Table 2.

An overview of some common challenges encountered in conventional microbial fuel cell technology.

Main obstacles	Description	Reference
High internal resistance	The involvement of PEMs or separators between the anodic and cathodic chambers introduced additional resistance to proton transport.	[145,146]
Limited scalability	Scaling up dual-chamber MFCs is challenging due to the increased complexity and potential issues associated with maintaining the PEMs.	[111]
Low coulombic efficiency	The separation of anodic and cathodic chambers by PEM can lead to side reactions or electron losses, reducing the overall efficiency of electron transfer.	[144,147]
Low power density	MFCs currently have lower energy conversion efficiency due to electron losses by high internal resistance.	[141]
Maintenance and system complexity	MFCs require regular maintenance to prevent membrane fouling, electrode degradation and system failures.	[141]
Membrane fouling	PEMs in dual-chamber MFCs are susceptible to scaling or fouling attributed to the accumulation of biofilms, salts, or other contaminants, lowering the membrane permeability and hindering proton transport.	[144,147]
Slow startup and lag phase	MFCs often require a startup period for exoelectrogens or microbial colonization and biofilm formation, leading to a delay in power generation as low cell density is inefficient for electron transfer.	[148]