What is the methane content in a properly operation anaerobic digester?
A) 30 to 35% by volume
B) 1 to 2% by volume
C) 65 to 70% by volume
D) 15 to 20% by volume
C) 65 to 70% by volume (v.2 pg 158)
What will the addition of chlorine gas do to the pH of wastewater?
A) Moderately increase pH
B) pH will not be affected
C) Significantly increase the pH
D) Decrease the pH
D) Decrease the pH (v.1 pg 349-350)
What is the purpose of a Parshall flume?
A) measure turbidity
B) measure flowrate
C) measure settling rate
D) measure solids content
B) measure flowrate (v.1 pg 43)
What is the typical removal efficiency of settable solids in a primary clarifier?
A) 95 to 99%
B) 40 to 60%
C) 20 to 50%
D) 10 to 15%
A) 95 to 99% (v.1 pg 129)
Which of the following is true about pumping scum from a primary clarifier?
A) Pumping scum is less problematic during colder weather.
B) Scum rarely leads to plugged pipelines due to its viscous nature.
C) Scum causes more piping problems than other substances pumped at a wastewater treatment plant.
D) Scum causes the least amount of piping problems among all the substances pumped at a wastewater treatment plant.
C) Scum causes more piping problems than other substances pumped at a wastewater treatment plant. (v.2 pg 449)
What might cause thick billows of white sudsy foam in the aeration tank?
A) MLSS is too high
B) Temperature in the aeration tank is too low
C) Old sludge
D) MLSS is too low
D) MLSS is too low (v.2 pg 53,75)
What does the “M” in F/M ratio represent?
A) MLSS in aeration tank
B) The influent BOD loading rate into the aeration tank
C) The mixed liquor volatile suspended solids in the aeration tank
D) The mass of inorganic solids in the aeration tank
C) The mixed liquor volatile suspended solids in the aeration tank (v.2 pg 16)
In general, how will warmer temperature affect the settling rate of solids in a clarifier?
A) Decrease settling rate
B) Increase the settling rate
C) Temperature will not affect the settling rate
D) Worsen the settling rate
B) Increase the settling rate (v.1 pg 134)
What could happen if the digester gas is mixed with air (85 to 95% by volume)?
A) Cause an explosion
B) Improve efficiency of digestion
C) The bacteria will become aerobic and increase VSR
D) The digester becomes safer to operate due to less toxic gas in the system
A) Cause an explosion (v.2 pg 158)
How will algae impact the chlorine demand in the pond effluent?
A) Slightly decreases chlorine demand
B) Does not affect chlorine demand
C) Significantly decreases chlorine demand
D) Increases chlorine demand
D) Increases chlorine demand
Which of the following is true about positive displacement pumps?
A) It is a type of centrifugal pump
B) Suction valve should be closed when the pump is started
C) It must never be started with the discharge valve closed
D) Adds head to liquid using several impellers
C) It must never be started with the discharge valve closed (v.2 pg 435)
What is true about the F/M ratio?
A) MLVSS data in not required to determine the F/M ration
B) Volume of the secondary clarifier is not needed to determine the F/M ratio
C) The amount of COD or BOD entering the aeration tank does not have to be known to calculate the F/M ratio.
D) The amount of organisms in the aeration tank is not needed to calculate the F/M ratio
B) Volume of the secondary clarifier is not needed to determine the F/M ratio (v.2 pg 58)
Which of the following is one of the basic rules of laboratory work?
A) Do not leave keys in equipment or vehicles at any time
B) Patrol the facilities frequently, and look for suspicious activity or behavior
C) never pipet hazardous material with your mouth, even if the pipet has be sterilized
D) Lock out and tag out relevant mechanical and electrical equipment before starting any maintenance activity.
C) never pipet hazardous material with your mouth, even if the pipet has be sterilized (v.2 pg 493)
What is the recirculation ratio for a trickling filter?
A) Q_r/Q
B) Q/Q_r
C) Q/Q_r+Q
D) Q_r+Q/Q
A) Q_r/Q
Which of the following is true about COD and BOD?
A) They are direct measurements of organic content in the influent
B) They measure the inorganic content of the influent
C) They represent the amount of filamentous bacteria in the influent
D) They are indirect measurements of the organic content in the influent
D) They are indirect measurements of the organic content in the influent
What is the purpose of the grit channel?
A) Remove dissolved and non-settleable organics
B) Remove heavy inorganic wastes
C) To allow activated sludge to settle
D) Remove substances that float and readily settle from the wastewater as part of primary treatment
B) Remove heavy inorganic wastes (v.1 pg 84)
Which of the following is true about the extended aeration process?
A) Bugs get more food
B) Wasting is not necessary
C) It does not produce as much waste sludge as the other processes
D) It is very different from the conventional activated sludge process
C) It does not produce as much waste sludge as the other processes (v.1 pg 257)
What is the correct formula for solids in raw wastewater?
A) Non-volatile solids + Suspended solids= Total solids in the influent
B) Dissolved solids + Settable solids= Total suspended solids
C) Colloids + Dissolved solids = Total suspended solids
D) Non-settleable solids + Settable solids= Total suspended solids.
D) Non-settleable solids + Settable solids= Total suspended solids (v.1 pg 22)
What is the “freeboard” in a waste stabilization pond?
A) Operational depth of the pond
B) Wooden inlet and outlet structures
C) Wooden baffles
D) Vertical distance from normal water surface to the top of the levee
D) Vertical distance from normal water surface to the top of the levee (v.1 pg 519)
What is one of the requirements for a BOD test?
A) The BOD bottle should be completely filled to the top
B) The BOD bottles must be 100 ml in size
C) Samples should be incubated at 30 degrees Celsius
D) Stoppers should not be installed on the bottles to ensure proper air flow to the samples
A) The BOD bottle should be completely filled to the top (v.2 pg 574)
What should be scheduled every 3 months for a flamer arrester in an anaerobic digester?
A) Replacement
B) Maintenance
C) Flow Test
D) Temperature Test
C) Flow Test (v.2 pg 162)
What is common practice in an activated sludge process?
A) Waste all activated sludge
B) Sludge age of 14 days for conventional system
C) Recirculate activated sludge (RAS)
D) Limiting DO to increase the mircoorganism population
C) Recirculate activated sludge (RAS) (v.2 pg 20,21)
Prior to entering a permit required confined space, what should you verify?
A) a standby person should be at the entrance to the confined space. An additional person is not required
B) A standby person should be within 30 feet of the confined space.
C) A standby person should be within 50 feet of the confined space.
D) A standby person should be located outside the entrance to the confined space, while another person should be within sight or call of the standby person.
D) A standby person should be located outside the entrance to the confined space, while another person should be within sight or call of the standby person. (v.2 pg 270)
What is a common way to determine the organic strength of wastes in the influent?
A) Test for the biochemical oxygen demand
B) Test for the biological oxygen demand
C) Test for the volatile solids reduction
D) Test for the carbon and hydrogen concentrations
A) Test for the biochemical oxygen demand (v.1 pg 505)
What should you do if you are mildly exposed to chlorine gas?
A) Breathe heavily to inhale clean air
B) Cough to release chlorine from lungs
C) Immediately evacuate the contaminated area, remain calm, keep warm, breathe lightly, and avoid coughing
D) Keep your body as cool as possible
C) Immediately evacuate the contaminated area, remain calm, keep warm, breathe lightly, and avoid coughing (v.1 pg 377)
What are the main sources of domestic sewage in the collection system?
A) Canals
B) Surface flow
C) Ocean outfall
D) Households and commercial establishments
D) Households and commercial establishments (v.1 pg 33)
Why is it important to maintain a horizontal weir in a clarifier?
A) Prevent sludge bulking
B) Prevent short circuiting
C) Prevent gasification
D) Prevent excessive slime growth
B) Prevent short circuiting (v.1 pg 131)
What are mostly removed in the grit channel?
A) Biomass
B) Organics
C) Dissolved solids
D) Sand, eggshells, cinders, and heavier particulate matter
D) Sand, eggshells, cinders, and heavier particulate matter (v.1 pg 84)
How often should an anaerobic digester be fed?
A) Several times a day
B) Once a day
C) Twice a week
D) Five times per week
A) Several times a day (v.2 pg 185)
What is the health effect of carbon dioxide?
A) Vomiting
B) Migraine
C) Can lead to asphyxiation
D) Rapid heart beat
C) Can lead to asphyxiation (v.2 pg 268)
Which of the following enters the headworks of a treatment plant?
A) Effluent
B) Supernatant
C) WAS
D) Influent
D) Influent (v.1 pg 33)
Which gas diminishes your sense of smell?
A) Hydrogen
B) Hydrogen Sulfide
C) Nitrogen
D) Ethane
B) Hydrogen Sulfide (H_2S) (v.2 pg 268)
What type of microorganisms can use nitrate as a source of oxygen?
A) Aerobic bacteria
B) Anaerobic bacteria
C) Facultative bacteria
D) Zoogleal
C) Facultative bacteria (v.1 pg 254)
What is the equivalent of 1 mg/L
A) 1 ppb
B) 10 ppm
C) 10 ppb
D) 1 ppm
D) 1 ppm (v.1 pg 468)
Select the most accurate statement about extended aeration.
A) The bugs are retained in the aeration tank much shorter than the conventional activated sludge system.
B) Extended aeration produces the most waste sludge compared to other sludge processes
C) An oxidation ditch is usually operated in extended aeration mode, and is used for small flows
D) Extended aeration is the least common type of package plant treatment process
C) An oxidation ditch is usually operated in extended aeration mode, and is used for small flows (v.1 pg 269)
What is equivalent to organic solids?
A) Volatile Solids
B) Fixed Solids
C) Suspended Solids
D) Colloids
A) Volatile Solids (v.1 pg 546)
What should be done if a large amount of organic matter is found in the grit channel?
A) Decrease the velocity of the wastewater
B) Inject sodium hydroxide at the headworks
C) Raise the pH
D) Increase the velocity of the wastewater
D) Increase the velocity of the wastewater (v.1 pg 87)
Which flowrate should you use to calculate the hydraulic loading to a trickling filter?
A) Plant inflow
B) Plant inflow minus recirculated flow
C) Plant inflow plus recirculated flow
D) Recirculated flow
C) Plant inflow plus recirculated flow (v.1 pg 199)
What is the difference between the sludge from a primary clarifier and secondary clarifier?
A) Secondary sludge is denser than primary sludge
B) Primary sludge is denser than secondary sludge
C) Specific gravity of secondary sludge is larger than that of a primary sludge
D) Primary sludge has a smaller specific weight than secondary sludge
B) Primary sludge is denser than secondary sludge (v.1 pg 109)
Which process includes a blower?
A) Trickling filter
B) Waste stabilization pond
C) Chlorine contact tank
D) Activated sludge
D) Activated sludge (v.2 pg 28)
How does an activated sludge system remove waste from wastewater?
A) Physical Treatment
B) Chemical Treatment
C) Biological Treatment
D) Radiological Treatment
C) Biological Treatment (v.2 pg 16)
Which of the following best describes pre-chlorination?
A) Mainly used for disinfection and requires a large amount of chlorine residual in the wastewater at the chlorine contact chamber.
B) Addition of chlorine to wastewater a the entrance to the plant, and used for odor control, BOD reduction, grease removal, and aid sedimentation
C) Injection on a well-clarified effluent
D) Describes a type of chlorination to address sludge bulking
B) Addition of chlorine to wastewater a the entrance to the plant, and used for odor control, BOD reduction, grease removal, and aid sedimentation (v.1 pg 354)
When would you expect reduced algae population and less oxygen released into a pond?
A) Fall and winter, when the weather is cool and sunlight is reduced
B) Summer, when there is abundant sunlight
C) Spring, when the weather transitions from cool to warm
D) When photosynthesis is very effective and at its peak
A) Fall and winter, when the weather is cool and sunlight is reduced (v.1 pg 309)
What is the first step of the lockout/tagout procedure?
A) Shut down the equipment if it is operating
B) Operate the energy isolating device so that the equipment is isolated form its energy source
C) Lockout the equipment with assigned lock or tag
D) Notify all affected employees that a lockout or tagged system is going to be used and the reason why.
D) Notify all affected employees that a lockout or tagged system is going to be used and the reason why (v.2 pg 274)
What type of process is the activated sludge system?
A) Anaerobic
B) Anoxic
C) Aerobic
D) Ionic
C) Aerobic (v.1 pg 46)
What will happen if too much raw sludge is added to the digester?
A) pH will increase due to the increase in sodium hydroxide
B) Acid fermenters will predominate and lower the pH
C) pH will not be affected
D) Methane fermenters will thrive
B) Acid fermenters will predominate and lower the pH (v.2 pg 184)
What might cause sludge to rise in a clarifier?
A) Gasification from aging sludge
B) pH is too high
C) Sludge withdrawal rate is too high
D) Photosynthesis
A) Gasification from aging sludge (v.1 pg 129)
What happens when carbon dioxide is removed from a pond?
A) Decreased pH
B) pH is not affected
C) Increased pH
D) Sudden increase in H_2S
C) Increased pH (v.1 pg 299)
How much dissolved oxygen should be in a conventional activated sludge system if good effluent is being produced?
A) 6 to 8 mg/l
B) 0.5 to 1 mg/l
C) 4 to 6 mg/l
D) 2 to 4 mg/l
D) 2 to 4 mg/l (v.2 pg 53)
What is the typical concentration of mixed liquor suspended solids in a conventional activated sludge process?
A) 50 to 1,000 mg/l
B) 1,000 to 4,500 mg/l
C) 4,500 to 5,500 mg/l
D) 5,500 to 6500 mg/l
B) 1,000 to 4,500 mg/l (v.2 pg 54)
The temperature of the plant influent is
A) Slightly warmer than tap water
B) Slightly colder than tap water
C) Much cooler than tap water
D) Much warmer than tap water
A) Slightly warmer than tap water
The purpose of disinfection is to
A) kill all microorganisms in the wastewater
B) Stabilize the pH
C) Destruction or inactivation of pathogenic bacteria
D) Oxidize the minerals in the effluent
C) Destruction or inactivation of pathogenic bacteria (v.1 pg 353)
What must you do before entering a room with harmful concentration of chlorine gas in the air?
A) Read the O&M manual
B) Wear self-contained breathing apparatus (SCBA)
C) Prepare the fire extinguishers
D) Cover your mouth and spray aqueous ammonia in the room.
