Wastewater Class A/1 Certification Practice Exam Study
Guide: 2026–2027 Updated Edition with Comprehensive
Practice Questions and Verified Answers
Who can obtain a Class A or Class 1 without testing? - Answer - if you get a
reciprocity from another state or are given a provisional license
If a mechanical bar screen becomes plugged what is the first thing you should do? -
Answer - Tell the operator then Lockout/tag out and divert flow.
Why is grit removal important? - Answer - Wear and tear on equipment as well as
taking up valuable space
what does a comminutor do? - Answer - shred
What is detritus? - Answer - a mixture of grit (non-organic material) and organic
material
Pipette measurements are measured from where? - Answer - the bottom of the
meniscus
Pipettes are used for what types of measuring? - Answer - When more accuracy is
needed, used to deliver chemicals
If an outcome of a sample changes, What could be the cause? - Answer -
continuing bio activity, improper preservation
Grab sample examples - Answer - pH, temperature, bacterial, chlorine, volatile
organics, cyanide
, What is the first gas to develop in a new anaerobic digester? - Answer - carbon
dioxide
Gas Chlorinator is having issues. the problems are: the maximum feed rate not
being reached, injector water low at high feed rate, injector water supply pressure
normal, injector vacuum stays low with low feed rate - Answer - injector clogged
what action should be performed if there are streaks of sludge on the belt filter
press? - Answer - clean the wash box nozzles
What is mixed liquor solids? - Answer - the amount of suspended solids in an
aeration tank, this measurement is expressed in milligrams per liter
what is return activated sludge? - Answer - its to prevent loss of microorganisms
from aeration tank and maintain an adequate population for treatment of the
wastewater.
Return flow rate can be determined through? - Answer - observation, Solids mass
balance equation, or the settleability criteria
Why is sludge wasting important in an activated sludge system? - Answer -
Because more activated sludge is produced that what is needed, requiring the
excess sludge to be wasted to keep the F/M ratio in an ideal range based on each
facility.
what is the expected sludge age in an extended aeration system? - Answer - it'll be
older sludge between 15-30 days
Guide: 2026–2027 Updated Edition with Comprehensive
Practice Questions and Verified Answers
Who can obtain a Class A or Class 1 without testing? - Answer - if you get a
reciprocity from another state or are given a provisional license
If a mechanical bar screen becomes plugged what is the first thing you should do? -
Answer - Tell the operator then Lockout/tag out and divert flow.
Why is grit removal important? - Answer - Wear and tear on equipment as well as
taking up valuable space
what does a comminutor do? - Answer - shred
What is detritus? - Answer - a mixture of grit (non-organic material) and organic
material
Pipette measurements are measured from where? - Answer - the bottom of the
meniscus
Pipettes are used for what types of measuring? - Answer - When more accuracy is
needed, used to deliver chemicals
If an outcome of a sample changes, What could be the cause? - Answer -
continuing bio activity, improper preservation
Grab sample examples - Answer - pH, temperature, bacterial, chlorine, volatile
organics, cyanide
, What is the first gas to develop in a new anaerobic digester? - Answer - carbon
dioxide
Gas Chlorinator is having issues. the problems are: the maximum feed rate not
being reached, injector water low at high feed rate, injector water supply pressure
normal, injector vacuum stays low with low feed rate - Answer - injector clogged
what action should be performed if there are streaks of sludge on the belt filter
press? - Answer - clean the wash box nozzles
What is mixed liquor solids? - Answer - the amount of suspended solids in an
aeration tank, this measurement is expressed in milligrams per liter
what is return activated sludge? - Answer - its to prevent loss of microorganisms
from aeration tank and maintain an adequate population for treatment of the
wastewater.
Return flow rate can be determined through? - Answer - observation, Solids mass
balance equation, or the settleability criteria
Why is sludge wasting important in an activated sludge system? - Answer -
Because more activated sludge is produced that what is needed, requiring the
excess sludge to be wasted to keep the F/M ratio in an ideal range based on each
facility.
what is the expected sludge age in an extended aeration system? - Answer - it'll be
older sludge between 15-30 days
