Michigan Wastewater Treatment
Operator Level 1 Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. In wastewater treatment, the primary purpose of screening is to:
A. Remove dissolved organic matter
B. Adjust pH levels
C. Remove large solids and debris
D. Reduce nutrient levels
Screening is used to remove large solids and debris from influent
wastewater before further treatment processes.
2. The biological process that breaks down organic material in
wastewater using microorganisms is known as:
A. Filtration
B. Aerobic digestion
C. Sedimentation
D. Chemical precipitation
Aerobic digestion uses oxygen-dependent microorganisms to
biologically break down organic matter.
3. In a conventional activated sludge system, the purpose of the aeration
tank is to:
A. Clarify treated effluent
B. Remove grit
C. Provide oxygen to microorganisms for biodegradation
D. Sludge dewatering
, The aeration tank supplies oxygen to support microbial breakdown
of organic pollutants.
4. The measure of the amount of oxygen consumed by microorganisms
during the decomposition of organic matter over five days at 20°C is
abbreviated as:
A. COD
B. TSS
C. BOD₅
D. pH
BOD₅ (Biochemical Oxygen Demand over 5 days at 20°C) quantifies
biodegradable organic load.
5. A rapid drop in pH within a treatment process can negatively affect:
A. TSS removal
B. Biological activity
C. Sludge thickness
D. Dissolved oxygen readings
Microorganisms in biological treatment require stable pH; extreme
changes inhibit their activity.
6. The primary clarifier in a wastewater plant mainly functions to
remove:
A. Dissolved gases
B. Microorganisms
C. Nutrients
D. Settleable solids
Primary clarifiers allow heavier solids to settle out of wastewater by
gravity.
7. The ratio of volatile solids to total solids in sludge is an indicator of:
A. pH
B. Alkalinity
C. Temperature
D. Organic content
VS/TS ratio estimates how much of the solids in sludge are organic
and biodegradable.
8. The purpose of grit removal in preliminary treatment is to:
A. Reduce BOD load
, B. Remove toxic chemicals
C. Prevent abrasion of equipment
D. Improve disinfection
Grit can cause wear and tear on pumps and interference with
downstream processes.
9. Chlorination in wastewater treatment is primarily used for:
A. Nutrient removal
B. pH adjustment
C. Solids separation
D. Disinfection of pathogens
Chlorination disinfects treated effluent by killing or inactivating
pathogens.
10. The effluent discharge must meet regulatory limits for:
A. Heavy metals only
B. Influent characteristics
C. Multiple parameters including BOD and TSS
D. Air emissions
Environmental regulations require effluent compliance for
parameters like BOD, TSS, pH, nutrients.
11. Sludge age, or mean cell residence time, affects:
A. Influent flow
B. Grit removal
C. Biological system stability
D. Chlorine dosage
Sludge age influences microbial populations and treatment
performance in activated sludge.
12. In wastewater laboratory testing, turbidity measures:
A. Chemical toxicity
B. Cloudiness of water due to suspended solids
C. Dissolved oxygen
D. Sludge settleability
Turbidity indicates water clarity affected by suspended particles.
13. Total suspended solids (TSS) in effluent should be minimized to:
A. Reduce odor
B. Increase alkalinity
Operator Level 1 Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. In wastewater treatment, the primary purpose of screening is to:
A. Remove dissolved organic matter
B. Adjust pH levels
C. Remove large solids and debris
D. Reduce nutrient levels
Screening is used to remove large solids and debris from influent
wastewater before further treatment processes.
2. The biological process that breaks down organic material in
wastewater using microorganisms is known as:
A. Filtration
B. Aerobic digestion
C. Sedimentation
D. Chemical precipitation
Aerobic digestion uses oxygen-dependent microorganisms to
biologically break down organic matter.
3. In a conventional activated sludge system, the purpose of the aeration
tank is to:
A. Clarify treated effluent
B. Remove grit
C. Provide oxygen to microorganisms for biodegradation
D. Sludge dewatering
, The aeration tank supplies oxygen to support microbial breakdown
of organic pollutants.
4. The measure of the amount of oxygen consumed by microorganisms
during the decomposition of organic matter over five days at 20°C is
abbreviated as:
A. COD
B. TSS
C. BOD₅
D. pH
BOD₅ (Biochemical Oxygen Demand over 5 days at 20°C) quantifies
biodegradable organic load.
5. A rapid drop in pH within a treatment process can negatively affect:
A. TSS removal
B. Biological activity
C. Sludge thickness
D. Dissolved oxygen readings
Microorganisms in biological treatment require stable pH; extreme
changes inhibit their activity.
6. The primary clarifier in a wastewater plant mainly functions to
remove:
A. Dissolved gases
B. Microorganisms
C. Nutrients
D. Settleable solids
Primary clarifiers allow heavier solids to settle out of wastewater by
gravity.
7. The ratio of volatile solids to total solids in sludge is an indicator of:
A. pH
B. Alkalinity
C. Temperature
D. Organic content
VS/TS ratio estimates how much of the solids in sludge are organic
and biodegradable.
8. The purpose of grit removal in preliminary treatment is to:
A. Reduce BOD load
, B. Remove toxic chemicals
C. Prevent abrasion of equipment
D. Improve disinfection
Grit can cause wear and tear on pumps and interference with
downstream processes.
9. Chlorination in wastewater treatment is primarily used for:
A. Nutrient removal
B. pH adjustment
C. Solids separation
D. Disinfection of pathogens
Chlorination disinfects treated effluent by killing or inactivating
pathogens.
10. The effluent discharge must meet regulatory limits for:
A. Heavy metals only
B. Influent characteristics
C. Multiple parameters including BOD and TSS
D. Air emissions
Environmental regulations require effluent compliance for
parameters like BOD, TSS, pH, nutrients.
11. Sludge age, or mean cell residence time, affects:
A. Influent flow
B. Grit removal
C. Biological system stability
D. Chlorine dosage
Sludge age influences microbial populations and treatment
performance in activated sludge.
12. In wastewater laboratory testing, turbidity measures:
A. Chemical toxicity
B. Cloudiness of water due to suspended solids
C. Dissolved oxygen
D. Sludge settleability
Turbidity indicates water clarity affected by suspended particles.
13. Total suspended solids (TSS) in effluent should be minimized to:
A. Reduce odor
B. Increase alkalinity
