Upcycling agro-waste into sustainable bioenergy: using carbonized cabbage core wastes bio-anodes and novel bacterial insights in MFCs for sugarcane wastewater treatment

Abstract

In pursuit of sustainable energy and waste valorization, this study introduces a novel bio-anode synthesized from carbonized cabbage core waste, a low-cost, abundant agricultural byproduct engineered for high-performance microbial fuel cells (MFCs) utilizing sugarcane wastewater as a bio-electrochemical substrate. Carbonization at moderate temperatures yielded a porous, honeycomb-like carbon architecture conducive to microbial attachment, as confirmed via scanning electron microscopy (SEM). X-ray diffraction (XRD) revealed partial graphitization within a disordered matrix, optimizing conductivity while maintaining structural porosity. When applied in a dual-chamber MFC, the cabbage-derived bio-anode achieved a remarkable power density of 904.1 mW/m², exceeding that of conventional carbon felt by over 21-fold, alongside a maximum open-circuit voltage (OCV) of 822.4 ± 5.2 mV (2.33× increase). Critically, microbial analysis of the biofilm revealed a dominant presence of Exiguobacterium, marking the uniqueness of Exiguobacterium aurantiacum associated with anode biofilm during sugarcane-wastewater-driven MFC operation. Its tolerance to high-sugar environments and its putative role in extracellular electron transfer (EET) expand the known spectrum of bioelectrogenic species and introduce new possibilities for strain engineering in bioenergy research. This integrated approach exemplifies circular economy principles, converting agricultural and agro-industrial waste into clean electricity while advancing decentralized wastewater treatment. The outcomes of this work support multiple UN Sustainable Development Goals: including SDG 6 (Clean Water and Sanitation), SDG 7 (Affordable and Clean Energy), SDG 12 (Responsible Consumption and Production), and SDG 13 (Climate Action). By coupling waste-derived electrode materials with novel microbial pathways, this research advances the development of low-cost, scalable bioenergy systems for sustainable rural and industrial applications.