CWEA Wastewater Operator Certification Exam QUESTIONS AND CORRECT ANSWERS
WITH RATIONALES
Exam coverage
• preliminary treatment
• primary treatment
• biological treatment
• secondary clarification
• disinfection
• solids handling
• process control
• sampling and laboratory work
• operator safety
• plant documentation
,1. When documenting or evaluating this situation, which statement is most accurate
about Preliminary treatment removes or reduces large debris, grit, and other materials
that could interfere with downstream processes.. Which answer best applies the
underlying wastewater operator principle in this situation?
A. Secondary clarification separates biological solids from treated liquid..
B. Primary treatment removes settleable solids and floating materials by physical processes..
C. Preliminary treatment removes or reduces large debris, grit, and other materials that could
interfere with downstream processes..
D. Biological treatment uses microorganisms to convert dissolved or particulate organic matter
into biomass and other products..
Correct answer: C
Rationale: The correct choice directly states the governing principle: Preliminary treatment
removes or reduces large debris, grit, and other materials that could interfere with downstream
processes.. The alternatives describe related concepts but do not directly answer the issue
presented.
2. Which statement most accurately explains the principle involved when Primary
treatment removes settleable solids and floating materials by physical processes..
Which answer best applies the underlying wastewater operator principle in this
situation?
A. Primary treatment removes settleable solids and floating materials by physical processes..
,B. Biological treatment uses microorganisms to convert dissolved or particulate organic matter
into biomass and other products..
C. Secondary clarification separates biological solids from treated liquid..
D. Disinfection reduces pathogenic organisms before permitted discharge or reuse..
Correct answer: A
Rationale: The correct choice directly states the governing principle: Primary treatment
removes settleable solids and floating materials by physical processes.. The alternatives
describe related concepts but do not directly answer the issue presented.
3. During a routine review, which option best describes why Biological treatment uses
microorganisms to convert dissolved or particulate organic matter into biomass and
other products.. Which answer best applies the underlying wastewater operator
principle in this situation?
A. Secondary clarification separates biological solids from treated liquid..
B. Solids handling includes thickening, stabilization, dewatering, and appropriate disposal or
reuse..
C. Biological treatment uses microorganisms to convert dissolved or particulate organic matter
into biomass and other products..
D. Disinfection reduces pathogenic organisms before permitted discharge or reuse..
Correct answer: C
, Rationale: The correct choice directly states the governing principle: Biological treatment uses
microorganisms to convert dissolved or particulate organic matter into biomass and other
products.. The alternatives describe related concepts but do not directly answer the issue
presented.
4. A supervisor asks which practice is most appropriate when Secondary clarification
separates biological solids from treated liquid.. Which answer best applies the
underlying wastewater operator principle in this situation?
A. Solids handling includes thickening, stabilization, dewatering, and appropriate disposal or
reuse..
B. Process control uses measurements and operating adjustments to maintain treatment
performance..
C. Disinfection reduces pathogenic organisms before permitted discharge or reuse..
D. Secondary clarification separates biological solids from treated liquid..
Correct answer: D
Rationale: The correct choice directly states the governing principle: Secondary clarification
separates biological solids from treated liquid.. The alternatives describe related concepts but
do not directly answer the issue presented.
5. Which choice correctly identifies the main reason that Disinfection reduces
pathogenic organisms before permitted discharge or reuse.. Which answer best applies
the underlying wastewater operator principle in this situation?
WITH RATIONALES
Exam coverage
• preliminary treatment
• primary treatment
• biological treatment
• secondary clarification
• disinfection
• solids handling
• process control
• sampling and laboratory work
• operator safety
• plant documentation
,1. When documenting or evaluating this situation, which statement is most accurate
about Preliminary treatment removes or reduces large debris, grit, and other materials
that could interfere with downstream processes.. Which answer best applies the
underlying wastewater operator principle in this situation?
A. Secondary clarification separates biological solids from treated liquid..
B. Primary treatment removes settleable solids and floating materials by physical processes..
C. Preliminary treatment removes or reduces large debris, grit, and other materials that could
interfere with downstream processes..
D. Biological treatment uses microorganisms to convert dissolved or particulate organic matter
into biomass and other products..
Correct answer: C
Rationale: The correct choice directly states the governing principle: Preliminary treatment
removes or reduces large debris, grit, and other materials that could interfere with downstream
processes.. The alternatives describe related concepts but do not directly answer the issue
presented.
2. Which statement most accurately explains the principle involved when Primary
treatment removes settleable solids and floating materials by physical processes..
Which answer best applies the underlying wastewater operator principle in this
situation?
A. Primary treatment removes settleable solids and floating materials by physical processes..
,B. Biological treatment uses microorganisms to convert dissolved or particulate organic matter
into biomass and other products..
C. Secondary clarification separates biological solids from treated liquid..
D. Disinfection reduces pathogenic organisms before permitted discharge or reuse..
Correct answer: A
Rationale: The correct choice directly states the governing principle: Primary treatment
removes settleable solids and floating materials by physical processes.. The alternatives
describe related concepts but do not directly answer the issue presented.
3. During a routine review, which option best describes why Biological treatment uses
microorganisms to convert dissolved or particulate organic matter into biomass and
other products.. Which answer best applies the underlying wastewater operator
principle in this situation?
A. Secondary clarification separates biological solids from treated liquid..
B. Solids handling includes thickening, stabilization, dewatering, and appropriate disposal or
reuse..
C. Biological treatment uses microorganisms to convert dissolved or particulate organic matter
into biomass and other products..
D. Disinfection reduces pathogenic organisms before permitted discharge or reuse..
Correct answer: C
, Rationale: The correct choice directly states the governing principle: Biological treatment uses
microorganisms to convert dissolved or particulate organic matter into biomass and other
products.. The alternatives describe related concepts but do not directly answer the issue
presented.
4. A supervisor asks which practice is most appropriate when Secondary clarification
separates biological solids from treated liquid.. Which answer best applies the
underlying wastewater operator principle in this situation?
A. Solids handling includes thickening, stabilization, dewatering, and appropriate disposal or
reuse..
B. Process control uses measurements and operating adjustments to maintain treatment
performance..
C. Disinfection reduces pathogenic organisms before permitted discharge or reuse..
D. Secondary clarification separates biological solids from treated liquid..
Correct answer: D
Rationale: The correct choice directly states the governing principle: Secondary clarification
separates biological solids from treated liquid.. The alternatives describe related concepts but
do not directly answer the issue presented.
5. Which choice correctly identifies the main reason that Disinfection reduces
pathogenic organisms before permitted discharge or reuse.. Which answer best applies
the underlying wastewater operator principle in this situation?
