Crude water treatment - in circular setting tank with flow decelerating partitions for tangential influent

摘要

In a treatment for raw water, specially surface water or other effluents, water is mixed with a flocculant and introduced tangentially at the periphery into a tank. The circumferential velocity of the influent water is reduced by intermediate walls with perforations or deflector plates to a speed where upward secondary currents are suppressed. Clear water is discharged through a central standpipe. This system ensures optimum flow conditions at a minimum of engineering effort. Specifically, a cylindrical tank is fitted with a cylindrical partition which is assembled from perforated sheets to form an annular gap. This partition ends short of the tank bottom to leave space for raking arms (not shown). An axial standpipe in the centre is open at the top and passes through the bottom to discharge the clarified water.