Anaerobic/aerobic conditions and biostimulation for enhanced chlorophenols degradation in biocathode microbial fuel cells

Abstract

Anaerobic/aerobic conditions affected bacterial community composition and the subsequent chlorophenols (CPs) degradation in biocathode microbial fuel cells (MFCs). Bacterial communities acclimated with either 4-chlorophenol (4-CP) or 2,4-dichlorophenol (2,4-DCP) under anaerobiosis can degrade the respective substrates more efficiently than the facultative aerobic bacterial communities. The anaerobic bacterial communities well developed with 2,4-DCP were then adapted to 2,4,6-trichlorophenol (2,4,6-TCP) and successfully stimulated for enhanced 2,4,6-TCP degradation and power generation. A 2,4,6-TCP degradation rate of 0.10 mol/m(3)/d and a maximum power density of 2.6 W/m(3) (11.7 A/m(3)) were achieved, 138 and 13 % improvements, respectively compared to the controls with no stimulation. Bacterial communities developed with the specific CPs under anaerobic/aerobic conditions as well as the stimulated biofilm shared some dominant genera and also exhibited great differences. These results provide the most convincing evidence to date that anaerobic/aerobic conditions affected CPs degradation with power generation from the biocathode systems, and using deliberate substrates can stimulate the microbial consortia and be potentially feasible for the selection of an appropriate microbial community for the target substrate (e.g. 2,4,6-TCP) degradation in the biocathode MFCs.

Microbial electrolysis cells with biocathodes and driven by microbial fuel cells for simultaneous enhanced Co(II) and Cu(II) removal

“…5.0-7.0) is appreciably required to achieve a complete Cu (II) reduction on the cathodes of MFCs and thus avoids the adverse effects of Cu(II) and more acidic pHs on the electrotrophic activities in the connected MECs. In addition and in terms of product purity, the formation of pure copper on the cathodes of MFCs is heavily dependent on an anaerobic environment [2,31,32] whereas cobalt deposited on the biocathodes of MECs may have somewhat been chelating with the cellular surface and thus heavily depends on the characteristics of specific bacteria [3]. Relationship between the bacterial community and the specific mechanism cannot be concluded based on the species level results reported here.…”

Bioinspired Nanosucker Array for Enhancing Bioelectricity Generation in Microbial Fuel Cells

“…After 36 h, the liquid level in the capillary was observed to have risen by Δ h ≈ 1.2 cm, demonstrating the depletion of the O 2 in the capillary by the anaerobic sludge. [ 48 ] Contrastingly, there was no change in the liquid level for the control system without anaerobic sludge added in. Hence, despite the difference in scale, the above experiment provides an evidence for the high probability of the formation of vacuum condition in the PPy nano-SA-CT anode.…”

“…The cell membrane is permeable to gaseous oxygen stored in the space of nanosucker via free diffusion to proceed with facultative respiration in living bacteria. [ 48 ] Assuming that the oxygen partial pressure is 21% (0.21 × 10 5 Pa ≈ 266.8 mg L −1 ), diffusion coeffi cient ( D S ) for oxygen diffusing into microbial cells of ≈5.0 × 10 −9 m 2 s −1 , [ 49,50 ] the cell membrane thickness of 7.5 × 10 −9 m, [ 50 ] and contact area between a single nanosucker and cells of 7.85 × 10 −15 m 2 , the relationship between oxygen consumption and time in the inner space of nanosucker can be obtained from the calculation according to the Fick's law by taking into account of the dependence of pressure on time (Supporting Information). The results shown in Figure S7 (Supporting Information) account for oxygen diffusion from nanospace into bacterial cells driven by transmembrane pressure difference before the achievement of equilibrium.…”

Comparison of Co(II) reduction on three different cathodes of microbial electrolysis cells driven by Cu(II)-reduced microbial fuel cells under various cathode volume conditions

“…Cu(0) and Co(0) crystals can be also attributable to the cathodic strict anaerobic environment. Under an aerobic/facultative environment, dissolved oxygen can compete with species of Cu(II) and phenols for cathodic electrons, resulting in the formation of partial reduction products [3][4][5][6][7]28].…”