Level I sample questions
4 free sample questions on biological treatment for the Washington Level I wastewater treatment operator exam. Try each one, then open the answer to read the explanation.
What does an aeration diffuser do?
Answer: C. Release air as bubbles into wastewater
A diffuser releases compressed air as bubbles into wastewater, allowing oxygen to transfer into the water.
How does a rotating biological contactor operate?
Answer: A. Discs rotate through wastewater and air
An RBC slowly rotates biological discs through wastewater and air so attached microorganisms contact both the wastewater and oxygen.
What does return activated sludge carry back to the aeration basin?
Answer: B. Settled biological solids
Return activated sludge moves settled biological solids from the secondary clarifier back to the aeration basin.
Why is some activated sludge removed from the treatment process?
Answer: D. Control the amount and age of biological solids
Microorganisms grow as they treat wastewater. Removing excess activated sludge keeps the biological-solids inventory and sludge age under control.
Keep practicing
Operator Master has 4 Level I biological treatment questions, free, with an explanation after every answer.
More topics