Évaluation de la pollution biologique de l’eau de l’Oued Boussellam : Autoépuration naturelle et essai de bioépuration

Abstract

This study focuses on analyzing the water quality of the Oued Boussellam through the evolution of physico-chemical parameters (pH, temperature, conductivity, BOD₅, total nitrogen, nitrogen forms) and microbiological parameters (total flora, coliforms, enterococci, coliphages, Pseudomonas, Clostridium) depending on sampling sites and periods. The results highlight a marked contrast between an upstream area (S1 to S3) that is heavily polluted due to domestic, agricultural, and industrial discharges, and a downstream area (S4) benefiting from an efficient natural self-purification process. The implementation of biological treatments using Bacillus subtilis D13 and Acinetobacter sp. MN6 enabled differential modulation of nitrogen transformation dynamics and pathogen reduction. D13 promotes partial denitrification and organic matter solubilization, while MN6 is characterized by its disinfection capacity and nitrogen storage in the form of biomolecules. Irrigation with these treated waters showed no phytotoxic effect on the germination of durum wheat, indicating their agronomic safety. The results support the relevance of a sequential bio-purification strategy to restore water quality and promote sustainable reuse.