Optimization of microbial fuel cell performance application to high sulfide industrial wastewater treatment by modulating microbial function

Microbial fuel cells (MFCs) are innovative eco-friendly technologies that advance a circular
economy by enabling the conversion of both organic and inorganic substances in wastewater
to electricity. While conceptually promising, there are lingering questions regarding the
performance and stability of MFCs in real industrial settings. To address this research gap,
we investigated the influence of specific operational settings, regarding the hydraulic retention
time (HRT) and organic loading rate (OLR) on the performance of MFCs used for treating
sulfide-rich wastewater from a canned pineapple factory. Experiments were performed
at varying hydraulic retention times (2 days and 4 days) during both low and high seasonal
production. Through optimization, we achieved a current density generation of 47±15 mA/
m2, a COD removal efficiency of 91±9%, and a sulfide removal efficiency of 86±10%. Microbiome
analysis revealed improved MFC performance when there was a substantial presence
of electrogenic bacteria, sulfide-oxidizing bacteria, and methanotrophs, alongside a
reduced abundance of sulfate-reducing bacteria and methanogens. In conclusion, we recommend
the following operational guidelines for applying MFCs in industrial wastewater
treatment: (i) Careful selection of the microbial inoculum, as this step significantly influences
the composition of the MFC microbial community and its overall performance. (ii) Initiating
MFC operation with an appropriate OLR is essential. This helps in establishing an effective
and adaptable microbial community within the MFCs, which can be beneficial when facing
variations in OLR due to seasonal production changes. (iii) Identifying and maintaining
MFC-supporting microbes, including those identified in this study, should be a priority.  Keeping these microbes as an integral part of the system’s microbial composition throughout
the operation enhances and stabilizes MFC performance.