WTO - Water Treatment Operator Water Treatment Math Questions and Answers

Question 1

A water treatment plant treats a flow of 7.0 MGD. If the desired dose for sodium hypochlorite is 3.0 mg/L, how many pounds of chemical will be required per day?

Accepted Answer

175.1 lbs/day

Answer

121.2 lbs/day

Answer

21.0 lbs/day

Answer

1,459.5 lbs/day

Question 2

A circular clarifier has a diameter of 80 feet and a water depth of 15 feet. If the plant flow is 4.0 MGD, what is the detention time in hours?

Accepted Answer

3.37 hours

Answer

1.34 hours

Answer

0.28 hours

Answer

6.78 hours

Question 3

A gravity filter has surface dimensions of 22 feet by 30 feet. If the filter is receiving a flow of 2,300 gallons per minute, what is the filter loading rate?

Accepted Answer

3.48 gpm/ft²

Answer

4.21 gpm/ft²

Answer

2.89 gpm/ft²

Answer

5.15 gpm/ft²

Question 4

An operator is calibrating a chemical feed pump. A calibration test shows that the pump delivered 750 mL in 3 minutes. What is the feed rate in gallons per day (gpd)?

Accepted Answer

66.1 gpd

Answer

135.5 gpd

Answer

26.5 gpd

Answer

95.1 gpd

Question 5

A pump must deliver 800 gpm against a total head of 120 feet. What is the required water horsepower (WHP)?

Accepted Answer

24.2 WHP

Answer

15.8 WHP

Answer

31.4 WHP

Answer

45.0 WHP

Question 6

A water plant uses 125 pounds of a chemical per day to treat a flow of 3.5 MGD. What is the calculated dosage in mg/L?

Accepted Answer

4.3 mg/L

Answer

5.6 mg/L

Answer

3.1 mg/L

Answer

2.9 mg/L