Urban circular carbon economy through electrochemically influenced microbiomes

Food waste and wastewater are two of the largest carbon streams in urban systems and have huge potential in waste carbon valorization and carbon circularity, which are vital to achieving net-zero emissions goals. Conventional waste treatment practices, however, largely fail to realize the potential and often create additional socio-environmental externalities. Microbiome-based waste recovery, particularly electrochemically influenced processes like electrofermentation, emerges as a promising circular approach to convert waste food/water into valuable, carbon-negative products. However, difficulties and inconsistencies exist for civil-scale operation using mixed microbial communities. In this perspective, we propose a large-scale circular carbon food-water-energy framework using electrochemically engineered microbiomes in urban settings. By coupling food and water waste streams via co-digestion and biofilm-based treatment processes and regulating and upgrading anaerobic fermentation/digestion with low-cost renewable electricity, we present a promising roadmap of urban circular carbon economy with a net-zero process of food waste and wastewater treatment and value-added resource recovery.