Performance and mechanism study of semi-continuous operation of kitchen waste treatment system with microbially reduced graphene oxide modified microbial fuel cell electrodes
In response to the long-term treatment of kitchen waste, a Microbial fuel cell (MFC) reactor with a microbially reduced graphene oxide (MRGO) modified anode, prepared using the best strategy, was constructed to explore the impact of MRGO and different residence times of kitchen waste (5, 10, and 15 days) on the performance, resource recovery, and stability of the reactor in handling kitchen waste. The results indicated that the stable output voltage of the MRGO modified MFC anode was approximately 26 times that of the biomodified MFC anode, and the proportion of high even-carbon VFAs (C3H7COOH + C5H11COOH) to influent total chemical oxygen demand (TCOD) was about 1.4 times that of the biomodified MFC anode. Furthermore, a 10-day residence time was identified as the optimal for the MRGO modified MFC anode system in handling kitchen waste. The MRGO modification enhanced the activity of electrogenic bacteria in the anodic biofilm and the transcriptional activity of genes related to electricity production and carbon chain elongation, revealing the microbial mechanism by which MRGO enhances electrical performance. The transcriptional level differences in functional genes among the three MRGO modified MFC anode biofilms were minimal, further elucidating the microbial mechanism that MRGO's enhancement of MFC performance is stronger than the regulatory effect of residence time, proving that MRGO modified MFC anodes improve the stability of kitchen waste treatment systems. Therefore, MRGO modified MFC anodes have the potential to achieve the goal of kitchen waste resource utilisation.