The role of biogas solutions for enhanced nutrient recovery in biobased industries—three case studies from different industrial sectors

Abstract This study analysed to what extent biogas solutions can improve the nutrient recovery of biobased industrial clusters in different sectors. Three cases representing the agricultural, marine and forest sectors were analysed quantitatively using mass flow analysis. Adding a biogas plant facilitated production expansion and development of collaborative waste management, e.g. a wheat processing biorefinery with a mill and agricultural actors, or a pulp and paper mill with the aquaculture industry. In the marine- and forest-based cases, this decreased the total nitrogen (N) and phosphorous (P) input by 18% while increasing the recovery rate; e.g. for P from 32 to 96% for the marine-based and from 52 to 91%, for the forest-based. The impact in the agro-based case was minor as the actors were already operating with a high nutrient recovery. For the marine-based case, the impact was due to a huge increase in P recovery for the aquaculture actor while for the forest-based case, N from the aquacultural sector could be reused in the wastewater treatment. For the agro- and marine-based cases, adding a biogas plant also resulted in less transports and more local nutrient recycling; the total transport of organic waste, by-products and biofertilizers (in km x tonne) was reduced by 40% and 90%, respectively. The results demonstrate that biogas solutions can stimulate the development of biobased industrial symbiosis with integrated waste management, and contribute to more efficient recycling of key resources, which is essential for the transition to a circular society.