Environmental and economic advantages of production and application of digestate biochar

Abstract

It has been repeatedly and independently proved that biochar applications brings a wide range of environmental advantages. For these benefits to have any tangible impact on a global scale, biochar needs to be applied in substantial quantities. However, the commercial applicability of the most of the research to date is limited by demanding requirements for the biochar used (pricy feedstocks or activated in demanding ways). Nevertheless, such production alternatives increase production costs and thus undermine the financial sustainability of many biochar applications. In contrast, the production of biochar from digestate via waste heat (from methane combustion at a biogas plants) brings several synergies that make it possible to obtain biochar at low production costs and at a constant quality throughout the year. Techno-economic considerations above-reviewed literature indicates for the first time that this competitive advantage can be used for mass scale eutrophication prevention. Based on the synthesis of the reviewed literature, the review is accompanied by (1) a proposal for the digestate biochar activation and subsequent use in wastewater treatment plants and (2) a financial estimate, which indicates the profitability of the new application.