My sewage based microbial fuel cell design is advancing well, the sewage treats itself but net energy production is marginal. I am storing data and ideas that may be useful in improving the design. Krebs cycle occurs two times for each glucose molecule from glycolysis, since it occurs for each of the two molecules of acetyl coenzyme A formed by the oxidation of the two molecules of pyruvic acid. For each turn of the Krebs cycle, one molecule of ATP, three molecules of NADH, and one molecule of FADH2 (a coenzyme similar to NADH) are formed. Therefore, for one glucose molecule, the Krebs cycle results in the formation of two molecules of ATP, six of NADH, and two of FADH2. The NADH and FADH2 then undergo the electron transport chain, resulting in the production of more ATP.
The electron transport chain is the final stage of aerobic respiration. It utilizes the molecules of NADH and FADH2 formed during glycolysis and the Krebs cycle to produce great amounts of ATP. During glycolysis and the Krebs cycle, the NAD+ and FAD coenzymes were passed high energy electrons. The purpose of the electron transport chain is to pass those electrons to other carrier molecules which hold the electrons at slightly lower energy levels. As the electrons are passed from high to low energy levels, energy is released. After many steps, the electrons are finally accepted by oxygen at the lowest energy level, producing water.
Angenent and He have devised a microbial fuel cell which he calls an upflow microbial fuel cell (UMFC) that is fed continually and, unlike most microbial fuel cells, works with chambers atop each other rather than beside each other. "The upflow microbial fuel cell is a promising wastewater treatment process and has, as a lab-scale unit, generated electricity and purified artificial wastewater simultaneously for more than five months." Angenent uses a carbon-based foam with a large pore size on which biofilm grows, allowing him to connect two electrodes in the anode and cathode chambers with a conductive wire. The bacteria on the anode electrode acts as the catalyst instead of platinum. The electrons are supplied by the Krebs cycle summarized above.