WASTEWATER TREATMENT OPERATOR CERTIFICATION EXAM 200 QUESTIONS AND

WASTEWATER TREATMENT OPERATOR CERTIFICATION EXAM 200 QUESTIONS AND

WASTEWATER TREATMENT OPERATOR CERTIFICATION

EXAM 2026-2027 200 QUESTIONS AND

CORRECT DETAILED ANSWERS WITH

RATIONALES

Digester gas is_______when mixed with air the the proper proportions -

ANSWER- extremely explosive

Wastewater Treatment Facilities:

A pond that is used to treat raw wastewater is called - ANSWER- a

waste stabilization pond

Wastewater Treatment Facilities:

A pond that has an aerobic top layer and an anaerobic bottom layer is

called - ANSWER- a facultative pond

Preliminary Treatment:

What is the angle of the bars on a manually cleaned bar screen? -

ANSWER- 30 degrees

Preliminary Treatment:

What is the angle of the bards on a mechanically cleaned bar screen -

ANSWER- 45-60 degrees

Preliminary Treatment:

What is the ideal wastewater velocity in FPS through a screen channel? -

ANSWER- 1.5ft/s

Preliminary Treatment:

What is the ideal wastewater velocity in FPS for grit removal in a grit

chamber - ANSWER- 1.0 ft/s

Preliminary Treatment:

In general, what is the water content of screen material - ANSWER80%

Preliminary Treatment:

What is the wastewater velocity range in FPS for grit removal in a grit

chamber? - ANSWER- 0.7 - 1.4 ft/s

Racks, screens, comminutors and Grit removal:

Which one of the following chemicals gives water its greatest capacity

to neutralize acids? - ANSWER- hydroxide

Racks, screens, comminutors and Grit removal:

The bar rack is used - ANSWER- when the bar screen is out of service

Primary Sedimentation:

Typically, what is the average detention time for wastewater in a

primary clarifier? - ANSWER- 2 hr

Sedimentation and Flotation:

Name one gas this irritates the "eyes" - ANSWER- chlorine

Primary Sedimentation:

Activated sludge clarifiers accept material to be settled from -

ANSWER- an aeration tank

Primary Sedimentation:

According to CWA, secondary treatment is defines as a wastewater plant

producing an effluent that has no more than____total suspended solids

and no more than_____BOD5 - ANSWER- 30 mg/L, 30 mg/L

Primary Sedimentation:

The color of bio film on a rotating Biological Contactor would

appear____under normal operating conditions - ANSWER- gray

Activated Sludge:

A primary effluent and returned activated sludge mixture is called -

ANSWER- waste activated sludge

Activated Sludge:

The mixture of organisms and solids in water that is removed from the

settling tank is called - ANSWER- mixed liquor

Activated Sludge:

Under normal operating conditions, what color is activated sludge -

ANSWER- dark chocolate brown

Activated Sludge: