Septic
Tank Care
In rural areas, suburbs,
or new districts where water is available in the house, the septic
tank is an inexpensive and efficient method of disposing of sewage.
Like all systems, however, it can be abused and often neglected,
resulting in considerable trouble and inconvenience, especially
if it stops functioning in the wintertime. A system may become
inefficient because of improper location, faulty construction,
lack of attention, overloading, and other factors.
Bacterial Action
A septic tank does
not purify sewage, but only prepared it in a form ready for final
disposal in the soil. This is accomplished by bacterial action
in a single- or double- chambered tank with suitable baffles.
In this tank countless numbers of bacteria decompose the complex
sewage into more simple compounds found in solids, liquids and
gases. The accumulation of undigested solids settles to the bottom
as sludge, while a partially submerged mat of floating solids
forms at the surface of the tank as scum. Gases escape through
the house vent or are re-absorbed, and the liquid portion containing
dissolved material (with suspended particles) passes into the
soil through the absorption bed, where it undergoes final decomposition
by soil microorganisms. The necessary bacteria in the tank are
already in the sewage and do not have to be supplied. While some
of the action in the tank is brought about by aerobic bacteria,
which use up most of the available oxygen, most of the action
in the tank is anaerobic, brought about by bacteria, which can
work without any (free) oxygen.
Cleaning
All septic tanks require
cleaning at intervals. The accumulation of too much scum on the
surface and sludge on the bottom will reduce the working capacity
of the tank and consequently bacterial activity, and although
the sewage may continue to pass through the system, it will not
be properly liquefied and eventually the solids will plug the
tiles. It is advisable, therefore, to inspect the tank once a
year to determine the extent of sludge and scum accumulation.
When the combined depth of scum and sludge is about one foot,
the accumulation should be removed. Tanks under normal working
conditions should be pumped about once every three years. When
inspecting the interior of the tank, do not use matches or open
flame, as explosive gases sometimes are present. Accumulated sludge
and scum can be removed easily and effectively and disposed of
by private contractors who are licensed to perform this service.
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