The principle of operation of treatment facilities. Types of treatment facilities

Every Russian city has a system of special facilities that are designed to treat wastewater containing a wide variety of mineral and organic compounds to such a state that they can be discharged into the environment without harming the environment. Modern treatment facilities for the city, which are developed and manufactured by Flotenk, are technically quite complex complexes consisting of several separate blocks, each of which performs a strictly defined function.

To order and calculate treatment facilities, send a request to E-mail: or call toll-free 8 800 700-48-87 Or fill out a questionnaire:

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Advantages of urban wastewater treatment plants manufactured by Flotenk

Development, production and installation of treatment facilities is one of the main specializations of the Flotenk company. Its systems have, as practice shows, many advantages over similar products manufactured by many other domestic and foreign firms. Among them, it should be noted the high efficiency of urban wastewater treatment plants from Flotenk, which is due to a carefully calculated, well-thought-out and well-realized design. In addition, they are distinguished by increased reliability and long service life, since their main components are made of durable and resistant to various kinds of adverse effects of fiberglass.

How is wastewater treated in the city?

Wastewater treatment of the city is carried out in stages. The effluents entering the sewage treatment plant through the sewer system first of all enter the unit, where the separation of the mechanical impurities contained in them is carried out. After that, the wastewater goes to biological treatment, during which most of the organic compounds, as well as nitrogen compounds, are removed from them. In the next, third block, wastewater is additionally treated, as well as their disinfection with either chlorine or ultraviolet radiation treatment. Once in the last block, urban wastewater settles, and a sediment is separated from it, which is subject to further treatment.

Wastewater treatment plants, which are developed and manufactured by Flotenk for cities, have blocks of mechanical wastewater treatment, in which specialized meshes with cells of very small sizes are installed to remove large enough debris. In addition, these blocks are also equipped with sand traps. They are containers of a sufficiently large volume, in which, due to a sharp decrease in the flow rate of wastewater, sand is deposited under the influence of gravity. These tanks are manufactured at Flotenk's own production facilities, have several components and are assembled directly at the installation site.

Biological treatment of urban wastewater is also carried out in special tanks, which are called aeration tanks. In them, a component such as activated sludge is added to the drains, which contains microorganisms that decompose various substances of organic origin. In order for the biological treatment process to go faster, air is pumped into the aeration tanks with the help of compressors.

Secondary clarifiers, to which wastewater is sent after biological treatment, are necessary in order to isolate the activated sludge contained in them, which is then sent back to the aeration tanks. In addition, these tanks are used for the disinfection of wastewater, which, at the end of this process, is sent to discharge points (most often these are open water bodies).

- This is a complex of special facilities designed to treat wastewater from the contaminants contained in them. Purified water is either used in the future, or discharged into natural reservoirs (Great Soviet Encyclopedia).

Each settlement needs effective treatment facilities. The operation of these complexes determines what water will enter the environment and how it will affect the ecosystem in the future. If liquid waste is not treated at all, then not only plants and animals will die, but the soil will also be poisoned, and harmful bacteria can enter the human body and cause serious consequences.

Each enterprise that has toxic liquid waste is obliged to deal with a system of treatment facilities. Thus, it will affect the state of nature, and improve the conditions of human life. If the treatment complexes work effectively, then the wastewater will become harmless when it enters the ground and water bodies. The size of treatment facilities (hereinafter referred to as O.S.) and the complexity of treatment are highly dependent on the contamination of wastewater and their volumes. In more detail about the stages of wastewater treatment and types of O.S. read on.

Stages of wastewater treatment

The most indicative in terms of the presence of stages of water purification are urban or local OS, designed for large settlements. It is domestic wastewater that is the most difficult to treat, as it contains heterogeneous pollutants.

For facilities for the purification of water from sewerage, it is characteristic that they line up in a certain sequence. Such a complex is called a line of treatment facilities. The scheme begins with mechanical cleaning. Here gratings and sand traps are most often used. This is the initial stage of the entire water treatment process.

It can be the remains of paper, rags, cotton wool, bags and other debris. After gratings, sand traps come into operation. They are necessary in order to retain sand, including large sizes.

Mechanical Stage Wastewater Treatment

Initially, all water from the sewer goes to the main pumping station in a special tank. This tank is designed to compensate for the increased load during peak hours. A powerful pump evenly injects the appropriate volume of water to pass through all stages of cleaning.

catch large debris over 16 mm - cans, bottles, rags, bags, food, plastic, etc. In the future, this garbage is either processed on site or taken to the places of processing of solid domestic and industrial waste. Lattices are a type of transverse metal beams, the distance between which is equal to several centimeters.

In fact, they catch not only sand, but also small pebbles, glass fragments, slag, etc. Sand rather quickly settles to the bottom under the influence of gravity. Then the settled particles are raked by a special device into a recess at the bottom, from where it is pumped out by a pump. The sand is washed and disposed of.

. Here all impurities that float to the surface of the water (fats, oils, oil products, etc.) are removed, etc. By analogy with a sand trap, they are also removed with a special scraper, only from the surface of the water.

4. Sumps- an important element of any line of treatment facilities. They release water from suspended solids, including helminth eggs. They can be vertical and horizontal, single-tier and two-tier. The latter are the most optimal, since at the same time the water from the sewer in the first tier is cleaned, and the sediment (silt) that has formed there is discharged through a special hole into the lower tier. How does the process of releasing water from the sewer from suspended solids take place in such structures? The mechanism is quite simple. Sedimentation tanks are large round or rectangular tanks where substances settle under the action of gravity.

To speed up this process, you can use special additives - coagulants or flocculants. They contribute to the adhesion of small particles due to a change in charge, larger substances are deposited faster. Thus, sedimentation tanks are indispensable facilities for purifying water from sewers. It is important to consider that with simple water treatment they are also actively used. The principle of operation is based on the fact that water enters from one end of the device, while the diameter of the pipe at the exit becomes larger and the fluid flow slows down. All this contributes to the deposition of particles.

mechanical wastewater treatment can be used depending on the degree of water pollution and the design of a particular treatment plant. These include: membranes, filters, septic tanks, etc.

If we compare this stage with conventional water treatment for drinking purposes, then in the latter version such facilities are not used, they are not necessary. Instead, the processes of clarification and discoloration of water occur. Mechanical cleaning is very important, as in the future it will allow more efficient biological cleaning.

Biological wastewater treatment plants

Biological treatment can be both an independent treatment facility and an important stage in a multi-stage system of large urban treatment facilities.

The essence of biological treatment is to remove various pollutants (organics, nitrogen, phosphorus, etc.) from water with the help of special microorganisms (bacteria and protozoa). These microorganisms feed on harmful contaminants contained in the water, thereby purifying it.

From a technical point of view, biological treatment is carried out in several stages:

- a rectangular tank, where water after mechanical cleaning is mixed with activated sludge (special microorganisms), which cleans it. Microorganisms are of 2 types:

• Aerobic using oxygen to purify water. When using these microorganisms, the water must be enriched with oxygen before it enters the aerotank.
• Anaerobic– NOT using oxygen for water purification.

