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Which type of wastewater typically has the highest demand for oxygen?
1. Domestic
2. Storm water
3. Sanitary
4. Industrial
What is the correct incubation time and temperature for the BOD test?
1. 5 days at 20°F
2. 5 days at 20°C
3. 20 days at 5°C
4. 5 days at 68°C
What is the term for a liquid or sludge with a pH of 6.0?
1. Alkaline
2. Neutral
3. Basic
4. Acidic
What are very small, finely divided solids known as:
1. Settleable
2. Total
3. Colloidal
4. Inert
Which of the following best describes the term anoxic?
1. High dissolved oxygen is present.
2. Nearly anaerobic; very low dissolved oxygen but nitrates and/or nitrites are present.
3. Completely anaerobic; no dissolved oxygen, nitrates, or nitrites.
4. Nitrates are very low
Which is a higher life form in the activated sludge process ... a free swimming ciliate, a stalked ciliate, or a rotifer?
1. Free swimming ciliate
2. Stalked ciliate
3. Rotifer
4. They are all the same
Which term describes the conversion of ammonia nitrogen to oxidized nitrogen (usually nitrate)?
1. Fermentation
2. Log Growth
3. Nitrification
4. Denitrification
What will organic material do in a muffle furnace?
1. It will burn
2. It will not burn
3. It will chance to inorganic material
4. It will convert to dissolved solids
What is the best definition of a shock load?
1. An unexpected bump
2. A strong influent waste strength
3. A high concentration of TSS
4. A heavy truck load entering the plant
Which environment does filamentous bacteria like best?
1. Aerobic
2. Anaerobic
3. Facultative
4. Anoxic
What does one cubic foot of water weigh at 4°C?
1. 7.48 pounds
2. 8.34 pounds
3. 3.14159 pounds
4. 62.4 pounds
Which is a higher life form in the activated sludge process ... a free swimming ciliate or a stalked ciliate?
1. Free swimming ciliate
2. Stalked ciliate
3. They are both the same
4. Rotifers are younger than free swimmers
What does the "F" mean in the process parameter F/M ratio?
1. lbs/day volatile microorganisms
2. gpd plant flow
3. lbs/day influent CBOD₅
4. gpd waste sludge
Which type of sewer system contains domestic and industrial wastes?
1. Domestic wastewater system
2. Sanitary sewer system
3. Separate collection system
4. Combined sewer system
Which of the following lines are not used in transporting wastewater from its source in a home to the treatment plant?
1. House sewers
2. Lateral sewers
3. Trunk sewers
4. Storm sewers
Which gases do not usually cause problems in sewer collection systems?
1. Explosive gases
2. Hydrogen sulfide
3. Methane
4. Carbon dioxide
If a grit chamber is passing grit through the tank, what adjustment should be made to the velocity?
1. Increase the velocity
2. Decrease the velocity
3. The velocity must be higher than 3.0 fps to function
4. Velocity has nothing to do with grit removal
Which chemical is most commonly used in a wet scrubber odor control system when dealing with H₂S gas?
1. Polymer
2. Sodium hydroxide
3. Alum
4. Water
Is hydrogen sulfide (H₂S) lighter or heavier than the weight of air?
1. Lighter, it will rise
2. Heavier, it will settle
3. No difference, they are both the same weight
4. Hydrogen sulfide has a neutral weight
What may be the cause of gas and/or solids rise to the surface of a primary clarifier?
1. Too much sludge being removed
2. Poor screenings removal
3. Aeration SRT too low
4. Not enough sludge being removed
Given the following data, what is the surface loading rate for this primary clarifier?

• Primary clarifier diameter is 75 feet
• Tank depth is 13 feet
• Flow entering the clarifier is 2,587 gpm
1. 445 gpd/ft²
2. 844 gpd/ft²
3. 130 gpd/ft²
4. 1,157 gpd/ft2
What factor may be more important in maintaining efficient operation of a primary clarifier?
1. Location of the tank
2. Characteristics of the influent wastewater
3. Number of operators in the facility
4. Activated sludge SRT
What is the detention time in a primary clarifier that is 100 feet long, 25 feet wide, 14 feet deep, and the influent flow is 3.5 mgd?
1. 2.3 hours
2. 1.8 hours
3. 1.6 hours
4. 3.1 hours
What would be an unacceptable surface loading rate for a primary clarifier?
