TM 5-852-5/AFR 88-19, Volume 5
CHAPTER 9
WASTEWATER TREATMENT
9-1. General.
rates ranging from 60 to 80 gallons per capita per
day.
Basic design criteria for domestic wastewater
c. Temperature. The wastewater temperature at
treatment systems can be found in TM 5-814-
many cold region facilities tends to be at least 50
3/AFM 88-11, Volume 3. This chapter provides
degrees F due to transmission in insulated and
information and guidance on those aspects unique to
sometimes heated lines. The heat available in this
cold regions and presents general design criteria for
incoming wastewater should be considered during
those treatment systems most commonly used in the
process design.
Arctic and Subarctic.
d. Flow variations. The diurnal flow pattern at
military installations tends to be the same regardless
9-2. Wastewater characteristics.
of climate and TM 5-814-3/AFM 88-11, Vol.3 must
Wastewater characteristics in the cold regions will
be used to determine peak and minimum flow ratios
generally be different from those in temperate
for design purposes.
regions, with respect to quantity, quality, and
temperature. The total quantity of wastewater dis-
9-3. Unit operations.
charged at military installations in cold regions tends
Practically all of the basic unit operations used in
to be very close to the quantity supplied for potable
waste water treatment are affected by temperature
water use since there is little external or industrial
through liquid viscosity changes or changes in
use, storm water is usually excluded, and
chemical reaction rates. An analysis during the early
groundwater infiltration is not a factor in the newer
stages of design is required to predict the thermal
insulated and tightly sealed pipe systems. As a result
status of major components in the treatment system.
wastewater in the Arctic and Subarctic tends to be
If wastewater temperatures above 50 degrees F are
more domestic in nature and higher in strength than
expected and the entire system is to be housed in a
at comparable facilities elsewhere.
heated building, then conventional practice as
a. Quantity. The determination of design flows
defined in the TM 5-814-3/AFM 88-11, Vol. 3 will
should be based on a special analysis of the installa-
be used. If temperatures below 50 degrees F are
tion. The population equivalents and capacity fac-
expected, or significant temperature changes are
tors presented in TM 5-814-3/AFM 88-11, Vol.3
allowed to occur within the system, then
will tend to overestimate the volume of flow to be
adjustments will be necessary in the design of the
expected at remote installations in the Arctic and
unit operations. Figure 9-1 will be used to make the
Subarctic with small populations. This may result in
necessary adjustments in design to compensate for
operational problems with some biological treatment
viscosity effects. The power requirements for
units. Selection of less sensitive processes or use of
mixing, the detention time or size of grit chambers
two smaller units in parallel will avoid the problem
and primary clarifiers and the efficiency of gravity
if the design cannot be based on actual flows.
filters will all be adjusted using figure 9-1 where low
b. Quality. The mass of pollutants in cold region
temperature liquid is expected. For example, a
wastewaters is comparable to that in other locations
detention time of 2 hours is typiclly specified for
but the concentration will generally be higher
primary clarifiers. If wastewater at 35 degrees F is
because of lower water usage rates. For example,
expected, then the detention time will be increased
TM 5-814-3/AFM 88-11, Vol.3 allows a
as follows:
biochemical oxygen demand (DOD) loading of 0.2
pound per captia per day. At flow rates of 100
(3.07) e-0.0165T (from figure 9-1)
Multiplier =
gallons per capita per day, that results in a BOD
At 35EF =
(3.07) e-0.0165(35)
concentration of about 240 milligrams per liter
Adjusted time =
(2 hr)(1.723)
(mg/L). At remote installations in the cold regions
=
3.45 hr.
the DOD concentration will normally be over 300
mg/L for domestic wastewater, at the typical flow
9-1
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