A microbial fuel cell (MFC) with an algae-assisted cathode is a low-cost and sustainable way to provide the oxygen for the oxygen reduction reaction. The anode was with anaerobic microorganism, a kind of photosynthetic bacteria (PSB-B). An algae bioreactor was connected to cathode microbial fuel cells to increase power generation by supplying more oxygen to cathode electrode. In this study, we used red, blue and white LED light as the light source, and the anode and cathode were under irradiation respectively. The result showed that white LED light was an effective factor for the anode, the cell voltage was built up from 34 mv to 60 mv, power density increased up to 2.5 mW/m2, the red and blue light had positive impact on the voltage. At cathode, the voltage was almost on steady stage conditions, and it was fluctuated around 35 mv by oxygen bubbles that were produced by algae. This relatively simple method increased the oxygen reduction rate at a low cost and could be applied to improve the performance of MFC.
Electricity generation with the bacteria as catalyst the MFC anode is a special, environmental way. It was a kind of bioelectrochemical system that can generate electricity by active bacteria [
MFC is composed of anode and cathode. At anode, electrons are liberated by the organic compounds oxidizing. These electrons move through to the cathode. At cathode, electrons combine with an electron acceptor. The chemical energy of substrates can be transformed into electrical energy by the metabolic activity of microorganisms. Recently, some researchers have found microbial technology for wastewater nutrients treatment using MFC providing a novel, efficient and cost-effective solution for increasing the concentration of oxygen at the cathode. The anode chamber was full of a medium containing a synthetic wastewater [
This research used a different signal acquisition system and special software of signal collection. It could show the potential changes during a short period and could help us to discover the little changes and convenient for analysis. The mul- timeter was not accurate for the tiny cell voltage observation, it could not be observed visually for the change in a short period.
MFC reactors comprised 11 mL anode chambers and 11 mL cathode chambers, separated by a proton exchange membrane (PEM). In this study, the anode and cathode were irradiated with different light sources severally. The anode was made of carbon cloth. Characteristics of the carbon cloth included thickness of 360 μm, the active area of each material was 14 cm2 (7 cm2 × 2) and area of 90 - 120 cm2/g, served as electrode material [
In the start-up of MFC reactor, anode was filled with bacterial culture suspension of PSB-B. PSB-B was cultured at 35˚C for 3 days. Culture medium: peptone 0.2%, yeast extract 0.2%, CH3COONa∙3H2O 0.2%, MgSO4∙7H2O 0.02%, NaCl 0.2%, NaHCO3 0.3%, K2HPO4 0.05%, CaCl2 0.005%, trace element solution 10 mL/L [
Before packing into the chambers, the carbon cloth electrodes were submer- ged in 1 N HCl for 24 h, washed with deionized water, then submerged in 1 N NaOH for 24h and finally washed several times in deionized water [
A glass bottle was used as an algae (Spirulina platensis, saved in College of Life Science Cytology Laboratory, Shanxi Normal University) bioreactor with a wor- king volume of 220 mL and 30 mL head space (BG11 medium), the algae was cultured at 25˚C for 15 days (0.8 g/L algae dry biomass).
In this study, the MFC reactor was continuously operated at a room temperature of 25˚C. The wavelength of red: 610 - 620 nm, blue: 465 - 485 nm, white light is a hybrid of light. Here, we used a signal acquisition device (NI USB-6008), it could acquire 1000 signals a second. The input resolution: 12, max sampling rate: 10 kS/s, working voltage: ±10 v. It was connected with the computer and it could record all data conveniently.
The anode MFC generated a voltage around 60 mV with suspension of PSB-B at the beginning, there was a potential sliding direction with no light. The FMC could generate electricity during the dark period, algae consume oxygen to oxi- dize the organic matter previously created to obtain energy. In this way, during the dark period, oxygen is consumed by the respiration of algae and reduction reactions which take place in the cathodic chamber [
In
In order to analyze the characteristics of the signal, we did a simple signal frequency chart, most of the voltages were distributed under 5 Hz. Therefore, the
could generate a steady cell voltage and it could be useful for the practical application. In this study, we could find out voltage fluctuation under the red light in
The microbial fuel cell is a device that converts the chemical energy of organism into electrical energy with the aid of biocatalytic reactions and carried out by microorganisms. The microbial fuel cell with an algae-assisted cathode has been
provided to voltage 200 mV and kept steady at 30 - 50 mV, 0.5 - 20 mW/m2. The light source had different effect on anode and cathode. Therefore, a PSB-assisted anode is efficient on generating electricity for MFC.
Rong, G. and Hu, Q.P. (2017) The Effect of Different Wa- velength of Light for Microbial Fuel Cell with an Anode of Rhodopseudomonas fae- calis (PSB-B). Open Access Library Journal, 4: e3389. https://doi.org/10.4236/oalib.1103389