City sewerage treatment facilities. The principle of operation of wastewater treatment plants

Convenience is an indispensable attribute of our time. A person wants comfort, wherever he is: in a city apartment or in a house, in nature, therefore, one cannot do without a treatment plant.

Decentralized sewage treatment plants are of two main types of treatment: mechanical and biological. In the first type, the sewage drains and their clarified ones are settled. The second is more complex and expensive, but it guarantees the maximum degree of wastewater treatment - this is biological treatment.

If we talk about the device of an individual sewerage system, then there are three options: a sump, a septic tank and deep biological treatment plants.

The basis of the simplest sewage system is a storage tank - a sump. Everything here is elementary: wastewater from all sources (bathroom (shower), toilet, sink) enters the tank. As the sump fills, it is pumped out with the help of special equipment. In this case, it is not necessary to talk about at least some elementary purification technology.

But you should not discount the drives, because they also have advantages: low cost, absolute environmental friendliness, since the container is sealed - then nothing gets into the ground at all, and the possibility of installation even in the smallest area. There is only one minus: you have to regularly call a sewage truck, but for a summer house or a house where no one lives permanently, this is ideal. It is unlikely that you will need to pump out the sewer more than once a year.

Septic tanks

A septic tank-based sewage treatment plant is a fairly popular sewer system. Its cost can be both minimal and quite impressive. It all depends on the choice of septic tank. If you take a single-chamber mini installation and mount it together with a filtration well, you will get the cheapest scheme that even pensioners can afford.

But when arranging a treatment system, the most important thing is safety! Even domestic wastewater is the object of environmental pollution and can threaten the ecological safety of the site. In no case, in order to save money, you should not install a system that can harm the health of your family members.

Volume and performance

What affects the safety of use? First of all, the capacity of the septic tank should not be small. Calculating the required volume of a septic tank is simple: according to the standards, one person spends 200 liters of water per day, respectively, he produces so much hard water. SNiP 2.04.03-85 states that the estimated volume of a septic tank should include at least three times the daily inflow of sewage, taking into account that the system serves no more than 25 people.

This means that we multiply the number of residents by 200, and then multiply by three, add at least 15% of the value obtained (a reserve in case they come to visit, or the whole family gathers at home and there is a high risk of a volley discharge from all sources: soul, toilet bowl, sinks) and here is the end result - the volume you need. When a family likes to wash and wash clothes often, and on weekends a hospitable house receives guests, a septic tank capacity reserve of 25% should be provided.

Another important indicator characterizing the efficiency of the septic tank and, accordingly, the quality of wastewater treatment is productivity. Even models that are in the same price category and have the same volume may have different performance, even if it does not differ much, but, nevertheless, consider this fact.

Number of cameras

The number of cameras in a septic tank is directly proportional to its cost: a single-chamber one is cheaper than a two-chamber or three-chamber one. If we talk about the justification for using a multi-chamber septic tank, then everything is not so simple. A small family with minimal water consumption, having a plot with sandy soil, is quite enough with a single-chamber septic tank. When the family is large, a lot of water is consumed, the soil on the site is not very permeable, then it is better to opt for at least a two-chamber installation.

By the way, even a three-chamber septic tank purifies sewage by a maximum of 70%, and in general, the degree of wastewater treatment by a septic tank is 50-60%. The principle of operation of such treatment facilities is that when sewage flows into a septic tank, if it has several chambers, then into the first chamber, they are stratified and settled.

A sediment falls to the bottom, and a liquid with a small amount of impurities remains on top, it overflows into the second chamber, where most of the already light particles settle to the bottom (the same thing happens in the third chamber, if any), and the clarified liquid is drained to the ground through filtration fields, infiltrators or drainage wells. In all chambers, the process of fermentation and decomposition of organic sediment takes place.

Filtering Required

Filtration is required to treat wastewater leaving the septic tank. It occurs either in filtration fields, which are arranged in the ground using perforated pipes, or in a drainage well. The most modern technology is the use of an additional element in the sewage system - an infiltrator.

