Modern ecology, alas, leaves much to be desired - all pollution of biological, chemical, mechanical, organic origin sooner or later penetrates the soil and water bodies. The supply of “healthy” clean water is becoming smaller every year, in which the constant use of household chemicals and the active development of production play a certain role. The wastewater contains a huge amount of toxic impurities, the removal of which must be complex and multi-level.
Different methods are used for water purification - the optimal choice is made taking into account the type of contaminants, desired results, and available capabilities.
The simplest option is . It is aimed at removing insoluble components that pollute water - these are fats and solid inclusions. First, the wastewater passes through grates, then sieves and ends up in settling tanks. Small components are deposited in sand traps, petroleum products are deposited in gasoline and oil traps, and in grease traps.
A more advanced cleaning method is membrane. It guarantees the most precise removal of contaminants. involves the use of appropriate organisms that oxidize organic inclusions. The basis of the technique is the natural purification of reservoirs and rivers at the expense of their population with beneficial microflora that removes phosphorus, nitrogen and other unnecessary impurities. The biological cleaning method can be anaerobic or aerobic. Aerobic requires bacteria, the life of which is impossible without oxygen - biofilters and aeration tanks filled with activated sludge are installed. The degree of purification and efficiency is higher than for a biofilter for wastewater treatment. Anaerobic purification does not require access to oxygen.
It involves the use of electrolysis, coagulation, as well as the precipitation of phosphorus with metal salts. Disinfection is carried out by ultraviolet irradiation, chlorine treatment, and ozonation. Disinfection with ultraviolet irradiation is a much safer and more effective method than chlorination, since it is carried out without the formation of toxic substances. UV radiation is harmful to all organisms, therefore it destroys all dangerous pathogens. Chlorination is based on the ability of active chlorine to act on microorganisms and destroy them. A significant drawback of the method is the formation of chlorine-containing toxins, carcinogenic substances.
Ozonation involves the disinfection of wastewater with ozone. Ozone is a gas with a triatomic molecular structure, a strong oxidizing agent that kills bacteria. The technique is expensive and is used to release ketones and aldehydes.
Thermal recovery is optimal for treating process wastewater when other methods are not effective. At modern treatment complexes, wastewater undergoes multi-component step-by-step treatment.
Primary mechanical treatment is always recommended, followed by biological treatment, additional treatment and disinfection of wastewater. 
Wastewater is water masses contaminated with industrial waste, for the removal of which from the areas of settlements and industrial enterprises appropriate sewer systems are used. Runoff also includes water formed as a result of precipitation. Organic inclusions begin to rot en masse, which causes deterioration in the condition of water bodies and air, and leads to the massive spread of bacterial flora. For this reason, important tasks of water treatment are the organization of drainage, wastewater treatment, and the prevention of active harm to the environment and human health.
The level of wastewater pollution must be calculated taking into account the concentration of impurities, expressed as mass per unit volume (g/m3 or mg/l). Domestic wastewater is a uniform formula in terms of composition; the concentration of pollutants depends on the volume of water mass consumed, as well as consumption standards.
Degrees and types of pollution of domestic wastewater:
Pollutants are also divided into organic, mineral, and biological. Mineral - these are slags, clay, sand, salts, alkalis, acids, etc. Organic - plant or animal, namely the remains of plants, vegetables, fruits, vegetable oils, paper, feces, tissue particles, gluten. Biological impurities – microorganisms, fungi, bacteria, algae.
Approximate proportions of pollutants in household wastewater:
The composition of industrial wastewater and the level of its pollution are indicators that vary depending on the nature of a particular production and the conditions for using wastewater in the technological process.
Atmospheric runoff is affected by climate, terrain, the nature of buildings, and the type of road surface.
Water treatment facilities must provide specified epidemic and radiation indicators and have a balanced chemical composition. After entering water treatment facilities, water undergoes complex biological and mechanical purification. To remove debris, wastewater is passed through a screen with rods. Cleaning is automatic, and operators also check the quality of contaminant removal every hour. There are new self-cleaning grilles, but they are more expensive.
For clarification, clarifiers, filters, and settling tanks are used. In settling tanks and clarifiers, water moves very slowly, as a result of which suspended particles begin to fall out to form sediment. From the sand traps, the liquid is directed to the primary settling tanks - mineral impurities also settle here, and light suspensions rise to the surface. The sediment is formed at the bottom; it is raked into pits using a truss with a scraper. The floating substances are sent to the grease trap, from there to the well and rolled away. 
The clarified water masses are sent to patches, then to aeration tanks. At this point, the mechanical removal of impurities can be considered complete - the turn of the biological one comes. The aeration tanks include 4 corridors, into the first one silt is supplied through tubes, and the water acquires a brown tint, continuing to be actively saturated with oxygen. The sludge contains microorganisms that also purify the water. The water is then sent to a secondary settling tank where it is separated from the sludge. The sludge goes through pipes into wells, from where pumps pump it into aeration tanks. Water is poured into contact-type tanks, where it was previously chlorinated, but now in transit.
It turns out that during primary purification, water is simply poured into a vessel, infused and drained. But this is precisely what makes it possible to remove most of the organic impurities at minimal financial cost. After water leaves the primary settling tanks, it goes to other water treatment facilities. Secondary purification involves the removal of organic residues. This is a biological stage. The main types of systems are activated sludge and trickling biological filters.