B) Wear self-contained breathing apparatus (SCBA) (v.1 pg 375)
What does black sludge at the bottom of a secondary clarifier located downstream of a trickling filter signify?
A) Pumping rate is excessive
B) Pumping duration is too long
C) Detention time is too short
D) Sludge has stayed in the secondary clarifier too long
D) Sludge has stayed in the secondary clarifier too long (v.1 pg 138)
If the lab results show that the plant influent sample has a COD of 100 mg/l and the BOD of 300 mg/l, which of the following is most likely true?
A) Lab results appear incorrect
B) Carbon concentration is very high
C) Organic content is unusually high
D) COD seems excessive
A) Lab results appear incorrect (v.2 pg 541)
If a primary clarifier is placed out of service, then how should a plant with at least two trickling filters operate the system?
A) Operate the filters in parallel
B) Divert the influent to several trickling filters
C) Operate the filters in series
D) Maintain existing operation without changing filter arrangement
C) Operate the filters in series (v.1 pg 191)
What is the main reason for preventing a direct connection between potable water pipe and a stuffing box (packings) of a wastewater pump?
A) Wears out the glands quicker
B) Glands should not be wet
C) Potable water will rapidly destroy the stuffing box
D) Cross Connection
D) Cross Connection (v.2 pg 414)
Which of the following is true about algae in a pond?
A) During the daytime, the algae will release carbon dioxide
B) During the daytime, the algae will release oxygen for the aerobic bacteria
C) Algae uses sunlight to produce hydrogen sulfide
D) Photosynthesis helps algae create carbon monoxide
B) During the daytime, the algae will release oxygen for the aerobic bacteria (v.1 pg 299)
Which of the following is not true about hydrogen sulfide?
A) Hydrogen sulfide is flammable
B) Hydrogen sulfide is explosive under certain conditions
C) Hydrogen sulfide is lighter than air
D) Hydrogen sulfide is toxic
C) Hydrogen sulfide is lighter than air (v.2 pg 268,505)
What type of treatment if primarily used to thicken sludge instead of dewater the sludge?
A) DAF
B) Sludge drying bed
C) Centrifuge
D) Vacuum filters
A) DAF (v.2 pg 219-227)
Why should sludge at the bottom of a clarifier be removed in a timely manner?
A) To improve the performance of the grit channel
B) To maintain a consistent volume of sludge in the drying bed
C) To minimize the formation of Chloramines
D) To prevent sludge gasification, which causes the sludge to float
D) To prevent sludge gasification, which causes the sludge to float (v.1 pg 130)
What is the purpose of sludge digestion?
A) Convert primary and secondary sludge to mostly hydrogen sulfide
B) Increase efficiency of the DAF
C) Reduce the volume of the sludge and stabilize the solids
D) increase solids volume
C) Reduce the volume of the sludge and stabilize the solids (v.2 pg 148)
Which of the following is true about trickling filters?
A) It is mostly an anaerobic process
B) The three main parts of a trickling filter are media, distribution system, and underdrain
C) In computing BOD loading, it is standard practice to include the BOD of the re-circulated effluent
D) Filter ponding is usually due to inadequate organic loading
B) The three main parts of a trickling filter are media, distribution system, and underdrain (v.1 pg 169)
Which of the following could cause foaming in an anaerobic digester?
A) Temperature is kept constant
B) Feeding sludge at a regular, short interval
C) Digester is well-mixed
D) Organic overload
D) Organic overload (v.2 pg 187,207)
Which of the following parameters should be monitored several times a week in a pond?
A) TDS
B) MLSS
C) Dissolved oxygen, temperature, and pH
D) MLVSS
C) Dissolved oxygen, temperature, and pH (v.1 pg 315)
Which is true about the temperature in an anaerobic digester?
A) Temperature in a digester should not be changed by more than 1 degree Fahrenheit per day.
B) Temperature must be changed significantly according to the sludge loading rate.
C) Temperature at the bottom should be higher than at the top of the digester.
D) Mesophilic digestion required a temperature between 105 to 108 degrees Fahrenheit.
A) Temperature in a digester should not be changed by more than 1 degree Fahrenheit per day (v.2 pg 191)
The effectiveness of disinfection is determined by:
A) The Chlorine residual concentration
B) The Chlorine demand
C) The Chloramine concentration in the effluent
D) The coliform concentration in the effluent
D) The coliform concentration in the effluent (v.1 pg 353)
An increase in the acid/alkalinity ratio for an anaerobic digester means
A) The digester is in an ideal condition
B) The carbon dioxide content is decreasing
C) Acid concentration is increasing or alkalinity is decreasing
D) pH of the sludge in the digester is increasing
C) Acid concentration is increasing or alkalinity is decreasing (v.2 pg 191)
Which of the following will not cause short circuiting in a clarifier?
A) Uneven weir settings
B) Flow line of launder is low
C) Damaged or missing inlet baffles
D) Velocity of wastewater is greater in some sections than in others
B) Flow line of launder is low (v.1 pg 125,135)
A grab sample is most suited for these constituents
A) BOD
B) TSS
C) Suspended Solids Concentration
D) Residual Chlorine
D) Residual Chlorine (v.2 pg 499)
The organic loading to a trickling filter is expressed as
A) lbs BOD/day/1000 cuft
B) lbs BOD/day/1000 sqft
C) lbs BOD/day/sqft
D) lbs BOD/1000 gallon
A) lbs BOD/day/1000 cuft (v.1 pg 199)
How often should the sludge at the bottom of a clarifier be pumped?
A) Once a week
B) Bi-weekly
C) Frequently throughout the day
D) Once every three days
C) Frequently throughout the day (v.1 pg 130)
Which of the following will not affect the settling characteristics in a clarifier?
A) Temperature
B) Short Circuit
C) Detention Time
D) Depth of launder
D) Depth of launder (v.1 pg 134-135)
The best way to evaluate the effluent TSS concentration from a plant is to
A) Check the grab sample at peak flow
B) Check the composite sample of TSS
C) Check the grab sample at low flow
D) Check the grab sample during average flow
B) Check the composite sample of TSS (v.1 pg 128)
Which of the following is not associated with an aeration tank?
A) RAS
B) WAS
C) RBC
D) MCRT
C) RBC (v.2 pg 56,59)
What creates hydrogen sulfide?
A) Excessive aeration
B) Surface active agents
C) Organic matter under aerobic condition
D) Decomposing organic matter under anaerobic condition
D) Decomposing organic matter under anaerobic condition (v.2 pg 299)
A pond with a detention time of less than three days will perform similar to
A) Sedimentation tank
B) Aeration tank
C) Trickling Filter
D) RBC
A) Sedimentation tank (v.1 pg 299)
Which type of Bacteria is used for a Trickling Filter?
A) Anaerobic bacteria
B) Anoxic bacteria
C) Aerobic bacteria
D) Facultative bacteria
C) Aerobic bacteria (v.1 pg 46)
Which of the following is not associated with a trickling filter?
A) Media
B) Filamentous bacteria
C) Zoogleal Film
D) Recirculation
B) Filamentous bacteria (v.1 pg 169)
What is an MCRT?