Industrial designs are made of plastic, they have the shape of an inverted trough. The use of this device allows even a volley discharge into the sewer without the risk of polluting the environment with wastewater.

Infiltrator

The infiltrator is not expensive, and experts recommend using it for wastewater treatment plants instead of filtration fields that require a significant area. But when choosing a product, pay attention to its design: it is better if it has perforated walls, then you can count on maximum performance.

The infiltrator protects the upper layers of the soil from the ingress of incompletely treated wastewater into them. Before installing it, a layer of fine-grained gravel is poured into the pit (prefer granite - or from other hard rocks, and not made from construction or metallurgical waste).

Crushed stone will work as a filter, catching organic impurities remaining in them from incoming effluents. And if the device is not only placed on a gravel cushion, but also covered with gravel on the sides, then the filtration area will increase significantly.

Do you need agricultural fabric?

Another important point: the use of non-woven material when installing a treatment plant. A lot of so-called "specialists" lay it in a layer of rubble under the infiltrator. This is completely unacceptable! This material does not carry any functional load in this place, in addition, its presence will contribute to the gradual silting of the filtration layer.

In other words, the fabric will significantly impair the throughput of the drainage layer, and over time, the filtration process will become impossible. The only and very important purpose of agrofabric is to filter sand, which during rains can fall into the lower layers of the soil and settle in crushed stone, worsening its throughput. Therefore, it is necessary to place the tissue on top of the installed infiltrator.

Septic tank with biofilter

Now septic tanks have appeared that can work without additional wastewater treatment, in any case, manufacturers say this, but in practice a drainage ditch is still required, it is into it that the processed liquid will be discharged. These are septic tanks with biofilters.

A septic tank with a built-in biofilter is usually three-chamber (but always horizontal). The first chamber is a wastewater receiver, here they have their first sediment, in the second chamber they settle again, and already clarified liquid enters the third compartment. The third chamber is the largest biofilter, as it contains the filtration material.

Most often, it is expanded clay, but granular polymers are also used, voluminous plastic nets or brushes are used. They are needed so that microorganisms can settle on them, which will process the remains of organic matter from wastewater. A biofilter is a filtration field in miniature. The regulatory framework for the use of biofilters is set out in SNiP 2.04.03-85 (Facilities for biological wastewater treatment).

Advantages and disadvantages

Biofilters are either built into the septic tank or stand-alone. According to the principle of work: aerobic and anaerobic. In some, cleaning occurs with the help of microorganisms formed when air is available (a ventilation system is required), while in others there is no air access (sealed installations), so anaerobic bacteria settle there.

Advantages of biofilters:

• compactness;
• energy independence;
• ease of installation and operation;
• wastewater treatment up to 90-95% (when using a filter of the required capacity).

But these treatment facilities also have some disadvantages:

• high price;
• do not pour cleaning and detergents based on chlorine, any paints, solvents, medicines into the sewer;
• regularly need to add concentrated preparations with strains of different bacteria;
• biofilters are not used in houses with seasonal residence - in wastewater, the biological process must go on constantly, and if there are no drains and there is nothing for the microflora to process, it dies.

Recommendations in each case may be different. Knowing certain nuances of the biofilter, consult with experts about the validity of its use with your treatment plant.

Deep Cleaning Stations

And the last treatment facilities are stations for deep biological treatment. So far, these are the most modern installations. In them, all processes are more intensive and the quality of cleaning is higher - up to 98%. Waste water from the system can be drained directly into the ground or into a ditch - it will not cause any harm to the environment. Despite their effectiveness, the stations themselves are modest in size and can be installed on any soil and even with a high level of groundwater.

A high degree of wastewater treatment in these systems is achieved through a phased aerobic and anaerobic methods. The compact housing contains: four chambers (reception, aeration tank, secondary clarifier and activated sludge stabilization section), a compressor and an automatic control system.

Principle of operation

In the receiving compartment, wastewater is stratified: heavy fractions precipitate, and the primary purification process begins.

Then, with the help of a pump, the liquid is pumped into the second chamber (aerotank), where the compressor pumps air to activate the activity of microorganisms, so that the process of splitting organic compounds goes much faster. Lighter particles that float in the wastewater overflow back into the first chamber.

