Opportunities and Challenges for Anaerobic Digestion of Farm Dairy Effluent

The current non-circular and non-regenerative approaches to farm dairy waste management have spurred a search for alternatives. Anaerobic digestion of the waste to collect biogas and digestate products is an option with significant potential for reducing the farm's environmental footprint and generating additional revenue. Although much research exists on the anaerobic digestion of dairy manure, there is a lack of detailed understanding of the challenges faced with farm dairy effluent (FDE). In addition, most existing studies lack key data, such as the on-farm process cost. Therefore, the main aim of this review is to highlight these challenges and offer new insights into possible state-of-the-art solutions The conventional methods of FDE disposal are critically compared to anaerobic digestion for economic, environmental, and technical feasibility. The paper also extends into a case study where a preliminary techno-economic assessment showed that in New Zealand, $2.3 million would be required to set up a farm anaerobic digestion plant with a 900-cow capacity. This information can aid decision-making on policies for farm technologies.