Wastewater Certification Exam | Questions
and Answers | 100% Verified Solutions |
2022 Edition
Section 1: Wastewater Treatment Fundamentals (10
Questions)
1. Primary Treatment Purpose
What is the main purpose of primary treatment in wastewater? A) Biological removal of
organics B) Settling of solids by gravity C) Disinfection of wastewater D) Removal of nutrients
Correct Answer: B) Settling of solids by gravity Rationale:
● Primary treatment uses sedimentation and screening to remove settleable solids
and floating materials.
● A) Incorrect: Biological removal occurs in secondary treatment.
● C) Incorrect: Disinfection is a tertiary process.
● D) Incorrect: Nutrient removal requires advanced treatment.
2. Secondary Treatment Goal
The primary goal of secondary treatment is to: A) Remove grit and large debris B) Remove
dissolved and suspended organic matter via biological processes C) Disinfect effluent D)
Thicken sludge
Correct Answer: B) Remove dissolved and suspended organic matter via biological
processes Rationale:
● Secondary treatment uses microorganisms to break down organic pollutants (e.g.,
activated sludge, trickling filters).
● A, C, D) Incorrect: These are primary, tertiary, or sludge-handling goals.
,3. Tertiary Treatment Function
Tertiary treatment is primarily used to: A) Remove grit B) Settle solids C) Further polish
effluent for reuse or strict discharge limits D) Thicken sludge
Correct Answer: C) Further polish effluent for reuse or strict discharge limits Rationale:
● Tertiary processes (e.g., filtration, disinfection) remove remaining contaminants (e.g.,
nutrients, pathogens).
● A, B, D) Incorrect: These occur in primary/secondary treatment or sludge handling.
4. Wastewater pH Impact
If influent wastewater has a pH of 5.0, the operator should: A) Add chlorine B) Adjust pH to
6.5–8.5 for optimal microbial activity C) Increase aeration D) Reduce sludge wasting
Correct Answer: B) Adjust pH to 6.5–8.5 for optimal microbial activity Rationale:
● Acidic pH (below 6.5) inhibits microbial growth in biological treatment.
● A, C, D) Incorrect: These do not address pH issues.
5. BOD Definition
Biochemical Oxygen Demand (BOD) measures: A) The amount of dissolved oxygen in water
B) The oxygen required by microorganisms to break down organic matter C) The total
suspended solids in wastewater D) The pH level of wastewater
Correct Answer: B) The oxygen required by microorganisms to break down organic
matter Rationale:
● BOD indicates organic pollution level; high BOD = more oxygen consumed by
microbes.
● A, C, D) Incorrect: These measure DO, TSS, or pH, not organic load.
6. TSS Definition
Total Suspended Solids (TSS) measures: A) Dissolved organic matter B) Solids retained on
a filter during testing C) Microbial population D) Chemical oxygen demand
, Correct Answer: B) Solids retained on a filter during testing Rationale:
● TSS quantifies non-dissolved solids in wastewater.
● A, C, D) Incorrect: These measure dissolved organics, microbes, or COD.
7. Wastewater Nitrogen Forms
The most common forms of nitrogen in wastewater are: A) Nitrate and sulfur B) Ammonia,
organic nitrogen, nitrite, and nitrate C) Phosphorus and potassium D) Chlorine and fluoride
Correct Answer: B) Ammonia, organic nitrogen, nitrite, and nitrate Rationale:
● Ammonia (NH₃) and organic nitrogen enter as waste; nitrification converts them to
nitrite (NO₂⁻) and nitrate (NO₃⁻).
● A, C, D) Incorrect: These are not nitrogen forms.
8. Phosphorus Removal Methods
Phosphorus is primarily removed in wastewater through: A) Chlorination B) Chemical
precipitation (e.g., alum, iron salts) or biological uptake C) UV disinfection D) Grit removal
Correct Answer: B) Chemical precipitation (e.g., alum, iron salts) or biological uptake
Rationale:
● Chemical addition binds phosphorus into insoluble compounds; biological
processes also remove it.
● A, C, D) Incorrect: These do not target phosphorus.
9. Wastewater Odor Cause
Hydrogen sulfide (H₂S) odors in wastewater are most commonly caused by: A) High
dissolved oxygen B) Anaerobic conditions (low or no oxygen) C) Alkaline pH D) Chlorine
residual
Correct Answer: B) Anaerobic conditions (low or no oxygen) Rationale:
● Anaerobic bacteria produce H₂S in septic conditions (e.g., stagnant sewers, sludge).
