Enhanced low C/N nitrogen removal in an innovative microbial fuel cell (MFC) with electroconductivity aerated membrane (EAM) as biocathode

Abstract

A novel microbial fuel cell (MFC) was developed to enhance simultaneous nitrification and denitrification (SND) by employing electrons from the anode. The cathode chamber of the reactor consisted of a membrane aerated biofilm reactor (MABR) which was made of an electroconductivity aerated membrane. The maximum power density of 4.20 ± 0.12 W m-3 was obtained at a current density of 4.10 ± 0.11 A m-2 (external resistance = 10). Compared with an open-circuit system, the removal rates of NH 4 +-N and TN were improved by 9.48 ± 0.33% and 19.80 ± 0.84%, respectively, which could be ascribed to the electrochemical denitrification. The anode (chemical oxygen demand, COD) and cathode (NO 3-) chambers reached the maximum coulombic efficiencies (CEs) of 40.67 ± 1.05% and 42.84 ± 1.14%, respectively. It suggested that the electroconductivity MABR has some advantages in controlling aeration intensity, thus improving SND and CEs. Overall, EAM-MFC could successfully generate electricity from wastewater whilst showing high capacity for removing nitrogen at a low COD/N ratio of 2.8 ± 0.07 g COD g-1 N.

Enhanced nitrogen removal of low C/N wastewater using a novel microbial fuel cell (MFC) with Cupriavidus sp. S1 as a biocathode catalyst (BCS1)

“…S1 domesticated in the BCS1‐MFC system could accept electrons from the external circuit to reduced nitrate, and at the low resistance, the increase in current effectively transferred more electrons from the anode to the cathode electrode, which promoted reduction of ‐N in the cathode chamber. The conclusion was identical to the findings from other studies …”

“…The result was consistent with the observation from the studies by Tian et al . 27 and Wu et al . During the experimental process, the suspended biofilm formed more rapidly in the anode chamber at 100 Ω than at 200 Ω and 500 Ω, indicating that low load promoted the rapid formation of an electroactive biofilm on the anode surface.…”

“…The average TN removal rate was obtained 0.0461 kg N (m 3 d) −1 (100 Ω)， which was slightly higher than that of the previous study (0.040 kg N (m 3 d) −1 ) and lower than that accomplished by Wu et al . (0.128 kg N (m 3 d) −1 ) . This effect may be easily understandable because the cathode dynamics was decreased with the reduction of electron acceptors concentration without continuous supplement.…”

“…reported nitrogen removal of low C/N wastewater in a MFC with electroconductivity aerated membrane (EAM) as biocathode. TN removal efficiency and rate were about 80.82% and 0.128 kg TN (m 3 d) −1 at the R ext of 5 Ω, respectively . In these previous studies, nitrate was reduced in the cathode by bioelectrochemical and heterotrophic denitrification with mixed bacteria collected from activated sludge in wastewater treatment plants.…”

Resource recovery by osmotic bioelectrochemical systems towards sustainable wastewater treatment

“…The high pH of the catholyte due to reduction reactions converts ammonium ions to ammonia, which can be driven off the catholyte with mechanical mixing or aeration for recovery. Various BES including microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) have been studied to achieve ammonia recovery (CordRuwisch et al 2011, Wu et al 2017). Because higher current generation would greatly enhance ammonium transport towards recovery (Kelly and He 2014), MECs with external power exhibit a better performance for ammonia recovery than MFCs (Haddadi et al 2013).…”