It is necessary to remove unpleasantly smelling air with its subsequent purification. This workshop is necessary when the volume of wastewater is large enough and / or treatment facilities are located near settlements.

Here, water is purified from activated sludge by settling it. Microorganisms settle to the bottom, where they are transported to the pit with the help of a bottom scraper. To remove floating sludge, a surface scraper mechanism is provided.

The treatment scheme also includes sludge digestion. Of the treatment facilities, the methane tank is important. It is a tank for the digestion of sediment, which is formed during settling in two-tiered primary clarifiers. During the digestion process, methane is produced, which can be used in other technological operations. The resulting sludge is collected and transported to special sites for thorough drying. Sludge beds and vacuum filters are widely used for sludge dehydration. After that, it can be disposed of or used for other needs. Fermentation occurs under the influence of active bacteria, algae, oxygen. Biofilters may also be included in the sewerage water treatment scheme.

It is best to place them before the secondary settling tanks, so that substances that have been carried away with the flow of water from the filters can be deposited in the settling tanks. It is advisable to use so-called pre-aerators to speed up cleaning. These are devices that contribute to the saturation of water with oxygen to accelerate the aerobic processes of oxidation of substances and biological treatment. It should be noted that the purification of water from the sewerage is conditionally divided into 2 stages: preliminary and final.

The system of treatment facilities may include biofilters instead of filtration and irrigation fields.

- These are devices where wastewater is purified by passing through a filter containing active bacteria. It consists of solid substances, which can be used as granite chips, polyurethane foam, polystyrene and other substances. A biological film consisting of microorganisms forms on the surface of these particles. They decompose organic matter. Biofilters need to be cleaned periodically as they get dirty.

Wastewater is fed into the filter in a dosed manner, otherwise a large pressure can kill beneficial bacteria. After biofilters, secondary clarifiers are used. The sludge formed in them enters partly into the aerotank, and the rest of it goes to the sludge thickeners. The choice of one or another method of biological treatment and the type of treatment facilities largely depends on the required degree of wastewater treatment, topography, soil type and economic indicators.

Post-treatment of wastewater

After passing the main stages of treatment, 90-95% of all contaminants are removed from wastewater. But the remaining pollutants, as well as residual microorganisms and their metabolic products, do not allow this water to be discharged into natural reservoirs. In this regard, various systems for post-treatment of wastewater were introduced at treatment facilities.

In bioreactors, the following pollutants are oxidized:

• organic compounds that were "too tough" for microorganisms,
• these microorganisms themselves
• ammonium nitrogen.

This happens by creating conditions for the development of autotrophic microorganisms, i.e. converting inorganic compounds into organic ones. For this, special plastic charging disks with a high specific surface area are used. Simply put, these discs have a hole in the center. Intensive aeration is used to speed up the processes in the bioreactor.

Filters purify water with sand. The sand is continuously updated automatically. Filtration is carried out at several installations by supplying water to them from the bottom up. In order not to use pumps and not to waste electricity, these filters are installed at a level lower than other systems. Filter washing is designed in such a way that it does not require a large amount of water. Therefore, they do not occupy such a large area.

Disinfection of water with ultraviolet light

Disinfection or disinfection of water is an important component that ensures its safety for the reservoir into which it will be discharged. Disinfection, that is, the destruction of microorganisms, is the final step in the purification of sewage effluents. A wide variety of methods can be used for disinfection: ultraviolet irradiation, alternating current, ultrasound, gamma irradiation, chlorination.

UVR is a very effective method by which approximately 99% of all microorganisms are destroyed, including bacteria, viruses, protozoa, and helminth eggs. It is based on the ability to destroy the bacterial membrane. But this method is not widely used. In addition, its effectiveness depends on the turbidity of the water, the content of suspended solids in it. And UVI lamps quite quickly become covered with a coating of mineral and biological substances. To prevent this, special emitters of ultrasonic waves are provided.

The most commonly used method of chlorination after sewage treatment plants. Chlorination can be different: double, superchlorination, with preammonization. The latter is necessary to prevent an unpleasant odor. Superchlorination involves exposure to very large doses of chlorine. Dual action is that chlorination is carried out in 2 stages. This is more typical for water treatment. The method of chlorinating water from the sewer is very effective, in addition, chlorine has an aftereffect that other cleaning methods cannot boast of. After disinfection, the waste is discharged into a reservoir.

Phosphate removal

Phosphates are salts of phosphoric acids. They are widely used in synthetic detergents (washing powders, dishwashing detergents, etc.). Phosphates, getting into water bodies, lead to their eutrophication, i.e. turning into a swamp.

Wastewater treatment from phosphates is carried out by dosed addition of special coagulants to water in front of biological treatment facilities and in front of sand filters.

Auxiliary premises of treatment facilities

Aeration shop

- this is an active process of saturating water with air, in this case by passing air bubbles through the water. Aeration is used in many processes in wastewater treatment plants. Air is supplied by one or more blowers with frequency converters. Special oxygen sensors regulate the amount of air supplied so that its content in the water is optimal.

Disposal of excess activated sludge (microorganisms)

At the biological stage of wastewater treatment, excess sludge is formed, since microorganisms actively multiply in the aeration tanks. Excess sludge is dehydrated and disposed of.

The dehydration process takes place in several stages:

1. In excess sludge is added special reagents, which stop the activity of microorganisms and contribute to their thickening
2. AT sludge thickener the sludge is compacted and partially dehydrated.
3. On the centrifuge the sludge is squeezed out and the remaining moisture is removed from it.
4. Inline dryers with the help of continuous circulation of warm air, the sludge is finally dried. The dried sludge has a residual moisture content of 20-30%.
5. Then ooze packed in sealed containers and disposed of
6. The water removed from the sludge is sent back to the beginning of the purification cycle.

Air cleaning

Unfortunately, the sewage treatment plant does not smell the best. Particularly smelly is the stage of biological wastewater treatment. Therefore, if the treatment plant is located near settlements or the volume of wastewater is so large that there is a lot of bad-smelling air, you need to think about cleaning not only water, but also air.

Air purification, as a rule, takes place in 2 stages:

1. Initially, polluted air is fed into bioreactors, where it comes into contact with specialized microflora adapted for the utilization of organic substances contained in the air. It is these organic substances that cause the bad smell.
2. The air goes through the stage of disinfection with ultraviolet light to prevent these microorganisms from entering the atmosphere.

Laboratory at the wastewater treatment plant

All water that leaves the treatment plant must be systematically monitored in the laboratory. The laboratory determines the presence of harmful impurities in the water and the compliance of their concentration with the established standards. In case of exceeding one or another indicator, the workers of the treatment plant conduct a thorough inspection of the corresponding stage of treatment. And if a problem is found, they fix it.

