Question

Please help with this environmental engineering problem

A new water treatment facility will be built to supply water to the town of Freemont. The town's population is currently 14,000 and the per capita water use is 100 gal per day. The new facility will be designed to account for increases in both per capita water use and population growth, and projections for water use will be determined for fifty years in the future. The population of the town of Freemont grows at an average rate of 2% per year. Based on historic trends for the town of Freemont, per capita water use increases at a rate of 0.1% each year. Question 3: Rapid and Slow Mix Design You have been assigned the job of designing rapid-mix and slow-mix tanks for the town of Freemont, using the groundwater aquifer as the water source. Design parameters for the rapid-mix tank: Detention time 2 mins No. of tanks: 2 velocity gradient (G) = 750 /s Impeller type: radial, with Np 3.6 Impeller diameters available 0.25, 0.5 and 1.0 m Tank length width B - Hwater/i3 Design parameters for the slow-mix tank: impeller: axial, Np = 0.40 Impeller diameters available: 1.0, 1.8 and 2.4 m Tapered G in 3 compartments: 90,60, 30 /s No. of tanks: 2 Detention time 30 min Tank length width B -Hwater/3 For both the rapid-mix and slow-mix tanks, determine: (i) Power input (assume 80% efficiency) (i) Tank dimensions Impeller diameter (iv) Rotational speed of the impeller H 1.85 x 105 Pa-s

Answer 1

ate 2oyears loo ates 50 yeans oo galfe OD 05 galda 9.xtd = 0173x2ー60 Volume d卜rapid-mix tank '

R= 1、51 m Huに 4.51 m Or Total towey input- 12529X2

es 3 2 ng D.75 60 use imbeller Dia05m. 1.57 32.

dl Volume vo3x 3oX m 2. LBH 155.2 m2

P2 1209.2 watt ー-/512watt

2. 2 1.54m 0.75 れ 2x 96. Ч

3912p) 2 SI 1B2.2mY) 015m Go Rapid thi지 T4nK