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What does the term adsorption mean?
1. Impregnate a liquid with air
2. The taking in of one substance in the body of another
3. To gather onto the surface of a substance
4. Soak like a sponge
What does the term loading refer to?
1. The pounds of MLVSS under aeration
2. The cfm of air supplied to the aeration tank
3. The pounds of BOD entering the aeration tank
4. The amount of waste sludge removed from the system
Which two age parameters are most similar to each other?
1. GSA and F/M ratio
2. SRT and MCRT
3. SRT and GSA
4. GSA and MCRT
What type of solids cannot be removed with typical effluent filters?
1. Settleable
2. Suspended
3. Total
4. Dissolved
Dissolve solids, like sugar in water, are not typically removed with effluent filtration.
What is not a typical loading equivalent in domestic wastewater?
1. About 0.17 lbs BOD/person/day
2. About 0.2 lbs TSS/person/day
3. About 100 gal/person/day
4. About 100 mg/l NH₃/person/day
What does the "M" mean in the process parameter F/M ratio?
1. lbs volatile microorganisms in aeration
2. gpd plant flow
3. gpd waste sludge leaving aeration
4. lbs/day influent BOD entering aeration
Which has a higher pH, sodium hydroxide or aluminum sulfate?
1. Aluminum sulfate
2. Sodium hydroxide
3. They are both the same
4. Alum has a high pH
What is a typical loading equivalent for TSS in domestic wastewater?
1. About 0.17 lbs/person/day
2. About 0.2 lbs/person/day
3. About 300 gal/person/day
4. About 200 mg/l/person/day
What type of solids are identified in a muffle furnace test?
1. Settleable
2. Suspended
3. Volatile
4. Dissolved
What is the main difference between a conventional activated sludge process and an advanced wastewater treatment process?
1. CBOD₅removal
2. TSS removal
3. Nitrogen & phosphorus removal
4. Metals removal
What is the minimum velocity in a sanitary sewer pipeline necessary to prevent settling of solids and debris?
1. 1 fps
2. 0.5 fps
3. 2 fps
4. 2 fpm
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
Which condition may be least affected if grit is not removed from the influent flow?
1. Erosion of valve seats
2. Take up valuable space in tanks
3. Poor CBOD₅removal efficiency
4. Damage pump impellers
Which may be the better adjustment if high H₂S levels were leaving a wet scrubber tower?
1. Decrease the tower pH
2. Add polymer into the tower
3. Increase the tower pH
4. Take the tower out of service
Given the following data, what percentage of BOD₅ is removed in this primary clarifier?
• Influent flow is 587 gpm
• Primary effluent BOD₅is 175 mg/l
1. 25%
2. 30%
3. 50%
4. 75%
How many total gals/day are removed from a primary clarifier using a double piston pump, given the following data?
• Gallons per stroke is 5.4
• Piston spm is 45
• Minutes per day are 358
1. 350,485 gpd
2. 158,498 gpd
3. 173,988 gpd
4. 86,994 gpd
What may be the cause if BOD₅ removal in a primary clarifier is less than 15%?
1. The plant is underloaded
2. The detention time is too short
3. The detention time is too long
4. 15% BOD₅ removal from a primary clarifier is normal
Given the following data, how many lbs/day of CBOD₅ are entering this primary clarifier?
• Flow entering the primary clarifier is 92.84 cfm
• Influent TSS concentration is 225 mg/l
1. 1,668 ppd
2. 2,769 ppd
3. 1,762 ppd
4. 1,877 ppd
What action should be performed to permanently increase the F/M ratio from 0.3 to 0.4?
1. Decrease WAS
2. Increase RAS
3. Increase RAS
4. Increase WAS
Which adjustments may be more appropriate to make if the aeration inlet OUR is 30 mg/l/hr, the aeration tank foam is very dark, and the aeration outlet ammonia level is too high?
1. Increase the RAS rate and decrease the D.O.
2. Increase the aeration air supply and increase the WAS rate
3. Decrease the WAS rate and increase the RAS rate
4. Take an aeration tank out of service
Which adjustment will create an increased contact time in the aeration tank?
1. Lower the weir
2. Increase the air supply rate
3. Decrease the WAS rate
4. Decrease the RAS rate
What adjustment may help if solids are rising in the secondary clarifier accompanied by large septic gas bubbles?
1. Increase aeration D.O.
2. Decrease RAS rate
3. Decrease WAS rate
4. Increase SRT
Which aeration foam may indicate an old sludge condition?
1. Black or dark brown in color
2. Light brown in color
3. White or very light in color
4. Light grey in color
What action should be performed to permanently reduce the F/M ratio from 0.4 to 0.3?
1. Decrease WAS
2. Increase RAS
3. Increase RAS
4. Increase WAS
Which operating parameter is not common for a conventional activated sludge process?
1. D.O. between 1.0 to 2.5 mg/l
2. SRT between 5 to 10 days
3. RAS to Q ratio about 50%
4. F/M ratio between 0.1 to 0.15
What does it mean when you observe red worms while performing a microscopic examination of the activated sludge?
