Device, classification and types of septic tanks. Equipment selection criteria and popular models. The septic tank is the main element of the country sewage system, which is used to collect contaminated domestic wastewater, separate it by fraction for subsequent filtration and safe disposal. Our article is about the types of tanks for a private house.
Features of the septic tank device
The septic tank works on the principle of natural settling using soil and biological treatment of wastewater. It is a container of 2-3 compartments, branch pipes for supplying water contaminated with waste and its removal after processing.
Sewage drains pass sequentially through hydraulic locks into each compartment, starting from the first. Primary waste treatment takes place in it. At the same time, their insoluble fractions in the form of sand, vegetable peelings and other things naturally settle to the bottom of the chamber.
In the second section of the septic tank, organic matter is decomposed. In it, biological treatment facilities process waste into sludge.
The third section brings the degree of liquid purification up to 65%, using gravitational sedimentation of fine suspensions in water.
After cleaning in a septic tank, the process is completed by soil filtration, for which a system of drainage pipes is used.
Types of septic tanks according to the principle of action
All septic tanks are divided into groups according to the principle of action, material and methods of location. In turn, each of these groups is represented by reservoirs of several types. According to the principle of action, they are accumulative, deep cleaning and filtering. Consider each of these types of septic tanks for the home.
Accumulative septic tank
It is a modern cesspool. Such a septic tank has no compartments. Sewage is removed from it by pumping out and removing it by a sewage truck equipped with a tank.
The basis for the installation of a storage septic tank can be an insignificant daily volume of waste, the proximity of a natural reservoir, well or well, lack of space for the location of a full-fledged treatment facility, lack of electricity on the site.
The body of the tank is usually made of PVC, reinforced concrete or steel. The latter option is rarely used due to the poor resistance of the metal to corrosion.
The installation of a reinforced concrete well is a rather laborious process, which also requires the use of lifting equipment. The advantage of such a structure can be called resistance to seasonal soil deformations.
Plastic tanks are hermetically sealed and have a high chemical resistance to the environment of sewage. Such septic tanks serve for about 50 years. Their squeezing is prevented by special stiffening ribs provided by the design of the apparatus. To fix the septic tank with anchors and keep it from floating up, a concrete base is used. Its slab can be made locally or purchased. A level sensor that can be fitted to the reservoir will prevent it from overfilling.
Filtering septic tank
Some types of septic tanks and types of soil on which construction is planned are technologically incompatible. This applies to filter tanks. Such a septic tank has no bottom. It is installed if the soil has good drainage characteristics. In this case, all sanitary standards must be met.
When installing a container without a bottom, the following conditions must be met:
- The depth of the pit for the septic tank is at least 2.5 m.
- The drain hole must be located at a height of at least 0.8 m from the bottom of the tank.
- To avoid weakening the base under the house, the distance from the structure to a one-story building should be more than 3 m, to a two-story one - 5 m.
- The volume of the septic tank is recommended to be calculated based on the average daily water consumption.
For the manufacture of a filtering septic tank, tires, concrete rings and bricks are used. Monolithic concrete tanks can be rectangular.
Filtering septic tanks can have from 1 to 3 chambers. The first of these is a sump. From it, through the overflow pipe, the light fractions of waste penetrate into the 2nd section, where they are processed without air access by anaerobic bacteria. Through the drainage layer of the bottom, the purified liquid enters the ground. If there is a significant amount of wastewater, the tank without a bottom is equipped with an additional chamber.
The main advantages of filter septic tanks include the following:
- The ability to install in the absence of technology and use for the construction of scrap materials;
- Low cost of work;
- Ease of maintenance and reduction of its cost due to the rare use of sewage services.
The disadvantages of such septic tanks include the lack of the possibility of their installation with a high level of groundwater.
Deep cleaning septic tank
Such a tank belongs to the type of septic tanks that allow you to achieve maximum cleaning. Treated water is used on the farm and for irrigation of plants.
The facility implements 3 cleaning methods:
- Mechanical … Provides for sedimentation of effluents with their separation into fractions and precipitation of heavy particles.
- Biological … Uses purification with aerobic bacteria.
- Chemical … Within the framework of this method, disinfectants are used.
The first chamber of the septic tank serves as a settling tank in which liquid waste is accumulated and divided into fractions. The second chamber is equipped with a connected aerator, which saturates it with oxygen necessary for the vital activity of aerobic microorganisms that process wastewater. Disinfection of liquid with chemicals is performed in the third chamber of the septic tank.
The advantages of such a system are the following:
- The increased degree of wastewater treatment allows them to be discharged into a reservoir or into open ground;
- There is no smell inherent in sewage;
- Simple installation;
- Autonomy, which does not require the intervention of the owner of the site in the work of the sewage system.
