In the activated-sludge process, return activated sludge is recycled mainly to:
Correct answer: C. Maintain a sufficient population of microorganisms in the aeration tank
- A. Prevent oxygen transfer in the aeration tank
- B. Increase the amount of grit entering the primary clarifier
- C. Maintain a sufficient population of microorganisms in the aeration tank
- D. Convert treated effluent into drinking water
Explanation
Return sludge brings active microorganisms from the secondary clarifier back to the aeration tank. This maintains the biological solids concentration needed to break down organic matter.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? support@testustad.com
About Environmental Engineering
Environmental engineering examines water supply, water quality, treatment processes, wastewater collection and treatment, solid waste management, air pollution and public health protection. It covers sedimentation, coagulation, filtration, disinfection, biological treatment and disposal methods, while distinguishing drinking-water treatment from sewage treatment and BOD from COD.
Practise Environmental Engineering
80 free Environmental Engineering MCQs from Civil Engineering, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Civil Engineering questions like this
Civil Engineering is on 3 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Environmental Engineering questions
The primary public-health objective of chlorination in drinking-water treatment is to:
In a conventional water-treatment plant, rapid sand filtration is mainly used after coagulation and sedimentation to remove:
Which contaminant is most directly removed by a properly designed sedimentation basin?
Which treatment stage primarily removes settleable solids from domestic sewage before biological treatment?
Which feature is essential for reducing groundwater contamination at a modern sanitary landfill?
An electrostatic precipitator is primarily used in air-pollution control to remove: