Wastewater Operator Workshop Mission Math

What is the equivalent in mgd for 78,850 gpd?
1. 0.0007885 mgd
2. 0.7885 mgd
3. 0.07885 mgd
4. 0.007885 mgd
What is the equivalent in mgd for 35,000 gpd?
1. 0.00035 mgd
2. 1.35 mgd
3. 0.035 mgd
4. 0.35 mgd
What is a typical loading equivalent for TSS in domestic wastewater?
1. About 0.17 lbs/person/day
2. About 0.2 lbs/person/day
3. About 300 gal/person/day
4. About 200 mg/l/person/day
What does one cubic foot of water weigh at 4°C?
1. 7.48 pounds
2. 8.34 pounds
3. 3.14159 pounds
4. 62.4 pounds
What is the detention time of a chlorine contact chamber that is 100 feet long, 15 feet wide, 9 feet deep, and has a plant flow rate of 4.2 mgd?
1. About 2 hours
2. About 76 minutes
3. About 35 minutes
4. About 15 minutes
If your plant has a flow rate of 1.25 mgd, a chlorine demand of 7.5 mg/l, and you maintain a chlorine residual of 1.5 mg/l, how many lbs/day of chlorine will be used?
1. 93.8 lbs/day
2. 78.2 lbs/day
3. 62.6 lbs/day
4. 52.1 lbs/day
What will be the volume of a tank if the flow entering is 5 mgd and the detention time is 1.5 hours
1. 583,000 gals
2. 1.2 mg
3. 0.3957 mg
4. 312,500 gals
How many pounds of solids are in a tank that is 100 feet long, 30 feet wide, 14 feet deep, and the MLSS concentration is 3,500 mg/l?
1. 19,170 lbs
2. 350 lbs
3. 1,226 lbs
4. 9,170 lbs
Given the following data, what is the detention time of the sludge blanket in this gravity thickener?
• 50 ft. diameter
• 3 ft. sludge blanket depth
• 4 ft. cone depth
• 100 kgpd thickened sludge removed
1. 30.6 hours
2. 15.3 hours
3. 7.6 hours
4. 22.9 hours
What is the HRT in days of an aerobic digester given the following data:
• 75 ft. diameter tank
• 20 ft. deep
• TWAS feed 15,500 gpd
• Tank depth averaged 85%
1. 62.6 days
2. 31.3 days
3. 23.5 days
4. 36.2 days
What is the aeration tank MLVSS concentration?
• Aeration MLSS is 2,500 mg/l
• Aeration MLSS is 77% Volatile
1. 3,500 mg/l
2. 3,000 mg/l
3. 1,925 mg/l
4. 2,625 mg/l
What is the percent BOD₅ removal efficiency in this plant?
• Influent CBOD₅ is 200 mg/l
• Effluent CBOD₅ is 2.5 mg/l
1. 98.8%
2. 100%
3. 89.6%
4. 99.0%
What is the solids loading rate on the secondary clarifiers?
• Two (2) Secondary Clarifiers, Each @ 100 ft. Diameter and 14 ft. Deep
• Aeration MLSS is 2,500 mg/l
• Plant Flow is 5.75 mgd
• RAS Rate is 65% of Q
1. 12.6 lbs/day/ft²
2. 8.6 lbs/day/ft²
3. 4.7 lbs/day/ft²
4. 9.9 lbs/day/ft²
What is the total length of weir for the secondary clarifiers?
• Two (2) Secondary Clarifiers, Each @ 100 ft. Diameter and 14 ft. Deep
• Each Secondary Clarifier has a Single Weir Around the Tank's Circumference
1. 628 feet
2. 912 feet
3. 314 feet
4. 157 feet
What is the total volume of the gravity thickener, including the cone volume, given the following data:
• 50 ft. diameter
• 12 ft. SWD
• 3 ft. sludge blanket depth
• 4 ft. cone depth
1. 176,154 gals
2. 19,578 gals
3. 324,578 gals
4. 195,777 gals
What is the consumption of chlorine used in 30 days if the flow rate is 2,500 gpm, and the dose rate is 8.5 mg/l?
1. 255 pounds
2. 7,661 pounds
3. 10,219 pounds
4. 8,824 pounds
What is the moisture content of a sludge sample that measures 5.25% total solids?
1. 5.25%
2. 19%
3. .05%
4. 94.75%
Given the following data, what level of TKN has been removed in this BNR plant?
• Influent TKN is 25.5 mg/l
• Effluent TKN is 1.5 mg/l
• Biology has taken-up 2.0 mg/l TKN
1. 24.0 mg/l
2. 22.0 mg/l
3. 26.0 mg/l
4. 38.25 mg/l
Given the following data, what is the solids loading rate of this DAF unit?
• DAF tank is 80 feet long, 16 feet wide, and 12 feet deep
• Sludge feed rate 55 gpm for 750 mins/day
• Sludge feed concentration is 8,000 mg/l
1. 1.2 lbs/day/ft²
2. 3.6 lbs/day/ft²
3. 0.46 lbs/day/ft²
4. 2.1 lbs/day/ft²
What does the following formula represent?
OUR, mg/l/hr ÷ TS, gm/l = mg/hr/gm
1. Oxygen Uptake Rate
2. SOUR
3. SVI
4. Fecal coliform

Wastewater Operator Workshop Mission Math

Practice QuizBrought to you free of charge by RoyCEU.com

Practice Quiz
Brought to you free of charge by RoyCEU.com