What is the filter rate in gpm/ft² for an 8 MGD plant with 4 filters measuring 20 feet wide and 30 feet long?

To compute the filter rate in gallons per minute per square foot (gpm/ft²) for the water treatment plant, we begin by determining the total surface area of all the filters and the flow rate of the plant.

First, convert the flow rate from million gallons per day (MGD) to gallons per minute (gpm):

1 MGD = 1,000,000 gallons per day

So, 8 MGD equals:

[

8 \times 1,000,000 = 8,000,000 \text{ gallons/day}

]

Next, to convert this daily flow rate to gallons per minute, divide by the number of minutes in a day (1,440 minutes):

[

\frac{8,000,000 \text{ gallons}}{1,440 \text{ minutes}} \approx 5,555.56 \text{ gpm}

]

Now, calculate the surface area of one filter. Each filter is 20 feet wide and 30 feet long:

[

\text{Area of one filter} = \text{width} \times \text{length} = 20 \text{ ft} \times 30 \text{ ft} =