Author(s): Thana Kamil Al-Shalchi; Najmiddin Al-Ani
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Keywords: River; Pollution; Mixing; Bend; Transverse mixing coefficient
Abstract: Al-Saidiya PN pumping station raw sewage discharges consists the major pollution source to Tigris river, between Al-Jadirriya and Al-Dora bridges, its importance comes from its location upstream to Al-Dora water treatment plant, and to the river hydraulic characteristics represented by the sharp U-shape bend that enhances the transversal mixing process, and hence facilitates the pollutants distribution, through the secondary currents and spiral flow. It was found that most pollutants concentrations at Al-Dora water treatment plant (WTP) range within the permissible level for Iraqi raw waters; with the exceptions of Coliform and Feacal Coliform that are highly above the limits; SO4 and BOD showed some high values. Oil & Grease high concentrations measured at Al-Saidiya pumping station showed that it should not be allowed to discharge directly to the river. Pollutants concentrations variation at Al-Dora WTP was found to be less than 5% of the mean over the river cross section, in what seems to be the completion of the transversal mixing. Variance distance relationship was used to evaluate the transverse mixing coefficient from three dimensional field measurements at Al-Saidiya outfall region; the calculated reach average transverse mixing coefficient, yε, was found to be 1. 02 m2/s. Normalization with channel average properties gave a value of 2. 98 which falls within the range of strongly curved channels (between 1 & 3).
Year: 2007