Integration of innovative advanced electrochemical processes into decentralized wastewater treatment

Decentralized wastewater treatment systems (DWATS) are increasingly recognized as sustainable solutions for off-grid sanitation and water reuse, yet conventional nature-based, anaerobic, and small-scale aerobic units often struggle to meet stringent effluent standards for pathogens, nutrients, and emerging contaminants. Advanced electrochemical processes—including electrocoagulation, electro-oxidation, bioelectrochemical systems, and hybrid electrochemical advanced oxidation—have recently been explored as enhancements to DWATS. This systematic review (2018–2025) analyzes approximately 120 studies selected from 2400 identified records per PRISMA criteria on integrating electrochemical technologies with decentralized treatment. The review highlights multiple innovations: (1) Electrified constructed wetlands and bioreactors that achieve higher removal of organics (often > 90% COD/BOD5) and micropollutants compared to conventional units; (2) Low-voltage electrochemical augmentation of anaerobic digesters boosting methane yields by 10–37% and enabling in-situ nutrient recovery (e.g., as struvite); (3) Coupling of electrochemical disinfection and advanced oxidation with aerobic/anaerobic units to attain pathogen-free effluents and degrade recalcitrant compounds, though at thecost of added energy demand. Integrated electrochemical-DWATS offer sustainability advantages, such as chemical-free operation via on-site generation of oxidants and compatibility with solar power, but also face challenges including electrode fouling, energy consumption, and scaling to community level. Quantitative comparisons indicate that bioelectrochemical systems can operate near energy-neutrality (even generating ~ 60 mW in field trials), whereas electrochemical advanced oxidation processes achieve more complete pollutant removal at higher energy costs (0.1–5 + kWh/m 3). Case studies demonstrate real-world feasibility. For instance, a 500 L/day solar-powered electro-Fenton system simultaneously removed > 85% of COD, ammonia, and phosphorus while disinfecting rural sewage. Overall, advanced electrochemical integrations can substantially enhance decentralized wastewater treatment performance and resilience. However, to realize their full potential, future efforts must address operational sustainability (minimizing power and maintenance needs) and validate long-term performance at scale. These innovations are central to a new generation of decentralized systems that safely reclaim water and resources, aligning with circular economy and climate goals.