The Zero-Waste Paradigm: Sustainable Engineering for Water and Wastewater Treatment, Resource Recovery, and Circular Economies

In an era defined by intensifying water scarcity and accelerating resource depletion, conventional linear waste management models—predicated on "take, make, use, and dispose"—are no longer ecologically or economically viable. The modern research landscape is shifting toward Zero Waste Discharge (ZWD), a paradigm that demands the complete elimination of waste streams by transforming environmental residuals into high-value assets. Achieving true ZWD requires moving beyond mere pollutant mitigation; it necessitates a holistic technological framework that unifies Sustainable Engineering, Resource Recovery, and the Circular Economy. The baseline of any ZWD framework is the mitigation of secondary pollution. Rather than relying on energy-intensive processes or synthetic chemicals that generate hazardous sludge, contemporary sustainable engineering spearheads the development of low-carbon, energy-neutral technologies. By prioritizing bio-based materials—such as biochar and functionalized lignin—for advanced pollutant removal, modern systems ensure that the treatment process itself does not introduce new environmental liabilities.The modern water sector is hindered by a "linear legacy" where treatment plants act as energy-intensive sinks rather than resource factories. Traditional systems suffer from significant technical leakages, failing to intercept emerging contaminants like microplastics and PFAS. This inefficiency is compounded by resource dissipation—treating phosphorus and nitrogen as pollutants instead of agricultural assets—and high energy demands, with aeration alone consuming up to 80% of total power. Furthermore, residual sludge remains a costly liability, typically destined for landfills rather than being repurposed for materials or energy.The "Upcoming Future" addresses these challenges through digitalization and the circular nexus. AI-optimized adsorption now utilizes machine learning to predict breakthrough curves, ensuring bio-adsorbents are used with maximum precision. This is complemented by decentralized modular units that allow for localized, 100% water recycling, bypassing inefficient central infrastructure. These advancements converge on the goal of Zero Liquid Discharge (ZLD), a visionary paradigm where every drop of water is recycled and every solid residual is converted into secondary raw materials like bioplastics. By integrating advanced engineering with smart technology, the industry is transitioning from simple waste mitigation to a closed-loop system that eliminates the very concept of waste.We welcome Original Research, Review, Mini Review and Perspective articles on themes including, but not limited to:• Emerging waste-to-resource recovery technologies (Adsorption, Filtration, Advanced Oxidation Processes, Catalysis etc.)• Innovations in process engineering and reactor design for RtR applications• System integration and optimization within municipal and industrial frameworks• Life-cycle assessment (LCA) and techno-economic analysis (TEA) of ZWD methods• Environmental impact mitigation in RtR systems• Policy, regulatory, and social considerations in sustainable ZWD deployment• Post-saturation management of spent adsorbents (e.g. biochar and other solid-phase materials): addressing the phase-transfer problem whereby pollutants captured from the liquid phase are retained in the solid phase, including safe disposal, regeneration, and valorisation strategies for pollutant-laden adsorbents Topic editors: Prabhat Kumar Patel, Deeptimayee Pal Source: https://www.frontiersin.org/research-topics/83111/the-zero-waste-paradigm-sustainable-engineering-for-water-and-wastewater-treatment-resource-recovery-and-circular-economies