@PROFDOCDIGITALLIBRARIES
Wastewater Class 4 Exam Virginia| 100 questions| with
complete solutions Latest Updated Version Guide A+
In an electrical circuit, the grounding wire is indicated by which color?
Green
According to the Ohms Law, which electrical unit measures pressure?
Volts
According to the Ohms Law, which electrical unit measures resistance?
Ohms
According to the Ohms Law, which electrical unit measures current?
Amps
ST
How do you convert cubic feet to gallons?
Multiply by 7.48
How do you convert gallons to pounds?
O
Multiply by 8.34
Calculate the SVI of your aeration basin when your 30-minute settleable sample is 360 mL/L and your
average mixed liquor suspended solids concentration is 4000 mg/L.
IC
90
Solution:
360 x 1,000
= 90
4,000
What is the most widely used dechlorination agent in a conventional chlorine gas plant?
Sulfur Dioxide
What is the most prominent concern in failing to remove grit from the wastewater?
Excessive wear and damage on mechanical equipment
What is the chemical formula for Sulfuric Acid?
H2SO4
What is the ideal velocity in a grit channel, in feet per second?
, @PROFDOCDIGITALLIBRARIES
1 fps
Conventional pump packing should be:
Tightened down to a drip
In a primary clarifier, the expected performance for removing settleable solids is 90-95% removal. What
about the removal of suspended solids?
50%
When preparing a sample for laboratory analysis that involves acid and water, how should the sample
be poured?
Always pour the acid into the water
You are tasked with recording a manual flow sample in an open channel. Where will you position
yourself, relative to the weir, to record the most accurate measure of flow?
Behind the weir, 4 times the maximum head of the weir
Why must a positive displacement pump never be started against a closed discharge valve?
ST
Excessive pressure may damage the line, the pump, and the motor
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
O
Solution:
0.785 x 45 x 45 x 10 x 7.48 x 24
IC
= 2.038
1,420,000
What is the most common device for measuring flow in an open channel?
V-notch weir, then ultrasonic flowmeter.
You need to make an adjustment to your aeration basin, and foam is the only characteristic you have
data on. Over the last few days, the foam has become white, and billowy. What adjustment do you
make?
Decrease WAS
Over the last week, your mixed liquor color has changed from brown, to dark brown, to black. What
adjustment should you make?
Increase WAS
You receive a surge of high flow into your aeration basins, and as a result, you are developing an
increasing, billowy sludge blanket in your secondary settling tanks. What adjustment should you make?
Wastewater Class 4 Exam Virginia| 100 questions| with
complete solutions Latest Updated Version Guide A+
In an electrical circuit, the grounding wire is indicated by which color?
Green
According to the Ohms Law, which electrical unit measures pressure?
Volts
According to the Ohms Law, which electrical unit measures resistance?
Ohms
According to the Ohms Law, which electrical unit measures current?
Amps
ST
How do you convert cubic feet to gallons?
Multiply by 7.48
How do you convert gallons to pounds?
O
Multiply by 8.34
Calculate the SVI of your aeration basin when your 30-minute settleable sample is 360 mL/L and your
average mixed liquor suspended solids concentration is 4000 mg/L.
IC
90
Solution:
360 x 1,000
= 90
4,000
What is the most widely used dechlorination agent in a conventional chlorine gas plant?
Sulfur Dioxide
What is the most prominent concern in failing to remove grit from the wastewater?
Excessive wear and damage on mechanical equipment
What is the chemical formula for Sulfuric Acid?
H2SO4
What is the ideal velocity in a grit channel, in feet per second?
, @PROFDOCDIGITALLIBRARIES
1 fps
Conventional pump packing should be:
Tightened down to a drip
In a primary clarifier, the expected performance for removing settleable solids is 90-95% removal. What
about the removal of suspended solids?
50%
When preparing a sample for laboratory analysis that involves acid and water, how should the sample
be poured?
Always pour the acid into the water
You are tasked with recording a manual flow sample in an open channel. Where will you position
yourself, relative to the weir, to record the most accurate measure of flow?
Behind the weir, 4 times the maximum head of the weir
Why must a positive displacement pump never be started against a closed discharge valve?
ST
Excessive pressure may damage the line, the pump, and the motor
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
O
Solution:
0.785 x 45 x 45 x 10 x 7.48 x 24
IC
= 2.038
1,420,000
What is the most common device for measuring flow in an open channel?
V-notch weir, then ultrasonic flowmeter.
You need to make an adjustment to your aeration basin, and foam is the only characteristic you have
data on. Over the last few days, the foam has become white, and billowy. What adjustment do you
make?
Decrease WAS
Over the last week, your mixed liquor color has changed from brown, to dark brown, to black. What
adjustment should you make?
Increase WAS
You receive a surge of high flow into your aeration basins, and as a result, you are developing an
increasing, billowy sludge blanket in your secondary settling tanks. What adjustment should you make?
