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The
plumbing that leads from all the household toilets and
sinks, connects to a main waste line which exits the
foundation and then connects to the septic tank.
The function of this pipe is to transport household
waste to the septic tank.
The
septic tank is a watertight vault in which the anaerobic
purification process begins. In the tank, density automatically
separates the sewage into three layers. The topmost layer
is called "scum". Scum is composed of materials
that float on water such as grease, oil, and fats. The
middle layer consists of liquid and suspended solids.
The bottom layer is called "sludge". The sludge
is more dense than water and is derived from much of
the solid portion of sewage waste. In the first chamber
of the septic tank a balance occurs, resulting in the
presence of anaerobic bacteria thriving in the three
above mentioned sewage layers.
Through the normal metabolic activities of these resident
bacteria, liquification of the scum and sludge layers
occur. In other words, bacteria causes organic materials,
from both the scum and the sludge layers to be broken
down into smaller sized substances. When this material
has been broken down far enough it will be taken into
the liquid layer as a suspended solid or other soluble
organic compounds. In the second chamber these solids,
of very small organic materials continue to be degraded
while in the liquid layer. Only the liquid layer in
each chamber is passed onto the next section, the scum
layer is blocked from the effluent pipe by an invert
junction. By this process the effluent in the third
chamber of the septic tank is relatively free of solids.
The third chamber is also host to a submersible pump
for the delivery of effluent to the Bio-Reactor. A return
from the Bio-Reactor to this chamber also facilitates
de-nitrification and organic phosphate removal. Finally
an emergency outflow is installed to soak away along
with a high level alarm (if fitted), in case of an electrical or
pump failure.
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Installation
The
installation of the system should be carried out by
a registered plumber, or any capable person. All electrical connections are
sub-contracted
to an electrical firm. In both cases we would use our
own staff or registered companies within the local area.
The setup and calibration of the Scarab
package
plants may only
be carried out by Scarab
trained
personnel.
Due to the complicated calculations required for the
timing, retention times and through put volumes, calibration
is carried out with the assistance of a computer
programme.
These issues are critical to the performance of our
treatment systems and require precise on site settings.
Commissioning
and handing over the plant to the customer is only done
approximately 30 days after installation. This is to
allow for the time periods that are required for the
growth of biomass, de-nitrification and phosphate removal.
A final test of the effluent carried out by eThekwini
Metro Labs in Durban and a certificate showing that
these results meet the requirements of the Water Act
completes the installation.
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