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 bodies of water. 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.

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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 waste 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 . The filter media is quartz sand with an equivalent diameter of 4 mm, the layer height is 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, sediment - to the sludge compactor (in emergency situations - directly to the sediment mixing tank in front of the central treatment center). 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.

Before designing treatment facilities for domestic wastewater or other types of wastewater, it is important to find out their volume (the amount of wastewater generated over a certain period of time), the presence of impurities (toxic, insoluble, abrasive, etc.) and other parameters.

Types of wastewater

Wastewater treatment plants are installed for various types of wastewater.

• Domestic wastewater– these are drains from plumbing fixtures (washbasins, sinks, toilets, etc.) of residential buildings, including private houses, as well as institutions, public buildings. Household wastewater is dangerous as a breeding ground for pathogenic bacteria.
• Industrial effluents are formed in enterprises. The category is characterized by the possible presence of various impurities, some of which significantly complicate the purification process. Industrial wastewater treatment plants are usually complex in design and have several stages of treatment. The completeness of such structures is selected in accordance with the composition of the wastewater. Industrial wastewater can be toxic, acidic, alkaline, containing mechanical impurities and even radioactive.
• Storm drains due to the method of formation they are also called superficial. They are also called rain or atmospheric. This type of drainage is a liquid formed on roofs, roads, terraces, and squares during precipitation. Stormwater treatment plants typically include multiple stages and are capable of removing various types of contaminants (organic and mineral, soluble and insoluble, liquid, solid and colloidal) from the liquid. Storm drains are the least dangerous and least polluted of all.

Types of treatment facilities

In order to understand what blocks a treatment complex may consist of, you should know the main types of wastewater treatment facilities.

These include:

• mechanical structures,
• biorefinery installations,
• oxygen saturation units that enrich already purified liquid,
• adsorption filters,
• ion exchange blocks,
• electrochemical installations,
• physical and chemical cleaning equipment,
• disinfection installations.

Effluent treatment equipment also includes structures and tanks for storage and storage, as well as for processing filtered sludge.

Operating principle of the wastewater treatment complex

The complex can implement a scheme of wastewater treatment facilities with above-ground or underground design.
Treatment facilities for domestic wastewater are installed in cottage villages, as well as in small settlements (150-30,000 people), at enterprises, in regional centers, etc.

If the complex is installed on the surface of the earth, it has a modular design. In order to minimize damage, reduce costs and labor costs for repairing underground structures, their bodies are made of materials whose strength allows them to withstand the pressure of soil and groundwater. Among other things, such materials are durable (up to 50 years of service).

To understand the operating principle of wastewater treatment plants, let’s consider how the individual stages of the complex function.

Mechanical cleaning

This stage includes the following types of structures:

• primary settling tanks,
• sand traps,
• debris-retaining grates, etc.

All these devices are designed to eliminate suspended matter, large and small insoluble impurities. The largest inclusions are retained by the grill and fall into a special removable container. The so-called sand traps have limited productivity, therefore, when the intensity of wastewater supply to treatment plants is more than 100 cubic meters. m per day, it is advisable to install two devices in parallel. In this case, their efficiency will be optimal; sand traps will be able to retain up to 60% of suspended matter. The retained sand with water (sand pulp) is discharged to sand pads or to a sand bunker.

Biological treatment

After removing the bulk of insoluble impurities (cleaning the wastewater), the liquid for further purification enters the aeration tank - a complex multifunctional device with extended aeration. The aeration tanks will be divided into sections of aerobic and anaerobic purification, due to which, simultaneously with the breakdown of biological (organic) impurities, phosphates and nitrates are removed from the liquid. This significantly increases the efficiency of the second stage of the treatment complex. The active biomass released from the wastewater is retained in special blocks loaded with polymer material. Such blocks are placed in the aeration zone.

After the aeration tank, the sludge mass passes into a secondary settling tank, where it is separated into activated sludge and treated wastewater.

Additional treatment

Post-treatment of wastewater is carried out using self-cleaning sand filters or using modern membrane filters. At this stage, the amount of suspended solids present in the water is reduced to 3 mg/l.

Disinfection

Disinfection of treated wastewater is carried out by treating the liquid with ultraviolet light. To increase the efficiency of this stage, biological wastewater treatment plants are equipped with additional blowing equipment.

Effluents that have passed all stages of the treatment complex are safe for the environment and can be discharged into a reservoir.

