Abstract

Kombucha is a traditional fermented tea rich in organic acids and shows potential as a carbon source for Shewanella species to generate electricity in microbial fuel cells (MFCs). This research investigated the applicability of kombucha post-fermentation medium as a substrate to support the growth of Shewanella putrefaciens and electricity generation in recirculating MFCs. A preliminary growth study showed that S. putrefaciens could proliferate by utilizing organic acids present in 21-day-old kombucha at various concentrations. Inoculating recirculating dual-chamber MFCs with kombucha tea improved power production compared to the no-inoculum control, with recirculation yielding a power density of 756 mW m⁻² and a current density of 4160 mA m⁻². This study demonstrates the feasibility of using kombucha fermentation medium as a novel, sustainable substrate for S. putrefaciens and for recirculating MFCs, highlighting the potential of fermented food and beverage wastes for bioelectrochemical energy recovery.

Graphical abstract