Rapid optimization of 3D printed sediment microbial fuel cells

Sediment microbial fuel cells (SMFCs) are promising sustainable technologies for their ability to remediate sediment while converting waste into usable energy. While SMFCs are low-cost and easily constructed, they have not been widely adopted because unoptimized SMFCs exhibit low power densities. This work used additive manufacturing (AM), commonly called 3D printing, to facilitate the optimization of SMFCs for maximum bioelectricity generation. Various SMFC parameters, including sediment moisture, the presence of a water layer, the use of a proton exchange membrane (PEM), and electrode separation, are investigated using SMFCs designed for reliable and rapid testing. Daily rehydration was critical for stable bioelectric output, with higher moisture content increasing power density by as much as 150%. SMFCs with no water layer between the sediment and cathode exhibited significantly lower internal resistances that increased power density by 72-134%. The PEM increased power density by approximately 3% but made the SMFC more susceptible to dehydration. Shortening the electrode separation distance from 53 to 33 mm decreased internal resistance and the proton diffusion distance, resulting in the highest areal and volumetric power densities. The champion SMFC exhibited an average open-circuit voltage of 661 mV and a maximum areal and volumetric power density of 3.26 mW m(-2) and 98.9 mW m(-3).