Question

A filter 30 feet (ft) long by 12 ft wide treats a flow of 4.4 million gallons per day (MGD). What is the filtration rate in gpm/ft2?1) 1.2 gpm/ft^2.

2) 81.8 gpm/ft^2.
3) 3,055.6 gpm/ft^2.
4) 8.5 gpm/ft^2.

Answer 1

(4) 8.5 gpm/ft²

Step-by-step explanation:

Given;

length of the filter, L = 30 ft

width of the filter, w = 12 ft

the filtration rate, Q = 4.4 x 10⁶ GPD

Area of the filter; A = 30 ft x 12 ft = 360 ft²

The filtration rate in gallon per minutes (gpm) is calculated as;

`Q = 4.4 * 10^6 \ ((gallon)/(day) * (1 \ day)/(24 \ hours) * (1 \ hour)/(60 \min) ) = 3,055.556 \ gpm`

The filtration rate in gallon per minutes per feet squared (gpm/ft²) is calculated as;

`Q = (3,055.556 \ gpm)/(360 \ ft^2) = 8.49 \ (gpm)/(ft^2) \ = \ 8.5 \ (gpm)/(ft^2)`

Therefore, the filtration rate in gpm/ft² is 8.5 gpm/ft²