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PRINCIPLE
OF OPERATION
TREATMENT
PRINCIPLE
The Ahead Tank™ Type
II Marine Sanitation Device is a biological aerobic (bacteria
and air) sewage treatment system. Liquid and solid wastes are
removed from the water by bacteria naturally contained in sewage.
The Ahead Tank™ consists
of three treatment stages; aeration, clarification, and disinfection.
In the aeration chamber (stage 1), the bacteria grow and multiply
using the sewage as their food supply. This action reduces the
quantity and size of the solid matter. In the clarification chamber
(stage 2), the bacterial floc is separated from the treated solid
matter. The treated water is clear and free from solids, however,
the liquid must be disinfected prior to discharge overboard to
kill any disease-causing bacteria. Disinfection is accomplished
in the clarification chamber (stage 3).
Flow
through these three stages is caused by direct displacement. When
new sewage flows into the aeration chamber, an equal volume flows
through the clarification chamber. This volume, in turn, displaces
an equal volume from the clarification chamber into the disinfection
chamber, and overboard. No internal sewage pumps are necessary.
AERATION
Sewage
is aerated as soon as it enters the treatment system, and mixes
with the aeration liquid already in the aeration chamber. Plastic
non-clog diffusers inject air near the bottom of the aeration
chamber so that the sewage remains in a state of aerobic decomposition.
This aerated liquid contains the bacterial sludge that reacts
with the sewage to start the reduction process. The movement created
by the injected air helps mix the sewage with the bacterial sludge
and prevents sludge and sewage solids from settling to the bottom.
The air discharged from the surface of the liquid in the aeration
chamber is vented to the atmosphere through a vent line connection.
CLARIFICATION
The
liquid displaced from the aeration chamber flows into the clarification
chamber for further treatment. Some of the suspended material
will settle out into the chamber below, where it will be returned
to the aeration chamber. The remaining sludge and waste material
is removed as the liquid flows upwards through the biological
filter media. Bacteria grow on the surface of the media and produce
a sticky, slimy film that traps small particles of waste. The
trapped waste is then consumed by the bacteria on the surface
of the filter media. By the time the liquid reaches the top of
the biological filter, it has passed by several layers of bacteria,
ensuring that the sludge and waste removal process is completed.
Clear water accumulates here until it is displaced into the discharge
line, and the disinfection chamber.
DISINFECTION
The
water flowing out the discharge line of the clarification chamber
is collected in the disinfection chamber (chlorine contact chamber),
where disinfecting chlorine tablets are located. In this chamber,
the water mixes with the disinfectant for a residence time sufficient
to complete the disinfection stage of the treatment process.
DISCHARGE
The
clear disinfected waste water is then discharged overboard, or
sent to a holding tank (for use in No Discharge Zones) for later
discharge. When directly discharged overboard, the disinfected
waste water flows from the disinfection chamber through a gravity
discharge connection to overboard. If desired, the treated liquid
can be retained in a holding tank, for later discharge, when the
system is used as a Type III unit.
Go to our Ahead Sanitation Systems website for more information.
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