Basic Wastewater Operator Practice Exam Class 3
3472 GPM
A WWTP flow is 5.0MGD, how many gallons per minute is this?
Representative and Sub-samples time spaced over 15 minutes apart
A composite sample must be?
The packing bolts or nuts on the packing gland are properly adjusted
A horizontal centrifugal pump has "rope" packing. When the pump is in operation, water slowly drips from the packing gland. What does this indicate?
Cross-connection by back siphonage
A local college has an outbreak of Giardia in the water system; a hose that was connected to a spigot was found in a grease trap, and that was determined to be where the bacteria entered the system. What is this an example of?
Increase recirculation
A trickling filter arm is moving slow. How do you speed it up?
Check/ replace the bulb in the indicator light
An equipment failure warning light did not turn on, but a failure was reported and repaired. What is the first thing the operator needs to do?
Unequal air distribution caused by a blown diffuser
An operator notices a portion of the aeration tank with large bubbles rising up. What is the most likely problem?
will decrease with an increase in discharge head
Assuming a constant suction head, the discharge of a centrifugal pump _______________________
0.68
Calculate F:M ratio GIVEN: Influent BOD5 = 290mg/l Influent Flow = 5.0MGD Aeration basin MLSS = 2650 mg/l Aeration basin volume = 0.8MG
24 days
Calculate SRT GIVEN: Mixed liquor suspended solids (MLSS) = 2400mg/l Aeration basin volume = 35,000 gallons = 0.0350 million gallons (MG) Waste activated sludge (WAS) concentration = 3500mg/l Waste activated sludge (WAS) flowrate = 0.001MGD
225
Calculate SVI GIVEN: 30 minute settling test = 1800ml in a 2000ml container MLSS: 4000mg/L
360mg/l
Calculate the BOD given the information: Initial DO: 8.3 Final DO: 5.9 Milliliters of sample used: 2
9090 lbs/day
Calculate the pounds per day of chemical dosage with a flow of 5MGD, dosing at a rate of 218 PPM.
0.123 MG
Calculate the total volume in million gallons of both tanks. GIVEN: Tank A = 20 ft. diameter, 35 ft. tall Tank B = 45 ft. long, 20 ft. wide, 6 ft. deep.
Heavier than air
Chlorine gas is what?
Disinfection
Chlorine is primarily used for what?
2-3 hours
Common hydraulic detention times for primary clarifiers range from?
Extended Aeration
Considering the layout and flow diagram for the complete treatment plant, oxidation ditch plants would be most similar to the following?
Typhoid fever, Dysentery, Cholera
Diseases potentially carried by wastewater include__________________.
By measuring the pump output
How do you calibrate a chemical feed pump?
Add acid to water slowly, while stirring to dissipate heat
How do you mix acid with water?
Slow down the belt
How does an operator improve the filter cake exiting on a belt press?
To prevent contamination of potable water systems
How is an air-gap device used?
Horizontal & Horizontal
How should a 1-ton chlorine cylinder be moved?
Flush with water
How should lime slurry lines be cleaned?
Rotten eggs
Hydrogen sulfide gives off an odor similar to what?
284ml
If you are collecting a manual flow proportional composite sample with the following flows, and you want to collect a total of 1000ml, how much sample would be needed for sample #4? Flow #1: 12367 Flow #2: 12452 Flow #3: 12511 Flow #4: 12612 Flow #5: 12710
Plug valve
If you have a lime slurry feed line, what is the best valve to use?
Old Sludge
If you notice a predominance of rotifers in your activated sludge sample while looking at it under a microscope, what does this indicate?
Settling in the clarifiers
If your activated sludge plant begins to nitrify, what conditions would you expect to decrease?
Flow running too slow through discs
In an RBC plant, the microscopic investigation revealed some amoebas and flagellates in the first set of discs; the second set showed free-swimming ciliates and some rotifers; and the third set had blood worms and nematodes. What is this an indication of?
Parshall Flume
Name a device that is used to measure the flow of wastewater...
Center of discharge line at ground level
Suction lift pressure is measured from the center line of the pump to _________________?
The alkalinity will decrease
The ammonia loading on a plant is increasing. What should the operator expect regarding the amount of alkalinity in the system?
Near the top
The highest concentration of algae growth in a facultative lagoon is usually observed where?
Decrease the lag time for pump operation by moving the floats closer together
The influent to the treatment plant is septic. It is determined that it is coming from a lift station upstream from the plant. What should the operator do?
PSI
The pressure against which a pump must operate is measured in terms of what?
22.5 mg/l
The primary effluent to a RBC system is 350 mg/l BOD. The primary unit removes 83%, the secondary unit removes 50%, and the final unit removes 25%. What is the BOD leaving the final unit of the RBC train?
On the tile underdrain system
The rock in a trickling filter is usually placed where?
Long, slow strokes
To prevent wear on a piston pump shaft, what kind of strokes should be made?
Water hammer
Valves should be closed slowly to avoid what?
