Biogas recovery by anaerobic digestion of Australian agro-industry waste: A review

On-farm, intensive feeding and processing in Australian red meat, dairy and pork industries produce substantial quantities of organic waste (∼79 GL·annum−1 liquid waste plus ∼2 megatonnes·annum−1 solid waste) and waste management is a major cost (∼180 million Australian dollars. annum−1 for red meat plus dairy processing). Anaerobic digestion can instead extract value from organic waste as biogas energy and biofertiliser to reduce operational costs and environmental impacts, and to improve industry profitability. Understanding key information gaps is a fundamental step towards fully realizing profitable opportunities for anaerobic digestion. This is addressed here via a critical evaluation of available information on Australian agro-industries (specifically dairy, pork and red meat), their waste availability, biogas energy potential, and potential anaerobic digestion approaches. The analysis revealed varying extents of information, but good biogas energy potential (∼13.8 PJ·annum−1) to meet a significant energy demand (∼18 PJ·annum−1). Waste management within respective agro-industries influenced waste amounts and characteristics, which affected anaerobic digestion options. Anaerobic co-digestion, involving aggregated digestion of two or more waste types within or across industries, can provide further opportunities by boosting biogas production and harnessing spare digestion capacity. Overall, cross-industry collaboration, policy support and technology development could help harness the significant opportunities for aggregated biogas production in Australian agro-industries.