MIL-HDBK-1165
Section 6:
WATER CONSERVATION OPTIONS:
DISPOSAL
6.1
Sewage Treatment. After your water supply has been
distributed and used, it either returns directly to the
groundwater, if used for irrigation purposes, or it is collected
at a sewage treatment plant. Even at your sewage treatment
plant, conservation options are available. Sewage treatment
plants do not operate at peak flow 24 hours a day, and in some
instances will find periods of operation at less than half of
their design flow rate. If the flow into the grit chamber falls
below the specified minimum, make-up water must be added in order
to keep the plant operating efficiently and effectively. Instead
of using potable water for this make-up, a simple effluent return
line from the effluent discharge point back to the head end of
the plant can be installed.
As with any conservation measure though, an analysis to
determine the costs and benefits of such a set up should be
performed. If your plant only uses make-up water occasionally,
or if the head end is quite a distance from the discharge, then
this type of return system may not prove to be economical.
6.2
Water Recycling, Reclamation, and Reuse. In addition
to installing the water-conserving devices discussed throughout
Section 5, it is also possible for you to conserve water at your
base by reusing the water. Common uses of reused water include:
irrigation; toilet and urinal flush water; and cooling tower
make-up water. EPA/625/R-92/004 Manual, "Guidelines for Water
Reuse," contains in-depth discussions on reuse and reclamation
systems as well as a state-by-state listing of state regulations
and guidelines for these systems.
6.2.1
Types of Wastewater. There are two types of wastewater
generated from offices and residential facilities; (1) graywater
and (2) blackwater. Graywater is water discharged from bathroom
sinks, showers, and washing machines. It generally contains dirt
and soap or detergents. Blackwater refers to water used to flush
waste from toilets, urinals, dishwashers, and kitchen sinks. It
contains food or human waste.
Both graywater and blackwater require some level of
treatment before they can be put to beneficial use. Graywater is
generally filtered and, if needed, treated biologically or
chemically to remove any dangerous, disease-causing
microorganisms. It may also require treatment to reduce the
levels of cleaners present. Graywater is most commonly used in
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