RU2848815C1 - Method for cleaning and disposing of wastewater from sugar factories - Google Patents

Abstract

FIELD: wastewater treatment.

SUBSTANCE: invention relates to the field of wastewater treatment and disposal at sugar factories and is intended for multi-stage deep biological treatment of wastewater generated during sugar beet processing, as well as wastewater of similar composition from the food industry. Sugar production is characterised by significant volumes of wastewater with a high concentration of organic substances, biogenic elements (nitrogen and phosphorus), suspended particles and significant variability in composition. A distinctive feature of the proposed method is comprehensive step-by-step wastewater treatment, including preliminary mechanical and physicochemical treatment, anaerobic biological treatment with biogas generation, and subsequent aerobic post-treatment. This approach ensures effective removal of organic matter, stabilisation of flow parameters and reduction of the load on subsequent stages, which contributes to achieving stable treated water quality in terms of BOD, COD, suspended solids concentration and nitrogen and phosphorus compound content. An important advantage of the method is the possibility of using biogas obtained at the anaerobic stage for the technological needs of treatment facilities, which reduces the energy dependence of production and increases its environmental sustainability. The technology is adapted to seasonal fluctuations and uneven wastewater inflow, ensures quick start-up and prevents equipment downtime in the off-season. Sludge dewatering and drying processes are optimised, which facilitates further disposal or use of the resulting waste.

EFFECT: increased energy efficiency, reduced operating costs and environmental safety in the treatment of wastewater from sugar factories.

7 cl, 2 dwg

Description

The invention relates to the field of purification and disposal of wastewater from sugar production and can be used for multi-stage deep biological treatment of wastewater generated as a result of the operation of a production facility processing sugar beets, as well as for the purification of industrial wastewater from the food industry of similar composition.

Sugar production is a water-intensive sector of the food industry and generates significant volumes of wastewater, characterized by high concentrations of organic matter, nutrients (nitrogen and phosphorus), and suspended particles. The wastewater composition varies significantly depending on the stage of the production cycle. The main problem is the seasonal nature of the plant's operations and, consequently, the seasonal generation of wastewater. Currently, many plants use anaerobic lagoons to discharge their wastewater. This approach is unsustainable from both an environmental and economic perspective. It leads to the loss of significant land areas, the migration of foul-smelling substances over tens of meters, and groundwater pollution. Therefore, sugar mill wastewater requires multi-stage, in-depth treatment before discharge or return to the production cycle.

High levels of easily oxidizable organic compounds (high BOD and COD values) make it possible to use anaerobic technologies, which provide both efficient organic removal and the generation of biogas—a secondary energy resource. However, for stable operation of anaerobic digesters, preliminary mechanical and physicochemical treatment of wastewater is necessary, ensuring a reduction in suspended solids concentrations and stabilization of flow parameters.

With increasingly stringent regulations on wastewater discharge, rising energy costs, and increasing demands for resource conservation, the implementation of energy-efficient integrated treatment technologies that combine mechanical, physical, chemical, and biological treatments, as well as sludge stabilization and biogas energy production, is becoming increasingly important. Developing such technological solutions tailored to sugar production wastewater is a pressing engineering challenge.

A known method for treating wastewater from the production of high fructose syrup (CN 103739145 A, China, published 23.04.2014, IPC C02F 9/14, C02F 1/52) includes sequential mechanical treatment, coagulation with sedimentation of organic matter, preliminary acidification and anaerobic treatment in a reactor with granulated sludge of the EGSB type with internal circulation, where biogas is formed, after which the effluent is subjected to aerobic post-treatment in an anoxic-aerobic bioreactor and clarification, and the resulting sludge is thickened and dewatered. The disadvantage of this method is the lack of membrane post-treatment and complex utilization of biogas and sludge, which limits the depth and energy efficiency of treatment, as a result of which this method does not fully solve the problem of deep and resource-saving treatment of wastewater from sugar production.

A method for treating wastewater from refined sugar production by electrodialysis in combination with an upflow anaerobic sludge bed and a membrane bioreactor is known (article PMC10224370. Shichang, Xu. Study of wastewater treatment from refined sugar production by electrodialysis in combination with an upflow anaerobic sludge bed and a membrane bioreactor / S. Shichang, Ch. et al. // National library of medicine - USA. - 12 p.). The method includes pre-treatment of wastewater by coagulation and filtration, subsequent removal of salts by electrodialysis, removal of organic matter in a system consisting of an upflow anaerobic reactor with granular activated sludge (UASB) and a membrane bioreactor (MBR). The process achieves a gradual reduction in COD: after UASB, the average COD value is 2048 mg/L, while after MBR, it is 44-69 mg/L. A disadvantage of this method is that it lacks a complete sludge and biogas utilization system, making the process less energy-efficient and environmentally sustainable. Furthermore, no provision is made for operating modes for the treatment facilities during periods of forced downtime or with uneven wastewater inflow, limiting the flexibility and reliability of the technology. Therefore, this method does not fully meet modern requirements for comprehensive and resource-efficient wastewater treatment in sugar production.

A known method for purifying wastewater from bamboo products (patent CN 102329044 B, China, published 13.11.2013, IPC CO2F 9/14, C02F 3/30, C02F 1/66, C02F 1/44, C02F 103/26) includes wastewater dilution, pH adjustment, anaerobic treatment in an expanded granular bed reactor (EGSB), biological treatment in a membrane reactor (MBR), and tertiary treatment by nanofiltration to achieve a high level of organic contaminant removal and obtain purified water. The process also includes the collection and desulfurization of biogas generated as a result of anaerobic decomposition of organic matter, followed by its storage and recirculation. The key objective of this method is to effectively reduce COD and BOD levels during the treatment of highly concentrated industrial wastewater, typical of the pulp and paper industry. A disadvantage of this method is the lack of preliminary mechanical treatment, which leads to the risk of membrane and equipment clogging, as well as the long anaerobic treatment time (100-120 hours), which increases energy consumption and treatment time. Furthermore, the method does not provide for the efficient utilization of biogas for heat generation.

A self-sustaining system with zero impact and zero waste discharge into the energy grid and a method for treating sugar industry wastewater and spent distillery wash water are known (patent WO 2013069026 A1, WIPO (PCT), published 16.05.2013, IPC C02F 3/28, C02F 9/14, C02F 9/04, C02F 9/08). This system includes two sequential stages of anaerobic digestion - with long and short hydraulic retention times - for treating sugar production wastewater, press mud, and distillery stillage. The biogas obtained in the process is purified from hydrogen sulfide and dried, after which it is used to generate electricity and heat. The residual digestate is used to produce solid fuel, while the liquid fraction undergoes membrane purification through a reverse osmosis module, followed by reuse of the purified water. The digestate also serves as an energy source for the cogeneration unit. The disadvantages of this method are its high capital intensity and implementation complexity. It requires a stable wastewater composition and a precisely balanced energy balance for efficient operation. It does not provide for effective mechanical or flotation treatment prior to the anaerobic stage. It does not address nutrient deficiencies. It does not provide for differentiated treatment of streams with varying levels of contamination. Therefore, it is impractical for a comprehensive and sustainable solution to sugar production wastewater treatment.