1. The sludge is very young
2. The SRT is low
3. The sludge is very old
4. The F/M ratio is high
Given the following data what is the solids inventory of MLVSS in the aeration tanks?
• Each Aeration Tank has four (4) Passes, Each 125 ft. long, 25 ft. wide, and 15 ft. deep
• Aeration MLSS is 4,500 mg/l
• Aeration MLSS is 74% Volatile
1. 38,951 lbs
2. 104,587 lbs
3. 77,901 lbs
4. 105,272 lbs
How many lbs/day of CBOD₅ remain in the plant effluent?
· Influent Flow is 10.5 mgd
· Effluent CBOD₅ is 2.0 mg/l
1. 175 ppd
2. 21,893 ppd
3. 21,717 ppd
4. 131 ppd
How many gallons of WAS are removed from the process each day?
• Two (2) Complete Bardenpho Trains:
Each Fermentation Tank is 119 ft. long, 43 ft. wide, and 15 ft. deep
Each 1st Anoxic Tank is 119 ft. long, 38 ft. wide, and 15 ft. deep
Each Aeration Tank has four (4) Passes, Each 125 ft. long, 25 ft. wide, and 15 ft. deep
Each 2nd Anoxic Tank is 119 ft. long, 60 ft. wide, and 15 ft. deep
Each Reaeration Tank is 119 ft. long, 20 ft. wide, and 15 ft. deep
• Aeration MLSS is 4,500 mg/l
· WAS concentration is 1% TS
• WAS Volume is Based on 20 Day SRT (using all zones in each train)
1. 117,150 gpd
2. 239,769 gpd
3. 79,923 gpd
4. 159,846 gpd
What is the F/M ratio of the activated sludge process, using all zones except fermentation?
· Influent CBOD₅ is 250 mg/l
· Aeration MLSS is 4,500 mg/l
· Influent Flow is 10.5 mgd
· Aeration MLSS is 74% Volatile
1. 0.42
2. 0.13
3. 0.76
4. 0.11
What is the total surface area of all secondary clarifiers?
• Four (4) Secondary Clarifiers, Each @ 120 ft. Diameter and 14 ft. Deep
1. 7,850 ft²
2. 3,925 ft²
3. 11,310 ft²
4. 45,216 ft²
What is the MCRT of this activated sludge plant, using all 5 zones?
· Two (2) Complete Bardenpho Trains:
Each Fermentation Tank is 119 ft. long, 43 ft. wide, and 15 ft. deep
Each 1st Anoxic Tank is 119 ft. long, 38 ft. wide, and 15 ft. deep
Each Aeration Tank has four (4) Passes, Each 125 ft. long, 25 ft. wide, and 15 ft. deep
Each 2nd Anoxic Tank is 119 ft. long, 60 ft. wide, and 15 ft. deep
Each Reaeration Tank is 119 ft. long, 20 ft. wide, and 15 ft. deep
· WAS Volume is Based on 20 Day SRT (using all zones in each train)
· WAS Concentration is 1% and 70% Volatile
· Plant Flow is 10.5 mgd
· Effluent TSS/VSS is 1.5 mg/l
1. 13 days
2. 20 days
3. 14 days
4. 23 days
What is the surface settling rate of the secondary clarifiers?
· Influent Flow is 10.5 mgd
· Four (4) Secondary Clarifiers, Each @ 120 ft. Diameter and 14 ft. Deep
1. 232 gal/day/ft²
2. 3,414 gal/day/ft²
3. 366 gal/day/ft²
4. 928 gal/day/ft²
What is the solids loading rate on the secondary clarifiers?
• Influent Flow is 10.5 mgd
• Aeration MLSS is 4,500 mg/l
· RAS Flow 60% of Q
• Four (4) Secondary Clarifiers, Each @ 120 ft. Diameter and 14 ft. Deep
1. 12.6 lbs/day/ft²
2. 8.6 lbs/day/ft²
3. 13.9 lbs/day/ft²
4. 9.9 lbs/day/ft²
What is the GSA (Gould Sludge Age) in this plant (using all zones)?
• Two (2) Complete Bardenpho Trains:
Each Fermentation Tank is 119 ft. long, 43 ft. wide, and 15 ft. deep
Each 1st Anoxic Tank is 119 ft. long, 38 ft. wide, and 15 ft. deep
Each Aeration Tank has four (4) Passes, Each 125 ft. long, 25 ft. wide, and 15 ft. deep
Each 2nd Anoxic Tank is 119 ft. long, 60 ft. wide, and 15 ft. deep
Each Reaeration Tank is 119 ft. long, 20 ft. wide, and 15 ft. deep
• Aeration MLSS is 4,500 mg/l
• Influent Flow is 10.5 mgd
• Influent TSS is 230 mg/l
1. 17.4 days
2. 1.9 days
3. 8.0 days
4. 13.2 days
What is the SVI of this mixed liquor?
