Anaerobic digestion as a core process for sustainable energy production in the soybean biorefinery: A techno‐economic assessment

With the ever-growing environmental concern about natural resources depletion and the search for alternative energy sources, anaerobic digestion technology emerges as a core process in biorefineries. One of the limiting factors for full-scale use of this process is the scarcity of studies that technically and economically evaluate more flexible and unconventional technologies, such as Anaerobic Sequencing Batch Biofilm Reactors (AnSBBR) with immobilized biomass. Therefore, this paper carried out a techno-economic evaluation regarding the implementation of AnSBBR reactors, on an industrial scale, in the treatment of soybean molasses and glycerin. The assessment was based on the best published results presented by this type of reactor on a laboratory scale. The scale-up estimate resulted in a configuration of 8 AnSBBR reactors with 1000 m³ each in the treatment of 59 tons-molasses⋅day⁻¹. The energy produced by this system could reach 18.6 GWh⋅year⁻¹ and would have an initial investment of USD 7.6 million with an annual return of USD 2.2 million. On treating 17 tons-glycerin⋅day⁻¹, the estimate resulted in a configuration of 6 AnSBBR reactors with 900 m³ each. The energy produced could reach 6.3 GWh⋅year⁻¹ and would have an initial investment of USD 5.8 million with an annual return of USD 1 million.