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TCEQ WASTEWATER LICENSE EXAM
100 QUESTIONS AND CORRECT
DETAILED ANSWERS LATEST 2025-
2026 UPDATE |AREADY A GRADED
|NEW AND REVISED
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
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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
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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.
What are pathogens? What are two viral diseases that could be carried in
wastewater? - ANSWER- Polio and infectious hepatitis
What are precautions individuals can take to protect against pathogens in
the collection system? How do communities overall prevent waterborne
disease? - ANSWER- - Wear cut-resistant gloves
- Wash after contacting wastewater
- Do not eat or smoke around wastewater
- Disinfect equipment with bleach
- Well-maintained water system
- Sanitary collection system
- Well-operated wastewater treatment plant
What are the steps of the Water Use Cycle? - ANSWER- Environment --
> Water Treatment --> Water Distribution System --> Customer Use -->
Wastewater Collection System --> Wastewater Treatment -->
Environment
What are the benefits of the collection system? - ANSWER- - Removal
of health hazards
- Prevention of odors and flies
- Cleanliness and appearance
TCEQ WASTEWATER LICENSE EXAM
100 QUESTIONS AND CORRECT
DETAILED ANSWERS LATEST 2025-
2026 UPDATE |AREADY A GRADED
|NEW AND REVISED
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
,2|Page
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
, 3|Page
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.
What are pathogens? What are two viral diseases that could be carried in
wastewater? - ANSWER- Polio and infectious hepatitis
What are precautions individuals can take to protect against pathogens in
the collection system? How do communities overall prevent waterborne
disease? - ANSWER- - Wear cut-resistant gloves
- Wash after contacting wastewater
- Do not eat or smoke around wastewater
- Disinfect equipment with bleach
- Well-maintained water system
- Sanitary collection system
- Well-operated wastewater treatment plant
What are the steps of the Water Use Cycle? - ANSWER- Environment --
> Water Treatment --> Water Distribution System --> Customer Use -->
Wastewater Collection System --> Wastewater Treatment -->
Environment
What are the benefits of the collection system? - ANSWER- - Removal
of health hazards
- Prevention of odors and flies
- Cleanliness and appearance