Design of treatment systems

Treatment facilities for industrial wastewater are designed taking into account the following factors:

• groundwater level,
• design, geometry, location of the supply manifold,
• completeness of the system (type and number of blocks determined in advance based on biochemical analysis of wastewater or its predicted composition),
• location of compressor units,
• availability of free access for vehicles that will remove waste trapped by grates, as well as for sewage disposal equipment,
• possible placement of the purified liquid outlet,
• the need to use additional equipment (determined by the presence of specific impurities and other individual characteristics of the object).

Important: Surface wastewater treatment facilities should be designed only by companies or organizations with an SRO certificate.

Installation of installations

The correct installation of treatment facilities and the absence of errors at this stage largely determine the durability of the complexes and their efficiency, as well as the uninterrupted operation - one of the most important indicators.

Installation work includes the following steps:

• development of installation diagrams,
• inspection of the site and determination of its readiness for installation,
• construction work,
• connecting installations to communications and connecting them to each other,
• commissioning, adjustment and adjustment of automation,
• delivery of the object.

The full range of installation work (list of necessary operations, scope of work, time required to complete them and other parameters) are determined based on the characteristics of the object: its productivity, completeness), as well as taking into account the characteristics of the installation site (type of relief, soil, location of groundwater etc.).

Treatment plant maintenance

Timely and professional maintenance of wastewater treatment plants ensures the efficiency of the equipment. Therefore, such work must be performed by specialists.

The scope of work includes:

• removal of retained insoluble inclusions (large debris, sand),
• determining the amount of sludge formed,
• checking oxygen content,
• control of work according to chemical and microbiological indicators,
• checking the functioning of all elements.

The most important stage in the maintenance of local treatment facilities is monitoring the operation and prevention of electrical equipment. Typically, blowers and transfer pumps fall into this category. Ultraviolet disinfection installations also require similar maintenance.

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:

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 Flotenk 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 a 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).

WWTPs operate according to the technological scheme of complete biological treatment, including at the reconstructed facilities of NKTP-I and NKTP-II with the removal of nutrients: the first stage is mechanical treatment, including filtering water on screens, trapping mineral impurities in sand traps and settling water in primary settling tanks ; the second stage is biological water purification in aeration tanks and secondary settling tanks. Part of the biologically treated wastewater is subjected to post-treatment using rapid filters and is used for the needs of industrial enterprises instead of tap water.

With wastewater, a large number of different types of waste enter the WWTP: household items of citizens, waste from food production, plastic containers and plastic bags, as well as construction and other waste. To remove them, mechanized screens with 10 mm gaps are used at the WWTP.

The second stage of mechanical wastewater treatment is sand traps - structures used to remove mineral impurities contained in the incoming water. Mineral contaminants found in wastewater include: sand, clay particles, solutions of mineral salts, mineral oils. Various types of sand traps are used at WWTPs – vertical, horizontal and aerated.

After passing through the first two stages of mechanical treatment, wastewater enters primary settling tanks designed to precipitate undissolved impurities from wastewater. Structurally, all primary settling tanks at WWTPs are open type and have a radial shape, with different diameters - 33, 40 and 54 m.

Clarified wastewater after primary settling tanks undergoes complete biological treatment in aeration tanks. Aero tanks – open reinforced concrete structures of a rectangular shape, 4-corridor type. The working depth of the aeration tanks of the old block is 4 m, the aeration tanks of the NKOS - 6 m. Biological wastewater treatment is carried out using activated sludge with forced air supply.

The sludge mixture from the aeration tanks enters secondary settling tanks, where the process of separating activated sludge from purified water occurs. Secondary settling tanks are structurally similar to primary settling tanks.

The entire volume of wastewater treated at the WWTP is supplied to post-treatment facilities. The productivity of the filtering department is 3 million m 3 /day, which allows the entire volume of biologically purified water to pass through flat slotted sieves. After filtering, part of the water is filtered using rapid filters and used for technical needs as a circulating water supply.

Since 2012, all wastewater that has undergone a full treatment cycle at the Kuryanovsky treatment plant has been subjected to ultraviolet disinfection before being discharged into the Moscow River (capacity 3 million m 3 /day). Due to this, the indicators of bacterial contamination of biologically purified WWTP water reached standard values, which had a beneficial effect on the quality of water in the Moscow River and the sanitary and epidemiological state of the water area as a whole.

Sludge generated at various stages of wastewater treatment is supplied to a single sludge treatment complex, which includes:

• belt thickeners to reduce sludge moisture,
• digesters for digestion and sludge stabilization in thermophilic mode (50-53 0 C),
• decanter centrifuges for sludge dewatering using flocculants.

Dewatered sludge is transported by third parties outside the territory of the treatment plant for the purpose of neutralization/disposal and/or use for the production of finished products.