After the aeration tank, purified water mixed with activated sludge enters the secondary settling tank, where the sludge settles and returns to the second chamber, from where it is pumped to the sludge stabilization section, and clean water is discharged outside the installation. The accumulated sludge is also periodically pumped out, and this can be done using the supplied pump. Silt is an excellent fertilizer, and it can be used to feed plants in the garden, because it does not have an unpleasant odor.

The advantages of this system are many. Among them, of course, are the high quality of wastewater treatment, the compactness and durability of the plant, which operates completely autonomously without human intervention, but needs periodic maintenance. But the limiting factors for the use of this system are: high price and energy dependence.

Make the right choice!

Treatment facilities of any version have the right to exist in each specific case. To make the right choice, you need to compare a lot of factors, and since even the simplest sewer system will cost a couple of tens of thousands of rubles, and more advanced and productive ones will cost much more, a mistake in choosing will cost a very tidy sum.

With all your questions and doubts, contact highly qualified specialists who will recommend you a wastewater treatment system, and subsequently install it. The employees of our company Moskomplekt LLC have extensive experience in installing treatment facilities of varying complexity, and we are ready to advise you on this complex topic. Call, leave requests for installation! We work quickly, efficiently and not expensive, but with a guarantee!

Sewer treatment facilities OS, KOS, BOS.

One of the main ways to protect the natural environment from pollution is to prevent the ingress of untreated water and other harmful components into water bodies. Modern treatment facilities are a set of engineering and technical solutions for sequential filtration and disinfection of polluted effluents with a view to their reuse in production or for discharge into natural water bodies. For this, a number of methods and technologies have been developed, which will be discussed below.

More about wastewater treatment technology

Since centralized sewerage systems are not laid in all places, and some industrial enterprises require preliminary preparation of wastewater, today local sewer facilities are very often equipped. They are also in demand in private houses, suburban cottage towns and detached residential complexes, industrial enterprises, workshops.

Wastewater differs in the source of pollution: household, industrial and surface (occurring from atmospheric precipitation). Household drains are called household fecal. They consist of contaminated water removed from showers, toilets, kitchens, canteens and hospitals. The main pollutants are physiological and household waste.

Industrial effluents include water masses that were formed during:

• performance of various production and technological operations;
• washing of raw materials and finished products;
• equipment cooling.

This variety also includes water pumped out of the bowels during the extraction of minerals. Industrial waste is the main source of pollution here. They may contain toxic, potentially hazardous substances, as well as waste that can be recovered and used as secondary raw materials.

Surface (atmospheric) effluents most often contain only mineral contaminants, minimal requirements are imposed on their purification. In addition, wastewater is classified according to the concentration of various pollutants. These characteristics influence the choice of method and number of purification steps. To determine the composition of the equipment, the need for construction, as well as the capacity of various types of structures, a calculation is made of the production of wastewater treatment.

Basic cleaning steps

At the first stage, mechanical wastewater treatment is performed, the purpose of which is filtration from various insoluble impurities. For this, special self-cleaning grids and sieves are used. The retained waste, together with other sludge, is sent for further processing or taken to landfills along with municipal solid waste.

In the sand trap, fine particles of sand, slag and other similar mineral elements are deposited under the influence of gravity. In this case, the filtered composition is suitable for further use after processing. The remaining undissolved substances are reliably retained in special settling tanks and septic tanks, and fats and oil products are extracted using grease traps, oil traps and flotators. At the mechanical treatment stage, up to three quarters of mineral contaminants are removed from waste streams. This ensures the uniformity of the liquid supply to the next stages of processing.

After that, biological cleaning methods are used, performed with the help of microorganisms and protozoa. The first structure where water enters at the biological stage is special primary settling tanks, in which suspended organic matter settles. At the same time, another type of settling tanks is used, in which activated sludge is removed from the bottom. Biological treatment allows you to remove more than 90% of organic contaminants.