Administrative and amenity complex

The personnel serving the treatment plant can reach several tens of people. For their comfortable work, an administrative and amenity complex is being created, it includes:

• Equipment repair shops
• Laboratory
• control room
• Offices of administrative and managerial personnel (accounting, personnel service, engineering, etc.)
• Head office.

Power supply O.S. performed according to the first category of reliability. Since the long stoppage of O.S. due to lack of electricity can cause the output of O.S. out of service.

To prevent emergency situations, the power supply of O.S. comes from several independent sources. In the department of the transformer substation, the input of a power cable from the city power supply system is provided. And also the input of an independent source of electric current, for example, from a diesel generator, in case of an accident in the city power grid.

Conclusion

Based on the foregoing, it can be concluded that the scheme of treatment facilities is very complex and includes various stages of wastewater treatment from sewers. First of all, you need to know that this scheme applies only to domestic wastewater. If there are industrial effluents, then in this case they additionally include special methods that will be aimed at reducing the concentration of hazardous chemicals. In our case, the cleaning scheme includes the following main stages: mechanical, biological cleaning and disinfection (disinfection).

Mechanical cleaning begins with the use of gratings and sand traps, in which large debris (rags, paper, cotton wool) is retained. Sand traps are needed to settle excess sand, especially coarse sand. This is of great importance for the next steps. After gratings and grit traps, the sewerage treatment plant scheme includes the use of primary clarifiers. Suspended matter settles in them under the force of gravity. Coagulants are often used to speed up this process.

After the settling tanks, the filtration process begins, which is carried out mainly in biofilters. The mechanism of action of the biofilter is based on the action of bacteria that destroy organic matter.

The next stage is secondary settling tanks. In them, the silt, which was carried away with the current of the liquid, settles. After them, it is advisable to use a digester, in which the sediment is fermented and transported to sludge sites.

The next stage is biological treatment with the help of an aeration tank, filtration fields or irrigation fields. The final step is disinfection.

Types of treatment facilities

A variety of facilities are used for water treatment. If it is planned to carry out these works in relation to surface waters immediately before they are supplied to the distribution network of the city, then the following facilities are used: sedimentation tanks, filters. A wider range of devices can be used for wastewater: septic tanks, aeration tanks, digesters, biological ponds, irrigation fields, filtration fields, and so on. Wastewater treatment plants are of several types depending on their purpose. They differ not only in the volume of treated water, but also in the presence of stages of its purification.

City wastewater treatment plant

Data from O.S. are the largest of all, they are used in large metropolitan areas and cities. Such systems use particularly effective liquid treatment methods, such as chemical treatment, methane tanks, flotation units. They are designed to treat municipal wastewater. These waters are a mixture of domestic and industrial wastewater. Therefore, there are a lot of pollutants in them, and they are very diverse. The waters are purified to the standards for discharge into a reservoir for fishery purposes. The standards are regulated by the order of the Ministry of Agriculture of Russia dated December 13, 2016 No. 552 “On approval of water quality standards for water bodies of fishery significance, including standards for maximum permissible concentrations of harmful substances in the waters of water bodies of fishery significance”.

On O.S. data, as a rule, all stages of water purification described above are used. The most illustrative example is the Kuryanovsk treatment facilities.

Kuryanovskie O.S. are the largest in Europe. Its capacity is 2.2 million m3/day. They serve 60% of wastewater in the city of Moscow. The history of these objects goes back to the distant 1939.

Local treatment facilities

Local treatment facilities are facilities and devices designed to treat the subscriber's wastewater before they are discharged into the public sewerage system (the definition is given by Decree of the Government of the Russian Federation of February 12, 1999 No. 167).

There are several classifications of local O.S., for example, there are local O.S. connected to the central sewerage and autonomous. Local O.S. can be used on the following objects:

• In small towns
• In the settlements
• In sanatoriums and boarding houses
• At car washes
• On household plots
• At manufacturing plants
• And on other sites.

Local O.S. can be very different from small units to permanent structures that are serviced daily by qualified personnel.

Treatment facilities for a private house.

Several solutions are used for the disposal of wastewater from a private house. All of them have their advantages and disadvantages. However, the choice always remains with the owner of the house.

1. Cesspool. In truth, this is not even a sewage treatment plant, but simply a reservoir for temporary storage of wastewater. When the pit is filled, a sewage truck is called in, which pumps out the contents and transports it for further processing.

This archaic technology is still used today because of its cheapness and simplicity. However, it also has significant drawbacks, which, at times, negate all its advantages. Wastewater can enter the environment and groundwater, thereby polluting them. For a sewage truck, it is necessary to provide for a normal entrance, since it will have to be called quite often.

2. Drive. It is a container made of plastic, fiberglass, metal or concrete, where wastewater is drained and stored. Then they are pumped out and disposed of by a sewage machine. The technology is similar to a cesspool, but the waters do not pollute the environment. The disadvantage of such a system is the fact that in the spring, with a large amount of water in the soil, the drive can be squeezed out to the surface of the earth.

3. Septic tank- is a large container, in which substances such as coarse dirt, organic compounds, stones and sand precipitate, and elements such as various oils, fats and petroleum products remain on the surface of the liquid. The bacteria that live inside the septic tank extract oxygen for life from the precipitated sludge, while reducing the level of nitrogen in the wastewater. When the liquid leaves the sump, it becomes clarified. Then it is cleaned with bacteria. However, it is important to understand that phosphorus remains in such water. For the final biological treatment, irrigation fields, filtration fields or filter wells can be used, the operation of which is also based on the action of bacteria and activated sludge. It will not be possible to grow plants with a deep root system in this area.

A septic tank is very expensive and can take up a large area. It should be borne in mind that this is a facility that is designed to treat a small amount of domestic wastewater from the sewer. However, the result is worth the money spent. The septic tank device is more clearly shown in the figure below.

4. Stations for deep biological treatment are already a more serious treatment plant, unlike a septic tank. This device requires electricity to operate. However, the quality of water purification is up to 98%. The design is quite compact and durable (up to 50 years of operation). To service the station at the top, above the ground, there is a special hatch.

Stormwater treatment plants

Despite the fact that rainwater is considered quite clean, however, it collects various harmful elements from asphalt, roofs and lawns. Garbage, sand and oil products. In order to prevent all this from falling into the nearest reservoirs, stormwater treatment facilities are being created.

In them, water undergoes mechanical purification in several stages:

1. Sump. Here, under the influence of the gravity of the Earth, large particles settle to the bottom - pebbles, glass fragments, metal parts, etc.
2. thin layer module. Here, oils and oil products are collected on the surface of the water, where they are collected on special hydrophobic plates.
3. Sorption fiber filter. It captures everything that the thin layer filter missed.
4. coalescence module. It contributes to the separation of particles of oil products that float to the surface, the size of which is greater than 0.2 mm.
5. Coal filter aftertreatment. It finally rids the water of all oil products that remain in it after passing through the previous stages of purification.

