Hybrid Advanced Oxidation Processes and Biofiltration for Sustainable Wastewater Treatment in Southwestern Algeria: Mechanisms, Performance, Modeling, and Future Perspectives

Freshwater scarcity in arid and semi-arid regions, coupled with increased population density, leads to greater demand and pressure on aquatic ecosystems and limited groundwater resources. This study, conducted using the PRISMA 2020 methodology, aimed to evaluate the effectiveness and sustainability of hybrid technologies that combine advanced oxidation processes (AOPs) with biological filtration in the treatment of urban and industrial wastewater. A systematic review was conducted between 2015 and 2026 using six main databases (Scopus, Web of Science, ScienceDirect, SpringerLink, PubMed, and Google Scholar). A total of 1248 studies were identified, of which 78 met the eligibility criteria and provided sufficient quantitative data for comparative synthesis. The results showed that hybrid systems, such as ozone biofiltration, Fenton-Membrane Bioreactor (MBR), and photocatalytic biofilm, have higher removal efficiencies for COD (>95%), microorganisms (>90%), and pathogens (>99%), with minimal residual sludge. The environmental assessment also demonstrates the strong potential of these processes when integrated into arid regions such as southwestern Algeria, due to their contribution to conservation of biodiversity and sustainable reuse of treated wastewater. Through this study, our objective is to highlight the role of integrated approaches in circular water management, as well as the urgent need to standardize protocols to assess the magnitude of long-term environmental impacts.