Wastewater Certification
Study Questions and
Complete Solutions
Graded A+
Denning [Date] [Course title]
, Floatable solids are easy to measure? (T/F) - Answer: False
A well operated digester receives sludge at _______ % volatile solids, and reduces it to about ______ %
volatile solids. - Answer: 70-75 %, 25-30%
According to OSHA, What is the lowest concentration of oxygen for humans to breath that is not
considered oxygen deficiency? - Answer: 21%
The population equivalency for BOD is... - Answer: .20 lb/day/BOD/person
What micro-organisms are found in good settling mixed liquor? - Answer: Rotifers, stalked ciliates, and
free swimming ciliates
What heavy metal is the most stringent for land application requirements? - Answer: Mercury
Why is sodium thiosulfate added to a microbiological sample? - Answer: To remove chlorine from the
sample
What is the disadvantage of using a constant percentage RAS flow control? - Answer: F/M varies more
than a constant rate RAS control
The outlet for a forced ventilation system for a chlorinator room should be located... - Answer: near the
floor
If packing is not maintained properly - Answer: Shaft or shaft sleeve will be damaged
Turbidity in wastewater is caused by... - Answer: Finely divided suspended material
What is the first action for a polymer spill? - Answer: Apply an absorbent to the spill such as sand or
kitty litter and then sweep up the material.