Primary

Question 1

What does Primary treatment consist of?

Answer 1

Sedimentation & Floatation

Question 2

What velocity should the wastewater be traveling at?

Answer 2

0.03 ft/sec

Question 3

What happens when the specific velocity is reached?

Answer 3

It allows settleable solids to fall to the bottom while floatable solids to rise to the top.

Question 4

What detention time are primary clarifiers designed for?

Answer 4

1.5- 2 hours

Question 5

Main difference between primary and secondary clarifiers?

Answer 5

Primary sludge is denser than that of the secondary sludge and also the effluent is much cleaner after secondary treatment

Question 6

DO range for Effluent?

Answer 6

0-2 mg/L

Question 7

TSS range for influent? TSS range for effluent?

Answer 7

150-400 mg/L; 50-150 mg/L

Question 8

BOD range for influent? BOD range for effluent?

Answer 8

150-400 mg/L; 50-150 mg/L

Question 9

Removal efficiency for primary clarifiers?

settleable, suspended, total, bod, bacteria

Answer 9

95-99%, 40-60%, 10-15%, 20-50%, 25-75%

Question 10

Factors that affect the efficiency include?

Answer 10

Type of solids, age (in collection system), rate of flow, sludge withdrawal, suspended solids from other treatment processes