And today I will tell you about sewerage and water disposal in a modern metropolis. Thanks to a recent trip to the South-Western wastewater treatment plant in St. Petersburg, I and several of my companions instantly turned from simple bloggers into world-class experts in water collection and purification technologies, and now we will be happy to show and tell you how it all works!

A pipe from which a powerful stream of rating social capital flows the contents of the sewer collector

Aeration tanks YuZOS

So, let's begin. Water diluted with soap and shampoo, street dirt, industrial waste, food leftovers, as well as the results of digestion of this food (all of this ends up in the sewer system, and then in treatment plants) has a long and thorny path to go through before it returns to the water. Neva or Gulf of Finland. This path begins either in the drain grate, if this happens on the street, or in the “fan” pipe, if we are talking about apartments and offices. From not very big ones (15 cm in diameter, everyone has probably seen them at home in the bathroom or toilet) sewer pipes, water mixed with waste enters larger communal pipes. Several houses (as well as street drains in the surrounding area) are combined into a local catchment, which, in turn, are combined into sewer areas and then into sewer basins. At each stage, the diameter of the sewage pipe increases, and in tunnel collectors it already reaches 4.7 m. Through such a hefty pipe, dirty water slowly (by gravity, no pumps) reaches the aeration stations. In St. Petersburg there are three large ones that completely cover the city, and several smaller ones in remote areas such as Repino, Pushkin or Kronstadt.

Yes, about the treatment facilities themselves. Some may have a completely reasonable question - “Why purify wastewater at all? The Bay and Neva will endure everything!” In general, this is how it used to be; until 1978, the wastewater was practically not treated in any way and immediately ended up in the bay. The bay processed them at the very least, coping, however, with the increasing flow of sewage every year worse and worse. Naturally, this state of affairs could not but affect the environment. Our Scandinavian neighbors suffered the most, but the surrounding areas of St. Petersburg also experienced a negative impact. And the prospect of a dam across the Finnish made us think that the waste of a city with a population of one million, instead of happily floating in the Baltic Sea, will now hang out between Kronstadt and (then still) Leningrad. In general, the prospects of eventually choking on sewage did not make anyone happy, and the city, represented by Vodokanal, gradually began to solve the problem of wastewater treatment. It can be considered almost completely resolved only in the last year - in the fall of 2013, the main sewer collector of the northern part of the city was launched, after which the amount of treated water reached 98.4 percent.

Let's look at the example of the South-Western Treatment Plants to see how cleaning occurs. Having reached the very bottom of the collector (the bottom is located on the territory of the treatment plant), the water rises to a height of almost 20 meters using powerful pumps. This is necessary so that dirty water goes through the stages of purification under the influence of gravity, with minimal involvement of pumping equipment.

The first stage of cleaning is the grates, on which large and not so large debris remains - all sorts of rags, dirty socks, drowned kittens, lost mobile phones and other wallets with documents. Most of what is collected goes straight to the landfill, but the most interesting finds remain in a makeshift museum.

Swimming pool with sewage. Exterior view

Swimming pool with sewage. Inside view

This room has grates that catch large debris.

Behind the cloudy plastic you can see what has been assembled by the bars. Paper and labels stand out

Brought by water

And the water moves on, the next step is sand traps. The task of this stage is to collect coarse impurities and sand - everything that passed by the grates. Before release from sand traps, chemicals are added to the water to remove phosphorus. Next, the water is sent to primary settling tanks, in which suspended and floating substances are separated.

Primary settling tanks complete the first stage of purification - mechanical and partially chemical. Filtered and settled water does not contain debris and mechanical impurities, but it is still full of not the most useful organic matter, and is also home to many microorganisms. You also need to get rid of all this, and start with organics...

The structure in the foreground moves slowly along the pool

Primary settling tanks. The water in the sewer has a temperature of about 15-16 degrees, steam is actively coming from it, since the ambient temperature is lower

The biological treatment process takes place in aeration tanks - these are huge bathtubs into which water is poured, air is pumped in and “activated sludge” is launched - a cocktail of simple microorganisms designed to digest exactly those chemical compounds that need to be gotten rid of. The air pumped into the tanks is needed to increase the activity of microorganisms; under such conditions, they almost completely “digest” the contents of the bathroom in five hours. Next, the biologically purified water is sent to secondary settling tanks, where activated sludge is separated from it. The sludge is again sent to the aeration tanks (except for the excess, which is burned), and the water goes to the last stage of purification - ultraviolet treatment.

