What is the sludge retention time in days for an aeration tank with 200,000 gallons and a flow rate of 1.5 MGD?

To determine the sludge retention time (SRT) in an aeration tank, you can use the formula that relates the volume of the tank to the flow rate. The sludge retention time is calculated by dividing the volume of the aeration tank by the flow rate in a compatible unit (gallons per day).

In this case, you have an aeration tank with a volume of 200,000 gallons and a flow rate of 1.5 million gallons per day (MGD), which is equivalent to 1,500,000 gallons per day.

Using the formula:

[ \text{SRT} = \frac{\text{Volume of the tank}}{\text{Flow rate}} ]

we can substitute in the provided values:

[ \text{SRT} = \frac{200,000 \text{ gallons}}{1,500,000 \text{ gallons/day}} ]

Calculating this gives:

[ \text{SRT} = \frac{200,000}{1,500,000} \text{ days} ]

[ \text{SRT} = 0.1333 \text{ days} ]

To find out the sludge retention time in days, we should