What is the percentage of bacterial removal in filter beds?

Which of the following is not true in case of closing the top of the vessel?

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

What is the percentage of wash water?

For rock type low filtration rate trickling filters what would be the recycling ratio assumed?

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

What would happen if the tube settler is inclined greater than 60 degrees?

What is the angle at which a tube settler is usually inclined at?