septic tank

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septic tank,

underground sedimentation tank in which sewage is retained for a short period while it is decomposed and purified by bacterial action. The organic matter in the sewage settles to the bottom of the tank, a film forms excluding atmospheric oxygen, and anaerobic bacteria attack the solid matter, causing it to disintegrate, liquefy, and give off gases. The gases are discharged from a vent and the liquids overflow through an outlet into a disposal field where they can leach into the soil. Here aerobic bacteria purify the liquid. The Imhoff septic tank, an improvement over the ordinary septic tank, is still used in the United States; it is a two-story structure with the upper compartment used for settling the sewage, the lower one for the anaerobic disintegration of sludge. A sloping floor enables solid material to slide to the lower compartment, where, since the sludge is separated from the material in the sedimentation compartment, the action is more rapid. A cesspool is a simpler underground structure that allows the liquids to leach directly into the soil while retaining the solids. The solids are not as efficiently decomposed as in a septic tank and more frequent cleaning is necessary. Also, as the effluent is likely to contain more coliform bacteria than that of a septic tank, cesspools pose a greater threat to water supplies. Septic tanks and cesspools are usually used in rural areas. For urban sewage-disposal systems, see seweragesewerage,
system for the removal and disposal of chiefly liquid wastes and of rainwater, which are collectively called sewage. The average person in the industrialized world produces between 60 and 140 gallons of sewage per day.
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Septic tank

A concrete or steel tank where sewage is partially reduced by bacterial action. The liquids from the tank flow into the ground through a tile bed.

Septic Tank

 

a tank for the treatment of small amounts (up to 25 cu m daily, less frequently, up to 50 cu m) of household sewage. A septic tank is an underground horizontal settling reservoir with one to three compartments, through which the sewage flows in sequential order. After preliminary treatment (clarification) in the septic tank, the sewage is subjected to biological purification in beds of underground filtration or in sand-gravel filters. Up to 90 percent of the suspended material is retained in a septic tank.

septic tank

[′sep·tik ‚taŋk]
(civil engineering)
A settling tank in which settled sludge is in immediate contact with sewage flowing through the tank while solids are decomposed by anaerobic bacterial action.

Septic tank

A single-story, watertight, on-site treatment system for domestic sewage, consisting of one or more compartments, in which the sanitary flow is detained to permit concurrent sedimentation and sludge digestion. The septic tank is constructed of materials not subject to decay, corrosion, or decomposition, such as precast concrete, reinforced concrete, concrete block, or reinforced resin and fiberglass. The tank must be structurally capable of supporting imposed soil and liquid loads. Septic tanks are used primarily for individual residences, isolated institutions, and commercial complexes such as schools, prisons, malls, fairgrounds, summer theaters, parks, or recreational facilities. Septic tanks have limited use in urban areas where sewers and municipal treatment plants exist. See Concrete, Reinforced concrete, Structural materials

Septic tanks do not treat sewage; they merely remove some solids and condition the sanitary flow so that it can be safely disposed of to a subsurface facility such as a tile field, leaching pools, or buried sand filter. The organic solids retained in the tank undergo a process of liquefaction and anaerobic decomposition by bacterial organisms. The clarified septic tank effluent is highly odorous, contains finely divided solids, and may contain enteric pathogenic organisms. The small amounts of gases produced by the anaerobic bacterial action are usually vented and dispersed to the atmosphere without noticeable odor or ill effects. See Sewage, Sewage treatment

septic tank

household septic tank, cross section
A watertight, covered receptacle designed and constructed to receive the discharge of sewage from a building sewer, separate solids from the liquid, digest organic matter and store digested solids through a period of detention, and allow the clarified liquids to discharge for final disposal.
References in periodicals archive ?
A septic system that was properly designed and installed needs only occasional "pumping" to remove the sludge and scum from the tank.
Septic systems generally have a lifespan of about 25 years in any case, officials say.
While it acknowledged an ambiguity in the statute, the Court ultimately sided with the State, and declared that defendants who are guilty of unlawful operation of a solid waste facility or septic system can be subject to both civil fines and criminal penalties.
1 rule in septic system maintenance is to routinely have your tank pumped by a licensed expert.
The Department of Environmental Services says about 85 percent of all houses in New Hampshire are on septic systems rather than being connected to urban wastewater treatment systems.
Extremely light, the system can be easily carried and installed by one person in a septic system for commercial and residential building sites.
The following discussion proposes definitions for the terms "septic-system malfunction rate" and "percentage of septic systems in malfunctioning status.
For those facilities on septic systems, know that ethylene glycol is a DEADLY POISON, not just if you ingest it directly, but to your septic systems as well.
Enteropathogens can also be released unintentionally on top of the land surface when a septic system malfunctions because of age or neglect.
We investigated losses of nitrate for a domestic septic system in the watershed of Quashnet River, Cape Cod.
The project is necessary to combat extensive septic system problems that have resulted in public health concerns, affected property values, and expensive repairs to comply with current Massachusetts Title V septic system requirements.