32 Questions
What step comes after substituting given values from the problem statement?
Calculate the answer
What should be done if the instructor needs to understand the work presented in math worksheets?
Organize the work clearly
What is the purpose of most wastewater treatment plants?
To have a separate industrial-wastewater collection system
What can result in corrosion of concrete structures in a moist atmosphere?
Hydrogen sulfide gas
When can grab or composite samples be used interchangeably?
When they are most convenient and safest for all laboratory tests
In a primarily domestic wastewater treatment plant, is the influent wastewater BOD always greater than its chemical oxygen demand?
False
Is coliform testing typically conducted on a grab sample?
True
Is a lateral the largest sewer line that brings the wastewater to the treatment plant?
False
At a primarily domestic wastewater treatment plant, is the influent wastewater BOD always less than its chemical oxygen demand?
True
Which of the following statements about pre-aeration and settling in a primary clarifier is true?
Pre-aeration has no influence on the degree of settling
What happens if a grit chamber has a faster flow velocity than recommended?
Increased collection of organic matter in the grit
What would be the result of an inadequate detention time in a primary clarifier?
Increased solids pumping to digesters
In a primarily domestic wastewater treatment plant, is the influent wastewater BOD always less than its chemical oxygen demand?
Influent BOD can be greater or less than its chemical oxygen demand
What is the average specific gravity of sludge solids in wastewater?
1.2 ; this means they are 20% heavier than water
What does the weir overflow rate of a primary clarifier measure?
The overflow rate in gallons per day per square feet
What do gas bubbles rising to the surface in a primary clarifier indicate?
Poor settling of the sludge in the unit
What do gas bubbles rising to the surface in a primary clarifier NOT indicate?
The sludge in the unit is undergoing proper settling
What does a properly designed primary clarifier remove 90 percent of?
Settleable Solids
What does a positive ORP indicate in water treatment?
Oxidative
What substance is grit mostly composed of in wastewater treatment?
Plastics
What is NOT typically removed by a properly designed primary clarifier?
Dissolved Oxygen
What is the main objective of primary sedimentation?
Settleable solids and floatables
What could cause significant gas bubbles formation on the water surface of a primary clarifier?
Too short of detention time
What is considered a normal detention time for a primary clarifier?
6 hours
What is likely to result from an inadequate detention time in a primary clarifier?
Poor separation of settleable solids
What is the main objective of primary sedimentation?
Settleable solids and floatables
What would be considered normal detention time for a primary clarifier?
12 hours
What could observation of significant gas bubbles formation on the water surface of a primary clarifier indicate?
Sludge decomposition due to inadequate sludge withdrawal
What can result in sludge gasification at a wastewater treatment plant?
Too short of detention time in the primary clarifier
What is the pounds per day BOD in the primary effluent after 47% BOD removal of a 4 MGD flow with 350 mg/l influent BOD concentration?
6,824
What is the flow velocity in feet per minute for a channel that is 3 ' wide x 4 ' deep, with a flow of 7.5 MGD and a depth of flow of 15 inches?
8.2
What is the surface loading rate (gal/(day-sq.ft)) for a 15 MGD flow in a 105 ft diameter primary sedimentation tank operating at a water depth of 20 ft?
1,733
Learn how to approach math problems effectively with this quiz's step-by-step instructions. From drawing a sketch and identifying given values to calculating the answer and boxing it with the correct units, these guidelines will help you tackle math problems accurately.
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