Through three collectors from the city, dirty water is supplied to mechanical screens ( the optimal gap is 16 mm), passes through them, the largest contaminant particles are deposited on the grid. Cleaning is automatic. Mineral impurities, which have a significant mass compared to water, follow through the hydraulic elevators, after which the hydraulic elevators are rolled back to the launch pads.
After leaving the sand traps, the water enters the primary settling tank (there are 4 in total). The floating substances are fed into the grease trap, from the grease trap into the well and rolled away. All operating principles described in this section are valid for different types of treatment systems, but may have certain variations taking into account the characteristics of a particular complex.
To choose the right treatment system, be sure to consider the type of wastewater. Available options:
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 wastewater treatment plants 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:
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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.
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).
This subsidiary of the petrochemical company SIBUR is one of the largest producers of high-quality rubbers, latexes and thermoplastic elastomers in Russia.
01
. Our guide to the world of high technologies for wastewater, process and, of course, sewage water treatment, press officer Ksenia deals with security. After a slight hitch, we are still allowed into the territory. 
02
. Exterior view of the complex. Part of the cleaning process takes place inside the building, but some stages are also outdoors. 
03
. Let me make a reservation right away that this complex processes only wastewater from Voronezhsintezkauchuk and does not touch the city sewerage system, so readers who are chewing at the moment, in principle, do not have to worry about their appetite. When I learned about this, I was somewhat upset, because I wanted to ask the staff about mutant rats, corpses and other horrors. So, one of two supply pressure pipelines with a diameter of 700 mm (the second is a reserve one). 
04
. First of all, wastewater enters the mechanical treatment area. It includes 4 Rotamat Ro5BG9 mechanical wastewater treatment units from HUBER (3 in operation, 1 in reserve), combining fine-slit drum screens and highly efficient aerated sand traps. Waste from the grates and sand after squeezing are fed using conveyors into bunkers with a sluice gate. The sludge from the grates is sent to a landfill, but can also be used as filler in sludge composting. Sand is stored on special sand sites. 
05
. In addition to Ksenia, we were accompanied by the head of the workshop, Alexander Konstantinovich Charkin. He said that he didn’t like to be photographed, so I clicked him, just in case, as he enthusiastically told us how sand traps work. 
06
. In order to smooth out the uneven flow of industrial wastewater from an enterprise, it is necessary to average the wastewater by volume and composition. Therefore, due to cyclic fluctuations in the concentration and composition of pollutants, the water then ends up in so-called homogenizers. There are two of them here. 
07
. They are equipped with systems for mechanical mixing of wastewater. The total capacity of the two homogenizers is 7580 m3. 
08
. You can try to blow off the foam. 
09
. After averaging by volume and composition, wastewater is supplied to flotation tanks for treatment using submersible pumps. 
10
. Flotators are 4 flotation units (3 in operation, 1 in reserve). Each flotator is equipped with a flocculator, a thin-layer sedimentation tank, control, measuring and dosing equipment, an air compressor, a recirculation water supply system, etc. 
11
. They saturate part of the water with air and supply a coagulant to remove latex and other suspended substances 
12
. Pressure flotation allows light suspended solids or emulsions to be separated from the liquid phase using air bubbles and reagents. Aluminum hydroxychloride (about 10 g/m3 of wastewater) is used as a coagulant. 
13
. To reduce reagent consumption and increase flotation efficiency, a cationic flocculant is used, for example, Zetag 7689 (about 0.8 g/m3). 
14
. Mechanical sludge dewatering workshop (MSD). Here, sludge from flotation tanks and activated sludge after biological treatment and post-treatment are dewatered. 
15
. Mechanical dewatering of sludge is carried out on belt filter presses (belt width 2 m) with the addition of a working solution of a cationic flocculant. In emergency situations, sludge is supplied to emergency sludge sites. 
16
. The dehydrated sludge is sent for disinfection and further drying to a turbo dryer (VOMM Ecologist-900) with a final humidity of 20%, or to storage areas. 
17
.
18
. The filtrate and dirty wash water are drained into the dirty water tank. 
19
. Unit for preparing and dosing the flocculant working solution. 
20
. Behind the green door from the previous photo is an autonomous boiler room. 
21
. Biological treatment according to the project is carried out in biotanks using loading material KS-43 KPP/1.2.3 produced by Ecopolymer. Biotanks are 2-corridor with a corridor size of 54x4.5x4.4 m (each capacity is 2100 m3). With transverse sectioning by installing lightweight partitions. With the placement of containers with carriers of fixed biomass and a polymer aeration system. Unfortunately, I completely forgot to take a closer photo of them. 
22.
Blower station. Equipment – centrifugal blowers Q = 7000 m3/h, 3 pcs. (2 – in operation, 1 – in reserve). Air is used for aeration and regeneration of biotanks loading, as well as washing of post-treatment filters. 
23
. Post-treatment is carried out using fast, non-pressure sand filters. 
24
. Number of filters – 10 pcs. The number of sections in the filter is two. Dimensions of one filter section: 5.6x3.0 m.
The useful filtering area of one filter is 16.8 m2. 
