The effect of clogging on the long-term stability of different carbon fiber brushes in microbial fuel cells for brewery wastewater treatment

Carbon fiber brushes are widely used as anode electrode in microbial fuel cells (MFC) due to their good scalability and immense surface area. Clogging of fibers reduces the anode surface accessible for microorganisms resulting in a decreased power output of MFCs. Thus, usage of one brush with 10 cm in diameter (B1) was compared to usage of two brushes with 5 cm in diameter (B2) in a long-term-study, which was investigated in a 1 l single-chamber MFC for treatment of brewery wastewater. Despite half the theoretical surface area, the MFC with configuration B2 continuously achieved more than twice the power density compared to the MFC with configuration B1. Consequently, reducing the brush diameter and using 300 μm thick fibers results in a large active surface area by minimizing fiber clogging, which has been identified as the main factor in reducing power density.