Life cycle assessment of membrane electrochemical systems for ammonia nitrogen recovery from wastewater

This work presents a cradle-to-gate life cycle assessment of ammonia (NH₃) recovery, quantified as ammonium nitrogen (NH₄-N, as N), from wastewater using membrane electrochemical systems (MES). Five lab-scale configurations, including three single-membrane configurations (2V-1 N, 5V-1 N, and 10V-1 N) along with two multi-stack configurations (5V-11 N and 10V-20 N), were evaluated for environmental impact, energy intensity, and recovery performance per functional unit of 1 kg NH₄-N recovered. The different configurations presented in this work use a variation of energy and material inputs per functional unit to illustrate the trade-offs among the different scenarios and to explore a sustainable balance between recovery rate, energy intensity, and environmental performance. The multi-stack membrane configuration (10V-20 N) not only demonstrated technical feasibility, but also competitive environmental performance, with a lowest GWP of 1.756 CO₂-eq per kg NH₄-N, lowest energy requirement (0.3 kWh per kg NH₄-N), and a net eutrophication potential of -0.767 kg N-eq per kg NH₄-N. Additionally, this work presents a comparative analysis encompassing (1) conventional NH₃ synthetic production, (2) established nitrogen (N)-removal processes such as air stripping and nitrification-denitrification, and (3) NH₄-N recovery using the configurations developed in this study. The findings aim to provide a foundation for scaling these systems to pilot and eventually commercial applications, while guiding decision-makers to recognize the environmental and economic opportunity of N recovery and the typically overlooked trade-offs that conventional synthetic production requires, such as additional energy and cost required to remove nutrients from wastewater.