A) A calculation that indicates the tendency of activated sludge solids to thicken
B) A measure of food provided to bacteria in an aeration tank.
C) The amount of volatile suspended solids in the mixed liquor of an aeration tank
D) An expression of the average time a microorganism will spend in an activated sludge process.
D) An expression of the average time a microorganism will spend in an activated sludge process. (v.2 pg 59)
What is the typical BOD removal efficiency in a primary clarifier?
A) 10 to 15%
B) 40 to 60%
C) 20 to 50%
D) 95 to 99%
C) 20 to 50% (v.1 pg 129)
What does the “F” in F/M ratio represent?
A) The microorganism population in the aeration tank
B) The amount of filamentous bacteria in the activated sludge process
C) The MLVSS in the aeration tank
D) The food for the microorganisms flowing into the aeration tank, in lbs/day
D) The food for the microorganisms flowing into the aeration tank, in lbs/day (v.2 pg 58)
Which of the following describes the appearance of healthy activated sludge?
A) Thick, greasy, dark tan foam
B) Brown with a moderate amount of crisp, white foam
C) Clear liquid with clear foam
D) Gray liquid with no foam
B) Brown with a moderate amount of crisp, white foam
What is used to control filamentous organisms?
A) Polymer
B) Sulfur Dioxide
C) Coagulant
D) Chlorine
D) Chlorine (v.1 pg 399)
What are commonly used to control chlorine feed rate for disinfection?
A) BOD and MLVSS
B) pH and temperature
C) Flow and chlorine residual
D) DO and TSS
C) Flow and chlorine residual (v.1 pg 356)
Which toxic gas is commonly found in septic wastewater and smells like rotten eggs?
A) Hydrogen Sulfide
B) Carbon monoxide
C) Hydrogen
D) Carbon Dioxide
A) Hydrogen Sulfide (v.2 pg 299)
What is the permissible exposure limit for chlorine gas vapor during a normal 8 hour workday and a 40 hour work week?
A) 0.1 ppm
B) 0.5 ppm
C) 1 ppm
D) 15 ppm
B) 0.5 ppm (v.2 pg 268)
What is a vulnerability assessment?
A) Assesses the impact of hydrogen sulfide to a concrete structure
B) Analyzes the impact of flow and infiltration problem to the plant hydraulics
C) Estimates the vulnerability of aquatic wildlife to excessive algae growth
D) Contingency planning to determine the vulnerability of the utility during various types of emergencies and identify corrective actions to reduce the risks
D) Contingency planning to determine the vulnerability of the utility during various types of emergencies and identify corrective actions to reduce the risks (v.2 pg 722)
What is the difference between the settling rate of activated sludge and raw sludge?
A) Activated sludge settles slightly faster than raw sludge
B) Activated sludge settles at the same rate as raw sludge
C) Activated sludge settles slower than raw sludge
D) Activated sludge settles much faster than raw sludge
C) Activated sludge settles slower than raw sludge (v.1 pg 109)
What should be mostly found in healthy activated sludge?
A) Tiny flagellates
B) Amoeboids
C) Short Filaments
D) Free swimmers and stalked ciliates
D) Free swimmers and stalked ciliates (v.2 pg 120,124)
One to two percent of the digester gas in an anaerobic consists of
A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases
B) Methane
C) Carbon Dioxide
D) CH_4
A) Hydrogen, Nitrogen, Hydrogen sulfide, and other gases (v.2 pg 158)
What is true during the colder winter months?
A) Modify operations to decrease solids under aeration to provide less microorganisms to treat the BOD
B) Modify operations to increase solids under aeration to provide more microorganisms to treat the BOD
C) Biological activity will increase, which results in more overall sludge production
D) Microorganisms become more active
B) Modify operations to increase solids under aeration to provide more microorganisms to treat the BOD (v.2 pg 71)
What type of sludge would you expect in an aeration tank if the content is dark and has low DO?
A) Sludge that is heavy
B) Chlorinated Sludge
C) Septic Sludge
D) Healthy Sludge
C) Septic Sludge (v.2 pg 75)
What could have happen if the volatile acid/alkalinity ratio starts to increase, and corrective action is not taken immediately?
A) Carbon dioxide content in the digester gas will decrease
B) Carbon monoxide content in the digester gas will fluctuate
C) pH of the digester sludge will increase
D) Carbon dioxide content in the digester gas will increase
D) Carbon dioxide content in the digester gas will increase (v.2 pg 191)
What are screenings?
A) Colloids
B) TDS
C) Pieces of wood, roots, rags, and other large debris
D) COD
C) Pieces of wood, roots, rags, and other large debris (v.1 pg 41)
What happens when there is more food in the influent to the aeration tank?
A) Less oxygen is required in the aeration tank
B) More oxygen is required in the aeration tank
C) Less organism activity takes place
D) Less oxidation takes place
B) More oxygen is required in the aeration tank (v.2 pg 19)
What impact does temperature have on the reaction rate of microorganisms in wastewater?
A) Reaction rate doubles with every 18 degree Fahrenheit increase in temperature until higher temperature inhibits biological activity
B) Reaction rate decreases by 20% with every 10 degree Fahrenheit increase in temperature
C) Reaction rate of microorganism is not impacted by temperature
D) Reaction rate goes to zero
A) Reaction rate doubles with every 18 degree Fahrenheit increase in temperature until higher
What is commonly used to control the odor of hydrogen sulfide?
A) Carbon Dioxide
B) Methane
C) Chlorine
D) Hydrogen
C) Chlorine (v.1 pg 398)
What is used to determine the amount of microorganisms in the aeration tank?
A) Mixed Liquor Suspended Solids (MLSS)
B) Influent TSS
C) BOD
D) Mixed Liquor Volatile Suspended Solids (MLVSS)
D) Mixed Liquor Volatile Suspended Solids (MLVSS) (v.2 pg 58)
What could happen if the sludge line is isolated by closing the valves on each end for several days?
A) It could result in water hammer
B) Cavitation
C) Gas production could increase the internal pressure and cause the line to fail
D) The aerobic condition will cause Zoolgleal mass to grow in large numbers.
C) Gas production could increase the internal pressure and cause the line to fail (v.2 pg 152)
Which is true about chlorine gas?
A) It is 2.5 times lighter than air
B) it is 2.5 times heavier than air
C) It is 1.5 times heavier than air
D) It is 1.5 times lighter than air
B) it is 2.5 times heavier than air (v.1 pg 375)
Which of the following is typically treated by biological processes?
A) Roots and rags
B) Sand and eggshells
C) Cinders
D) Dissolved and non settable organic material
D) Dissolved and non settable organic material (v.1 pg 46)
Which document is a written record that accurately traces the custody of wastewater samples through all phases of a monitoring program?
A) Wastewater Lab Analysis form
B) NEPA
C) Chain of Custody form
D) Diagnostic form
C) Chain of Custody form (v.2 pg 498)
What could cause a sudden drop in pH of the influent?
A) Acidic chemical in the influent
B) A strong base was dumped into the collection system
C) Ammonia from a factory was discharged into the sewer
D) The influent contained sodium hydroxide
A) Acidic chemical in the influent (v.2 pg 579)
What is the recommended daily maintenance activity for a clarifier?
