Water Solutions You Can Trust

20 multiple-choice questions along with their answers, focused on Level One water treatment math concepts

  1. If a tank holds 2,500 gallons and it is 60% full, how many gallons of water are in the tank?
  • A) 1,250 gallons
  • B) 1,500 gallons
  • C) 2,000 gallons
  • D) 1,000 gallons
  • Answer: B) 1,500 gallons
  1. What is the dosage rate (mg/L) if 500 grams of chlorine are added to 10,000 liters of water?
  • A) 0.05 mg/L
  • B) 5 mg/L
  • C) 50 mg/L
  • D) 500 mg/L
  • Answer: C) 50 mg/L
  1. A pipe with a diameter of 8 inches is flowing at a rate of 300 gallons per minute (GPM). What is the flow rate in cubic feet per second (CFS)?
  • A) 0.67 CFS
  • B) 0.89 CFS
  • C) 1.34 CFS
  • D) 1.68 CFS
  • Answer: A) 0.67 CFS
  1. If a pump operates at 80% efficiency and it requires 10 kW to operate, what is the actual power output?
  • A) 12.5 kW
  • B) 8 kW
  • C) 6.25 kW
  • D) 9 kW
  • Answer: B) 8 kW
  1. How many pounds of a chemical are needed to treat 1 million gallons of water if the dosage required is 3 mg/L?
  • A) 25 pounds
  • B) 37.5 pounds
  • C) 50 pounds
  • D) 62.5 pounds
  • Answer: B) 25 pounds
  1. A sedimentation basin has a surface area of 2000 square feet and a flow rate of 2 million gallons per day (MGD). What is the surface loading rate in gallons per square foot per day?
  • A) 1000 gal/ft²/day
  • B) 800 gal/ft²/day
  • C) 600 gal/ft²/day
  • D) 500 gal/ft²/day
  • Answer: D) 1000 gal/ft²/day
  1. If a filter has a backwash rate of 15 gallons per minute (GPM) per square foot and the filter area is 25 square feet, what is the total backwash flow rate?
  • A) 250 GPM
  • B) 375 GPM
  • C) 400 GPM
  • D) 450 GPM
  • Answer: B) 375 GPM
  1. What is the volume of a cylindrical tank with a diameter of 10 feet and a height of 20 feet?
  • A) 1,570 cubic feet
  • B) 1,000 cubic feet
  • C) 1,570 gallons
  • D) 2,000 gallons
  • Answer: A) 1,570 cubic feet
  1. If a treatment plant has an influent BOD concentration of 200 mg/L and an effluent BOD concentration of 20 mg/L, what is the percent removal efficiency?
  • A) 80%
  • B) 85%
  • C) 90%
  • D) 95%
  • Answer: C) 90%
  1. A rectangular clarifier is 50 feet long, 20 feet wide, and has a water depth of 10 feet. What is its volume in cubic feet?
    • A) 5,000 cubic feet
    • B) 10,000 cubic feet
    • C) 15,000 cubic feet
    • D) 20,000 cubic feet
    • Answer: B) 10,000 cubic feet
  2. If a tank must be drained at a rate of 200 GPM and holds 6,000 gallons, how long will it take to drain completely?
    • A) 15 minutes
    • B) 20 minutes
    • C) 25 minutes
    • D) 30 minutes
    • Answer: D) 30 minutes
  3. If a flow meter measures 5 cubic feet per second (CFS), what is the equivalent flow rate in gallons per minute (GPM)?
    • A) 2,244 GPM
    • B) 3,372 GPM
    • C) 4,488 GPM
    • D) 6,720 GPM
    • Answer: C) 3,372 GPM
  4. What is the hydraulic loading rate of a clarifier with a surface area of 300 square feet and a flow rate of 0.5 MGD?
    • A) 1,250 gal/ft²/day
    • B) 1,667 gal/ft²/day
    • C) 2,500 gal/ft²/day
    • D) 5,000 gal/ft²/day
    • Answer: A) 1,667 gal/ft²/day
  5. If the velocity of water in a pipe is 6 feet per second and the pipe’s diameter is 1 foot, what is the flow rate in cubic feet per second (CFS)?
    • A) 4.71 CFS
    • B) 6 CFS
    • C) 7.85 CFS
    • D) 9.42 CFS
    • Answer: B) 6 CFS
  6. A pump lifts water to a height of 100 feet with an efficiency of 70%. If the pump supplies 50 horsepower, what is the actual energy used to lift the water?
    • A) 35 horsepower
    • B) 50 horsepower
    • C) 70 horsepower
    • D) 100 horsepower
    • Answer: A) 35 horsepower
  7. If a tank holds 20,000 liters and it is 75% full, how many liters of water are in the tank?
    • A) 10,000 liters
    • B) 12,500 liters
    • C) 15,000 liters
    • D) 17,500 liters
    • Answer: C) 15,000 liters
  8. What is the detention time in hours for a sedimentation basin with a volume of 60,000 cubic feet and an influent flow rate of 1.5 MGD?
    • A) 8 hours
    • B) 10 hours
    • C) 12 hours
    • D) 16 hours
    • Answer: C) 8 hours
  9. If the flow rate is 500 gallons per minute and the tank has a volume of 30,000 gallons, what is the hydraulic retention time in hours?
    • A) 0.5 hours
    • B) 1 hour
    • C) 2 hours
    • D) 3 hours
    • Answer: C) 1 hour
  10. A pipeline has a diameter of 12 inches and is 1 mile long. If the flow rate is 3 feet per second, how many gallons per minute (GPM) are flowing through the pipe?
    • A) 8,000 GPM
    • B) 9,600 GPM
    • C) 10,800 GPM
    • D) 12,000 GPM
    • Answer: D) 10,800 GPM
  11. If a chemical dosage of 2 mg/L is required and the flow rate is 1,000 GPM, how many pounds of chemical are needed per day?
    • A) 20 pounds
    • B) 24 pounds
    • C) 36 pounds
    • D) 48 pounds
    • Answer: C) 24 pounds

Kash Kattel

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