RU2497762C2 - Method of biological purification of household-fecal sewages with sharply changing in time consumptions and compositions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to methods of biological purification of household-fecal sewages and can be applied in community facilities for purification of municipal and industrial sewages. Method includes collation of water, settling, averaging its expenditure, processing sewages with communities of hydrobionts from bacteria to zooplankton, afterpurification of water and following disinfection of purified sewages. Air is supplied to stages of bioreactor of multi-sludge system of sewage purification by program, preliminarily formed on the basis of specified values of indicators: content of dissolved oxygen, suspensions, pH, Eh, oxidability and content of nitrogen ammonium and nitrate, which are updated daily. Value of Eh medium in wire-brush nozzle by impulse supply of air in bubblers is supported at level +50…+120 mV at the stage of denitrification and introduction of anammox process, and not less than +300 mV at stage of nitrification termination. Recirculation flow of nitrificated discharge return is assigned by ratio (N-NH₄ ⁺)"вх"/10. Discharge pH value at the stage of nitrification termination is supported not less than 7. Carrying out of suspensions from stages of sewage afterpurification is not allowed to be over 3 mg/l, with N-NH₄ ⁺ concentration being not higher than 0.4 mg/l.

EFFECT: invention makes it possible to increase stability of operation of purifying stations and regulate their exploitation.

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Description

The invention relates to methods for treating household and fecal wastewater and can be used in municipal services for the treatment of urban and similar industrial wastewater in composition.

It is known to use traditional technology for wastewater treatment, including mechanical treatment facilities: grates, sand traps, primary sumps; biological treatment facilities: aeration tanks, secondary sedimentation tanks; deep treatment facilities: filters, contact tanks; facilities for the treatment of emitted sewage sludge: sludge collectors, sludge sites or mechanical dewatering apparatus [1]. The traditional technology has been improved by using microorganisms attached to the brush nozzle, which has reduced the specific sizes of treatment plants, energy costs, and improved the ecology of treatment plants [2]. The known method, which improved the traditional technology of wastewater treatment, excluded the use of primary clarifiers at the mechanical cleaning stage, and added the use of a ruff nozzle to retain biocenoses of attached microorganisms at the biological cleaning stage and recommended the use of secondary thin-layer settlers. The practical experience in implementing the three-way biological wastewater treatment method [2] has shown its high efficiency and stability of the quality of treated water for wastewater from cities and towns with a stable number of inhabitants. Meanwhile, there is the practice of shift camps, tourist centers, housing estates for hosting sports competitions with the temporary stay of athletes and fans.

The specifics of household-fecal wastewater of this type of housing consists in a sharp change in time of the costs and composition of wastewater. During the competition, there is a lot of runoff and pollution in them in the same quantities, and in the absence of competition and runoff is small, and pollution in them of a different composition, because general food items, dry closets, etc. do not work With sharply changing costs and compositions of domestic and fecal wastewater in treatment plants that operate even using the three-strand biological wastewater treatment method [2], there is no stability in the quality of treated water.

The objective of the invention is to increase the stability of the treatment plants of deep biological treatment, the regulation of the operation of the treatment plant.

The problem is solved by the fact that after mechanical treatment with averagers of wastewater costs and reagent sedimentation, a multi-force system is used, focused on the use of exclusively biocenoses attached to the brush nozzle from bacteria to zooplankton at all stages of wastewater treatment, and thin-layer settlers are included in the work only at the stage commissioning of sections of the treatment plant, as well as for precipitation during the regeneration of wastewater filters. At the stages of denitrification and nitrification, the aeration intensity controlled by the automation system is made by measuring the concentration of dissolved oxygen and Eh of the medium in the treated wastewater with air supply directly under the brush nozzle, and at the stage of biological treatment, airlift aeration and circulation of the treated sewage water through the stationary brush nozzle with sectional periodic regeneration of the brush nozzle by supplying air under the after-treatment brushes with emptying of the bioreactors of the after-treatment into thin-layer Removal stoyniki washed with ruff sludge particles from the sludge mixtures. The regeneration of the after-treatment compartments in each section is carried out with the section turned off to allow wastewater to pass with a minimum inflow to the treatment plant. For coagulation and flocculation of suspensions in front of thin-layer primary sedimentation tanks and sludge separators, coagulation and flocculation reagents are added to the sludge mixture and initial stock.

