Science of Water : Concepts and Applications

348 The Science of Water: Concepts and Applications
Then we can calculate days’ supply in inventory:
Or
Example 10.42
total chemical in inventory, lb
Days’ supply in inventory
average
use, lbday total chemical in inventory, gal
Days’ supply in inventory
average use, galday Problem:
The chemical used for each day during a week is given below. Based on these data, what was the average
lb/day chemical use during the week?
Solution:
Example 10.43
Monday—88 lb/day Friday—96 lb/day
Tuesday—93 lb/day Saturday—92 lb/day
Wednesday—91 lb/day Sunday—86 lb/day
Thursday—88 lb/day
Average use, lbday total chemical used, lb
number of days
634 lb
7days
90.6 lbdays average use
Problem:
The average chemical use at a plant is 77 lb/day. If the chemical inventory is 2800 lb, how many days’
supply is this?
Solution:
PADDLE FLOCCULATOR CALCULATIONS
total chemical in inventory, lb
Days’ supply in inventory
average
use, lbday 2800 lb in inventory
77 lbday average use
36.4 days’ supply in inventory
(10.40)
(10.41)
The gentle mixing required for fl occulation is accomplished by a variety of devices. Probably
the most common device in use is the basin equipped with mechanically driven paddles. Paddle
fl occulators have individual compartments for each set of paddles. The useful power input imparted
by a paddle to the water depends on the drag force and the relative velocity of the water with respect
to the paddle (Droste, 1997).