Septic tank device: principle of operation and basic organization schemes

How to choose a convenient location for the structure on the site

The organization of a local treatment plant requires the implementation of several basic rules. The weakening of the soil under the foundation of a residential building or in the area of ​​\u200b\u200bits location can lead to collapse. It is not recommended to have a septic tank in this area.

The layout of the septic tank on the site

Summer cottages can be located on a slope. In such conditions, it is necessary to organize a septic tank below the level of the house. There are also restrictions on the construction of a treatment facility in the vicinity of a well or well.Sources from which water is abstracted can become contaminated with water contaminated with harmful bacteria.

It is better to abandon the construction of a septic tank with your own hands for a private house with a high level of groundwater. The design will not only be inefficient, but may also cause a fine from the sanitary and epidemiological supervision.

An expedient solution to this problem may be the construction by specialists of a two-section tank with a sufficient level of sealing, where there will be no filtering bottom and high-quality waterproofing will be performed.

Recommendations for placing a septic tank for a private house

Calculation of depth and volume for the construction of a structure

The digging of septic tanks in summer cottages is carried out on the basis of the location of the groundwater level

The average depth of soil freezing is also taken into account.

In order for the cleaning process to maintain its stability under the influence of various weather conditions, it is necessary to achieve a positive temperature. High groundwater prevents the structure from being buried below the freezing level of the soil. In such cases, warming is done.

Recommendations for the location of the septic tank depending on the depth

The following materials can be used for the insulation procedure:

• expanded clay;
• foam crumb;
• sheet expanded polystyrene;
• other materials of the modern generation, having the appropriate properties.

Filtering and storage chambers must have a certain volume. This indicator is calculated taking into account the volume of daily drains.

Scheme of installation of a septic tank for a country house

The following points are taken into account:

• features of household appliances that are present in the house;
• mode of operation of the site and the residential building on it;
• the number of tenants permanently residing in the house;
• plumbing fixture system.

If the house is well equipped and operated throughout the year, each tenant needs about 200 liters of water. The septic tank copes with such a volume of drains in three days, and the calculation of the volume is carried out according to the formula:

Y x 200 l x 3 days = V, where

Y is the number of residents, V is the volume of containers.

Recommended distance to the septic tank from the wall of the cottage

The principle of operation and the device of a septic tank in a private house on the example of the main models

The cesspool, which was traditionally settled on the territory, is a thing of the past. To avoid soil contamination, discharge into it should not exceed 1 m³ / day in volume. But this is unrealistic, since in a modern private house, by definition, there is a bathroom and a toilet room, and in addition, some household appliances that use water (for example, washing machines and dishwashers).

Therefore, a septic tank, no matter what design it is, is the only acceptable solution when organizing a sewer system. To choose the best option for this device from a large number of different models, you need to know how a septic tank works, its device and principles of operation. This is what we'll deal with.

Types of septic tanks

By execution

Quite often, septic tanks are mounted independently, assembled from separate structural elements (for example, from concrete rings). As a rule, with one compartment, which simultaneously functions as a sump and filter. This option does not provide the proper degree of purification, therefore it is only suitable for a summer cottage, but not for a full-fledged residential building.Installation of a more complex structure, especially on its own, requires not only skillful hands, but also a certain engineering training.

All industrial septic tanks - designs are mainly multi-chamber, for 2 or 3 compartments. In fact, these are mini-cleaning stations for universal use. The number of chambers determines the degree of wastewater treatment, and only (except for the cost of the sample).

By connection

• With electricity consumption.
• Non-volatile. The most convenient option, especially for country houses that are not provided with a reliable alternative source of electricity.

By type of purification

• Soil.
• Biological.

Structural elements of a septic tank

Sump - 1st chamber. Drainage from the sewer pipe enters it. Its purpose is to separate solid suspensions from liquids (preliminary, coarse cleaning). Heavy fractions gradually settle to the bottom (the process takes several days), and the liquid gradually flows into the next compartment.

Filter - 2 and 3 cameras. They carry out post-treatment of waste water. Here the process is somewhat different - biological. It involves bacteria that finally decompose the remaining suspensions.

