Electrochemically Enhanced Modular Ecological Infiltration System for Removal of Neonicotinoid Pesticides and Conventional Pollutants

Neonicotinoid pesticides are persistent in aquatic environments, posing ecological risks. To address the limited removal efficiency of conventional soil infiltration systems, this study developed an electrochemically enhanced modular ecological infiltration system (MEIS) integrating iron–carbon micro-electrolysis to synergistically remove conventional pollutants (COD, NH3-N, TN, TP) and two typical neonicotinoids (NNs): imidacloprid (IMI) and imidaclothiz (IMIZ). Under optimized hydraulic loading (1.2 m3/(m2·d)), C/N ratio (3:1), and current density (0.016 mA/cm2), the system achieved high removal efficiencies for conventional pollutants (COD > 99%, NH3 N 99.8%, TN 81.7%, TP 85.4%). Notably, electrochemical enhancement significantly improved the removal of IMI and IMIZ to 78.1% and 69.1%, respectively, outperforming the non-electrified control. Adsorption kinetics indicated that the filler designed for autotrophic denitrification exhibited the highest adsorption capacity for both pesticides, with a chemisorption-dominated mechanism. Electrochemical enhancement likely enhanced the performance of MEIS by facilitating the release of anodic Fe2+ and the generation of reactive species, thereby achieving higher removal efficiencies for conventional pollutants and pesticides. This study presents an efficient and promising ecological technology for the treatment of pesticide-contaminated water, demonstrating strong initial performance and offering substantial potential for further optimization in terms of long-term stability.