Although carbon dioxide is not classified as a poisonous or explosive gas, a high level
of this gas in a confined space is still a safety concern. (True or False) - ✔️✔️True
In the lubrication of motors, bearings, and other mechanical equipment, a good rule of
thumb is to exceed the manufacturers specifications because the more lubrication the
longer the equipment will last. (True or False) - ✔️✔️False
An operator would expect to find the highest concentration of hydrogen sulfide gas near
the top of a manhole. (True or False) - ✔️✔️False
Aerobic digesters produce more methane gas than anaerobic digesters, but it is all lost
to the atmosphere in the aerobic digester. (True or False) - ✔️✔️False
Coliform bacteria are generally considered to be harmless to humans. (True or False) -
✔️✔️True
In normal practice, a secondary digesters main function is to allow solids to separate
from the liquid portion in the digester. (True or False) - ✔️✔️True
Recirculation as practice in the operation of a biological filter is used to recycle the
zoogleal slime which has sloughed from the media. (True or False) - ✔️✔️True
A sample collected for the BOD test may be preserved for 24 hours by adding 1.0 ml/L
of sulfuric acid and refrigerating at 4 degrees Celsius. (True or False) - ✔️✔️False
Inefficient grit removal would tend to cause an increase in the percent volatile solids in
the raw sludge. (True or False) - ✔️✔️False
In order to make the best use of time, preventative maintenance should be performed
as time permits rather than scheduling each task. (True or False) - ✔️✔️False
Channel type grit chambers should have flow through velocity of at least 2.0 feet per
second. (True or False) - ✔️✔️False
Carbon Monoxide and hydrogen sulfide are both toxic gases at room temperature. (True
or False) - ✔️✔️True
When categorizing anaerobic digesters, the term standard rate and high rate refer to the
reaction of rate values for acid and methane formation. (True or False) - ✔️✔️False
, One purpose of an inlet baffle in a settling tank is to disperse the flow. (True or False) -
✔️✔️True
The frequency of pumping raw sludge from a primary clarifier to an anaerobic digester is
the main factor that determines percent solids in the raw sludge. (True or False) -
✔️✔️True
Organic loading to a wastewater treatment pond is usually expressed as pounds BOD
per acre-feet per day. (True or False) - ✔️✔️False
Good laboratory practices include great care when eating, drinking, and/or smoking
while working in the laboratory. (True or False) - ✔️✔️False
The first operating guideline that begins to change when an anaerobic digester is
starting to become upset is the pH. (True or False) - ✔️✔️False
Chlorine dosage rate equals the chlorine demand minus the chlorine residual. (True or
False) - ✔️✔️False
Turbidity is usually caused by high concentrations of dissolved solids. (True or False) -
✔️✔️True
Nitrate compounds can be a source of combined oxygen when treating an upset pond
system. (True or False) - ✔️✔️True
Normally, one would expect the pH to decrease when one observes an increase in the
D.O. of a typical facultative pond. (True or False) - ✔️✔️False
Dissolved oxygen concentrations of 15 mg/L or greater may be found in a facultative
pond during a late summer afternoon on a sunny day. (True or False) - ✔️✔️True
A 24 hour flow proportioned composite sample of chlorinated effluent should be used for
the coliform MPN test. (True or False) - ✔️✔️False
One of the gases produced in a well operated anaerobic digester is carbon dioxide.
(True or False) - ✔️✔️True
An operator should not enter a manhole with a safety harness on, if there are less than
two people above ground to pull the operator out should anything happen. - ✔️✔️True