Wastewater Treatment Overview

Excessive solids appear to be plugging or “blinding” the bar screen. Which are possible reasons for this problem?
1. Hydraulic overload or solids overload
2. Not enough flow or not enough solids
3. System being bypass
4. All of the above
Recirculation is incorporated into the design of an EQ process for what reason?
1. Reduce the size and volume of suspended solids in the tank.
2. Improve mixing of the contents.
3. Provide more precision in flow monitoring.
4. Provide additional opportunity to cool the wastewater.
The prime purpose of a neutralization process is to optimize chemical reactions, promote biological activity, prevent corrosion and:
1. Cause resin beads to settle better in the primary clarifier.
2. Cause grease and oil to float on the primary clarifier.
3. Neutralize acid and alkaline wastewater to within discharge limits.
4. Increase the conductivity of the wastewater
What is an acidic pH range?
1. 7 to 14
2. 8 to 12
3. 0 to 6.9
4. 7.0
What are three chemicals that can be used to raise the pH level in water?
1. Sodium hydroxide, lime, and soda ash.
2. Sulfamic acid, nitric acid, and muriatic acid, cationic.
3. Anionic and non-ionic polymers.
4. Chlorine, sodium bisulfite, and calcium hypochlorite (HTH).
Which microorganisms are most responsible for stabilization of organic material?
1. Rotifers
2. Stalk Ciliates
3. Bacteria
4. Worms
Which indicator organisms will be more dominant when the SRT is low and the sludge is young?
1. Rotifers
2. Stalk Ciliates
3. Water Bears
4. Free Swimming Ciliates
Which conditions will typically allow filamentous bacteria to grow and become dominant in activated sludge?
1. Low D.O. and high F/M
2. High D.O. and low F/M
3. High D.O. and high F/M
4. Low D.O. and low F/M
Which is an aerobic process where certain groups of microorganisms convert Ammonia-N into Nitrite-N and then to Nitrate-N?
1. Fermentation
2. Anoxic
3. Anaerobic
4. Nitrification
What may be the cause of septic odors in the RAS stream?
1. Aeration D.O. too high
2. WAS rate too high
3. Low H₂S values in the influent
4. Aeration D.O. too low
What may be the most probable cause for slow settling MLSS?
1. High RAS rate
2. Filamentous bacterial growth
3. Balanced F/M ratio
4. Low sludge blanket
What may be the best adjustment to make if pin floc in the clarifier is increasing TSS in the effluent to unacceptable levels?
1. Increase the SRT
2. Decrease the F/M ratio
3. Decrease the SRT
4. Decrease the WAS rate
What is the reaction called when some molecules are broken down and others are formed?
1. Hydrolysis
2. Metabolism
3. Reproductions
4. Fission
During aerobic respiration in which a carbohydrate (sugar) is broken down, what end products are released?
1. Nitrogen, water, and oxygen
2. Methane, carbon dioxide, and hydrogen
3. Carbon dioxide, water, and hydrogen sulfide
4. Carbon dioxide, water, and energy
When BOD is present in excess of the amount which can be assimilated by the microorganisms, what growth phase does this most likely represent?
1. Logarithmic growth
2. Endogenous respiration
3. Declining growth
4. Lag phase
What are organisms called that thrive at high temperatures?
1. Psychrophilic
2. Mesophilic
3. Thermophilic
4. Coliforms
Ciliates are important indicator organisms in activated sludge operations. This is because they:
1. Are associated with flocculent biomass and good treatment.
2. Consume most of the BOD load
3. Make sludge settle rapidly in the secondary clarifier.
4. Indicate the sludge is very young and dispersed.
A sample of secondary clarifier ___________ is collected for measuring turbidity.
1. Sludge
2. Scum
3. Floc
4. Effluent
A “rise time” test is done in a settleometer. Rising sludge mimics what process in the clarifier?
1. Nitrification
2. Denitrification
3. Flocculation
4. Breakpoint chlorination
Briefly describe the significance and use of the Oxygen Uptake Rate test.
1. Measures the mg/l of oxygen utilized by the bacteria per hour of time.
2. Measures the settling quality of MLSS.
3. Measures the concentration of the activated sludge
4. Measures the number of bugs in the system.
Secondary clarifiers are used to:
1. Increase sludge digestion
2. Allow septic conditions to develop
3. Provide a home for organisms
4. Remove solids generated by biological processes
Sludge volume index (SVI) is measured on:
1. Aeration tank mixed liquor
2. Settled sludge
3. Primary supernatant
4. Chlorine tank effluent
Under which of the following circumstances should sludge wasting always be increased?
1. Mixed liquor settles too slowly
2. Large billows of white foam start forming on the aeration tank surface
3. A dark brown, scummy foam appears on the aeration tank surface.
4. None of the above.
The prime purpose of a gravity filtration system is to remove
1. BOD
2. COD
3. Nitrogen and acrylonitrile
4. Suspended solids
Pulsing is described as an “air mix agitation” cycle that occurs periodically during a filtration