25
. Filter media – quartz sand with an equivalent diameter of 4 mm, layer height – 1.4 m. The amount of loading material per filter is 54 m3, the volume of gravel is 3.4 m3 (unfractionated gravel with a height of 0.2 m). 
26
. Next, the treated wastewater undergoes disinfection using a UV installation TAK55M 5-4x2i1 (option with post-treatment) manufactured by Wedeco. 
27
. The installation capacity is 1250 m3/h.
28
. Wash waters from biotanks, rapid filters, sludge water from sludge compactors, filtrate, and wash waters from the central treatment facility are accumulated in the dirty water reservoir. 
29
. Perhaps this is the most colorful place we have seen =) 
30
. From the reservoir, water is supplied to radial settling tanks for clarification. They are used to clarify wastewater from on-site sewage systems: filtrate and wash water from mechanical dewatering of sludge, effluent from emptying biotanks during regeneration, dirty wash water from rapid post-treatment filters, sludge water from compactors. Clarified water is sent to biotanks, sludge - to a sludge compactor (in emergency situations - directly to a sludge mixing tank in front of the central treatment facility). Removal of floating substances is maintained. 
31
. There are two of them. One was full and fragrant. 
32. And the second one was actually empty. 
33
. MCC 
34
. Operator. 
35
. Basically, that's all. The cleaning process is complete. After UV disinfection, the water flows into a collection chamber, and from it through a gravity collector further to the point of discharge into the Voronezh reservoir. The described technological process fully ensures the fulfillment of the requirements for the quality of treated wastewater discharged into a surface reservoir for fishing purposes. And let this picture serve as a group photo as a souvenir for the excursion participants. 
is a complex of special structures designed to purify wastewater from the contaminants it contains. Purified water is either used further or discharged into natural reservoirs (Great Soviet Encyclopedia).
Every settlement needs effective wastewater treatment plants. The operation of these complexes determines what water will enter the environment and how this will subsequently affect the ecosystem. If liquid waste is not cleaned up at all, not only will plants and animals die, but the soil will also be poisoned, and harmful bacteria can enter the human body and cause serious consequences.
Every enterprise that has toxic liquid waste is required to operate a treatment plant system. Thus, this will affect the state of nature and improve human living conditions. If treatment systems work effectively, wastewater will become harmless when it enters the ground and water bodies. The size of treatment facilities (hereinafter - OS) and the complexity of treatment strongly depend on the contamination of wastewater and its volume. More details about the stages of wastewater treatment and types of O.S. read on.
The most indicative in terms of the presence of water purification stages are urban or local OS, designed for large populated areas. It is household wastewater that is most difficult to treat, as it contains various pollutants.
It is typical for sewerage water treatment facilities that they are built in a certain sequence. Such a complex is called a treatment plant line. The scheme begins with mechanical cleaning. Grates and sand traps are most often used here. This is the initial stage of the entire water treatment process.
This could be leftover paper, rags, cotton wool, bags and other debris. After the grates, sand traps come into operation. They are necessary in order to retain sand, including large sizes.
Initially, all water from the sewer enters the main pumping station into a special reservoir. This reservoir is designed to compensate for the increased load during peak hours. A powerful pump evenly pumps the appropriate volume of water to pass through all stages of cleaning.
catch large debris larger than 16 mm - cans, bottles, rags, bags, food, plastic, etc. Subsequently, this waste is either processed on site or transported to sites for processing solid household and industrial waste. The gratings are a type of transverse metal beams, the distance between which is several centimeters.
In fact, they catch not only sand, but also small pebbles, glass fragments, slag, etc. Sand settles to the bottom quite quickly under the influence of gravity. Then the settled particles are raked by a special device into a recess at the bottom, from where they are pumped out. The sand is washed and disposed of.
. Here all impurities that float to the surface of the water (fats, oils, petroleum products, etc.) are removed. By analogy with a sand trap, they are also removed with a special scraper, only from the surface of the water.
4. Settling tanks– an important element of any treatment plant line. In them, water is freed from suspended substances, including helminth eggs. They can be vertical and horizontal, single-tier and two-tier. The latter are the most optimal, since in this case the water from the sewer in the first tier is purified, and the sediment (silt) that has formed there is discharged through a special hole into the lower tier. How does the process of releasing suspended solids from sewer water take place in such structures? The mechanism is quite simple. Sedimentation tanks are large, round or rectangular shaped tanks where substances settle under the influence of gravity.
To speed up this process, you can use special additives - coagulants or flocculants. They promote the sticking together of small particles due to a change in charge; larger substances settle faster. Thus, sedimentation tanks are indispensable structures for purifying water from sewers. It is important to take into account that they are also actively used in simple water treatment. The principle of operation is based on the fact that water enters from one end of the device, while the diameter of the pipe at the exit becomes larger and the flow of liquid slows down. All this contributes to the sedimentation of particles.
mechanical wastewater treatment can be used depending on the degree of water contamination and the design of a specific treatment facility. These include: membranes, filters, septic tanks, etc.
If we compare this stage with conventional water treatment for drinking purposes, then in the latter version such structures are not used and there is no need for them. Instead, processes of water clarification and discoloration occur. Mechanical cleaning is very important, since in the future it will allow for more effective biological treatment.
Biological treatment can be either an independent treatment facility or an important stage in a multi-stage system of large urban treatment complexes.
