(357aq) A Laboratory Scale Continuous Reactor for Electrochemical Phosphate Recovery from Wastewater

Teaching Interests: Electrochemistry, Heat and Mass Transfer

Optimal food-energy-water resource management involves the efficient recovery and re-use of nutrients. In contrast, phosphate sources are limited and phosphate-rich fertilizers impact food security, leading to the need for energy-efficient technologies that utilize nutrient capture and reprocessing, like the production of electrochemical struvite (MgNH₄PO₄.6H₂O). An electrochemical up-flow reactor filled with pure magnesium shots was used to achieve electrochemical struvite precipitation. Pure Mg shots are cheaper and hence used as packing materials in the continuous reactor to offset the cost of raw materials. The electrochemical precipitation column was tested in a 10 mM synthetic solution of ammonium dihydrogen phosphate (NH₄H₂PO₄) with a sulfate background at different flow rates (2-5 LPM) and current (20-100 mA). As a next step, we investigated the practical application of the reactor, where we determined whether struvite precipitation was possible from municipal wastewater (PWW) source. The up-flow system achieved >90% and 70% phosphate removal efficiencies with simulated and real wastewater, respectively. Finally, efforts were made to quantify hydrogen evolved via the hydrogen evolution reaction (HER) mechanism at the electrodes during the precipitation process. Our initial results using a first-of-its-kind Mg shot up-flow reactor could further research on sustainable phosphorus recovery from wastewaters by using green technologies that contribute to energy and environmental sustainability.