Norms and methods of sewer water treatment. How to organize domestic wastewater treatment Sewer water treatment

Wastewater treatment is an indispensable process, as it makes sewage waste safe for people and the environment. Today, technological progress negatively affects the water resources of our planet, so every drop counts. For this reason, treatment methods have been developed that help the effluent to be reused for irrigation of land or simply replenishing the soil. In today's article, we will discuss with you the main ways to filter sewer fluid.

To begin with, let's find out what refers to the concept of wastewater? For this understanding, it is customary to take all the liquid with and without impurities, which is drained into the sewer system. Its important characteristic is the presence of pollution obtained in a certain field of application. It is worth considering that the liquid of atmospheric precipitation is also read here.

Types of pollution

Wastewater treatment involves a process that takes place with the right selection of equipment. It is worth considering that its important component is compliance with a certain type of pollution. It is for this reason that let's find out their species that may be in wastewater:

• Mineral pollution. This type includes all inorganic components, such as: salt, earth, etc.
• organic matter. This is a sewage liquid containing in its composition the remains of the world of flora and fauna. Their composition usually consists of chemical organics and polymers.
• Biological components. They are bacteria and other various microorganisms.

Attention! In most cases, a sewer drain incorporates all three components. If these are household drains, then organics will relate to minerals as 3 to 2. As for bioorganisms, their number depends on the environment.

Norms for cleaning

Any water treatment plant is required to perform a certain level of processing. It should be noted that regulated strict standards are prescribed only for the industrial sector. In addition, the ratio of each type of impurity is fixed by law. For example, iron after treatment should be present in an amount of not more than 0.1 mg per liter.

In relation to domestic plums, the requirements are more lenient. But this is no reason to relax. One of the most important rules for managing wastewater on a private property is that untreated wastewater cannot be released into the environment. For violation of this regulation, the owner of the house will be held administratively liable.

Important! To date, the state regulates only the maximum possible amount of impurities in water. At the moment, this only applies to draining into a reservoir. But remember that the test can also make these claims in relation to the withdrawal of runoff into the soil.

Wastewater Treatment Methods

Based on the variety of methods for filtering and treating wastewater, today they can be divided into types. Namely, there are two types of wastewater treatment methods:

• destructive species;
• recovery methods.

For the former, a characteristic feature is the process of dividing effluents into simple components, which can later be easily removed, for example, in the form of gas. The second types select all valuable substances from the sewage liquid in order to process them in the future.

The cleaning process - how to do it

Technological progress does not stand still, and therefore every day there are new ideas and ways to purify wastewater. After all, do not forget that this is an additional water resource. In this section, we will get acquainted with each of the types separately, but first, let's list them:

• Mechanical;
• biological;
• Physical and chemical;
• Method of disinfection;
• Thermal recycling.

Consider in detail the methods of wastewater treatment.

mechanical way

This is one of the simplest options. The process itself includes the removal from the drains of all components that do not dissolve. What are these components? First of all, these include solid particles and fat. Sewer water is passed through a sieve and a sump, which then only passes liquid with small particles.

The best option for mechanical treatment of sewage water is the membrane method. Its main feature is nothing less than the best purification process. The main thing is not to forget that this type of filtration gives a result of 70% and is the start for the biological method.

Biological cleaning process

Wastewater treatment with biological substances is carried out using the functioning of bacteria and microorganisms in the system. Their main feature is the ability to oxidize solid particles. The basis for the creation of this method was the microflora of natural water sources. Studies have proven that drains get rid of nitrogen and phosphorus, which are dangerous for the environment. Bacteria are of the following types:

• Anaerobic microorganisms that can function without air;
• Aerobic types cannot work without oxygen.

If cleaning is carried out with the help of air, that is, aerobic bacteria, then it is possible to install a biofilter or aeration tank. These designs have a high cleaning efficiency and can deal with activated sludge. With anaerobic microorganisms, a fermentation process occurs that converts organic matter into methane and carbon dioxide.

