Development of an electrochemical system to convert wastewater ammonia to nitrogen and hydrogen

Increasing numbers of municipal wastewater treatment plants are being required to remove the ammonium present in sewage, because ammonia discharged to receiving waters promotes harmful algal blooms. Current treatment technologies rely on biological processes involving oxidation of ammonium to nitrate (nitrification) followed by reduction of nitrate to nitrogen gas (denitrification). This circuitous process is necessary because microorganisms lack the enzymes to convert ammonium directly to nitrogen gas. Biological processes are also cumbersome to operate. This project would develop a pilot-scale electrochemical system to convert some of the ammonium (NH4+) to ammonia (NH3), which can be harvested as an energy supply, while simultaneously oxidizing another portion of the ammonium directly to nitrogen gas. This process would avoid the inefficient, circuitous pathway to nitrogen gas required by biological processes. The electrochemical system would be coupled with ion-exchange processes that extract and concentrate ammonium from wastewater into a brine solution, where the high salt concentration provides a free source of conductivity that contributes to a more efficient electrochemical process.