• Settleometer @ 30 Minutes is 325 ml/l
• Aeration MLSS is 4,500 mg/l
1. 72
2. 8.6
3. 138
4. 170
How many gallons of WAS should be removed if a 10 day SRT is the desired target (using all zones)?
· Two (2) Complete Bardenpho Trains:
Each Fermentation Tank is 119 ft. long, 43 ft. wide, and 15 ft. deep
Each 1st Anoxic Tank is 119 ft. long, 38 ft. wide, and 15 ft. deep
Each Aeration Tank has four (4) Passes, Each 125 ft. long, 25 ft. wide,
and 15 ft. deep
Each 2nd Anoxic Tank is 119 ft. long, 60 ft. wide, and 15 ft. deep
Each Reaeration Tank is 119 ft. long, 20 ft. wide, and 15 ft. deep
· WAS Concentration is 1.0% Total Solids
· WAS is 70% Volatile
· Aeration MLSS is 4,500 mg/l
1. 236,563 gpd
2. 198,875 gpd
3. 159,840 gpd
4. 319,693 gpd
What is the detention time in the aeration tanks? (not including RAS flow)
• Each Aeration Tank has four (4) Passes, Each 125 ft. long, 25 ft. wide, and 15 ft. deep
• Influent Flow is 10.5 mgd
1. 16.2 hours
2. 10.9 hours
3. 6.4 hours
4. 4.0 hours
What is the total length of weir for the secondary clarifiers?
• Four (4) Secondary Clarifiers, Each @ 120 ft. Diameter and 14 ft. Deep
1. 1,507 feet
2. 912 feet
3. 377 feet
4. 1,885 feet
Given the OP data, inlet and outlet of the fermentation tanks, does this indicate good operational performance?
• Fermentation Effluent OP is 20.5 mg/l
• Inlet OP is 8.0 mg/l
1. No, the OP is too high in the fermentation tank outlet
2. Yes, the OP should be 2 to 3 times the concentration of the tank inlet
3. The fermentation tank is not designed to release phosphorus as a conditioning process
4. There is not enough data to evaluate the efficiency of the fermentation tanks
How much alkalinity was consumed, using the standard 7.2 lbs of alkalinity consumed per lb of ammonia converted, given the effluent NH₃ value in the data?
· Effluent NH₃ is 0.1 mg/l
· Influent Flow is 10.5 mgd
· Influent NH₃ is 19 mg/l
1. 1,196 lbs
2. 916 lbs
3. 11,916 lbs
4. 12,655 lbs
Is the secondary clarifier calculated weir overflow rate acceptable, given the acceptable design is between 5,000 to 15,000 gpd/ft?
· Four (4) Secondary Clarifiers, Each @ 120 ft. Diameter and 14 ft. Deep
· Influent Flow is 10.5 mgd
1. Yes, it is lower than acceptable design values
2. No, it is higher than acceptable design values
3. There is not enough data to calculate the weir overflow rate
4. Weir overflow rate is not a parameter for secondary clarifiers
With all of the data and results for this plant, is the F/M ratio within an acceptable range?
· Aeration MLSS is 4,500 mg/l
· F/M ratio is 0.13
· MCRT is 20 days
1. Yes
2. No
3. The effluent quality is very poor
4. Both "b & c"
With all of the data and results for this plant, are the secondary clarifiers being overloaded?
· SLR is 14 ppd/ft2
· SSR is 232 gpd/ft2
· WOR is 7,000 gpd/ft
1. Yes
2. No
3. The effluent quality is very poor
4. There is not enough data to calculate clarifier loading rates
What action should be considered if "sloughing" from the trickling filter creates problems in the downstream processes?
1. Bypass the trickling filter
2. Dose the trickling filter media with HTH
3. Decrease the recirculation rate
4. Reduce the speed of the distribution arm
What are psychoda?
1. Organisms that cause sludge bulking
2. A type of red worm that grow on trickling filter media
3. Nitrifying bacteria found in sand filters
4. Small flies often found on trickling filters
Which time of day will generally produce the highest D.O. in an unaerated stabilization pond?
1. 12 midnight
2. 9 p.m.
3. 4 a.m.
4. 9 a.m.
What type of trickling filter would be more likely to receive 15 million gallons per acres per day?
1. Low rate
2. Polishing filter
3. Second stage filter
4. High rate
What action should be considered to control filter flies?
1. Take the filter out of service
2. Reduce the inlet flow rate
3. Flood the filter
4. Filter flies are never a problem
What could be the cause of an entire trickling filter media turning brown, with the exception of strips of green?
1. The recirculation rate is too high
2. The distribution arm stopped rotating
3. The media is not sloughing enough
4. The total flow rate to the filter is too high
Given the following data, what is the volume of this pond in acre-feet?
• Influent flow is 500 gpm
• Pond depth is 3 feet
• Pond detention time is 30 days
1. 0.15 acre-feet
2. 33.1 acre-feet
3. 120.3 acre-feet
4. 66.3 acre-feet
Where does nitrification primarily occur?
1. Anoxic
2. Fermentation
3. Aerobic
4. Anaerobic
Which group of bacteria are responsible for converting NO₂ to NO₃?
