This set of Waste Water Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Activated Sludge Process – 1”.
1. Activated sludge process uses micro-organisms to degrade organics from wastewater.
a) True
b) False
View Answer
Explanation: An activated sludge process refers to a multi-chamber reactor unit that makes use of highly concentrated micro-organisms to degrade organics and remove nutrients from wastewater to produce a high quality effluent.
2. Activated sludge process degrade organics and _________
a) Improve nutrients
b) Remove nutrients
c) Remove odour
d) Remove taste
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Explanation: Highly concentrated micro-organisms are used to degrade organics and remove nutrients from wastewater to produce a high quality effluent that is activated sludge process.
3. What is required to keep the activated sludge suspended?
a) Carbon-dioxide
b) Nitrogen
c) Oxygen
d) Ammonia
View Answer
Explanation: To maintain the aerobic conditions and to keep the activated sludge suspended, a continuous and well-timed supply of oxygen is required. Flocs of bacteria, which are suspended and mixed with wastewater is used for the process.
4. What does the bacterium use to grow?
a) Oxygen
b) Organic pollutants
c) Water
d) Carbon-dioxide
View Answer
Explanation: The bacteria use the organic pollutants to grow and transform it to energy, water, carbon-dioxide and new cell material. The bacterium is present in the form of flocs which are suspended and mixed with wastewater.
5. Activated sludge process can be used for treating all types of wastewater.
a) True
b) False
View Answer
Explanation: Activated sludge systems are suspended-growth type and are used in conventional high-tech wastewater treatment plants to treat almost every wastewater influent as long as it is biodegradable.
6. ________ combines aeration basin and secondary clarifier into single unit.
a) Primary clarifier
b) Aerobic unit
c) Sequential batch reactor
d) Secondary clarifier
View Answer
Explanation: An SBR essentially combines the aeration basin and the secondary clarifier of a traditional activated sludge system into a single basin. While the system is in aeration mode, air is supplied by the aeration system and influent enters the basin.
7. What does SBR stand for?
a) Secondary batch reactor
b) Sequential biological reactor
c) Secondary biological reactor
d) Sequential batch reactor
View Answer
Explanation: SBR stands for a Sequential batch reactor. An SBR essentially combines the aeration basin and the secondary clarifier of a traditional activated sludge system into a single basin.
8. SBR operates as ________ process.
a) Batch
b) Continuous
c) Semi-continuous
d) Discontinuous
View Answer
Explanation: SBR operates as a batch process. Because sequential batch reactors operate as a batch process, the level of the basin starts out low and the basin fills over several hours as influent enters.
9. When the aeration system shuts off, the basin begins to perform as a ______
a) Primary clarifier
b) Secondary clarifier
c) Anaerobic unit
d) Aeration unit
View Answer
Explanation: When the filling/ aeration phase is complete, the aeration system shuts off and the basin begins to function as a secondary clarifier. Suspended solids and micro-organisms settle to the bottom of the tank and clarified water is left near the surface.
10. _______ provides the dual purpose of providing DO and mixing of the mixed liquor and wastewater.
a) Flocculation
b) Aeration
c) Sedimentation
d) Clarification
View Answer
Explanation: Aeration serves the dual purpose of providing dissolved oxygen and mixing of the mixed liquor and wastewater in the aeration tank. Two methods are commonly used to disperse oxygen from the air to the micro-organisms; Surface Aeration and Diffused Aeration.
Sanfoundry Global Education & Learning Series – Waste Water Engineering.
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