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Increasingly, circularity indicators for material, energy, and water systems guide circular economy design. While indicators for products made from recycled carbon-based materials are somewhat common, peer indicators for waste nitrogen-derived products are limited. It is important, however, to develop such indicators to guide emerging technologies that transform waste nitrogen into products. In this study, we summarize the nitrogen circularity indicator literature, emphasizing the agricultural and wastewater sectors. Next, we use the Material Circularity Indicator (MCI) developed by the Ellen MacArthur Foundation, to quantify the circularity of products made from waste nitrogen in swine manure. We considered four test cases using different technologies to recover nitrogen from the manure. Our analysis indicates that technologies that seem to increase circularity on the surface may not yield a substantial increase in MCI results. Finally, we discuss the strengths and weaknesses of using the MCI for product-level analysis and further developments. 

The nitrogen cycle needed for scaled agriculture relies on energy- and carbon-intensive processes and generates nitrate-containing wastewater. Here we focus on an alternative approach—the electrified co-electrolysis of nitrate and CO2 to synthesize urea. When this is applied to industrial wastewater or agricultural runoff, the approach has the potential to enable low-carbon-intensity urea production while simultaneously providing wastewater denitrification. We report a strategy that increases selectivity to urea using a hybrid catalyst: two classes of site independently stabilize the key intermediates needed in urea formation, *CO2NO2 and *COOHNH2, via a relay catalysis mechanism. A Faradaic efficiency of 75% at wastewater-level nitrate concentrations (1,000 ppm NO3− [N]) is achieved on Zn/Cu catalysts. The resultant catalysts show a urea production rate of 16 µmol h−1 cm−2. Life-cycle assessment indicates greenhouse gas emissions of 0.28 kg CO2e per kg urea for the electrochemical route, compared to 1.8 kg CO2e kg−1 for the present-day route.