CIVE 450 Problems Page 3, Spring 2014

13. Presedimentation reduces turbidity of a raw river water from 1400 mg/L suspended solids to 250 mg/L. How many kilograms of dry solids are removed per 3800 m*. If the settled sludge has a concentration of 10% solids and the specific gravity of 1.04, calculate the sludge volume produced per 3800 m° of river water processed. id the mixing intensity as measured by the root mean square velocity gradient water at 10 °C that will produce 5 kw mixer operating at 75% efficiency in a with a volume of 12 m°. water treatment plant designed to process 45,000 m°/d at a water e of 10 °C has a four-compartment flocculation tank with a total length h of 10 m, and water depth of 5.0 m. The paddle flocculator in each shambers between baffles has 4 blades, each 30 cm wide and 9.5 m center line of the paddles at a radius of 1.8 m. Assume the velocity % of the paddle velocity and the drag coefficient is 1.8. Ata 2.3 rpm, calculate the velocity gradient. in is divided into 16 channels by 15 around-the-end channels and at the slots are 0.18 and 0.6 m/sec., te is 0.34 m’/sec. Find (a) the total head loss neglecting wer dissipated ; (c) the mean velocity gradient at 15 14 I 5; @) the Gt value, if the detention time is 20 pal