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Évaluation de la qualité des cours d’eau de la ville de Taza utilisés dans l’irrigation des cultures maraîchères (Maroc).


M B Abbou
F Fadil
M El Haji

Abstract

Objective: Currently, the watershed of Oued Larbâa in Morocco is threatened by intensive pollution, given the enormous volume of discharges, without any pretreatment from the city of Taza. The total pollution released by the city of Taza is estimated to reach 30,354 m3 / d by 2015 (RADEETA, 2004). Agricultural use of the effluents from the river Larbâa is intense and is mainly vegetable crops. This use is associated with health risks necessities evaluation of the physico -chemical and microbiological characteristics of these waters.
Methodology and results: The results obtained in this study indicate that the physico- chemical and microbiological quality of the water used for irrigation of crops does not always meet the criteria for use set by the World Health Organization (WHO). Irrigation water stations downstream of discharges from the city of Taza polluted chemically and bacteriologically are characterized by low levels of dissolved oxygen, high levels of suspended solids (TSS), biological oxygen demand in 5 days (BOD5), chemical oxygen demand (COD), nitrate, orthophosphates and high rates exceed the limited value for the irrigation of heavy metals such as Iron and manganese as well as a significant presence of coliforms and faecal streptococci that exceed the limits set by WHO. The protection of these waters against various infections is necessary and imperative that these waters are still used in agriculture.
Conclusion and application of results: Contamination of water courses receiving waters of wastewater from the town of Taza, used in crop irrigation located in their vicinity, making them unsuitable for such use. In fact, reuse of these waters would be possible after biological treatment appears possible according to the values of the ratio of BOD5/COD obtained in this study, without ignoring the treatments for bacterial flora detected that presents a danger to the health of consumers of crops contaminated.

Keywords: Irrigation; Water Waste; Oued Larbâa; physico-chemical; bacteriological.


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eISSN: 1997-5902