Chapter 3 WW
What is a sanitary sewer?
A. a pipe or conduit intended to carry wastewater or waterborne wastes from homes, businesses, and industries.
B. A separate pipe, conduit, or open channel that carries runoff from storms, surface drainage, and street wash.
C. A sewer designed to carry both sanitary wastewater and stormwater or surface water runoff.
D. the seepage of groundwater into a sewer system including service connections .
What is (A)
A pipe or conduit intended to carry wastewater or waterborne wastes from homes, businesses, and industries to the treatment works.
What happens when the car surface water of the primary tank flows over the effluent weir at a high velocity?
A. insufficient food BOD flows into the aeration tank
B. particles settling to the bottom or those already on the bottom may be picked up and carried from the tank
C. re-aeration occurs and reduces the bod
D. the tank empties too quickly
What is (B)
Particles settling to the bottom or those already on the bottom may be picked up and carried from the tank.
The flow velocity in a grit chamber or grit channel is reduced to how many feet per second?
A. 2 fps
B. 1 fps
C. 0.5 fps
D. 3 fps
What is (B)
1 fps
to settle out heavy inorganic material and grit.
A process where organisms with the aid of chlorophyll convert carbon dioxide and inorganic substances into oxygen using sunlight for energy.
A. Endogenous Respiration
B. Photosynthesis
c. Wet Oxidation
D. Anaerobic Digestion
What is (B)
Photosynthesis
Effluents from most wastewater plants are discharged into receiving waters. Some is made into reclaimed water and some is used for land application.
A. True
B. False
What is (A)
True
When are pump (lift stations) stations normally installed?
A. when low areas of land must be sewered or where pipe depth under the ground surface becomes excessive.
B. When sewers need a break to allow for maintenance activities.
C. When the landowners want a structure to blend in with the landscape
D. When wastewater must be treated before it reaches the treatment plant.
What is (A)
When low areas of land must be sewered or where pipe depth under the ground surface becomes excessive.
What are the two major types of bacteria present in a digester?
A. acid formers and gas formers
B. aerobic and anaerobic
C. fecal and e.coli
D. methane and sulfide
What is (A)
Acid formers and gas formers
Flow velocity of the primary sedimentation tank is reduced to _____ fps to allow settleable solids to fall to the bottom of the tank and lighter material to float to the water surface.
A. 0.03 fps
B. 1 fps
C. 2 fps
D. 0.5 fps
What is (A)
0.03 fps
Two types of gas produced in a anaerobic digester are:
A. Hydrogen Sulfide and Chlorine
B. Methane and Carbon Monoxide
C. Hydrogen Sulfide and Carbon Dioxide
D. Carbon Dioxide and Methane
What is (D)
Carbon Dioxide and Methane
A secondary clarifier is needed after a trickling filter or RBC or aeration tank to allow organisms in treated wastewater to be removed by settling?
A. True
B. False
What is (A)
True
What is the purpose of pre-aeration?
A. to freshen the wastewater and to help remove oils and greases
B. to measure and record flows
C. to remove settleable and floatable materials
D. To remove suspended and dissolved solids
What is (A)
to freshen the wastewater and to help remove oils and greases
The time required to fill a tank at a given flow or the theoretical time required for a given flow of wastewater to pass through a tank is know as:
A. Sludge Age
B. Detention Time
C. Mean cell retention time
D. F/M ratio
What is (B)
Detention Time
Primary clarifiers are usually designed to provide ____ to _____ hours of detention time. Secondary clarifiers usually provide slightly more time.
A. 1.5 to 2.0 hours
B. 1.0 to 1.5 hours
C. 0.5 to 1.0 hours
D. 0.3 to 0.5 hours
What is (A)
1.5 to 2.0 hours
In general the longer the detention time, the greater the solids removal. (suspended solids).
In most newer plants sludge digestion takes place in two tanks. The first or primary digester and a secondary tank . What takes place in the first tank?
A. usually heated and mixed, rapid digestion takes place and most of the gas production
B. unheated and mixed rapidly to ensure uniform application for the second tank prior to gas formation
C. Digested sludge and supernatant are allowed to separate, producing a clearer supernatant and better digested sludge results.
What is (A)
The secondary tank is where the digested sludge and supernatant are allowed to separate, producing a clearer supernatant and better digester sludge.
In a secondary clarifier the side wall depth for accumulated sludge blanket should be:
A. 1 ft or less
B. 25% or 1 to 3 feet
C. 4 to 5 feet or 50%
D. 30% or 2 feet
What is (B)
25% of the side wall depth or 1 to 3 feet
Why are most sewer pipes laid at a slope steep enough to maintain a wastewater flow of two feet per second.
A. to ensure straight flow through manholes
B. to prevent grit from settling in the pipes
C. to prevent the release of odors and toxic gases
D. to provide sufficient cover to avoid breaking the pipe
What is (B)
to prevent grit from settling in the pipes
The first stage of a treatment plant is called the preliminary treatment or head works. What happens in this process.
A. screening and grit removal
B. BOD solids removal
C. Odor Control and BOD removal
D. Track unaccounted for influent flow
What is (A)
screening and grit removal
The solids that separate from the water during the primary and secondary settling process is called?
A. Humus
B. sloughings
C. Zoogleal
D. sludge
What is (D)
Sludge
settleable solids separated from liquids during process. Settles to the bottom of the tank and is removed via pump.
In an anaerobic digester the production of ____ indicates that organic material has been eaten by the bacteria.
A. Gas
B. Fermenting organisms
C. Facultative organisms
D. Supernatant
What is (A)
A sludge is usually considered properly digested when 50 percent of the organic matter has been destroyed and converted to gas. Takes about 30 days.
Why should clarifier weirs be kept level?
A. to help operators measure the clarifier effluent flow
B. to help operators record the efficiency of the clarifier
C. to help prevent short circuiting, which reduces the efficiency of the clarifier
D. to help prevent the growth of algae on the weirs.
What is (C)
to help prevent short circuiting which reduces the efficiency of the clarifier
How is oxygen provided for the organisms living in the biological slime that grows on the RBC media?
A. the atmosphere surrounding the media
B. the blowers for the system
C. the diffusers in the bottom of the tank
D. the return or recirculation flows
What is (A)
the atmosphere surrounding the media
The most common measuring device for measuring flow in a wastewater process is called:
A. Turbidity meter
B. parshall flume
C. dissolved oxygen meter
D. weigh scale
What is (B)
Parshall flume
A narrow place in an open channel that allows the quantity of flow to be determined by measuring the depth of flow.
the layer of organisms on a trickling filter media gets so thick that some of it breaks off (sloughing) and is carried to the filter effluent channel. This material is called?
A. Zoogleal
B. Humus
C. Slough
D. Facultative
What is (B)
Humus
Humus is primarily organic matter and is undesirable in a stream. It is usually removed in the secondary clarifier.
A method of treating or conditioning sludge before the water is removed is called:
A. photosynthesis
B. Anaerobic Digestion
C. Aerobic Digestion
D. Wet Oxidation
What is (D)
Wet Oxidation
Compressed air is blown into the liquid sludge. the air and sludge mixture is fed into a pressure vessel where the organic material is stabilized. The organic material is separated from the vessel effluent by dewatering.
The safety procedure that requires that an energy source be turned off and locked, and that information describing why a system is shut down is displayed on a tag is called what?
What is lock-out/tag-out?