Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
24 Cards in this Set
- Front
- Back
|
Are filters used before or after ion exchange / reverse osmosis? |
Prior |
|
|
Are filters used before or after clarification? |
After |
|
|
What are the 3 principles of filtration? |
Transport mechanism, attachment mechanism, and forces of water |
|
|
What is the supporting layers of gravel in a filter called? |
Subfill |
|
|
What are the most common filtering mediums used? |
1) sand 2) anthracite coal 3) garnet |
|
|
What is depth of a supporting bed of gravel? |
12-16 inches |
|
|
How far should sludge penetrate filter media? |
2-4 inches |
|
|
Where are most suspended solids trapped on a filter? |
At the surface |
|
|
What happens if filter media is to fine for application? |
Rapid increase in pressure drop and blinding of filter bed |
|
|
What should the backwash rate be? |
10-20 GPM /sqft |
|
|
Is backwashing effectiveness higher in warm or cold water? Why? |
Cold. More viscous = better scouring of bed to remove solids |
|
|
How many inches of sand in a typical sand filter? |
24-30" |
|
|
What micron range are most cooling tower particles ? |
0.5 - 5.0 microns |
|
|
What should flow rate through sand filter be? |
2-4 gpm/ft2 |
|
|
What media is in a dual media filter? |
20" of Anthracite coal on top of 10" of sand (sitting on gravel bed) |
|
|
What is the order of media in a multi media filter? |
Anthracite coal, sand, garnet, gravel |
|
|
Do multi-media filters have higher or lower flow rates than sand filters? |
Higher |
|
|
What is another name for DE diatomaceous earth? |
Septum filtration |
|
|
Are diatomaceous earth filters used when there is high or low suspended solids? |
Low |
|
|
Do DE filters have high or low operating costs? |
High |
|
|
How do Septum filters operate? |
A precoat is applied as the porous septum. This makes a filtering surface. Once plugged the filter needs to be backwashed which removes solids and the coating. Precoat then needs to be applied again. |
|
|
What is another option to remove solids from a septum filter? |
Air bumping |
|
|
What do septum filters excel at removing? |
Oil from condensate |
|
|
What can help improve filter runs on septum filters? |
Adding filter aid |
