Nature-based wastewater treatment technologies: A comprehensive review of constructed wetlands and vermifiltration

Water scarcity and inefficient wastewater management are critical global challenges. Nature-based solutions (NBS) such as Constructed Wetlands (CWs) and Vermifiltration (VF) have emerged as sustainable, decentralized approaches for wastewater treatment. This systematic review (PRISMA-guided) synthesizes recent evidence on CW and VF performance across multiple wastewater types (domestic, greywater, hospital, dairy, agricultural, and textile). Findings reveal that CWs consistently outperform in nutrient (TP, NH4+-N) and chemical pollutant removal, while VFs excel in TSS removal, rapid stabilization, and pathogen reduction. Importantly, this review highlights knowledge gaps in large-scale implementation and head-to-head trials. The innovative contribution of this work lies in proposing an integrated hybrid CW-VF framework, wherein VF units provide initial solid and organic load reduction, followed by CWs for nutrient polishing and advanced contaminant removal. This hybrid pathway can optimize land use, enhance efficiency, and improve resilience under varying wastewater profiles. Positioned within the global push for SDG 6 (Clean Water & Sanitation), this review provides both a synthesis of current research and a forward-looking strategy for advancing decentralized, eco-friendly wastewater management.