Wastewater Treatment Concepts

What is considered to be a neutral pH?
1. 6.5
2. 14.0
3. 10.0
4. 7.0
Which is the physical process that follows an aeration tank?
1. Preliminary treatment
2. Tertiary treatment
3. Activated sludge process
4. Secondary clarification
Which gases may be found in sewer collection systems?
1. Explosive gases
2. Hydrogen sulfide
3. Methane
4. All of the above
What is the main cause of water seepage into a sanitary sewer?
1. Poor construction of the collection line, especially at pipe joints
2. Sewer line too deep
3. Sewer line diameter too small
4. Improper cycling of lift stations
What is a common spacing between the bars for a fine bar screen?
1. 2 inches
2. ¼ inch
3. 4 inches
4. 1 micron
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
What percentage of total suspended solids (TSS) is typically removed in a primary clarifier?
1. 25%
2. 100%
3. 50%
4. 85%
Associated with primary clarifier scum, what does FOG mean?
1. Fat Oil Grease
2. b. Full Organic Gold
3. c. Firm Oily Gate
4. d. Fat Old Guy
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 aeration foam may indicate a young sludge condition?
1. Black in color
2. Dark brown in color
3. White or very light in color
4. Very dark grey in color
Which chemical is typically used for conditioning the sludge feed applied to a gravity belt thickener process?
1. Lime
2. Polymer
3. Ferric chloride
4. Chlorine
12. What is the principle concept of the gravity belt thickener?
1. Dewaters through pressure shearing
2. Thickens through gravity drainage
3. Thickens through high speed spinning
4. Thickens through pressure filtration
Which test is better to use for process control of an anaerobic digestion process?
1. pH
2. Acid/alkalinity
3. Total solids
4. Scum blanket
What color should digested sludge be in a properly operated anaerobic digestion process?
1. Black
2. Grey
3. Green
4. Brown
What is the basic principle of a belt filter press?
1. To stabilize volatile solids
2. To destroy microorganisms
3. To increase the sludge volume
4. To remove water from a liquid/solids suspension
Which term is most related to vector attraction reduction in an aerobic digester?
1. Settleometer
2. Pathogen
3. SOUR
4. F/M
What form of chlorine comes in one-ton containers?
1. Gas from both valves
2. Liquid from both valves
3. Liquid from the top valve and gas from the bottom valve
4. Gas from the top valve and liquid from the bottom valve
What is the relationship of liquid chlorine to water?
1. Liquid chlorine is 1½ times lighter than water
2. Liquid chlorine is the same weight as water
3. Liquid chlorine is 1½ times heavier than water
4. Liquid chlorine is 2½ times heavier than water
What type of maintenance is performed on a piece of equipment after it breaks?
1. Corrective
2. Preventive
3. Quarterly
4. Emergency
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 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 type of solids are identified in a muffle furnace test?
1. Settleable
2. Suspended
3. Volatile
4. Dissolved
Which may be the better adjustment to make 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
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
What may be the cause if BOD₅ removal in a primary clarifier is less than 15%?
1. a. The plant is underloaded clarifier is normal
2. b. The detention time is too short
3. c. The detention time is too long
4. d. 15% BOD₅ removal from a primary
28. 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. Decrease RAS
4. Increase WAS
What adjustment may help if solids are rising in the secondary clarifier accompanied by large septic gas bubbles?
1. Increase aeration D.O.
2. b. Decrease RAS rate
3. c. Decrease WAS rate
4. d. Increase SRT
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 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
Where does nitrification primarily occur?
1. Anoxic
2. Fermentation
3. Aerobic
4. Anaerobic
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
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
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 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
What could be the cause of a "stuck" or "sour" digester?
1. High acid production
2. b. High alkalinity in the sludge
3. c. Sludge feed rate too low
4. d. Sludge temperature swings less than 1°F per day
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
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. Test the air with a gas detector
3. Complete a confined space entry permit
4. Enter without an attendant
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

Wastewater Treatment Concepts

Practice Quiz QuestionsBrought to you free of charge by RoyCEU.com

Practice Quiz Questions
Brought to you free of charge by RoyCEU.com