A) Dewater the clarifier by draining the wastewater
B) Repaint metal surfaces that have lost their protective coating
C) Hose down walls, floor and equipment inside the clarifiers
D) Inspect chains, sprockets, and flights.
D) Inspect chains, sprockets, and flights (v.1 pg 118)
Which of the following could be the cause of ponding in a trickling filter?
A) Hydraulic loading is too low
B) Clogging of distributor orifices
C) Excessive organic loading
D) Denitrification
C) Excessive organic loading (v.1 pg 192)
What could happen if the dissolved oxygen content in the aeration tank is too low?
A) Pinpoint floc will develop
B) Filamentous organisms could thrive and prevent the sludge sludge floc from settling properly in the secondary clarifier
C) Settling will improve in the secondary clarifier
D) Sludge bulking will be eliminated
B) Filamentous organisms could thrive and prevent the sludge sludge floc from settling properly in the secondary clarifier (v.1 pg 254)
What is the expected BOD removal efficiency in a facultative pond?
A) Mostly between 40 to 50%
B) Mostly between 30 to 40%
C) Mostly between 20 to 30%
D) Mostly between 70 to 80%
D) Mostly between 70 to 80% (v.1 pg 317)
What is a chloramine?
A) Free chlorine
B) A chemical that is formed when chlorine reacts with iron
C) Combined chlorine- a chemical that is formed when chlorine reacts with ammonia
D) A chemical that is formed when chlorine reacts with air.
C) Combined chlorine- a chemical that is formed when chlorine reacts with ammonia (v.1 pg 350)
What is sludge bulking in an activated sludge process?
A) When mixed liquor solids settle slowly and compact to a limited extent
B) When old sludge denitrify and cause sludge to rise as a result of gastrification
C) When sludge form large aggregates and cause sludge to settle quickly
D) When compaction in the secondary clarifier is improved due to chemical injection
A) When mixed liquor solids settle slowly and compact to a limited extent (v.2 pg 71)
What is the most common imbalance in an anaerobic digester?
A) Excess methane formation
B) Excess nitrogen formation
C) Excess acid formation
D) Excess carbon dioxide formation
C) Excess acid formation (v.2 pg 148)
What is the only reliable method of detecting hydrogen sulfide?
A) Sense of smell
B) Atmospheric monitoring
C) Color titration
D) Lab test
B) Atmospheric monitoring (v.2 pg 271)
What is sludge age?
A) An expression of the average time that a microorganism will spend in the activated sludge process, and calculated using total suspended solids removed from the process
B) A measure of food provided to bacteria in an aeration tank
C) The theoretical time required for water to pass through a tank at any given flowrate
D) A rough indicator of the length of time a pound of solids is maintained under aeration
D) A rough indicator of the length of time a pound of solids is maintained under aeration (v.2 pg 519)
What is one of the benefits of a COD test over a BOD test?
A) COD test does not require any chemicals to perform the test
B) COD test will easily predict the effects of an effluent on the DO in receiving waters
C) Shorter test period
D) COD test is capable of measuring the biodegradability of matter
C) Shorter test period (v.2 pg 541)
What is the typical detention time for a primary clarifier?
A) 3 to 4 hours
B) 30 minutes
C) 6 hours
D) 1.5 to 2 hours
D) 1.5 to 2 hours (v.1 pg 43)
If you are testing the pH of a wastewater sample, what is the maximum recommended holding time?
A) 5 days
B) It must be tested immediately
C) 24 hours
D) 36 hours
B) It must be tested immediately (v.2 pg 502)
What could cause short circuiting in a clarifier?
A) Sludge composition
B) Reduction in flowrate
C) Uneven weir settings
D) Broken sludge pump
C) Uneven weir settings (v.1 pg 125)
What could cause the slime growth on a rotating biological contactor to appear black?
A) It could indicate solids or organic overloading
B) High DO in the plant effluent
C) Lack of BOD in the influent to the rotating biological contactor
D) Low hydraulic loading
A) It could indicate solids or organic overloading (v.1 pg 228)
What is an air gap?
A) A distance between blowers in an activated sludge system
B) The vertical distance between the surface of wastewater and the top of basin
C) Backflow prevention
D) Type of aeration equipment
C) Backflow prevention (v.1 pg 503)
Which is true about chlorine demand?
A) Chlorine demand= Chlorine residual + Chlorine dose
B) Chlorine demand= Chlorine does x Chlorine residual
C) Chlorine demand= Chlorine residual – Chlorine dose
D) Chlorine demand= Chlorine dose – Chlorine residual
D) Chlorine demand= Chlorine dose – Chlorine residual (v.1 pg 352)
What is accomplished by the activated sludge process?
A) Anaerobic bacteria use SO_4 to eat incoming volatile solids
B) Remove soluble or finely divided suspended materials
C) Anoxic microorganisms destroy incoming BOD
D) Zoogleal breaks down influent organics
B) Remove soluble or finely divided suspended materials (v.2 pg 16)
What is the carbon dioxide content of a properly functioning anaerobic digester?
A) 65 to 70% by volume
B) 1 to 2% by volume
C) 30 to 35% by volume
D) 40 to 60% by volume
C) 30 to 35% by volume (v.2 pg 158)
Which of the following is a collection of individual samples obtained at regular intervals?
A) Grab
B) Culmination
C) Comprehensive
D) Composite
D) Composite (v.2 pg 499)
What is the most common piece of laboratory equipment, which is used mainly to mix chemicals and measure approximate volumes?
A) Beaker
B) Graduated cylinder
C) Pipet
D) Flask
A) Beaker(v.2 pg 479)
What are colloids?
A) Solids that settle rapidly
B) Dissolved solids
C) Solids found in the grit channel
D) Very small, finely divided solids that remain dispersed in a liquid for a long time
D) Very small, finely divided solids that remain dispersed in a liquid for a long time (v.1 pg 22,144)
What is the most common type of grit collector?
A) Deflectors
B) Weirs
C) Chain driven scrapers called “flights”
D) Parshall flume
C) Chain driven scrapers called “flights” (v.1 pg 87)
What is true about surface loading and detention time?
A) They stay fairly constant throughout the day
B) They are impacted by the influent BOD
C) They are indirectly related to flow
D) They are directly related to flow
D) They are directly related to flow (v.1 pg 118)
What is the slime growth on a trickling filter called?
A) Filamentous bacteria
B) Zoogleal film
C) Stalked ciliate
D) Acid formers
B) Zoogleal film (v.1 pg 169)
What should be done if you observe a small, steady stream of water leakage from the pump packings?
A) tighten the packings until they are water tight
B) Replace the packing
C) Do nothing. The leakage is required to cool and lubricate the dynamic surface
D) Replace the pump
C) Do nothing. The leakage is required to cool and lubricate the dynamic surface (v.2 pg 344)
What should be done if the SVI is high and there is an excess of normal filamentous microorganisms in the activated sludge process?
A) Inject hydrogen peroxide in the secondary effluent
B) Make sure DO levels is very low in the aeration tank
C) Decrease MLSS and sludge age
D) Chlorinate the return activated sludge
D) Chlorinate the return activated sludge (v.2 pg 60)
When is confined space considered oxygen deficient?
