Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
97 Cards in this Set
- Front
- Back
What is the most common reason for a wastewater to contain intermittent large amounts of sand, gravel, and grit?
|
storm events
|
|
Combined wastewater is defined as:
|
sanitary wastewater and stormwater runoff
|
|
In general, the solids content in wastewater is about:
|
0.1%
|
|
In general, what is the percentage of suspended solids in the amount of total solids is about:
|
30%
|
|
Generally, the percentage of dissolved solids in the amount of total solids is about:
|
70%
|
|
Which type of organisms would most probably be associated with poor treatment or young biomass:
|
amoebas
|
|
Which type of organisms would most probably be associated with very clear plant effluent, low biochemical oxygen demand (BOD), and low amounts of suspended solids?
|
stalked ciliates
|
|
Aerobic bacteria will reproduce and live in an environment that contains only:
|
oxygen
|
|
Anaerobic bacteria will produce and live only in an environment that completely lacks:
|
free or dissolved oxygen (DO)
|
|
The biochemical oxygen demand (BOD) test usually has a specific time of:
|
5 days
|
|
An Imhoff cone measures
|
volume of settleable solids
|
|
Septic conditions are caused by:
|
anaerobic bacteria
|
|
Scum is usually removed in the ___ treatment stage.
|
primary
|
|
When domestic wastewater enters natural waters, what species deplete most of the oxygen?
|
aerobic bacteria
|
|
Once the oxygen is depleted in a naturaly body of water, which organisms take over?
|
anaerobic bacteria
|
|
The major gas produced by anaerobic decomposition is
|
methane
|
|
Another name for primary treatment is:
|
sedimentation
|
|
Digester gas is ___ when mixed with air in the proper proportions.
|
extremely explosive
|
|
A pond that is used to treat raw wastewater is called:
|
a waste stabilization pond
|
|
A pond that has an aerobic top layer and an anaerobic bottom layer is called:
|
a faculative pond
|
|
What is the angle of the bars on a manually cleaned bar screen?
|
30 degrees
|
|
What is the angle of the bars on a mechanically cleaned bar screen?
|
45 to 60 degrees
|
|
what is the ideal wastewater velocity in feet per second through screen channel?
|
1.5ft/sec
|
|
What is the ideal wastewater velocity in ft/s for grit removal in a grit chamber?
|
1 ft/sec
|
|
What is the water content of screened material?
|
80%
|
|
What is the wastewater velocity range in ft/sec for grit removal in a grit chamber?
|
0,7 to 1.4 ft/sec
|
|
Which on of the following chemicals gives water its greatest capacity to neutralize acids?
|
hydroxide
|
|
The bar rack is used:
|
when the bar screen is out of service
|
|
What is the average detention time of wastewater in a primary clarifier?
|
2hr
|
|
Which one of the following gases is irritating to the eyes?
|
chlorine
|
|
Activated sludge clarifiers accept material to be settled from:
|
an aeration tank
|
|
According to Clean Water Act, secondary treatment is defined as a wastewater plant producing an effluent that has no more than ___ total suspended solids and no more that ___ BOD5.
|
30mg/L, 30mg/L
|
|
The color of the biofilm on a rotating biological contactor would appear ___ under normal operating conditions.
|
gray
|
|
A primary effluent and returned activated sludge mixture is called:
|
waste activated sludge
|
|
The mixture of organisms and solids in water that is removed from the settling tank is called:
|
mixed liquor
|
|
Under normal operating conditions, what color is the activated sludge?
|
dark chocolate brown
|
|
What tests could an operator use to make process changes immediately if a problem develops?
|
chemical oxygen demand (COD) test
|
|
The main workers in the activated sludge process are:
|
bacteria
|
|
A yellow gas flame from a digester's waste gas burner may indicate a poor quality gas with a:
|
high CO2 content
|
|
Ponds used in series after primary wastewater treatment are sometimes called:
|
oxidation ponds
|
|
The most common type of pond is:
|
foculative pond
|
|
Which one of the following nuisance organisms is controlled simply by the water surface being disturbed by wind or currents?
|
mosquitoes
|
|
When is the dissolved oxygen in a waste pond the lowest?
|
sunrise
|
|
What would be most likely solution, if the influent to a wastewater treatment plant had an H2S odor?
|
add treatment chemicals
|
|
What is the main reason why wastewater treatment plants remove phosphorus from their effluent before discharging to a lake or river?
|
to reduce the growth of algae
|
|
What is the color of liquid chlorine?
|
amber
|
|
How many times heavier than air is chlorine gas?