cycle. What typically activates an air scour cycle?
1. When the filter level falls
2. When the filter level rises
3. When the backwash cycle is complete
4. Manually
The differential pressure between the levels above and below the filter media is referred to as:
1. Pulse differential
2. Head loss
3. Hydraulic loading rate
4. Air binding
The typical purpose and function of an activated carbon filtration system is to
1. Remove inorganic contaminants from water and wastewater
2. Absorb heavy metal compounds from water and wastewater
3. Remove organic contaminants from water and wastewater
4. All of the above
Adding powdered activated carbon to biological systems can:
1. Enhance the performance of the system
2. Adsorb lead, copper, chrome, and nickel contaminants
3. Improve the settling characteristics of the mixed liquor suspended solids
4. Help maintain the water in a neutral pH range
Which is not a purpose and function of a hypo-chlorinator system?
1. Control pathogenic organisms in wastewater
2. Control algae growths on tank walls or in filters
3. Control non-settling filamentous organisms in the activated sludge process
4. Disinfection of the plant influent
The presence of the hypochlorite and hypochlorous acid ions are measured in which of the following tests?
1. Chlorine demand
2. Free chlorine residual
3. Combined chlorine residual
4. Total chlorine residual
31. Solution piping and valves used in chlorination systems should be corrosion-resistant. The best choice of the following materials is:
1. Mild steel
2. Stainless steel
3. Copper lined fiberglass
4. PVC
Typically, where is the best location to obtain a sample to conduct a settleometer test?
1. Clarifier effluent
2. Aeration outlet MLSS
3. Belt press cake
4. Gravity thickener filtrate
As sludge age increases, what happens to Food-to-Microorganism Ratio?
1. Increases
2. Decreases
3. Stays the Same
4. Has no effect
The majority of BOD is consumed by
1. Amoebas
2. Bacteria
3. Ciliates
4. Flagellates
Typically, what may be added to the influent to stabilize high pH?
1. Acid
2. Base
3. Chlorine
4. Sodium hydroxide
Other than parts per million (ppm), what other units express the concentration by weight of a substance per unit volume?
1. Cubic centimeters; cc
2. Milliliters per gram; ml/gm
3. Milligrams per liter; mg/l
4. F/M ratio
What is the term that refers to the total suspended solids in an activated sludge aeration basin?
1. Sludge blanket
2. Mixed aerobic suspended solids (MASS)
3. Volatile solids percentage (VSP)
4. Mixed liquor suspended solids (MLSS)
What is the activity that brings fine particles into contact with each other by neutralizing their repellant electrical charge by using alum, ferric chloride, or lime?
1. Coagulation
2. Dechlorination
3. Oxidation
4. Particle reduction
How are belt filter presses typically used in a treatment plant?
1. They reduce the water content of sludge before disposal
2. They stabilize raw sludge so that it can be spread on land
3. They thicken sludge prior to return to the aeration basin
4. They disinfect sludge to be handled
What sidestreams are present in a typical belt filter press system?
1. Filtrate and sludge cake
2. Wash water and sludge feed
3. Filtrate and wash water
4. Sludge cake and sludge feed
The mechanical screening system is designed to:
1. Remove sanitary waste products flushed into the system.
2. Dampen flow characteristics to the equalization tank.
3. Strain out particles larger than the screen openings.
4. Strain out particles greater than .50 inches in size.
Components of a mechanical screen system, which should be monitored for breakdown, include:
1. carriage and cleaning rake
  
  knife gate to screen
  high level switch
  wiper assembly
2. motor and reducer screen drive
3. drain ball valve
4. All of the above
If the water level in the inlet side to a screen becomes too high due to clogging or excessive flow, a level switch will open an emergency bypass valve and close the inlet valve.
This response will occur when the screen controls are:
1. activated locally by the operator
2. in the HAND position.
3. in the AUTOMATIC position
4. in the off position
Flow to the screen which exceeds its design capacity will likely:
1. activate the high level switch, bypassing flow directly to an EQ tank.
2. be handled by the system for up to 8 hours.
3. trigger an audible alarm at the local control panel.
4. be recirculated to the influent sump.
What safety hazards that should be remembered before working around a mechanical screen?
1. Trips and falls
2. Exposure to explosive materials or gases
3. Electrical hazards from high voltage equipment.
4. All of the above
Excessive solids appear to be plugging or “blinding” the screen.
What is the possible reason for this problem?
1. Hydraulic overload or Solids overload
2. Not enough flow
3. Too much flow
4. None of the above

Wastewater Treatment Overview

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