Biological wastewater treatment methods have several advantages, one of which is the ability to apply to large volumes of domestic and industrial waste. The main active link is microorganisms that feed on nitrogen, proteins, carbohydrates, fats, acids. Bacteria break down organics to neutral components - gas and water.
The device and principle of operation of the biological treatment plant
Preparing wastewater for reuse is one of the most pressing problems. Wastes include industrial waste, domestic and natural sedimentary waters. They must be brought to such a level of purification that it can be used for human needs without resorting to water intake from natural reservoirs.
Many methods have been proposed, but only one of them is completely safe and provides the degree of purification after which water can be used for domestic purposes - a deep biological treatment station for a country house, because it is precisely where there is no centralized drainage system that there is a problem with their disposal . After the final filtration at home, the water becomes potable.
Biological wastewater treatment scheme
The general scheme of the biological treatment plant is as follows:
- Sewer flows into the station through a sewer pipe. First they go through mechanical cleaning through grates, sand traps and grease traps. All of these mechanisms are built into the system.
- The liquid purified from solid particles enters the sump, where the bulk of the suspended particles settles to the bottom.
- There is a transfer or discharge to the secondary sump, from it to the sludge tank, where bacteria that eat organic matter work.
- The semi-purified liquid is driven through the aeration tank. It enriches the liquid with oxygen, and the water is also purified with the help of microorganisms. On the one hand, biomass from bacteria is supplied, on the other hand, water, which must be purified. Aerotank looks like a long corridor. Due to oxygenation, microorganisms multiply and their total mass at the output increases several times.
- Next, you need to separate the bacterial mass from purified water. For this, the liquid is driven into a sump. Biomass is a suspension with a concentration of microorganisms from 0.4 to 0.8%. Part of the suspension is disposed of, and part is left for further propagation and use in the process of running water through the aeration tank.
- The effluents are transferred to a mixer, where they are disinfected with chlorine.
- Further, the water can be used as technical or discharged into a natural body of water without danger to the local flora and fauna.
There are various configurations of biological stations operating both on electricity and by gravity.
For the cleaning process, with a different degree of contamination, a minimum number of microorganisms must be present in the water. It is also required to observe oxidative density, i.e. the amount of oxygen dissolved in water.
Advantages and disadvantages of SBO
At a fairly high cost of biological treatment plants, they have several advantages:
- economical use of electricity, the ability to work by gravity;
- the degree of water purification is close to 100%;
- long service life - more than 50 years;
- the station building is not subject to corrosion, as it is made of polypropylene - industrial plastic;
- no need to add biomass, as the technology allows you to use part of the activated sludge after settling for further purification of liquids;
- suitable for private houses, restaurants, industrial enterprises, apartment buildings and other institutions;
- it is simply mounted, does not require repair costs;
- installation is carried out only by the underground method, so the station does not occupy a place on the earth's surface.
The disadvantages of the system are manifested when the configuration of the treatment plant is not selected correctly. For example, runoff is carried out into the soil to the filtration fields, but the soil in the area does not absorb water at the speed provided by the station. In this case, siltation of the fields occurs and restoration work is necessary.
Once every 1-3 years, depending on the volume of the tank, it is necessary to carry out a complete cleaning and replacement of activated sludge. These are additional costs. However, if you consider how much it costs to constantly pump out the sewage using a sewer machine, installing a biological treatment plant will be a profitable solution.
If it is impossible to mount the pipes on a slope, you will have to put a pump for pumping waste water. This will result in electricity costs.
If drains arrive in small portions, the system works without failures. If you give a large volume of liquid at the same time or lower the chemistry into the sewer, microorganisms will suffer. They will die, and new ones will have to be populated and propagated over time. In such situations, water cannot be used, as it comes in untreated form. This point does not apply to all varieties of treatment plants, but only the cheapest.
Some systems do not have a fat protection function. Bacteria do not digest it, so when leaving the treatment plant, the water will be oily. In the kitchen you need to put extra grease traps.
Materials used
In the installation of biological treatment plants, plastic materials are used that are resistant to soil movement on the site and are able to withstand winter temperatures. The pipes connecting the tanks also use plastic, calculated according to the technical characteristics for external sewage.
There are models that involve the installation of plastic containers in a concrete frame. These are expensive structures, but sealed. Odor in the area with full sealing will not appear.
Mounting Features
So that the system does not create problems on the site, it is necessary to choose the right place for its installation. There are a set of rules that will help determine the location of the underground system:
- a septic tank is placed no closer than one meter to the foundation of the building;
- it is necessary to strictly observe the dimensions of the pit for the tank, since a decrease in the sand cushion causes it to be squeezed with soil and, as a result, damage to the walls, depressurization;
- a sand cushion is poured to the bottom or a concrete foundation is made due to the proximity of groundwater;
- pipes suitable for the septic tank are also sprinkled with sand to avoid deformation;
- takes into account the laying depth of sewer pipes, based on the climatic conditions of the area.
The first step is to prepare a pit and strengthen the walls. Install the tank, make a hole and connect the inlet and outlet pipes. Fill the gaps between the walls with sand, which is filled with water to seal.
Then, pipes connecting the septic tank with the house are laid in trenches. After testing the system, the trench is covered with sand.
Overview of biological treatment plants for a private home
On the market you can find biological treatment plants of the following brands:
- Topas;
- GRAF;
- Eurobion;
- Bioxy;
- Ergobox;
- SBR;
- NV;
- UPONOR;
- SANI;
- GRAFPicobell;
- Yunilos;
- EuroLos.
The cheapest, but not the most practical, are the bioseptics of Topas. The slightest excess of wastewater leads to malfunctioning of the treatment. It is not recommended to drain water to the site, especially if fat separators are not installed.Manufacturers themselves say that they would not drink such water, although a 98% degree of purification is claimed. This company uses many advertising tricks that provide sales, but as a result it turns out to be a waste of money for customers. The price of a biological treatment station for a private house Topas starts from 79 thousand rubles.
NV autonomous cleaning system is considered the most productive and reliable, starting with the materials of manufacture (fiberglass reinforced with a long-term warranty), ending with the technology of purification and water sludge. The technology of stockpile of activated sludge allows users to sometimes drain household chemicals into a septic tank without the risk of killing microorganisms irrevocably. Some of them are preserved and capable of reproduction.
SANI, GRAFPicobell biological treatment plants provide long-term functionality and uninterrupted operation. They are put on a par with the quality of the brand NV.
Owner reviews
Michael, Kazan: He put a septic tank with topop bacteria in his private house. Dissatisfied, because you have to throw out large amounts every 3 months for inspection. They advised a different brand in the store, but decided to take it cheaper, it turned out that a large load on it should not be given. You can immediately see how dirty the water flows into the ditch. It’s good that they didn’t do reuse - the filters in the house would have to be changed every day.
Eugene, Smolensk: They put Topas in the country. We are rare, so there are no special problems so far. In the summer we use purified water to irrigate the site. We were recommended to put a fat catcher - they did the right thing to agree. At the neighbors, through two houses, the water comes out clean, but oily. It turns out the bacteria do not dispose of it.
Marina, Voronezh: We have a big family - constantly someone bathes or cooks in the kitchen. The house is two-story, 3 bathrooms, 2 washing machines. They advised NV, they said that with the dumping of chemistry, bacteria will survive, but still try to use natural detergents. We are satisfied with the septic tank, it works without interruptions. We use water to wash the car and water the garden. Plants react normally.
