Granular activated carbon tubular microbial fuel cell for decentralized greywater treatment

Abstract

This study developed a novel scalable tubular design of microbial fuel cells using granular activated carbon (GMFC). The GMFCs were tested over a year of batch-cycle operation for treating synthetic greywater and compared with aerated granular activated carbon biofilters (GBFs). The electrical performance of GMFCs with a non-aerated cathode presented a polarization shift along with high but unstable power densities, whereas, with the aerated cathode, the average power densities were stable. Direct microbial counting using epifluorescence and scanning electron microscopy revealed that GMFCs contain more sessile microorganisms than GBFs, suggesting that electrochemical systems favor biofilms. Ecological indices derived from community analysis suggested that GMFCs provide a less selective environment than GBFs and are more resilient to operation changes. The long-term operation, performance, and adsorption isotherm experiments suggested that the GMFC can use the organic matter adsorbed on the granules for bioregeneration without additional costs, leading to a robust long-term operation.