Blockage in intake
What causes a centrifugal pump discharge pressure to increase and discharge quantity to decrease?
Sulfides
What causes a white slimy coating on an RBC filter?
blockage in discharge line
What causes reduction in pump discharge rate?
Production of Volatile Acids
What causes the pH to decrease during the anaerobic digestion process?
sulfur dioxide
What chemical is used for de-chlorination?
Water pressure
What factors control the throat size in a chlorinator?
Flush with cold water
What immediate first aid should be given for burns?
Amounts of solids in the sample
What information does a mixed liquor test provide?
Flush with cold water for 15 minutes
What is First-Aid for someone getting chlorine gas in their eyes?
Organic Nitrogen and Ammonia
What is Total Kjeldahl Nitrogen (TKN) comprised of?
A valve that is closed by the pressure of a fluid so that the fluid does not flow back in the direction it came from
What is a check valve?
Check Valve
What is a valve that allows water to flow in one direction only?
An organism that transfers disease or parasite from one to another
What is a vector?
Watch full cycle
What is normal daily maintenance for an automatic bar screen?
Impeller
What is one component of a centrifugal pump?
Excessive moisture
What is one of the most likely causes of electric motor failure?
The pressure on the suction side of the pump
What is suction lift?
Butterfly Valve
What is the best valve for throttling flow?
With a chemical absorbent
What is the best way to clean up a polymer spill?
H2SO4
What is the chemical formula for sulfuric acid?
H2S
What is the chemical symbol for Hydrogen sulfide?
In valve open; Out valve open
What is the correct valve position when starting a reciprocating pump?
Voltage
What is the force that can send current down the line when the breaker is off?
Containment and Cleanup
What is the main concern when a chemical spill occurs?
Increase wasting
What is the most appropriate method of reducing the F:M Ratio?
Increase wasting rate
What is the most appropriate method to decrease F:M ratio?
extended aeration
What is the most common type of Activated Sludge package plants?
Stalked ciliates
What is the predominant organism in a healthy Activated Sludge Treatment Plant?
As an inhibitor solution for the DO analysis using the APHA method
What is the purpose for adding Copper Sulfamic Acid?
To protect chemicals that are sensitive to light
What is the purpose of amber storage bottles?
To increase the digestion rate
What is the purpose of heating and mixing a primary anaerobic digester?
300ml
What is the standard volume for a BOD sample bottle?
Mitigation
What is the term used to refer to the action taken to prepare for an emergency?
Denitrification
What is the term used when bacteria convert nitrates and nitrites to nitrogen gas under anoxic conditions?
Nitrification
What is the term used when the nitrifiers convert the ammonia to nitrites and nitrates under aerobic conditions?
Sulfur and Hydrochloric acid are formed
What occurs to hydrogen sulfide when it reacts with chlorine?
diethyl-p-phenylene diamine or D.P.D.
What reagent is used to determine Chlorine residual?
Inspect the affected equipment to determine the cause
What should an operator do if a fuse continues to blow?
Increase the backwash frequency
What should an operator do when excess solids enter a media filter?
Decreased settling rate
What should an operator expect to occur when flow increases to the secondary clarifiers?
Waste more sludge
What should be done when the bio-reactor in an SBR plant is organically overloaded?
Fecal Coliform
What test is typically never performed on wastewater influent?
magnetic
What type of flow meters are used during normal operations of the sludge removal?
Polyvinyl Chloride (PVC)
What type of supply pipe is recommended for gaseous chlorine?
Clogged impeller
What would most likely cause a submersible pump to have an AMP reading that is above the optimum level?
In the middle, after all return flows have been well mixed
When collecting a sludge sample, where is the most representative sample location?
Bacteria
When organic wastes are discharged to receiving waters, what depletes oxygen?
Normal operation
When you install a new packing gland, you notice that there is a slow, steady stream of water coming out of the packing area. What is this an indication of?
2/3 the length of the converging wall measured back from the throat
Where in a Parshall Flume does an operator take a manual flow reading?
At floor level
Where should the exhaust from a chlorinator room be taken from?
Conventional
Which Activated Sludge process handles shock loads of high organic waste most effectively?
Methane
Which gas is produced in an anaerobic digester and can be used as fuel?
Stator
Which of the following are non-moving parts of a running motor?
NH3 (ammonia)
Which of the following can be analyzed using composite samples?
Oil & Grease
Which of the following can be analyzed using composite samples?
To keep valves from being submerged
Why are approved backflow devices installed above ground level?
To prevent wastewater in the discharge line from flowing back through the pump
Why are check valves used in conjunction with centrifugal pumps?
Broken clarifier drive
Your system has two clarifiers, with equal flow going to both. One of the clarifiers is operating fine with good clarity. The other is having pop-ups. What is the most likely cause?
766 lbs/day
Your system serves 2740 people and an industry contributes 300 lbs/day of BOD. How many pounds per day of BOD are received at your plant?
