Electrolytic hydrogen production from acidified wastewater effluent

Clean hydrogen provides a pathway to a sustainable energy future. However, current commercial water electrolyzers rely on high purity water, which can add significant stress on local water supply and additional economic burdens. To lessen the reliance on freshwater in electrolytic hydrogen production, alternative water sources such as reclaimed water (RW) from wastewater treatment facilities could be used. However, little is known how various water impurities in such source water impact the system performance and longevity. In this study, we characterized such impacts in lab-scale water electrolysis systems, and the results revealed that RW impurities primarily affected the membrane through contamination by cations. By acidifying the RW feedstock, we successfully extended electrolyzer stability from 8 h to over 300 h at a current density of 150 mA cm^-2. Furthermore, this acidification step reduced cost by 46.9 % and energy intensity by 61.8 % via the elimination of multi-stage RW pre-treatment. This work highlights the practical feasibility of reclaimed water electrolysis, enabling wastewater facilities to contribute to the broader integration of clean energy transition.