An analysis of other literature sources indicates the lack of a method for the effective disposal of sugar production wastewater through biological treatment. This is likely due to the complex composition of this wastewater, the presence of variable pollutant concentrations, and the uneven flow of wastewater due to the seasonal nature of the plants' operations. This complicates the sustainable and efficient operation of anaerobic systems.

The objective of the proposed invention is to develop a method for the treatment and disposal of sugar production wastewater that ensures uniform, stable, and efficient treatment despite significant variability in the qualitative and quantitative composition of the incoming wastewater. The proposed method is aimed at achieving stable and reproducible purified water quality that meets regulatory requirements for such parameters as biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids concentration, as well as nitrogen compounds (including ammonium and nitrate nitrogen) and phosphorus.

Furthermore, the sugar production wastewater disposal method, which involves sequentially organized wastewater treatment stages, reduces the load on subsequent aerobic biological treatment stages during the first stage of anaerobic biological treatment. This, in turn, is designed to prevent equipment downtime during the off-season and ensure rapid startup of the aerobic facilities, thereby increasing the overall energy efficiency of the treatment facility complex and reducing operating costs. Another important objective is to optimize the dewatering and drying processes of the sludge generated during the treatment process, which reduces its volume and moisture content and facilitates subsequent disposal or use of the sludge. During the off-season, to provide the aerobic sludge with substrate, the aeration tank can be fed with dispersed granular activated sludge from the anaerobic UASB reactor to preserve the microbial potential and prevent degradation of the aerobic biocenosis.

One of the key aspects of the proposed method is the production of biogas in an anaerobic reactor, which can be used as an energy source for the technological needs of treatment facilities, thereby reducing the overall energy dependence and environmental impact of production.

The method is adapted to work under conditions of uneven wastewater inflow, which is typical for sugar production, and ensures the stability of the technological process and the reliability of obtaining purified wastewater with changing parameters of the incoming water.

The technical result of the claimed invention is the implementation of a specific sequence of purification stages that create the best conditions for the effective removal of organic matter, biotransformation of biogenic elements and mechanical impurities in wastewater from sugar production, which ensures high stability and reliability of the technological process with fluctuations in the quality and volume of incoming wastewater.

Implementation of the stated sequence of purification stages allows maintaining the standard indicators of purified water (BOD, COD, suspended solids, nitrogen and phosphorus compounds) at a constant level, regardless of external technological and hydrological conditions, ensuring the environmental safety of production and reducing operating costs.

The technical result is achieved by the fact that, depending on the type of wastewater and its specific contaminants, pre-treatment of each stream is provided, wherein industrial wastewater concentrated in organic substances (diffusion juice, pulp press water) is first fed to the averaging tank 1, from where it is then fed to the preliminary mechanical and/or physicochemical treatment unit for further biological treatment in an anaerobic UASB reactor with the following indicators: suspended solids concentration of no more than 200 mg/l, COD from 1,500 to 20,000 mgO ₂ /l; BOD ₅ from 500 to 10,000 mgO ₂ /l; Ca ²⁺ concentration up to 100 mg/l, pH from 6.7 to 8.0 mg/l, N-NH ₄ ⁺ concentration no more than 1000 mg/l, the ratio of organic matter (according to BOD ₅ ) to biogenic substances BOD ₅ : N : P should be at least 100 : 1.0 ÷ 1.5 : 0.2 ÷ 0.3. Such indicators allow to create the optimal operating mode of the anaerobic UASB reactor. Achieving these indicators is possible using available mechanical and physicochemical methods of pre-treatment of highly concentrated wastewater. Then the wastewater is fed to the heat exchanger to heat the wastewater to a temperature of 28 ÷ 39 °C, which is necessary to optimize the operation of the anaerobic UASB reactor. The heat exchanger operates on the principle of heat transfer from the coolant circulating through the internal or external tubes to the wastewater without mixing. Heated wastewater is pumped through a pre-oxidation tank into an anaerobic UASB reactor with a suspended sludge bed and a conditioning column designed for sludge recirculation. The anaerobic UASB reactor consists of a closed cylindrical steel tank with a flat bottom. The upper portion of the tank contains three-phase separation devices (separators in which a lamellar structure first separates the biogas and then retains the anaerobic activated sludge). An external recirculation pipe returns the anaerobic activated sludge to the high-performance zone via high-pressure dry pumps. The biogas generated during anaerobic digestion is collected in a gas holder, which maintains constant gas pressure and prevents its leakage into the atmosphere. From there, it is sent through a pipeline with a system of safety valves to a flare stack for disposal. The residence time in the anaerobic UASB reactor depends on the concentration of organic matter in wastewater and ranges from 4 to 48 hours, the efficiency of reducing organic pollutants by COD ranges from 75% to 90%, _BOD5 from 85% to 95%, the increase in activated anaerobic sludge ranges from 0.02-0.1 g/g of removed COD, then the wastewater from the anaerobic UASB reactor is sent in a pressure mode to separate the suspended portion of the removed activated anaerobic sludge into a settling-type structure (flotator, settling tank). Clarified wastewater from the settling facilities is diverted to equalizer 2, equipped with a mixer and aeration system. This system also receives a slightly contaminated stream (including barometric water condensates with a COD of less than 1000 mg/L), which has previously passed through equalizer 3 and a mechanical treatment unit, where solids larger than 1.0-2.0 mm are removed, as well as mechanically treated domestic wastewater. Both streams are pumped into a sectional aeration tank equipped with a mixer and aeration system. The dissolved oxygen concentration is maintained at no less than 2 mg/L, and the activated sludge dosage is maintained between 5 and 10 g/L of dry matter. The sludge mixture from the sectional aeration tank is then gravity-fed to a membrane reactor with an aeration stirrer, where it is fed to membrane sludge separation modules operating in ultrafiltration mode at a transmembrane pressure of 0.05 MPa using the "outside-in" principle. Dry-run pumps return activated sludge to the aeration tank from the membrane reactor. The biologically treated and filtered wastewater is then sent to an intermediate tank, from where it is fed to an ultraviolet disinfection unit and discharged into a reservoir or diverted for plant technical needs. Flotation sludge resulting from water treatment during the physicochemical treatment stage, excess activated sludge from the membrane sludge separation module block, and sludge from the settling facility are pumped to a sludge storage tank equipped with a stirrer system, from where it is then sent to a sludge dewaterer for dewatering to a moisture content of 75-85%. The dewatering process can be accomplished using various types of equipment, including screw dehydrators or decanter units. The dewatering system operates as follows: sludge is pumped with a controlled flow rate into a contact chamber, where it is mixed with a flocculant solution, which alters the structure of the solid phase of the sludge, increasing its water yield. The prepared sludge is then sent to mechanical dewatering equipment, where separation into solid and liquid phases occurs. In the case of a screw dehydrator, separation is achieved by the rotating screw, while in the case of a decanter unit, centrifugal force is used. The centrate separated during dewatering is discharged into equalizer 1, and the dewatered sludge is unloaded into a container for subsequent transportation to the disposal site. The station's storage facilities are emptied into equalizer 1. Air for the station's needs is supplied by an air blower. The station shall be equipped with a reagent system, including: a unit for preparing and dosing an alkaline solution for calcium precipitation, a unit for preparing and dosing a coagulant solution, a unit for preparing and dosing a flocculant solution, a unit for preparing and dosing an alkaline solution for flotation and washing membrane sludge separation modules, a unit for preparing and dosing a foam suppressor solution, a unit for preparing and dosing a solution for biogenic nitrogen replenishment, a unit for preparing and dosing a solution for biogenic phosphorus replenishment, a unit for preparing and dosing an acid solution, a unit for preparing and dosing an alkaline solution for an aeration tank, a unit for preparing and dosing a sodium hypochlorite solution, a unit for preparing and dosing a flocculant solution for dewatering, a unit for preparing and dosing an acid solution for acidifying granular activated sludge.

