Question

1. A square rapid mixing basin, with a depth of water (i.e., basin's depth) equal to 1.25 times the width, is to be designed for a flow of 2 million gallons per day. G is 790 per second; detention time is 40 second; operating temperature is 10 °C. Determine the following: Basin dimensions Horsepower required (mixer is 100% efficient) • 2. A rapid mix tank, equipped with a mechanical mixer, will be used to mix the coagulant into water at 10 °C in 10 seconds with G of 800 per second for a flow of 10 million gallons per day. Find the following: • Power of the mixer motor assuming it operates at 70% efficiency

Answer 1

& Detention a time (DT) = 40 seconds flow rete @) = 2 maldoy ар . Squere basi I million 0= gallon = 3705.412 m lday 24x3600 seconds 2x 3705.4/2 0.0076 m3/see ( 24x3600) ) 9= volume of the squere basin ve 0-0076 x640) Jy = 3.504 m3 repid moune basin, kle know that for G= 790 je Dynemic virosity up wote @love i u = 1.307x103 pa. sec. ting (7² P 3:5044 1:367X163 [P= 2858.209 klah @) ar.my Depth of water (A) = 1.25x Width (B) Volume) = surface Aree (As) & Depth 1 v = (B2) xH 3504 (82)x(125)XB 1.25)XB width B = 1.41m | H= 1.28x141 H= 1-7625m | Spepth