WASTEWATER By Rick Lallish
How much influent organic matter is expected to be removed in primary treatment using a primary clarifier?
A. 10 to 20 percent
B. 20 to 35 percent
C. 35 to 50 percent
D. 60 to 75 percent
Answer: B. Primary clarifiers are designed primarily for solids removal. You can expect 60 to 75 percent removal of the influent solids content. Operators should be aware that the removal of some organic matter is a coincidental benefit. The primary clarifier also removes approximately 20 to 35 percent of the BOD. This is important to remember when factoring the BOD load on the secondary treatment
