However, the use of separator also causes several problems. One
major constraint is a retarded transfer of proton from the anodic
chamber to the cathodic chamber (or cathode), which leads to
pH splitting, i.e., pH increase in the cathodic chamber and decrease
in the anodic chamber. This will lower the system stability and bioelectrochemical
performance (Gil et al., 2003; Rozendal et al.,
2006; Kim et al., 2007a). Another problem is that it increases the
overall internal resistance of an MFC (Harnisch and Schröder,
2009). In addition, it also increases the overall costs of an MFC.
Therefore, how to overcome these challenges is the highest priority
for the ongoing development of separators for MFCs