Determining biomethane potential from animal-source industry wastes by anaerobic digestion: A case study from La rioja, Spain

The animal-source food industry (ASFI) is currently facing important challenges derived from sustainability policies and market requirements. In this respect, the ecological footprint resulting from emissions, management of residues, effluents, and by-products has become a key factor not only due to the laws in force, but also from the point of view of operation efficiency and market requirements. This paper assesses the potential use of the organic wastes generated by the ASFI as a source of biofuel generation (i.e., biomethane) in the region of La Rioja (Spain). To this end, primary data were directly collected from factories and the so-produced wastes were sampled and characterized. Statistical inference from collected data leads to theoretically estimate that the region might produce up to 118.46 GWh per year, mainly provided from piggeries, which would replace 12.4 % of the natural gas used by the regional industry. Besides, this strategy also reduces the environmental footprint and the generation of added value for companies and rural localities. However, the analytics show that an excess of nitrogen content may hinder the calculated theoretical methane yields and lead to operational issues. Looking for biowaste from vegetable sources more optimal admixtures may be designed to address these concerns.