Biofilters and aerotanks with activated sludge are used for such cleaning. They are highly purified and more efficient than biofilters for wastewater treatment. In aerotanks, water is aerated and its deep biological treatment is carried out. In addition, the result is activated sludge, which is a good fertilizer. Anaerobic wastewater treatment is carried out without access to oxygen. Under the influence of anaerobic bacteria, the process of fermentation and the conversion of organic matter into methane and carbon dioxide occurs. It is worth noting that the second method is slightly cheaper.

Attention! In modern devices, two types of microorganisms are used, which can be easily used even in industrial sewers.

Physical and chemical method

These wastewater treatment methods are very effective and are based on the teachings of the sciences of chemistry and physics. These types include:

• Electrolysis is a very popular method in industrial plants. The basis of the treatment process involves breaking down the organic constituents of the water to produce inorganics.
• Coagulation is the purification of water, which is carried out when the components stick together under the action of forces. The result of the process is the formation of an aggregate.
• Precipitation of metal hydroxide flakes- this action is the result of the influence of coagulants, which cause precipitation. Educated flakes are engaged in wastewater treatment.

The physico-chemical process has a large number of advantages, for example, the removal of toxins and impurities that are not able to oxidize. It is also worth adding that this method provides a very high percentage of cleaning. This method can easily automate the dimensions of structures for filtering, which will reduce the sensitivity of the action.

Disinfection

This method is reproduced by exposure to ultraviolet rays, chlorine or ozone. Typically, the method is used to disinfect water before being discharged into a reservoir. The most effective process is considered to be with the use of rays, as it is safe. It is worth considering that their impact can have a detrimental effect on bacteria and various viral microbes.

The type of cleaning based on chlorination implies the disinfection of all microorganisms with chlorine. The main disadvantage of this mechanism is the creation of toxins and carcinogenic compounds. For this reason, you should be very careful when using this method.

Ozonation is the treatment with ozone. Everyone knows that this is a type of gas that contains three molecules of oxygen, thereby forming a powerful oxidizing agent that kills microbes. It is important to say that this method is very expensive, so it is used very rarely in everyday life. The main scope of its use is manifested in the production of industrial sectors.

Thermal disposal

Thermal treatment of sewage effluents is carried out in situations where other methods fail. The principle of operation is to spray the liquid in the combustion fuel torch. This is a very effective method, but due to its price and volume, it is found mainly in production.

Attention! Modern treatment plants perform a process in several steps, so they are often programmed to use several methods.

So, the process of purification of sewage water is a prerequisite for the operation of the wastewater disposal system. It should not be overlooked that these requirements are regulated by sanitary and legislative norms.

Most users of a modern system do not think about where the water flows from the sink or toilet. Some concern arises if a blockage has formed and the water does not want to drain. 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 washbasin 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 appears 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 effluent that has been treated must be discharged directly into), a physico-chemical 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 ordinary 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, fell 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, they are settled: 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 the conditions of soil or a reservoir, 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 down 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 filter backfill and pour the hill back.

• adequacy of the event

And it’s not even 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.

Sewerage in any private house is one of the most important elements that can provide a fairly comfortable life. If, until recently, our grandparents, who lived in villages and villages, managed with an ordinary cesspool, where all the sewage was merged, and which spread far from the most pleasant aroma throughout the district, now people are striving to install a complete wastewater treatment system. Currently, many different systems are used for wastewater treatment, from conventional storage tanks to complex biotechnical complexes for deep water treatment.

Options for solving the issue of arranging sewerage in a private house

Wastewater treatment systems for a private house can be confidently divided into several main groups:

1. storage containers.
2. Single chamber septic tanks.
3. Multichamber septic tanks.

Storage tanks

These are sealed tanks that are installed below ground level and are equipped with an accessible exit to the surface for pumping out sewage accumulated in them. To equip such tanks, quite a few options are used, the simplest of which are ready-made containers, from metal tanks or plastic eurocubes in a protective metal mesh.

Installation of a storage tank for the sewerage of a private house

In addition, a wastewater collection tank can be made of concrete rings by installing them on a concrete pad and sealing all joints and technological openings, or casting a concrete container directly in a dug pit. Despite the simplicity of design, such tanks are not popular enough due to the need for constant pumping of sewage with solid waste.

