TCEQ WASTEWATER CLASS D LICENSE
ACTUAL PAPER 2026 QUESTIONS ANSWERS
GRADED A+
◉ What are the benefits of the collection system? Answer: - Removal
of health hazards
- Prevention of odors and flies
- Cleanliness and appearance
- Comfort and convenience
◉ Septic vs. Fresh wastewater? Answer: Septic wastewater doesn't
contain dissolved oxygen and is difficult to treat. Fresh wastewater
contains dissolved oxygen and is easier to treat, which results in
higher quality effluent
◉ Inflow Answer: Surface runoff that enters the collection system
◉ Infiltration Answer: Groundwater that enters the collection
system through holes, cracks, etc.
◉ What is the average domestic contribution to the collection
system? (Per person/day) Answer: 100 gallons per day
,◉ What are the four wastewater characteristics? Answer: Physical,
Chemical, Bacteriological, and Radiological
◉ Domestic wastewater is ___% water and ___% solids Answer:
99.9% water, 0.1% solids
◉ Settleable solids Answer: Suspended solids that will settle when
wastewater flow is still or slow moving
◉ What is the pH scale range? Answer: 0 (most acidic) to 14 (most
basic), 7 is neutral
◉ Does septic or freshwater have a lower pH? Why? Answer: Septic
has lower pH due to volatile acids formed from wastewater
decomposition
◉ What is Hydrogen Sulfide (H2S)? When does it occur? Answer: A
colorless, toxic, and flammable gas that resembles the smell of rotten
eggs. It results from the bacterial breakdown of organic matter in
the absence of oxygen. It is heavier than air.
◉ What is Methane? (CH4) What percentage of methane is in
digester gas? Answer: A colorless, odorless, and highly flammable
gas. Methane is an asphyxiant and is lighter than air. Digester gas
, contains 65% methane and is used for heating fuel or operating
equipment.
◉ What is carbon dioxide? (CO2) Answer: A colorless, odorless gas
that has a suffocating effect. When inhaled at higher than normal
concentrations, it can produce a sour taste in the mouth and a
stinging sensation in the nose and throat.
◉ What is carbon monoxide? (CO) Answer: A colorless, odorless,
and tasteless gas
◉ Why is oil and grease a concern if present in wastewater? Answer:
It may cause explosions, fires, line blockages, and odor
◉ What are chlorides and why are excessive chlorides in wastewater
bad? Answer: Excessive chlorides interfere with treatment
processes, especially trickling filters. They also affect laboratory
tests.
◉ What does the BOD test measure? Answer: It measures
wastewater strength and the oxygen depleting effect of wastewater
effluent on the receiving stream. Specifically, it indicates the amount
of organic matter that can be oxidized by biological and chemical
action in five days at 20 degrees Celsius.
ACTUAL PAPER 2026 QUESTIONS ANSWERS
GRADED A+
◉ What are the benefits of the collection system? Answer: - Removal
of health hazards
- Prevention of odors and flies
- Cleanliness and appearance
- Comfort and convenience
◉ Septic vs. Fresh wastewater? Answer: Septic wastewater doesn't
contain dissolved oxygen and is difficult to treat. Fresh wastewater
contains dissolved oxygen and is easier to treat, which results in
higher quality effluent
◉ Inflow Answer: Surface runoff that enters the collection system
◉ Infiltration Answer: Groundwater that enters the collection
system through holes, cracks, etc.
◉ What is the average domestic contribution to the collection
system? (Per person/day) Answer: 100 gallons per day
,◉ What are the four wastewater characteristics? Answer: Physical,
Chemical, Bacteriological, and Radiological
◉ Domestic wastewater is ___% water and ___% solids Answer:
99.9% water, 0.1% solids
◉ Settleable solids Answer: Suspended solids that will settle when
wastewater flow is still or slow moving
◉ What is the pH scale range? Answer: 0 (most acidic) to 14 (most
basic), 7 is neutral
◉ Does septic or freshwater have a lower pH? Why? Answer: Septic
has lower pH due to volatile acids formed from wastewater
decomposition
◉ What is Hydrogen Sulfide (H2S)? When does it occur? Answer: A
colorless, toxic, and flammable gas that resembles the smell of rotten
eggs. It results from the bacterial breakdown of organic matter in
the absence of oxygen. It is heavier than air.
◉ What is Methane? (CH4) What percentage of methane is in
digester gas? Answer: A colorless, odorless, and highly flammable
gas. Methane is an asphyxiant and is lighter than air. Digester gas
, contains 65% methane and is used for heating fuel or operating
equipment.
◉ What is carbon dioxide? (CO2) Answer: A colorless, odorless gas
that has a suffocating effect. When inhaled at higher than normal
concentrations, it can produce a sour taste in the mouth and a
stinging sensation in the nose and throat.
◉ What is carbon monoxide? (CO) Answer: A colorless, odorless,
and tasteless gas
◉ Why is oil and grease a concern if present in wastewater? Answer:
It may cause explosions, fires, line blockages, and odor
◉ What are chlorides and why are excessive chlorides in wastewater
bad? Answer: Excessive chlorides interfere with treatment
processes, especially trickling filters. They also affect laboratory
tests.
◉ What does the BOD test measure? Answer: It measures
wastewater strength and the oxygen depleting effect of wastewater
effluent on the receiving stream. Specifically, it indicates the amount
of organic matter that can be oxidized by biological and chemical
action in five days at 20 degrees Celsius.
