Wastewater Treatment Grade 1 Exam
Questions with Answers
Why would sodium bicarbonate or lime be added to an anaerobic digester?
A) To neutralize high acid production
B) To decrease alkalinity
C) To decrease the ph
D) To decrease volatile reduction - ✔✔A) To neutralize high acid production
What is the term for a liquid or sludge with a ph of 6.0?
A) Alkaline
B) Neutral
C) Basic
D) Acidic - ✔✔D) Acidic
What are the two basic types of lime that can be used in the lime stabilization process?
A) Hard lime and soft lime
B) Quicklime and hydrate lime
C) Limestone and pebble lime
D) Calcium hydroxide and ferric chloride - ✔✔B) Quicklime and hydrate lime
What factor may be more important in maintaining efficient operation of a primary clarifier?
A) Location of the tank
B) Characteristics of the influent wastewater
C) Number of operators in the facility
D) Activated sludge SRT - ✔✔B) Characteristics of the influent wastewater
,What device is designed to protect the anaerobic digester tanks and covers from damage?
A) Hot water system
B) Pressure/Vacuum relief
C) Gas recirculation
D) Drip trap - ✔✔B) Pressure/Vacuum relief
Which test indicates the amount of time it takes for sludge particles to float to the surface in
the DAF process?
A) Rise Rate
B) D.O.
C) Centrifuge spin down
D) Microscopic exam - ✔✔A) Rise Rate
What may be the better method of removing primary sludge from a clarifier?
A) Large volumes only a few times each day
B) Small volumes one each day
C) Small volumes several times throughout the day
D) When the blanket gets 1 foot from the weir - ✔✔C) Small volumes several times throughout
the day
Which group of bacteria are most responsible for removal of phosphorus in the BNR activated
sludge process?
A) SVI
B) GSA
C) Autotrophic
D) PAO - ✔✔D) PAO
, Which group of bacteria is responsible for conversion of inorganic ammonia in wastewater?
A) Carbon eaters
B) Methanogens
C) Autotrophic
D) Heterotrophic - ✔✔C) Autotrophic
What is a common ph range in a properly operated aerobic digester?
A) 7.5-8.5
B) 6.8-7.2
C) 5.8-6.2
D) 8.2-9.1 - ✔✔B) 6.8-7.2
What is the principle concept of a centrifuge?
A) Dewaters through pressure shearing
B) Thickens through gravity drainage
C) Thickens through high-speed spinning
D) Thickens through pressure filtration. - ✔✔C) Thickens through high-speed spinning
What does a closed circuit mean in electrical terms?
A) That power is disengaged... Dead
B) That the power is off
C) That power is engaged.... Live
D) The term "closed" has nothing to do with electricity - ✔✔C) That power is engaged.... Live
What would be an unacceptable surface loading rate for a primary clarifier?
A) 400-600 GPD
B) 800-1,200 GPD
Questions with Answers
Why would sodium bicarbonate or lime be added to an anaerobic digester?
A) To neutralize high acid production
B) To decrease alkalinity
C) To decrease the ph
D) To decrease volatile reduction - ✔✔A) To neutralize high acid production
What is the term for a liquid or sludge with a ph of 6.0?
A) Alkaline
B) Neutral
C) Basic
D) Acidic - ✔✔D) Acidic
What are the two basic types of lime that can be used in the lime stabilization process?
A) Hard lime and soft lime
B) Quicklime and hydrate lime
C) Limestone and pebble lime
D) Calcium hydroxide and ferric chloride - ✔✔B) Quicklime and hydrate lime
What factor may be more important in maintaining efficient operation of a primary clarifier?
A) Location of the tank
B) Characteristics of the influent wastewater
C) Number of operators in the facility
D) Activated sludge SRT - ✔✔B) Characteristics of the influent wastewater
,What device is designed to protect the anaerobic digester tanks and covers from damage?
A) Hot water system
B) Pressure/Vacuum relief
C) Gas recirculation
D) Drip trap - ✔✔B) Pressure/Vacuum relief
Which test indicates the amount of time it takes for sludge particles to float to the surface in
the DAF process?
A) Rise Rate
B) D.O.
C) Centrifuge spin down
D) Microscopic exam - ✔✔A) Rise Rate
What may be the better method of removing primary sludge from a clarifier?
A) Large volumes only a few times each day
B) Small volumes one each day
C) Small volumes several times throughout the day
D) When the blanket gets 1 foot from the weir - ✔✔C) Small volumes several times throughout
the day
Which group of bacteria are most responsible for removal of phosphorus in the BNR activated
sludge process?
A) SVI
B) GSA
C) Autotrophic
D) PAO - ✔✔D) PAO
, Which group of bacteria is responsible for conversion of inorganic ammonia in wastewater?
A) Carbon eaters
B) Methanogens
C) Autotrophic
D) Heterotrophic - ✔✔C) Autotrophic
What is a common ph range in a properly operated aerobic digester?
A) 7.5-8.5
B) 6.8-7.2
C) 5.8-6.2
D) 8.2-9.1 - ✔✔B) 6.8-7.2
What is the principle concept of a centrifuge?
A) Dewaters through pressure shearing
B) Thickens through gravity drainage
C) Thickens through high-speed spinning
D) Thickens through pressure filtration. - ✔✔C) Thickens through high-speed spinning
What does a closed circuit mean in electrical terms?
A) That power is disengaged... Dead
B) That the power is off
C) That power is engaged.... Live
D) The term "closed" has nothing to do with electricity - ✔✔C) That power is engaged.... Live
What would be an unacceptable surface loading rate for a primary clarifier?
A) 400-600 GPD
B) 800-1,200 GPD
