The removal of sewage is one of the problems that every owner of a country house will surely encounter. Septic tanks are one of the most popular solutions to this problem - their design is adapted for cleaning and phasing out liquid sewage, leaving only solid particles for pumping. To determine which septic tank for a summer residence is better, based on the variety of soil at the installation site, the frequency of residence and the financial capabilities of the owners.
Content:
Material of storage tanks
The design of any septic tank involves the use of one or more containers located underground. They can be made independently or purchased ready-made, the main requirement is that a sufficient level of tightness is observed, and the surface is resistant to aggressive chemical elements.
Reinforced Concrete Rings
This is one of the most durable and resistant to various influences materials. After installing such a container, you can not be afraid that within a few years the structure will be washed out by groundwater and it will collapse. True, it must be borne in mind that in addition to the purchase and delivery, most likely, you will also have to pay for the installation of the rings in the pit. Also, in addition to the rings themselves, it will be necessary to purchase reinforced concrete circles for the bottom of the tank and the top into which the ventilation hatch is mounted.
Plastic storage tanks
One of the most reliable materials in terms of tightness and resistance to acids, alkalis and other aggressive components of groundwater and sewage. Of all the materials suitable for creating septic tanks, plastic is the easiest and allows for manual installation, with a minimum of assistants. With caution, it should be used only in areas with moving loose soils.
Monolithic reinforced concrete structure
It is done according to the foundation principle: it is poured directly at the installation site using removable formwork, in which the cement-sand mixture solidifies. For greater strength, reinforcement is mandatory, and for resistance to groundwater, a waterproofing layer is applied to the external walls after removing the formwork.
Metal containers
At present, metal containers for septic tanks are also being produced. The advantage of these septic tanks is their strength. The most pronounced drawback is corrosion, which in aggressive environments leads to the rapid destruction of such containers. First of all, joints are destroyed. Before use, all metal containers are treated with anti-corrosion agents, but it must be understood that all these tools will protect the container only for a while, after which active corrosion of the metal will begin.
Varieties of septic tanks and their structural differences
Each of the varieties of septic tanks represents several stages of wastewater treatment. In the initial designs, only mechanical cleaning was used, the quality of which did not exceed 70%, and with the addition of biological filters, the outlet water purity rose to 98%, which allows its use for technical purposes.
Septic tank with a filtration well
This is the easiest way to arrange wastewater treatment according to the principle of a septic tank, but in comparison with a standard cesspool, it requires certain financial investments for the purchase of ready-made storage tanks. You can also independently build them from reinforced concrete rings. In fact, the entire structure consists of several sealed containers underground, interconnected by overflow pipes. The last tank is a filtration well with a sandy bottom strewn with crushed stone.
The principle of operation of such a septic tank consists in sequentially filtering heavy elements and fats from drains. First, the entire contents of the sewage system falls into the first tank, at the bottom of which the largest and heaviest fractions settle, and water with lighter particles, when filling the first tank, flows into the second, where the process repeats. As a result, the most purified liquid enters the last well and goes into the ground through a pillow of rubble and sand.
Septic tank with a filtration field
Improved system of the previous method. The use of this technology allows to increase the efficiency of treatment facilities, as a result of which the water leaving the earth has less impact on the ecosystem, and the septic tank will be cleaned less often.
Structurally, the entire system consists of three main elements:
1 Sedimentation tank. Two or three tanks interconnected by overflow pipes, with each of them following a level below the supply.
2 Distribution well. It has a dual function: at the same time it is the next tank for settling fine particles, plus it collects water for transfer to the next cleaning stage.
3 Filtration field. It consists of a pillow of sand and gravel (gravel) with perforated pipes laid on it, which are directly connected to the distribution well. The sand and gravel pillow plays the role of the last stage of cleaning - its thickness is at least 1 meter.
The principle of operation is the sequential filtering of heavy particles. Initial rough cleaning is carried out in overflow storage tanks in which dirt is separated into particles heavier than water and fats floating on top. As a result, clarified water, in which there are light insoluble suspensions, enters the distribution well. They fall into the filtration field and are held up by a sand and gravel pad.
The whole system can be further improved by making an additional well behind the filtering field, into which water is collected that has not gone into the filtering layer. From the well, it is pumped out to a separately equipped drainage channel.
Septic tank with infiltrator
By the principle of action and efficiency, this system is equal to the filtration fields, but it wins significantly in terms of occupied space. The infiltrator itself is a long plastic container, in shape resembling an inverted trough with holes on the sides in the form of blinds. On the one hand, water is supplied to the infiltrator for cleaning, on the other hand there is a ventilation outlet. A hatch is usually arranged above, through which the infiltrator is cleaned of accumulated debris. In terms of efficiency, one tank of an infiltrator with a capacity of 400-500 liters replaces about 40 m² of filtration fields.
There are two most common designs of such a septic tank: standard and with an intermediate well. The first of them is completely non-volatile with the movement of water by gravity, consists of tanks of a sump, after which an infiltrator is mounted, which is installed on a pillow of sand and gravel.
