Question

It is desired to convert from slow sand filters to high-rate filters. The slow sand filters operate at a rate of 10 million gallons/acre-day and have a total area of 15 acres. Assuming the high-rate filters are rated for 6 gpm/ft2, and each filter has an area of 1,000 ft2, how many filters are required

Answer 1

Total 17 high rate filters are required

Explanation:

Given -

Rate of filtration of slow sand filters = 10 million gallons/acre-day

Total million gallons of water filtered per day = 10 million gallons/acre-day * 15 acres

= 150 Million gallons per day

Rate of filtration of high rate filters = 6 gpm/ft2

Area of one high rate filter = 1,000 ft2

Volume of water filtered by 1 high rate filter is 6 gpm/ft2 *1,000 ft2 = 6000 gallons per minute = 8640000 gallon per day

Number of filters required = 150 million gallons per day /8640000 gallon per day

150 * 10^6/8640000

17

Total 17 high rate filters are required