Design of treatment facilities

Design O.S. determine their cost, choose the right treatment technology, ensure the reliability of the structure, bring wastewater to quality standards. Experienced specialists will help you find effective plants and reagents, draw up a wastewater treatment scheme and put the plant into operation. Another important point is the preparation of a budget that will allow you to plan and control costs, as well as make adjustments if necessary.

For the project O.S. the following factors are strongly influenced:

• Waste water volumes. The design of facilities for a personal plot is one thing, but the design of facilities for wastewater treatment of a cottage village is another. Moreover, it must be taken into account that the possibilities of O.S. must be greater than the current amount of wastewater.
• Locality. Wastewater treatment facilities require the access of special vehicles. It is also necessary to provide for the power supply of the facility, the disposal of purified water, the location of the sewerage system. O.S. can occupy a large area, but they should not interfere with neighboring buildings, structures, road sections and other structures.
• Waste water pollution. Storm water treatment technology is very different from household water treatment.
• Required level of cleaning. If the customer wants to save on the quality of treated water, then it is necessary to use simple technologies. However, if it is necessary to discharge water into natural reservoirs, then the quality of treatment must be appropriate.
• Competence of the performer. If you order O.S. from inexperienced companies, then get ready for unpleasant surprises in the form of an increase in construction estimates or a septic tank that floated up in the spring. This happens because the project forgets to include enough critical points.
• Technological features. The technologies used, the presence or absence of treatment stages, the need to build systems serving the treatment plant - all this should be reflected in the project.
• Other. It is impossible to foresee everything in advance. As the treatment plant is being designed and installed, various changes may be made to the draft plan that could not have been foreseen at the initial stage.

Stages of designing a treatment plant:

1. Preliminary work. They include studying the object, clarifying the wishes of the customer, analyzing wastewater, etc.
2. Collection of permits. This item is usually relevant for the construction of large and complex structures. For their construction, it is necessary to obtain and agree on the relevant documentation from supervisory authorities: MOBVU, MOSRYBVOD, Rosprirodnadzor, SES, Hydromet, etc.
3. Choice of technology. Based on paragraphs 1 and 2, the necessary technologies used for water purification are selected.
4. Drawing up a budget. Construction costs O.S. must be transparent. The customer must know exactly how much the materials cost, what is the price of the installed equipment, what wage fund for workers, etc. You should also take into account the cost of subsequent maintenance of the system.
5. cleaning efficiency. Despite all calculations, the cleaning results may be far from desired. Therefore, already at the planning stage, O.S. it is necessary to conduct experiments and laboratory studies that will help to avoid unpleasant surprises after construction is completed.
6. Development and approval of project documentation. To start the construction of treatment facilities, it is necessary to develop and agree on the following documents: a project for a sanitary protection zone, a draft standard for permissible discharges, and a draft for maximum permissible emissions.

Installation of treatment facilities

After the project O.S. has been prepared and all the necessary permits have been obtained, the installation stage begins. Although the installation of a country septic tank is very different from the construction of a treatment plant in a cottage village, they still go through several stages.

First, the terrain is being prepared. A pit is being dug for the installation of a treatment plant. The floor of the pit is covered with sand and tamped or concreted. If the treatment plant is designed for a large amount of wastewater, then, as a rule, it is built on the surface of the earth. In this case, the foundation is poured and a building or structure is already installed on it.

Secondly, the installation of equipment is carried out. It is installed, connected to the sewerage and drainage system, to the electrical network. This stage is very important because it requires the personnel to know the specifics of the operation of the configured equipment. It is improper installation that most often causes equipment failure.

Thirdly, checking and handing over the object. After installation, the finished treatment plant is tested for the quality of water treatment, as well as for the ability to work in conditions of increased load. After checking O.S. is handed over to the customer or his representative, and, if necessary, passes the procedure of state control.

Maintenance of treatment facilities

Like any equipment, a sewage treatment plant also needs maintenance. First of all from O.S. it is necessary to remove large debris, sand, as well as excess sludge that are formed during cleaning. On large O.S. the number and type of elements to be removed can be much larger. But in any case, they will have to be removed.

Secondly, the performance of the equipment is checked. Malfunctions in any element can be fraught not only with a decrease in the quality of water purification, but also with the failure of all equipment.

Thirdly, in case of detection of a breakdown, the equipment is subject to repair. And it's good if the equipment is under warranty. If the warranty period has expired, then the repair of O.S. will have to be done at your own expense.

Today we will once again focus on a topic close to each of us without exception :)

Most people don't think about what happens to what they flush when they press the toilet button. Leaked and flowed away, that's business. In such a large city as Moscow, no less than four million cubic meters of sewage flows into the sewer system every day. This is about the same as the amount of water flowing in the Moskva River in a day in front of the Kremlin. All this huge volume of waste water needs to be cleaned and this task is very difficult.

There are two largest wastewater treatment plants in Moscow, approximately the same size. Each of them cleans up half of what Moscow "produces". I'm already talking about the Kuryanovsky station. Today I will talk about the Lyubertsy station - we will again go over the main stages of water purification, but we will also touch on one very important topic - how at treatment stations they fight unpleasant odors with the help of low-temperature plasma and perfume industry waste and why this problem has become more relevant than ever .

To start, a little history. For the first time, sewerage "came" to the area of ​​modern Lyubertsy at the beginning of the 20th century. Then the Lyubertsy irrigation fields were created, on which sewage, according to the old technology, seeped through the ground and was thereby purified. Over time, this technology became unacceptable for the ever-increasing amount of wastewater, and in 1963 a new treatment plant, the Lyuberetskaya, was built. A little later, another station was built - Novoluberetskaya, which actually borders on the first one and uses part of its infrastructure. In fact, now it is one large cleaning station, but consisting of two parts - the old and the new.

Let's look at the map - on the left, in the west - the old part of the station, on the right, in the east - the new one:

The area of ​​the station is huge, in a straight line from corner to corner about two kilometers.

As it is not difficult to guess, there is a smell coming from the station. Previously, few people worried about it, but now this problem has become relevant for two main reasons:

1) When the station was built, in the 60s, almost no one lived around it. There was a small village nearby, where the station workers themselves lived. Then this area was far, far from Moscow. Right now there is a lot of building going on. The station is actually surrounded by new buildings from all sides and there will be even more of them. New houses are being built even on the former sludge sites of the station (fields where the sludge left over from wastewater treatment was brought). As a result, residents of nearby houses are forced to periodically sniff "sewer" smells, and of course they constantly complain.

2) Sewer water has become more concentrated than before, in Soviet times. This happened due to the fact that the volume of water used recently has been strongly shrunk, while they did not go to the toilet less, but on the contrary - the population has grown. There are quite a few reasons why the "diluting" water has become much less:
a) the use of meters - water has become more economical to use;
b) the use of more modern plumbing - it is less and less common to see a running faucet or toilet bowl;
c) the use of more economical household appliances - washing machines, dishwashers, etc.;
d) the closure of a huge number of industrial enterprises that consumed a lot of water - AZLK, ZIL, Hammer and Sickle (partially), etc.
As a result, if the station during construction was calculated for a volume of 800 liters of water per person per day, now this figure is actually no more than 200. An increase in concentration and a decrease in flow led to a number of side effects - sediment began to be deposited in sewer pipes designed for a higher flow, leading to to bad odors. The station itself began to smell more.

