Environmental Engineering Reference
In-Depth Information
final revieW exaM
12.1
What is the purpose of the sludge recirculation system?
12.2
Give three reasons for treating wastewater.
12.3
The trickling filter is 100 ft in diameter and 5.5 ft deep. The influ-
ent flow rate is 2.25 MGD, and the recirculation ratio is 0.5:1.
What is the hydraulic loading for the trickling filter in gallons per
day per square foot (gpd/ft
2
)?
12.4
Name two types of solids based on physical characteristics.
12.5
The trickling filter is 80 ft in diameter and 3.5 ft deep. The influ-
ent flow rate is 3.40 MGD, and the recirculation ratio is 0.25:1.
What is the organic loading in pounds of BOD per day per 1000
ft
3
if the primary effluent BOD is 112 mg/L?
12.6
Define
organic
and
inorganic
.
12.7
The highest organic loading in a rotating biological contactor
(RBC) train usually occurs
.
12.8
Name four types of microorganisms that may be present in
wastewater.
12.9
Microscopic examination of activated sludge is a useful tool.
What should the operator be trying to identify?
12.10 When organic matter is decomposed aerobically, what materials
are produced?
12.11 Define
flocculation.
.
12.12 Name three materials or pollutants that are not removed by the
natural purification process.
12.13 What do we call the used water and solids from a community that
flow to a treatment plant?
12.14 Where do disease-causing bacteria in wastewater come from?
12.15 What does the term
pathogenic
mean?
12.16 What is wastewater called that comes from the household?
12.17 What
is
wastewater
called
that
comes
from
industrial
complexes?
Use the following information for Questions 12.18 through 12.21:
Primary settling tank
Number = 2
Length = 190 ft
Width = 120 ft
Water depth = 12 ft
aeration tank
Number = 4
Length = 200 ft
