Waste Water Ch.11

  1. The ratio of food to organisms is a primary control in theactivated sludge process.
  2. Activated sludge forms a lacy network or floc mass that entrapsmany materials not used as food.
  3. The activated sludge process is incapable of handling theminor variations in flows or wastewater characteristics andproduce the desired quality of effluent.
  4. Collection system maintenance activities can affect treatmentplant operation.
  5. Mechanical aeration devices are the most common type ofaeration system used in the activated sludge process.
  6. For your own safety and to avoid damaging equipment,always read the manufacturers' manuals and thoroughlyunderstand them before operating or maintaining any pieceof equipment.
  7. Before starting any blower, be sure all inlet and dischargevalves are closed throughout the system.
  8. To check out pumps, first lock out and tag the pump motor at the power panel so it cannot be started.
  9. A thin sludge in a secondary clarifier will require a lower return flow percentage than a thick sludge.
  10. In the activated sludge treatment process, the warmer the weather the less active the organisms, so the sludge age can be lowered by reducing the MLSS (mixed liquor suspended solids).
  11. Less air will be required when aeration tank solids increase in concentration and activity.
  12. The mixed liquor volatile suspended solids (MLVSS) is a measure of the organisms in the aerator available to treat the incoming waste.
  13. At an activated sludge plant, the sight, smell, and touch observations often are the first indications that problems are developing and frequently offer indications of appropriate corrective action.
  14. An activated sludge plant can accept quite a shock load now and then without adverse effects to the system, but it cannot survive a continuous series of shock loads.
  15. Rising sludge is the same as bulking sludge.
  16. Always read and understand manufacturers' literature before starting, operating, maintaining, or shutting down equipment.
  17. Step-feed aeration distributes the oxygen demand from the waste water over the entire aerator instead of concentrating it at the outlet end.
  18. The flexibility of sequencing batch reactors is shown by their ability to achieve nitrogen and phosphorus removal with simple operational modifications.
  19. Since there are no continuous flows through a sequencing batch reactor (SBR), there is little opportunity for solids losses.
  20. The presence of stalked ciliates indicates a stable activated sludge process that produces a low turbidity effluent.
  21. What are filamentous organisms?
    Organisms that grow in a thread or filamentous form
  22. What is the purpose of air filters?
    To remove dust and dirt from air before it is compressedand sent to various plant processes
  23. Why is the discharge line from the blower equipped with an air relief valve?
    To protect the blower from excessive back pressure andoverload
  24. What are the purposes of air header valves?
    To adjust the air flow to the header assembly and toblock the air flow to the assembly when servicing theheader or diffusers
  25. Why should flow control gates on aeration tanks be painted?
    For rust and corrosion protection
  26. What problem can develop if the base plate nuts or bolts become loose on a blower (compressor)?
    The whole alignment will be thrown out on start-up
  27. How can an excellent effluent be produced by the activatedsludge process
    The operator must have a plan of operation or an operationalstrategy and understand how the microorganismsremove wastes from the water being treated
  28. What is a quick way to determine the quality of a plant effluent
    The turbidity test
  29. Why does an operator need to keep accurate records at an activated sludge plant?
    To find the desirable operating range in terms of efficiencyof waste removal and cost of operation
  30. What is flocculation?
    The gathering together of fine particles after coagulationto form larger particles by a process of gentle mixing
  31. How can septic sludge be produced?
    When any type of sludge remains too long in suchplaces as hoppers and channels
  32. Constructing a sequencing batch reactor (SBR) plant usuallycosts less than a conventional activated sludge plantdue to the elimination of which item
    Secondary clarifiers
  33. Why should samples collected for microscopic observation be collected when the Sludge Volume Index (SVI) grab sample is taken?
    To correlate microscopic observations with changes inthe SVI
  34. Where should a micro sample be collected in an aeration tank?
    Where the microorganisms (bugs) should be hungry
  35. When waste water enters an activated sludge plant, the activated sludge. processes remove which pollutants?
    • 1. Coarse or heavy solids (grit)
    • 2. Debris, such as roots, rags, and boards
    • 3. Floatable and settleable material
  36. For the activated sludge process to work properly, the operator must control which items?
    • Dissolved oxygen in the aeration tanks
    • Number of organisms
    • Treatment time
  37. Which items are the sources of variations that affect the operation of the activated sludge plant?
    • Changes in collection system flows
    • Changes in waste water characteristics
    • In-plant operational variables
  38. What are the purposes of aeration in the activated sludgeprocess
    • To provide dissolved oxygen
    • To provide mixing of the mixed liquor and wastewaterin the aeration tank
  39. What information should be included on a lockout tag attachedto an aerator power breaker
    • The date the aerator was locked out
    • The name of the person who locked out the aerator
  40. What are the main reasons an operator should completely check a new plant's equipment and structures before start up?
    • To be reasonably sure that everything will function properly when the plant is put into service
    • To familiarize the operator with plant equipment and locations of piping
  41. Why is the proper operation ol equipment important? Becauseproper operation
    • Helps prevent operators from being injured
    • Prolongs the life of equipment
    • Reduces the cost of repairs and replacement
  42. When checking out a new activated sludge plant, whichitems should be checked when inspecting the secondaryclarifiers?
    1. 'Clarifier tank for sand and debris12. Control gates for operationI 3. Inlet baffles and discharge weirs for levelI 4. Scum control mechanismIs. Squeegee blades on the collector plows for proper distancefrom the floor of the tank
  43. If the return sludge rate is too low in an activated sludge plant, which undesirable conditions may develop?
    • Accumulation of sludge in the clarifier creates a deep sludge blanket, which will allow solids to escape in the effluent
    • If aeration is sufficient to produce nitrate in the aeration tanks, denitrification may occur resulting in rising sludge and subsequent effluent solids
    • Septic sludge could develop if the detention time in thesecondary clarifier is too long
  44. Which daily observations should be recorded by the operators at an activated sludge plant?
    • Aeration tank-turbulence, color, and amount of surface foam and scum
    • Influent-color and level of inflow
    • Secondary clarifier-effluent clear or turbid, type of solids on surface, and influent
  45. When the lab data varies widely from one day to the next,which items should be checked
    • Lab procedures for errors
    • Sampling location
    • Time samples were collected
  46. Which problems may be caused by septic sludge?
    • Septic sludge causes foul odors
    • Septic sludge rises slowly
    • Septic sludge sometimes rises in clumps
    • Small amounts of septic sludge can upset an aerator
  47. Sludge going septic in a secondary clarifier may develop from which causes?
    • Clarifier collection mechanism is turned off, thus the sludge is not being moved to the draw-off hopper
    • Return sludge pump is off or a valve is closed
    • Return sludge rate is too low, thus holding the solids inthe final clarifier too long and allowing them to becomeseptic
    • Sludge draw-off lines are plugged, obstructed, or usedinfrequently
  48. Which items contribute to abnormal conditions in the operation of air headers?
    • Normal deterioration
    • Upward water current drag forces exerted on the header
    • Vibration
  49. What items are advantages of the contact stabilization system with its off-scream reservoir of organisms in an aeration tank?
    • Avoids a complete kill of microorganisms when toxic wastes reach the plant
    • Avoids a complete solids wash-out when high flowsoccur
  50. Which types of microorganisms are typically present in an activated sludge mixed culture of microorganisms?
    • Algae
    • Rotifers
  51. Which microorganisms would be expected to predominate in a good settling activated sludge?
    • Free-swimming ciliates
    • Stalked ciliates
Card Set
Waste Water Ch.11
flash cards for the waste water class c test for florida