Electricity Recovery from Municipal Sewage Wastewater Using a Hydrogel Complex Composed of Microbially Reduced Graphene Oxide and Sludge

Abstract

Graphene oxide (GO) has recently been shown to be an excellent anode substrate for exoelectrogens. This study demonstrates the applicability of GO in recovering electricity from sewage wastewater. Anaerobic incubation of sludge with GO formed a hydrogel complex that embeds microbial cells via π-π stacking of microbially reduced GO. The rGO complex was electrically conductive (23 mS·cm−1) and immediately produced electricity in sewage wastewater under polarization at +200 mV vs. Ag/AgCl. Higher and more stable production of electricity was observed with rGO complexes (179–310 μA·cm−3) than with graphite felt (GF; 79–95 μA·cm−3). Electrochemical analyses revealed that this finding was attributable to the greater capacitance and smaller internal resistance of the rGO complex. Microbial community analysis showed abundances of Geobacter species in both rGO and GF complexes, whereas more diverse candidate exoelectrogens in the Desulfarculaceae family and Geothrix genus were particularly prominent in the rGO complex.

On Site Evaluation of a Tubular Microbial Fuel Cell Using an Anion Exchange Membrane for Sewage Water Treatment

“…a mixture of 1.7 mg·cm −2 activated carbon (Wako, Tokyo, Japan), 1.1 mg·cm −2 of carbon black (Fuel Cell Earth, Woburn, MA, USA), 14 µL·cm −2 of isopropanol, 5.6 µL·cm −2 of 20% Poly (diallyldimethylammonium chloride) solution (SIGMA-ALDRICH, St. Louis, MO, USA), and 5.6 µL·cm −2 of 60% PTFE solution (SIGMA-ALDRICH). An AEM (ASTOM, Tokyo, Japan) was used as the separator while a graphite felt sheet, with a thickness of 0.5 cm, was used as the anode (Yoshida et al, 2016b). To collect electrons, a stainless steel mesh (Clever, Toyohashi, Japan) was used in both electrodes.…”

“…The three sets of electrodes in the module were individually polarized with an external resistance of 120 (0-7 days) and 27 (after 7 days). The voltage was measured every hour as described previously (Yoshida et al, 2016b).…”

Bioinspired Synthesis of Reduced Graphene Oxide-Wrapped Geobacter sulfurreducens as a Hybrid Electrocatalyst for Efficient Oxygen Evolution Reaction

“…The molecular mechanism of electron transfer to GO by EET-capable bacteria was only reported by few studies, where electron transfer to GO was mediated either directly by outer membrane cytochromes as in Shewanella oneidensis MR-1 18,19 or indirectly by redox mediator (e.g., vitamin K 3 ) as in Bacillus subtilis 168. 20 The reduction of GO to rGO was also been reported using mixed-culture inoculum such as anaerobic sludge, 23 river water, 24 water channel sediment and paddy soil, 24 with the main objective to demonstrate the applicability of GO for the selective enrichment of EET-capable bacteria from the environment.…”

Scaling up Microbial Fuel Cells for Treating Swine Wastewater

“…In this study, an MFC with a relatively small capacity (1.5 L) was used for swine wastewater treatment and subsequently scaled up to 12 and 100 L. The aim was to assess the application of scaled-up microbial fuel cells (MFCs) with different capacities (i.e., 1.5 L, 12 L, and 100 L) for removing organic matter from swine wastewater. A complex containing microbially reduced graphene oxide (rGO) and GO-reducing bacteria (rGO complex) was used as the anode material [24,25] for enhanced electricity generation from artificial dialysis wastewater and municipal sewage wastewater [26,27]. The performance parameters i.e., electricity production, COD removal efficiency (COD RE), and Coulombic efficiency of the different MFCs were compared.…”