Fig. 3.

Illustration of microbial fuel cell (MFC). a) conventional MFC, where bacteria are electricigens to release electrons from organic matter (OM), b) photosynthetic-MFC (PMFC), where microalgae are electricigens to release electrons from photolysis, and c) microalgae-MFC (mMFC), where microalgae are biocathode by producing oxygen to reduce electron and release water. The diagrams show electrons are transported via external circuits and protons flow through a proton exchange membrane (PEM) to the cathode chambers to react with oxygen and electrons to produce water. The sketch was drawn based on the information provided by Saratale et al. [193].