Long-term investigation of microbial fuel cells treating primary sludge or digested sludge

- Two 1.8-L MFCs were operated on sewage sludge for almost 500 days.
- The MFCs achieved better treatment of primary sludge than digested sludge.
- Biogas production was produced from primary sludge and quantified.
- Total energy production in MFCs could be comparable to anaerobic digesters.
- Direct electricity generation had a minor contribution to total energy production.