Drainage well (chamber). The execution of this part of the septic tank depends on the specific model. It serves to ensure the removal of clarified liquid outside the territory. As an option, to remove liquid from a 2-chamber septic tank, a filter field is arranged (if the size and layout of the territory allow). If it is impossible to equip it, an infiltrator is installed, from which purified water goes into the ground.

Additionally - a ventilation pipe (for the removal of gases formed) and a hatch through which the inside of the tank is cleaned.

Types of septic tanks

single chamber

One of the models (from reinforced concrete rings) is shown in the figure.

The plastic counterpart works on the same principle.

Double chamber

Such models are quite suitable for a small private house, if there is a tap outside the territory.

It is undesirable to organize drainage directly on the site, since the quality of cleaning is not the highest, and there is a risk of contamination of groundwater. It is especially important if water is taken from a well or well on limestone (no more than 10 m deep).

Three-chamber

Provides the highest possible cleaning of drains.

The principle of operation is easy to understand from the diagrams.

On a note! The most popular models of septic tanks in the private sector are Topas and Tank. They are characterized by a variety of assortment, reasonable prices, ease of installation and maintenance. In principle, these are the main criteria for choosing cleaning devices.

The influence of the material on the properties of the septic tank

A great influence on the functioning of a septic tank for a country house is exerted by the material from which the frame of the sewer system is made.

Among consumers, models made from modern raw materials in the form of plastic and fiberglass have become very popular.

Such samples of treatment systems have a number of undeniable advantages:

1. Plastic septic tanks are completely sealed, which absolutely eliminates the penetration of an unpleasant odor to the surface and the ingress of sewage into the ground.
2. The weight of these structures is very small, due to which their installation does not require the use of special equipment and may well be done by hand.However, this property of the septic tank can also partly act as a disadvantage, since, due to the excessive lightness of the structure, it can be easily damaged inside the soil in the event of movement of its layers or due to changes in the groundwater level.
3. Plastic and fiberglass structures are resistant to corrosion deposits, which is especially important during precipitation.

In order for the septic tank not to deform, its walls must be of sufficient thickness, and the entire structure must be further strengthened by mounting special ribs on it, which give the system rigidity. Thanks to the equipment of such a system, you can forget about the need to concret the walls of the hole for the septic tank.

Some owners choose brick as a material for a septic tank. The laying of such a system does not differ in any complexity, however, such structures have a significant drawback - these are their poor tightness indicators.

Therefore, in the case of arranging a brick septic tank, it is extremely important to lay a waterproofing layer outside and inside its walls, having previously treated them with a cement-based solution. Another material used today for the equipment of autonomous sewer systems is reinforced concrete.

The designs of septic tanks mounted with its help are of two types:

• systems on a monolithic basis (construction begins with digging a pit and arranging formwork);
• prefabricated type septic tanks, which are assembled much easier - by using ready-made rings.

Thus, it can be noted that the arrangement of a septic tank for a country house is an extremely necessary process, therefore, such work must be approached as responsibly as possible.To do this, you can study various photo and video materials that are always available from qualified specialists, so that the treatment system is able to serve efficiently and reliably for decades.

The principle of operation of autonomous sewage

The operation of any treatment plant is based on the principles of settling and sewage filtration natural or forced. For more efficient cleaning, biofilters or special enzyme preparations can be used. The mechanism of operation of septic tanks is quite complex, it consists of several stages.

1. Primary cleaning. Sewer drains through the pipeline removed from the house enter the first tank. Heavy suspensions settle to the bottom, oils and fats rise up and flow into the next compartment.
2. Waste decomposition. The sewage that sank to the bottom in the first chamber decomposes with the formation of water, carbon dioxide and a thick mass, which gradually decreases in volume and turns into silt. The cleaning efficiency in this chamber is up to 60%.
3. Secondary cleaning. In the second chamber, small particles decompose, fats and oils are diluted. To speed up this process, special preparations with bacteria and organic compounds are added to the chamber.
4. Post-cleaning. The further path of the drains depends on the type of septic tank. For post-treatment, infiltration, a drainage well, a filtration field can be used. Cleaning efficiency - 90-95%. The water is practically clean, it can be used for economic purposes, for watering fields.