Only sewage trucks with powerful pumps and tanks for pumped-out mud can perform such work. Such a service in some regions is quite expensive, and given that it will have to be accessed regularly, the use of sewerage becomes unprofitable. Another significant disadvantage of storage tanks for sewage is the risk of destruction of the tank and seepage of sewage into the soil, and then into groundwater, which can be used for water intake. This is especially true for metal containers, which, although they are treated with special protective compounds, inside and out, are still subject to corrosion due to the constant negative impact of the environment and chemical elements contained in detergents and entering the tank along with wastewater. It is practically impossible to check the condition and integrity of a cistern or a metal tank buried underground, since for this it must be removed from the ground.

Such structures made of concrete, although more resistant to corrosion, are still destroyed from time to time.

The exceptions are plastic tanks, which are not afraid of corrosion. If, during installation, all protective measures were taken to protect the tank from external mechanical and physical impact, the storage tank made of plastic can last forever. The problem of plastic drives in limited sizes. Although modern technologies make it possible to melt quite voluminous plastic containers in terms of strength, they are practically not inferior to their iron counterparts.

Single chamber septic tanks

This type of treatment plant is made of two types. The cheapest option is a drainage well without a bottom. To filter wastewater, sand and gravel mixture are poured into such a well at the bottom. The volume of such a septic tank is limited by the volume of the tank, which is used as a drainage well. The most common way is to build a single-chamber septic tank from concrete rings, which are mounted on top of each other in a specially dug hole. To ensure that pollution from wastewater does not go into the upper layers of the soil, where the root system of most plants is located, the joints between the rings are carefully sealed. This type of septic tank is recommended to be installed only in areas with the lowest possible groundwater horizon, otherwise, partially filtered sewage and dirt can seep through a small thickness of soil and pollute underground water sources. In addition to concrete rings for single-chamber septic tanks, metal tanks can be used, in the bottom of which large enough holes are made to drain the sewer drain.

installation of a sewer septic tank for a private house

A more acceptable version of a single-chamber septic tank, which is able not only to provide a sufficiently high-quality sewer system, but also not to pollute the environment, is a sealed tank with access to filtration fields or an infiltrator. Septic tanks of such a plan are sold in a ready-made factory version or are made independently. The design of treatment facilities with a single-chamber system is quite simple, which makes it possible to build it yourself. A sealed tank into which sewage is connected from the house can be made from any suitable material. Often these are the same concrete rings, only installed on a concrete pad to prevent wastewater from escaping into the ground. This tank serves as a sump in which solid, insoluble dirt particles settle to the bottom, while lighter fat and chemical particles, on the contrary, float to the surface.

Partially settled water from the middle layer is discharged through the overflow pipe to the filtration fields or infiltrator, which is finally cleaned and drained into the ground. The infiltrator, as well as the filtration field, is essentially the same mechanical natural filter made of sand and gravel. To ensure better filtration, such a mixture is poured over a sufficiently large area, and wastewater is distributed evenly over it. Professional factory infiltrators can be equipped with a wastewater collection system to drain them not into the ground, but into a sewage system, if any are nearby. The main disadvantage of such septic tanks is the need for periodic pumping of solid waste and activated sludge from the sump, as well as the replacement of sand and gravel as they clog and silt. Another drawback is the rather harsh conditions that allow the installation of sewers with a drain into the soil.

Multi-chamber septic tanks

Devices with several connecting tanks are quite effective for treating wastewater in a private house. To create septic tanks of this type, 2-3 sealed containers made of metal, plastic or concrete are used, connected by overflow pipes. Often, additional mechanical filters and grease traps are installed in such pipes to improve the cleaning process.

installation of a multi-chamber septic tank with a fine cleaning system

Basically, the first two chambers of septic tanks serve to settling water, but unlike single-chamber septic tanks, settling is of better quality. A so-called biological filter is installed in one of the containers. To do this, a colony of aerobic bacteria is planted in it, which are actively involved in the decomposition of the organic remains of human life. Unlike the anaerobic bacteria used in pit latrines and single chamber septic tanks, aerobic bacteria cannot thrive without a constant supply of oxygen. For this reason, the arrangement of the ventilation system is mandatory. Depending on the size of the tank and, accordingly, on the volume of wastewater, ventilation can be made with a natural inflow or with a forced oxygen injection system. The advantage of forced ventilation in a constant supply of air for bacteria that decompose organic residues, but its energy dependence is also its disadvantage. In the event of a power outage, the flow of oxygen stops, and bacteria can die.