1. Heterotrophic
2. Nitrosomonas
3. Nitrobacter
4. Fermenters
Which group of bacteria can be facultative and are responsible for CBOD₅ removal and denitrification in the activated sludge process?
1. Heterotrophic
2. Nitrosomonas
3. Autotrophic
4. Fermenters
Which adjustment will normally improve denitrification in an aeration tank?
1. Increase the air supply
2. Increase the D.O.
3. Decrease the D.O.
4. Shut off the RAS
What happens to the activity rate of activated sludge microorganisms as the temperature increases by 10^oC?
1. It triples
2. It doubles
3. It remains the same
4. It is cut in half
Which adjustment may be best if the OP level entering a BNR secondary clarifier is acceptable, but the OP level in the clarifier effluent is too high?
1. Reduce the RAS rate and increase the SRT
2. Increase the RAS rate and decrease the SRT
3. Increase the MCRT
4. Reduce the reaeration D.O.
Which group of bacteria are responsible for converting NH₃to NO₂?
1. Heterotrophic
2. Nitrosomonas
3. Nitrobacter
4. Fermenters
Which adjustment may best solve the problem of a high ammonia level in the aeration effluent?
1. Increase the flow rate
2. Decrease the aeration D.O.
3. Place another secondary clarifier into service
4. Increase the aeration air supply
Given the following data, what level of TKN has been removed in this BNR plant?
• Influent TKN is 25.5 mg/l
• Effluent TKN is 1.5 mg/l
• Biology has taken-up 2.0 mg/l TKN
1. 24.0 mg/l
2. 22.0 mg/l
3. 26.0 mg/l
4. 38.25 mg/l
What activated sludge process alternates biological environments (by altering equipment), from aerobic to anoxic in the same reactor tank?
1. Bardenpho
2. Extended aeration
3. Sequence batch reactor
4. Pure oxygen reactor
What is the advanced stage of activated sludge called when bacteria oxidize their own cell mass?
1. Log growth
2. Declining growth
3. Cathodic protection
4. Endogenous respiration
What is an unacceptable range of TSS in the liquid overflow of a gravity thickener?
1. 1 to 3 mg/l
2. 5 to 15 mg/l
3. Above 100 mg/l
4. 20 to 30 mg/l
Given the following data, what is the depth of the cone, from the SWD to the bottom of the cone?
• Gravity Thickener is 50 Feet Diameter
• Sludge Blanket Depth is 3 Feet
• Floor Slope is 2:12
• Sludge Removed is 50,000 gpd
1. 2.08 feet
2. 1.02 feet
3. 6.14 feet
4. 4.17 feet
What is the cost of polymer used, in $ per dry ton processed, given the following data?
• Total sludge feed to the GBT is 76,750 gpd
• Feed sludge concentration is 0.75%
• Total polymer used is 10 gpd
• Polymer specific gravity is 1.03
• Polymer cost is $1.02 per pound
1. $45.24 / dt
2. $15.50 / dt
3. $36.51 / dt
4. $35.44 / dt
Given the following data: ($36.51 polymer per dry ton of sludge processed), is this an acceptable cost of polymer usage for a GBT?
1. Yes, very reasonable
2. No, it is too high
3. There is not enough data to calculate this parameter
4. This piece of information is not relevant to GBT operation
Which action will typically allow the float sludge to become thicker in the DAF process?
1. Increase the sludge feed rate
2. Decrease the recycle water rate
3. Decrease the top skimmer speed
4. Increase the top skimmer speed
Increasing the air saturation into the recycle stream can be accomplished two ways. What is one of the methods?
1. Increasing the polymer dosage
2. Decreasing the skimmer speed/frequency
3. Shutting off the pressurization pump
4. Increasing the amount of air into the pressurization tank
What may be the cause of an excessively deep bottom sludge blanket in a DAF unit?
1. The bottom sludge removal rate and/or frequency is too short
2. The solids loading rate is too low
3. The air to solids ratio is too high
4. A deep bottom sludge blanket does not indicate a problem
Which function other than sludge thickening can a centrifuge perform?
1. Secondary clarification
2. Sludge dewatering
3. Sludge stabilization
4. Conventional activated sludge
Given the following data, how many lbs/day of centrate will this centrifuge produce?
• Sludge Feed Rate is 250 gpm
• Sludge Feed Solids Concentration is 1.5% TS
• Centrate is 95% of Sludge Feed Rate
• Centrate Solids Content is 50 mg/l
• Centrifuge Operating Time is 16 hrs/day
1. 150 lbs/day
2. 143 lbs/day
3. 45,036 lbs/day
4. 95 lbs/day
Which component is most responsible for economical operation of a centrifuge?
1. Scroll
2. Drive
3. Bowl
4. Back drive
Which adjustment will normally increase the size of floc particles exiting an in-line venturi mixer?
