If a grit chamber has a design flow velocity of 0.2 m/sec and a detention period of 2 minutes, what is its required length__________________?
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Answer: C. 24 m
Explanation
Required length equals the product of design flow velocity and the specified detention time duration. Multiplying 0.2 meters per second by 120 seconds yields a total calculated chamber length of 24 meters. This dimensional calculation ensures grit particles have sufficient horizontal travel time to settle out. Grit chambers remove heavy inorganic sand and gravel to protect mechanical equipment from abrasive wear. Detention period represents the average time a given wastewater volume remains inside the treatment tank. Maintaining controlled horizontal velocities prevents organic matter from settling alongside heavier grit particles.
Municipal sewage treatment plants utilize grit removal channels at the headworks of every facility. Properly sized grit chambers prevent pipeline blockages and pump impeller damage throughout the plant. Environmental engineers design these basins to handle peak hourly wet-weather stormwater flow surges. A length of 16 meters underestimates the required settling distance for the given velocity and time. A length of 20 meters results from incorrect time conversion math during preliminary sizing calculations. A length of 30 meters exceeds the required dimensions, leading to unnecessary construction and land costs.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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