The essence of biological treatment is to remove various pollutants (organics, nitrogen, phosphorus, etc.) from water using special microorganisms (bacteria and protozoa). These microorganisms feed on harmful contaminants contained in the water, thereby purifying it.
From a technical point of view, biological treatment is carried out in several stages:
– a rectangular tank where water, after mechanical purification, is mixed with activated sludge (special microorganisms), which purifies it. Microorganisms are of 2 types:
Necessary for removing unpleasantly smelling air with its subsequent purification. This workshop is necessary when the volume of wastewater is large enough and/or treatment facilities are located near populated areas.
Here the water is purified from activated sludge by settling it. Microorganisms settle to the bottom, where they are transported to the pit using a bottom scraper. A surface scraper mechanism is provided to remove floating sludge.
The purification scheme also includes sludge digestion. The most important treatment facility is the digester. It is a reservoir for the fermentation of sludge, which is formed during settling in two-tier primary settling tanks. During the fermentation process, methane is produced, which can be used in other technological operations. The resulting sludge is collected and transported to special sites for thorough drying. Sludge beds and vacuum filters are widely used for sludge dewatering. After this, it can be disposed of or used for other needs. Fermentation occurs under the influence of active bacteria, algae, and oxygen. The sewer water purification scheme may also include biofilters.
It is best to place them before the secondary settling tanks, so that substances that are carried away with the flow of water from the filters can settle in the settling tanks. It is advisable to use so-called pre-aerators to speed up cleaning. These are devices that help saturate water with oxygen to accelerate aerobic processes of oxidation of substances and biological treatment. It should be noted that sewerage water purification is conventionally divided into 2 stages: preliminary and final.
The treatment plant system may include biofilters instead of filtration and irrigation fields.
- These are devices where wastewater is purified by passing through a filter containing active bacteria. It consists of solid substances, which can be granite chips, polyurethane foam, polystyrene foam and other substances. A biological film consisting of microorganisms forms on the surface of these particles. They decompose organic matter. As biofilters become dirty, they need to be cleaned periodically.
Wastewater is fed into the filter in doses, otherwise high pressure can destroy beneficial bacteria. After biofilters, secondary settling tanks are used. The sludge formed in them goes partly into the aeration tank, and the rest of it goes to the sludge compactors. The choice of one or another biological treatment method and type of treatment facility largely depends on the required degree of wastewater treatment, topography, soil type and economic indicators. 
After passing through the main stages of treatment, 90-95% of all contaminants are removed from wastewater. But the remaining pollutants, as well as residual microorganisms and their metabolic products, do not allow this water to be discharged into natural reservoirs. In this regard, various wastewater treatment systems were introduced at wastewater treatment plants.
In bioreactors the process of oxidation of the following pollutants occurs:
This happens by creating conditions for the development of autotrophic microorganisms, i.e. converting inorganic compounds into organic ones. For this purpose, special plastic backfill discs with a high specific surface area are used. Simply put, these are disks with a hole in the center. To speed up processes in the bioreactor, intensive aeration is used.
Filters purify water using sand. The sand is continuously updated automatically. Filtration is carried out in several installations by supplying water to them from the bottom up. In order to avoid using pumps and not wasting electricity, these filters are installed at a level lower than other systems. Filter washing is designed in such a way that it does not require a large amount of water. Therefore, they do not occupy such a large area.
Disinfection or disinfection of water is an important component that ensures its safety for the body of water into which it will be discharged. Disinfection, that is, the destruction of microorganisms, is the final stage of sewerage wastewater treatment. A wide variety of methods can be used for disinfection: ultraviolet irradiation, alternating current, ultrasound, gamma irradiation, chlorination.
Ural irradiation is a very effective method that destroys approximately 99% of all microorganisms, including bacteria, viruses, protozoa, and helminth eggs. It is based on the ability to destroy the membrane of bacteria. But this method is not used so widely. In addition, its effectiveness depends on the turbidity of the water and the content of suspended substances in it. And UV lamps quickly become covered with a coating of mineral and biological substances. To prevent this, special emitters of ultrasonic waves are provided.
The most commonly used method after treatment facilities is chlorination. Chlorination can be different: double, superchlorination, with preammonization. The latter is necessary to prevent unpleasant odors. Superchlorination involves exposure to very large doses of chlorine. Double action means that chlorination is carried out in 2 stages. This is more typical for water treatment. The method of chlorinating sewer water is very effective, in addition, chlorine has an aftereffect that other cleaning methods cannot boast of. After disinfection, the wastewater is discharged into a reservoir.
Phosphates are salts of phosphoric acids. They are widely used in synthetic detergents (washing powders, dishwashing detergents, etc.). Phosphates entering water bodies lead to their eutrophication, i.e. turning into a swamp.
Purification of wastewater from phosphates is carried out by dosed addition of special coagulants to the water before biological treatment facilities and before sand filters.
is the active process of saturating water with air, in this case by passing air bubbles through the water. Aeration is used in many processes in wastewater treatment plants. Air supply is carried out by one or more blowers with frequency converters. Special oxygen sensors regulate the amount of air supplied so that its content in the water is optimal.
At the biological stage of wastewater treatment, excess sludge is formed, as microorganisms actively multiply in aeration tanks. Excess sludge is dewatered and disposed of.
