What is detention time of a tank?
The actual or theoretical (calculated) time required for water to fill a tank at a given flow; pass through a tank at a given flow; or remain in a settling basin, flocculating basin, rapid-mix chamber, or storage tank.
What is detention time in wastewater treatment?
Detention Time Definitions: The theoretical (calculated) time required for a given amount of water or wastewater to pass through a tank at a given rate of flow. The time required to fill a tank at a given flow.
What are the detention times for different tanks in wastewater treatment?
The detention period adopted for sewage sedimentation tanks is of the order of:
- 1 – 2 hours.
- 4 – 8 hours.
- 8 – 16 hours.
- 24 – 36 hours.
What is detention time?
Detention Time is the amount of time it takes for a molecule of water to travel a certain distance. In a sedimentation basin it is the time it takes for a particle to travel across the basin. Water treatment operators calculate detention times for settling basins, flocculation basins, or rapid mixing chambers.
How do you find detention time?
Detention time is calculated by dividing the volume of the tank or basin by the flow rate. It’s fairly simple and straight-forward. The most challenging part of calculating detention time is making sure the units on the top and bottom of the formula cancel out.
What is the detention time of wastewater in the tank without sludge accumulation?
Detention time (the time it takes to fill the tank) ranges from 1 to 6 hours, depending on the design of the basin. A short circuit is the flowing of incoming water through the tank, without proper stratification of the water in the basin.
What is the difference between retention time and detention time?
Detention and retention both refer to storing rain water on-site during a storm event, when the risk of flooding is highest. The difference is that when water is detained, it is slowly released into a stream or river and leaves the site. When water is retained, it is not intended to leave the site.
What is the detention time in each clarifier?
For both water and wastewater treatment, the detention time for clarifiers is usually in the range of 2 to 3 hours. The reason why the flow spends a long time in the clarifier is to enable the solids to settle to the bottom. Otherwise, you’ll see more solids in the effluent of the clarifier.
How is tank residence time calculated?
By definition, the residence time is the amount of material in the reservoir, divided by either the inflow or the outflow (they are equal when the reservoir is at equilibrium). If there are multiple inflows or outflows, then we use the sum of the outflows or inflows to determine the residence time.
What is hydraulic detention time?
Hydraulic detention time (HDT) also known as hydraulic retention time (HRT) is a measure of the average length of time that a compound (in this case wastewater) remains in a treatment tank or unit.