Design criteria for pre-sedimentation basin treats Shatt Al-Arab River water

摘要

ABSTRACTThe design of Pre-sedimentation basins is based on design criteria including surface overflow rate and detention time. The previous studies differ in specifying the criteria values and, subsequently, it is difficult to choose the suitable ones according to raw water source characteristics. The aim of this study is to specify the design criteria values for pre-sedimentation basin treats the water of Shatt Al-Arab River. To satisfy this aim, experimental work was conducted including 51 plain sedimentation experiments and 37 particles size distribution analyses. The work results were used to determine the values of surface overflow rate and detention time in terms of actual and theoretical efficiencies of pre-sedimentation basin. The study results indicated that to use a pre-sedimentation basin in treating the water of Shatt Al-Arab River and the other rivers which have suspended solids with d50 values vary over the range (7.4-20.9) μm at efficiency exceeds 50%, the surface overflow rate must be less than 0.5 m/day and the detention time must be greater than 12.3 hr.