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This practice test involves the usage of the chemical poundage /chemical dosage formula. In all likelihood, fifty percent of the math questions on any introductory-level water treatment facility operator exam will involve the calculation of chemical poundage and chemical dosages.
lbs. = MG x ppm x 8.34
MG = lbs. / ppm x 8.34
ppm = lbs. / MG x 8.34
1. How many gallons of water will 5000 pounds of ferric sulfate treat at a dosage of 40 ppm?
A. 25 MG
B. 15 MG
C. 30 MG
D. 35 MG
2. What is a water treatment plant's NaOH dosage if the plant uses 1000 pounds of NaOH to treat ten million gallons of water?
A. 8 mg/l
B. 10 mg/l
C. 12 mg/l
D. 15 mg/l
3. How many pounds of alum must be used to treat 20 million gallons of water with an alum dosage of 34 parts-per-million?
A. 2744 lbs.
B. 1360 lbs.
C. 8253 lbs.
D. 5671 lbs.
4. What is a water treatment plant's sodium polyphosphate dosage if the plant uses 125 pounds of sodium polyphosphate to treat ten million gallons of water?
A. 1.0 ppm
B. 1.5 ppm
C. 2.0 ppm
D. 2.5 ppm
5. How many pounds of coagulant-aid polymer must be used to treat sixteen million gallons of water to obtain a coagulant-aid polymer dosage of .75 mg/l?
A. 100 pounds
B. 200 pounds
C. 300 pounds
D. 400 pounds
6. How many gallons of water can be treated with 825 pounds of caustic soda if the caustic soda is used at a dosage of 15 ppm?
A. 4.4 MG
B. 5.9 MG
C. 6.6 MG
D. 7.0 MG
7. What is a water treatment plant's ferric sulfate dosage if the plant uses 2450 pounds of ferric sulfate to treat 12,500,000 gallons of water?
A. 17.2 mg/l
B. 23.5 mg/l
C. 30.7 mg/l
D. 48.6 mg/l
8. How many pounds of lime are needed to treat 10 MG of water with a lime dosage of 5 mg/l?
A. 310 lbs.
B. 507 lbs.
C. 471 lbs.
D. 417 lbs.
9. How many gallons of water will 3835 pounds of alum dose if the alum is used at a dosage of 65 ppm?
A. 4,731,955 gallons
B. 2,445,000 gallons
C. 7,074,341 gallons
D. 6,258,029 gallons
10. How many pounds of zinc orthophosphate will be needed to treat 32 million-gallons of water with a dosage of 1.4 mg/l?
A. 374 pounds
B. 320 pounds
C. 140 pounds
D. 260 pounds
ANSWERS: 1. B; 2. C; 3. D; 4. B; 5. A; 6. C; 7. B; 8. D; 9. C; 10. A