English Instructor Manual (PDF) - Metric Version - National ...

Key Points: Discuss the relationship between filter area, fl ow rate and fi lter media rate.
Filter Area = FR ÷ FMR
FMR = FR ÷ FA
FR = FA x FMR
Activity: Have the students complete two or three problems and explain how the information can
be used by a facility operator.
Key Points: Explain that there are several different types of filtration systems used today. These
include:
High-rate sand
Diatomaceous earth (D.E.)
Cartridge
Zeolite as a media replacement for sand fi lters
Key Points: Discuss the various aspects of high-rate sand fi lters. These include:
High-rate sand fi lters can be part of a pressure system or a vacuum system
The fi ltering rate for high-rate sand fi lters is 31-50 m 3 /m 2 /hr.
Backwashing is the method used to clean high-rate sand fi lters
Explain that Zeolite is being used as a media replacement for sand fi lters
Key Points: Discuss the various aspects of diatomaceous earth (D.E.) fi lters. These include:
D.E. is a powder that, when introduced into a D.E. fi ltration system, coats screens
designed to support D.E. Multiple screens are suspended within a tank.
D.E. fi lters can be part of a pressure system or a vacuum system.
They are effective for particles larger than 1-2 microns, making it one of the most
effective fi ltration systems.
The fi ltering rate for D.E. fi lters is 81-102 lpm/m 2 .
Explain the concept of a slurry D.E. fi lter system.
Backwashing is the method used to clean D.E. fi lters. However, care needs to be taken
when disposing of old D.E. Many regulations require use of a separation tank, which
collects the D.E. for disposal.
It is recommended that a dust mask, gloves, and eye protection be used whenever
handling D.E.
Include a brief discuss of regenerative D.E. fi lters.
Briefl y discuss optional materials that can substitute for D.E.
Key Points: Discuss the various aspects of cartridge fi lters. These include:
Pleated cartridge paper provides fi ltration. This is similar to the type of paper used in
air fi lters, gas fi lters, and oil fi lters. Even many coffee makers use a low-grade cartridge
paper.
Cartridge fi lters are always pressure systems.
Cartridge fi lters cannot be cleaned by backwashing.
Final Questions: Ask the participants if they have any questions pertaining to the lesson they
have just completed. If there are participants who are still having trouble with the concepts of this
lesson, offer additional help during a break.
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