Advances in vermifiltration: A comprehensive review of recent developments and applications

Vermifiltration is an emerging, nature-based technology that relies on synergistic interactions between earthworms and microbes to remove organic matter, nutrients, and contaminants from wastewater. This review synthesizes recent advances from 2018 to 2024, highlighting innovations in system design, process optimization, and hybrid integrations that enhance its performance and applicability. Across various wastewater categories, including municipal, industrial, and agricultural effluents, vermifilters demonstrate high treatment efficacy. A meta-analysis of 14 studies reveals median removal efficiencies of 89.8 % for biochemical oxygen demand (BOD) and 81 % for chemical oxygen demand (COD), with typical removal ranging from 70 to 95 % and 65–90 %, respectively, and over 99 % for fecal coliforms. This review critically evaluates key operational parameters such as hydraulic loading rates, earthworm stocking densities, and filter media composition to discern performance trends. Furthermore, innovations like the integration of biochar-enhanced media and hybrid configurations with constructed wetlands improve system resilience and pollutant removal. Key co-benefits include minimal sludge generation, recovery of nutrient-rich vermicast for soil application, and significant mitigation of greenhouse gases like methane (CH₄) and nitrous oxide (N₂O), alongside effective odor control. Despite these promising outcomes, challenges persist, including filter bed clogging, temperature sensitivity, and a lack of standardized protocols, which constrain scalability and regulatory acceptance. Future research should prioritize system automation, long-term field trials targeting emerging contaminants, and the development of clear policy frameworks. Overall, vermifiltration presents a reliable, low-energy, and climate-friendly approach to advancing sustainable, decentralized wastewater management.