A) In atmosphere where oxygen content is less than 19.5% by volume
B) In atmosphere where oxygen content is less than 23.5% by volume
C) In atmosphere where oxygen content is less more than 23.5% by volume
D) In atmosphere where oxygen content is less than 29.5% by volume
A) In atmosphere where oxygen content is less than 19.5% by volume (v.2 pg 267)
Which of the following is not true about chlorine gas?
A) 2.5 times heavier than air
B) Extremely toxic
C) Common chlorine gas concentration at the treatment plants is 12.5%
D) Corrosive in moist atmosphere
C) Common chlorine gas concentration at the treatment plants is 12.5% (v.1 pg 375)
What is a “dead spot” in an activated sludge process?
A) An area in the secondary clarifier with rising sludge
B) An area in the aeration tank that has insufficient mixing
C) An area in the aeration tank that has high concentration of DO
D) An area in the secondary clarifier with may dead viruses
B) An area in the aeration tank that has insufficient mixing
Which of the following is an improper way to control an anaerobic digester?
A) Control the loading rate or food supply
B) Control the volatile acid/alkalinity relationship
C) Control mixing
D) Control the acid formation so that it is larger than the methane formation
D) Control the acid formation so that it is larger than the methane formation (v.2 pg 148)
Which of the following is not true about permitted confined space entry?
A) Wear an approved harness with an attached line
B) If the entry is made through a top opening, use a hoisting device with a harness that suspends a person in an upright position
C) Testing for atmospheric hazards is not required as long as a blower is in use
D) Wear protective clothing when entering a confined space that contains corrosive substances or other substances harmful to the skin
C) Testing for atmospheric hazards is not required as long as a blower is in use (v.2 pg 270)
What is a MSDS?
A) A federal law that is designed to protect the health and safety of workers
B) A condition in which a persons nose is no longer able to detect odor from a chemical
C) A document that contains important information about a chemical, such as safe exposure level, flammability rating, and first aid procedures
D A publication written by the federal government that contains all regulations, including those that affect safety and the environment
C) A document that contains important information about a chemical, such as safe exposure level, flammability rating, and first aid procedures (v.2 pg 728)
How often should grit be removed from the grit channel?
A) Weekly
B) Monthly
C) Bi-weekly
D) Daily
D) Daily (v.1 pg 87)
What is the typical removal efficiency from bacteria in a primary clarifier?
A) 0-5%
B) 25-75%
C) 5-10%
D) 10-20%
B) 25-75% (v.1 pg 129)
What problem could most likely cause a centrifugal pump to discharge at a reduced rate?
A) Damaged impeller
B) Slight water leak at the packings
C) Pumping against less resistance
D) Seal water is dripping slowly
A) Damaged impeller (v.1 pg 182)
What is the two categories of coliform bacteria?
A) Lactose and lauryl tryptose
B) Primary and secondary
C) Free swimming and stalked
D) Total and Fecal
D) Total and Fecal (v.2 pg 552)
Which of the following is true about the extended aeration process?
A) Wasting is not necessary to maintain proper control of the process
B) It produces more waste than conventional activated sludge process
C) It has low F/M ratio
D) It has low MLSS concentration
C) It has low F/M ratio (v.1 pg 257)
What type of disinfection is gaining popularity, and expected to become a practical alternative to chlorination?
A) Sulfur dioxide
B) Ultraviolet (UV) disinfection
C) Aqueous ammonia
D) Caustic soda
B) Ultraviolet (UV) disinfection (v.1 pg 303)
Where is the proper sampling location for an effluent from a wastewater treatment plant?
A) Next to the chlorinator equipment
B) At the end of a solids handling facility
C) Prior to discharge into receiving waters
D) At the head of a chlorine contact chamber
C) Prior to discharge into receiving waters
What is true if the F/M ratio increases?
A) Less DO is required
B) Less BOD is available
C) DO will not be affected by an increase in F/M ratio
D) More DO is needed
D) More DO is needed (v.2 pg 53)
Who must be included in a hearing conservation program to prevent hearing loss?
A) Employees whose normal noise exposure equals or exceeds 65 decibels
B) Employees whose normal noise exposure equals or exceeds an 8 hour time weighted average of 85 decibels
C) Employees whose normal noise exposure exceeds 45 decibels at any time
D) Employees whose normal noise exposure exceeds and 8 hour time weighted average of 25 decibels
B) Employees whose normal noise exposure equals or exceeds an 8 hour time weighted average of 85 decibels (v.2 pg 277)
What is a major cause of repeated sludge bulk?
A) High pH
B) High DO
C) High food to mircoorganism loading rates
D) High nutrient concentration
C) High food to mircoorganism loading rates (v.2 pg 71)
How can the efficiency of a trickling filter be improved?
A) Raise the distributor arm
B) Reduce the size of the ventilation ports
C) Decrease the amount of the filter media
D) Add recirculation
D) Add recirculation (v.1 pg 175)
During the day, what typically happens to a pond as a result of the algae?
A) Algae uses carbon dioxide, which raises pH
B) Algae produces carbon dioxide, which lowers pH
C) Algae consumes carbon dioxide, which lower pH
D) Algae releases carbon dioxide, which raises pH
A) Algae uses carbon dioxide, which raises pH (v.1 pg 299)
What should be done to find a small chlorine leak?
A) Spray hypocloric acid near the suspected leak
B) Tie a rag on a stick, dip the rag in a strong ammonia solution, and hold the rag near the suspected points
C) Release carbon dioxide to trace the leak
D) Apply a small quantity of citric acid near the leak
B) Tie a rag on a stick, dip the rag in a strong ammonia solution, and hold the rag near the suspected points (v.1 pg 386)
What should you do if there is a thick, dark foam on the surface of an aeration tank?
A) Increase the sludge wasting
B) Decrease sludge wasting
C) Maintain current MLSS concentration
D) Increase the mircoorganism population
A) Increase the sludge wasting (v.2 pg 53)
Why is mixing important in an anaerobic digester?
A) Increases the build up of grit
B) Speeds up digestion rate
C) Achieves heterogeneous content in the digester
D) Forms a scum blanket
B) Speeds up digestion rate (v.2 pg 176)
Where is the correct location for a vent inside a room storing chlorine gas?
A) 12 inches below the ceiling
B) At nose level
C) Within 12 inches of the floor
D) At the highest point in the room
C) Within 12 inches of the floor (v.1 pg 396)
What is the purpose of the seal at the stuffing box in a pump?
A) Increases the discharge flowrate of the pump
B) Minimizes cavitation
C) Increases brake horsepower
D) Lubricates the packing
D) Lubricates the packing (v.2 pg 344)
What is the incubation period for the BOD test?
A) Five days +/- 3 hours
B) Five days +/- 1 hours
C) Five days +/-4 hours
D) Five days +/- 2 hours
A) Five days +/- 3 hours (v.2 pg 574)
What could happen if you are exposed to very high concentration of hydrogen sulfide?
A) Swelling of the hand
B) Numbness of the legs
C) It could quickly lead to death
D) Develop skin rash
C) It could quickly lead to death (v.2 pg 268)
What causes primary effluent to become black and odorous?
A) Excessive sludge pumping
B) Oil leak from the sludge pump
C) Crack in the launder
D) Improper sludge removal from the clarifier
D) Improper sludge removal from the clarifier (v.1 pg 123)
What is a biomass?