Silt and mechanical impurities from the first compartment must be periodically removed. As a rule, calling a sewage truck is required no more than once a year.But still, when arranging an autonomous sewer, care should be taken to organize unimpeded access of the sewer to the septic tank.

Types of septic tanks and their device

There are several types of septic tanks, which differ in the principle of operation:

1. Biological. The liquid is cleaned from various contaminants without harm to the environment using a filter with aerobic bacteria.
2. Natural or sump without pumping.
3. Mechanical. It is divided into several settling tanks with filters for various purposes through which water is pumped.
4. Electric or compressor. Septic tank with forced cleaning. It is divided into several settling tanks, into which the liquid is pumped using a pump. This allows you to speed up the purification of water from solid fractions and sludge.

Types of septic tanks

Septic tank for a summer residence

Septic tanks are not the only way to organize sewage on your site, there are many options for its installation. So, along with factory septic tanks, affordable home-made septic tanks can also be used.

In order to design a good sewage system, it is necessary to understand the essence of the processes that occur during wastewater treatment and, of course, the availability of the necessary finances. Conventionally, septic tanks can be divided according to the following criteria:

• Mini septic.
• Local treatment facilities.

Do-it-yourself brick septic tank scheme

Deep cleaning septic tank.
Storage septic.
Non-volatile.
Single chamber.
Two-chamber.
Three-chamber.
Plastic.
Aerobic.
Anaerobic septic tank.
Vertical.
With biofilter.
From fiberglass.
From polypropylene.

There are a lot of options to choose from and buying a well-advertised cleaning device is not always the best solution; if desired, it can be built from available materials on your own. How to choose the right septic tank. read here.

Accumulation and cleaning

According to this principle, septic tanks are divided into two large groups:

• Storage tanks are the simplest variants of septic tanks, the principle of which is to accumulate wastewater and then pump it out by means of a sewage machine. These types of septic tanks are most suitable for organizing a toilet in a summer cottage.
• Treatment plants are already more complex systems, most of the stations belong to them, they purify wastewater very well and are demanding on the soil post-treatment device. Such installations cannot completely get rid of human waste products and require periodic cleaning of the residue accumulated in them.

The choice of a septic tank must be made based on the average daily volume of wastewater. If it is small, for example, in the country, where you rarely visit, you can install simple storage tanks. And in the case of permanent residence in a country house or there is no city sewerage connected to your site, then you should think about purchasing a treatment plant or make it yourself.

Anaerobic and aerobic treatment

Depending on which wastewater treatment technology is used, 3 groups can be distinguished:

• Settling tanks with soil filtration and anaerobic treatment.Most often, an anaerobic septic tank consists of a complex of tanks or one, but delimited into sections - sedimentation and clarification of effluents take place in them, and large fractions decompose without oxygen supply. Thus, the degree of purification reaches approximately 50% of the original, followed by soil filtration. It is produced mechanically - when water passes through the layers of soil, and the particles that linger on the filter are split anaerobically. This type of septic tank is autonomous and does not need to be connected to the electrical network.
• Deep cleaning stations mean devices in which purification is carried out with the help of aerobic microbes, and the conditions for their active life will be the presence of atmospheric oxygen. Compressors are used for this. In such treatment devices, the degree of purification by runoff can reach 90% and even more, with proper operation. However, their volatility can be considered a disadvantage - there is no light - there is no work.
• Complex installations are quite complex devices, but they can provide the quality of cleaning at the appropriate level; their use as a septic tank for a toilet will have a good effect on the environment. The principle of operation combines the settling and application of anaerobic and aerobic decomposition of wastewater, as well as soil water filtration.

Septic tanks can be made of metal, reinforced concrete, plastic, etc. and, depending on their dimension, be both vertical and horizontally directed. Vertical septic tanks usually represent deep wastewater treatment plants

When using septic tanks, it is important that they provide maximum cleaning and maintain their tightness throughout their service life.

Device and principle of operation

This self-contained treatment plant is internally divided into four compartments, each with its own cleaning phase. Effluent consistently passes through all four stages of purification, at the exit, according to the manufacturer, the degree of purification is 98%. Waste processing occurs with the help of aerobic bacteria that live in the presence of oxygen. To ensure their vital activity in each compartment there are aerators pumping air.

