Detention Time Given Discharge Calculator

Detention Time Formula:

\[ T_d = \frac{w \times L \times d}{Q} \]

Width (w):

Length (L):

Depth (d):

Discharge (Q):

m³/s

Detention Time (Td):

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1. What is Detention Time?

Detention Time is the length of time the water is retained in a vessel or basin. It represents the average time that a fluid particle remains in a treatment unit.

2. How Does the Calculator Work?

The calculator uses the Detention Time formula:

\[ T_d = \frac{w \times L \times d}{Q} \]

Where:

\( T_d \) — Detention Time (seconds)
\( w \) — Width of the vessel or basin (meters)
\( L \) — Length of the vessel or basin (meters)
\( d \) — Depth of the vessel or basin (meters)
\( Q \) — Discharge or flow rate (cubic meters per second)

Explanation: The formula calculates the time required for a volume of fluid to pass through a treatment unit based on the physical dimensions of the unit and the flow rate.

3. Importance of Detention Time Calculation

Details: Proper detention time is crucial for effective water and wastewater treatment processes. It ensures sufficient contact time for physical, chemical, and biological processes to occur, such as sedimentation, coagulation, and disinfection.

4. Using the Calculator

Tips: Enter all dimensions in meters, discharge in cubic meters per second. All values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: Why is detention time important in treatment processes?
A: Adequate detention time ensures that treatment processes have sufficient time to work effectively, whether it's for sedimentation, chemical reactions, or biological treatment.

Q2: What are typical detention times for different treatment processes?
A: Detention times vary widely: sedimentation basins (2-4 hours), activated sludge (4-8 hours), chlorine contact tanks (30-60 minutes), depending on the specific treatment objectives.

Q3: How does detention time affect treatment efficiency?
A: Too short detention time may result in incomplete treatment, while too long detention time can lead to unnecessary large basins and increased costs.

Q4: Can detention time be too long?
A: Yes, excessive detention time can lead to problems such as septic conditions, loss of disinfectant residual, or unnecessary capital and operational costs.

Q5: How is detention time related to flow rate?
A: Detention time is inversely proportional to flow rate - as flow rate increases, detention time decreases, and vice versa, assuming constant basin volume.