At the physico-chemical stage, the dissolved impurities are removed. This is done using special techniques and reagents. It uses coagulation, filtration, and settling. Along with them, various additional processing technologies are used, including: hyperfiltration, sorption, ion exchange, removal of nitrogen-containing substances and phosphates.

The last stage of treatment is chlorine disinfection of the liquid from the remaining bacterial contaminants. The diagram below shows in detail all the stages described, indicating the equipment used in each stage. It is important to note that treatment methods for various industrial enterprises differ depending on the presence of certain pollutants in wastewater.

Features and requirements for the arrangement of treatment facilities

Domestic sewage is classified as monotonous in composition, since the concentration of pollutants depends only on the volume of water consumed by residents. They contain insoluble impurities, emulsions, foams and suspensions, various colloidal particles, and other elements. Their main part is mineral and soluble substances. For the treatment of domestic wastewater, a basic set of treatment facilities is used, the principle of operation of which is described above.

In general, domestic sewers are considered simpler, since they are built to treat wastewater from one or more private houses and outbuildings. They do not require relatively high performance. For this purpose, specially designed installations are used that provide biological wastewater treatment.

Thanks to them, in suburban housing it became possible not only to equip a shower room, bathroom or toilet, but also to connect various household appliances. Typically, such installations are easy to install and operate, do not require additional components.

For industrial effluents, the composition and degree of pollution vary depending on the nature of the production, as well as options for using water to provide the technological process. In the production of food products, wastewater is characterized by high pollution with organic substances, therefore, biological treatment is considered the main method of treating such water. The best option can be called the use of an aerobic and anaerobic method or a combination of both.

In other industries, the main problem is the treatment of oil and fat-containing effluents. For such enterprises, special oil separators or grease traps are used. But the most safe for the environment are water-circulation systems for the purification of polluted water. Such local treatment complexes are installed at car washes, as well as at manufacturing enterprises. They allow you to organize a closed cycle of water use without its discharge into external water bodies.

Special systems and methods are used to determine the method of organizing cleaning and choosing a specific facility (there are many enterprises, so the process must be individualized). Equally important is the price of equipment and work on its installation. Only experts will help you choose the best option for each case.

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Depending on the wastewater entering the sewer network, city sewers are divided into common and separate.

In the first case, melt and rainwater enters the sewerage system along with domestic wastewater. With separate sewerage, melt and rainwater is directed through separately laid drains (storm drains) without treatment into open water bodies (ponds, rivers, lakes, etc.).

A separate type of sewerage is the most common method that requires less labor and material costs. Wastewater from city buildings is directed to yard lines and then to city sewer pipes that are connected to the city sewer. For the movement of drains, pipes are laid with a slope and gradual penetration into the ground. If the level of burial exceeds the level of a reservoir or river into which wastewater is released, then a pumping station with fecal pumps is installed at the end of the collector, which pumps wastewater to the city sewerage treatment plant through a pressure collector.

City wastewater treatment methods

Treatment methods depend on the composition of the effluent, so they are very diverse. In the city sewerage system, the first stage is mechanical cleaning in sand traps, grates and settling tanks, in which contaminants that are not dissolved in wastewater are retained.

Sediments (sludge) accumulated in settling tanks rot in digesters. Rotting here is accelerated by heating and mixing the sediment. The methane gas released during decomposition is used as fuel for the needs of stations. Dehydrated, decayed and dried sludge is used as fertilizer.

The next stage of wastewater treatment is biological treatment - with the help of microorganisms that feed in the presence of oxygen on organic contaminants contained in wastewater.

There are 2 types of biological treatment:

* natural. In this case, the runoff is passed through the soil specially prepared for this purpose - in the fields of irrigation or filtration;

* artificial treatment facilities for urban sewerage in aerotanks - special tanks in which effluents and activated sludge added to them are blown with air coming from an aeration station (compressors). The next stage of artificial treatment is secondary settling tanks, in which activated sludge is released, which is directed further to aerotanks. The effluents treated here are further disinfected by electrolysis, or with the help of gaseous (liquid) chlorine, and enter open water bodies.

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 sludge 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 wastewater, 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 settling tanks, to which wastewater is directed 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).