WUS 080 Mid-term Math Quiz Instructions
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Questions and Answers

What step comes after substituting given values from the problem statement?

  • Draw a sketch of the problem and write down the given values and identify unknown value/s
  • Box the answer with the correct units
  • Calculate the answer (correct)
  • Write down the formula required to solve the problem

    • What should be done if the instructor needs to understand the work presented in math worksheets?

  • Organize the work clearly (correct)
  • Submit multiple images of different sections
  • Use complex mathematical notations
  • Skip labeling the problem numbers

    • What is the purpose of most wastewater treatment plants?

  • To treat domestic sewage only
  • To treat industrial waste only
  • To have a separate industrial-wastewater collection system (correct)
  • To collect industrial waste only

    • What can result in corrosion of concrete structures in a moist atmosphere?

    <p>Hydrogen sulfide gas</p> Signup and view all the answers

    When can grab or composite samples be used interchangeably?

    <p>When they are most convenient and safest for all laboratory tests</p> Signup and view all the answers

    In a primarily domestic wastewater treatment plant, is the influent wastewater BOD always greater than its chemical oxygen demand?

    <p>False</p> Signup and view all the answers

    Is coliform testing typically conducted on a grab sample?

    <p>True</p> Signup and view all the answers

    Is a lateral the largest sewer line that brings the wastewater to the treatment plant?

    <p>False</p> Signup and view all the answers

    At a primarily domestic wastewater treatment plant, is the influent wastewater BOD always less than its chemical oxygen demand?

    <p>True</p> Signup and view all the answers

    Which of the following statements about pre-aeration and settling in a primary clarifier is true?

    <p>Pre-aeration has no influence on the degree of settling</p> Signup and view all the answers

    What happens if a grit chamber has a faster flow velocity than recommended?

    <p>Increased collection of organic matter in the grit</p> Signup and view all the answers

    What would be the result of an inadequate detention time in a primary clarifier?

    <p>Increased solids pumping to digesters</p> Signup and view all the answers

    In a primarily domestic wastewater treatment plant, is the influent wastewater BOD always less than its chemical oxygen demand?

    <p>Influent BOD can be greater or less than its chemical oxygen demand</p> Signup and view all the answers

    What is the average specific gravity of sludge solids in wastewater?

    <p>1.2 ; this means they are 20% heavier than water</p> Signup and view all the answers

    What does the weir overflow rate of a primary clarifier measure?

    <p>The overflow rate in gallons per day per square feet</p> Signup and view all the answers

    What do gas bubbles rising to the surface in a primary clarifier indicate?

    <p>Poor settling of the sludge in the unit</p> Signup and view all the answers

    What do gas bubbles rising to the surface in a primary clarifier NOT indicate?

    <p>The sludge in the unit is undergoing proper settling</p> Signup and view all the answers

    What does a properly designed primary clarifier remove 90 percent of?

    <p>Settleable Solids</p> Signup and view all the answers

    What does a positive ORP indicate in water treatment?

    <p>Oxidative</p> Signup and view all the answers

    What substance is grit mostly composed of in wastewater treatment?

    <p>Plastics</p> Signup and view all the answers

    What is NOT typically removed by a properly designed primary clarifier?

    <p>Dissolved Oxygen</p> Signup and view all the answers

    What is the main objective of primary sedimentation?

    <p>Settleable solids and floatables</p> Signup and view all the answers

    What could cause significant gas bubbles formation on the water surface of a primary clarifier?

    <p>Too short of detention time</p> Signup and view all the answers

    What is considered a normal detention time for a primary clarifier?

    <p>6 hours</p> Signup and view all the answers

    What is likely to result from an inadequate detention time in a primary clarifier?

    <p>Poor separation of settleable solids</p> Signup and view all the answers

    What is the main objective of primary sedimentation?

    <p>Settleable solids and floatables</p> Signup and view all the answers

    What would be considered normal detention time for a primary clarifier?

    <p>12 hours</p> Signup and view all the answers

    What could observation of significant gas bubbles formation on the water surface of a primary clarifier indicate?

    <p>Sludge decomposition due to inadequate sludge withdrawal</p> Signup and view all the answers

    What can result in sludge gasification at a wastewater treatment plant?

    <p>Too short of detention time in the primary clarifier</p> Signup and view all the answers

    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?

    <p>6,824</p> Signup and view all the answers

    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?

    <p>8.2</p> Signup and view all the answers

    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?

    <p>1,733</p> Signup and view all the answers

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