The dehydration process takes place in several stages:
Unfortunately, wastewater treatment plants don't smell the best. The biological wastewater treatment stage is especially smelly. Therefore, if the treatment plant is located near populated areas or the volume of wastewater is so large that a lot of bad-smelling air is generated, you need to think about cleaning not only the water, but also the air.
Air purification usually takes place in 2 stages:
All water that leaves treatment plants must be systematically monitored in the laboratory. The laboratory determines the presence of harmful impurities in water and whether their concentrations comply with established standards. If one or another indicator is exceeded, treatment plant workers conduct a thorough inspection of the corresponding treatment stage. And if a malfunction is detected, it is eliminated.
The personnel servicing the treatment plant can reach several dozen people. For their comfortable work, an administrative and amenity complex is being created, which includes:
Power supply O.S. performed according to the first reliability category. Since a long shutdown of O.S. due to lack of electricity may cause O.S. output. out of service.
To prevent emergency situations, power supply O.S. carried out from several independent sources. The branch of the transformer substation provides for the input of a power cable from the city power supply system. As well as the introduction of an independent source of electric current, for example, from a diesel generator, in case of an emergency in the city power grid.
Based on all of the above, we can conclude that the design of treatment facilities is very complex and includes various stages of treating wastewater from sewers. First of all, you need to know that this scheme applies only to domestic wastewater. If industrial wastewater occurs, then in this case special methods are additionally included that will be aimed at reducing the concentration of hazardous chemicals. In our case, the cleaning scheme includes the following main stages: mechanical, biological cleaning and disinfection (disinfection).
Mechanical cleaning begins with the use of grates and sand traps, which trap large debris (rags, paper, cotton wool). Sand traps are needed to sediment excess sand, especially coarse sand. This is of great importance for subsequent stages. After screens and sand traps, the sewer water treatment plant scheme includes the use of primary settling tanks. Suspended substances settle in them under the force of gravity. To speed up this process, coagulants are often used.
After settling tanks, the filtration process begins, which is carried out mainly in biofilters. The mechanism of action of the biofilter is based on the action of bacteria that destroy organic substances.
The next stage is secondary settling tanks. The silt that was carried away by the current of liquid settles in them. After them, it is advisable to use a digester, in which the sludge is fermented and transported to sludge sites.
The next stage is biological treatment using an aeration tank, filtration fields or irrigation fields. The final stage is disinfection.
A variety of structures are used for water treatment. If it is planned to carry out this work on surface water immediately before its supply to the city’s distribution network, then the following structures are used: settling tanks, filters. For wastewater, a wider range of devices can be used: septic tanks, aeration tanks, digesters, biological ponds, irrigation fields, filtration fields, and so on. There are several types of treatment plants depending on their purpose. They differ not only in the volume of water being purified, but also in the presence of stages of its purification.
Data from O.S. are the largest of all, they are used in large cities and towns. In such systems, particularly effective methods of liquid purification are used, for example, chemical treatment, methane tanks, flotation units. They are designed for the treatment of municipal wastewater. These waters are a mixture of domestic and industrial wastewater. Therefore, there are a lot of pollutants in them, and they are very diverse. The water is purified to meet the standards for discharge into a fishery reservoir. The standards are regulated by Order of the Ministry of Agriculture of Russia dated December 13, 2016 No. 552 “On approval of water quality standards for water bodies of fishery importance, including standards for maximum permissible concentrations of harmful substances in the waters of water bodies of fishery importance.”
In OS data, as a rule, all stages of water purification described above are used. The most illustrative example is the Kuryanovsky wastewater treatment plant.
Kuryanovsky O.S. are the largest in Europe. Its capacity is 2.2 million m3/day. They serve 60% of Moscow's wastewater. The history of these objects goes back to 1939.
Local treatment facilities are structures and devices designed to treat the subscriber's wastewater before discharging it into the public sewerage system (defined by Decree of the Government of the Russian Federation of February 12, 1999 No. 167).
There are several classifications of local OS, for example, there are local OS. connected to the central sewerage and autonomous. Local O.S. can be used on the following objects:
Local O.S. can vary greatly from small units to capital structures that are maintained daily by qualified personnel.
Several solutions are used to dispose of wastewater from a private home. They all have their advantages and disadvantages. However, the choice always remains with the home owner.
1. Cesspool. In truth, this is not even a treatment facility, but simply a tank for temporary storage of wastewater. When the pit is filled, a sewage disposal truck is called, which pumps out the contents and takes it away for further processing.
This archaic technology is still used today due to its cheapness and simplicity. However, it also has significant disadvantages, which sometimes negate all its advantages. Wastewater can enter the environment and groundwater, thereby polluting it. It is necessary to provide a normal entrance for the sewer truck, since it will have to be called quite often.
2. Storage. It is a container made of plastic, fiberglass, metal or concrete into which wastewater is drained and stored. They are then pumped out and disposed of by a sewer truck. The technology is similar to a cesspool, but the water does not pollute the environment. The disadvantage of such a system is the fact that in the spring, when there is a large amount of water in the ground, the storage tank can be squeezed out to the surface of the earth.