To combat the smell, Mosvodokanal, which is in charge of the treatment facilities, is carrying out a phased reconstruction of the facilities, using several different methods of getting rid of odors, which will be discussed below.

Let's go in order, or rather, the flow of water. Waste water from Moscow enters the station through the Luberetsky sewer canal, which is a huge underground collector filled with sewage. The channel is gravity-flowing and runs at a very shallow depth for almost its entire length, and sometimes even above the ground. Its scale can be estimated from the roof of the administrative building of the treatment plant:

The width of the channel is about 15 meters (divided into three parts), the height is 3 meters.

At the station, the channel enters the so-called receiving chamber, from where it is divided into two streams - part goes to the old part of the station, part to the new one. The receiver looks like this:

The channel itself comes from the right-behind, and the stream divided into two parts leaves through the green channels in the background, each of which can be blocked by the so-called gate valve - a special shutter (dark structures in the photo). Here you can see the first innovation to combat odors. The receiving chamber is completely covered with metal sheets. Previously, it looked like a "pool" filled with fecal water, but now they are not visible, naturally, a solid metal coating almost completely covers the smell.

For technological purposes, only a very small hatch was left, lifting which you can enjoy the whole bouquet of smells. Hello from walsk :)

These huge gates allow you to block the channels coming from the receiving chamber if necessary.

From the receiving chamber there are two channels. They, too, were open quite recently, but now they are completely covered with a metal ceiling.

Under the ceiling, gases released from wastewater accumulate. This is mainly methane and hydrogen sulfide - both gases are explosive at high concentrations, so the space under the ceiling must be ventilated, but the next problem arises - if you just put a fan, then the whole point of the ceiling will simply disappear - the smell will get out. Therefore, to solve the problem, ICD "Horizon" has developed and manufactured a special unit for air purification. The installation is located in a separate booth and a ventilation pipe from the channel goes to it.

This installation is experimental, for testing the technology. In the near future, such installations will be massively installed at sewage treatment plants and at sewerage pumping stations, of which there are more than 150 units in Moscow and from which unpleasant odors also come. On the right in the photo - one of the developers and testers of the installation - Alexander Pozinovskiy.

The principle of operation of the installation is as follows:
polluted air is fed into four vertical stainless steel pipes from below. In the same pipes there are electrodes, to which a high voltage (tens of thousands of volts) is applied several hundred times per second, resulting in discharges and low-temperature plasma. When interacting with it, most smelling gases turn into a liquid state and settle on the walls of the pipes. A thin layer of water constantly flows down the walls of the pipes, with which these substances mix. Water circulates in a circle, the water tank is the blue container on the right, below in the photo. The purified air exits from the top of the stainless pipes and is simply released into the atmosphere.
For those who are more interested in more details - a photo of the stand, where everything is explained.

For patriots - the installation is completely designed and created in Russia, with the exception of the power stabilizer (below in the closet in the photo). High voltage part of the installation:

Since the installation is experimental, it has additional measuring equipment - a gas analyzer and an oscilloscope.

The oscilloscope shows the voltage across the capacitors. During each discharge, the capacitors are discharged and the process of their charge is clearly visible on the oscillogram.

Two tubes go to the gas analyzer - one takes air before installation, the other after. In addition, there is a tap that allows you to select the tube that is connected to the gas analyzer sensor. Alexander first shows us the "dirty" air. The content of hydrogen sulfide - 10.3 mg/m 3 . After switching the tap - the content drops to almost zero: 0.0-0.1.

Each of the channels is also blocked by a separate gate. Generally speaking, there are a huge number of them at the station - they stick out here and there :)

After cleaning from large debris, the water enters the sand traps, which, again, it is not difficult to guess from the name, are designed to remove small solid particles. The principle of operation of sand traps is quite simple - in fact, it is a long rectangular tank in which water moves at a certain speed, as a result, the sand simply has time to settle. Also, air is supplied there, which contributes to the process. From below, the sand is removed using special mechanisms.

As is often the case in technology, the idea is simple, but the execution is complex. So here - visually, this is the most "fancy" design on the way of water purification.

Sand traps were chosen by seagulls. In general, there were a lot of seagulls at the Lyubertsy station, but it was on the sand traps that they were the most.

I enlarged the photo already at home and laughed at their appearance - funny birds. They are called lake gulls. No, they don’t have a dark head because they constantly dip it where they don’t need it, it’s just such a design feature :)
Soon, however, it will not be easy for them - many open water surfaces at the station will be covered.

Let's get back to technology. In the photo - the bottom of the sand trap (not working at the moment). It is there that the sand settles and from there it is removed.

After sand traps, water again enters the common channel.

Here you can see what all the channels at the station looked like before they were covered. This channel is shutting down right now.

The frame is made of stainless steel, like most metal structures in the sewer. The matter is that in the sewerage very aggressive environment - water full of any substances, 100% humidity, gases promoting corrosion. Ordinary iron very quickly turns into dust in such conditions.

Work is being carried out directly above the existing channel - since this is one of the two main channels, it cannot be turned off (Muscovites will not wait :)).

In the photo there is a small level difference, about 50 centimeters. The bottom in this place is made of a special shape to dampen the horizontal speed of the water. As a result - very active seething.

After sand traps, water enters the primary sedimentation tanks. In the photo - in the foreground is a chamber into which water enters, from which it enters the central part of the sump in the background.

The classic sump looks like this:

And without water - like this:

Dirty water enters from the hole in the center of the sump and enters the general volume. In the sump itself, the suspension contained in the dirty water gradually settles to the bottom, along which the sludge rake is constantly moving, fixed on a truss rotating in a circle. The scraper rakes the sediment into a special annular tray, and from it, in turn, it falls into a round pit, from where it is pumped out through a pipe by special pumps. Excess water flows into the channel laid around the sump and from there into the pipe.

Primary clarifiers are another source of unpleasant odors in the plant, as they they contain actually dirty (purified only from solid impurities) sewer water. In order to get rid of the smell, Moskvodokanal decided to cover the sedimentation tanks, but then a big problem arose. The sump diameter is 54 meters (!). Photo with a person for scale:

Moreover, if you make a roof, then, firstly, it must withstand the snow load in winter, and secondly, it must have only one support in the center - it is impossible to make supports above the sump itself, because. there is a farm going on all the time. As a result, an elegant decision was made - to make the floor floating.

The ceiling is assembled from floating stainless steel blocks. Moreover, the outer ring of blocks is fixed motionless, and the inner part rotates afloat, together with the truss.