Topas septic tank device

The Topas septic tank works according to the following principle:

• Drains enter the receiving chamber, where their processing by bacteria begins. While filling is in progress, air is supplied to the chamber to activate the activity of bacteria. In the process, insoluble particles settle to the bottom, fat-containing particles rise to the surface. This compartment contains a large fraction filter - this is a large-diameter pipe in which holes are made. A pump is installed inside this pipe, which pumps the water that has passed through the filter. Thus, the drain enters the next compartment without large contaminants - they remain in the receiver and continue to be processed by bacteria. At this stage, the effluents are cleaned by about 45-50%.
• From the receiving chamber, partially purified water is pumped into the second compartment - the aerotank. When filling, aeration is switched here, which allows particles of pollution to rise above the surface of the water. Since the shape of the chamber is pyramidal, they settle quickly. About 20-30% of contaminants remain in this compartment.With the help of pumps and special airlifts, semi-cleaned effluents enter the third chamber, and excess sludge from the bottom is pumped into the stabilizer chamber.
• The third and fourth chambers are similar in structure to the second. Here, according to the same principle, the final purification of wastewater occurs.
• Clarified water from the last compartment, by gravity or with the help of pumps, is sent to the ground, to a tank where water is stored for technical use, to a filtration column, etc.

As you understand, all the work of the Topas septic tank is based on the vital activity of bacteria. They require certain conditions - the presence of oxygen, a positive temperature

Bacteria are supplied with oxygen by aerators, therefore it is very important to provide the installation with a continuous power supply. After the power is turned off, the bacteria can live for 4-8 hours. If the air supply is not restored during this time, it will be necessary to populate the installation with new

If during this time the air supply is not resumed, it will be necessary to populate the installation with new ones.

General principle of operation of the treatment plant

The functioning of any septic tank is based on the principles of gravitational settling and biological filtration by natural or forced methods. It is possible to use bioenzymatic preparations and biofilters. Conventionally, the sewage treatment sequence can be divided into several standard stages.

Stage 1. Primary cleaning. Through the sewer pipe from the house, wastewater enters the first tank or compartment. Here there is a rough cleaning of suspended large particles. Heavy suspensions (grains of sand and similar insoluble sewage inclusions) settle to the bottom of the chamber. Light fractions (fats and oils) rise to the surface and flow into the next compartment.

Stage 2. Decomposition of heavy particles.The waste that has sunk to the bottom of the first chamber begins to ferment and decompose - the duration of the process is about 3 days. As a result, sewage breaks down into a thick mass, carbon dioxide and water.

Silt accumulates at the bottom of the first compartment, which must be periodically removed. The efficiency of liquid purification in the first chamber is about 60%. This is not enough to drain into the ground, therefore additional cleaning is required (+)

Stage 3. Re-cleaning. In the second chamber, the sewage is re-decomposed. In some septic tanks at this stage, chemical (personal hygiene waste) and organic compounds break down due to the action of special bacteria and preparations.

Stage 4. Liquid withdrawal. The further path of water depends on the type of treatment system. The purified liquid can enter the tank for subsequent watering of the garden.

If the degree of purification is insufficient, then the water will go through the post-treatment process through the infiltrate, drainage well, soil filtration fields, etc.

Image gallery

Photo from

Septic tank with filter well

Filtration field in a suburban area

Improved version of the filter field

Drainage pipes in the filter trench

A schematic description of the traditional principle of operation of a septic tank conveys the general features of the process. Each modification of the treatment plant has structural and operational nuances of execution.

What to do before choosing a septic tank

We have repeatedly seen that in any sewerage system, there is nothing incomprehensible.All installation failures are caused by an adventurous approach: Oh, and so it will do! And then the drains, for some reason, don’t “go down” anywhere, stand in plumbing fixtures, stand in risers, and there are tears in the owner’s eyes and a dumb question: Why is that?

Hurry and maybe, not for engineering networks, no matter how simple they look. It is necessary to establish as a rule, the scheme of engineering networks, should be the most time-consuming stage of construction. It is possible to correct and develop it in a calm atmosphere, with a cup of coffee, and not later dig trenches with sewer pipes in the pouring rain when water flows through the toilet into the house. If you have a dacha, then about

Material for a septic tank

All modern septic tanks are made of polymers or metals.

