| Question - 1 of 10 | a | b | c | d |
| The operation log shows the sludge blanket in the settling tank is rising and the amount of solids at the 30 - minute settleability test carried out using the "Imhoff" cone has increased to 80 %. The status of the plant is ; | Good operating condition | Alkaline condition | Excess solids should be removed from the plant | The aeration tank is being over - aerated |
| Question - 2 of 10 | a | b | c | d |
| There are two definite indications that this action was required. One is ; | The results of the "settleability of activated sludge test" | The results of the pH test | The height of the sludge blanket in the settling tank | The dissolved oxygen level in the aeration tank |
| Question - 3 of 10 | a | b | c | d |
| The other indication is ; | The results of the pH test | The height of the sludge blanket in the settling tank | The dissolved oxygen level in the aeration tank | The color and odor of the liquid in the aeration tank |
| Question - 4 of 10 | a | b | c | d |
| When should excess sludge be removed ? | Wasting sludge should be conducted only when the wind direction is such that it will blow away any offensive odor | Wasting sludge can be carried out at any times | Wasting sludge should be conducted only at night | Wasting sludge can be carried out at any time there are no excessively high flows to the treatment plant |
| Question - 5 of 10 | a | b | c | d |
| Before wasting sludge, which of the following actions should be performed ? | Shut off the air supply to the sludge storage tank air diffusers at least 24 hours prior to discharging excess solids | Check that the air supply to sludge storage tank is set at maximum | There is no action required | Remove sludge from the storage tank for final disposal |
| Question - 6 of 10 | a | b | c | d |
| The next action would be ; | Check that the air supply to the aeration tank is set at maximum | Shut off the air supply to the aeration tank 1 or 2 hours prior to wasting sludge to allow solids to settle | There is no action required | Remove sludge from the storage tank for final disposal |
| Question - 7 of 10 | a | b | c | d |
| The next action prior to wasting sludge should be ; | Perform a "settleability of activated sludge test" on a sample of supernatant taken from the aeration tank | Open the supernatant overflow valve and check to insure that the supernatant from the sludge storage tank is clear | Perform a pH test on a sample of the supernatant | There is no action required |
| Question - 8 of 10 | a | b | c | d |
| After wasting sludge you should ; | Take all actions required to restore plant to normal operation | Action (a) and leave the supernatant return line from the storage tank open for 2 hours | Action (a) and increase aeration tank air supply to maximum for 24 hours | Action (a) and reduce aeration tank air supply to minimum for 24 hours |
| Question - 9 of 10 | a | b | c | d |
| And after the air blowers have been running for 30 minutes you then ; | Perform dissolved oxygen test on sample of liquid from the aeration tank | Perform pH test on sample of liquid from the settling tank | Perform "settleability of activated sludge test" on sample of liquid from the aeration tank | No other action is required |
| Question - 10 of 10 | a | b | c | d |
| Why should you do this test ? | To get info about pH of the process | To get info about DO level of the process | To get info about MLSS concentration | To get info about wasted sludge |