This decision turned out to be very successful, because. firstly, there is no problem with the snow load, and secondly, there is no air volume that would have to be ventilated and additionally cleaned.

According to Mosvodokanal, this design reduced odorous gas emissions by 97%.

This settling tank was the first and experimental one where this technology was tested. The experiment was recognized as successful, and now other sedimentation tanks are being covered in a similar way at the Kuryanovskaya station. Over time, all primary clarifiers will be covered in this way.

However, the process of reconstruction is lengthy - it is impossible to turn off the entire station at once, the settling tanks can only be reconstructed one after another, turning off one by one. And yes, it takes a lot of money. Therefore, until all the sedimentation tanks are covered, the third method of dealing with odors is used - spraying neutralizing substances.

Special atomizers were installed around the primary clarifiers, which create a cloud of odor neutralizing substances. The substances themselves smell not to say very pleasant or unpleasant, but rather specific, however, their task is not to mask the smell, but to neutralize it. Unfortunately, I did not remember the specific substances that are used, but as they said at the station, these are waste products from the perfume industry in France.

For spraying, special nozzles are used that create particles with a diameter of 5-10 microns. The pressure in the pipes, if I'm not mistaken, is 6-8 atmospheres.

After the primary settling tanks, water enters the aerotanks - long concrete tanks. They supply a huge amount of air through pipes, and also contain activated sludge - the basis of the entire method of biological water treatment. Activated sludge recycles "waste" and multiplies rapidly. The process is similar to what happens in nature in water bodies, but it proceeds many times faster due to warm water, a large amount of air and silt.

Air is supplied from the main machine room, where the turbo blowers are installed. Three turrets above the building are air intakes. The process of supplying air requires a huge amount of electricity, and the interruption of the supply of air leads to catastrophic consequences, because. activated sludge dies very quickly, and its recovery can take months (!).

Aerotanks, oddly enough, do not particularly exude strong unpleasant odors, so it is not planned to cover them.

This photo shows how dirty water enters the aerotank (dark) and mixes with activated sludge (brown).

Some of the facilities are currently disabled and mothballed, for the reasons I wrote about at the beginning of the post - the decrease in water flow in recent years.

After the aerotanks, the water enters the secondary settling tanks. Structurally, they completely repeat the primary ones. Their purpose is to separate activated sludge from already purified water.

Mothballed secondary clarifiers.

Secondary settling tanks do not smell - in fact, there is already clean water.

The water collected in the annular trough of the sump flows into the pipe. Part of the water undergoes additional UV disinfection and merges into the Pekhorka River, while part of the water goes through an underground channel to the Moskva River.

The settled activated sludge is used to produce methane, which is then stored in semi-underground tanks - methane tanks and used at its own thermal power plant.

The spent sludge is sent to sludge sites in the Moscow region, where it is additionally dehydrated and either buried or burned.

Lastly, a panorama of the station from the roof of the administrative building. Click to enlarge.

I express my deep gratitude for the invitation to the press service Mosvodokanal, as well as separately to Alexander Churbanov - director of the Lyubertsy treatment facilities. Thanks

The waste disposal system is an integral part of any city. It is she who provides the residential area, the normal functioning and compliance with sanitary standards in urban conditions. Wastewater that enters urban wastewater treatment plants contains a wide variety of organic and mineral compounds that can cause enormous damage to the environment if not properly disposed of.

The treatment plant includes four special treatment units. The first mechanical cleaning unit is used to remove sand and large debris (as a rule, large waste screened out at the first stage is much easier to dispose of). Then, at the next stage, in another block, a complete biological treatment takes place, and at the same time nitrogen compounds and the maximum possible amount of organic compounds are removed. After that, in the third block, further post-treatment of waste is already taking place - they are cleaned at a deeper level and disinfected. And in the fourth block, the process of processing the remaining precipitation takes place. Further, in order to better understand the essence of the process, we will consider in more detail how exactly this happens.

Due to mechanical, physical, chemical and biological treatment, sediment is separated from polluted water, which is then screened out in settling tanks specially designed for this purpose, and then, when activated sludge is formed, it passes into secondary settling tanks. Activated sludge is a very viscous substance that contains various simple organisms, bacteria and flakes formed from various chemical compounds. The sludge screened out by the settling tanks has almost one hundred percent moisture, but it is incredibly difficult to remove excess moisture, since the substances are highly bound together and have a low moisture yield. With the help of special sludge thickeners, the sludge is processed and compacted by two to three percent.

Unfortunately, the resulting substance cannot be used as fertilizer, because, despite the fact that potassium, nitrogen and phosphorus are present in activated sludge, they are poorly absorbed by plants, and in addition to microorganisms dangerous to humans, it also contains helminth eggs. Next, we will consider in more detail the types and principles of operation of facilities for the treatment of urban wastewater. In treatment facilities for mechanical water treatment, to remove sand and large debris, specialized meshes or strainers with cells no larger than two millimeters are used. For finer sand, sand traps are used. This is a completely mechanized procedure. Structures for mechanical cleaning look like eleven meters high and up to twenty-two meters in diameter, reservoirs created on the basis of oil. From above they are closed with lids and equipped with a ventilation system. In lighting and heating, such structures need minimal quantities, since the largest volume in it is occupied by wastewater, for which it is not necessary to raise the temperature (it should be in the range of about twelve to sixteen degrees).

Biological treatment involves complex chemical processes that oxidize and break down liquids, using pumps that transport contaminated water from one area to another. In addition, the system is equipped with an anaerobic stabilizer that contains a sludge thickener. Currently, various types of treatment facilities are used in the city, local, which are designed for private and country houses, and industrial ones, which are necessary in order to purify water from industrial waste.

With particular strict observance of environmental standards, they treat enterprises that produce any type of product (especially those from whose activities waste heavy metals and chemical compounds remain). Therefore, only after preliminary treatment, waste from industrial enterprises associated with the production of chemical, light, oil refining and other industries can be discharged into the central sewage system or reused. What processes should be carried out when treating water from an industrial enterprise is determined by the industry. The site that is used for the construction of large ones must be selected taking into account the convenient access of vehicles, the presence of a reservoir into which it is planned to discharge already purified waters and the features of the terrain (in particular, the composition of the soil and the level of groundwater).

Since the treatment plant is a structure that can have a direct impact on the environment, it must comply with strictly defined standards and norms. The perimeter of a wastewater treatment plant must always be enclosed by a fence, and only urban-made tanks are used on the station itself. In addition, the treatment facilities are subject to strict control by the Ministry of Ecology and Bioresources, which arranges inspections of all facilities at the station.

Most users of a modern system do not think about where water flows from a sink or toilet. Some concern arises if a blockage has formed, and the water does not want to flow away. But usually this problem is quite easily solved - with the help of a plunger or household chemicals such as "Mole". But what happens to the drains after they have left the field of view?

