4. The quantity of chlorine in ppm required to satisfactorily chlorinate sewage is usually
A. 95-120
B. 0-25
C. 125-150
D. 60-90
4. The quantity of chlorine in ppm required to satisfactorily chlorinate sewage is usually
A. 95-120
B. 0-25
C. 125-150
D. 60-90