The achievement of technical results is also enhanced by equipping one or more sections of the aeration tank with brush media. This ensures the preservation and stable functioning of aerobic biomass during periods of downtime for the primary production process, when the supply of highly contaminated wastewater to the aeration tank is limited or completely stopped, allowing the system to operate during the off-season. The attached biomass, forming a structural matrix of polymer networks, creates localized zones with increased nutrient concentrations. This allows microorganisms to maintain metabolic activity for a long time, even in the absence of external substrate supply. Upon resumption of operation after the off-season, this system ensures rapid restoration and proliferation of the microbial community. At the same time, during periods of low loads, the concentration of dissolved oxygen in these sections is maintained at a level of 3-5 mg/l and the dose of activated sludge within 1-2 g/l, which ensures the preservation and stable functioning of aerobic biomass, allows for the system to function during the off-season and, upon reaching full seasonal load, quickly restore the working concentration of biomass.

The achievement of technical results is also affected by the fact that during periods of downtime in the main production process, when small quantities of contaminated wastewater are received for treatment, the sections with brush media in the aeration tank are left in operation. During this period, equalizer 2 is fed with domestic wastewater, possibly also surface runoff, and other water reserves. Anaerobic sludge dispersed by cavitation is also supplied from the granulated activated sludge storage tank, which previously accumulates granulated sludge from the anaerobic UASB reactor and/or settling facility. Before being fed to equalizer 2, it is pre-dispersed using cavitation. Cavitation mechanically disrupts the bacterial cell walls in the sludge, releasing bioavailable organic matter and nutrients. The optimal sludge moisture content is 96%. The substrate is diluted with water and adjusted to a pH of 6.5-8.0, optimal for activating the enzymatic activity of microorganisms, after which it is fed to the aeration tank. This solution prevents starvation and death of the microbial communities in the aeration tank's activated sludge in the absence of contaminants, ensuring the stability and effectiveness of subsequent biological treatment.

The achievement of technical results is also affected by the fact that wastewater with a calcium concentration above 100 mg/L is alkalized in an intermediate tank to a pH of 9-10 units, forming a sediment. It is advisable to use soda or lime as reagents. The sediment is removed by flotation, after which an acidic reagent is dosed into the pre-oxidation tank to reduce the pH to 7.5-8.5, which ensures optimal conditions for the subsequent delivery of purified water to the anaerobic UASB reactor.

The achievement of technical results is also influenced by the fact that, if necessary, provision is made for the possibility of feeding a slightly contaminated flow into the pre-oxidation tank for mixing with a highly contaminated flow, which ensures a reduction in energy costs for heating due to the heat content of the slightly contaminated flow and a reduction in the amount of dosed biogenic nitrogen feed due to the nitrogen-containing organic compounds contained in the flow in sufficient quantities.

The dewatered sludge is also fed into a paddle-type dryer, where it is mixed and heated, reducing its residual moisture content to 20%. The resulting vapors are removed through an opening in the dryer lid and fed to a two-stage cleaning system: first, to a cyclone separator to capture solid particles, then to a wet scrubber for final purification of the gas-air mixture. The resulting contaminated water is discharged into equalizer 1. The dried sludge is discharged into a sludge container and transported to a landfill. Mineral oil is used as a heat transfer agent during the drying process.

The achievement of technical results is also influenced by the fact that the biogas accumulated in the gas holder is sent to a biogas purification system and then fed to a gas boiler to generate thermal energy. The generated heat is then used to heat the heating water, which acts as a coolant in the heat exchanger, which ensures a closed energy cycle and compensation for energy costs due to the use of the plant's own power generating unit.

Thus, the proposed method for purification and disposal of wastewater from sugar production is logically justified, is unified and confirmed by experimental data.

In accordance with the above and taking into account the disclosed cause-and-effect relationship between the set of features of the claimed invention and the technical results achieved, it can be stated that the problem set as the basis for creating a method for biological treatment of wastewater from sugar production has been fully solved, since the use of the invention, due to a logically justified sequence of treatment stages, makes it possible to achieve a technical result consisting in the implementation of a certain sequence of treatment stages that create the best conditions for effective sequential anaerobic and aerobic processing of organic pollutants with a maximum yield of biogas, a decrease in the concentration of suspended matter and dissolved organic matter due to preliminary mechanical and physicochemical preparation, subsequent biological destruction of polluting compounds in an anaerobic reactor and deep post-treatment in the aerobic and membrane stages, which ensures the stability of the operation of the treatment system even with a sharp change in the composition, temperature and volume of incoming wastewater from sugar production.

Fig. 1 shows a flow chart of the method for cleaning and utilizing wastewater from sugar factories, in accordance with the claims of the invention.

1. Averager 1;

2. Facilities for mechanical and/or physical-chemical wastewater treatment;

3. Alkalization tank;

4. Mechanical stirrer;

5. Physical and chemical softening unit (flotator);

6. Heat exchanger for heating wastewater;

7. Pre-oxidation tank;

8. Anaerobic UASB reactor;

9. Gas holder;

10. Torch candle;

11. Sedimentation structure;

12. Averager 2;

13. Aeration system;

14. Aeration tank;

15. Membrane reactor;

16. Membrane sludge separation modules;

17. Ultrafiltrate tank;

18. Ultraviolet disinfection unit;

19. Storage tank for granulated activated sludge;

20. Averager 3;

21. Mechanical cleaning unit for slightly contaminated flow;

22. Sediment storage tank;

23. Sludge dewatering facility;

24. Paddle type dryer;

25. Air blower;

26. Unit for preparing and dosing alkaline solution for calcium precipitation;

27. Unit for preparation and dosing of coagulant solution;

28. Unit for preparation and dosing of flocculant solution;

29. Unit for preparation and dosing of alkaline solution for flotation and washing of membrane sludge separation modules;

