Effects of microbial species, organic loading and substrate degradation rate on the power generation capability of microbial fuel cells

Abstract

Four microbial fuel cells (MFCs) inoculated with different bacterial species were constructed. The species were Pseudomonas putida, Comamonas testosteroni, Corynebacterium gultamicum, and Arthrobacter polychromogenes. The MFCs were operated under identical continuous flow conditions. The factors affecting the capabilities of the MFCs for treating organic matter and generating power were evaluated and compared. The factors include microbial species type, organic loading, and substrate degradation rate. For all four MFCs, power output increased with the organic loading rate. Power density also increased with the substrate degradation rate. These findings implied that more organic matter was utilized for power generation at higher organic loading and substrate degradation rates. However, coulombic efficiency increased with decreased organic loading and substrate degradation rates. Apparently, all four MFCs had low efficiencies in generating power from organic matter. These low efficiencies are attributed to the long distance between the anode and the cathode, as well as to the small ratio of the proton exchange membrane surface area to the anode chamber surface area. These features may have caused most of the protons produced in the anode chamber to leave the chamber with the effluent, which led to the low power generation performance of the MFCs.

Using live algae at the anode of a microbial fuel cell to generate electricity

“…Mini-sized two-chambered MFC with an effective volume of 5 ml and flat square-shaped electrodes made with carbon paper (Toray, Japan) of surface area at 9.0 cm 2 (3.0×3.0 cm) Fig. 8 a (left) Power density (mW/m 2 ) versus current density (mA/m 2 ) and (right) voltage (mV) versus current density (mA/m 2 ) in model 1 MFC with algae grown at the anode (5.94×10 6 cells/ml) with the addition of Na 2 SO 3 (1 g/l) under the intensities of light of (1) 2500 (black square); (2) 3500 (black triangle); and (3) 6500 lx (black diamond), using equipment 1. b (left) Power density (mW/m 2 ) versus current density (mA/m 2 ) and (right) voltage (mV) versus current density (mA/m 2 ) in model 1 MFC with algae of cell densities of (1) 3.68×10 7 (black diamond); (2) 3.08× 10 7 (white square); (3) 1.39×10 7 (white triangle); and (4) 5.94×10 6 cells/ ml (black circle) at the anode of MFC at 3500 lx with the addition of Na 2 SO 3 (1 g/l), using equipment 1. c (left) Power density (mW/m 2 ) versus current density (mA/m 2 ) and (right) voltage (mV) versus current density (mA/m 2 ) with algal density at the anode of 5.94×10 6 cells/ml with light intensity of 3500 lx and sodium sulfite (1 g/l) using equipment 2 (5 ml mini MFC) in (1) model 1 algal MFC (algae at the anode and potassium ferricyanide at the cathode, black square) and (2) model 2 algal MFC (with an algal density of 5.94×10 6 cells/ml at the cathode with high-salt medium at 3500 lx, white triangle) energy conversion (Juang et al 2011). Instead, algae would produce organic compounds by photosynthesis and at the same time decompose them by metabolism to yield electrons.…”

“…According to the findings of previous studies, organic loading rate (Juang et al 2011), the type of material used (Chang et al 2014), surface modification in the electrode (Zhu et al 2011), and surface area of and the distance between electrodes (Sajana et al 2013) would highly determine the power output in the MFC. In the consideration of cost, the cheap and simple plain graphite/carbon electrodes in a two-chambered MFC were used in our present study.…”

“…MFC technology could employ miscellaneous materials as fuels including glucose (Li et al 2010a), alcohols (Kim et al 2007), and acetate (Liu et al 2005), even a few toxic and biorefractory organics such as nitrobenzene (Li et al 2010b) and phenol (Luo et al 2009). The power output would be promoted by increased organic loading rate (Juang et al 2011). However, electricity generation heavily relying on substrate input would make the system not cost-effective (Franks and Nevin 2010).…”

Novel Applications of Microbial Fuel Cells in Sensors and Biosensors

“…Regardless of the waste removal, operating at optimum OLR or sludge loading rate (SLR) is critical for an effective performance of MFCs, since both power density and current efficiency depend on the substrate conversion rate directly related to OLR [63,71,[94][95][96][97][98][99][100][101][102][103]. Thus, the energy generation is generally boosted by increasing the OLR up to a maximum, from which higher loading rates decrease the power output of the MFC.…”

Analysis of ethanol in fermentation samples by a robust nanocomposite-based microbial biosensor

“…Another direction of whole cell use is construction of biosensors to read biological O 2 demand value, presence of inhibitors, toxic compounds, utilisable organic matter and for generation of electric energy in the biofuel cells (Moon et al 2004;Lei et al 2006;Lovley 2006;Logan 2008;Tkac et al 2009;Su et al 2011;Juang et al 2011). There is still a main limitation for practical application of microbial biosensors such as a low sensitivity of oxidation of a particular analyte limiting their overall performance.…”