Open Discussion and Policy Priorities for 2019 and Beyond

In recent years, microbial fuel cells (MFCs) have attracted attention as a promising alternative to energy intensive and expensive methods of wastewater decontamination. However, the hypersaline wastewater (total salt content greater than 35g/L) common in the municipal waste of certain coastal cities, as well as the petrochemical, textile, leather, and fish industries has remained resistant to these efforts due to salt inhibition on bacterial cell activity. A wild-type strain of halotolerant bacteria isolated from the Great Salt Lake has yielded promising results for hypersaline wastewater treatment in MFCs under batch conditions. Remarkably, its ability to remove organic contaminants while generating a potential difference that is correlated to contaminant concentration allows for the monitoring of the decontamination process in real-time. For practical industrial purposes, the decontamination process would need to occur in a flow system, presenting a host of new factors with the potential to alter the electrocatalytic performance of the bacteria. To address these complications bench scale flow cells were developed, allowing for the determination of the effects of flow rate, flow cell configuration, methods of encapsulating bacteria, and operating conditions on signifiers of bioelectrochemical performance. Specifically, biofilm development, contaminant removal, and power output were investigated. Preliminary results show a magnitude decrease in power output from 15±5mW/m2 to 1.5±0.7mW/m2 and a 50% decrease in COD removal efficiency when flow is introduced. The results of the flow cell experiments are of paramount importance for the optimization and scaling up of an inexpensive and efficient system for the decontamination of hypersaline effluents.