30. Unit for preparation and dosing of antifoam solution;

31. Unit for preparation and dosing of biogenic nitrogen feed solution;

32. Unit for preparation and dosing of biogenic phosphorus feed solution;

33. Unit for preparing and dosing acid solution for acidifying water before the anaerobic UASB reactor;

34. Unit for preparation and dosing of alkaline solution for aeration tank;

35. Unit for preparing and dosing acid solution for washing membrane sludge separation modules;

36. Unit for preparing and dosing sodium hypochlorite solution for washing membrane sludge separation modules;

37. Unit for preparation and dosing of flocculant solution for dehydration;

38. Unit for preparation and dosing of acid solution for acidification of granular activated sludge;

39. Biogas purification system;

40. Gas boiler.

Pipelines:

P1. - Pipeline for supplying alkaline solution for calcium precipitation;

P2. - Pipeline for feeding coagulant solution for flotation;

P3. - Pipeline for feeding flocculant solution for flotation;

P4. - Pipelines for feeding alkaline solution for flotation;

P5. - Pipeline for supplying defoamer solution;

P6. - Pipeline for feeding the biogenic nitrogen make-up solution to the pre-oxidation tank;

P7. - Pipeline for feeding the biogenic phosphorus feed solution into the pre-oxidation tank;

P8. - Pipeline for feeding acid solution into the pre-oxidation tank;

P9. - Pipeline for feeding the solution of biogenic nitrogen feed to the aeration tank;

P10. - Pipeline for feeding the biogenic phosphorus feed solution to the aeration tank;

P11. - Pipelines for supplying alkaline solution to the aeration tank;

P12. - Pipelines for supplying alkaline solution for washing membrane sludge separation modules;

P13. - Pipelines for supplying acid solution for washing membrane sludge separation modules;

P14. - Pipeline for supplying sodium hypochlorite solution for washing membrane sludge separation modules;

P15. - Pipeline for feeding flocculant solution for dehydration;

P16. - Pipeline for supplying acid solution for acidifying granular activated sludge.

The purification method is carried out as follows: heavily polluted wastewater after pre-purification (mechanical purification) is fed to the equalizer 1 (1), the following flows can also be sent to the equalizer 1 (1), if they are available: polluted water from the biogas purification system (39), centrate formed as a result of the operation of the sludge dewatering facility (23), polluted wastewater from the wet cleaning system (scrubber) of the exhaust gases of the paddle-type drying unit (24), purified wastewater from the storage facilities during their inspection and emptying.

From the equalizing tank 1 (1), the averaged wastewater is sent to the physicochemical treatment and softening unit of wastewater, which is equipped with mechanical and/or physicochemical treatment facilities (2) to reduce the concentration of suspended and organic matter, an alkalization tank (3) with a mechanical mixer (4), and a physicochemical softening unit (flotator) (5). Wastewater with a calcium concentration above 100 mg/l is alkalized in the alkalization tank (3) to a pH of 9÷10 units with the formation of a sediment, which is removed by flotation treatment in the structure of the physicochemical softening unit (flotator) (5). For this purpose, the necessary reagents are dosed into the alkalization tank (3) and into the physicochemical softening unit (flotator) (5) in the following order: - alkaline solution for calcium precipitation from the unit for preparing and dosing the alkaline solution for calcium precipitation (26) through pipeline (P1) into the alkalization tank (3); - coagulant from the unit for preparing and dosing the coagulant (27) through pipeline (P2) into the physicochemical softening unit (flotator) (5); - flocculant from the unit for preparing and dosing the flocculant (28) through pipeline (P3) into the physicochemical softening unit (flotator) (5); - alkaline solution for flotation from the unit for preparing and dosing the alkaline solution for flotation and washing the membrane sludge separation modules (29) through pipeline (P4) into the physicochemical softening unit (flotator) (5); - solution defoamer from the defoamer solution preparation and dosing unit (30) through the pipeline (P5) to the physicochemical softening unit (flotator) (5). Softened wastewater with pollutant concentrations according to the following indicators: suspended solids concentration no more than 200 mg/l, COD from 1,500 to 20,000 _mgO2 /l; BOD5 from 500 to 10,000 _mgO2 /l; Ca2 ⁺ concentration up to 100 mg/l, pH from 6.7 to 8.0 mg/l, N-NH4 concentration no more than 1,000 mg/l, the ratio of organic matter (according to BOD5) to biogenic substances BOD5: N: P should be at least 100: 1.0-1.5: 0.2-0.3. Next, the wastewater is fed to the wastewater heating heat exchanger (6), through which the coolant heated in the gas boiler (40) circulates. Provision is also made for heating the coolant from an external heat source. Heated wastewater is fed to the pre-oxidation tank (7), equipped with a mechanical mixer (4), into which reagents for biogenic make-up are introduced through pipelines (P6 and P7), as well as an acid solution through pipeline (P8) to optimize the pH in the anaerobic UASB reactor (8). Provision is made for feeding slightly contaminated wastewater from the mechanical treatment unit for slightly contaminated flow (21) to the pre-oxidation tank (7). After treatment, the wastewater from the pre-oxidation tank (7) is fed to the anaerobic UASB reactor (8) with a suspended sludge layer and a conditioning column designed for sludge recirculation. From the external recirculation pipe, the anaerobic activated sludge is returned to the high-performance zone by high-pressure dry pumps. The biogas generated during the process is accumulated in a gas holder (9) and from there sent to a flare stack (10) for disposal. An alternative, distinctive option involves the purification and use of the biogas accumulated in the gas holder. According to this option, the accumulated gas is sent to a biogas purification system (39) and then fed to a gas boiler (40) for thermal energy generation. The generated heat is used to heat the heating water, which serves as the coolant in the wastewater heating heat exchanger (6). From the anaerobic UASB reactor (8), the purified wastewater is sent under pressure to separate the suspended portion of the carried-out activated sludge into a settling structure (11); from the settling structure (11), the clarified wastewater is diverted to an equalizer 2 (12) equipped with a mechanical mixer (4) and an aeration system (13), into which a slightly contaminated flow (including condensates of barometric waters with a COD of less than 1000 mg/l) is also sent, having previously passed through an equalizer 3 (20) and a mechanical treatment unit for a slightly contaminated flow (21), where solid inclusions larger than 1.0-2.0 mm are removed. Mechanically treated domestic wastewater is also sent to an equalizer 2 (12). During periods of downtime of the main production, anaerobic sludge dispersed by the cavitation method is fed to the equalizing tank 2 (12) from the granular activated sludge storage tank (19). At the same time, the acid reagent from the acid solution preparation and dosing unit for acidifying the granular activated sludge (38) is dosed through the pipeline (P16) into the granular activated sludge storage tank (19). From the equalizing tank 2 (12), the wastewater is fed by pumps to the sectional aeration tank (14), equipped with a mechanical mixer (4) and an aeration system (13). The reagents are dosed into the sectional aeration tank (14) in the following order: - a solution of biogenic nitrogen feed from the unit for preparing and dosing the solution of biogenic nitrogen feed (31) through the pipeline (P9) into the aeration tank (14); - a solution of biogenic phosphorus feed from the unit for preparing and dosing the solution of biogenic phosphorus feed (32) through the pipeline (P10) into the aeration tank (14); - an alkaline solution from the unit for preparing and dosing the alkaline solution for the aeration tank (34) through the pipeline (P11) into the aeration tank (14). Then the sludge mixture from the sectional aeration tank (14) is directed in the gravity mode to the membrane reactor (15) with the aeration system (13), where it is fed to the membrane sludge separation modules (16), while the activated sludge is returned to the sectional aeration tank (14) from the membrane reactor (15) using dry-type pumps. The necessary reagents are dosed into the pipeline providing washing of the membrane sludge separation modules (16) in the following order: - alkaline solution for washing the membrane sludge separation modules from the unit for preparing and dosing alkaline solution for flotation and washing of the membrane sludge separation modules (29) through pipeline (P12) into the pipeline for washing the membrane sludge separation modules (16); - acidic solution from the unit for preparing and dosing acidic solution for washing the membrane sludge separation modules (35) through pipeline (P13) into the pipeline for washing the membrane sludge separation modules (16); - sodium hypochlorite solution from the unit for preparing and dosing sodium hypochlorite solution for washing the membrane sludge separation modules (36) through pipeline (P14) into the pipeline for washing the membrane sludge separation modules (16).

