Often, owners of country houses or cottages are faced with a delicate problem — the need to dispose of wastewater generated as a result of economic activities on the site, hygiene procedures, washing dishes, and so on.
Unfortunately, inclusion in the centralized sewerage system, as well as water supply, is far from available everywhere. This is due to the fact that the infrastructure does not keep pace with the rapidly unfolding suburban construction.
The way out of this situation is to install a septic tank, a local treatment system for a small amount of domestic wastewater. A septic tank is a system in which wastewater is treated through active aeration, sedimentation and decomposition of particles, as well as filtration, including groundwater.
Device and principle of operation
How to choose a septic tank
Device and principle of operation
Septic tanks are divided into categories, depending on how wastewater is treated:
Septic tanks with dispersion (filtration) fields
Bioseptics (with biological filtration)
Septic tank with dispersion field
The septic tank is quite simple. This is an underground sump where wastewater flows through the pipeline. Now most often septic tanks are made of plastic, which ensures tightness, strength and durability. Previously, these devices were built of brick, concrete, metal and stone. Septic tanks can be of a standard shape and volume or made specifically for the needs of customers. The septic tank can be located at a distance of 5–20 m from the house. One of the advantages of a septic tank is the absence of an unpleasant odor. In addition, this device does not consume electricity.
The sediment contained in the effluents settles in the sump, and the liquid component begins to ferment under the action of anaerobic bacteria. As a result, methane is formed, which is discharged through a special pipe. At this stage, the degree of purification of the waste liquid is 50–75%. Installing a biofilter in the design allows you to increase this parameter up to 90%. In the biofilter, which most often consists of expanded clay, additional aerobic (oxygen) purification takes place.
From the sump, clarified wastewater enters the soil through the drainage network (filter field) for post-treatment. A drainage network is needed to ensure that water is evenly distributed in the soil. Drainage is a system of pipes with small holes, surrounded by rubble. It should be arranged in such a way as to avoid flooding of the foundation and basements, below the water intake and at a distance of at least 20 m from the well.
Sediment accumulating at the bottom of the sump must be periodically pumped out using a sewage truck. The regularity of this process depends on the intensity of use of the septic tank — from once a month to once a year.
In the event that the installation of a septic tank with a filtration field for some reason, for example, due to a high level of groundwater or insufficient area of the site, is impossible or difficult, a septic tank with a biological filter becomes an ideal option.
The first stages of cleaning in a bioseptic tank follow the same principle as in a septic tank with a scattering field. Further, the clarified water enters a special compartment with a biofilter.
A biofilter is a container filled with filter material, most often expanded clay. When wastewater passes through expanded clay, a film of bacteria and other microorganisms forms on its surface, decomposing organic substances that make up the wastewater. The degree of water purification in the biofilter is up to 90%.
All bioseptic compartments are located in one building. Additionally, a pump can be installed at the wastewater outlet, which pumps the treated wastewater into a ditch or other body of water.
How to choose a septic tank
In order for the treatment plant to effectively cope with its task, it is necessary to choose the right septic tank. The most important parameters that you need to pay attention to are the volume of the container and the type of soil.
Septic tank volume
The volume of the septic tank should be equal to three times the daily inflow. In other words, it is necessary to calculate how much water the inhabitants of the house spend daily, and multiply this figure by three. On average, one person consumes about 200 liters of water per day. Thus, if 4 people live in a country cottage, they spend 800 liters of water daily. This means that the volume of the septic tank must be at least 2400 liters (or 2.4 cubic meters).
When choosing a septic tank, it is very important to consider the type of soil in the area where it will be installed.
For clay soils, it is best to choose a septic tank with deep biofiltration. The fact is that the clay is practically impermeable, therefore, to ensure soil filtration in such conditions, expensive additional work must be carried out.
In areas with other types of soil (sandy, loamy), septic tanks can be used, both with soil filtration and with deep biofiltration. Please note that in sandy soils, septic tanks will most likely need to be further strengthened.
Pay attention to the level of groundwater. If it is low enough, then the sewage can be drained by gravity, and if the groundwater level is high, a forced removal system will be needed.
Installation of septic tanks must occur in accordance with the following regulatory documents:
SNiP 2.04.03–85 Sewerage. External networks and structures. This document is partially valid. According to the order of the Government of the Russian Federation of June 21, 2010 N 1047‑r, sections 2–6, 8, 9 are mandatory.
From 01/01/2013, the Code of Rules 32.13330.2012 “Sewerage. External networks and structures”, updated version of SNiP 2.04.03–85.
Installation of a septic tank
You can install a septic tank on the site yourself. To do this, it is necessary to dig a pit, lay a pipeline and perform a number of other works. However, in order for the treatment facilities to work as they should: they sufficiently clean the drains and do not annoy not only you, but also the neighbors with an unpleasant smell, you should contact a professional company whose specialists have sufficient experience in performing such work.
Please note that before the actual installation of the septic tank, it is necessary to coordinate the prepared project in the Sanitary and Epidemiological Station.
All models of septic tanks on TopClimat.ru »
The article was prepared with the help of specialists from the company “Alsel St. Petersburg.