Environmental Engineering Reference
In-Depth Information
Example 7.8
Problem:
An RBC has a total media surface area of 102,500 ft
2
and
receives a primary effluent flow rate of 0.269 MGD. If the soluble BOD
concentration of the RBC influent is 159 mg/L, what is the organic load-
ing rate in lb/day/1000 ft
2
?
Solution:
8.34 lb
1 gal
0.269 MGD159 mg/L
×
×
=
356.7lb/da
y
356.7lb/day
102,500 ft
1000 (number)
1000
3.48 lb/day/1000ft
2
2
×
=
(unit)
7.4.7.4 RBC Hydraulic Loading Rate
The manufacturer normally specifies the RBC media surface area,
and the hydraulic loading rate is based on the media surface area, usu-
ally in square feet. Hydraulic loading on RBCs can range from 1 to 3
gpd/ft
2
.
Example 7.9
Problem:
An RBC treats a primary effluent flow rate of 0.233 MGD.
What is the hydraulic loading rate in gpd/ft
2
if the media surface area
is 96,600 ft
2
?
Solution:
233,000 gpd
96,600 ft
2
=
2.41 gpd/ft
2
7.5 ChaPTer revieW QuesTions
7.1
What type of waste treatment pound is most common?
7.2
Give three classifications of ponds based on their location in the
system.
7.3
Describe the processes occurring in a raw sewage stabilization
pond (facultative).
7.4
How do changes in season affect the quality of the discharge from
a stabilization pond?
7.5
A wastewater treatment pond has an average length of 690 ft with
an average width of 425 ft. If the flow rate to the pond is 300,000
gpd and it is operated at a depth of 6 ft, what is the hydraulic
detention time in days?
7.6
A pond 730 ft long and 410 ft wide receives an influent flow rate
of 0.66 ac-ft/day. What is the hydraulic loading rate on the pond
in inches per day?