Aero tanks. "Boiling" effect due to active air injection

Control room. You can see the entire station from above

Secondary settling tank. For some reason, the water in it really attracts birds.

At the South-Western Treatment Plants, subjective control of the quality of treatment is also carried out at this stage. It looks like this: purified and disinfected water is poured into a small aquarium in which several crayfish sit. Crayfish are very fastidious creatures; they react immediately to dirt in the water. Since people have not yet learned to distinguish the emotions of crustaceans, a more objective assessment is used - a cardiogram. If suddenly several (protection against false positives) crayfish have experienced severe stress, then something is wrong with the water, and you urgently need to figure out which of the purification stages failed.

But this is an abnormal situation, and in the usual order of things, clean water is sent to the Gulf of Finland. Yes, about cleanliness. Although crayfish exist in such water, and microbes and viruses have all been removed from it, it is still not recommended to drink it . However, the water fully complies with the environmental standards of HELCOM (the Convention for the Protection of the Baltic Sea from Pollution), which in recent years has already had a positive impact on the state of the Gulf of Finland.

Ominous green light disinfects water

Cancer detector. Attached to the shell is not an ordinary rope, but a cable through which data on the animal’s condition is transmitted.

Click-clack

I’ll say a few more words about the disposal of everything that is filtered from the water. Solid waste is transported to landfill sites, but everything else is burned at a plant located on the territory of the wastewater treatment plant. Dewatered sludge from the primary settling tanks and excess activated sludge from the secondary ones are sent to the furnace. Combustion occurs at a relatively high temperature (800 degrees) to minimize harmful substances in the exhaust. It is surprising that out of the total volume of the plant premises, stoves occupy only a small part, about 10%. The remaining 90% is given to a huge system of various filters that filter out all possible and impossible harmful substances. By the way, the plant has implemented a similar subjective “quality control” system. Only the detectors are no longer crayfish, but snails. But the principle of operation is generally the same - if the content of harmful substances at the outlet of the pipe is higher than permissible, the mollusk’s body will immediately react.

Furnaces

P waste heat boiler blower valves. The purpose is not entirely clear, but how impressive they look!

Snail. There is a tube above her head from which water is dripping. And next to it is another one, with an exhaust

P.S. One of the most popular questions asked about the announcement was “What’s with the smell? It stinks, right?” I was somewhat disappointed with the smell :) The untreated contents of the sewer (in the very first photo) have practically no smell. There is, of course, a smell in the station area, but it is very mild. The strongest smell (and this is already noticeable!) is the dehydrated sludge from the primary settling tanks and the activated sludge - what goes into the stove. That’s why, by the way, they began to burn them, the landfills to which sludge had previously been dumped gave off a very unpleasant smell for the surrounding area...

Other interesting posts on the topic of industry and production.

Sewage treatment facilities OS, WWTP, BOS.

One of the main ways to protect the natural environment from pollution is to prevent the entry of untreated water and other harmful components into water bodies. Modern treatment facilities are a set of engineering and technical solutions for the consistent filtration and disinfection of contaminated wastewater for the purpose of its reuse in production or for discharge into natural reservoirs. For this purpose, a number of methods and technologies have been developed, which will be discussed below.

Read more about wastewater treatment technology

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

Wastewater differs by source of pollution: domestic, industrial and surface (originating from precipitation). Domestic wastewater is called household wastewater. They consist of contaminated water removed from showers, toilets, kitchens, canteens and hospitals. The main pollutants are physiological and household waste.

Industrial wastewater includes water masses that were formed during:

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

This type also includes water pumped out from the subsoil during mining. The main source of pollution here is industrial waste. They may contain toxic, potentially hazardous substances, as well as waste that can be recovered and used as secondary raw materials.

Surface (atmospheric) wastewater most often contains only mineral contaminants; minimal requirements are imposed on their purification. In addition, wastewater is classified based on 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 of wastewater treatment production is performed.

Main cleaning steps

At the first stage, mechanical wastewater treatment is carried out, the purpose of which is filtration from various insoluble impurities. For this purpose, special self-cleaning gratings 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 a sand trap, small particles of sand, slag and other similar mineral elements are deposited under the influence of gravity. At the same time, 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 petroleum 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 uniform supply of liquid to the next stages of processing.