A) Bacteria that change ammonia into oxidized nitrogen
B) Organisms that grow in a thread or filamentous form
C) A mass of organic material consisting of living organisms that feed on the wastes in sewage
D) Wastes such as sand, salt, and calcium that are present in the plant influent
C) A mass of organic material consisting of living organisms that feed on the wastes in sewage (v.2 pg 816)
What is the color of a pond that is operating properly?
A) Brown
B) Deep green color
C) Clear
D) Tan
B) Deep green color (v.1 pg 309)
What does healthy activated sludge smell like?
A) Chlorine
B) Raw sewage
C) Rotten eggs
D) Earthy
D) Earthy
Which law regulates wastewater discharge to receiving water?
A) Wastewater Act
B) Clean Water Act
C) National Discharge Act
D) Federal Effluent Act
B) Clean Water Act
1 mg/l is the same as 1 part per billion (ppb)
True or False
False (v.1 pg 468)
A SCADA system is capable of monitoring and controlling equipment from a remote location
True or False
True (v.2 pg 627)
A Discharge Monitoring Report is typically submitted to the regulatory agency on a daily basis
True or False
False
A mechanical seal is used to prevent leaks between the pump casing and shaft.
True or False
True (v.2 pg 356)
Alkalinity is the capacity of a liquid to neutralize a base.
True or False
False (v.2 pg 813)
Typical mixed liquor suspended solids concentration is 1,000 to 4,500 mg/l.
True or False
True (v.2 pg 54)
Turbidity is caused by suspended matters.
True or False
True (v.2 pg 606)
Algae is not essential to the successful operation of both aerobic and facultative ponds.
True or False
False (v.1 pg 299)
The addition of acid and CO2 will lower the pH of wastewater.
True or False
True (v.1 pg 299)
Hydrogen sulfide will deteriorate concrete structures.
True or False
True (v.1 pg 20)
The higher the pH, the better the disinfection
False (v.1 pg 352)
Maintain a dissolved oxygen concentration of 12 to 14 mg/l in the aeration tank.
True or False
False (v.2 pg 53)
When the velocity of the wastewater in a clarifier is greater in some sections than others, it will lead to short-circuiting.
True or False
True (v.1 pg 135)
The F/M ratio will decrease when the microorganism population in the aeration tank increases.
True or False
True (v.2 pg 16)
Algae growth will be faster when there is less sunlight.
True or False
False (v.1 pg 309)
The higher the temperature, the more rapid the rate of disinfection.
True or False
True (v.1 pg 352)
One of the benefits of recirculation for a trickling filter is that it decreases the contact time of the wastewater with the biological film.
True or False
False (v.1 pg 175)
Maintaining a constant temperature in an anaerobic digester is one way to prevent foaming from recurring.
True or False
True (v.2 pg 187)
Preventative maintenance is a proactive, programmed, and systematic approach to maintenance.
True or False
True (v.2 pg 718)
Abnormal operation in a pond will not occur if it is overloaded with BOD.
True or False
False (v.1 pg 307)
Anaerobic decomposition of sewage will release hydrogen sulfide.
True or False
True (v.1 pg 20)
Always pour water into acid, and never the other way around.
True or False
False (v.2 pg 302)
Scum escaping in the clarifier effluent could be caused by hydraulic overload.
True or False
True (v.1 pg 124)
Operate an activated sludge system at low MCRT if you have limited aeration capacity.
True or False
True (v.2 pg 59)
Chlorine gas is brown in color.
True or False
False (v.2 pg 268)
Typical suspended solids concentration of domestic influent wastewater is 150 to 400 mg/l.
True or False
True (v.2 pg 54)
Poor ventilation of a trickling filter could lead to odor problems.
True or False
True (v.1 pg 193)
Sulfur dioxide is used to dechlorinate the effluent prior to discharge to protect aquatic organisms in the receiving waters.
True or False
True (v.1 pg 401)
MCRT describes the average residence time of the activated sludge particle in the return sludge pipe.
True or False
False (v.2 pg 522)
Free chlorine combines with water to form hypochlorous and hydorchloric acids.
True or False
True (v.1 pg 349)
The trickling filter can be controlled by changing the loadings based on sludge age, F/M ratio, or MCRT.
True or False
False (v.2 pg 58)
The MPN test for coliform does not test for individual pathogenic microorganisms, but uses coliform as an indicator organism to estimate the microorganism population.
True or False
True (v.1 pg 352)
Mixed liquor volatile suspended solids (MLVSS) is used to determine the amount of microorganisms in the aeration tank to treat the incoming waste.
True or False
True (v.2 pg 58)
A manhole, sump, or vault, can be entered without the following confined space entry procedures if it appears safe.
True or False
False (v.2 pg 271)
An increase in the volatile acids/alkalinity ratio in an anaerobic digester indicates that a problem is developing.
True or False
True (v.2 pg 191)
Chain driven scrappers called flights are commonly used as mechanical grit collectors.
True or False
True (v.1 pg 87)
A facultative bacteria is capable of living under an aerobic condition, but not in an anaerobic condition.
True or False
False (v.2 pg 826)
An impeller is an important part of a centrifugal pump that spins the liquid at high speed.
True or False
True (v.2 pg 339)
Hot bearings in a blower could be caused by defective bearings.
True or False
False (v.2 pg 80)
Class A fire extinguisher should be used for an electrical fire.
True or False
False (v.2 pg 496)
Scum from primary clarifiers consists mainly of grease and other floatable materials.
True or False
True (v.2 pg 183)
One of the ways to resolve an increase in the volatile acid/alkalinity ratio in an anaerobic digester is to decrease raw sludge feed rates.
True or False
True (v.2 pg 191)
Sludge will not become septic when it remains in a channel or basin for an extended period of time.
True or False
False (v.2 pg 72)
Shallow ponds that are used to treat wastewater are typically 3 to 5 feet deep.
True or False
True (v.1 pg 294)
A slight seal leakage should be observed when a pump is operating to keep the packings cool.
True or False
True (v.2 pg 414)
Total solids = volatile solids + suspended solids
True or False
False (v.1 pg 22)
The purpose of sludge wasting in an activated sludge process is to control the amount of solids in the primary treatment process.
True or False
False (v.2 pg 57)
Chlorine gas in not flammable.
True or False
True (v.2 pg 268)
Screening is a part of the pretreatment process that removes larger debris, such as rocks, cans, and bottle.
True or False
True (v.1 pg 65)
The best velocity through a grit chamber is 3 foot per second.
True or False
False (v.1 pg 84)
What is the main purpose of the activated sludge process?
A) Removal of sand and pebbles
B) Removal of settleable solids and floating scum
C) Organic solids are liquefied and the solids volume is reduced
D) Removal of soluble or finely divided suspended materials that were not removed by the previous treatment.
D) Removal of soluble or finely divided suspended materials that were not removed by the previous treatment. (v.2 pg 16)
Where is the primary sludge typically pumped to ?
A) Grit classifier
B) Centrifuge
C) Sludge digester
D) Sludge drying bed
C) Sludge digester (v.2 pg 148)
What problem is caused by denitrification?
A) Excessive settling of solids
B) Rising sludge in secondary clarifier
C) Very short detention time
D) Conversion of ammonia to oxidized nitrogen
B) Rising sludge in secondary clarifier (v.2 pg 73)
What condition is necessary to perform a BOD test?