1. Open the venturi mixer
2. Close the venturi mixer
3. Place a second venturi mixer into service
4. The venturi mixer has nothing to do with floc size
What device is used to turn over gravity sludge and create clean spaces on the belt (of a gravity belt thickener or belt filter press) to promote improved drainage?
1. Retention vessel
2. Venturi mixer
3. Chicane
4. Drive unit
Given the following data, what is the solids loading rate of this DAF unit?
• DAF tank is 80 feet long, 16 feet wide, and 12 feet deep
• Sludge feed rate 55 gpm for 750 mins/day
• Sludge feed concentration is 8,000 mg/l
1. 1.2 lbs/day/ft²
2. 3.6 lbs/day/ft²
3. 0.46 lbs/day/ft²
4. 2.1 lbs/day/f^t2
What does it mean when the DAF process has a slow floc time accompanied with a normal rise time?
1. Too much polymer but not enough air
2. Not enough polymer but the proper amount of air
3. Not enough polymer and not enough air
4. The air compressor has been off for several hours
What is the HRT in days of an aerobic digester given the following data:
• 75 ft. diameter tank
• 20 ft. deep
• TWAS feed 15,500 gpd
• Tank depth averaged 85% full during the calculation period
1. 62.6 days
2. 31.3 days
3. 23.5 days
4. 36.2 days
What is the Specific Oxygen Utilization Rate (SOUR) in an aerobic digester, given the following data?
• OUR test starting D.O. is 7.2 mg/l
• OUR test ending D.O. is 4.0 mg/l
• OUR test time is 10 minutes
• Digested sludge total solids concentration is 1.75%
1. 2.1 mg/hr/gm TS
2. 1.1 mg/hr/gm TS
3. 1.6 mg/hr/gm TS
4. 0.1 mg/hr/gm TS
Given the following data, and using the VanKleek formula, what is the percent volatile solids reduction in this anaerobic digester?
• Feed Sludge Total Solids = 3.4%
• Feed Sludge Volatile Solids = 2.7%
• Digested Sludge Out Total Solids = 2.4%
• Digested Sludge Out Volatile Solids = 1.7%
1. 40.1%
2. 37.1%
3. 34.5%
4. 47.1%
Which digester, in a two-stage anaerobic digestion process, is normally not mixed and/or heated?
1. Primary digester
2. Secondary digester
3. Neither are normally mixed or heated
4. Both are normally mixed and heated
Given the following data, what is the capacity of this digester?
• Digester tank diameter is 75 feet
• Digester depth is 24 feet to overflow
• Digester sludge feed rate is 125 gpm for 8 hrs/day
1. 1,125,147 gals
2. 792,693 gals
3. 3,170,772 gals
4. 157,045 gals
Given the following data, how much gas is being produced per pound of volatile solids destroyed in this anaerobic digester?
• Gas production 200,575 cf/day
• Sludge feed volume is 125,000 gpd
• Sludge feed total solids is 3.2% and the VS content is 81%
• Digested sludge removal volume is 122,000 gpd
• Digested sludge total solids is 2.3% and the VS content is 73%
1. 2.0 cf gas per lb VS destroyed
2. 0.049 cf gas per lb VS destroyed
3. 20.2 cf gas per lb VS destroyed
4. 18.4 cf gas per lb VS destroyed
Given the following data, what is the annual budget for lime in this plant?
• Lime dose rate is 4.5% per wet ton of sludge
• Sludge volume (based on dry weight) is 28,690 lbs/day
• Sludge cake is 18% TS
• Lime cost is $120.00 per ton delivered
• Sludge is processed every day of the year
1. $150,023
2. $245,345
3. $28,274
4. $157,067
What does the following formula represent?

OUR, mg/l/hr ÷ TS, gm/l = mg/hr/gm
1. Oxygen Uptake Rate
2. SOUR
3. SVI
4. Fecal coliform
Which process modifications may help resolve a condition of massive white foam and low pH in an aerobic digester?
1. Increase the sludge feed rate
2. Increase the air supply and increase the D.O.
3. Decrease the digester SRT
4. Decrease the air supply and decrease the D.O.
If an SOUR test performed on aerobically digested sludge is 1.1 mg/hr/gm TS, does this digester meet EPA's vector attraction reduction regulation for Class B residuals?
1. Yes
2. No
3. Not enough data to answer this question
4. This requirement dose not exist
What is a typical range for gas production in a properly operated anaerobic digestion process?
1. 1 to 2 ft³ per lb VS reduced
2. 5 to 7 ft³ per lb VS reduced
3. 11 to 20 ft³ per lb VS reduced
4. 40 to 60 ft³ per lb VS reduced
What are the two (2) reaction forming stages of anaerobic digestion?
1. Foam and oxygen
2. Acid and methane
3. Volatile solids and total solids
4. Nitrogen and methanol
If a volatile solids reduction calculation for an anaerobic digestion process is 37%, does this digester meet EPA's vector attraction reduction regulation for Class B residuals?
1. Yes
2. No
3. Not enough data to answer this question
4. This requirement dose not exist
What could be the cause of a "stuck" or "sour" digester?