1. 400 to 600 gpd/ft²
2. 800 to 1,200 gpd/ft²
3. 100 to 300 gpd/ft²
4. 5,000 to 15,000 gpd/ft2
What factor may be the least important in maintaining efficient operation of a primary clarifier?
1. Proper design of the tank
2. Characteristics of the influent wastewater
3. Care given by the operator
4. F/M ratio
What may be the better method of removing primary sludge from the clarifier?
1. Large volumes only a few times each day
2. Small volumes once each day
3. Small volumes several times throughout the day
4. When the blanket gets 1 foot from the weir
What is a typical RAS to Q ratio for a conventional activated sludge process?
1. 75% to 150%
2. 25% to 50%
3. 1% to 2%
4. 75% to 100%
What process test can be performed in about 10 minutes and identifies the amount of oxygen being consumed by the microorganisms?
1. OUR, mg/l/hr
2. SVI ml/mg
3. SRT, days
4. F/M ratio
Which activated sludge growth phase is considered to have the highest F/M ratio, the lowest SRT, the highest sludge yield, and the best oxygen utilization efficiency?
1. High rate aeration
2. Extended aeration
3. Conventional aeration
4. Declining growth
Which group of bacteria is responsible for conversion of inorganic ammonia in wastewater?
1. Carbon eaters
2. Methanogens
3. Autotrophic
4. Heterotrophic
Which operating parameter is common for a conventional activated sludge process?
1. D.O. between 4.0 to 5.5 mg/l
2. SRT between 4 to 8 days
3. RAS to Q ratio about 150%
4. F/M ratio between 0.1 to 0.15
What is the aeration tank MLVSS concentration?
· Aeration MLSS is 2,500 mg/l
· Aeration MLSS is 77% Volatile
1. 3,500 mg/l
2. 3,000 mg/l
3. 1,925 mg/l
4. 2,625 mg/l
What is the percent CBOD₅ removal efficiency in this plant?
· Influent CBOD₅ is 200 mg/l
· Effluent CBOD₅ is 2.5 mg/l
1. 98.8%
2. 100%
3. 89.6%
4. 99.0%
What is the F/M ratio of the activated sludge process?
· Influent Flow is 5.75 mgd
· Influent CBOD5 is 200 mg/l
· Three (3) Aeration Tanks, Each @ 100 ft. Long, 25 ft. Wide, and 14 ft. Deep
· Aeration MLSS is 2,500 mg/l
· Aeration MLSS is 77% Volatile
1. a. 0.42
2. 0.21
3. 0.76
4. 1.31
What is the surface area of each secondary clarifier?
· Two (2) Secondary Clarifiers, Each @ 100 ft. Diameter and 14 ft. Deep
1. 7,850 ft²
2. 3,925 ft²
3. 491 ft²
4. 1,963 ft²
What is the SRT of this activated sludge plant?
· Influent Flow is 5.75 mgd · Effluent TSS is 2.0 mg/l
· Aeration MLSS is 2,500 mg/l · WAS Volume is 0.1 mgd
· Three Aeration Tanks, Each @ 100 ft. Long, 25 ft. Wide, and 14 ft. Deep
· WAS Concentration is 0.7% Total Solids
1. 12 days
2. 8.5 days
3. 6.5 days
4. 2.7 days
What is the surface settling rate of the secondary clarifiers?
· Influent Flow is 5.75 mgd
· Two (2) Secondary Clarifiers, Each @ 100 ft. Diameter and 14 ft. Deep
1. 293 gal/day/ft²
2. 3,414 gal/day/ft²
3. 366 gal/day/ft²
4. 73 gal/day/ft²
What is the solids loading rate on the secondary clarifiers?
Two (2) Secondary Clarifiers, Each @ 100 ft. Diameter and 14 ft. Deep
Aeration MLSS is 2,500 mg/l
Plant Flow is 5.75 mgd
RAS Rate is 65% of Q
1. 12.6 lbs/day/ft²
2. 8.6 lbs/day/ft²
3. 4.7 lbs/day/ft²
4. 9.9 lbs/day/ft²
What is the GSA (Gould Sludge Age) in this plant?
· Three (3) Aeration Tanks, Each @ 100 ft. Long, 25 ft. Wide, and 14 ft. Deep
· Aeration MLSS is 2,500 mg/l
· Influent Flow is 5.75 mgd
· Influent TSS is 180 mg/l
1. 6.4 days
2. 1.9 days
3. 8.0 days
4. 0.527 days
What is the SVI of this mixed liquor?
