Integrating adsorbents and electrochemistry to advance selective wastewater phosphate separations

Abstract

Excessive discharges of phosphorus from wastewater streams and agricultural soils have perturbed natural aquatic ecosystems by causing environmental issues like eutrophication. Reimagining liquid waste streams as potential feedstocks can recover valuable phosphate products and decrease reliance on phosphate rock mining for fertilizer production. This perspective underscores the significance of integrating adsorbents and electrochemistry as selective separation techniques, aiming to overcome the current limitations of phosphorus recovery techniques and enhance phosphorus recovery from waste. Compared to existing methods, efficient recovery methods are expected to exhibit reduced energy demands along with improved attributes such as enhanced selectivity, increased capacity, and greater reusability. Achieving these characteristics requires advances in mechanistic understanding of the molecular-level interactions driving the performance of adsorbents and electrochemical approaches. To guide material development, process performance, and mechanistic understanding, we discuss the potential of synchrotron-based techniques (e.g., X-ray imaging and spectroscopy) to assess adsorption mechanisms and processes that degrade the performance of phosphorus recovery approaches over time, including electrode degradation, precipitation, and fouling. Leveraging these molecular insights alongside life cycle analysis and technoeconomic assessments can directly guide process engineering decisions, improving wastewater-derived phosphorus product purity, uniformity, and overall value.