1. High acid production
2. High alkalinity in the sludge
3. Sludge feed rate too low
4. Sludge temperature swings less than 1°F per day
Given the following data, what is the volatile solids loading rate in this anaerobic digester?
• Digester tank diameter is 75 feet
• Digester depth is 24 feet to overflow
• Digester sludge feed rate is 125 gpm for 8 hrs/day
• Sludge feed total solids concentration is 3.2%
• Sludge feed volatile solids concentration is 2.6%
1. 0.12 lbs per day VS per ft³
2. 1.2 lbs per day VS per ft³
3. 0.15 lbs per day VS per ft³
4. 1.5 lbs per day VS per ft³
Given the following data, how long would it take to fill this sand drying bed?
• Drying bed is 125 feet long, 25 feet wide, and fill to depth of 18 inches
• Fill pump is 124 gpm
1. 383 mins
2. 56 hours
3. 4.7 hours
4. 158 mins
What type of drying bed uses negative pressure to draw water through the bed’s media?
1. Cone bed
2. High pressure bed
3. Vacuum assisted bed
4. Gravity bed
Which chemicals are most commonly used to condition sludge being applied to a vacuum filter?
1. Bleach & Alum
2. Caustic & Ferric
3. Ferric Chloride & Lime
4. Lime & Bleach
Which is the only adjustment that will result in the belt filter press discharging more pounds of solids in the cake each hour of operation?
1. Increase the belt speed
2. Increase the sludge feed rate
3. Decrease the polymer feed rate
4. Decrease the pressure in the shearing zone
What is the primary function of polymer conditioning in the belt filter press process?
1. To decrease solids content
2. To promote rapid water release in the gravity section
3. To sterilize the microorganisms
4. To disinfect the sludge particles
What may be the result if the belt speed is too fast on a belt filter press?
1. The floc size may be too small
2. Gravity filtration will be very good
3. The cake solids may be too low
4. The cake solids will be very high
What is a potential problem if too much polymer is used in a belt filter press?
1. The belts may blind
2. The cost of operation will decrease
3. The filtrate quality will be too low in solids
4. The cake solids concentration may be too high
What does this formula represent?
lbs/day sludge feed - lbs/day sidestream ÷ lbs/day sludge feed x 100
1. Polymer dosage rate
2. Percent capture efficiency
3. Throughput production
4. Filtrate to feed ratio
What is the detention time of a chlorine contact chamber that is 100 feet long, 25 feet wide, 10 feet deep, and has a plant flow rate of 5.5 mgd?
1. About 2 hours
2. About 76 minutes
3. About 49 minutes
4. About 15 minutes
What type of chlorine residual is attained after the breakpoint is achieved?
1. Combined
2. Total
3. Free
4. Mono
What is the ratio of liquid chlorine when it expands to chlorine gas?
1. About 8.34 volumes
2. About 460 volumes
3. About 7.48 volumes
4. About 49.3 volumes
Given the following data, what should be the annual chlorine budget?
• Plant Flow = 1.5 mgd
• Preliminary Treatment Chlorine Dosage = 3.5 mg/l
• RAS System Dosage = 1.25 mg/l
• RAS to Q Ratio = 100%
• Effluent Chlorine Dosage = 7.2 mg/l
• Chlorine Cost = $0.25 per Pound
1. $25,564
2. $35,245
3. $14,789
4. $13,641
How does the UV system function in regard to disinfection of the final effluent?
1. The ultraviolet reduces the BOD₅ level
2. The ultraviolet radiation is absorbed by microorganisms and damages the genetic makeup of the organism preventing their further reproduction
3. The UV system promotes high growth rate of microorganisms and causes them to reach the death cycle quicker
4. The UV system increases the CBOD₅ value
What action should never be performed around a UV system?
1. Eating
2. Looking into the lamps without eye protection
3. Plugging a UV unit into a grounded electrical outlet
4. Collecting samples
Which effluent quality condition may cause the most problems with the UV disinfection process?
1. High NH₃
2. High NO₃
3. High NO₂
4. High TSS
What other supply, other than air, can be designed for application to an air feed ozone generator?
1. Pure nitrogen
2. Pure oxygen
3. Argon
4. Carbon dioxide
What will happen to chlorine residual go when ammonia in the effluent goes up?
1. Chlorine residual will increase if the chlorine feed rate is increased
2. Chlorine residual will increase if the chlorine feed rate is decreased
3. Chlorine residual will increase if the chlorine feed rate is shut off
4. Ammonia does not affect chlorine residual
What is created when chlorine reacts with ammonia in the effluent stream?
1. Chloramines
2. Free residual
3. Di-chloramines
4. Tri-chloramines
What action should never be performed with chlorine?
1. Spray water on a leaking container of chlorine
2. Feed 1 atmosphere gas through PVC pipes
3. Change chlorine containers using SCBA
4. Handle chlorinated effluent with gloves
Which chemical is more commonly used to dechlorinate chlorinated effluent?
1. Sodium hypochlorite
2. Bleach
3. Sulfur dioxide
4. Ferric chloride
What is the weight relationship of chlorine liquid as compared to water?
