Assessment of industrial wastewater quality from classified facilities in the Setif industrial zone, Algeria.

This study aims to assess the evolution of the physico-chemical and biological parameters of industrial wastewater in the industrial zone of Setif city (Algeria) during 2021-2023; in addition to evaluating the seasonal variability of these effluents, this work also examines the resulting repercussions on the water quality of the Oued Bouaroua, which flows through the industrial zone. The analysis of these parameters reveals strong seasonal variability. Indeed, the summer and autumn periods are the most critical conditions characterized by high temperatures reaching up to 20.8 °C, a significant decrease in dissolved oxygen (0.13 mg/l), and alarming levels of organic pollution BOD5, = 490 mg/l, COD = 1740.77 mg/l, SS = 660.51 mg/l, and turbidity = 658 mg/l. The pH measurements show that the water is highly acidic where the mean of this parameter does not exceed 2.5 (highly acidic hydroecosystem). Furthermore, the highest value of electrical conductivity recorded is 16,980 µS/cm. The sulfate levels are 1831.26 mg/l during winter 2021. Nutrient concentrations indicate remarkable spatio-temporal variations, where the highest nitrate concentration is recorded during spring 2021 with 35.57 mg/l. Also, a very significant nitrite concentration reaching a value of 3.95 mg/l was noticed. Irregular iron levels reflect episodic local contamination, reaching over 300% above the Algerian limit. These findings call for enhanced summer effluent control through integrated water management, sustained monitoring, and effective industrial wastewater treatment to preserve water quality and ecosystem health.