· Settleometer @ 30 Minutes is 425 ml/l
· Aeration MLSS is 2,500 mg/l
1. 5.8
2. 75
3. 125
4. 170
How many gallons of WAS should be removed if a 10 day SRT is the desired target?
· Aeration MLSS is 2,500 mg/l
· Aeration Volume is 0.7854 mg
· WAS Concentration is 0.7% Total Solids
· WAS Volume is 0.1 mgd
1. 7,642 gpd
2. 28,051 gpd
3. 14,025 gpd
4. 16,428 gpd
What is the detention time in the aeration system? (not including RAS flow)
· Three Aeration Tanks, Each @ 100 ft. Long, 25 ft. Wide, and 14 ft. Deep
· Influent Flow is 5.75 mgd
1. 1.1 hours
2. 10.9 hours
3. 3.3 hours
4. 9.0 hours
What is the total length of weir for the secondary clarifiers?
· Two (2) Secondary Clarifiers, Each @ 100 ft. Diameter and 14 ft. Deep
· Each Secondary Clarifier has a Single Weir Around the Tank's
Circumference
1. 628 feet
2. 912 feet
3. 314 feet
4. 157 feet
Given the following data, is the F/M ratio within an acceptable range?

· Conventional Aeration
· SRT is 2.8 days
· SVI is 170
· Aeration detention Time is 3.3 hours
· F/M Ratio is 0.76
1. Yes
2. No
3. The effluent quality is very poor
4. Not enough data to calculate the F/M ratio
Given the following data, is the SRT within an acceptable range?
· Conventional Aeration
· SVI is 170
· Aeration detention Time is 3.3 hours
· F/M Ratio is 0.76
· SRT is 2.8 days
1. Yes
2. No
3. The effluent quality is very poor
4. Not enough data to determine the SRT
What is the principal function of slimes that accumulate on the trickling filter media?
1. To filter out bacteria through sand media
2. To remove large solids particles
3. To oxidize organic material
4. None of the above
What does a recirculation rate of 2:1 mean?
1. There is 1 mg/l BOD₅ being loaded to 1 ft² of media
2. The total flow applied to the trickling filter is 2 mgd
3. The total flow applied to the trickling filter is twice the volume of the raw wastewater flow
4. The flow applied to the trickling filter is three times the volume of the raw wastewater flow
What is the total flow rate applied to a trickling filter that receives a raw wastewater flow of 0.5 mgd, and has a recirculation rate of 1:1?
1. 1.0 mgd
2. 2.0 mgd
3. 1.5 mgd
4. 2.5 mgd
What is the principal make-up of slimes called that accumulate on the trickling filter media?
1. Amoeba culture
2. Zoogleal mass
3. Rotifer growth
4. None of the above
What type of gas is generated in largest quantities as the result of anaerobic decomposition taking place in a stabilization lagoon?
1. Hydrogen sulfide
2. Carbon dioxide
3. Methane
4. Nitrogen
What problems can be caused in a lagoon with long, hot operational periods?
1. All bacteria may die
2. Excessive algae growth overloads the lagoon
3. Water level gets too low
4. The D.O. gets too high
What type of pond has high D.O. conditions throughout the pond?
1. Aerobic
2. Unaerated
3. Fermentation
4. Facultative
Which time of day will generally have the lowest D.O. in an unaerated stabilization pond?
1. 12 midnight
2. 3 p.m.
3. 3 a.m.
4. 6 a.m.
Which group of bacteria are most responsible for removal of phosphorus in the BNR activated sludge process?
1. SVI
2. GSA
3. Autotrophic
4. PAO
Which zone of a BNR plant produces a release of phosphorus and is responsible for conditioning the phosphorus for later uptake in the downstream zones?
1. Anoxic
2. Fermentation
3. Aerobic
4. Reaeration
Which zone produces the largest amount of biological nitrification?
1. Fermentation
2. Anoxic
3. Aerobic
4. Reaeration
How much alkalinity is required to convert 1.0 pound of ammonia-nitrogen during the nitrification process?
1. 7.2 lbs
2. 8.34 lbs
3. 7.48 lbs
4. 4.6 lbs
Which chemical is more commonly used to remove phosphorus from wastewater?
1. Chlorine
2. Sodium Hydroxide
3. Polymer
4. Aluminum sulfate
Where does "luxury phosphorus uptake" occur in the Bardenpho process?
