Activated Sludge Treatment System Quiz
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Questions and Answers

What does MCRT refer to in an activated sludge system?

  • The average number of days a cell remains in the system (correct)
  • The maximum capacity of the activated sludge system
  • The pH level maintained in the activated sludge system
  • The minimum oxygen level required in the activated sludge system

    • Is activated sludge an anaerobic process?

  • Yes
  • No, it's a physical process
  • No, it's a chemical process
  • No, it's an aerobic process (correct)

    • What is the main purpose of secondary treatment in wastewater treatment?

  • To remove the organic content of the wastewater (correct)
  • To disinfect the wastewater
  • To remove the inorganic content of the wastewater
  • To adjust the pH level of the wastewater

    • What does SVI measure in the context of sludge volume?

    <p>The sludge volume that needs to be wasted</p> Signup and view all the answers

    Which statement about untreated wastewater bacteria is true?

    <p>Most bacteria are not harmful to humans and some are helpful in wastewater treatment</p> Signup and view all the answers

    Are ppm and % considered roughly equivalent for wastewater treatment calculations?

    <p>No, ppm is much larger than %</p> Signup and view all the answers

    In a trickling filter, recirculation helps prevent excessive sloughing. Is this statement:

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

    Is series operation of a trickling filter the preferred mode during very low temperature conditions in winter?

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

    Is the advantage of trickling filter over the activated sludge related to its BOD removal efficiency?

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

    Can hydrogen sulfide gas in a moist atmosphere result in corrosion of concrete structures?

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

    Can the presence of hydrogen sulfide always be detected by its characteristic odor?

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

    Will a well-operated primary clarifier remove between 90 and 95 percent of the influent settleable solids?

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

    Is it common for primary clarifiers to remove 80-85% of the BOD and 90-95% of the TSS?

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

    Are the only function of flights in a rectangular sedimentation tank to push the settled sludge towards the hopper?

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

    Is detention time the time required to fill a tank at a given flow?

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

    Is primary treatment a process that allows substances that will settle or float to be separated from the wastewater being treated?

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

    Does raw sludge pumped from a primary clarifier generally contain about 3% to 6% total solids?

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

    One misconception is that typical domestic wastewater BOD content is about 2000mg/l. Is this statement:

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

    What test is used to determine the organic matter found in the mixed liquor?

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

    The four (4) basic components of every activated sludge treatment system are:

    <p>Aeration, clarification, return sludge and waste sludge</p> Signup and view all the answers

    Which of the following statements is not true regarding a wastewater collection system:

    <p>A sewer is designed to allow the waste to flow at a rate of approximately 1 ft/sec.</p> Signup and view all the answers

    Velocity of flow in sewers is usually expressed in terms of:

    <p>Feet per second</p> Signup and view all the answers

    One of the reasons that air should be excluded from anaerobic digesters is because:

    <p>the entrance of air mixed with the gas produced in the digester could create an explosive mixture</p> Signup and view all the answers

    The fundamental purpose of disinfection is to:

    <p>Destroy pathogenic organisms</p> Signup and view all the answers

    The difference between the amount of chlorine added and the amount of chlorine remaining after the contact period is referred to as:

    <p>the chlorine demand</p> Signup and view all the answers

    The ultimate measure of the effectiveness of chlorination in disinfection is:

    <p>effective reduction of the coliform count</p> Signup and view all the answers

    TKN is the measure of:

    <p>Ammonia/Ammonium+Organic Nitrogen</p> Signup and view all the answers

    Sludge with a specific gravity of 1.1 will weigh:

    <p>9.17lbs/gal</p> Signup and view all the answers

    pH increases during the day, and decreases at night in a properly operating facultative pond due to:

    <p>the highest consumption of CO2 during daytime</p> Signup and view all the answers

    What is a common problem associated with trickling filters?

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

    What are the primary organisms responsible for treating wastewater in the trickling filter process?

    <p>Aerobic bacteria</p> Signup and view all the answers

    What does 'sloughing' from a trickling filter refer to?

    <p>The periodic discharge of large quantities of slime growth with the filter effluent.</p> Signup and view all the answers

    What is the solids concentration of sludge with a sludge density of 7%?

    <p>70,000 mg/l</p> Signup and view all the answers

    What is the surface area of a cylindrical tank 80 feet in diameter and 25 feet in height (cylindrical part surface area only)?

    <p>6,280 sq. ft</p> Signup and view all the answers

    Calculate the VS loading to the digester in lbs/day if 10,000 cu. ft of sludge containing 4.8% TS with an average VS content of 82%.

    <p>42,756 lbs/day</p> Signup and view all the answers

    What is the detention time for a sedimentation tank that is 48 feet wide, 210 feet long, and 9 feet deep with a flow of 5 MGD?

    <p>3.25 hours.</p> Signup and view all the answers

    What is the weir loading for a sedimentation tank with an outlet weir 480 ft long and a flow of 5 MGD?

    <p>10,420 gpd/ft</p> Signup and view all the answers

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