1. Water weighs more than liquid chlorine
2. Liquid chlorine weighs 2.5 times more than water
3. Water weighs 1.5 times more than liquid chlorine
4. Liquid chlorine weighs 1.5 times more than water
What are the two types of gaseous poisoning with chlorine called?
1. Vapor and pellets
2. Dry and wet
3. Mild and extreme
4. Coughing and choking
When a chlorine leak is identified, what color will it turn?
1. Yellow
2. White
3. Black
4. Green
What is the chemical formula for sulfur dioxide?
1. SO₄
2. O₂
3. CO₂
4. SO₂
What is the chemical formula for ozone?
1. O₄
2. O₂
3. CO₂
4. O₃
What is the theoretical horsepower required to operate a 2.5 mgd pump against a head of 65 feet?
1. 28.5 HP
2. 35.2 HP
3. 45.3 HP
4. 12.8 HP
What is the sum of the static head, friction head, headloss, and velocity head in a pump and pipe system called?
1. NPSH
2. Dynamic
3. TDH
4. PSIA
What is the total head on a pump if the inlet pressure reading is 2.5 psi, and the outlet pressure gauge reads 15 psi?
1. 12.50 feet
2. 28.87 feet
3. 40.42 feet
4. 35.47 feet
What is the electrical system called that prevents corrosion on steel surfaces in contact with water or soil?
1. Hammer
2. Short circuit
3. Cathodic protection
4. Oscillator protector
Which is not a positive displacement pump?
1. Rotary lobe
2. Recessed impeller
3. Progressive cavity
4. Hydraulic diaphragm
What is the main purpose of greasing an anti-friction bearing?
1. To stabilize friction
2. To comply with warranty
3. To increase operating temperature
4. To protect steel from corrosion
Given the following data, what is the total revenue collected annually from the industrial contributors?
• Total plant flow is 2.55 mgd
• Residential connections = 82% of the total flow
• Industrial sewer charge is $3.50 per 1,000 gallons
1. $1,606 per year
2. $586,372 per year
3. $293,186 per year
4. $2,671,252 per year
What is the term that describes the legal right to use the property of others for a specific purpose, such as installing or maintaining a sewer line?
1. Domain
2. Easement
3. Force main
4. Confined space
What should be budgeted as a total delivery cost for eight (8) valves if one (1) valve costs $537.99. The valves are shipped according to weight, with each valve weighing 104 lbs, at the rate of $1.50 per lb?
1. $4,303.92
2. $1,249.00
3. $6,551.92
4. $5,551.92
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 is the total annual budget for sludge disposal in this treatment plant?
• $0.035 per gallon disposal fee
• $8.25 per hour for the driver
• $0.95 per mile transportation costs
• 30 minutes to load 6,000 gals
• 45 minutes to unload 6,000 gals and wash the truck
• The disposal site is 25 miles from the plant
• The travel time is 45 minutes round trip
• 7,671 gpd sludge disposed with on-site sludge storage
1. $97,997 per year
2. $11,588 per year
3. $127,863 per year
4. $145,183 per year
Given the following data, what is the annual budget for sulfur dioxide in a facility?
• Plant flow rate is 1.5 mgd
• Effluent chlorine residual is 2.5 mg/l
• Sulfur dioxide to chlorine feed ratio is 1.25:1
• Sulfur dioxide costs $0.35 per pound
1. $5,327 per year
2. $4,994 per year
3. $1,998 per year
4. $2,245 per year
Given the following data, what is the equivalent percent total solids?
• 10 ml of sample
• Tare weight of filter is 1.8873 grams
• Final weight of filter after drying is 2.2255 grams
1. 2.2%
2. 1.3%
3. 3.4%
4. 4.3%
What piece of equipment is not used in the volatile solids test?
1. Muffle furnace
2. Desiccator
3. Analytical balance
4. Test tubes
Which two lab tests, when added together, make-up TKN?
1. TN & Org-N
2. SON & TN
3. NO₃ & NH₃
4. NH₃& Org-N
What is the CBOD₅concentration, given the following data?
• BOD bottle volume is 300 ml
• Sample volume is 15.0 ml
• Initial D.O. is 8.0 mg/l
• Final D.O. after incubation is 4.0 mg/l
1. 20 mg/l
2. 80 mg/l
3. 60 mg/l
4. 96 mg/l
Given the following data, what is the TSS concentration in mg/l?
• 50 ml of sample
• Tare weight of dish is 11.8873 grams
• Final weight of dish 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 a molecule called when it has a positive electrical charge?
1. Anion
2. Non-ion
3. Cation
4. Electron
Given the following data, how many total gallons are in this digester? (including the cone)
• 25 ft diameter
• 15 ft deep
• 3.12 ft cone depth
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 final effluent TSS value if the plant influent TSS is 225 mg/l, and the TSS percent removal is 97%?
1. 7.65 mg/l
2. 3 mg/l
3. 6.75 mg/l
4. 3.375 mg/l
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 12 feet of static water level?