Next, the biologically purified and filtered wastewater is sent to an intermediate ultrafiltrate tank (17), from where it is fed to an ultraviolet disinfection unit (18) and discharged into a reservoir or diverted for the technical needs of the station.

Flotation sludge generated as a result of water treatment in the physicochemical softening facility (flotator) (5) of wastewater, excess activated sludge from the block of membrane sludge separation modules (16), as well as sludge from the settling-type facility (11) are pumped into the sludge storage tank (22) equipped with an aeration system (13), from where it is then sent to the sludge dewatering facility (23) for its dewatering to a moisture content of 75-85%. Before dewatering, a flocculant solution is dosed to increase the water yield of the sludge. Flocculant from the unit from the flocculant solution preparation and dosing unit for dewatering (37) is dosed through the pipeline (P15) before the sludge dewatering facility (23). The centrate separated during dewatering is discharged into equalizer 1 (1), and the dewatered sludge can be transported to a disposal site or sent to a paddle dryer (24). The dried sludge is unloaded into a sludge container and transported to a landfill. The resulting vapors are treated using a wet scrubber, and the resulting, contaminated water is discharged into equalizer 1 (1). Air for the station's needs is supplied by an air blower (25).

Fig. 2 shows a flow chart of an example of the implementation of a method for cleaning and disposing of wastewater from sugar factories.

Legend:

3. Alkalization tank;

4. Mechanical stirrer;

5. Physical and chemical softening unit (flotator);

6. Heat exchanger for heating wastewater;

7. Pre-oxidation tank;

8. Anaerobic UASB reactor;

9. Gas holder;

10. Torch candle;

11. Sedimentation structure;

13. Aeration system;

14. Aeration tank;

15. Membrane reactor;

16. Membrane sludge separation modules;

17. Ultrafiltrate tank;

18. Ultraviolet disinfection unit;

19. Storage tank for granulated activated sludge;

22. Sediment storage tank;

23. Sludge dewatering facility;

25. Air blower;

26. Unit for preparing and dosing alkaline solution for calcium precipitation;

27. Unit for preparation and dosing of coagulant solution;

28. Unit for preparation and dosing of flocculant solution;

29. Unit for preparation and dosing of alkaline solution for flotation and washing of membrane sludge separation modules;

30. Unit for preparation and dosing of antifoam solution;

31. Unit for preparation and dosing of biogenic nitrogen feed solution;

32. Unit for preparation and dosing of biogenic phosphorus feed solution;

33. Unit for preparing and dosing acid solution for acidifying water before the anaerobic UASB reactor;

34. Unit for preparation and dosing of alkaline solution for aeration tank;

35. Unit for preparing and dosing acid solution for washing membrane sludge separation modules;

36. Unit for preparing and dosing sodium hypochlorite solution for washing membrane sludge separation modules;

37. Unit for preparation and dosing of flocculant solution for dehydration;

38. Unit for preparing and dosing acid solution for acidifying granulated activated sludge.

39. Biogas purification system;

40. Gas boiler;

41. Settling pond for heavily polluted stream;

42. Rough mechanical cleaning of heavily polluted flow;

43. Fine mechanical cleaning of heavily polluted flow;

44. Intermediate tank for mechanically and physically-chemically purified highly polluted flow;

45. Heat exchanger for preheating wastewater;

46. Intermediate tank for clarified water;

47. Macerator;

48. Sewage pumping station;

49. Settling pond for slightly polluted stream;

50. Rough mechanical cleaning of slightly contaminated flow;

51. Fine mechanical cleaning of slightly contaminated flow;

52. Intermediate tank for mechanically cleaned slightly polluted flow;

Pipelines:

P1. - Pipeline for supplying alkaline solution for calcium precipitation;

P2. - Pipeline for feeding coagulant solution for flotation;

P3. - Pipeline for feeding flocculant solution for flotation;

P4. - Pipelines for feeding alkaline solution for flotation;

P5. - Pipeline for supplying defoamer solution;

P6. - Pipeline for feeding the biogenic nitrogen make-up solution to the pre-oxidation tank;

P7. - Pipeline for feeding the biogenic phosphorus feed solution into the pre-oxidation tank;

P8. - Pipeline for feeding acid solution into the pre-oxidation tank;

P9. - Pipeline for feeding the solution of biogenic nitrogen feed to the aeration tank;

P10. - Pipeline for feeding the biogenic phosphorus feed solution to the aeration tank;

P11. - Pipelines for supplying alkaline solution to the aeration tank;

P12. - Pipelines for supplying alkaline solution for washing membrane sludge separation modules;

P13. - Pipelines for supplying acid solution for washing membrane sludge separation modules;

P14. - Pipeline for supplying sodium hypochlorite solution for washing membrane sludge separation modules;

P15. - Pipeline for feeding flocculant solution for dehydration;

P16. - Pipeline for supplying acid solution for acidifying granular activated sludge.