1. Aerobic
2. Fermentation
3. Anoxic
4. Reaeration
How much alkalinity is put back into the MLSS for each pound of nitrate used as a source of oxygen during the denitrification process?
1. 4.6 lbs
2. 7.2 lbs
3. 2.6 lbs
4. 3.6 lbs
Which major reaction is most likely to occur in an anoxic zone of a BNR process?
1. Nitrification
2. Phosphorus uptake
3. Denitrification
4. Reaeration
What happens to the activity rate of activated sludge microorganisms when the temperature decreases?
1. The activity rate decreases
2. The activity rate increases
3. The activity rate remains the same
4. Temperature has no effect on activity rate
What is the amount of oxygen credit received for each ppm of nitrate used as a source of oxygen in the denitrification process?
1. 2.8 pounds
2. 3.6 pounds
3. 4.6 pounds
4. 7.2 pounds
Which best describes the denitrification cycle?
1. Nitrates are converted to free nitrogen gas
2. Ammonia is converted to nitrites and then to nitrates
3. Ammonia is converted to nitrates and then to nitrites
4. Nitrates are converted to ammonia and then to nitrites
Which gas can cause clumps of sludge to rise in a secondary clarifier as a result of denitrification?
1. Oxygen
2. Carbon dioxide
3. Hydrogen sulfide
4. Nitrogen
Which blanket detention time method is commonly used in the gravity thickening process?
1. F/M
2. SRT
3. SVRT
4. OUR
What generally happens to the thickened sludge concentration if too much sludge is removed from the bottom of a gravity thickener?
1. It gets thicker
2. It gets thinner
3. Pumping has no affect on the thickened sludge concentration
4. The blanket gets deeper
Given the following data, what is the total volume of this gravity thickener (including the cone volume)?

· 50 ft. diameter
· 12 ft. SWD
· 3 ft. sludge blanket depth
· 4 ft. cone depth
1. 176,154 gals
2. 19,578 gals
3. 324,578 gals
4. 195,727 gals
Given the following data, what is the detention time of the sludge blanket in this gravity thickener?

• 50 ft. diameter
• 3 ft. sludge blanket depth
• 4 ft. cone depth
• 100 kgpd thickened sludge removed
1. 30.6 hours
2. 15.3 hours
3. 7.6 hours
4. 22.9 hours
What device is used to blend polymer and sludge feed before it is applied to the GBT?
1. Retention vessel
2. Venturi mixer
3. Chicane
4. Drive unit
What does a gravity belt thickener most represent?
1. The bottom half of a belt filter press
2. A centrifuge
3. The top half of a belt filter press
4. A standard gravity thickener
What usually happens to the thickened solids content when the belt speed is decreased in a GBT unit?
1. The solids content decreased
2. The solids content is cut in half
3. The solids content is increased
4. Belt speed has nothing to do with thickened sludge solids content
What will happen to a GBT that indicates the need to clean the washbox nozzles?
1. The cake will get too thick
2. The belt may break
3. The belt may have streaks of sludge
4. The filtrate my be too clear
Which test indicates the amount of time it takes for sludge particles to float to the surface in the DAF process?
1. Rise rate
2. D.O.
3. Centrifuge spindown
4. Microscopic exam
Will sludge be more likely to sink or float when its specific gravity is greater than 1.0?
1. It will sink
2. It will float
3. It will stay in suspension
4. Specific gravity has no affect on flotation
What is the principle concept of a centrifuge?
1. Dewaters through pressure shearing
2. Thickens through gravity drainage
3. Thickens through high speed spinning
4. Thickens through pressure filtration
What may be a major difference in operating a centrifuge for sludge thickening as compared to operating a gravity belt thickener?
1. The centrifuge requires a great deal more polymer to condition the sludge feed
2. The gravity belt thickener typically requires much more maintenance than a centrifuge
3. The centrifuge uses higher horsepower components than a gravity belt thickener
4. The capital cost of a gravity belt thickener is typically much higher than a centrifuge
What is the liquid effluent called in a centrifuge thickener?
1. Filtrate
2. Centrate
3. Supernate
4. Subnate
What may be a major difference with a centrifuge for sludge thickening as compared to a gravity belt thickener?