After passing through several sedimentation chambers and treatment with bacteria, wastewater is discharged into an infiltrator or aeration fields, which are also buried in the ground. When installing a system with aeration - filtration fields, it should be remembered that planting fruit-bearing plants is not recommended above them and within a radius of several meters around. Otherwise, there is a risk that the plants absorb dirt particles through the roots and transfer them as harmful substances to fruits that a person can eat. In an infiltrator with a plastic dome, this problem does not arise, since the discharge of purified water occurs deep underground. The only limitation in this case is the planting of large trees with a developed root system that can damage the plastic.

Sewer biotreatment stations in a private house allow you to get completely purified water that can be reused for domestic needs, for example, for irrigation. These are complex devices, reminiscent of multi-chamber septic tanks in their design, but with a much more complex device that ensures their efficiency and completely autonomous principle of operation.

installation of a biological treatment plant

In addition to settling the water and separating the fatty components, which takes place in the first tank, the further discharged and partially purified water is saturated with a large volume of oxygen. This process is called liquid aeration. As a result, clarified water enters the chamber with activated biological sludge, which is saturated with aerobic bacteria, which are actively involved in the decomposition of organic matter. The last step in purification is the treatment of water with chemicals that completely kill bacteria.

Considering that overflows, oxygen saturation and forced ventilation system are controlled automatically, the cleaning station needs a constant supply of electricity. In addition, plants of this type are one of the most expensive, albeit effective, methods of wastewater treatment. This causes their low popularity among ordinary consumers. Often, biological treatment plants are installed on several houses located nearby.

There are practically no restrictions for the installation of such structures, since deep cleaning and completely sealed tanks of the device exclude accidental contamination of the soil and groundwater.

Choosing a sewer system

The selection of treatment facilities depends on a number of specific factors that are individual in each individual case:

1. Financial opportunities of the consumer. More modern septic tanks that purify water up to 85-95% are quite expensive and not always affordable for the average consumer.
2. The volume of the septic tank is determined by the minimum daily level of wastewater discharged into the sewer. The calculation of the required volume is usually done by specialists who take into account all the individual characteristics of the sewer system, but you can also independently carry out this calculation using a simple formula.

On average, from 150 to 200 liters of liquid is discharged into the sewer per person per day. These figures are averaged and include not only the direct draining of water, but also the use of washing machines, dishwashers and other household appliances. The minimum volume of a septic tank must cover at least 3 daily volumes, that is, for one permanent resident using sewerage, a septic tank volume of 600 liters is required. For two people it will be 1200 liters for three - 1800 liters and so on.

1. The type of soil, the depth of groundwater, the location of a natural reservoir nearby and the possibility of draining into common sewers, in some cases determines the possibility of installing one or another type of septic tank.
2. Availability of calling a cesspool truck. Quite often, in remote regions, there is no service for calling vacuum trucks, or it turns out to be too unprofitable financially. In such cases, it is worth thinking about arranging a septic tank with the ability to clean the sedimentation tanks in which solid waste accumulates on its own.
3. Possibility of continuous supply of electricity. Especially important for septic tanks and biological treatment plants that use aerobic bacteria, forced ventilation systems and circulation pumps.

installation of a septic tank in the ground

In general, the rules for installing a septic tank or other type of treatment plant come from a number of individual characteristics, but there are also general recommendations in this matter.

The pit where the septic tank is installed must be insulated in order to eliminate the risk of freezing of the liquid in the tanks in winter, when the temperature drops low enough. In a number of regions, it is also recommended to insulate sewer pipes leading out of the house to sewage treatment plants. Considering that the sewer works on the basis of gravity, the installation of a septic tank must be carried out so that the sewer pipes are at an angle of at least 2-3 degrees with an inclination from the house to the septic tank.

