Post on 06-Aug-2015
Passive treatment sizingBased on loading:
Expressed in terms of gm/sq m/day
flow x chemistry
Based on detention time: Expressed in terms of volume
flow x time
Regardless of whether the system is a VFP, a bioreactor or a
limestone pond, flow is a critical factor!
RZW and Z1 Daily Discharge
0
25
50
75
100
125
150
175
200
225
Oct
-97
No
v-97
Dec
-97
Jan
-98
Feb
-98
Mar
-98
Ap
r-98
May
-98
Jun
-98
Jul-
98
Dis
char
ge
gp
m
RZW
Z1
Flow monitoring can be quite deceptive~!!!
Z1
% of days Z1
% of days RZW
% of days RZW
% of days
monthly exceeded daily
exceeded monthly exceeded daily exceeded
average 103 63% 107.6 62% 25 37% 33.6 23%
90th%tile 139 16% 146 9% 36 22% 88 10%
Some sites are simply limited in available space and the designer
simply builds as large as possible. Such a system is under
designed from the getgo.
Dr. Art Rose investigated system performancePoor performance reasons included:
Too much flow for the systemLoading too high for the system
Decreasing flow would likely have improved performance