|
2.5 times
|
|
Free available chlorine consists of:
|
dissolved chlorine gas, hypochlorous acid, and hypochlorite ion
|
|
The fusible plug on a chlorine cylinder will start to melt at approximately:
|
160F
|
|
This solids treatment method usually has 20 days of retention time:
|
aerobic digestion
|
|
The solids treatment method processes solids in a sealed unit:
|
anaerobic digestion
|
|
This solids treatment method produces methane gas that can be used in other plant processes:
|
anaerobic digestion
|
|
this solids treatment method cures the final product and then it may be applied to farmlands:
|
composting
|
|
This solids treatment method uses evaporation but also requires a great deal of labor:
|
sand drying beds
|
|
This solids treatment method uses a partially submerged rotating drum:
|
vacuum filter
|
|
These solid treatment methods use a coagulant polymer and pressure:
|
belt filter and plate
|
|
Tests such as pH, temp, and dissolved oxygen should always be performed within ___ after collection.
|
15min
|
|
When calibrating a pH meter, the buffers used should bracket the expected pH and:
|
be at least 2 pH units apart
|
|
A test method for determining dissolved oxygen is the:
|
azide modification of the Winkler titration method
|
|
How long can a dissolved oxygen sample wait for analysis using the modified Winkler method, if it is preserved with sulfuric acid?
|
8hrs
|
|
BOD5 samples can be preserved by:
|
storing them in fridge above freezing and up to 4C
|
|
The maximum holding time for preserved BOD5 samples is:
|
2 days
|
|
Which one of the following tests is least likely to effectively help an operator control a waste plant process?
|
BOD5
|
|
the maximum holding time for a preserved total suspended solids sample is:
|
7 days
|
|
The state regulatory body must be notified of all unusual or extraordinary discharges by telephone within:
|
24hrs
|
|
The state regulatory body must be notified of for any noncompliance that could adversely affect that states waters or that could endanger public health within:
|
24hrs
|
|
Electomotive force (emf) is also known as:
|
voltage
|
|
Electron flow is measured in:
|
amps
|
|
What type of fuses would most likely be used to protect a meter?
|
dual element fuses
|
|
What class of fire involves electrical equipment?
|
Class C
|
|
When a permit is required to enter a confined space, who may sign the permit?
|
entry supervisor
|
|
Which one of the following is a measure of a materials opposition to the flow of electric current?
|
ohms
|
|
What class of fire involves oil and grease?
|
Class B
|
|
Why is it essential to ventilate a valve vault before entry?
|
remove dangerous gases
|
|
The primary purpose of check valves is to prevent:
|
water from flowing in two directions
|
|
Which one of the following infectious diseases is not transmitted by wastewater?
|
the acquired immune deficiency syndrome virus (AIDS)
|
|
Which one of the following gases is least likely to collect in a belowground vault?
|
carbon monoxide
|
|
When working in a manhole, your vehicle, whenever possible; should be placed:
|
between the manhole and oncoming traffic
|
|
OSHA requires that adequate protection, such as shoring, be placed in any trench that is:
|
5ft greater in depth
|
|
How far back from the opening of a trench should soil excavated from that trench be placed?
|
2ft at least
|
|
In a trench, ladders are required every:
|
25ft
|
|
How many ladders are required to be in a 5ft deep trench when six people are working down in the trench?
|
six ladders
|
|
Which is not an essential ingredient for all ordinary fires?
a. ignition source b. fuel c. heat d. oxygen |
a. ignition source
|
|
If some clothes are on fire, what class of fire is it?
|
Class A
|
|
If some magnesium is on fire, what class of fire is it?
|
Class D
|
|
What is the minimum number of people that should be on site working at a confined space site, where one of them in entering a manhole?
|
3
|
|
What type of fire extinguishers should be in pump stations
|
A-B-C chemical type
|
|
What piece of laboratory glassware is primarily used to mix chemicals and measure approximate volumes?
|
beaker
|
|
The electric potential between two points is measured in:
|
volts
|
|
What is the most common use today for a positive displacement pump?
|
chemical feed pump
|
|
Which laboratory glassware will give the most accurate measurements of liquids?
|
burettes
|
|
Which laboratory glassware is used for measuring volumes?
|
graduated cylinders
|
|
People working in and around wastewater must be immunized for:
|
tetanus
|
|
Which one of the following laboratory tests has a zero holding time?
|
chlorine residual
|
|
Water is used as a standard becuase it has unique properties and is readily available in its pure state. Which standard is used?
|
kilogram
|
|
What acids are formed when water reacts with nonmetal oxides?
|
acid anhydrides
|
|
Which one of the following is not a hydrate?
|
sodium nitrate
|