Electrochemical reactors represent an opportunity to use renewable electrons for phosphorus recovery from wastewater, while solving problems at the intersection of Food (nutrients) – Energy (electricity) – Water (wastewater) – Environment (biogeochemical cycles) systems. The recovery process is a reactive separation: orthophosphate speciation driven by the pH adjustments prior to precipitation from the solution. As such, this phosphorus recovery opportunity represents a challenge in both process intensification and multi-phase phenomena: the reactive recovery of a solid from water (at low cathodic potentials) or a solid and gas from water (at higher cathodic potentials). In essence, these reactor systems and their development are interesting from both an applied and a fundamental perspective.
In this presentation, electrochemical phosphorus recovery will be discussed through the lens of electrode stability and electrolyte composition and their respective impacts on reactor performance. First, the stability of the stainless-steel cathode within a wastewater simulant in comparison with a chloride-based electrolyte will be presented. This study provided insight into the effects of ions on electrode capacitance and corrosion as well as the protective nature of the wastewater electrolyte during phosphorus recovery. Second, the efficacy of phosphate recovery based on initial and evolving electrolyte composition during reactor operations will be described. This study provided insight into how the cation concentration may play a more crucial role than pH in phosphorus recovery.