The disadvantages of the system include its high cost and dependence on electricity.
Types of septic tanks by material
All types of septic tanks for summer cottages differ in the material from which they are made. It can be plastic, brick, scrap materials, concrete and metal.
Plastic septic tank
An important advantage of a plastic tank is its resistance to many types of corrosion arising from the effects of chemically aggressive sewage drains. In addition, such a septic tank is absolutely sealed, has a low weight, which makes it possible to reduce the labor intensity of its installation. Tightness makes it possible to install it without burying it into the ground. If the plastic product is planned to be located in the pit, it is attached to a concrete slab poured into the bottom of the recess.
Ready-made factory septic tanks with a plastic body work according to the following scheme:
- In the first compartment, fermentation takes place with the division of effluents into components. Solid inorganic compounds fall to the bottom of the container.
- Conditionally purified water through the overflow pipe enters the 2nd chamber, where organic matter is processed.
- The final purification of 75% takes place in a floating biofilter.
For additional treatment of effluents, an infiltrator is used, which has a crushed stone layer. Passing through it, completely purified water is absorbed by the earth.
Concrete septic tank
The most durable structures are made of monolithic reinforced concrete or concrete rings. The monolithic septic tank is completely sealed, easy to maintain, its operating time is longer than that of plastic tanks.
The design of a monolithic septic tank is associated with the tasks that he has to solve. Therefore, such a reservoir can have one or more chambers, be made with or without a bottom.
Installation of a septic tank from concrete rings is faster, but there is a need to use lifting mechanisms. Seams between products require sealing. If not done, untreated wastewater can penetrate into the ground, which is fraught with contamination.
When installing a storage septic tank from rings, a concrete slab of suitable size is pre-mounted on its bottom.
Brick septic tank
The masonry of the walls of such a structure is carried out "in brick". The outer and inner parts of the finished structure are covered with a waterproofing compound. From the inside, a brick septic tank is pre-plastered with mortar to ensure its tightness and extend its service life.
If the septic tank is filtering, a strip foundation is made for its walls, if it is accumulative, a base in the form of a slab is made.
Metal septic tank
It can be done if the farm has a suitable tank. Iron is susceptible to corrosion, so the purchase of such a container is impractical.
The cost of tanks made of corrosion-resistant stainless steel is very high. This makes the manufacture of a septic tank from such metal economically unprofitable.
With small volumes of drains, septic tanks can be made from scrap materials. These include tires, plastic barrels and other products suitable for installation.
Varieties of septic tanks by location
Any types of septic tanks for sewage can have a vertical or horizontal orientation.
Tanks are mounted vertically if the site is small and you want to save space on it. Usually these are storage tanks that require periodic cleaning. Modern deep cleaning stations are considered complex vertical septic tanks. Their advantage lies in their compactness and the absence of freezing of drains in winter.
If the site is large, it is advisable to build a horizontal septic tank. A pit for it will need less depth than in the previous case. This allows you to reduce labor and time costs for earthworks.
How to choose the right septic tank?
Many factors influence the choice of a septic tank. It would be correct to examine the soil on the site before buying a container or building. Then it will be possible to determine the depth of the pit for the tank, as well as the slope of the pipes for the rapid flow of drains into it.
If the soil in the country is sandy, you can install a filtration field and use an inexpensive anaerobic septic tank.
On clayey soil, where natural filtration is excluded, it is better to install a model with biological treatment.
With a high location of groundwater, the tightness of the septic tank is important. Here, the best option would be a plastic container. And instead of a filtration field, biological treatment is suitable.
The climate of the region also affects the choice of a septic tank. For the conditions of the North, the best option would be a concrete tank, its material perfectly tolerates temperature changes.
When buying a septic tank with a biofilter, you need to remember that long-term downtime of such a structure in the absence of residents in the house and, therefore, sewage drains negatively affect aerobic bacteria, which need a breeding ground for liquid waste. Therefore, it is recommended to use this cleaning system if there are permanent residents in the house.
The choice of the number of septic tanks is associated with the daily water consumption:
- Up to 1 m3/ day - a one-chamber suburban mini-septic tank is suitable;
- Up to 10 m3/ day - two-chamber reservoir;
- More than 10 m3/ day - three-chamber capacity.
With a large number of types of septic tanks, buying the right device is often a difficult task. We recommend purchasing products from manufacturers that are reputable and well-deserved in the market. The most popular models include septic tanks Tank, Topas, Unilos, Tver, Bars and Topol. What are the septic tanks - look at the video:
For the correct choice of treatment equipment, it is necessary to study its main types and principles of operation, take into account the operating conditions of the septic tank, the type of soil, the number of people in the house and the duration of their visits, correctly assess the budget for construction and only then make a decision.
