A rapid sand filter has a loading rate of 8.00 m/h, surface dimensions of 10 m ' 8 m, an effective filtration rate of 7.70 m/h. A complete filter cycle duration is 52 h and the filter is rinsed for 20 minutes at the start of each cycle. a. What flow rate (m3 / s) does the filter handle during production? b. What volume of water is used for backwashing plus rinsing the filter in each filter cycle?

given data

loading rate = 8.00 m/h

filtration rate = 7.70 m/h

dimensions = 10 m * 8 m

filter cycle duration = 52 h

time = 20 min

to find out

flow rate and volume of water is used for back washing plus rinsing the filter

solution

we consider here production efficiency is 96%

so here flow rate will be

flow rate = area * rate of filtration

flow rate = 10 * 8 * 7.7

flow rate = 616 m³/h

and

we know back washing generally 3 to 5 % of total volume of water per cycle so

volume of water is = 616 * 52

volume of water is 32032 m³

and

volume of water of back washing is = 4% of 32032

volume of water of back washing is 1281.2 m³