Grit chambers are typically designed with a detention period averaging_______________?
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Answer: A. 1 minute
Explanation
Grit chambers use short detention periods to target heavy inorganic particles specifically. An average detention time of one minute prevents lighter organic solids from settling out. Fast flow-through rates keep organic matter suspended while allowing dense sand to drop. Grit consists of heavy inorganic materials such as sand, gravel, and coffee grounds. Detention time refers to the average length of time water remains inside the treatment unit. Hydraulic design controls horizontal velocity to maintain approximately zero point three meters per second.
Removing grit protects downstream pumps and mechanical equipment from abrasive wear and tear. Municipal treatment plants install grit chambers near the headworks before primary sedimentation basins. Effective grit removal prevents pipeline blockages and accumulation in primary digestion tanks. Five minutes would allow excessive organic solids to settle alongside the heavy mineral grit. Two to four hours represents the typical detention period for standard primary sedimentation tanks. Twelve hours is an extremely long duration typically reserved for specialized biochemical digestion stages.
- Subject
- Engineering
- Category
- Civil Engineering
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- —
- Difficulty
- medium
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