1. How many million gallons are in a storage tank if 20 lbs of chlorine produced a dose of 4 ppm?

2. If a tank measured 40 ft in diameter and 30 ft tall, how many pounds of chlorine is needed to dose it at 9 mg/L?

3. A water pipe is 2 miles long and 18 inches diameter. How many pounds of chlorine would create a dose of 6 ppm? (5280 ft/mile)

4. If you pump 250 gpm and dose the effluent with 21 mg/L of chemical, how many pounds per day are you using?

5. If the plant influent was 50 ppm of BOD and the daily flow is 1.2 MGD, how many pounds per day are removed if the process removes 70% of the BOD?

Answers:

1. 4 ppm x 8.34 lbs/gal = 33.36 ppm/lb/gal
(20 lbs) / (33.36 ppm/lb/gal) = 0.60 mg

2. 0.785 x 40’ x 40’ x 30’ = 37,680 cuft x 7.48 gal/cuft = (281846.4 gal) / (1,000,000) = 0.282 MGD
0.282 MGD x 9 mg/L x 8.34 lb/gal = 21.2 lbs

3. (18 inches) / (12 inches/ft) = 1.5 ft
2 miles x 5280 ft/mile = 10560 ft
0.785 x 1.5’ x 1.5’ x 0560’ = 18651.6 cuft x 7.48 gal/cuft = (139513.97 gal) / (1,000,000) = 0.1395 MGD x 6 ppm x 8.34 lb/gal = 6.98 lbs

4. 250 gpm x 1440 min/day = (360000 gpd) / (1,000,000) = 0.36 MGD x 21 mg/L x 8.34 lb/gal = 63 lb/day

5. Convert 70 % to decimal = (70) / (100) = 0.70
1.2 MGD x 50 ppm x 8.34 lb/gal= 500.4 lbs
500.4 lbs x 0.70 = 350 lbs/day