● A, C, D) Incorrect: These prevent or neutralize H₂S.
and Answers | 100% Verified Solutions |
2022 Edition
Section 1: Wastewater Treatment Fundamentals (10
Questions)
1. Primary Treatment Purpose
What is the main purpose of primary treatment in wastewater? A) Biological removal of
organics B) Settling of solids by gravity C) Disinfection of wastewater D) Removal of nutrients
Correct Answer: B) Settling of solids by gravity Rationale:
● Primary treatment uses sedimentation and screening to remove settleable solids
and floating materials.
● A) Incorrect: Biological removal occurs in secondary treatment.
● C) Incorrect: Disinfection is a tertiary process.
● D) Incorrect: Nutrient removal requires advanced treatment.
2. Secondary Treatment Goal
The primary goal of secondary treatment is to: A) Remove grit and large debris B) Remove
dissolved and suspended organic matter via biological processes C) Disinfect effluent D)
Thicken sludge
Correct Answer: B) Remove dissolved and suspended organic matter via biological
processes Rationale:
● Secondary treatment uses microorganisms to break down organic pollutants (e.g.,
activated sludge, trickling filters).
● A, C, D) Incorrect: These are primary, tertiary, or sludge-handling goals.
,3. Tertiary Treatment Function
Tertiary treatment is primarily used to: A) Remove grit B) Settle solids C) Further polish
effluent for reuse or strict discharge limits D) Thicken sludge
Correct Answer: C) Further polish effluent for reuse or strict discharge limits Rationale:
● Tertiary processes (e.g., filtration, disinfection) remove remaining contaminants (e.g.,
nutrients, pathogens).
● A, B, D) Incorrect: These occur in primary/secondary treatment or sludge handling.
4. Wastewater pH Impact
If influent wastewater has a pH of 5.0, the operator should: A) Add chlorine B) Adjust pH to
6.5–8.5 for optimal microbial activity C) Increase aeration D) Reduce sludge wasting
Correct Answer: B) Adjust pH to 6.5–8.5 for optimal microbial activity Rationale:
● Acidic pH (below 6.5) inhibits microbial growth in biological treatment.
● A, C, D) Incorrect: These do not address pH issues.
5. BOD Definition
Biochemical Oxygen Demand (BOD) measures: A) The amount of dissolved oxygen in water
B) The oxygen required by microorganisms to break down organic matter C) The total
suspended solids in wastewater D) The pH level of wastewater
Correct Answer: B) The oxygen required by microorganisms to break down organic
matter Rationale:
● BOD indicates organic pollution level; high BOD = more oxygen consumed by
microbes.
● A, C, D) Incorrect: These measure DO, TSS, or pH, not organic load.
6. TSS Definition
Total Suspended Solids (TSS) measures: A) Dissolved organic matter B) Solids retained on
a filter during testing C) Microbial population D) Chemical oxygen demand
, Correct Answer: B) Solids retained on a filter during testing Rationale:
● TSS quantifies non-dissolved solids in wastewater.
● A, C, D) Incorrect: These measure dissolved organics, microbes, or COD.
7. Wastewater Nitrogen Forms
The most common forms of nitrogen in wastewater are: A) Nitrate and sulfur B) Ammonia,
organic nitrogen, nitrite, and nitrate C) Phosphorus and potassium D) Chlorine and fluoride
Correct Answer: B) Ammonia, organic nitrogen, nitrite, and nitrate Rationale:
● Ammonia (NH₃) and organic nitrogen enter as waste; nitrification converts them to
nitrite (NO₂⁻) and nitrate (NO₃⁻).
● A, C, D) Incorrect: These are not nitrogen forms.
8. Phosphorus Removal Methods
Phosphorus is primarily removed in wastewater through: A) Chlorination B) Chemical
precipitation (e.g., alum, iron salts) or biological uptake C) UV disinfection D) Grit removal
Correct Answer: B) Chemical precipitation (e.g., alum, iron salts) or biological uptake
Rationale:
● Chemical addition binds phosphorus into insoluble compounds; biological
processes also remove it.
● A, C, D) Incorrect: These do not target phosphorus.
9. Wastewater Odor Cause
Hydrogen sulfide (H₂S) odors in wastewater are most commonly caused by: A) High
dissolved oxygen B) Anaerobic conditions (low or no oxygen) C) Alkaline pH D) Chlorine
residual
Correct Answer: B) Anaerobic conditions (low or no oxygen) Rationale:
● Anaerobic bacteria produce H₂S in septic conditions (e.g., stagnant sewers, sludge).
● A, C, D) Incorrect: These prevent or neutralize H₂S.