When installing sufficiently large treatment facilities, a pit for them is dug no closer than 3-5 meters from capital buildings. Otherwise, there is a risk of subsidence of the foundation of the house. Also, sufficient removal will ensure that there is no smell in the residential area, even if the septic tank fails and begins to smell unpleasant.

And of course, you should ensure that wastewater from drainage wells or infiltrators does not pollute the environment. To do this, it is not recommended to install treatment plants closer than 30-50 meters from wells for drinking water intake.

According to environmental standards, a local sewer system must be installed in each suburban area, which cleans and recycles domestic wastewater. Domestic wastewater treatment can be carried out by small devices or a whole range of different devices. How to build a sewage treatment plant yourself, read on.

Existing methods of wastewater treatment

Currently, domestic wastewater treatment is carried out in the following ways:

• mechanical. This method consists in cleaning wastewater from large particles: sand, grease, and so on. For mechanical cleaning, structures such as a conventional grate or sieve, a sand trap, a sump are used;

• biological. This method is based on the work of microorganisms (from which it got its name), which feed on various types of pollution. As a result of biological treatment, impurities contained in wastewater decompose into water and gas, which is discharged through a special pipe.

Biological treatment can be carried out using:

• biofilter, which is installed in a septic tank, prefabricated or filtering well. Cleaning is done by anaerobic bacteria;

• air filter. In this cleaning element, cleaning is carried out with the help of aerobic bacteria, which require air access to work.

In industrial wastewater treatment plants, cleaning methods such as physical-chemical or chemical can be used, which are based on the interaction of contaminants with special substances.

How to make a sewage treatment plant yourself

Domestic wastewater treatment plants can be purchased at specialized stores or made independently. Each system must have:

• coarse mechanical filter, which is installed before the septic tank or sump;
• biological wastewater treatment plant;
• treated water receiver.

mechanical cleaning

Mechanical treatment plants allow you to remove large particles from wastewater: sand, grease, oil films, and so on. To properly build a mechanical cleaning system, you must:

1. install a rake grate at the exit from the sewer system of the house. This will remove the largest particles from the incoming water;

1. further, the water purified from large impurities must enter the sand trap for mechanical cleaning from smaller impurities.

If there is a large amount of fat deposits in the household drains, then the system is supplemented with a grease trap.

Biological treatment

After a rough cleaning of wastewater, you can proceed to biological cleaning. To do this, the following types of devices are installed in the local treatment plant system:

• septic tank with biofilter. Inside the septic tank, depending on the size and cost of the device, there are several cameras. The first and second chambers are used as settling tanks, in which particles that are not caught during mechanical cleaning settle. The third chamber is equipped with a biofilter. The biofilter itself may consist of slag, gravel, crushed stone and other similar materials. When water passes through a biofilter, wastewater is cleaned by approximately 90%;

• aeration tank or metatank. In completely sealed devices, the final treatment of wastewater is carried out. The aerotank can also consist of several compartments, for example, primary treatment and secondary treatment. Between the treatment compartments, there is a sump without fail.

If a single-chamber aerotank is installed in the system, then an additional sump must be installed for final cleaning.

How to properly install the treatment facilities provided for by the scheme, see the video.

Receiver

Where to organize the discharge of domestic wastewater after treatment? Purified water can be:

• reuse, but exclusively for household needs: washing paths, cars, windows, floors, and so on, as well as for watering plants. For this purpose, water from the treatment facilities must fall into a special receiver (prefabricated well, barrel, and so on);
• dump into sewers and natural reservoirs located near the summer cottage;
• let into the ground.

If it is not intended to reuse water, and there are no reservoirs nearby, then you can build:

• filter well;

The filter well is a small container without a bottom. For its arrangement you need:

• concrete rings, plastic frame or brick. From these materials, the well itself is constructed as a receiving container;
• gravel, crushed stone, sand. Materials are required so that the waters undergo additional purification, do not harm the plants on the site;
• pipes for connecting the device with;
• a cover to give the well an aesthetic appearance, as well as placed for safety purposes.