The second scheme looks exactly the same, but between the septic tank and the infiltrator there is an additional well, inside which a drainage pump controlled by a water level sensor is installed. Water is supplied to the well through a pipe with a check valve.Due to the presence of a pump, this filtration system is volatile.
The principle of operation of the standard circuit. Sewage effluents enter the septic tank for primary cleaning of particles heavier than water. After filling the last tank, water is supplied to the infiltrator, and already after it enters the sand-crushed stone pillow for final cleaning.
The scheme with an intermediate well, in fact, works in exactly the same way, but has increased resistance to the so-called volley discharges, when for some reason a large amount of water is simultaneously discharged into the filtering unit and the infiltrator does not have time to withdraw it to the filtering sand and gravel pillow.
Septic tank with biofilter
It’s realistic to do such a filtering installation yourself, but for a number of reasons it’s better to buy a ready-made one, in which all the necessary parameters are calculated, and all the components and filtering elements are in the same housing.
Such a system has three main compartments separated from each other by walls perforated in certain places for liquid overflow:
1 Septic tank. Consists of a sump chamber.
2 Anaerobic Type Bioreactor. Depending on the model, it is a usual container - hollow or with strips of synthetic fabrics placed on the walls, not subject to decay. This creates the conditions for anaerobic bacteria.
3 Storage tank for purified water. In some cases, an additional mechanical filter is mounted here.
The principle of operation is based on the sequential flow of effluents from chamber to chamber by gravity. In the first compartment, which consists of two parts, sewage is separated into particles heavier than water, which settle on the bottom of the chamber, liquid and a film of fats that form on the surface. Secondary (coarse) cleaning of the septic tank separates particles that are not dissolved in it from the water, for which fabric or similar filters are used.
Anaerobic bacteria, which live in an oxygen-free environment, are colonized inside the second tank and, in the course of their life, decompose the remaining organic compounds in the water.
The third capacity is used to collect purified water and then withdraw it to the ground or use it for technical needs. When using additional mechanical treatment, water is driven through a layer of expanded clay or sandstone.
Deep biological treatment station
In fact, this system completely repeats the entire path that wastewater goes into the environment. As a result of the operation of the station, all sewage is decomposed into industrial water with a purification degree of about 98% and sludge, which can be used as fertilizer or processed into biofuel. The difference with natural cleaning is that the whole process is completely controlled - the same sludge is not collected on the banks of water bodies, but is used as intended.
The design of the deep bio-treatment station does not differ in principle by a complex device and, if desired, it can be done independently, although the dimensions of a home-made device will most likely be lost to those manufactured under industrial conditions.
It consists of several compartments:
1 Receiving chamber. Sewers from sewers get here.
2 Secondary sump chamber.
3 Aerotank. Capacity in which continuous air injection is organized.
4 Bioreactor. A hollow tank, loaded with a special float on which aerobic bacteria are populated.
5 Final sump.
This is the simplest scheme - in some cases, systems with two aeration tanks and a large number of intermediate sedimentation tanks are used.
The principle of operation of the deep cleaning station becomes clear if we consider the operation of each camera separately.
Sewage from the sewer enters the chamber of the first sump.It separates the bulk of the sediment, which undergoes primary decomposition, due to the effects of anaerobic bacteria living on the bottom. Part of the mass will remain in the chamber in the form of sludge, and the other will eventually fall into the next compartment.
Oxygen can partially enter the secondary chamber, therefore aerobic and anaerobic bacteria simultaneously act on the effluents in it.
After filling the secondary sump, the effluents enter the aeration tank - there they are actively saturated with air, which is specially injected into the chamber by the compressor. As a result, a mixture of liquid particles of sludge and air bubbles floating in it is formed. It is most convenient to feed it into the next compartment with an airlift - it starts when the tank is full.
In the next chamber, plastic floats, on which aerobic microorganisms live, float on partially clarified drains. They process the bulk of organic substances, finally decomposing them into sludge suitable for fertilizer and clean industrial water.
The last compartment is used to store purified water, at the same time working as the final sump.
Selection of a septic tank depending on operating conditions and soil type
Installing a septic tank is not the cheapest pleasure, so before deciding on the choice of a particular design, you need to take into account their operational characteristics, seasonal demand and the features of the soil in which they will be installed.
What septic tanks are better to use for summer cottages
If the financial issue is not the main one, then for a house with permanent residence, the best option would be a deep biological treatment station. Despite the high initial price, it has a rather short payback period - it is better than a septic tank for cottages without pumping waste. Of course, the waste will be when using any cleaning system, but in this case they can be removed independently and used as fertilizer.
The main advantage of this system is the ability to use in any conditions, as the result of work is clean water and environmentally friendly sludge. The disadvantages include the possibility of the death of bacteria, if you do not use the sewage system for about two weeks, and intolerance by microorganisms of chlorine and similar active chemical compounds.
All other cleaning systems will be more expensive to operate, which over time will block the original price, or harm the environment, as they can not provide an adequate level of cleaning.
Which septic tank is better for a summer residence with non-permanent residence
In this case, everything depends on the period of time during which the sewerage is not actively used in the country. If the owners come for the whole summer, then you can consider the option with a biological treatment system or with a biofilter, but before your arrival you will have to spend about 15 cu to buy a new batch of bacteria.