The purification method is carried out as follows: wastewater from sugar production, generated as a result of the operation of sugar beet processing and forming 2 streams, one of which is heavily polluted (water from washing sugar beets after sedimentation / from the settling tank) and demonstrates the following main indicators: the concentration of suspended solids is 200 mg / l, BOD - 6000 mgO ₂ / l, COD - 10000 mgO ₂ / l, total phosphorus - 10 mg / l, total nitrogen - 110 mg / l, calcium - 600 mg / l, pH - 5-11 units, and the second is slightly polluted (excess condensate) and has the following values of the same indicators: the concentration of suspended solids is 30 mg / l, BOD - 150 mgO ₂ / l, COD - 250 mgO ₂ / l, total phosphorus - 2 mg / l, total nitrogen - 120 mg/l, calcium - 0 mg/l, pH - 6.5-9 units, fed to the WWTP site for further treatment. Heavily polluted flow is directed to the settling pond of the heavily polluted flow (41) for temporary accumulation of wastewater and sedimentation of mechanical impurities. The following flows, if available, can also be directed to the settling pond of the heavily polluted flow (41): contaminated water from the biogas purification system (39), centrate generated as a result of the sludge dewatering facility (23), treated wastewater from storage facilities during their inspection and emptying. From the settling pond of the heavily polluted flow (41), water is fed by a pumping group to the stage of rough mechanical treatment of the heavily polluted flow (42), where suspended particles larger than 6.0 mm are retained, which ensures protection of the subsequent treatment stages. The flow is then fed into an alkalization tank (3) equipped with a mechanical mixer (4), where wastewater with a calcium concentration of 600 mg/l is alkalized through a pipeline (P1) with an alkaline solution of sodium carbonate to a pH of 9-10 units, forming a sediment that is removed by flotation treatment. The necessary reagents are dosed into the alkalization tank (3) and the flocculator of the reagent flotation unit of the physicochemical softening unit (5) in the following order: - an alkaline solution of sodium carbonate from the unit for preparing and dosing the alkaline solution for calcium precipitation (26) through the pipeline (P1) into the alkalization tank (3); - a coagulant from the unit for preparing and dosing the coagulant (27) through the pipeline (P2) into the flocculator of the reagent flotation unit of the physicochemical softening unit (5); - a flocculant from the unit for preparing and dosing the flocculant (28) through the pipeline (P3) into the flocculator of the reagent flotation unit of the physicochemical softening unit (5); - an alkaline solution of sodium hydroxide from the unit for preparing and dosing the alkaline solution for flotation and washing the membrane sludge separation modules (29) through the pipeline (P4) into the flocculator of the reagent flotation unit of the physicochemical softening unit softening (5); - defoamer solution from the defoamer solution preparation and dosing unit (30) through the pipeline (P5) to the flocculator of the reagent flotation unit of the physicochemical softening block (5).

The pumping group transports the flow to the reagent flotation unit of the physicochemical softening unit (5) with an efficiency for suspended solids of 85%, designed to maximize the collection of suspended solids and reduce the load on the anaerobic UASB reactor (8) with a conditioning column. From the flotation unit (5), the wastewater is fed to the fine mechanical cleaning stage of the highly contaminated flow (43) to remove suspended particles smaller than 1.0 mm. The water is then fed to the intermediate tank for mechanically and physicochemically purified highly contaminated flow (44), from where the pumping group feeds it to the wastewater preheating heat exchanger (45), the coolant of which is heated by a gas boiler (40) processing biogas. The water is then sent to a wastewater heating heat exchanger (6) to heat the water to a temperature of 36 degrees Celsius using a coolant supplied by an external heat source, ensuring optimal temperature conditions for the efficient operation of the anaerobic UASB reactor (8). The heated wastewater is sent to a pre-oxidation tank (7), equipped with a mechanical mixer (4). The necessary reagents are dosed into the pre-oxidation tank (7) in the following order: - a solution of biogenic nitrogen feed from the unit for preparing and dosing the solution of biogenic nitrogen feed (31) through pipeline (P6) into the pre-oxidation tank (7); - a solution of biogenic phosphorus feed from the unit for preparing and dosing the solution of biogenic phosphorus feed (32) through pipeline (P7) into the pre-oxidation tank (7); - a solution of sulfuric acid from the unit for preparing and dosing the acid solution for acidifying water in front of the anaerobic UASB reactor (33) through pipeline (P8) into the pre-oxidation tank (7). Dosing of biogenic nitrogen feed and biogenic phosphorus feed is carried out to eliminate the deficiency of phosphorus and nitrogen based on the calculation of the BOD: Nitrogen: Phosphorus ratio of 350:5:1, which is optimal for the anaerobic UASB reactor (8). The dosing of an acid reagent - a solution of sulfuric acid - is carried out to reduce the pH to 7.5-8, which provides optimal conditions for the subsequent supply of purified water to the anaerobic UASB reactor (8).

The heated wastewater is pumped into two anaerobic UASB reactors (8), each with a capacity of 900 ^m³ , containing a suspended sludge layer and a conditioning column for sludge recirculation. The anaerobic UASB reactor (8) consists of a closed cylindrical steel tank with a flat bottom. The upper part of the tank contains three-phase separation devices (separators in which a lamellar structure first separates the biogas and then retains the anaerobic activated sludge). An external recirculation pipe returns the anaerobic activated sludge to the high-performance zone using high-pressure dry pumps. Wastewater from the anaerobic UASB reactor (8) is then directed under pressure to separate the suspended portion of the discharged anaerobic activated sludge in a settling structure (11). The clarified wastewater is fed through an intermediate clarified water tank (46) into an aeration tank (14), equipped with a mechanical mixer (4) and an aeration system (13), where aerobic-anaerobic biological treatment of the wastewater occurs. The dissolved oxygen concentration is maintained at 2 mg/L, and the activated sludge dose is maintained at 5 g/L of dry matter. The necessary reagents are dosed into the aeration tank (14) in the following order: - a solution of biogenic nitrogen feed from the unit for preparing and dosing the solution of biogenic nitrogen feed (31) through the pipeline (P9) into the aeration tank (14); - a solution of biogenic phosphorus feed from the unit for preparing and dosing the solution of biogenic phosphorus feed (32) through the pipeline (P10) into the aeration tank (14); - a solution of soda from the unit for preparing and dosing the alkaline solution for the aeration tank (34) through the pipeline (P11) into the aeration tank (14), wherein the said reagents provide the necessary conditions for the vital activity of microorganisms and the neutralization of the acidity of wastewater and the maintenance of an optimal pH value. In the aeration tank, the heavily polluted stream is mixed with the lightly polluted stream (49) that has previously passed through a settling pond and the lightly polluted stream, mechanically purified at the stages of coarse mechanical purification of the lightly polluted stream (50) and fine mechanical purification of the lightly polluted stream (51). The lightly polluted stream contains nitrogen in sufficient quantity, which minimizes or eliminates the need for additional dosing of biogenic nitrogen feed. Thanks to mechanical purification, solids larger than 1.0 mm are removed from the water, which ensures a safe and stable water supply to the membrane reactor (15). The lightly polluted stream is fed into the aeration tank through an intermediate reservoir for mechanically purified lightly polluted stream (52) by means of a pump group. During downtime, when the highly contaminated flow is not being fed, if necessary, a slightly contaminated flow, mechanically treated, is fed to the wastewater heating heat exchanger (6) to heat it before further processing. To ensure the return of activated sludge, it is recycled to the aeration tank (14) from the membrane reactor (15) using a pump group.