Residents of cities and large settlements who have a connection to the main sewage system do not need to worry about this. Indigenous villagers often do not ask such a question at all, habitually pouring a bucket of water from under the washstand under the nearest bush, using the village yard all their lives, washing clothes in the nearest pond and washing on Saturdays in their own, standing on the edge of the garden.

The question of sewerage in a country house arises when city dwellers, accustomed to its presence, end up in places where this blessing of civilization is not only not heard of, but it - this blessing - is not there. And it won't.

It is difficult for a city dweller who is accustomed to "city amenities" to refuse them - "both in the rain and in the snow" to go to the toilet on the street. So my husband and I, as former townspeople, had to face the need to build a local sewage system or solve the problem of domestic sewage in an alternative way. Well, in order to do something, you need to understand how it works.

Journey down the funnel

After the dirty water has flowed into the drain, it enters the sewer system. First, to the brownie: there, in the collectors, the drains of different apartments are connected. Then the flow of sewage is enlarged, passes through a whole bunch of sewers, combining flows from different houses, microdistricts.

Along the way, rivers of household wastewater flowing in main sewer pipes under sidewalks and roads are replenished with industrial wastewater, as well as rain and melt water flowing into storm sewers. In the end, everything ends up in the sewer pools, divided by districts. And then - to treatment facilities, depending on the size of the settlement - district or city. For example, the wastewater treatment system of St. Petersburg Vodokanal treats more than 2.1 billion m³ of wastewater daily at 3 treatment plants.

This is how the sewerage system of any settlement is arranged. The main element in it is the sewage treatment plant. because diverting waste is half the battle, it is important to purify polluted waters to the degree of safe return to natural water basins.

Anyone who drinks water has a vested interest that it be clean and safe - free of dangerous chemicals and pathogens. The owner of the cottage must be aware that the quality of the water that his child pours into a glass from the tap in the kitchen depends on how he cleans what has flowed into the toilet.

How is wastewater treated

The city sewer network differs from the local sewerage of a private house only in its size. Local sewerage of a country house too should be equipped with treatment facilities. Let's take a look at how wastewater is treated.

In most cases, the process is based on the classical scheme, consisting of two stages:

• mechanical cleaning;
• biological treatment.

In some cases (for example, if the treated wastewater needs to be discharged directly into a reservoir), a physicochemical method is also used, as well as water disinfection.

mechanical cleaning

The first stage of cleaning is mechanical. At this stage, with the help of conventional mechanical filters - gratings with different cells - garbage insoluble in water is caught: pebbles, broken glass, plastic parts from hairpins or toys, ring earrings - in general, everything that, through negligence, got into the drain of the sink or toilet.

Grease traps also belong to mechanical cleaning systems - fat traps, which, although organic, is very poorly processed by bacteria or not processed at all. If there are not too many effluents, then the mechanical treatment step is usually neglected.

Biological treatment

The biological method of wastewater treatment was developed in 1913 in England. It is based on the vital activity of a whole army of microorganisms - various amoebas, ciliates, rotifers, zoogles and others. All this company makes up the so-called activated sludge in the treatment plant.

What sewage is made of serves as food for these microorganisms. With the help of enzymes in their cells, they decompose organic substances, of which, in the main, household wastewater consists.

Biological processes of oxidation of organic matter in wastewater treatment plants can take place with the participation of aerobic forms of bacteria those who need oxygen to breathe, and anaerobic- do not need oxygen for their life. Aerobic bacteria decompose the organic matter of wastewater into carbon dioxide (CO2) and water, and ammonium nitrogen and sulfates into the simplest substances, nitrogen and phosphorus. If there is no access to oxygen, then a community of anaerobic microorganisms develops, and biochemical processes proceed with the release of methane (CH4). All this biochemistry leads to the release of energy, which is used by bacteria for their existence and reproduction.

Similar processes involving the same microorganism company in nature go on continuously- aerobic microorganisms live in the upper layers of the soil and in water bodies, anaerobic bacteria live in the lower soil layers. The vital activity of plants is inextricably linked with the life of microorganisms found in the soil and natural reservoirs; thanks to them, humus is formed and. Therefore, the purification method is called biological.

What is a septic tank and how does it differ from a metatank or aeration tank

In nature, the decomposition of organic matter proceeds independently. But when there are too many organic compounds (as in sewage), natural mechanisms cannot cope. In artificial wastewater treatment plants, the processes are more active due to specially created conditions. Both aerobic and anaerobic bacteria are used in the wastewater treatment process. But since, by definition, they cannot exist together - they have a different "worldview", - for different types of microorganisms, cleaning devices of different designs are used:

• anaerobic facilities;
• aeration treatment facilities.

Anaerobic treatment devices

Devices in which biochemical reactions occur with the participation of anaerobic bacteria include septic tank. This is an element of treatment facilities, which is a sealed container made of plastics, concrete or metal. In the septic tank, the primary treatment of wastewater takes place, their settling: what has a density greater than that of water precipitates at the bottom, lighter contaminants float on top, forming a crust.

Depending on the design, its internal volume can be divided by partitions into 3 sections. After the effluents pass their way through the vent pipe, they enter the first chamber, where the settling process begins. The chamber is gradually filled with sewage, activated sludge and insoluble debris accumulate at the bottom, a crust forms on top, and the liquid flows into the next section, where the processes continue. Thus, in the first part of the septic tank, the largest particles of pollution fall out, closer to the exit, the activated sludge layer decreases, and the drains become more and more clarified.

At the outlet of the septic tank, wastewater pollution is about 65% of original. Effluent with such a degree of pollution is sent to the soil aftertreatment - in the fields of filtration, irrigation, biological ponds, filter wells or cassettes - depending on the specific design of the treatment plant.

In this way, metatank - this is a septic tank: the processes in it go with the release of methane, which is discharged into the atmosphere through ventilation. In an artificial treatment plant of this type, natural conditions are simulated that occur at a depth underground or in swamps.

Aeration treatment facilities

If the activity of aerobic forms of microorganisms is used for wastewater treatment, then a constant supply of oxygen is required for their life.

Aeration treatment facilities. Photo from novostroi.spb.ru

Aerotanks- more sophisticated devices require a permanent connection to electricity for compressor operation. This means that they are more expensive and capricious in operation. Aeration treatment plants are used if the volume of wastewater is large or a higher degree of water purification is required, for example, to discharge clarified wastewater into a reservoir - sanitary requirements are more stringent in this case. In aerotanks for bacteria, conditions similar to natural reservoirs are created.

Filtration fields and other methods of wastewater treatment

After the polluted waste water has passed the septic tank, it enters the post-treatment. These processes may already take place in soil or water conditions, but this does not mean that clarified water from a septic tank can simply be drained into a gutter: such actions are prohibited by sanitary standards. If a violation is discovered (for example, neighbors complain or a planned inspection comes), the guilty person will be fined.

Clarified water from the septic tank is sent to specially organized areas- filtration fields, filtration wells, aeration fields, irrigation fields, biological ponds. All these types of soil treatment methods work according to a general principle, and the choice of one or another option depends on the amount of effluent and soil conditions.

