Preliminary

Question 1

What does preliminary treatment consist of?

Answer 1

Screening, grit removal, pre-aeration, and a flow meter

Question 2

What is the purpose of pre-aeration?

Answer 2

To freshen and remove oils and grease

Question 3

What is the purpose of a bar-screen?

Answer 3

Removes large solids in the influent

Question 4

What is the purpose of a bar rack?

Answer 4

It is used to screen the influent when the bar screen must be bypassed.

Question 5

How far apart is the spacing on a bar screen?

Answer 5

3/8” to 2”

Question 6

How far apart is the spacing on a rack?

Answer 6

3” to 4”

Question 7

How often should a manual screen be cleaned?

Answer 7

Enough so solids do not buildup and prevent flow into the plant

Question 8

How are screenings disposed of?

Answer 8

By burial or incineration

Question 9

What is a communitor and how does it work?

Answer 9

Device that acts both as a cutter and a screen. The solids that pass thru the screen are chopped or shredded between the two cutters

Question 10

What velocity should grit settle at in a grit channel?

Answer 10

0.7-1.4 ft/sec however 1 ft/sec is best