Environmental Engineering Reference
In-Depth Information
B.
Basic water
C.
Toxic pollution
D.
Thermal pollution
E.
Nutrient pollution
82.
During which step in the sewage treatment process is oxygen added to start aerobic decomposition?
A.
Pretreatment
B.
Primary treatment
C.
Secondary treatment
D.
Tertiary treatment
E.
Final treatment
Questions 83-84 refer to the following dose-response curve.
83.
Which point represents the LD
50
?
A.
A
B.
B
C.
C
D.
D
E.
E
84.
Which point represents the threshold?
A.
A
B.
B
C.
C
D.
D
E.
E
