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Detention time refers to the length of time water is retained in a vessel or basin. It is a critical parameter in sedimentation tank design and operation, determining how long particles have to settle out of the water column.
The calculator uses the formula:
Where:
Explanation: The formula calculates detention time by dividing the flowing through period by the displacement efficiency, which represents the ratio of flowing period to detention period.
Details: Accurate detention time calculation is crucial for proper sedimentation tank design, ensuring sufficient time for particles to settle and optimizing treatment efficiency in water and wastewater treatment systems.
Tips: Enter flowing through period in seconds and displacement efficiency (unitless). Both values must be positive numbers greater than zero for accurate calculation.
Q1: What is displacement efficiency?
A: Displacement efficiency is the ratio of flowing period to detention period, indicating how effectively water moves through the sedimentation tank.
Q2: Why is detention time important in sedimentation tanks?
A: Proper detention time ensures that suspended particles have sufficient time to settle out of the water, improving treatment efficiency and water quality.
Q3: What factors affect detention time?
A: Tank volume, flow rate, tank geometry, and inlet/outlet configurations all influence the actual detention time in a sedimentation tank.
Q4: How does detention time relate to settling efficiency?
A: Longer detention times generally allow more particles to settle, but there's an optimal range beyond which additional time provides diminishing returns.
Q5: What are typical detention times for sedimentation tanks?
A: Detention times typically range from 2-4 hours for primary sedimentation and 4-8 hours for secondary sedimentation in wastewater treatment plants.