3. Septic tank- are large containers, in which substances such as coarse dirt, organic compounds, stones and sand precipitate, and elements such as various oils, fats and petroleum products remain on the surface of the liquid. The bacteria that live inside the septic tank extract oxygen for life from the fallen sediment, while reducing the level of nitrogen in the wastewater. When the liquid leaves the sump, it becomes clarified. It is then purified using bacteria. However, it is important to understand that phosphorus remains in such water. For final biological treatment, irrigation fields, filtration fields or filter wells can be used, the operation of which is also based on the action of bacteria and activated sludge. Plants with a deep root system cannot be grown in this area.
A septic tank is very expensive and can take up a large area. It should be borne in mind that this is a structure that is designed to treat small amounts of domestic wastewater from the sewer system. However, the result is worth the money spent. The structure of a septic tank is shown more clearly in the figure below. 
4. Deep biological treatment stations are already a more serious treatment facility, unlike a septic tank. This device requires electricity to operate. However, the quality of water purification is up to 98%. The design is quite compact and durable (up to 50 years of operation). To service the station, there is a special hatch at the top, above the ground surface.
Despite the fact that rainwater is considered quite clean, it collects various harmful elements from asphalt, roofs and lawns. Garbage, sand and petroleum products. To ensure that all this does not end up in nearby water bodies, stormwater treatment facilities are being created.
In them, water undergoes mechanical purification in several stages:
Design of O.S. determine their cost, choose the right treatment technology, ensure reliable operation of the structure, and bring wastewater to quality standards. Experienced specialists will help you find effective installations and reagents, draw up a wastewater treatment plan and put the installation into operation. Another important point is drawing up an estimate that will allow you to plan and control expenses, as well as make adjustments if necessary.
For the project O.S. The following factors greatly influence:
Stages of designing a treatment plant:
After the O.S. project has been prepared and all necessary permits have been obtained, the installation stage begins. Although the installation of a country septic tank is very different from the construction of a sewage treatment plant in a cottage community, they still go through several stages.
First, the area is prepared. A pit is being dug to install a treatment plant. The floor of the pit is filled with sand and compacted or concreted. If a treatment plant is designed for a large amount of wastewater, then, as a rule, it is built on the surface of the ground. In this case, the foundation is poured and a building or structure is already installed on it.
Secondly, the installation of equipment is carried out. It is installed, connected to the sewerage and drainage system, and to the electrical network. This stage is very important because it requires personnel to know the specifics of the operation of the equipment being configured. It is incorrect installation that most often causes equipment failure.
Thirdly, inspection and delivery of the object. After installation, the finished treatment facility is tested for the quality of water treatment, as well as for its ability to operate under high load conditions. After checking O.S. is handed over to the customer or his representative, and also, if necessary, undergoes a state control procedure.
Like any equipment, the treatment plant also needs maintenance. Primarily from O.S. It is necessary to remove large debris, sand, and excess silt that are formed during cleaning. On large O.S. the number and type of elements removed can be significantly greater. But in any case, they will have to be deleted.
Secondly, the functionality of the equipment is checked. Malfunctions in any element can lead not only to a decrease in the quality of water purification, but also to the failure of all equipment.
Thirdly, if a breakdown is detected, the equipment must be repaired. And it’s good if the equipment is under warranty. If the warranty period has expired, then repair O.S. you will have to do it at your own expense.
Today we will once again talk about a topic close to each of us, without exception.
Most people, when they press the toilet button, don't think about what happens to what they flush. It leaked and flowed, that's business. In a large city like Moscow, no less than four million cubic meters of wastewater flow into the sewer system every day. This is approximately the same amount of water flowing in the Moscow River in a day opposite the Kremlin. All this huge volume of wastewater needs to be purified and this is a very difficult task.
Moscow has two largest wastewater treatment plants of approximately the same size. Each of them purifies half of what Moscow “produces.” I have already spoken in detail about the Kuryanovskaya station. Today I will talk about the Lyubertsy station - we will again go over the main stages of water purification, but we will also touch on one very important topic - how treatment stations fight unpleasant odors using low-temperature plasma and waste from the perfume industry, and why this problem has become more relevant than ever .
First, a little history. For the first time, sewerage “came” to the area of modern Lyubertsy at the beginning of the twentieth century. Then the Lyubertsy irrigation fields were created, in which wastewater, still using old technology, seeped through the ground and was thereby purified. Over time, this technology became unacceptable for the ever-increasing amount of wastewater and in 1963 a new treatment station was built - Lyuberetskaya. A little later, another station was built - Novolubertskaya, which actually borders the first one and uses part of its infrastructure. In fact, now it is one large cleaning station, but consisting of two parts - old and new.
Let's look at the map - on the left, in the west - the old part of the station, on the right, in the east - the new one:
The station area is huge, about two kilometers in a straight line from corner to corner.
As you might guess, there is a smell coming from the station. Previously, few people worried about it, but now this problem has become relevant for two main reasons:
1) When the station was built, in the 60s, practically no one lived around it. Nearby there was a small village where the station workers themselves lived. At that time this area was far, far from Moscow. Now there is very active construction going on. The station is virtually surrounded on all sides by new buildings and there will be even more of them. New houses are even being built on the station’s former sludge sites (fields to which sludge left over from wastewater treatment was transported). As a result, residents of nearby houses are forced to periodically sniff “sewer” odors, and of course they constantly complain.