1. The centrifuge requires significantly more polymer to condition the sludge feed
2. The gravity belt thickener typically requires much more maintenance than a centrifuge
3. The centrifuge uses lower horsepower components than a gravity belt thickener
4. The capital cost of a gravity belt thickener is typically much less than a centrifuge
Which sludge thickening process has one continuous belt that allows gravity drainage and thickening of the sludge feed?
1. Gravity thickener
2. Gravity belt thickener
3. Dissolved air flotation
4. Centrifuge
Which sludge thickening process uses air-saturated recycle causing the sludge to rise to the surface of the tank for removal?
1. Gravity thickener
2. Gravity belt thickener
3. Dissolved air flotation
4. Centrifuge
Which sludge thickening process uses high speed spinning to accomplish thickening of the feed sludge?
1. Gravity thickener
2. Gravity belt thickener
3. Dissolved air flotation
4. Centrifuge
Which sludge thickening process uses an open tank, usually without any internal recycle streams, to accomplish thickening of the feed sludge?
1. Gravity thickener
2. Gravity belt thickener
3. Dissolved air flotation
4. Centrifuge
Which factor may have the least affect on the operation of an aerobic digester?
1. Digester detention time
2. Temperature of the digesting sludge
3. Oxygen transfer efficiency
4. Organic nitrogen level in the sludge feed
Which term is most related to vector attraction reduction in an aerobic digester?
1. Settleometer
2. Pathogen
3. SOUR
4. F/M
What happens to the pH of the digesting sludge if the aeration to an aerobic digestion system is periodically shut off?
1. The pH will decrease
2. The pH will increase
3. Aeration of the digester has nothing to do with pH
4. The alkalinity will decrease
Which statement best relates to adequate mixing in an aerobic digester?
1. Not necessary only dissolved oxygen is important
2. Accomplished with mechanical aerators only
3. Accomplished with diffused air systems only
4. Essential to ensure contact between organisms, food supply, and D.O.
What would happen to the pH of the digesting sludge if the aeration to an aerobic digestion system were never shut off?
1. The pH would be low
2. The pH would be high
3. Aeration of the digester has nothing to do with pH
4. The alkalinity would increase
What color should the digester gas be, as it is being burned in a waste gas burner, when the methane content is very high?
1. Yellow
2. Amber
3. Green
4. Blue
What device is designed to protect the anaerobic digester tanks and covers from damage?
1. Hot water system
2. Pressure/vacuum relief
3. Gas recirculation compressor
4. Drip trap
What can cause a rise in the volatile acids/alkalinity ratio in an anaerobic digester?
1. Underfeeding the primary digester
2. Hydraulically overloading the primary digester
3. Organically underloading the primary digester
4. Adequate mixing of the primary digester
Which test is not recommended to use for process control of an anaerobic digestion process?
1. pH
2. Acid/alkalinity
3. Volatile reduction
4. Methane gas production
What should be the minimum acceptable level for volatile solids reduction in a properly operated anaerobic digester … in order to satisfy the rules on vector attraction reduction?
1. 95%
2. 5%
3. 38%
4. 76%
Which anaerobic digestion temperature range represents stable Thermophilic conditions?
1. 75 to 90°F
2. 120 to 135°F
3. 85 to 100°F
4. 110 to 120°F
What color may the digested sludge be in a poorly operated anaerobic digestion process?
1. All black
2. White
3. Green with black streaks
4. Brown with gray streaks
Why would sodium bicarbonate or lime be added to an anaerobic digester?
1. To neutralize high acid production
2. To decrease alkalinity
3. To decrease pH
4. To decrease volatile reduction
What color may the digester gas be, as it is being burned in a waste gas burner, when the methane content is very low?
1. Yellow
2. Black
3. Green
4. Blue
What is a common pH range in a properly operated anaerobic digester?
1. 7.5 to 8.5
2. 6.8 to 7.2
3. 5.8 to 6.2
4. 8.2 to 9.1
What are the two (2) basic types of lime that can be used in the lime stabilization process?
1. Hard lime and soft lime
2. Quicklime and Hydrate lime
3. Limestone and pebble lime
4. Calcium hydroxide and ferric chloride
What are the vector attraction reduction requirements for lime stabilization to accomplish Class B stabilization standards?
1. Raise the sludge pH to no more than 11.0
2. Raise the sludge pH to at least 12 for the first 2 hours, and then at least 12.5 for the next 24 hours
3. Raise the sludge pH to between 10.0 to 10.5
4. Raise the sludge pH to at least 12 for the first 2 hours, and then at least 11.5 for the next 22 hours
What is a typical percent solids in the pre-cake leaving the gravity section of a belt filter press?