The principle of treatment of wastewater that has undergone preliminary treatment is based on using the same microorganisms, only now they are in the soil. What is the difference between soil cleaning methods?

Filter fields

Filtration fields are plots of land onto which effluents from sewage treatment tanks are poured. The main requirement is a good moisture-absorbing capacity of the soil. The most suitable - sandy or sandy loam. The area of ​​the filtration field depends on the volume of runoff and soil properties. If possible, the filter fields do open- that is, effluents are poured directly onto the surface of the earth.

It is difficult to make open filtration fields in private properties, because there are not enough areas to comply with the sanitary zone - the filtration field, frankly, smells. That's why they do private filtering fields: they open the ground, arrange specially filled areas of gravel and sand. Drainage pipes are laid on a gravel-sand cushion. The supply pipes - coming from the septic tank - are located in the upper horizon of the field.

If the rate of soil absorption is insufficient, another system of drains is arranged (these are discharge drainage pipes), into which filtered water is collected. They are placed on the bottom layer. After that, the water becomes sufficiently purified and can be drained into a ditch or directly into a reservoir. The figure below shows a schematic diagram of the backfilling of the layers of the filtration field.

Important point- depth of occurrence. On the one hand, the entire structure of the drainage pipes must be placed below freezing depth if you plan to use the sewer in the winter season. And on the other hand - at least 250 mm above the highest water table.

Filter well

A filtering well is a type of filtering field. Below the freezing depth, but above the groundwater level, a well without a bottom is arranged with holes along the entire surface of the walls. Soil cleaning occurs over the entire surface of the walls of the well. A sufficient layer of gravel and sand is made around and under the bottom of the well. The number of wells depends on the filtering capacity of the soil and the amount of drains.

Another variant - filter trench. Instead of several vertically standing wells, one horizontal drainage pipe of large diameter is used.

Irrigation fields

Irrigation fields - almost the same as an open filtration field, but on a plot of land intended for draining wastewater clarified in the sewage treatment system, plants are grown. The method is good - in clarified wastewater there is a large amount of nutrients converted by bacteria in a septic tank into a form convenient for plants. Minus such a system - the inability to use in cold weather.

biological ponds

Biological ponds - reservoirs into which clarified waters are discharged from treatment facilities, water analogue of open filtration fields and irrigation fields. To prevent the ponds from blooming (a large amount of phosphorus and nitrogen in the drains provokes the active development of blue-green algae), special aquatic plants are cultivated in them that absorb excess nitrogen and phosphorus. That is why the standards for wastewater treatment for discharge into natural water bodies are much more stringent than for discharge onto the soil or into the soil. This cleaning system has the same problem as irrigation fields: the harsh climate in our country.

To prevent the ponds from blooming, special aquatic plants are cultivated in them that absorb excess nitrogen and phosphorus.

Filter cassettes

In order to prevent undertreated effluents from entering the water horizons of the soil, it is necessary to take into account the depth of treatment and the level of groundwater. If the groundwater level is high, and the soils are heavy, clayey, it is impossible to arrange a deep filtration field. The only way is to make a surface filtration field, and to avoid problems with odors and freezing in winter, build embankments above the drainage pipes. Filter cassettes can be prefabricated or assembled from drain pipes on site. The height of the embankment is determined in such a way as to exclude freezing in the winter.

Biological filters

If there is no place on the site for the device of the filtration field or you don’t want to dig half the garden for laying drains, you can install a biological filter after the septic tank - artificial filtration field, due to its device having a compact size.

Why we abandoned the local sewage system using a septic tank

, we refused a septic tank or another option for local sewerage. Why?

• financial question

To do everything right, taking into account sanitary standards, a decent amount of money is required. Even if you try to save money by using three concrete rings, eurocubes or other containers instead of a ready-made septic tank, the amount of earthwork for arranging filtration fields is enormous. Especially considering the peculiarities of the soil in our area - clay at the depth of a spade bayonet and the groundwater level half a meter from the surface.

Lyrical digression: why the option “just a septic tank and not bother with filtration fields” is not suitable? Feedback from users like: "They made a septic tank with a drain into a ditch, it has been working for 3 years, there is no smell, the neighbors do not complain, but the amenities in the house" - in my opinion, are untenable. Swamps in nature do not appear suddenly, it is a long process for which 3 years is not a period. You can, of course, argue according to the principle: enough for my life, and after me - even a flood. But the drains get into the soil of my site, and the well with drinking water is also located here.

• high groundwater level

This means that we are doomed to the construction of ground structures for soil filtration: we need to fill a hill with an area of ​​at least 30 meters and a height of almost 2 m. And the water itself will not flow up - the septic tank is in the ground, which means that we need a pumping station . And this is more money and a constant dependence on electricity.

• water supply

What do you think, what does most of the water in an ordinary apartment go to? Until I calculated it, I thought that most of the water is poured out in the shower. It turned out not: up to 45% of the total daily water consumption per person in a city apartment falls on the toilet.

Up to 45% of the total daily water consumption per person in a city apartment falls on the toilet

There is a lot of water in our area: a well can be dug almost without looking, anywhere. But the debit of such a well is small, and in summer it decreases even more. It turns out that if we want to install a flush toilet, we need to spend another N-th amount of money on the extraction of water, half of which is literally flushed into the toilet, so that later we can arrange complex and expensive structures for cleaning it.

• septic needs to be cleaned

Regularly - depending on the volume - remove the accumulated sludge in the sump. If not removed, it will eventually fill the septic tank. And if removed irregularly, the degree of wastewater treatment will decrease. Up to the point that the concentration of contaminants at the outlet will be greater than at the inlet: water flowing through a silted septic tank will wash away the settled substances and become dirtier than it was. Aeration treatment plants need to be cleaned less frequently. But they also cost more.

• filtration field life

The filter field also has an expiration date - 8-10 years old. Then the gravel-sand backfill of the drainage pipes silts up and stops cleaning the drains. The only way out is to make a new filtration field, this time excavating the second half of the site. Well, or in our case - to dig a hill, replace the filtering backfill and pour the hill back.

• adequacy of the event

And it’s not even about the lack of extra money, although this fact is also important: after moving from St. Petersburg to the village, I had to change my occupation (it’s unlikely that the neighbors - grandfather Anatoly or Aunt Dusya - need the services of an interior designer), which means changing the level of income . The point is adequacy: our entire hectare and 3 acres, garden, house and outbuildings are worth well, if a fifth of the estimate for a local sewage system. Looking for additional sources of income, working hard just to be able to habitually press the flush button after using the toilet? Why, then, did we leave the city and quit a decent job - there were no problems with the sewerage, and the toilet worked properly.

All things considered, we decided that local sewerage was not suitable for us. But this does not mean that we plan to use the yard toilet in a wooden booth in the garden. We want a completely civilized toilet. They simply opted for another system for the disposal of human waste - composting toilet. I talk more about it in my post.