Enhancing the electricity generation and sludge reduction of sludge microbial fuel cell with graphene oxide and reduced graphene oxide

Sludge microbial fuel cell (SMFC) is capable of extracting biomass energy directly from the sludge while generating electricity. However, most of organic matters in the excess sludge are the cell substances that are difficult to be used by microorganism directly. In this paper, adding graphene oxide (GO) and reduced graphene oxide (rGO) in SMFC was proposed and their advantages were reflected by no requiring external energy, in-situ promoting the electricity production and reducing sludge effectively. The results showed that the contents of lactate dehydrogenase (LDH) for adding 0.4 g GO in SMFC (0.4-GO SMFC) and adding 0.4 g rGO in SMFC (0.4-rGO SMFC) were 2 and 1.81 times higher than that of adding nothing in SMFC (ordinary SMFC), respectively. The species and compositions of organic matter in 0.4-GO SMFC and 0.4-rGO SMFC decreased significantly and their sludge reduction rate were 3 and 2.2 times that of ordinary SMFC, respectively. Comparing with ordinary SMFC, the maximum power density of 0.4-GO SMFC and 0.4-rGO SMFC was up to 214.09 and 80.52 mW m−3 separately, and their internal resistance decreased by 71% and 48%, respectively. Thus, it can be concluded that GO and rGO had the function of breaking cell and accelerated electrons transporting, so they could greatly promote the sludge reduction and electricity production of SMFC.