Factor

Name

Low actual

High actual

Low coded

High coded

A

Contact time

0.5 h

6 h

−1

1

B

Phosphate concentrations

50 ml∙gm

250 ml∙gm

−1

1

C

Dosage

0.05 gm

0.1 gm

−1

1

D

pH

2

7

−1

1