Effects of pH variations on anodic marine consortia in a dual chamber microbial fuel cell

Abstract

The effect of anodic pH on Microbial fuel cells (MFCs) inoculated with marine consortia was investigated to characterize the microbial community adaptation to possible pH environmental changes and to define the pH extreme boundaries beyond which MFCs do not run properly. Tests were conducted in triplicate using different feeding pH values (pHfeed) ranging from 3 to 13. The MFCs inoculated with marine consortia had a strong self-regulation ability and actively counterbalanced small variations in pHfeed maintaining the pH inside the anodic chamber (pHanode) close to neutrality. As soon as the pHanode deviated from neutrality it affected MFCs' performances. Alkaline conditions with pHanode values between 8 and 10 corresponded to the formation of a denser biofilm together with the best performance in terms of maximum power density (Pmax). Conversely, when the pHanode reached values lower than 5.5 or higher than 10, a sharp drop in MFC performances, as well as a decrease of viable population, were observed. Interestingly, the system was able to survive these extreme conditions and restart working effectively when neutrality was reset. The obtained results underline the high adaptability and recovery ability of anodic marine consortia even in extreme conditions, suggesting the employment of this inoculum for MFC applications as biosensors for on-site seawater monitoring or as power supply units to be installed in remote area.

Electrospinning‐on‐Electrode Assembly for Air‐Cathodes in Microbial Fuel Cells

“…The electrolyte was constituted by 12 × 10 −3 m sodium acetate as carbon‐energy source and 5.8 × 10 −3 m of ammonium chloride dissolved into phosphate buffer saline solution (pH = 7.4, 140 × 10 −3 m of sodium chloride, 2.7 × 10 −3 m of potassium chloride and 10 × 10 −3 m of sodium phosphate buffer in distilled water) to maintain a value of pH close to 7. A seawater sediment sample was used as the inoculum source (from Liguria, Italy) . As described in our previous work, to induce the formation of biofilm on anode electrode, an external load of 560 Ω was applied between anode and cathode during the first part of experiment, known as stabilization phase .…”

Electricity generation in a microbial fuel cell using yogurt wastewater under alkaline conditions

“…It has been reported that alkaline conditions in anolyte can enhance electricity generation in the MFC. [6][7][8] The maximum power density in the MFC with pH 9.0 anolyte was 38.6% higher than that with pH 7.0 using acetate as substrate. 6 The coulombic efficiency (CE) increased from 43 AE 10% at neutral pH to 60 AE 5% at pH 9.5 in the MFC fed with acetate.…”

“…7 Previous studies also demonstrated that electricity could be produced in the MFC inoculated with marine consortia even with anolyte pH of 13 (7 mW m À2 ). 8 Many EABs can keep high activities under alkaline conditions. [10][11][12][13] The maximum power density in the MFC inoculated with Shewanella oneidensis MR-1 increased by $2.5 times when the analytic pH increased from 7.0 to 9.0 (102 vs. 40 mW m À2 ) using 5% LB medium and 95% M9 minimal medium.…”

Electrochemical analysis of microbial fuel cells based on enriched biofilm communities from freshwater sediment

“…Experiments were conducted in two-chamber fuel cells (chamber volume 58 mL), described in [24]. Briefly, a Cation Exchange Membrane (CEM, CMI-7000, Membranes International Inc., USA) was used to separate the two compartments; anode and cathode electrodes consisted of a carbon felt with an area of 38.5 cm 2 (Soft felt SIGRATHERM GFA5, SGL Carbon, Germany); electrical contacts to the electrodes were made using graphite rods; an Ag/AgCl reference electrode was inserted into the anodic chamber.…”