Probing the mechanism of simultaneous bioenergy production and biodegradation process of Congo red in microbial fuel cells

Abstract

BACKGROUND: Many approaches have been employed to increase the understanding and consequently the performance of microbial fuel cells to obtain simultaneous power production and biodegradation. This study uses recombinant Escherichia coli K-12 with MtrA, MtrC and MtrCAB inserts previously prepared using synthetic biology to evaluate the involvement of each of these genes in bioenergy production and biodegradation of Congo red using a double chamber microbial fuel cell. RESULTS:MtrC was the key gene required for energy production corresponding to an average voltage of 360 mV (external resistance 1 k ) and power density of 59 mW m -2 , while E. coli with MtrCAB insert showed the highest decolourisation which reached 80% in 36 h under microbial fuel cell conditions. Coulombic efficiency was 1.2% for E. coli with MtrCAB compared with 2.5% and 2.3% for MtrC and MtrA inserts, respectively. Riboflavin seems to be involved in the electron transferring, its concentration was highest for E. coli with MtrA insert despite its poor performance for both bioenergy production and dye degradation.CONCLUSION: This study suggests that electrons are mutually exclusive between electricity production, dye degradation and other cellular activities. This study helps to improve our understanding of the dual bioenergy/decolourisation process taking place in MFCs in order to maximize the outcome. Electrochemical measurementsVoltage output data were collected using a Picolog ADC-24 (PicoTechnology, UK) online data logging system, Cambridgeshire. Polarisation tests were done by connecting different values of external resistance once voltage had stabilized. Coulombic efficiency (CE) was calculated according to Fernando et al. 14 COD testsThe chemical oxygen demand removal was determined using the closed reflux titrimetric method as described by Westwood. 16 COD was calculated as follows:

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

“…Comparison of performance between C/N = 4 and C/N = 2 at 1000 Ω The unique advantage and limitation of Cupriavidus sp. S1 are effective nitrogen removal at high C/N ratios (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28) and the substantial restriction of denitrification at low C/N ratios (≤ 4), respectively. Therefore, the low C/N ratio in the cathode chamber at first was controlled at two values (4 and 2) at the R ext of 1000 Ω. Nitrogen in the synthetic wastewater was in the form of NO − 3 -N at the beginning of each cycle.…”

“…Recently, studies have increasingly paid close attention to the use of microbial fuel cell (MFC) to enhance nitrogen removal performance in wastewater treatment . MFC technology is a significantly prospective and completely different approach which has been shown to be effective in water pollution and energy shortage in contaminated water . Additionally, organic matter of anode chamber in MFC is a potential carbon source for nitrogen in the cathode chamber, indicating that it can facilitate denitrification of low C/N wastewater with characteristics such as no external carbon addition, rapid degradation of pollutant and part energy recovery .…”

“…19,20 MFC technology is a significantly prospective and completely different approach which has been shown to be effective in water pollution and energy shortage in contaminated water. 21 Additionally, organic matter of anode chamber in MFC is a potential carbon source for nitrogen in the cathode chamber, indicating that it can facilitate denitrification of low C/N wastewater with characteristics such as no external carbon addition, rapid degradation of pollutant and part energy recovery. 19 A few studies have detected that TN removal of low C/N wastewater in the cathode chamber of the MFC was more energy-saving and more economical than those using traditional methods.…”

In focus: microbial fuel cells, some considerations

“…This ‘In‐focus’ section of the Journal of Chemical Technology and Biotechnology (JCTB) covers a total of six manuscripts (two review papers and four original research articles) in microbial fuel cells reporting recent developments in MFC technology.…”

“…The review concludes that BES is promising for both in situ and ex situ environmental remediation applications in a sustainable manner. Gomaa et al . address the mechanism of concomitant degradation of the dye Congo red and bioelectricity generation using a recombinant strain of E. coli .…”