Of the features of polymer products, it is worth highlighting:

• polyethylene septic tanks have the lowest cost and excellent tightness. Their main disadvantage is their reduced resistance to hot water.
• polypropylene septic tanks are more durable and more resistant to aggressive environments and temperature fluctuations.
• fiberglass septic tanks are the best option from polymers, despite the higher cost. They have increased resistance to aggressive environments (including chemically active substances). They can be used for processing industrial wastewater.

Metal septic tanks have the following features:

• susceptibility to temperature fluctuations. When operating the product in the cold season, it is necessary to insulate it with high quality.
• metal for the device must undergo high-quality processing with waterproofing substances.

The device and principle of operation of the treatment plant

Consider how a two-chamber septic tank works without pumping out, find out the principle of water purification in this structure and figure out how to build this structure with your own hands. According to the method of water treatment, they can be divided into models:

• With soil post-treatment, in this case, filtration fields are built;
• With deep biofiltration.

The device of a septic tank with soil after-treatment

Consider what is the device of the overflow septic tank, from which water is discharged to the filtration fields. The fact on which the principle of operation of these treatment plants is based is that the effluent is approximately 99% water. The task of the treatment plant is to separate water from harmful impurities and to dispose of them.

As a rule, a two-chamber septic tank is built, which during operation provides two-stage cleaning. The scheme includes:

• A tank divided into several chambers, or separate chambers connected by overflow pipes. A two-chamber septic tank has two compartments.
• Filtration fields or filter well, i.e. installations for soil filtration of treated water.

Let's consider how such a two-chamber septic tank functions without pumping out, the principle of operation of the installation is based on the use of mechanical sedimentation processes and biological treatment:

Effluent from the house through the external sewerage pipeline enters the sump chamber.

• Accordingly, during the settling process, pre-treated water is collected in the middle of the chamber, which enters the next chamber through overflow pipes.
• The chambers are connected in such a way that the minimum amount of impurities gets to the next stage of purification. Thus, water enters the second chamber, which already contains much less various impurities.In the second chamber, water under the action of bacteria is released from the main part of organic inclusions.

The number of chambers is determined by the amount of wastewater. For small volumes (up to a cubic meter per day), single-chamber models can be used. To ensure greater productivity, two- or three-chamber are needed. But in any case, the drawing of a septic tank of this type includes filtration fields or a specially installed infiltrator or filter well. Getting to the filtration fields and passing through the ground, the effluents are freed from the remnants of impurities.

Septic tank with deep biofiltration

A slightly different septic tank technology is used when using the deep biological filtration method. Such systems are a single unit, the internal cavity of which is divided into several chambers.

They are energy dependent as they are equipped with compressors and pumps. So, the scheme of operation of a septic tank with deep biological treatment:

• At the first stage, everything happens exactly the same as in conventional septic tanks. That is, the effluent enters the sump and is divided into several fractions. After that, the water freed from large inclusions flows into the next chamber.
• The second stage of purification is based on the use of anaerobic bacteria, under the influence of which the decomposition of organic waste occurs.
• When using deep biological treatment, the septic tank scheme includes an additional chamber in which water is purified using aerobic bacteria. Air is supplied to this chamber with the help of a compressor, and the waste is quickly and efficiently split under the action of microorganisms. Therefore, it is not required to build filtering fields with your own hands.
• During their work, a small amount of solid waste is generated, which resembles silt. They will need to be periodically removed from the chambers; a built-in or fecal pump is used for pumping. Carrying out pumping is quite possible with your own hands.

Types of septic tanks and their device

Depending on the type of septic tank, its principle of operation varies. There are such types:

1. Biological. Here, a filter with aerobic bacteria is installed as a filtering mechanism. They purify the liquid from various contaminants, and do it without harm to the environment;
2. Natural or sump;
3. Mechanical. It consists of several containers into which water is gradually pumped. Each container (tank) is a kind of sump and is equipped with a filter corresponding to its purpose;
4. Electric or compressor septic tank of the forced principle of operation. As well as mechanical, it consists of several sections, but the liquid is pumped into each of them by the pump. This allows you to quickly clean the water from solid contaminants and separate the sludge.

The principle of operation of the capacitive well