Filtration
Filtration Rate - 1
FIRST. Read the question CAREFULLY and look for KEY WORDS to help you decide what formula to use.
A sand filtration basin measures 30 ft wide by 40 ft long with a flow of 5.5 MGD. What is the filtration rate in GPM/ft2?
SECOND. By using the KEY WORDS you see this is a (Filtration) problem, that includes (gallons per minute).
The Formula (F) and Conversions & Calculations (C&C) shown below.
Gal/day = MGD x 1,000,000 (C&C)1
Area, Ft2 = Length x Width (C&C)2
Filter Rate (GPM/ft2) = Gallons per Day (F)3
Area,Ft2 x 1,440 min/day
THIRD. Follow the solution procedure above to solve the problem!
5.5 MGD x 1,000,000 = 5,500,000 gal
40 ft x 30 ft = 1,200 ft2
5,500,000 gal = 5,500,000 gal = 3.18 GPM/ft2
1,200 Ft2 x 1,440 1,728,000
Loading Rate - 1
FIRST. Read the question CAREFULLY and look for KEY WORDS to help you decide what formula to use.
What is the hydraulic loading rate for a filter that is 600 ft2 with a flow rate of 2,400 GPM/ft2?
SECOND. By using the KEY WORDS you see this is a (Filtration) problem, that includes (loading rate).
The Formula (F) and Conversions & Calculations (C&C) shown below.
Loading Rate (GPM/ft2) = Gallons per Minute (F)
Area,ft2
THIRD. Follow the solution procedure above to solve the problem!
2,400 GPM = 4 GPM/ft2
600 ft2
Daily Filter Production - 1
FIRST. Read the question CAREFULLY and look for KEY WORDS to help you decide what formula to use.
A sand filtration basin measures 70 long ft by 50 ft wide with a flow of 4 gallons per minute/ft2. What is the daily filter production in gallons per day?
SECOND. By using the KEY WORDS you see this is a (Filtration) problem, that includes (gallons per day).
The Formula (F) and Conversions & Calculations (C&C) shown below.
Area, Ft2 = Length x Width (C&C)1
Daily Filter Production(GPD) = Filter,ft2 x GPM/ft2 x 1,440 min/day (F)2
THIRD. Follow the solution procedure above to solve the problem!
70 ft x 50 ft = 3,500 ft2
3,500 ft2 x 4 gpm/ft2 x 1,440 min/day = 20,160,000 gpd
Backwash Pumping Rate - 1
FIRST. Read the question CAREFULLY and look for KEY WORDS to help you decide what formula to use.
You’ve been sent to backwash your sedimentaion basin with a flow of 13 GPM/ft2, the basin is 45 ft long and 25 ft wide. What is the backwash pumping rate in gallons per minute?
SECOND. By using the KEY WORDS you see this is a (Filtration) problem, that includes (backwash pump rate).
The Formula (F) and Conversions & Calculations (C&C) shown below.
Area, Ft2 = Length x Width (C&C)1
Backwash Pump Rate(GPM) = Filter,ft2 x Backwash Rate, GPM/ft2 (F)2
THIRD. Follow the solution procedure above to solve the problem!
45 ft x 25 ft = 1,125 ft2
1,125 ft2 x 13 GPM/ft2 = 14,625 GPM
Backwash Volume - 1
FIRST. Read the question CAREFULLY and look for KEY WORDS to help you decide what formula to use.
A sand filtration basin is 65 ft long and 20 ft wide, the backwash rate is 15 GPM/ft2,for 10 minutes. What is the backwash volume in gallons?
SECOND. By using the KEY WORDS you see this is a (Filtration) problem, that includes (backwash volume, gallons).
The Formula (F) and Conversions & Calculations (C&C) shown below.
Area, Ft2 = Length x Width (C&C)1
Backwash vol (Gal) = Filter,ft2 x Backwash, GPM/ft2 x Time/min (F)2
THIRD. Follow the solution procedure above to solve the problem!
65 ft x 20 ft = 1,300 ft2
1,300 ft2 x 15 GPM/ft2 x 10 min = 195,000 gallons
Backwash Rate - 1
FIRST. Read the question CAREFULLY and look for KEY WORDS to help you decide what formula to use.
If the backwash volume is 300,000 gallons and the filter area is 600 ft2, and the backwash has been flowing for 15 min, what is the back wash rate in gallons per minute/ft2
SECOND. By using the KEY WORDS you see this is a (Filtration) problem, that includes (backwash rate, gpm/ft2).
The Formula (F) and Conversions & Calculations (C&C) shown below.
Backwash Rate GPM/ft2 = Backwash Volume Gallons (F)
Filter Area, ft/2 x Time,min
THIRD. Follow the solution procedure above to solve the problem!
120,000 gal = 120,000 gal = 13.33 gpm/ft2
600 ft2 x 15 min 9,000 ft2/min