(82e) Microbial Fuel Cell for Harnessing Sustainable Energy from Wastewaters Containing High Salt Concentrations or Produced Water

Authors: 
Ratnam, K. G., Joint Institute of Biological Sciences
Borole, A. P., Oak Ridge National Laboratory

Production of natural gas via fracking generates wastewater causing environmental pollution threatening the health of our drinking water supplies, rivers, streams and groundwater. The process generates massive amounts of polluted produced water. Produced water is conventionally treated through different physical, chemical, and biological methods. However, the conventional technologies cannot remove dissolved elements effectively. An upcoming technology, microbial fuel cells (MFC), can be a potential solution. It can generate bioenergy from the organics in the produced water. MFC application has documented a significant interest in the contemporary research area in harvesting energy in the form of bioelectricity. Anodic bacteria of the MFC play critical role in power generation and treatment efficiency of MFC. One of the approach to enhance the efficiency of MFC is enrichment of electroactive microbial biofilms capable of tolerating high salt concentrations. In current study, the effect of salt concentration in the anode chamber of a MFC fed with sodium acetate was tested with increasing concentration of NaCl from 10 g/L to 45 g/L. An MFC design with low electrode spacing, high specific electrode surface area with minimal dead volume, air-cathode and control of external resistance was used.  Maximum current density of 7 A/m2 was observed with the salt concentration of 35 g/L. The effect of salt concentration on current density and columbic efficiency will be discussed in light of the sensitive nature of the anodophilic bacteria to high salt concentrations.