In any other case, you can use the remaining types of septic tanks, focusing more on the nature of the soil in which it will be installed. It is also worth considering that the design of the septic tank with an infiltrator and an intermediate well allows it to withstand significant salvo discharge of sewage.
What septic tanks are best used on sandy soils
The most affordable option is the use of a septic tank with a filtration well. Its advantages include simplicity of design, complete non-volatility and slow filling of containers. If there is space for installation, you can use a septic tank with a filtration field or an infiltrator. All of these septic tanks are designed to drain treated water directly into the soil and if it is sandy, then this is the best option for their operation.
What septic tanks are suitable for use on clay soils
In addition to universal biological treatment systems, on soils with poor water absorption, an optimal solution would be to use a septic tank with an infiltrator and an intermediate well. This choice is due to the ability of the septic tank to inhibit the reverse flow of water if it does not have time to soak into the soil. When installing such a system, one must remember about its volatility - for the pump to work, electricity is needed.
In case of emergency, on clay soils, you can use a septic tank with a filtration well, but at the same time it will have to be cleaned more often than the estimated time. The use of a septic tank with a filtration field is not recommended, since there is a likelihood of a reverse outflow in the tanks of the settlers.
Which septic tanks should be used with a high level of groundwater
A high level of groundwater often leads to the same problems as soils with low absorption of liquids - when filling the filter elements, the water from them will go back to the septic tank. This makes it impossible to use structures in which drains pass from section to section by gravity.
The most suitable options in this case are only two:
- a septic tank with an infiltrator with an intermediate well in which there is a check valve, and an electric pump supplies water to the infiltrator;
- any of the biological treatment systems - all of them are powered by electricity, and their tanks are sealed, and do not allow groundwater to enter the system.
Comparison of septic tanks by basic parameters
In order to better understand which septic tank for a summer residence is better, in each case, compare them with each other according to the main characteristics.
 |  |  |  |  | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Septic tank with a filtration well | Septic tank with a filtration field | Septic tank with infiltrator | Septic tank with biofilter | Deep biological treatment station | |||||||
| Septic tank cost | Low | Average | Average | Average | High | ||||||
| Cost of arrangement | Low | High | High | Average | Average | ||||||
| Installation complexity | Average complexity | High labor input | High labor input | Average complexity | Average complexity | ||||||
| Frequency of service | Wastewater treatment every 6 months, backfill replacement every 5 - 7 years | Pillow replacement every 10 years | Pillow replacement every 10 years | Sludge is extracted every six months; biological products must be added. | Sludge is extracted every six months; all operations can be carried out manually | ||||||
| The degree of sewage treatment | Low | Low | Low | Average | High | ||||||
| System energy independence | Non-volatile | Non-volatile | May be volatile | Non-volatile | Volatile | ||||||
The cost of a septic tank and its arrangement
There is a simple rule - the simpler, the cheaper. Least of all money will have to be spent on a regular septic tank with a filtration well, and arranging a system with a filtration field or an infiltrator will cost more. Biological treatment systems have the highest price, especially if you purchase an industrial-made device, but if used properly, the costs will quickly pay off.
Installation complexity
Here, the purchased biological treatment systems, which are often carried out by manufacturers in one building or several equal in size and connected in series, are unambiguously leading. For them, you just need to dig one hole and install the entire system into it.
It’s a little more difficult to install a septic tank with a filtration well, for which you need to dig a few holes, and put a pillow of sand and gravel at the bottom of the latter.
The most time-consuming to install can be considered septic tanks with a filtration field or an infiltrator. For each of them, it will be necessary to remove the soil from a sufficiently large area, lay sand and gravel (crushed stone) in the resulting pit, install filter elements and backfill everything with earth.
Installation of the infiltrator.
Installation of the filtration field.
Frequency of service
Any septic tank needs to be cleaned much less often than a cesspool - the more perfect the design, the less reason to call the scavengers:
Septic tank with a filtration well. The overflow tanks of the septic tanks themselves are cleaned about once every six months, and the rubble and sand at the bottom of the well must be changed every 5-7 years.
Septic tank with filtration field or infiltrator. Since purified water is discharged over a large area, it is enough to replace the pillow once every 10 years. The siltation time of sedimentation tanks depends entirely on their size and intensity of use of sewage.
Biological or deep treatment plants. It is sufficient to remove accumulated sludge once every six months, while all operations can be carried out manually.
The degree of sewage treatment
By the level of purification, all septic tanks are divided into devices for mechanical action on drains and combined - mechanical-biological. In the first case, the purification level will be about 70% - such water cannot be used even for irrigation, and only lawn grass is allowed to be planted over the filtration field or infiltrator. In the second case, the degree of wastewater treatment reaches 95-98% - these are normal parameters for industrial water, which can be used for irrigation or other technical needs.
System non-volatility
Of the presented systems, only two are volatile: a septic tank with an infiltrator with an intermediate well and a deep biological treatment station. In the first case, an electric drainage pump is used, and in the second, compressors plus airlift pumps. Depending on the power of the entire device, energy consumption can be from 1.5 to 30 kW per day.