Then the sludge mixture from the aeration tank (14) is directed under gravity to the membrane reactor (15) with an aeration stirrer (13), where it is fed to the membrane sludge separation unit (16), which operates in the ultrafiltration mode at a transmembrane pressure of 0.05 MPa according to the "outside-in" principle, while the activated sludge is returned to the aeration tank from the membrane reactor using dry-type pumps. The necessary reagents are dosed into the pipeline providing washing of the membrane sludge separation modules (16) in the following order: - sodium hydroxide solution for washing the membrane sludge separation modules from the alkaline solution preparation and dosing unit for flotation and washing of the membrane sludge separation modules; (29) via pipeline (P12) to the membrane sludge separation module flushing pipeline (16); - hydrochloric acid solution from the acid solution preparation and dosing unit for flushing the membrane sludge separation modules; (35) via pipeline (P13) to the membrane sludge separation module flushing pipeline (16); - sodium hypochlorite solution from the sodium hypochlorite solution preparation and dosing unit for flushing the membrane sludge separation modules (36) via pipeline (P14) to the membrane sludge separation module flushing pipeline (16).

Next, the biologically purified and filtered wastewater is sent to the ultrafiltrate tank (17), from where it is fed by a pump group to the ultraviolet disinfection unit (18) and discharged into a reservoir or diverted for the technical needs of the station.

Flotation sludge generated as a result of water treatment in the reagent flotation unit of the physicochemical softening block (5), anaerobic activated sludge from the membrane sludge separation modules (16), and excess granulated activated sludge from the granulated activated sludge storage tank (19) are fed to the sludge storage tank (22) equipped with an aeration system (13), from where it is then fed by a pump group to the sludge dewatering structure (23) - a decanter centrifuge, where the sludge is dewatered to a moisture content of 80%. The centrate separated during the dewatering process is discharged through the sewage pumping station (48) into the settling pond of a heavily polluted stream (41), and the dewatered sludge is unloaded into a container for subsequent transportation to the disposal site. Before dewatering, a flocculant solution is dosed to increase the water yield of the sediment. Flocculant from the flocculant solution preparation and dosing unit for dewatering (37) is dosed through pipeline (P15) before the sludge dewatering unit (23). The waste separated from the mechanical cleaning stages is compressed and sent to waste tanks, after which it is transported to the landfill.

The biogas obtained from the anaerobic UASB reactor (8) is accumulated in a gas holder (9) and from there sent to a flare stack (10) for utilization or sent to a biogas purification system (39) with subsequent feeding to a gas boiler (40) for thermal energy generation. The generated heat is used to heat the heating water, which acts as a coolant in the wastewater preheating heat exchanger (45), which ensures a closed energy cycle and compensation of energy costs due to the use of an in-house power generating unit. Anaerobic UASB reactors provide a total wastewater residence time of approximately 12 hours, the efficiency of reducing organic pollutants by COD is 80%, BOD5 85%, the increase in activated anaerobic sludge amounts to 0.02 g/g of removed COD.

During periods of downtime in the main production process, when only a slightly contaminated stream is fed into the system, granular activated sludge from the anaerobic UASB reactor (8) and the settling structure (11) is pre-accumulated in a granular activated sludge storage tank (19) and then discharged by a screw pump to the aeration tank (14) to maintain the vital activity of the activated sludge in the biological treatment system. This provides a substitute for traditional reagent biological feed. The rest of the time, granular activated sludge is fed for dewatering. Before feeding to the aeration tank (14), the granular activated sludge is pre-dispersed using a macerator (47), diluted with water, and its pH adjusted to a value of 6.5-8.0 units, optimal for activating the enzymatic activity of microorganisms. The acid reagent from the acid solution preparation and dosing unit for acidifying granular activated sludge (38) is dosed through pipeline (P16) into the granular activated sludge storage tank (19). This solution prevents starvation and death of the microbial communities in the aeration tank's activated sludge in the absence of pollutants, ensuring the stability and effectiveness of subsequent biological treatment. During inspections of the station's storage facilities, they are emptied into the heavily polluted flow settling pond (41). Air for the station's needs is supplied by an air blower (25).

To determine the design parameters for implementing a method for sugar production wastewater disposal, laboratory studies were conducted at pilot facilities using a simulated sugar production wastewater solution with typical industry pollutant concentrations. Concentrations of the main pollutants by treatment stage are presented in Table 1.

Table 1 - Results of monitoring the main pollutants of sugar production wastewater at the processing stages

Basic water indicators Units of measurement Raw wastewater After mechanical and physical-chemical cleaning After anaerobic treatment (UASB reactor) After the secondary settling tank After the aerobic reactor Suspended solids mg/l 200 20 5,000 < 100 <3 BPK ₅ mg O ₂ /l 6,500 6 100 600 < 600 <2.1 COD mg O ₂ /l 11 100 10,050 1,000 < 1,000 <30 Temperature °C 35 35 35 35 20 NH ₄ ⁺ mg/l 125 125 < 10 < 10 <0.4 PO ₄ ^3- mg/l 9 < 1 < 1 < 1 <0.1 Ca ²⁺ mg/l 600 94 94 94 94 pH Unit 7.5-8.0 7.5-8.0 7.5-8.0 7.5-8.0 7.5-8.0

A testbed setup was used to conduct the research. The setup includes capacitive units to ensure the required residence time, a feed system for the simulant, and equipment to ensure the specified process conditions.

During the experimental study on anaerobic biological treatment of sugar production wastewater, the following stages were sequentially completed. Initially, sugar production wastewater samples were collected and initial parameters were determined. Preparation for the study included calibrating the measuring equipment and adjusting the process parameters of the pilot plant. To ensure stable experimental conditions, a model solution was prepared that reproduced the typical composition of actual sugar production wastewater.

During the first stage, the wastewater underwent mechanical and physicochemical treatment, removing suspended solids and coarse particles. Following this preparation, the main phase of the research began, conducted in a 10 ^m³ anaerobic UASB reactor with a working liquid layer height of 5 meters. During the research, the maximum permissible loads were determined: hydraulic load of 0.25 ^m³ /hour of water/1 ^m³ of tank per day, and the COD load was 0.02 _gO² /1 ^m³ of tank per day. All parameters were monitored under actual operating conditions without changing the process mode. Measurements were performed using control equipment in accordance with the approved test method.

It has been calculated and experimentally established that the residence time of wastewater in the anaerobic UASB reactor system for a given volume is 4 hours, which provides optimal conditions for the degradation of organic contaminants.

During anaerobic treatment, excess activated sludge increases, amounting to 2 to 4% of the consumed COD, which is important to consider when designing a sludge dewatering system. The optimal COD:N:P ratio has also been established at 350:5:1, necessary for the stable functioning of anaerobic microflora.

Maintaining a pH of 7-8 and a temperature of 28 to 39°C (optimum 36°C) ensures stable anaerobic processes, as confirmed experimentally. The system's buffering capacity also provides protection against acidification for 4-6 hours.

The measured biogas output was approximately 0.4 ^Nm3 per kg of COD consumed, confirming the economic and environmental efficiency of the proposed technology.

Based on the obtained results, the operability of the proposed technological scheme of the method of anaerobic biological treatment of wastewater from sugar production was established, and the technological parameters for the calculation of real structures were determined.

In the next stage, wastewater treated in the UASB reactor was sent to a secondary clarifier, where activated sludge was separated and pollutant concentrations were further reduced. The final stage was aerobic biological treatment, implemented in an aeration tank, which reduced residual concentrations of organic matter, ammonia nitrogen, and phosphates. During the study, all changes in key water quality indicators were recorded, providing a detailed picture of the process's effectiveness.

