What is necessary prior to trickling filters?

Biological action takes place in a rapid filtration unit.

When filled which of the following material both nitrogen and BOD are removed?

What is the percentage of wash water?

The fine flocs escape and cannot b captured by tube settlers.

What does EDI stand for?

Which of these represent the settling velocity of tubesettlers?

For plastic type high filtration rate trickling filters what would be the BOD removal rate?