Texas Wastewater A Exam Questions With
Accurate Answers 2025\2026 A+ Grade
Describe proper design of force main wastewater lines.
- accurate answers-Minimum two fps velocity with the smallest pump
operating alone. Minimum four inch diameter pipe with 150 psi rating.
Describe proper design of gravity wastewater lines.
- accurate answers-Designed to flow half full ,under normal conditions, at a
minimum of two fps and a maximum of ten fps.
What is the effective chlorine disinfecting agent?
- accurate answers-Hypochlorous Acid (HOCl)
A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet deep.
The weir is 2 feet inside the outer clarifier wall. The flow is 1.0 MGD. The weir
and outflow channel is 3 feet deep. a. What is the detention time in hours?
- accurate answers-5.08. hrs
What activated process cannot nitrify in a single stage?
- accurate answers-Contact Stabilization
What is the GPM output of a piston pump with an 8-inch diameter piston with
a 10-inch stroke operating at 50 strokes per minute?
- accurate answers-108.8 gpm
A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet deep.
The weir is 2 feet inside the outer clarifier wall. The flow is 1.0 MGD. The weir
and outflow channel is 3 feet deep.
What is the surface loading in gal/ft2/day?
What is the weir loading in gal linear ft/day?
- accurate answers-353.68 gallons & 5684.11
A primary clarifier has a flow of 3.0 MGD and has a diameter of 100 feet. It is
12 feet deep and has 24 inches of freeboard. What is the detention time in
hours?
- accurate answers-4.7 hrs
, Anaerobic digester gas should contain?
- accurate answers-65-75% methane, 25-35% carbon dioxide and 1-5%
nitrogen.
An activated sludge plant has an average daily flow of 3.5 MG. The aeration
tank capacity is 1.2 MG with a MLSS concentration of 3200 mg/L. The clarifier
has a capacity of 400,000 gallons with a MLSS concentration of 6,000 mg/L.
The wasting rate is 40,000 gallons per day with a MLSS concentration of 8,
000 mg/L. The effluent TSS is 18 mg/L. Assuming volatile concentrations of
70%, what is the MCRT and what type of activated sludge plant should this
be?
- accurate answers-16.29 Days
What are some of the causes of filaments in the aeration basin?
- accurate answers-a. low DO
b. low organic loading
c. septic wastes
d. nutrient deficiencies .
e. high sulfur content
When an RBC is operating correctly, how will the slime appear on the media?
- accurate answers-Grey to brown 0.05 to 0.1 inches thick
What activated sludge process does not achieve complete nitrification?
- accurate answers-Contact Stabilization
In the selection of forced main wastewater piping, what is the minimum
working pressure?
- accurate answers-150 psi
The oxygen depletion of BOD dilution water should not exceed
- accurate answers-0.2 mg/L.
What is the minimum air gap when making water and wastewater
connections?
- accurate answers-Minimum of one inch or twice the inlet pipe size
whichever is greater.
Accurate Answers 2025\2026 A+ Grade
Describe proper design of force main wastewater lines.
- accurate answers-Minimum two fps velocity with the smallest pump
operating alone. Minimum four inch diameter pipe with 150 psi rating.
Describe proper design of gravity wastewater lines.
- accurate answers-Designed to flow half full ,under normal conditions, at a
minimum of two fps and a maximum of ten fps.
What is the effective chlorine disinfecting agent?
- accurate answers-Hypochlorous Acid (HOCl)
A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet deep.
The weir is 2 feet inside the outer clarifier wall. The flow is 1.0 MGD. The weir
and outflow channel is 3 feet deep. a. What is the detention time in hours?
- accurate answers-5.08. hrs
What activated process cannot nitrify in a single stage?
- accurate answers-Contact Stabilization
What is the GPM output of a piston pump with an 8-inch diameter piston with
a 10-inch stroke operating at 50 strokes per minute?
- accurate answers-108.8 gpm
A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet deep.
The weir is 2 feet inside the outer clarifier wall. The flow is 1.0 MGD. The weir
and outflow channel is 3 feet deep.
What is the surface loading in gal/ft2/day?
What is the weir loading in gal linear ft/day?
- accurate answers-353.68 gallons & 5684.11
A primary clarifier has a flow of 3.0 MGD and has a diameter of 100 feet. It is
12 feet deep and has 24 inches of freeboard. What is the detention time in
hours?
- accurate answers-4.7 hrs
, Anaerobic digester gas should contain?
- accurate answers-65-75% methane, 25-35% carbon dioxide and 1-5%
nitrogen.
An activated sludge plant has an average daily flow of 3.5 MG. The aeration
tank capacity is 1.2 MG with a MLSS concentration of 3200 mg/L. The clarifier
has a capacity of 400,000 gallons with a MLSS concentration of 6,000 mg/L.
The wasting rate is 40,000 gallons per day with a MLSS concentration of 8,
000 mg/L. The effluent TSS is 18 mg/L. Assuming volatile concentrations of
70%, what is the MCRT and what type of activated sludge plant should this
be?
- accurate answers-16.29 Days
What are some of the causes of filaments in the aeration basin?
- accurate answers-a. low DO
b. low organic loading
c. septic wastes
d. nutrient deficiencies .
e. high sulfur content
When an RBC is operating correctly, how will the slime appear on the media?
- accurate answers-Grey to brown 0.05 to 0.1 inches thick
What activated sludge process does not achieve complete nitrification?
- accurate answers-Contact Stabilization
In the selection of forced main wastewater piping, what is the minimum
working pressure?
- accurate answers-150 psi
The oxygen depletion of BOD dilution water should not exceed
- accurate answers-0.2 mg/L.
What is the minimum air gap when making water and wastewater
connections?
- accurate answers-Minimum of one inch or twice the inlet pipe size
whichever is greater.