The final stage included analyzing the obtained data, assessing the treatment efficiency for each parameter, and determining the optimal process parameters for designing industrial wastewater treatment facilities. The experimental results confirmed the viability of the proposed process flow diagram and allowed us to establish the key parameters for calculating actual wastewater treatment facilities.

Claims (7)

1. A method for purifying and utilizing wastewater from a sugar production facility, characterized by the fact that, depending on the type of wastewater and its specific contaminants, pre-treatment of each stream is provided, wherein the industrial wastewater, concentrated in organic matter, is first fed to the first equalizer, from where it is then fed to a preliminary mechanical and/or physicochemical treatment unit for further biological treatment in an anaerobic UASB reactor to achieve the following concentrations according to the following indicators: suspended solids concentration no more than 200 mg/l, COD from 1,500 to 20,000 _mgO2 /l; _BOD5 from 500 to 10,000 _mgO2 /l; concentration of Ca ²⁺ up to 100 mg/l, pH from 6.7 to 8.0 mg/l, concentration of N-NH ₄ no more than 1000 mg/l, the ratio of organic matter by BOD ₅ to biogenic substances BOD₅ : N : P should be at least 100 : 1.0-1.5 : 0.2-0.3, then the wastewater is fed to a heat exchanger to heat the wastewater to a temperature of 28-39 °C, which is necessary to optimize the operation of the anaerobic UASB reactor, the heated wastewater is pumped through a pre-oxidation tank into an anaerobic UASB reactor with a suspended sludge layer and a conditioning column designed for sludge recirculation, the anaerobic UASB reactor consists of a closed cylindrical steel tank with a flat bottom, in the upper part of the tank there are 3-phase separation devices - separators in which the lamellar design first separates the biogas and then retains the anaerobic activated sludge, an external recirculation pipe returns the anaerobic activated sludge to the high-performance zone using high-pressure dry pumps, while the resulting biogas is accumulated in a gas holder and from there sent to a flare stack for disposal, the residence time in the anaerobic UASB reactor depends on the concentration of organic matter in the wastewater and ranges from 4 to 48 hours, the efficiency of reducing organic pollutants by COD ranges from 75% to 90%, _BOD5 from 85% to 95%, the increase in activated anaerobic sludge ranges from 0.02-0.1 g / g of removed COD, then the wastewater from the anaerobic UASB reactor is sent in a pressure mode to separate the suspended portion of the removed activated anaerobic sludge in a settling-type structure, The clarified wastewater from the settling-type structures is diverted to the second equalizing tank equipped with a mixer and an aeration system, into which a slightly polluted flow is also sent, including condensates of barometric waters with a COD of less than 1000 mg / l, previously passed through the third equalizing tank and a mechanical cleaning unit, where solid inclusions larger than 1.0-2.0 mm are removed, mechanically purified domestic wastewater is also sent, from the second equalizing tank, the wastewater is fed by pumps to a sectional aeration tank equipped with a mixer and an aeration system, the concentration of dissolved oxygen in the sectional aeration tank is maintained at least 2 mg / l, the dose of activated sludge is maintained from 5 to 10 g / l of dry matter, then the sludge mixture from the sectional aeration tank is sent in a gravity mode to a membrane reactor with an aeration stirrer, where it is fed to membrane sludge separation modules, which operate in the ultrafiltration mode at a transmembrane pressure of 0.05 MPa according to the "outside-in" principle, while ensuring the return of activated sludge to the aeration tank from the membrane reactor using dry-type pumps, then biologically purified and filtered wastewater is sent to an intermediate tank, from where it is fed to an ultraviolet disinfection unit and discharged into a reservoir or diverted for the technical needs of the station, flotation sludge formed as a result of water treatment at the stage of physicochemical treatment, excess activated sludge of the block of modules of the membrane sludge separation, also sludge from the settling-type structure is fed by pumps to a sludge storage tank equipped with a roiling system, from where it is then sent to a sludge dewaterer for its dewatering to a moisture content of 75-85%, before dewatering, a flocculant solution is dosed to increase the water yield of the sediment, the centrate separated during the dewatering process is diverted to the first equalizer, and the dewatered sludge is discharged into container for subsequent transportation to the disposal site; during the inspection of the station's tank structures, they are emptied into the first equalizer; air is supplied for the station's needs using an air blower; the station is equipped with a reagent system to ensure the required cleaning efficiency. 2. The method according to paragraph 1, characterized in that one or more sections of the aeration tank are equipped with a brush load, which ensures the preservation and stable functioning of the aerobic biomass during periods of downtime of the main production, during which the supply of wastewater to the aeration tank can be completely stopped and the functioning of the system can be maintained, and also when reaching full load - quickly restore the working concentration of the biomass, while in order to preserve and ensure the stable functioning of the aerobic biomass in these sections, the concentration of dissolved oxygen is maintained at a level of 3-5 mg / l and the dose of activated sludge is within 1-2 g / l. 3. The method according to paragraph 1, characterized in that during periods of downtime of the main production, sections with brush loading are left in operation in the aeration tank, while domestic wastewater, possibly also surface runoff and other water reserves, are fed into the second equalizer during this period, anaerobic sludge dispersed by the cavitation method is also fed from the granular activated sludge storage tank, in which granular sludge from the anaerobic UASB reactor and/or settling structure is accumulated in advance, while before feeding it into the second equalizer, it is preliminarily dispersed by the cavitation method, diluted with water and the pH is adjusted to a value of 6.5-8.0 units, optimal for activating the enzymatic activity of microorganisms. 4. The method according to paragraph 1, characterized in that wastewater with a calcium concentration of over 100 mg/l is alkalized in an intermediate tank to a pH of 9-10 units with the formation of a sediment, which is removed by flotation treatment, after which an acidic reagent is dosed into the pre-oxidation tank to reduce the pH to 7.5-8.5, which ensures optimal conditions for the subsequent supply of purified water to the anaerobic UASB reactor. 5. The method according to paragraph 1, characterized in that, if it is necessary to reduce the load of organic substances on the UASB reactor, provision is made for feeding a stream into a pre-oxidation tank for mixing with the stream sent to the UASB reactor, which ensures a reduction in energy costs for heating and a reduction in the amount of dosed biogenic nitrogen feed due to the nitrogen-containing organic compounds contained in the stream. 6. The method according to paragraph 1, characterized in that the dewatered sludge is sent to a paddle-type drying apparatus, where it is thermally processed with a reduction in volume and residual moisture, after which the dried sludge is unloaded into a sludge container and transported to a landfill, the resulting vapors are cleaned by a wet method in a scrubber and the resulting contaminated waters are discharged into the first equalizer. 7. The method according to paragraph 1, characterized in that the biogas accumulated in the gas holder is sent to a biogas purification system with subsequent feeding to a gas boiler for generating thermal energy, while the generated heat is used to heat the heating water, which acts as a coolant in the heat exchanger, which ensures a closed energy cycle and compensation of energy costs due to the use of its own energy generating unit.