Replacement of the biological treatment reactor with an MFC

It is important to keep in mind that an MFC has never been used at any scale larger than the bench-scale devices used in laboratory tests, and so at this time we have no specific data on system performance in the manner needed to specify unit processes and system 

There are three possible treatment process trains envisioned. First, it is expected that the MFC process could be incorporated into the process train in a more conventional system replacing the AS or TF systems. In this case, the MFC would be used in a manner similar to that of a TF in a TF/SC arrangement (Fig. 9.3A). The MFC reactor is a biofilm process, and thus the treatment should be more effective at removing sBOD than pBOD. Thus, a SC process would be needed to remove pBOD and achieve satisfactory treatment levels for domestic wastewater treatment. Recycle of the effluent from the MFC reactor to the influent line is not expected to be needed as in a TF process as contents of the reactor would likely be completely filled (versus a TF which is open to the atmosphere). The design of the SC and clarifier processes relies on the solids from the MFC acting in the same manner as the biofilm solids from a TF, which we will assume for our calculations. 

A second possibility for using the MFC in a process train is to have it as the pretreatment process for a membrane bioreactor (MBR) process (Fig. 9.3B). The MBR 

Configuring the electrodes in the MFC. The MFC electrodes currently thought to be the most suitable for scale up consist of high specific surface area graphite brush electrodes and tubular cathodes. These electrodes could be placed in sequence (/.e., anodes then cathodes) or randomly in the same tank (Fig 9.4). Groups of anodes and cathodes would form a single anode-cathode module, with many electrodes placed in a single tank or module. The brushes and tubes within the module would need to be in close proximity to each other to minimize the distance for proton transfer and thus 

The cost of the tube cathodes are higher than those of the brush anodes on a surface- 

---