1. About 5.2 psi
2. About 27.7 psi
3. About 12.0 psi
4. About 4.3 psi
What will be the volume of a tank if the flow entering is 1 mgd and the detention time is 3.5 hours?
1. 583,000 gals
2. 1.2 mg
3. 145,833 gals
4. 312,500 gals
What is the daily volume of WAS to be removed in a plant with 16,680 pounds of MLSS under aeration, a desired SRT of 25 days, and a WAS concentration of 15,000 mg/l?
1. 12,356 gals/day
2. 7,439 gals/day
3. 3,335 gals/day
4. 5,333 gals/day
What is the formula to calculate the weight of a cubic foot of water?
1. 7.48 gal/ft³ x 3.14
2. 8.34 lbs/gal ÷ 7.48 gal/ft³
3. 7.48 gal/ft³ x 8.34 lbs/gal
4. 92.4 cfm/mgd x 8.34 lbs/gal
What is the percent removal of solids in a gravity thickener, given the following data?
• 20 gpm sludge feed rate
• 1.12% sludge feed concentration
• 150 mg/l liquid overflow from the thickener
1. 99.9%
2. 98.7%
3. 86.6%
4. 97.5%
Which formula is used to calculate the circumference of a circular tank?
1. π r²
2. π d²
3. 0.785 d²
4. π d
Given the following data, how many gallons of sludge is in the cone of this anaerobic digester?
• 25 ft diameter
• 15 ft deep
• 3.12 ft cone depth
1. About 2,432 gallons
2. About 5,048 gallons
3. About 3,817 gallons
4. About 3,217 gallons
What is the average velocity, in ft/s, in a 12-inch diameter pipeline carrying a daily flow of 2.5 mgd?
1. 4.90 ft/s
2. 3.86 ft/s
3. 0.21 ft/s
4. 5.80 ft/s
What is the flow rate in an 8-inch pipe if the velocity is about 3.1 ft/s?
1. 500 gpm
2. 0.70 mgd
3. 250 gpm
4. 1.2 mgd
What is the volume of sludge in 14 inches of a digester with a diameter of 75 feet?
1. 33,029 gallons
2. 3,752 gallons
3. 20,588 gallons
4. 38,545 gallons
Given the following data, what is the SRT in this activated sludge plant?
• 12 mgd flow
• 150 mg/l influent CBOD5
• 2 mg/l effluent TSS
• Four (4) aeration tanks, each @ 200 feet long, 40 feet wide, and 15 feet deep
• 2,750 mg/l MLSS
• 6,250 mg/l WAS
• WAS volume is 2.5% of influent flow
1. 1.3 days
2. 2.6 days
3. 5.2 days
4. 10.4 days
Given the following data, what is the velocity (ft/min) in this channel?
• Flow rate is 1,500 gpm
• The channel is 6 feet wide with a depth of flow of 15 inches
1. About 27 ft/min
2. About 17 ft/min
3. About 35 ft/min
4. About 13 ft/min
What chemical is typically used to neutralize leaking chlorine gas?
1. Hydrate lime
2. Sodium hydroxide
3. Bleach
4. Polymer
What action is appropriate while wearing disposal gloves?
1. Smoke
2. Scratch your face
3. Collect samples
4. Shake hands with others
What procedure should never be performed while entering a manhole that has been classified as a permit confined space?
1. Wear a body harness
2. Complete a confined space entry permit
3. Test the air with a gas detector
4. Enter without an attendant
Which respiratory protection device is not acceptable for use in a confined space?
1. Supplied air respirator
2. Self contained breathing apparatus (SCBA)
3. Paper filter mask
4. Positive pressure escape pack
Which two (2) chemicals are of primary concern, as related to OSHA’s Process Safety Management Program?
1. Polymer & sodium hypochlorite
2. Chlorine gas & alum
3. Sodium hydroxide & sulfur dioxide
4. Chlorine gas & sulfur dioxide
What is the human threshold of hydrogen sulfide gas?
1. 0.0005 mg/l
2. 0.05 mg/l
3. 10 mg/l
4. 0.5 mg/l
What is the best tool for ensuring safe working conditions in a confined space?
1. Steel-toe shoes
2. Hard hat
3. Confined space entry permit
4. Goggles
What excavation depth, according to OSHA, is classified as a confined space?
1. 6 feet
2. 4 feet
3. 5 feet
4. 10 feet
Which noise level in the workplace does OSHA require implementation of a hearing protection program?
1. 120 decibels, 2 hour, time weighted average
2. 90 decibels, 16 hours, time weighted average
3. 85 decibels, 8 hour, time weighted average
4. 70 decibels, 4 hour, time weighted average

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Wastewater Operator Study Guide Module 3 ... Practice Quiz ... Happy Studying!Return to the Quiz Home Page by Clicking the Upper Right "x" on Your Browser

Wastewater Operator Study Guide Module 3 ... Practice Quiz ... Happy Studying!
Return to the Quiz Home Page by Clicking the Upper Right "x" on Your Browser