2) Sewage water has become more concentrated than before, in Soviet times. This happened due to the fact that the volume of water used has recently decreased significantly, while people have not gone to the toilet less, but on the contrary, the population has grown. There are quite a few reasons why the amount of “diluting” water has become much smaller:
a) use of meters - water has become more economical;
b) the use of more modern plumbing - it is increasingly rare to see a running faucet or toilet;
c) use of more economical household appliances - washing machines, dishwashers, etc.;
d) closure of a huge number of industrial enterprises that consumed a lot of water - AZLK, ZIL, Serp and Molot (partially), etc.
As a result, if the station during construction was designed for a volume of 800 liters of water per person per day, now this figure is actually no more than 200. An increase in concentration and a decrease in flow led to a number of side effects - sediment began to be deposited in sewer pipes designed for a higher flow, leading to to unpleasant odors. The station itself began to smell more.
To combat the smell, Mosvodokanal, which manages the treatment facilities, is carrying out a phased reconstruction of the facilities, using several different methods of getting rid of odors, which will be discussed below.
Let's go in order, or rather, in the flow of water. Wastewater from Moscow enters the station through the Lyubertsy sewer canal, which is a huge underground collector filled with wastewater. The canal is gravity-flowing and runs at a very shallow depth almost throughout its entire length, and sometimes even above the ground. Its scale can be appreciated from the roof of the administrative building of the wastewater treatment plant:
The width of the canal is about 15 meters (divided into three parts), the height is 3 meters.
At the station, the channel enters the so-called receiving chamber, from where it is divided into two streams - part goes to the old part of the station, part to the new one. The receiving chamber looks like this:
The channel itself comes from the right-back, and the flow, divided into two parts, leaves through the green channels in the background, each of which can be blocked by a so-called gate - a special shutter (dark structures in the photo). Here you can notice the first innovation to combat odors. The receiving chamber is completely covered with sheets of metal. Previously, it looked like a “swimming pool” filled with fecal water, but now it is not visible; naturally, the solid metal coating almost completely blocks the smell.
For technological purposes, only a very small hatch was left, by lifting it you can enjoy the whole bouquet of smells.
These huge gates allow you to block the channels coming from the receiving chamber if necessary.
There are two channels from the receiving chamber. They, too, were open quite recently, but now they are completely covered with a metal ceiling.
Gases released from wastewater accumulate under the ceiling. These are mainly methane and hydrogen sulfide - both gases are explosive at high concentrations, so the space under the ceiling must be ventilated, but here the following problem arises - if you just install a fan, then the whole point of the ceiling will simply disappear - the smell will get outside. Therefore, to solve the problem, MKB "Horizon" developed and manufactured a special installation for air purification. The installation is located in a separate booth and a ventilation pipe from the duct goes to it.
This installation is experimental, to test the technology. In the near future, such installations will begin to be installed en masse at treatment plants and at sewerage pumping stations, of which there are more than 150 in Moscow and from which unpleasant odors also emanate. On the right in the photo is one of the developers and testers of the installation, Alexander Pozinovsky.
The operating principle of the installation is as follows:
Polluted air is supplied into four vertical stainless steel pipes from below. These same pipes contain electrodes, to which high voltage (tens of thousands of volts) is applied several hundred times per second, resulting in discharges and low-temperature plasma. When interacting with it, most smelling gases turn into a liquid state and settle on the walls of the pipes. A thin layer of water constantly flows down the walls of the pipes, with which these substances mix. The water circulates in a circle, the water tank is the blue container on the right, below in the photo. Purified air comes out of stainless steel pipes from above and is simply released into the atmosphere.
For patriots - the installation was completely developed and created in Russia, with the exception of the power stabilizer (bottom in the cabinet in the photo). High voltage part of the installation:
Since the installation is experimental, it contains additional measuring equipment - a gas analyzer and an oscilloscope.
The oscilloscope shows the voltage across the capacitors. During each discharge, the capacitors are discharged and the process of their charging is clearly visible on the oscillogram.
There are two tubes going to the gas analyzer - one takes in air before installation, the other after. In addition, there is a faucet that allows you to select the tube that connects to the gas analyzer sensor. Alexander first shows us the “dirty” air. Hydrogen sulfide content - 10.3 mg/m3. After switching the tap, the content drops to almost zero: 0.0-0.1.
Next, the supply channel abuts a special distribution chamber (also covered with metal), where the flow is divided into 12 parts and goes further into the so-called grid building, which is visible in the background. There, wastewater undergoes the very first stage of purification - removal of large debris. As you might guess from the name, it is passed through special gratings with a cell size of about 5-6 mm.
Each of the channels is also blocked by a separate gate. Generally speaking, there are a huge number of them at the station - sticking out here and there
After cleaning from large debris, the water enters sand traps, which, as again it is not difficult to guess from the name, are designed to remove small solid particles. The principle of operation of sand traps is quite simple - essentially it is a long rectangular tank in which water moves at a certain speed, as a result the sand simply has time to settle. Air is also supplied there, which facilitates the process. Sand is removed from below using special mechanisms.
As often happens in technology, the idea is simple, but the execution is complex. So here too - visually this is the most sophisticated design on the way to water purification.
