Wastewater Exam Class C Questions
and Answers | Latest Version |
2025/2026 | Correct & Verified
What does BOD stand for in wastewater treatment?
✔✔a) Biological Oxygen Demand
b) Basic Organic Density
c) Biochemical Oxidation Depth
d) Balanced Oxygen Distribution
Why is primary sedimentation performed in wastewater treatment?
✔✔a) To remove settleable solids before biological treatment
b) To disinfect wastewater
c) To remove dissolved nutrients
d) To remove gases
Which microorganism is commonly responsible for breaking down organic matter in secondary
treatment?
a) Viruses
1
,b) Algae
✔✔c) Bacteria
d) Protozoa
What is the main purpose of aeration in secondary treatment?
a) To remove heavy metals
✔✔b) To provide oxygen for microbial decomposition
c) To reduce pH
d) To coagulate solids
Why is sludge thickening performed before disposal?
a) To remove pathogens
b) To chlorinate the sludge
✔✔c) To reduce water content and volume
d) To neutralize pH
Which chemical is commonly used for disinfection in wastewater treatment?
a) Sulfuric acid
2
,✔✔b) Chlorine
c) Sodium hydroxide
d) Aluminum sulfate
What is the purpose of a grit chamber in wastewater treatment?
a) To remove dissolved nutrients
✔✔b) To remove sand, gravel, and other heavy particles
c) To reduce BOD
d) To disinfect water
Which process removes nitrogen from wastewater?
a) Coagulation
✔✔b) Nitrification and denitrification
c) Sedimentation
d) Flotation
Why is pH control important in wastewater treatment?
✔✔a) To optimize chemical and biological processes
3
, b) To remove sand and grit
c) To increase BOD
d) To remove oxygen
Which unit operation removes floating solids from wastewater?
a) Filtration
✔✔b) Skimming or oil separation
c) Aeration
d) Clarification
What is the purpose of an activated sludge process?
✔✔a) To biologically degrade organic matter using aerated microbial biomass
b) To chemically disinfect water
c) To remove metals
d) To adjust pH
Why are chlorine contact tanks important in wastewater treatment?
a) To remove BOD
4
and Answers | Latest Version |
2025/2026 | Correct & Verified
What does BOD stand for in wastewater treatment?
✔✔a) Biological Oxygen Demand
b) Basic Organic Density
c) Biochemical Oxidation Depth
d) Balanced Oxygen Distribution
Why is primary sedimentation performed in wastewater treatment?
✔✔a) To remove settleable solids before biological treatment
b) To disinfect wastewater
c) To remove dissolved nutrients
d) To remove gases
Which microorganism is commonly responsible for breaking down organic matter in secondary
treatment?
a) Viruses
1
,b) Algae
✔✔c) Bacteria
d) Protozoa
What is the main purpose of aeration in secondary treatment?
a) To remove heavy metals
✔✔b) To provide oxygen for microbial decomposition
c) To reduce pH
d) To coagulate solids
Why is sludge thickening performed before disposal?
a) To remove pathogens
b) To chlorinate the sludge
✔✔c) To reduce water content and volume
d) To neutralize pH
Which chemical is commonly used for disinfection in wastewater treatment?
a) Sulfuric acid
2
,✔✔b) Chlorine
c) Sodium hydroxide
d) Aluminum sulfate
What is the purpose of a grit chamber in wastewater treatment?
a) To remove dissolved nutrients
✔✔b) To remove sand, gravel, and other heavy particles
c) To reduce BOD
d) To disinfect water
Which process removes nitrogen from wastewater?
a) Coagulation
✔✔b) Nitrification and denitrification
c) Sedimentation
d) Flotation
Why is pH control important in wastewater treatment?
✔✔a) To optimize chemical and biological processes
3
, b) To remove sand and grit
c) To increase BOD
d) To remove oxygen
Which unit operation removes floating solids from wastewater?
a) Filtration
✔✔b) Skimming or oil separation
c) Aeration
d) Clarification
What is the purpose of an activated sludge process?
✔✔a) To biologically degrade organic matter using aerated microbial biomass
b) To chemically disinfect water
c) To remove metals
d) To adjust pH
Why are chlorine contact tanks important in wastewater treatment?
a) To remove BOD
4
