Wastewater Operator Certification
Study Guide Grade 1 Questions and
Answers | Latest Version | 2025/2026 |
Correct & Verified
What type of bacteria requires oxygen to survive and treat wastewater?
✔✔Aerobic bacteria
What is the main purpose of a primary clarifier?
✔✔To settle out suspended solids and reduce organic load
What is the main purpose of secondary treatment?
✔✔To biologically remove dissolved and colloidal organic matter
What is the typical pH of raw wastewater?
✔✔Between 6.5 and 8.5
What is the most common disinfectant used in wastewater treatment?
✔✔Chlorine
1
,What is the purpose of a digester in wastewater treatment?
✔✔To stabilize sludge and reduce pathogens
What is the main product of anaerobic digestion?
✔✔Methane gas
What is the primary goal of sludge thickening?
✔✔To reduce the volume of sludge by removing water
What is TSS in wastewater analysis?
✔✔Total Suspended Solids
What is the purpose of return activated sludge (RAS)?
✔✔To maintain an adequate population of microorganisms in the aeration tank
What is the main cause of septic conditions in wastewater?
✔✔A lack of dissolved oxygen
2
,What is the main purpose of chlorination in wastewater?
✔✔To kill or inactivate pathogens before discharge
What does FOG stand for in wastewater operations?
✔✔Fats, Oils, and Grease
What is the purpose of a flow equalization basin?
✔✔To balance fluctuations in influent flow and load
What is a common symptom of filamentous bacteria in activated sludge?
✔✔Bulking sludge with poor settling
What type of bacteria is responsible for nitrification?
✔✔Nitrifying bacteria such as Nitrosomonas and Nitrobacter
What is the main purpose of a bar screen?
✔✔To remove rags, sticks, and other large solids
3
, What is the main danger of high chlorine residual in effluent?
✔✔It is toxic to fish and aquatic life
What is the function of a grit chamber?
✔✔To remove heavy inorganic materials like sand and gravel
What happens when sludge is not removed regularly from a clarifier?
✔✔It can carry over into the effluent and reduce treatment efficiency
What is the main purpose of secondary clarifiers?
✔✔To settle out biological solids after aeration
What is sludge dewatering designed to accomplish?
✔✔To reduce the water content of sludge for easier handling and disposal
What laboratory test is used to measure the clarity of wastewater?
✔✔Turbidity test
4
Study Guide Grade 1 Questions and
Answers | Latest Version | 2025/2026 |
Correct & Verified
What type of bacteria requires oxygen to survive and treat wastewater?
✔✔Aerobic bacteria
What is the main purpose of a primary clarifier?
✔✔To settle out suspended solids and reduce organic load
What is the main purpose of secondary treatment?
✔✔To biologically remove dissolved and colloidal organic matter
What is the typical pH of raw wastewater?
✔✔Between 6.5 and 8.5
What is the most common disinfectant used in wastewater treatment?
✔✔Chlorine
1
,What is the purpose of a digester in wastewater treatment?
✔✔To stabilize sludge and reduce pathogens
What is the main product of anaerobic digestion?
✔✔Methane gas
What is the primary goal of sludge thickening?
✔✔To reduce the volume of sludge by removing water
What is TSS in wastewater analysis?
✔✔Total Suspended Solids
What is the purpose of return activated sludge (RAS)?
✔✔To maintain an adequate population of microorganisms in the aeration tank
What is the main cause of septic conditions in wastewater?
✔✔A lack of dissolved oxygen
2
,What is the main purpose of chlorination in wastewater?
✔✔To kill or inactivate pathogens before discharge
What does FOG stand for in wastewater operations?
✔✔Fats, Oils, and Grease
What is the purpose of a flow equalization basin?
✔✔To balance fluctuations in influent flow and load
What is a common symptom of filamentous bacteria in activated sludge?
✔✔Bulking sludge with poor settling
What type of bacteria is responsible for nitrification?
✔✔Nitrifying bacteria such as Nitrosomonas and Nitrobacter
What is the main purpose of a bar screen?
✔✔To remove rags, sticks, and other large solids
3
, What is the main danger of high chlorine residual in effluent?
✔✔It is toxic to fish and aquatic life
What is the function of a grit chamber?
✔✔To remove heavy inorganic materials like sand and gravel
What happens when sludge is not removed regularly from a clarifier?
✔✔It can carry over into the effluent and reduce treatment efficiency
What is the main purpose of secondary clarifiers?
✔✔To settle out biological solids after aeration
What is sludge dewatering designed to accomplish?
✔✔To reduce the water content of sludge for easier handling and disposal
What laboratory test is used to measure the clarity of wastewater?
✔✔Turbidity test
4
