Simultaneous microbial electrochemical degradation of methyl orange and bioelectricity generation using coculture as anode inoculum in a microbial fuel cell.

Methyl Orange, an azo dye, is a widely used colouring agent in the textile industry. The study aimed to investigate the efficiency of bioremediating bacteria in degrading methyl orange. Escherichia coli (E. coli), a Methyl Orange-degrading bacterium, was isolated from cow dung and its biochemical properties were analysed using 16S rRNA sequencing, and MALDI-TOF MS. A pre-cultured strain of Pseudomonas aeruginosa was co-cultured with E. coli in 1:1 ration in a microbial fuel cell (MFC) for simultaneous electricity production and methyl orange degradation. The degradation was combined with biological wastewater treatment at varying Methyl Orange concentrations, and the electrochemical characteristics were analysed through polarisation study, cyclic voltammetry, and electrochemical impedance spectroscopy. The impact of parameters such as anolyte pH, dye concentration, incubation time, and substrate concentrations were also studied. This study confirmed E. coli as an effective methyl orange degrading bacteria with a maximum % degradation efficiency of 98% after 48 h incubation at pH 7.0. The co-culture of isolated microorganisms at 250 mg/L of methyl orange concentration showed a maximum power density 6.5 W/m3. Further, anode modification with Fe2O3 nanoparticles on the anode surface enhanced power production to 11.2 W/m3, an increase of 4.7 W/m3.

Development and life cycle assessment of an auto circulating bio-electrochemical reactor for energy positive continuous wastewater treatment.

Bioelectrochemical systems like microbial fuel cells (MFCs) are quaint systems known to metamorphose the chemical energy of organic matter into electrical energy using catalytic activity of microorganisms. A novel continuous Auto Circulating Bio-Electrochemical Reactor (AutoCirBER) was developed to fulfil the gap of 'simple, inexpensive and compact design' that can continuously treat larger amount of organic wastewater at shorter residence time and without consuming external energy for liquid mixing. AutoCirBER eliminated the need for external agitation for liquid-mixing and therefore, energy requirements. AutoCirBER was operated in continuous-mode and hydraulic retention time was optimized. The reactor underwent performance check-up viz. COD removal, net power output, columbic efficiency, sludge generation and an attributional life cycle assessment (LCA) was also conducted. AutoCirBER was sustainable to run in continuous-mode and showed more than 90.4% of COD removal, and 59.55 W.h net annual energy recovery. Experimental LCA of AutoCirBER also displays its environmental feasibility in longer run.