Efficient NH3-N recovery from municipal wastewaters via membrane hybrid systems: Nutrient-Energy-Water (NEW) nexus in circular economy

In the present-day scenario, conventional wastewater treatment technologies for effectively removing ammonia (NH3) from municipal/domestic wastewater sparked a major worldwide issue, which could be of fundamental matter to achieve a sustainable nitrogen cycle. The concerns over anthropogenic climate changes have stimulated universal scientific awareness to pursue scientific solutions in NH3 production to reduce its carbon footprint. The emerging Membrane Hybrid Systems (MHS), as a sustainable alternative to effectively remove/recover valuable resources, could be a major source of revenue that can play a vital role in the transition of conventional treatment plants towards advanced approaches to meet the needs of nutrient-energy-water (NEW) nexus in circular economy. This comprehensive review will cover major aspects affecting the recovery of NH3 from municipal/ domestic wastewater discharges. Development of membrane hybrid technologies toward techno-economic so-lutions, in terms of economic aspect, sustainability, and technical feasibility to bridge the gap between funda-mentals and practical. A novel Ranking Efficiency Index to evaluate the techno-economic features of the full-scale MHSs will be highlighted to aid researchers in achieving effectiveness from a broadly covered range of data perspectives. Beyond the separation performance of these systems, this review is for a wider community to delineate the future outlook for the next-generation wastewater treatment processes.