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1. Which activated sludge process re-aerates RAS before being introduced into the influent wastewater?

   1.   ?    Step feed
   2.   ?    Complete mix
   3.   ?    Contact stabilization
   4.   ?    Plug Flow

2. Where is the highest demand for oxygen in a plug flow aeration tank?

   1.   ?    At the effluent weir
   2.   ?    In the middle of the tank
   3.   ?    Equally throughout the tank
   4.   ?    In the beginning of the tank

3. Which aeration mode is intended to dilute high demand influent loadings?

   1.   ?    Plug flow
   2.   ?    Step feed
   3.   ?    Complete mix
   4.   ?    Contact stabilization

4. Which flow stream is typically the most concentrated (ppm) in the contact stabilization process?

   1.   ?    RAS
   2.   ?    Stabilizer tank
   3.   ?    Contact tank
   4.   ?    Influent wastewater

5. Which growth phase does the stabilizer tank of the contact stabilization process typically operate in?

   1.   ?    Log growth to declining
   2.   ?    Declining growth to endogenous
   3.   ?    Endogenous respiration to log
   4.   ?    Filamentous

6. Which growth phase is predominant in extended aeration?

   1.   ?    Declining growth
   2.   ?    Endogenous respiration
   3.   ?    Log growth
   4.   ?    Filamentous

7. Which growth phase provides the best oxygen utilization efficiency . . . lowest pounds of oxygen per pound of CBOD₅ converted?

   1.   ?    Endogenous respiration
   2.   ?    Declining growth
   3.   ?    Extended aeration
   4.   ?    Log growth

8. What is a typical SRT in the log growth phase?

   1.   ?    High – above 15 days
   2.   ?    Moderate – about 7 days
   3.   ?    Low – below 3 days
   4.   ?    It can’t be measured

9. Which conditions best describe potential filamentous over-growth (bulking)?

   1.   ?    High D.O. and low food
   2.   ?    High D.O. and high F/M ratio
   3.   ?    Low D.O. and low F/M ratio
   4.   ?    Zero D.O. and low SRT

10. What is typically the limiting factor in sustaining growth of microorganisms in the declining growth phase?
    

    1.   ?    Oxygen
    2.   ?    Time
    3.   ?    Food
    4.   ?    Volatile bugs

11. What is a typical F/M ratio range in the declining growth phase?
    

    1.   ?    0.7 to 1.0
    2.   ?    0.2 to 0.5
    3.   ?    0.05 to 0.15
    4.   ?    0.6 to 0.75

12. What is a typical F/M ratio range in the endogenous respiration growth phase?

    1.   ?    0.7 to 1.0
    2.   ?    0.2 to 0.5
    3.   ?    0.05 to 0.15
    4.   ?    0.6 to 0.75

13. What is the typical oxygen utilization condition in the endogenous respiration growth phase?

    1.   ?    The utilization of oxygen is at its best
    2.   ?    The demand for oxygen is low
    3.   ?    The demand for oxygen is not affected by growth phase
    4.   ?    The utilization of oxygen is at its poorest

14. What typically happens to microorganisms when they are subjected to an excessive supply of food (CBOD₅)?

    1.   ?    They grow and multiply
    2.   ?    Their growth slows down
    3.   ?    The demand for oxygen decreases
    4.   ?    The sludge yield decreases

15. Which parameter best describes the balance of food to microorganisms?

    1.   ?    SRT
    2.   ?    F/M
    3.   ?    MCRT
    4.   ?    GSA

16. Which conditions typically generate a larger volume of new cellular growth?

    1.   ?    High F/M with low D.O.
    2.   ?    Low F/M with high D.O.
    3.   ?    Low F/M with low D.O.
    4.   ?    High F/M with high D.O.

17. Which age parameter utilizes the pounds/day of influent TSS entering the aeration tank?

    1.   ?    GSA
    2.   ?    SRT
    3.   ?    MCRT
    4.   ?    F/M ratio

18. Which condition may indicate too much food is still available in the MLSS leaving the aeration tank?

    1.   ?    Low OUR/RR in aeration inlet
    2.   ?    High OUR/RR in aeration inlet
    3.   ?    Low OUR/RR in aeration outlet
    4.   ?    High OUR/RR in aeration outlet

19. What test result is necessary to convert OUR to RR?

    1.   ?    CBOD₅
    2.   ?    MLSS
    3.   ?    MLVSS
    4.   ?    D.O.

20. Which best describes sludge volume index?

    1.   ?    Numerical indicator of bug population
    2.   ?    Volume-to-weight ratio of mixed liquor
    3.   ?    Volume-to volume ratio of mixed liquor
    4.   ?    Removal efficiency of BOD