1. 2% to 4%
2. 30% to 50%
3. 15% to 20%
4. 8% to 10%
What may be an anticipated result of reducing belt speed of a belt filter press?
1. Create a larger floc
2. Improve gravity filtration and create higher cake solids
3. Create poor gravity filtration and create lower cake solids
4. Produce a lower percent solids in the gravity section sludge
What is the water called that is removed by the belt press?
1. Mixed liquor
2. Effluent
3. Filtrate
4. Cake
What is polymer called when it has a positive charge?
1. Anionic
2. Reverse negative
3. Non-ionic
4. Cationic
What may be the result if the system tension pressure of a belt filter press is increased too much?
1. The floc size may be too small
2. The belts may blind
3. Gravity filtration will be too clear
4. The cake solids may be too high
What chemical is commonly used to condition the sludge being applied to a belt filter press?
1. Polymer
2. Chlorine
3. Lime
4. Sodium hydroxide
What may be the result if the belt speed, on a belt filter press, is too slow?
1. The floc size may be too small
2. Gravity filtration may be poor
3. The cake solids may be low
4. The gravity zone may flood
What may be an anticipated result of increasing the belt speed of a belt filter press?
1. Create a larger floc
2. Improve gravity filtration and create higher cake solids
3. Decrease gravity drainage time and decrease the cake solids
4. Create a smaller floc
What is an alternate method for vector attraction reduction in anaerobic digestion if the volatile solids reduction does not meet the required number?
1. Chlorine residual
2. SOUR
3. Extended 40 day bench test
4. Ammonia-nitrogen
What is the fecal coliform limit to meet standards for Class A biosolids?
1. 1,000 #/gram TS
2. 10,000 #/gram TS
3. 1,000,000 #/gram TS
4. 2,000,000 #/gram TS
Which is the EPA part that provides rules and regulation for the disposal of wastewater residuals?
1. 305 rule
2. 640 rule
3. 736 rule
4. 503 rule
What is the fecal coliform limit to meet standards for Class B biosolids?
1. 1,000 #/gram TS
2. 10,000 #/gram TS
3. 1,000,000 #/gram TS
4. 2,000,000 #/gram TS
Where is gas chlorine withdrawn from in a one-ton container?
1. From the bottom valve
2. From the top valve
3. From top or bottom valves
4. Gas cannot be withdrawn from a one-ton container
What does this formula represent?
Demand + Residual =
1. Breakpoint
2. Dosage
3. Supply
4. Combined
Which component in a chlorine evaporator is responsible for reducing the chlorine gas pressure down to 1 atmosphere?
1. PRV
2. O-ring
3. SBR
4. Gas injector
What pipe material is used to convey chlorine (liquid or gas) under pressure from one-ton containers to downstream equipment components?
1. Black iron pipe
2. PVC pipe
3. Ductile clay pipe
4. Prestressed concrete pipe
What type of chlorine residual is attained after the breakpoint is achieved?
1. Combined
2. Total
3. Free
4. Mono
What is the detention time of a chlorine contact chamber that is 100 feet long, 15 feet wide, 9 feet deep, and has a plant flow rate of 4.2 mgd?
1. About 2 hours
2. About 76 minutes
3. About 35 minutes
4. About 15 minutes
What does this formula represent?
Contact Chamber Volume, ft³ ÷ 92.84 cfm/mgd x Flow, mgd
1. Surface settling rate
2. Detention time in hours
3. Volume of contact chamber in gallons
4. Detention time in minutes
What is the formula that defines chlorine demand?
1. Demand - supply = residual
2. Supply - residual = demand
3. Supply x demand = residual
4. Demand + supply = residual
What type of chlorine comes in solid, or dry form?
1. Sodium hypochlorite
2. Ferric chloride
3. Calcium hypochlorite
4. Aluminum sulfate
What pipe material can used to convey chlorine gas, after the pressure has been reduced to one atmosphere, from one-ton containers to downstream equipment components?
1. Only black iron pipe
2. PVC pipe
3. Ductile clay pipe
4. Prestressed concrete pipe
Which type of chlorine only comes in liquid form?
1. Ferric chloride
2. Calcium hypochlorite
3. Sodium hypochlorite
4. Caustic soda
Which component may create the highest maintenance requirement in a UV disinfection system?
