Post on 19-Jun-2020
0
50
100
150
200
250
0 0.5 1 1.5 2
Retention time, tR (days)
Su
bstr
ate
, S
; B
iom
ass, X
(m
g/L
)
0
25
50
75
100
125
Tre
atm
en
t eff
icie
ncy (
perc
en
t)
S (mg COD/L)
X (mg VSS/L)
Efficiency (percent)
Lecture 17.xls 2/20/2006
StirredUnstirred
00 2
Solids Retention Time (days)
EFFECT OF SOLIDS RETENTION TIME, θc, ON THE SETTLING PROPERTIES OF ACTIVATED SLUDGE
4 6 8 10
2000 mg/L-MLSS
12 14
Zone
Set
tling
Vel
ocity
, ft/h
r
4
8
12
16
20
Figure by MIT OCW.
Adapted from: WEF. Wastewater Treatment Plant Design. Alexandria, Virginia: Water Environment Federation, 2003.
0
1000
Aer
atio
n Ta
nkM
LSS
Con
cent
ratio
n, m
g/L
2000
3000
4000
5000
6000
1Return Sludge Ratio, R:Q
TYPICAL OPERATING RANGE FOR ACTIVATED-SLUDGE SYSTEMS
Common operating range
Suggested maximum
2 3
SVI = 50 SVI = 100SVI = 150SVI = 200SVI = 400
Figure by MIT OCW.
Adapted from: WEF. Wastewater Treatment Plant Design. Alexandria, Virginia: Water Environment Federation, 2003.