A) 5 days at 20 degrees Celsius
B) 5 days at 25 degrees Celsius
C) 5 days at 30 degrees Celsius
D) 5 days at 35 degrees Celsius
A) 5 days at 20 degrees Celsius (v.2 pg 574)
What is a fusible plug?
A) a plug on the bottom of a valve to drain sludge during maintenance
B) a plug that can be fused to a diffuser in an aeration tank to permanently seal the outlet
C) a safety device used to prevent build up of excessive pressure in a chlorine cylinder
D) a plug used to seal a leak on a polymer storage tank
C) a safety device used to prevent build up of excessive pressure in a chlorine cylinder (v.1 pg 378)
What is usually the last indicator to change in an anaerobic digester that is becoming sour?
A) Volatile acid/alkalinity ratio
B) Temperature
C) Color
D) pH
D) pH (v.2 pg 192)
What information is needed to calculate the F/M ratio?
A) BOD and MLSS
B) BOD and MLVSS
C) TSS and MLSS
D) MLSS and settled sludge volume
B) BOD and MLVSS (v.2 pg 16)
Which chemical is commonly used to control hydrogen sulfide gas?
A) Chlorine
B) Ammonia
C) Carbon dioxide
D) Sodium dioxide
A) Chlorine (v.2 pg 506)
What could cause a trickling filter to operate less effectively?
A) Blower inefficiency
B) Recirculation
C) Plastic Media
D) Ponding
D) Ponding (v.1 pg 175)
What is MPN?
A) A type of surfactant found in wastewater
B) A clump of organic material
C) Most Probable Number of coliform group organisms per unit volume of sample water
D) A number that indicates the tendency of activated sludge solids to thicken
C) Most Probable Number of coliform group organisms per unit volume of sample water (v.2 pg 835)
What is true regarding dissolved solids?
A) They will get caught on a filter
B) They are often called colloidal particles
C) They will pass through a filter
D) They are all inorganic solids
C) They will pass through a filter (v.1 pg 21)
Why is chlorine sometimes added at the headworks of the plant?
A) To address denitrification
B) Control odor
C) To address sludge bulking
D) Control fly problems
B) Control odor (v.1 pg 354)
What is the purpose of a launder in a primary clarifier?
A) Collects the primary effluent that flows over the weir and conveys it towards the next treatment process
B) A pipe that conveys wastewater to the influent of the clarifier
C) Blades that scrape sludge from the bottom of the clarifier to the sump
D) A power unit that rotates the collector
A) Collects the primary effluent that flows over the weir and conveys it towards the next treatment process (v.1 pg 115)
What is the best way to communicate important information to employees?
A) Memo
B) Meeting in-person
C) Bulletin board in break room
D) Send an email
B) Meeting in-person (v.2 pg 708-710)
What problems might arise from tightening a gland in a pump?
A) Excessive leakage
B) Water hammer
C) Wear on the shaft or shaft sleeve
D) Cavitation
C) Wear on the shaft or shaft sleeve (v.2 pg 344)
What could the oxygen uptake rate test be used for?
A) Determine SVI
B) Obtain the F/M ratio
C) Obtain pH of the wastewater
D) Detect toxicity in the activated sludge process
D) Detect toxicity in the activated sludge process
What does anaerobic bacteria require for metabolism?
A) Dissolved oxygen
B) Oxygen from nitrate
C) They obtain oxygen by breaking down chemical compounds that contain oxygen, such as sulfate
D) Carbon
C) They obtain oxygen by breaking down chemical compounds that contain oxygen, such as sulfate (v.2 pg 814)
Which of the following is used to dewater sludge?
A) All choices (B,C,D)
B) Drying bed
C) Centrifuge
D) Vacuum filter
A) All choices (B,C,D) (v.1 pg 49)
Which of the following is true about algae in a pond?
A) During the day, it consumes oxygen and releases CO2 for the bacteria in the pond
B) During the day, it consumes H2S and releases oxygen for the anaerobic bacteria in the pond
C) During the day, it consumes H2S and releases CO2 for the anaerobic bacteria
D) During the day, it consumes CO2 and releases oxygen for the aerobic bacteria in the pond
D) During the day, it consumes CO2 and releases oxygen for the aerobic bacteria in the pond (v.1 pg 299)
What is the typical BOD in the secondary effluent?
A) between 50 to 100 mg/l
B) between 120 to 300 mg/l
C) Between 5 to 30 mg/l
D) Between 300 to 350 mg/l
C) Between 5 to 30 mg/l (v.2 pg 573)
What should be done to a chlorine container if liquid chlorine is leaking?
A) Turn it over so that the leaking side is on the bottom to seal the leak
B) Turn it to the side
C) Apply water on the chlorine leak to slow down the leakage
D) Turn it over so that the leaking side is on the top
D) Turn it over so that the leaking side is on the top (v.1 pg 388)
In a domestic wastewater system, how many pounds of oxygen are used each day by the microorganisms for each person using the system?
A) 1.3 lb/day/person
B) 0.17 lb/day/person
C) 2.4 lbs/day/person
D) 3.5 lbs/day/person
B) 0.17 lb/day/person (v.1 pg 326)
What terminology indicates the time required to fill a basin at a given flowrate?
A) Detention time
B) Short-Circuiting
C) Hydraulic loading rate
D) Weir overflow rate
A) Detention time (v.1 pg 513)
What could happen if the intake of a progressing cavity pump in not kept wet?
A) Increase in head
B) Damage to pump
C) Slight decrease in flowrate
D) Incremental increase in pressure
B) Damage to pump
How should you operate an anaerobic digester?
A) The rate of acid formation is more than the methane formation
B) The rate of acid formation is less than the methane formation
C) The rate of acid formation and methane formation are approximately equal
D) The rate of acid formation is predominant and methane formation is negligible
C) The rate of acid formation and methane formation are approximately equal (v.2 pg 148)
What is the purpose of a check valve?
A) To isolate a clarifier for maintenance
B) To stop flow from entering the headworks
C) To throttle flow by turning the nut
D) Prevent liquid form flowing in the reverse direction
D) Prevent liquid form flowing in the reverse direction (v.2 pg 369)
Which of the following is the best way to detect oxygen deficiency in a confined space?
A) Reliable and calibrated gas monitor/detector
B) Check for odor
C) Colormetric test
D) DPD
A) Reliable and calibrated gas monitor/detector (v.2 pg 267)
What should be done if filamentous organisms become a problem in the mixed liquor?
A) Lower the pH to 5
B) Lower the MCRT to less than 4 days
C) Decrease sludge return rate and increase wasting
D) Increase DO in aeration tank
D) Increase DO in aeration tank (v.2 pg 74)
What is the solids content of a good, thick primary sludge?
A) 0.1 to 0.8% dry solids
B) 1 to 2.5% dry solids
C) 4 to 8% dry solids
D) 8 to 10% dry solids
C) 4 to 8% dry solids (v.1 pg 130)
What must be done if you get chlorine in your eyes?
A) Wash eyes with HCl
B) Chlorine must be flushed immediately with large amounts of lukewarm water
C) Flush eyes with aqueous ammonia
D) Apply saline solution to affected eyes
B) Chlorine must be flushed immediately with large amounts of lukewarm water (v.1 pg 377)