Question 1
______ is removed by Anammox.
A. Nitric oxides
B. Nitrate
C. Nitrite
D. Ammonia
View Answer
Answer: Option D
Explanation:
An anaerobic process uses anoxic methods to remove ammonia, such as the removal of ammonia via Anammox or the study of slow-growing micro-organisms.
Question 2
______ is used to remove phosphorus compounds from the liquor.
A. Aluminium nitrate
B. Aluminium phosphate
C. Aluminium sulphate
D. Sodium nitrate
View Answer
Answer: Option C
Explanation:
To remove phosphorus compounds from the liquor, aluminium sulphate (alum) is often added during this period. It reacts to form non-soluble compounds, which settle into the sludge in the next stage.
Question 3
___________ helps to mix the incoming influent and the returned activated sludge.
A. Walls
B. Orifice
C. Manifold
D. Bio-selector
View Answer
Answer: Option D
Explanation:
This helps to mix the incoming Influent and the returned activated sludge (RAS), beginning the biological digestion process before the liquor enters the main part of the tank.
Question 4
Bio-selectors direct the flow.
A. True
B. False
View Answer
Answer: Option A
Explanation:
In some systems, tanks contain a section known as the bio-selector, which consists of a series of walls or baffles which direct the flow either from side to side of the tank or under and over consecutive baffles.
Question 5
BOD is a physical procedure for determining DO needed for aerobic biological organisms.
A. True
B. False
View Answer
Answer: Option B
Explanation:
BOD is a chemical procedure for determining the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material.
Question 6
How is mixing done in SBR?
A. Manual
B. Mechanical
C. Air stripping
D. Agitation by air
View Answer
Answer: Option B
Explanation:
The inlet valve opens and the tank is being filled in, while mixing is provided by mechanical means (no air). This stage is also called the anoxic stage.
Question 7
How many types of BOD are present?
A. 1
B. 2
C. 3
D. 4
View Answer
Answer: Option B
Explanation:
BOD can be used as a gauge of the effectiveness of wastewater treatment plants. It is listed as a conventional pollutant in the U.S. Clean Water Act. The two major types of BOD are soluble BOD and insoluble BOD.
Question 8
In which stage are the aeration and mixing avoided?
A. First
B. Second
C. Third
D. Fourth
View Answer
Answer: Option C
Explanation:
No aeration or mixing is provided in the third stage and the settling of suspended solids starts. During the fourth stage, the outlet valve opens and the “clean” supernatant liquor exits the tank.
Question 9
In which stage of the SBR is aeration performed?
A. First
B. Second
C. Third
D. fourth
View Answer
Answer: Option B
Explanation:
The fixed or floating mechanical pumps are used or air is transferred into fine bubble diffusers fixed to the floor of the tank during the second stage aeration of the mixed liquor.
Question 10
SBR is a type of ________
A. Aerobic process
B. Activated sludge process
C. Anaerobic process
D. Chemical process
View Answer
Answer: Option B
Explanation:
Sequencing batch reactors (SBR) or sequential batch reactors are a type of activated sludge process for the treatment of wastewater. SBR reactors treat wastewater such as sewage or output from anaerobic digesters or mechanical biological treatment facilities in batches.
Question 11
The _________ is usually the same length in time as the aeration.
A. Screening stage
B. Mixing stage
C. Clarification stage
D. Settling stage
View Answer
Answer: Option D
Explanation:
The settling stage is usually the same length in time as the aeration and during this stage, the sludge formed by the bacteria is allowed to settle to the bottom of the tank.
Question 12
The one tank is aerating and filling while the other one is decant.
A. True
B. False
View Answer
Answer: Option A
Explanation:
The tanks have a “flow through” system, with raw wastewater (influent) coming in at one end and treated water (effluent) flowing out of the other. One tank is in settle/decant mode the other is aerating and filling in multiple tank systems.
Question 13
The multiplication of _________ is encouraged by the addition of oxygen.
A. Bacteria
B. Aerobic bacteria
C. Anaerobic bacteria
D. Fungi
View Answer
Answer: Option B
Explanation:
Aeration times vary according to the plant size and the composition/quantity of the incoming liquor, but are typically 60 to 90 minutes. The multiplication of aerobic bacteria is encouraged by the addition of oxygen.
Question 14
Which part of the tank is suitable for anaerobic bacteria to flourish?
A. Top
B. Bottom
C. Sides
D. Middle zone
View Answer
Answer: Option B
Explanation:
The aerobic bacterium multiplies until the dissolved oxygen is all used up. The bottom conditions are more suited for the anaerobic bacteria to flourish.