Aptitude à l’irrigation des eaux usées traitées de la station d’épuration de Sidi Merouane Mila, Algérie.

Abstract

As part of a sustainable water resource management strategy and the reuse of treated wastewater in agriculture, this study aims to evaluate the physic-chemical quality of water from the Sidi Merouane WWTP (Mila Province, Algeria) for irrigation purposes. To this end, monthly analyses were carried out from January to May on parameters such as T°, pH, CE, TDS, DBO₅, DCO, N, NO₃⁻, PO₄³⁻, Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, SO₄²⁻, and HCO₃⁻. The results show neutral to slightly alkaline water (pH between 7,3 and 7,5) with moderate CE, reaching up to 1530 μS/cm, indicating acceptable salinity. TDS values averaged around 750 mg/L, close to the upper limits for sensitive crops. Peak concentrations were recorded in May, particularly for PO₄³⁻ (5,02 mg/L) and NO₃⁻ (6,2 mg/L), without exceeding critical thresholds. Water quality indices: SAR (2,87 to 3,29), Na% (48,5 to 52,3%), and KR < 1 , indicate that the water is conditionally suitable for irrigation, especially in well-drained soils. The Wilcox diagram classifies the water as moderately to highly saline, but with a low sodium hazard. The Riverside diagram (C3-S1) confirms this assessment. The Piper diagram analysis reveals a Cl⁻–SO₄²⁻ Ca²⁺–Mg²⁺ chemical faces, typical of a mixed influence between domestic effluents and local geology. In conclusion, this water can be used for irrigation under strict management, including drainage control, the selection of tolerant crops, and possibly mixing with higher-quality water.