According to the rules of environmental safety, the filter well is installed at a distance of: 10 m from a residential building, 25 m from a drinking well and 5 m - 7 m from cultural plantations.

For faster filtration of treated effluents, a filtration field can be built. A significant disadvantage of such a structure is its large size, which allows it to be used in areas with a sufficient amount of free space.

To build a filtration field, you will need:

• sand or gravel, which are used as an additional element of the cleaning system;
• pipes with holes laid over the entire area of ​​\u200b\u200bthe site and constituting the drainage network;
• covering material, such as geotextiles.

Thus, the local cleaning system is developed by the user independently or with the help of specialists. Each system must have mechanical and biological cleaning agents selected by the user. When choosing devices for cleaning, it is necessary to be guided not only by the type of equipment and the functions performed, but also by the size based on the daily consumption of oxen by all those living in the house.

The sewerage device in the absence of a centralized system is a complex engineering task. The sewerage scheme is determined by the type of toilet equipment, the total volume of "gray" wastewater from washbasins, bathtubs, washing machines, and pools. As well as the geological features of the area: the depth of groundwater, the filtering capacity of the soil, the presence of water intakes in the immediate vicinity of the treatment facilities.

Wastewater entering the sewer network may contain waste of mineral origin (sand, clay, slag particles, salts, acids, alkalis dissolved in water); rotting organic matter (of animal and vegetable origin); pathogenic bacteria, harmful chemicals. Wastewater treatment methods used in local sewage systems can be divided into three main types: mechanical, chemical and biological.

Chemical cleaning method wastewater is based on the use of various reagents that convert dissolved impurities into a sparingly soluble state. Further, the precipitation of these substances occurs. This method is mainly used for industrial wastewater treatment.

mechanical cleaning It consists in removing from the waste liquid waste of mineral origin, which are in it in an undissolved, and partially in suspension state, as well as from foreign objects floating in wastewater. When using a mechanical cleaning method, sedimentation and filtration of wastewater occurs. One of the disadvantages of this method is that there is no water purification from dissolved organic contaminants. Therefore, mechanical treatment facilities (settlers, sand traps, grates and sieves) are most often a preliminary step before biological treatment.

AT biological treatment Wastewater involves bacteria, which, depending on their relationship to oxygen, are divided into two groups: aerobes (using oxygen dissolved in water during their breathing) and anaerobes (developing in the absence of free oxygen).

Anaerobic (without air access) treatment is carried out in closed containers (methane tanks, septic tanks, two-tier settling tanks), where organic pollutants are fermented with the help of methane-forming anaerobic bacteria.

At aerobic (with air supply) cleaning wastewater use drainage fields, filtering wells, biological filters and aerotanks, in which the cleaning process takes place intensively. Oxygen, necessary for the life of microorganisms, comes from the surrounding air or it is injected with special compressors (blowers). A large amount of organic substances contained in wastewater serves as a favorable nutrient medium for aerobic bacteria, which are able to absorb various organic substances in the course of their life. During biological treatment, activated sludge is created. Sewage is mixed with activated sludge, significantly accelerating and improving the oxidation process. As a result, pathogenic microbes are absorbed by activated sludge, die or become its active agents, or they decay into harmless ones. Due to this, the water loses its tendency to rot, becomes transparent, and its bacterial contamination is reduced.

In modern biological treatment plants, both types of bacteria are used: anaerobes and aerobes. First, the sewage flow enters the tank with anaerobes and oxidizes there for 2-3 days, then it goes through the process of post-treatment in tanks with aerobes or in natural conditions. Waste liquid during biological treatment is almost completely freed from organic matter and harmful bacteria.

Rice. 24. Dry closet

For a summer house, you can choose a cheaper option: arrange for gray water to drain from sinks and showers and use a dry closet (Fig. 24). This is an intermediate option for those who do not want to install an expensive sewage system and at the same time want the “latrine” to be more convenient than the “outhouse” - backlash or powder closet.