested at a ratio of 9:1 by weight, the highest methane yield of 0.131 L CH₄/gCOD_removed was observed. Buffering capacity seemed to be imperative in energy recovery from these substrates in the anaerobic digestion process.

Keywords:

• anaerobic digestion
• biogas
• ice-cream production residues
• methane
• renewable energy

Acknowledgements

The authors thank Bogazici University Research Fund for supporting this work (Project numbers 12Y00P1 and 11Y00P3).