After this, 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 tank 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 physicochemical stage, purification from dissolved impurities occurs. This is done using special techniques and reagents. Coagulation, filtration, and sedimentation are used here. 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 considered to be chlorine disinfection of the liquid from remaining bacterial contaminants. The diagram below shows in detail all the stages described, indicating the equipment that is used in each stage. It is important to note that treatment methods vary from plant to plant depending on the presence of certain contaminants in the wastewater.

Features and requirements for the arrangement of treatment facilities

Domestic wastewater is classified as monotonous in composition, since the concentration of pollutants depends only on the volume of water consumed by residents. They contain insoluble contaminants, emulsions, foams and suspensions, various colloidal particles, as well as other elements. The main part of them are mineral and soluble substances. To treat domestic wastewater, a basic set of treatment facilities is used, the operating principle of which is described above.

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

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

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

In other industries, the main problem is the treatment of oil and grease-containing wastewater. For such enterprises, special oil separators or grease traps are used. But water circulation systems for purifying contaminated water are considered the safest for the environment. Such local treatment complexes are installed at car washes, as well as at manufacturing plants. They allow you to organize a closed cycle of water use without discharging it into external bodies of water.

To determine the method of organizing cleaning and selecting a specific facility, special systems and methods are used (there are many enterprises, so the process must be individualized). The price of equipment and installation work is of no small importance. Only specialists can help you choose the best option for each case.

Submit your application* Get a consultation

Every Russian city has a system of special structures that are designed to treat wastewater containing a wide variety of mineral and organic compounds to a state in which they can be discharged into the environment without harming the environment. Modern treatment facilities for the city, which are developed and manufactured by the Flotenk company, are quite technically 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 the questionnaire:

KNS:

Advantages of municipal wastewater treatment plants manufactured by Flotenk

The development, production and installation of treatment facilities is one of the main specializations of the Flotenk company. Its systems, as practice shows, have many advantages over similar products produced by many other domestic and foreign companies. Among them, it is worth noting the high efficiency of urban wastewater treatment plants from Flotenk, which is due to a carefully calculated, well-thought-out and perfectly implemented design. In addition, they are characterized by increased reliability and long service life, since their main components are made of fiberglass that is durable and resistant to various types of adverse effects.

How is city wastewater treated?

The city's wastewater is treated in stages. The wastewater entering the sewage treatment plant through the sewer system first enters a unit where the mechanical impurities contained in it are separated. After this, the wastewater goes to biological treatment, during which most of the organic compounds, as well as nitrogen compounds, are removed from it. In the next, third block, wastewater is further purified, as well as disinfected either with chlorine or treated with ultraviolet radiation. Once in the last block, municipal wastewater settles and produces sediment, which is subject to further processing.

Treatment facilities, which are developed and manufactured by the Flotenk company for cities, have mechanical wastewater treatment units, in which specialized meshes with very small cells are installed to remove fairly large waste. In addition, these blocks are also equipped with sand traps. They are containers of sufficiently large volume, in which sand settles out due to a sharp decrease in the speed of wastewater flow 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 municipal wastewater is also carried out in special tanks 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 proceed faster, air is pumped into the aeration tanks using compressors.

Secondary settling tanks, into which wastewater is sent after biological treatment, are necessary in order to separate the activated sludge contained in them, which is then sent back to aeration tanks. In addition, wastewater is disinfected in these containers, which, at the end of this process, is sent to discharge points (most often these are open reservoirs).

Water disposal– a complex of technological processes, engineering structures and equipment for drainage of wastewater, storm water and melt water from populated areas, industrial facilities, agriculture and transport infrastructure.

Water disposal should be considered in two aspects - the actual removal of wastewater from the place of generation to the place of discharge and the purification of wastewater before discharge into a water body.

The history of the development of wastewater disposal in Russia is relatively young - no more than two centuries ago, with the advent of low-rise construction and dense urban development, goldsmiths appeared on the streets - professional collectors of sewage, which were transported in barrels outside the city. The Zolotarsky business was replaced by a sewer network for discharging sewage, i.e., economic and domestic wastewater into the river flowing through the city.

