CH. 7 - ROTATING BIOLOGICAL CONTACTORS
QUESTIONS WITH DETAILED VERIFIED AND
100% ACCURATE ANSWERS
CH. 7 – ROTATING BIOLOGICAL CONTACTORS
Practice Examination with Verified Answers
SECTION 1: RBC FUNDAMENTALS AND BASIC CONCEPTS
Question 1
A Rotating Biological Contactor (RBC) is best described as:
A. A chemical treatment process
B. A secondary biological treatment process utilizing a rotating shaft surrounded
by plastic media discs
C. A tertiary treatment process only
D. A primary treatment addition
Answer: B
Explanation: An RBC is a secondary biological treatment process which utilizes a
rotating shaft surrounded by plastic media discs . RBCs utilize a fixed film media
system similar to a trickling filter .
Question 2
The microbial growth in an RBC secondary treatment process more closely
resembles the:
,A. MLSS in an activated sludge process
B. Feathery floc from an alum reaction
C. Heavy solids from a primary clarifier
D. Zoogleal slime from a trickling filter
Answer: D
Explanation: The biomass on RBC media is a zoogleal slime, similar to the
biological growth found on trickling filter media .
Question 3
What percentage of the RBC media surface is typically immersed in the
wastewater at any one time?
A. 20%
B. 40%
C. 60%
D. 80%
Answer: B
Explanation: About 40 percent of the media is submerged in the wastewater at
any one time .
Question 4
The rotating "drum" of the RBC unit that is defined as being the media from end
bearing to end bearing is called:
A. A train
B. The shaft
C. A bio-unit
D. A stage
Answer: B
,Explanation: The shaft supports and rotates the media when mechanical drives
are utilized. It simply supports the media when air drives are utilized .
Question 5
A series of RBC treatment units or "drums" lined up in a row, which take the flow
from the influent to the effluent is called:
A. Parallel flow
B. Stage groups
C. A series shaft
D. A train
Answer: D
Explanation: A series of RBC treatment units or "drums" lined up in a row, taking
flow from influent to effluent, is called a train .
Question 6
The excess growth on an RBC disc eventually falls off the media into the flow
stream and settles in the secondary clarifier. This process is referred to as:
A. Sloughing
B. Purging
C. Toxic shock
D. Bio-growth removal
Answer: A
Explanation: Sloughing is the term used to describe the process in which excess
microbial growth separates from the media and is washed to the secondary
clarifiers with the treated wastewater .
Question 7
The two types of RBC drive mechanisms are:
, A. Mechanical and electrical
B. Mechanical and air
C. Hydraulic and pneumatic
D. Manual and automatic
Answer: B
Explanation: There are two types of drive assemblies: mechanical drives and air
drives. A mechanical drive is attached directly to the shaft. An air drive consists of
deep plastic cups attached to the perimeter of the media, an air header, and an air
compressor .
Question 8
The typical maximum length of an RBC shaft is:
A. 15 feet
B. 20 feet
C. 27 feet
D. 35 feet
Answer: C
Explanation: The typical maximum shaft length is 27 feet long with a maximum of
25 feet occupied by media .
Question 9
The term used to describe uneven shaft rotation is:
A. Sloughing
B. Loping
C. Ponding
D. Bulking
Answer: B
QUESTIONS WITH DETAILED VERIFIED AND
100% ACCURATE ANSWERS
CH. 7 – ROTATING BIOLOGICAL CONTACTORS
Practice Examination with Verified Answers
SECTION 1: RBC FUNDAMENTALS AND BASIC CONCEPTS
Question 1
A Rotating Biological Contactor (RBC) is best described as:
A. A chemical treatment process
B. A secondary biological treatment process utilizing a rotating shaft surrounded
by plastic media discs
C. A tertiary treatment process only
D. A primary treatment addition
Answer: B
Explanation: An RBC is a secondary biological treatment process which utilizes a
rotating shaft surrounded by plastic media discs . RBCs utilize a fixed film media
system similar to a trickling filter .
Question 2
The microbial growth in an RBC secondary treatment process more closely
resembles the:
,A. MLSS in an activated sludge process
B. Feathery floc from an alum reaction
C. Heavy solids from a primary clarifier
D. Zoogleal slime from a trickling filter
Answer: D
Explanation: The biomass on RBC media is a zoogleal slime, similar to the
biological growth found on trickling filter media .
Question 3
What percentage of the RBC media surface is typically immersed in the
wastewater at any one time?
A. 20%
B. 40%
C. 60%
D. 80%
Answer: B
Explanation: About 40 percent of the media is submerged in the wastewater at
any one time .
Question 4
The rotating "drum" of the RBC unit that is defined as being the media from end
bearing to end bearing is called:
A. A train
B. The shaft
C. A bio-unit
D. A stage
Answer: B
,Explanation: The shaft supports and rotates the media when mechanical drives
are utilized. It simply supports the media when air drives are utilized .
Question 5
A series of RBC treatment units or "drums" lined up in a row, which take the flow
from the influent to the effluent is called:
A. Parallel flow
B. Stage groups
C. A series shaft
D. A train
Answer: D
Explanation: A series of RBC treatment units or "drums" lined up in a row, taking
flow from influent to effluent, is called a train .
Question 6
The excess growth on an RBC disc eventually falls off the media into the flow
stream and settles in the secondary clarifier. This process is referred to as:
A. Sloughing
B. Purging
C. Toxic shock
D. Bio-growth removal
Answer: A
Explanation: Sloughing is the term used to describe the process in which excess
microbial growth separates from the media and is washed to the secondary
clarifiers with the treated wastewater .
Question 7
The two types of RBC drive mechanisms are:
, A. Mechanical and electrical
B. Mechanical and air
C. Hydraulic and pneumatic
D. Manual and automatic
Answer: B
Explanation: There are two types of drive assemblies: mechanical drives and air
drives. A mechanical drive is attached directly to the shaft. An air drive consists of
deep plastic cups attached to the perimeter of the media, an air header, and an air
compressor .
Question 8
The typical maximum length of an RBC shaft is:
A. 15 feet
B. 20 feet
C. 27 feet
D. 35 feet
Answer: C
Explanation: The typical maximum shaft length is 27 feet long with a maximum of
25 feet occupied by media .
Question 9
The term used to describe uneven shaft rotation is:
A. Sloughing
B. Loping
C. Ponding
D. Bulking
Answer: B