1. UV monitor
2. UV lamp
3. UV abilitator
4. UV residual
What type of channel can UV disinfection be operated in?
1. Open channel only
2. Closed channel only
3. Pipeline only
4. Either an open channel, a closed channel, or a pipeline
What happens to the quality of the effluent after ozone is added to it?
1. The color and odor are increased
2. The color gets darker but the odor is neutral
3. The color is unaffected but the odor is greater
4. The color improves and the odor is neutral
What should be done to air before it is applied to an air feed ozone generator?
1. Cooled, separated and dried
2. Dried and cooled
3. Cooled and separated
4. Separated and dried
What affect on disinfection does ozone have before the ozone demand has been satisfied?
1. Relatively little disinfection power occurs before the ozone demand is satisfied
2. Very high disinfection power occurs immediately
3. The ozone demand does not affect the disinfection power of ozone
4. Bacteria are immediately killed before the ozone demand is satisfied
Which components are incorporated in a typical centrifugal pump?
1. Check valve
2. Impeller
3. Bearings
4. All of the above
Which component may prevent excessive grease pressure from damaging the bearings?
1. Vibration sensor
2. Relief plug
3. Temperature sensor
4. Oil pressure gauge
What component of a pump keeps the material in the discharge pipe from emptying out through the pump suction when the pump is off?
1. Pressure relief
2. Check valve
3. Mechanical seal
4. Volute
What may be the problem if a centrifugal pump rotates freely but will not discharge water?
1. Partially clogged impeller or clogged suction pipe
2. Impeller is jammed frozen or the discharge pipe is plugged
3. Cavitation
4. NPSH too high
What statement describes a reciprocating pump?
1. Has a rotating impeller
2. Has a piston that moves back and forth
3. Has two plug valves on the inlet
4. Is designed to pump grit
Which item may be the most important when determining the track record of a piece of equipment?
1. Equipment data
2. Maintenance frequencies
3. Maintenance equipment history
4. List of emergency phone numbers
Which type of flow meter uses an open channel to measure the flow rate?
1. Magnetic
2. Venturi
3. Parshall flume
4. Differential pressure
What does a closed circuit mean in electrical terms?
1. That power is disengaged ... dead
2. That power is off
3. That power is engaged ... live
4. The term “closed” has nothing to do with electricity
Why are flow measurements important?
1. They help to determine D.O.
2. They help to determine loading rates
3. They help to determine nitrate levels
4. They help to determine suspended solids removal
Given the following data, what should the annual chlorine budget be in a leap-year?

• Plant Flow = 1.25 mgd
• Preliminary Treatment Chlorine Dosage = 7.5 mg/l
• Odor Control Scrubber = 25 ppd
• RAS Chlorine Dosage = 1.2 mg/l
• Effluent Chlorine Dosage = 8.75 mg/l
• Chlorine Cost = $0.25 per Pound
• 10% increase for higher demand periods
1. $20,826
2. $44,542
3. $18,743
4. $23,847
Which statement is true regarding sample collection?
1. Collect the sample when the operator has time
2. Collect the sample at a convenient location in the plant
3. Collect the sample so it is representative of the wastewater being tested
4. Collect the sample bare-handed
What is the term when ammonia-N, nitrate-N and nitrite-N are added together?
1. TN
2. TIN
3. NO³
4. TKN
What is the term that identifies the probable number of fecal coliform in wastewater effluent?
1. COD
2. MPN
3. pH
4. D.O.
Which lab test requires the use of an analytical balance, a drying oven, filter papers, a muffle furnace, and a desiccator?
1. VSS
2. TS
3. BOD⁵
4. Settleable solids
What is the result of this formula?
Total Solids - Fixed Solids =
1. Total suspended solids
2. Volatile solids
3. Fixed suspended solids
4. Settleable solids
What is the TSS concentration, given the following data:

• 50 ml of sample
• Tare weight of filter is 11.8873 grams
• Final weight of filter after drying is 12.2255 grams
1. 2,624 mg/l
2. 13,012 mg/l
3. 6,764 mg/l
4. 1,312 mg/l
What is the standard temperature in the muffle furnace for the VSS test?
1. 20 to 25°C
2. 110 to 115°C
3. 103 to 105°C
4. 545 to 555°C
What is the temperature of the incubation for a BOD test?
