Page 438 - Civil Engineering Formulas

364 CHAPTER THIRTEEN

Air vent
Combined Storm
sewer sewer Sewer
Siphon
Bypass
Weir

(a) (b)

Wet-weather
flow

Combined
Sanitary Storm
sewer
sewer sewer
(c)

FIGURE 13.2 Flow-regulating devices for sewers: (a) Side weir. (b) Siphon spillway.
(c) Leaping weir. (Merritt—Standard Handbook for Civil Engineering, McGraw-Hill.)

where l length of weir, ft
h depth of flow over weir at down-stream end, ft

Siphon spillways are better adapted to handling large storm water and sewer
flows. The area for the siphon throat, A sq ft, is:
Q
A (13.10)
c 2gh
3
where Q discharge, ft /s
c coefficient of discharge, which varies from 0.6 to 0.8
g acceleration due to gravity 32.2 ft/s 2
h head, ft

DESIGN OF A COMPLETE-MIX
ACTIVATED SLUDGE REACTOR

The volume of the reactor can be determined using the following equation
derived from Monod kinetics:

c QY(S o S)
V r (13.11)
X a (1 k d c )