TEXAS WASTEWATER D 2026 TEST PAPER QUESTIONS
AND SOLUTIONS RATED A+
✔✔What are the different bacteria classifications? - ✔✔Shape, oxygen needs,
temperature, and metabolism
✔✔Types of ponds used in treatment are: - ✔✔- aerated (mechanic aeration to mix
oxygen, organics, and microorganisms)
- facultative (two zones of treatment - aerobic and anaerobic)
- anaerobic
- hyacinth
✔✔Wastewater ponds will effectively reduce ___ - ✔✔BOD and bacteria
✔✔The ideal orientation of a wastewater stabilization pond would be: - ✔✔parallel with
prevailing winds
✔✔What is the activated sludge process? - ✔✔Uses living organisms in an oxygen-rich
environment to remove organic wastes from wastewater
✔✔What is the oxygen rate in an activated sludge system? - ✔✔2-4
✔✔What is the purpose of Return Activated Sludge (RAS)? - ✔✔Pumps continuously
send RAS to the aeration tank, which reseeds the biological reaction in the aeration
tank and removes accumulating sludge from the clarifier
✔✔What is F/M? - ✔✔The ratio of the amount of food applied per day to the
microorganisms in the aeration tanks
✔✔What is Gould Sludge Age? - ✔✔How long, in days, a pound of solids stays in the
aerator
✔✔What is Mean Cell Residence Time? - ✔✔Estimates how long the living cells are
kept in the plant
✔✔What are the five important controls for activated sludge plants? - ✔✔- Dissolved
Oxygen
- Aerator solids levels
- Solids quality
- Rate of return sludge
- Wasting rate
✔✔What would be the cause of rising sludge and gas bubbles in the final clarifier? -
✔✔Denitrification
, ✔✔(This one is opposite)
A = Influent
B = Aeration Tank
C = Clarifier
D = Waste Activated Sludge
E = Return Activated Sludge - ✔✔What does A-F represent?
✔✔What is a trickling filter? - ✔✔A fixed film process where wastewater trickles over
media, usually rock or plastic. Wastes are then consumed by layers of bacteria,
protozoa, fungi, and other organisms that live on the media.
✔✔What are the five basic parts in a trickling filter? - ✔✔- Filter floor
- Underdrain system
- Walls
- Filter media
- Distribution arms
✔✔What is the material that sloughs off the trickling filter that settles in the clarifier? -
✔✔Humus sludge
✔✔What is super important about the distribution arms on a trickling filter? - ✔✔Orifices
or nozzles on the rotating arms should be inspected daily for clogging and cleaned if
necessary. There should be no trash or large debris through the filter.
✔✔How do Rotating Biological Contactors spin? - ✔✔Each unit is driven either by a
motor with a gear reducer or by air trapped in air cups
✔✔In Rotating Biological Contactors, what is the biological growth like? - ✔✔The entire
wetted surface area of the disc becomes covered by a 0.05-0.1 inch film of gray to
brown biological growth. It contains approximately 50,000 mg/L of solids
✔✔What can advanced treatment processes do that secondary treatment can't? -
✔✔Advanced treatment processes strive to provide a higher removal level of specific
compounds, suspended solids, and oxygen-demanding materials that cannot be
achieved through secondary treatment alone.
✔✔In advanced treatment processes, what is the most important factor affecting filter
performance? - ✔✔the quality of the secondary effluent being applied to the filter - low
in solids
✔✔In advanced treatment, a filtration process should remove about ____ of the TSS
applied - ✔✔70%-90%
AND SOLUTIONS RATED A+
✔✔What are the different bacteria classifications? - ✔✔Shape, oxygen needs,
temperature, and metabolism
✔✔Types of ponds used in treatment are: - ✔✔- aerated (mechanic aeration to mix
oxygen, organics, and microorganisms)
- facultative (two zones of treatment - aerobic and anaerobic)
- anaerobic
- hyacinth
✔✔Wastewater ponds will effectively reduce ___ - ✔✔BOD and bacteria
✔✔The ideal orientation of a wastewater stabilization pond would be: - ✔✔parallel with
prevailing winds
✔✔What is the activated sludge process? - ✔✔Uses living organisms in an oxygen-rich
environment to remove organic wastes from wastewater
✔✔What is the oxygen rate in an activated sludge system? - ✔✔2-4
✔✔What is the purpose of Return Activated Sludge (RAS)? - ✔✔Pumps continuously
send RAS to the aeration tank, which reseeds the biological reaction in the aeration
tank and removes accumulating sludge from the clarifier
✔✔What is F/M? - ✔✔The ratio of the amount of food applied per day to the
microorganisms in the aeration tanks
✔✔What is Gould Sludge Age? - ✔✔How long, in days, a pound of solids stays in the
aerator
✔✔What is Mean Cell Residence Time? - ✔✔Estimates how long the living cells are
kept in the plant
✔✔What are the five important controls for activated sludge plants? - ✔✔- Dissolved
Oxygen
- Aerator solids levels
- Solids quality
- Rate of return sludge
- Wasting rate
✔✔What would be the cause of rising sludge and gas bubbles in the final clarifier? -
✔✔Denitrification
, ✔✔(This one is opposite)
A = Influent
B = Aeration Tank
C = Clarifier
D = Waste Activated Sludge
E = Return Activated Sludge - ✔✔What does A-F represent?
✔✔What is a trickling filter? - ✔✔A fixed film process where wastewater trickles over
media, usually rock or plastic. Wastes are then consumed by layers of bacteria,
protozoa, fungi, and other organisms that live on the media.
✔✔What are the five basic parts in a trickling filter? - ✔✔- Filter floor
- Underdrain system
- Walls
- Filter media
- Distribution arms
✔✔What is the material that sloughs off the trickling filter that settles in the clarifier? -
✔✔Humus sludge
✔✔What is super important about the distribution arms on a trickling filter? - ✔✔Orifices
or nozzles on the rotating arms should be inspected daily for clogging and cleaned if
necessary. There should be no trash or large debris through the filter.
✔✔How do Rotating Biological Contactors spin? - ✔✔Each unit is driven either by a
motor with a gear reducer or by air trapped in air cups
✔✔In Rotating Biological Contactors, what is the biological growth like? - ✔✔The entire
wetted surface area of the disc becomes covered by a 0.05-0.1 inch film of gray to
brown biological growth. It contains approximately 50,000 mg/L of solids
✔✔What can advanced treatment processes do that secondary treatment can't? -
✔✔Advanced treatment processes strive to provide a higher removal level of specific
compounds, suspended solids, and oxygen-demanding materials that cannot be
achieved through secondary treatment alone.
✔✔In advanced treatment processes, what is the most important factor affecting filter
performance? - ✔✔the quality of the secondary effluent being applied to the filter - low
in solids
✔✔In advanced treatment, a filtration process should remove about ____ of the TSS
applied - ✔✔70%-90%
