| Question - 1 of 10 | a | b | c | d |
| The operation log shows the color of the liquid in the aeration tank has changed from brown to a reddish brown, there is poor separation of the solids in the 30 - minute settleability test and the supernatant is cloudy, fluffy sludge hangs in it. There is a brown slime in the settling tank. The indications show that ; | The aeration tank is being under - aerated | The aeration tank is being over - aerated | The plant is organically overloaded | The plant is in septic condition |
| Question - 2 of 10 | a | b | c | d |
| Your first action should be ; | Reduce the air supply as much as possible even to a point of temporary shut - down | Increase air supply to maximum | Discontinue operating the surface skimmer | Remove excess solids from the plant |
| Question - 3 of 10 | a | b | c | d |
| Another action you could take is ; | Decrease the rate of returning sludge | Discontinue operating the surface skimmer | Squeegee the settling tank walls and baffles | Increase the rate of returning sludge |
| Question - 4 of 10 | a | b | c | d |
| This type of problem would usually occurs when the plant is ; | Organically over - loaded | Hydraulically over - loaded | Organically under - loaded | In good operating condition |
| Question - 5 of 10 | a | b | c | d |
| Another action you could take to combat the effects of over - aeration is ; | Remove excess solids from the plant | In extreme cases you can add manure to the aeration tank | In extreme cases you can add acid to the aeration tank | In extreme cases you can add lime to the aeration tank |
| Question - 6 of 10 | a | b | c | d |
| The most common underloading case is ; | During the wet season due to storm water infiltration into sewer pipes | When a plant has been sized to handle a future flow which has not developed | When industrial waste is being discharged into the sewer | Organic overloading |
| Question - 7 of 10 | a | b | c | d |
| Another common problem in a new plant is ; | High acid content | Excessive foaming in the aeration tank | High alkaline content | Excessive lose of solids from the plant |
| Question - 8 of 10 | a | b | c | d |
| A corrective action for excessive foaming would be ; | Discontinue operating the surface skimmer | Increase the air supply to the aeration tank | Discontinue operating the foam control spray system | Continuous operation of the foam control spray system |
| Question - 9 of 10 | a | b | c | d |
| If the plant was not equipped with a spray system you could control the foam by ; | Adding lime to the aeration tank | Adding acid to the aeration tank | Adding a small amount of a defoaming agent to the aeration tank | Adding high amount of diesel motorine or kerosene to the aeration tank |
| Question - 10 of 10 | a | b | c | d |
| What about the color of the foam ? | Brown | Black | White | Gray |
