(2) Raw influent. Sometimes a treatment plant is located at such a
distance from the installation or community served that the wastewater becomes stale
and septic before arriving at the plant. Chlorine may be added to the raw influent in
order to prevent odors and to prepare the wastewater for treatment.
(3) Filter odors. Odors may be particularly objectionable from fixed-nozzle
filter sprinklers. Partial chlorination of the filter influent will reduce them.
(4) Sewer system chlorination. Production of hydrogen sulfide and other
odorous gases, septic action in the sewers, and undesirable fungus growths are
correctable by chlorination of the wastewater at a manhole or in a pumping station.
Chlorinating wastewater in Army systems, however, is normally not justified. Such
chlorination cannot replace a regular sewer inspection and cleaning program. However,
equalization is justified when contaminated storm waters or wastewaters from batch
d. Safety Precautions. Safety precautions are to be followed through the
wastewater treatment processes anytime chlorine is used. Although automatic
chlorinators provide an efficient means of adding chlorine to wastewater, they are
inherently very dangerous. They dispense chlorine gas, which is a highly poisonous
chemical. The following precautions must be taken to protect personnel working around
(1) Room separation. If chlorinators and/or cylinders are in a building used
for other purposes, a gas-tight partition separating the chlorine room from all other
portions of the building is needed. Doors to the room are to open only to the outside of
the building and are to be equipped with panic hardware. The storage area is to be
separated from the feed area.
(2) Inspection window. A clear glass, gas-tight window is to be installed in
an exterior door or interior wall of the chlorinator room to permit the chlorinator to be
viewed without entering the room.
(3) Heat. Chlorine equipment rooms are to be provided with a means of
heating for room temperature to be maintained at least 60F. This will help to prevent
the formation of chlorine hydrate in the chlorinator.
(4) Ventilation. Forced mechanical ventilation providing one complete air
change every three minutes is to be installed. The entrance to the air exhaust duct from
the room is to be near the floor and the point of discharge is to be so located as not to
contaminate the air inlet to any building or inhabited areas. Air inlets are to be so
located as to provide cross-ventilation and to prevent a fan from developing a partial
vacuum in the room. The partial vacuum would make it difficult to open the doors.
Where duct work is required to carry air to the fan, it should be laid out and spaced so
as to exhaust air from all equipment areas. Exhaust openings should be designed so
that covers are not required.