Wastewater Grade 2 Study Questions
and Answers | Latest Version |
2025/2026 | Correct & Verified
What does BOD stand for in wastewater treatment?
a) Biological Organic Demand
b) Biochemical Oxygen Division
✔✔c) Biochemical Oxygen Demand
d) Biological Oxidation Density
What does a high BOD in wastewater indicate?
a) Low organic matter
✔✔b) High organic pollution
c) High oxygen levels
d) Low microbial activity
Which organisms are primarily responsible for breaking down organic matter in secondary
treatment?
a) Viruses
1
,b) Protozoa
✔✔c) Bacteria
d) Algae
What is the main function of an aeration tank?
a) Remove grit
b) Store wastewater
✔✔c) Provide oxygen to microorganisms
d) Separate sludge
Why is chlorine added to treated wastewater?
a) To increase alkalinity
✔✔b) To disinfect and kill pathogens
c) To add oxygen
d) To remove nitrogen
What is the purpose of a grit chamber?
a) Remove oils
2
,✔✔b) Remove sand and heavy particles
c) Remove dissolved gases
d) Remove sludge
Which type of sludge is produced during primary treatment?
a) Activated sludge
✔✔b) Raw sludge
c) Digested sludge
d) Anaerobic sludge
What does TSS stand for?
a) Total Salt Solids
✔✔b) Total Suspended Solids
c) Total Soluble Substances
d) Total Settled Solids
Why is dissolved oxygen important in activated sludge systems?
a) To prevent foaming
3
, ✔✔b) To support microbial activity
c) To reduce sludge volume
d) To remove grit
What is the purpose of a clarifier?
a) Add oxygen
✔✔b) Allow solids to settle
c) Disinfect water
d) Remove odors
Which gas is commonly produced in anaerobic digestion?
a) Oxygen
b) Nitrogen
✔✔c) Methane
d) Ozone
What is the main use of methane from digesters?
a) Fertilizer
4
and Answers | Latest Version |
2025/2026 | Correct & Verified
What does BOD stand for in wastewater treatment?
a) Biological Organic Demand
b) Biochemical Oxygen Division
✔✔c) Biochemical Oxygen Demand
d) Biological Oxidation Density
What does a high BOD in wastewater indicate?
a) Low organic matter
✔✔b) High organic pollution
c) High oxygen levels
d) Low microbial activity
Which organisms are primarily responsible for breaking down organic matter in secondary
treatment?
a) Viruses
1
,b) Protozoa
✔✔c) Bacteria
d) Algae
What is the main function of an aeration tank?
a) Remove grit
b) Store wastewater
✔✔c) Provide oxygen to microorganisms
d) Separate sludge
Why is chlorine added to treated wastewater?
a) To increase alkalinity
✔✔b) To disinfect and kill pathogens
c) To add oxygen
d) To remove nitrogen
What is the purpose of a grit chamber?
a) Remove oils
2
,✔✔b) Remove sand and heavy particles
c) Remove dissolved gases
d) Remove sludge
Which type of sludge is produced during primary treatment?
a) Activated sludge
✔✔b) Raw sludge
c) Digested sludge
d) Anaerobic sludge
What does TSS stand for?
a) Total Salt Solids
✔✔b) Total Suspended Solids
c) Total Soluble Substances
d) Total Settled Solids
Why is dissolved oxygen important in activated sludge systems?
a) To prevent foaming
3
, ✔✔b) To support microbial activity
c) To reduce sludge volume
d) To remove grit
What is the purpose of a clarifier?
a) Add oxygen
✔✔b) Allow solids to settle
c) Disinfect water
d) Remove odors
Which gas is commonly produced in anaerobic digestion?
a) Oxygen
b) Nitrogen
✔✔c) Methane
d) Ozone
What is the main use of methane from digesters?
a) Fertilizer
4