Sand traps are favored by seagulls. In general, there were a lot of seagulls at the Lyubertsy station, but it was in the sand traps that there were the most of them.
I enlarged the photo at home and laughed at the sight of them - funny birds. They are called black-headed gulls. No, they don’t have a dark head because they constantly dip it where it shouldn’t, it’s just a design feature
Soon, however, they will have a hard time - many open water surfaces at the station will be covered.
Let's get back to technology. The photo shows the bottom of the sand trap (not working at the moment). This is where the sand settles and is removed from there.
After the sand traps, the water again flows into the common channel.
Here you can see what all the channels at the station looked like before they began to be covered. This channel is closing right now.
The frame is made of stainless steel, like most metal structures in the sewer system. The fact is that the sewer system has a very aggressive environment - water full of all sorts of substances, 100% humidity, gases that promote corrosion. Ordinary iron very quickly turns to dust in such conditions.
The work is being carried out directly above the active channel - since this is one of the two main channels, it cannot be turned off (Muscovites will not wait :)).
In the photo there is a small level difference, about 50 centimeters. The bottom in this place is made of a special shape to dampen the horizontal velocity of the water. The result is very active seething.
After sand traps, water flows to primary settling tanks. In the photo - in the foreground there is a chamber into which water flows, from which it flows into the central part of the sump in the background.
A classic sump looks like this:
And without water - like this:
Dirty water comes from a hole in the center of the sump and enters the general volume. In the settling tank itself, the suspension contained in the dirty water gradually settles to the bottom, along which a sludge scraper, mounted on a truss rotating in a circle, constantly moves. The scraper scrapes the sediment into a special ring tray, and from it, in turn, it falls into a round pit, from where it is pumped out through a pipe by special pumps. Excess water flows into a channel laid around the sump and from there into the pipe.
Primary settling tanks are another source of unpleasant odors at the plant, because... they contain actually dirty (purified only from solid impurities) sewage water. In order to get rid of the smell, Moskvodokanal decided to cover the sedimentation tanks, but a big problem arose. The diameter of the sump is 54 meters (!). Photo with a person for scale:
Moreover, if you make a roof, then it must, firstly, withstand snow loads in winter, and secondly, have only one support in the center - supports cannot be made above the sump itself, because the farm is constantly rotating there. As a result, an elegant solution was made - to make the ceiling floating.
The ceiling is assembled from floating stainless steel blocks. Moreover, the outer ring of blocks is fixed motionless, and the inner part rotates floating, together with the truss.
This decision turned out to be very successful, because... firstly, the problem with snow load disappears, and secondly, there is no volume of air that would have to be ventilated and additionally purified.
According to Mosvodokanal, this design reduced emissions of odorous gases by 97%.
This settling tank was the first and experimental one where this technology was tested. The experiment was considered successful and now other settling tanks at the Kuryanovskaya station are already covered in a similar way. Over time, all primary settling tanks will be covered in a similar manner.
However, the reconstruction process is lengthy - it is impossible to turn off the entire station at once; the settling tanks can only be reconstructed one after another, turning off one by one. Yes, and a lot of money is needed. Therefore, while not all sedimentation tanks are covered, a third method of combating odors is used - spraying neutralizing substances.
Special sprayers were installed around the primary settling tanks, which create a cloud of substances that neutralize odors. The substances themselves smell, not very pleasant or unpleasant, but quite specific, however, their task is not to mask the smell, but to neutralize it. Unfortunately, I don’t remember the specific substances that are used, but as they said at the station, these are waste products from the French perfume industry.
For spraying, special nozzles are used that create particles with a diameter of 5-10 microns. The pressure in the pipes, if I'm not mistaken, is 6-8 atmospheres.
After the primary settling tanks, the water enters aeration tanks - long concrete tanks. They supply a huge amount of air through pipes and also contain activated sludge - the basis of the entire biological method. Activated sludge processes “waste” and multiplies quickly. The process is similar to what happens in nature in reservoirs, but it proceeds many times faster due to warm water, a large amount of air and silt.
The air is supplied from the main machine room, in which turbo blowers are installed. Three turrets above the building are air intakes. The air supply process requires a huge amount of electricity, and stopping the air supply leads to catastrophic consequences, because activated sludge dies very quickly, and its restoration can take months (!).
Aerotanks, oddly enough, do not particularly emit strong unpleasant odors, so there are no plans to cover them.
This photo shows how dirty water enters the aeration tank (dark) and mixes with activated sludge (brown).
Some of the structures are currently shut down and mothballed, for reasons that I wrote about at the beginning of the post - a decrease in water flow in recent years.
After the aeration tanks, the water enters secondary settling tanks. Structurally, they completely repeat the primary ones. Their purpose is to separate activated sludge from already purified water.
Preserved secondary settling tanks. 
Secondary settling tanks do not smell - in fact, the water here is already clean.
The water collected in the sump ring tray flows into the pipe. Part of the water undergoes additional UV disinfection and is discharged into the Pekhorka River, while part of the water goes through an underground canal to the Moscow River.
The settled activated sludge is used to produce methane, which is then stored in semi-underground reservoirs - methane tanks and used at its own thermal power plant.
The spent sludge is sent to sludge sites in the Moscow region, where it is further dewatered and either buried or burned.
