Water post-treatment without expendables — proton exchange membrane based electrolysis system

Abstract

Abstract An electrochemical reactor which utilizes a proton exchange membrane (PEM) as the electrolyte is demonstrated for removal of organic and bacterial contaminants from reclaimed water. Electrochemical oxidation of organic compounds was carried out using the following procedures: (i) potentiostatic control of the anode below the potential for oxygen evolution at room temperature; (ii) galvanostatic control of the anode in the region of oxygen evolution at room temperature; and (iii) use of a regenerative electrochemical unit — a water electrolyzer/fuel cell operating in the electrolysis mode at 90°C. The rates of oxidation of the organic compounds and their current efficiencies were estimated. The oxidation of the organic carbon compounds was quite effective in the regenerative fuel cell (water electrolyzer/fuel cell) when operated in electrolyzer mode. This result thus reveals that the same electrochemical system can be used for three functions in space stations and space vehicles — hydrogen and oxygen production, electricity generation and oxidative removal of organic compounds and bacterial species from reclaimed water.