Water disposal into the water body was initially carried out without treatment, by the end of the 19th century. with purification in filtration fields and only in the 30s. XX century In Russia, namely in Moscow, high-tech urban sewage treatment plants are appearing. A general and strict requirement for wastewater disposal was the location of the construction of treatment facilities and, accordingly, the point of release of treated wastewater into the river - always below the city outside the dense population. In the era of intensive civil construction and urbanization of the Russian population, this construction principle began to be violated: for example, Moscow covered all its treatment plants and wastewater outlets with dense residential buildings. This is practiced in other cities of Russia.

Wastewater or urban runoff is extremely diverse in composition and sanitary-ecological hazard; they can be classified into seven groups:

From the types of wastewater considered, liquid radioactive waste is removed, which is isolated and subject to special treatment and disposal of the radioactive concentrate.

Within each group, the composition and properties of wastewater are very diverse.

Wastewater treatment methods

1. Bringing wastewater to standard indicators for the composition of pollutants is carried out at treatment facilities using various technological stages of treatment, among which the following are distinguished:
2. mechanical treatment is the primary stage of the wastewater treatment process, at which coarse pollutants (solid impurities) are removed during the processes of sedimentation, filtration or flotation. Coarse particles are removed by gratings, sieves, sand traps, grease traps, oil traps, settling tanks and other engineering structures;
3. physico-chemical treatment - during these processes, finely dispersed, dissolved inorganic and organic substances are removed from wastewater. This group includes technologies such as electrolysis and electrocoagulation, coagulation, flocculation, etc.;
4. biological treatment is based on the ability of microorganisms to use organic pollutants as a source of nutrition, leading to complete (mineralization) or partial destruction of the structure of substances, i.e., their removal. Biological wastewater treatment can be carried out in bioponds, filtration fields, aeration tanks (reservoirs with forced aeration and a high density of communities of microorganisms, protozoa, invertebrates), membrane bioreactors.

Treatment plants

In Russia, direct responsibility for the choice of treatment technology rests with operating organizations, called “vodokanals” in our country. This term is derived from two words: water supply and sewerage. Such a combination of two different industries is not typical for EU countries, the USA and Canada. Water supply is the production and supply of a product (clean drinking water); sewerage, i.e. water disposal, is the provision of sanitary, hygienic and environmental services.

Some of the largest wastewater treatment plants in the world are the wastewater treatment plants serving Moscow.

The Kuryanovsky and Lyuberetsky treatment plants are capable of discharging 3.125 and 3.0 million m3 of wastewater daily, respectively. More powerful wastewater treatment plants are found only in China and a few US cities.

Impact on water bodies

Each identified group of wastewater affects the environmental situation in the receiving water body. Local consequences of the disposal of contaminated wastewater can become an environmental and sanitary problem for large river basins and sea coasts.

The discharge of wastewater from settlements into small rivers often completely shapes the composition and flow of water in the river. For example, water flow in the river. The Desna increases from 0.92 to 1.66 m 3 /s after the discharge of wastewater from the Yuzhnobutovo treatment plant (WTP), into the river. Pekhorka - from 1.16 to 8.40 m 3 /s after the Lyubertsy WWTP, in the river. Skhodne - from 1.85 to 2.70 m 3 /s after the Zelenograd WWTP.

Wastewater quality

Treatment facilities for municipal sewerage in cities of the Russian Federation are currently, for a number of reasons, unable to fully fulfill their main function - to purify wastewater and bring it to standard levels. In the Russian Federation in 2011, the total volume of wastewater discharges amounted to 48,095 million m3, of which only 3.8% are normatively treated and 33% (15,966 million m3) are polluted (including 6.86% discharged without treatment at all) . Municipal sewerage treatment facilities account for more than 60% of wastewater discharges into water bodies, and only 13–15% of them are classified as normatively treated.

Despite the trend towards reducing the volume of polluted wastewater, this does not lead to an improvement in the quality of wastewater.

The main problems of wastewater treatment in the Russian Federation

If in the largest cities the problems of water disposal are being systematically resolved, then in medium-sized, small and most large settlements, urban sewerage treatment facilities are in a state of decline. The main reasons for the low efficiency of treatment facilities: lack of budget funds for the reconstruction and modernization of treatment facilities; non-compliance with the technological regime of their operation; inconsistency of the composition of incoming wastewater with treatment technologies;

significant physical wear and tear of existing treatment facilities.