Microbial Responses to Electric Field in Model Systems and Wastewater Applications: A Comprehensive Review

The activated sludge process remains a cornerstone of biological wastewater treatment and relies on complex microbial consortia, including Bacteria, Archaea, and Fungi, for the degradation of organic pollutants and nutrient removal. The stability and efficiency of these microbial communities are influenced not only by wastewater composition but also by emerging technological interventions. The application of electric field (EF) has emerged as a promising and energy-efficient approach to improve treatment performance, modulate microbial behavior, and support bioresource recovery. Electric fields applied in wastewater treatment systems typically range from 5-20 A/m² or 30-500 V/m, while pulsed electric fields may reach intensities up to 3.0-3.8 × 10⁶ V/m (40-200 μs), and have been reported to influence microbial activity and treatment performance. This review provides a comprehensive synthesis of EF-microorganism interactions in model systems and wastewater treatment applications, adopting a hierarchical framework that links molecular mechanisms to community-level outcomes. We discuss how cell wall architecture and physiological state determine microbial susceptibility to electroporation and other EF-induced phenomena, with particular emphasis on the structural and functional responses of microbial cell envelopes, including peptidoglycan, lipopolysaccharides, and S-layers. At the molecular and cellular levels, EFs induce ion fluxes, redox imbalance, gene regulation, membrane perturbation, cytoskeletal reorganization, and stress adaptation. At the population and community levels, EF exposure modulates quorum sensing, extracellular polymeric substance production, microbial adhesion, and biofilm structure, ultimately driving shifts in microbial community composition and functional potential through electrokinetic phenomena. Together, these multiscale effects influence key wastewater treatment outcomes, including pollutant degradation, sludge settleability, and bioenergy recovery. By integrating mechanisms across biological scales, this review provides a conceptual roadmap for the rational application of EF-based technologies in sustainable wastewater treatment systems.