Nesrine SAIDI ¹ Benjamin Erable ^2* ETCHEVERRY Luc ² ameur Cherif ¹ Habib Chouchane ^1*

• ¹ Higher Institute of Biotechnology of Sidi Thabet, University of Manouba, Sidi Thabet, Tunisia
• ² Département de Génie Chimique, École Nationale Supérieure des Ingénieurs en Arts Chimiques et Technologiques, Université de Toulouse, Toulouse, Occitanie, France

Thiabendazole (TBZ), a recalcitrant fungicide, is frequently applied in post-harvest fruit treatment, generates significant volumes of industrial wastewater that conventional treatment plants cannot handle. This explores a bioelectrochemical system (BES) for TBZ degradation using Tunisian hypersaline sediments (THS) as inoculum. Four sets of BES, together with biological controls were tested using THS subjected to different levels of TBZ biostimulation. Sediments underwent one, two, or three biostimulation phases with increasing TBZ concentrations (0,10, 100, and 300 mg kg⁻¹). Potentiostatic control was applied to BES, polarized at 0.1 V vs SCE, with a carbon felt working electrode (72 cm 2 L -1 ) and maintained at 25°C. While current production was very low, sediments biostimulated with 100 mg kg -1 kg TBZ produced the highest current density (3.2 mA m -2 ), a fivefold increase over untreated sediments (0.6 mA m -2 ). GC-FID analysis showed >99% TBZ degradation in all reactors. The TBZ half-elimination time from 27 days with biological treatments to 19 days inBES and further to 6 days following biostimulation. Bacterial analysis, analysis revealed a substantial microbial community shift after biostimulation, with a reduction in Bacillota (-64%) and an increase in Proteobacteria (+62%), dominated by Pseudomonas (45%), and Marinobacter (16%). These findings provide insight into the selective potential of biostimulation cycles to enhance microbial community composition and improve BES performance for TBZ wastewater treatment.