WASTEWATER TREATMENT OPERATIONS EXAM
SCRIPT 2026 COMPLETE QUESTIONS AND
CORRECT ANSWERS
◉What best describes pre-chlorination? Answer: Addition of chlorine to
wastewater at the entrance to the plant, and used for odor control, BOD
reduction, grease removal, and aid sedimentation
◉When would you expect reduced algae population and less oxygen
released into a pond? Answer: Fall and winter, when the weather is cool
and sunlight is reduced
◉What is the first step of lockout/tagout procedure? Answer: Notify all
affected employees that a lockout/tagout system is going to be used and
the reason why
◉What type of process is the activated sludge system? Answer: Aerobic
◉What will happen if too much raw sludge is added to the digester?
Answer: Acid fermenters will predominate and lower the pH
, ◉What might cause sludge to rise in a clarifier? Answer: Gasification
from aging sludge
◉What happens when carbon dioxide is removed from a pond? Answer:
Increases pH
◉How much dissolved oxygen should be in a conventional activated
sludge system if good effluent is being produced? Answer: 2 to 4 mg/L
◉What is the typical concentration of mixed liquor suspended solids in a
conventional activated sludge process? Answer: 1,000 to 4,500 mg/L
◉The temperature of the plant influent is? Answer: Slighty warmer than
tap water
◉The purpose of disinfection is to? Answer: Destruction or inactivation
of pathogenic bacteria
◉What must you do before entering a room with harmful concentration
of chlorine gas in the air? Answer: Wear self contained breathing
apparatus(scba)
◉What does black sludge at the bottom of a secondary clarifier located
downstream of a trickling filter signify? Answer: Sludge has stayed in
the secondary clarifier too long
SCRIPT 2026 COMPLETE QUESTIONS AND
CORRECT ANSWERS
◉What best describes pre-chlorination? Answer: Addition of chlorine to
wastewater at the entrance to the plant, and used for odor control, BOD
reduction, grease removal, and aid sedimentation
◉When would you expect reduced algae population and less oxygen
released into a pond? Answer: Fall and winter, when the weather is cool
and sunlight is reduced
◉What is the first step of lockout/tagout procedure? Answer: Notify all
affected employees that a lockout/tagout system is going to be used and
the reason why
◉What type of process is the activated sludge system? Answer: Aerobic
◉What will happen if too much raw sludge is added to the digester?
Answer: Acid fermenters will predominate and lower the pH
, ◉What might cause sludge to rise in a clarifier? Answer: Gasification
from aging sludge
◉What happens when carbon dioxide is removed from a pond? Answer:
Increases pH
◉How much dissolved oxygen should be in a conventional activated
sludge system if good effluent is being produced? Answer: 2 to 4 mg/L
◉What is the typical concentration of mixed liquor suspended solids in a
conventional activated sludge process? Answer: 1,000 to 4,500 mg/L
◉The temperature of the plant influent is? Answer: Slighty warmer than
tap water
◉The purpose of disinfection is to? Answer: Destruction or inactivation
of pathogenic bacteria
◉What must you do before entering a room with harmful concentration
of chlorine gas in the air? Answer: Wear self contained breathing
apparatus(scba)
◉What does black sludge at the bottom of a secondary clarifier located
downstream of a trickling filter signify? Answer: Sludge has stayed in
the secondary clarifier too long
