Hazardous landfill leachate: Integrated treatment strategies, regulatory frameworks, and circular economy perspectives

Landfill leachate (LL) is a complex and hazardous effluent that poses significant risks to ecosystem integrity and public health. The current review provides a critical evaluation of conventional and advanced LL treatment technologies, with an in-depth analysis of the performance and hybrid system combinations. We contend that integrated treatment systems, such as membrane bioreactors (MBRs) combined with improved oxidation processes, are essential for managing the variable and recalcitrant nature of LL. By aligning treatment strategies with circular economy principles, we highlight the potential for simultaneous pollutant removal and resource recovery (water, nutrients, energy). A techno-economic and life-cycle assessment reveals that while advanced systems such as MBRs and reverse osmosis (RO) achieve high effluent quality, their sustainability is often undermined by substantial energy demands and the generation of secondary waste streams. In contrast, hybrid systems that employ biological processes for bulk removal, followed by advanced polishing steps, offer a more balanced approach to cost-effective, environmentally sound management. We conclude that future research should prioritize the development of low-energy hybrid processes, integrated with real-time ecotoxicological monitoring, to achieve zero-liquid discharge and advance sustainable LL management that effectively mitigates environmental and human health risks.