Waterwaster Class 4 Exam Virginia with Questions and Answers – 100% Solved
- ✔✔✔-
A circular tank is 45 feet in diameter and has a depth of 10 feet. What is the detention time in
hours when the flow is 1.42 MGD? - ✔✔✔-2 hours
Solution:
0.785 x 45 x 45 x 10 x 7.48 x 24
----------------------------------- = 2.038
1,420,000
A large number of amoebas would indicate what type of sludge? - ✔✔✔-Young sludge
A large number of rotifers would indicate what type of sludge? - ✔✔✔-Old sludge
A positive displacement sludge pump should never be placed into operation with the
_______________ closed. - ✔✔✔-Discharge valve
According to the Ohms Law, which electrical unit measures current? - ✔✔✔-Amps
According to the Ohms Law, which electrical unit measures pressure? - ✔✔✔-Volts
According to the Ohms Law, which electrical unit measures resistance? - ✔✔✔-Ohms
Among all the organisms in activated sludge, what percentage is bacteria? - ✔✔✔-95%
An active sludge in the aeration tank with an abundant available food supply will have a
relatively:
, Waterwaster Class 4 Exam Virginia with Questions and Answers – 100% Solved
High oxygen uptake and fast settling rate
High oxygen uptake and slow settling rate
Low oxygen uptake and fast settling rate
Low oxygen uptake and slow settling rate - ✔✔✔-High oxygen uptake and slow settling rate
An imhoff cone is used to? - ✔✔✔-Determine the amount of settleable solids
At what temperature does the BOD sample need to be preserved at? - ✔✔✔-At or below 6
degrees Celsius
Based upon the available data, what change should an operator make to achieve the optimum
organic loading?
Tanks available: 3
Tanks in service: 2
BOD concentration: 176 mg/L
Flow: 6.5 MGD
Tank diameter: 100 ft
Tank depth: 6 ft
The design organic loading rate is 200-300 lbs/1,000 cubic feet. - ✔✔✔-176 x 6.5 x 8.34 x 1000 /
0.785 x 100 x 100 x 6 x 2 tanks= 101
176 x 6.5 x 8.34 x .785 x 100 x 100 x 6 x 1 tank= 203
Take a tank out of service so that there is only one tank in service. 203 is within design rate.
- ✔✔✔-
A circular tank is 45 feet in diameter and has a depth of 10 feet. What is the detention time in
hours when the flow is 1.42 MGD? - ✔✔✔-2 hours
Solution:
0.785 x 45 x 45 x 10 x 7.48 x 24
----------------------------------- = 2.038
1,420,000
A large number of amoebas would indicate what type of sludge? - ✔✔✔-Young sludge
A large number of rotifers would indicate what type of sludge? - ✔✔✔-Old sludge
A positive displacement sludge pump should never be placed into operation with the
_______________ closed. - ✔✔✔-Discharge valve
According to the Ohms Law, which electrical unit measures current? - ✔✔✔-Amps
According to the Ohms Law, which electrical unit measures pressure? - ✔✔✔-Volts
According to the Ohms Law, which electrical unit measures resistance? - ✔✔✔-Ohms
Among all the organisms in activated sludge, what percentage is bacteria? - ✔✔✔-95%
An active sludge in the aeration tank with an abundant available food supply will have a
relatively:
, Waterwaster Class 4 Exam Virginia with Questions and Answers – 100% Solved
High oxygen uptake and fast settling rate
High oxygen uptake and slow settling rate
Low oxygen uptake and fast settling rate
Low oxygen uptake and slow settling rate - ✔✔✔-High oxygen uptake and slow settling rate
An imhoff cone is used to? - ✔✔✔-Determine the amount of settleable solids
At what temperature does the BOD sample need to be preserved at? - ✔✔✔-At or below 6
degrees Celsius
Based upon the available data, what change should an operator make to achieve the optimum
organic loading?
Tanks available: 3
Tanks in service: 2
BOD concentration: 176 mg/L
Flow: 6.5 MGD
Tank diameter: 100 ft
Tank depth: 6 ft
The design organic loading rate is 200-300 lbs/1,000 cubic feet. - ✔✔✔-176 x 6.5 x 8.34 x 1000 /
0.785 x 100 x 100 x 6 x 2 tanks= 101
176 x 6.5 x 8.34 x .785 x 100 x 100 x 6 x 1 tank= 203
Take a tank out of service so that there is only one tank in service. 203 is within design rate.