1. 20°F
2. 5°C
3. 25°F
4. 68°F
How is fecal coliform identified in the membrane filter test method?
1. The number of colonies grown on the filter paper
2. The number of positive tubes
3. The number of negative tubes
4. The number of colonies grown in the tube
What is the standard temperature in the drying oven for the TSS test?
1. 20 to 25°C
2. 110 to 115°C
3. 103 to 105°C
4. 545 to 555°C
What temperature should samples be stored in a sample refrigerator?
1. 10°C
2. 1°C
3. 4°C
4. 4°F
What will be the volume of a tank if the flow entering is 5 mgd and the detention time is 1.5 hours?
1. 583,000 gals
2. 1.2 mg
3. 0.3957 mg
4. 312,500 gals
What is the volume in gallons occupied by 45,000 cubic feet of water?
1. 336,600 gals
2. 168,300 gals
3. 375,300 gals
4. 2,808,000 gals
What is the fraction, in its least common denominator, for the decimal 0.42?
1. 42 ÷ 100
2. 42 ÷ 50
3. 21 ÷ 50
4. 84 ÷ 100
What does this formula represent?
1/3 π r² x depth, ft. x 7.48 gals/ft³
1. Volume of a cone in ft³
2. Volume of a circular tank in gallons
3. Volume of a sphere in gallons
4. Volume of a cone in gallons
How many pounds of solids are in a tank that is 100 feet long, 30 feet wide, 14 feet deep, and the MLSS concentration is 3,500 mg/l?
1. 19,170 lbs
2. 350 lbs
3. 1,226 lbs
4. 9,170 lbs
What is the demand for chlorine if the residual is 1.1 mg/l and the amount of chlorine applied is 7.4 mg/l?
1. 7.3 mg/l
2. 6.5 mg/l
3. 8.5 mg/l
4. 6.3 mg/l
Given the following data, how many gallons (not including the cone) are in this digester?

• 25 ft diameter
• 15 ft side water depth (and it’s full)
1. About 29,432 total gallons
2. About 55,048 total gallons
3. About 58,865 total gallons
4. About 3,817 total gallons
What is the consumption of chlorine used in 30 days if the flow rate is 2,500 gpm, and the dose rate is 8.5 mg/l?
1. 255 pounds
2. 7,661 pounds
3. 10,219 pounds
4. 8,824 pounds
What is the daily volume of sludge removed from a primary clarifier if the total dry lbs/day are 1,500, and the moisture content is 95.5%?
1. 1,679 gals/day
2. 6,769 gals/day
3. 3,997 gals/day
4. 1,998 gals/day
What is the moisture content of a sludge sample that measures 5.25% total solids?
1. 5.25%
2. 19%
3. .05%
4. 94.75%
What will the pressure gauge read on the suction of a pump if the pump is located at floor elevation of the tank and the tank has 15 feet of static water level?
1. About 34.7 psi
2. About 27.7 psi
3. About 12.0 psi
4. About 6.5 psi
Which dangerous gas will be more likely to settle near the bottom of a manhole?
1. Hydrogen sulfide
2. Methane
3. Nitrogen
4. Carbon dioxide
What does H₂S smell like at low concentrations?
1. Rotten eggs
2. Cabbage
3. No smell
4. Sweet orange
Which of the following is most explosive?
1. Pure digester gas
2. Digester gas mixed with methane
3. Digester gas mixed with air
4. Digester gas with high CO₂ content
Why should liquid chlorine never be trapped between two closed valves?
1. That is an acceptable condition
2. It will create a high oxygen demand
3. It will expand and blow the pipe apart
4. It gets very hot and will melt black iron pipe
Which practice is appropriate when working in a laboratory?
1. Carefully add acid to water
2. Hold glassware in your bare hands while heating it
3. Pipette samples by mouth
4. Carefully add water to acid
Which repair kit is used with a 150-pound cylinder of chlorine?
1. Kit A
2. Kit B
3. Kit C
4. None of the above
What procedure should be performed before entering a manhole that has been classified as a permit confined space?
1. Never wear a body harness
2. Testing the air with a gas detector is not necessary
3. Complete a confined space entry permit
4. Trained attendants are not required

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Wastewater Operator Study Guide Module 2 ... Practice Exam ... Happy Studying!Return to the Quiz Home Page by Clicking the Upper Right "x" on Your Browser

Wastewater Operator Study Guide Module 2 ... Practice Exam ... Happy Studying!
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