In which of the following tests should the
sample be allowed to sit for 30 minutes?
2. Activated sludge
3. Settleable solids
4. Hydrogen ion concentration
4-53. A COD test can be performed in a minimum of
how many hours?
4-54. Which of the following tests should be used as
a control test to help you decide whether to
increase or decrease the rate of sludge return?
4-55. Which of the following tests should be
performed within 30 minutes of taking a
Total suspended solids
2. Mixed liquor suspended solids
3. Chlorine residual
4-56. After a sample is chilled to 4°C, a fecal
coliform test should be performed within how
4-57. Laboratory records can be used for which of
the following reasons?
To locate suitable plant operating controls
To point out future plant requirements
3. To protect the government from lawsuits
Each of the above
4-58. Preventive maintenance should be scheduled
so it can be performed at which of the
During good weather only
During peak loads only
During good weather and low loads
During bad weather and peak loads
4-59. For a wastewater plant that discharges
effluent to a body of water, what type of
permit must be obtained from the EPA or
designated state agency?
4-60. What is the cheapest operating effluent
3. Direct discharge
4-61. What type of effluent discharge requires a
place to store the effluent?
4-62. When effluent containing a toxic substance is
accidentally discharged into receiving water
used downstream as a drinking water supply
for recreation or for livestock watering, the
operator is required to notify which of the
The regulating agency only
2. The water users downstream only
3. The regulating agency and the water users
The plant manager and the regulating
4-63. Recycled wastewater is seldom used for what
type of water supply?