Analysis of known technical solutions related to wastewater treatment methods showed that technical solutions containing the same set of essential features as the claimed method were not found. This allows us to conclude that the claimed method meets the criterion of "novelty."

Analysis of the identified significant distinctive features from the prototype showed that such or similar features in known technical solutions with the manifestation of the same properties were not found, which allows us to conclude that the claimed method meets the criterion of "significant differences".

The claimed combination of essential features allows you to get a new, higher result, expressed in providing a deeper and more stable wastewater treatment.

The method is illustrated by the technological scheme of wastewater treatment and thickening of precipitates at the sewage treatment plant of the village shown in the drawing. The positions indicated:

1. The flow of source wastewater

2. Lattices

3. Sand traps

3. Water measuring tray

4. The average cost

four'. Submersible pump

5. Distribution chamber

6. Bioreactor multi-force system of microorganisms

7. Tanks of the denitrification and nitrification compartments

8. Cassette with ruff

9. The introduction of the sludge mixture in the sinuses 15 of a thin-layer sump 10

10. Thin-layer sedimentation tank

11. The air supply to the system of bubblers 17 regeneration of the shelf space 16 of the sump 10

12. Partitions

13. Sealing chamber

14. Drainage tray

15. Sinus of a thin-layer sump 10 for entering the sludge mixture

16. Shelf space of a thin-layer sump

17. Aeration bubblers

18. Nadilovaya water

19. The pipeline drainage compacted sludge for mechanical dewatering

20. Workshop for mechanical dewatering of sewage sludge

21. The filtrate pipeline from the workshop 20 mechanical dewatering of sewage sludge

22. The flow of dehydrated sludge and waste for disposal

23. Ducts

24. Blower

25. Garbage stream from grates 2

26. Sand trap 3

27. Airlift return of activated sludge mixture

28. Sludge return pipe

29. Treated wastewater

30. The building of the Ural wastewater

31. Treated wastewater disinfected in the Ural Federal District

32. Shut-off control valves controlled by automation

33. Automation node

34. Sampling points for chemical analysis

35. Waste water recirculation flow

36. Reagent farm

37. Sediment of primary sedimentation tanks 38

38. Primary sedimentation tanks

Wastewater stream 1 enters the sewage treatment plant (WWTP), is screened in grids 2, settles in sand traps 3, passes through a water metering tray 3 ', flow averager 4 with submersible pumps 4', settles in primary settling tanks 38 with the addition of reagents 36 and enters into the distribution chamber 5, from which the wastewater is distributed to separate independent of the same purpose and content sections 6 of the bioreactors of the multi-force system of microorganisms and hydrobionts.

Each section 6 of bioreactors includes compartments 7 of nitridenitrification tanks, separated by partitions 12 having a communication between adjacent compartments 7 through overflows at the bottom or upper spillways.

All compartments 7 are equipped with cassettes 8 with a brush nozzle and aeration bubblers 17 connected by air ducts 23 to the blower 24. Moreover, the bubblers 17 are evenly distributed under the cassettes 8 with a brush nozzle.

Each section communicates with a separately located thin-layer sump 10, having sinuses 15 for inlet of sludge mixture 9, a shelf space 16 for thin-layer separation of sludge mixtures, airlift 27 for supplying activated sludge to the sludge return pipe 28 into compartments 7 of the nitridenitrification tank, drainage trays 14 for sludge water removal and filtrate from the workshop 20 to the distribution chamber 5, the compacted activated sludge accumulation chamber 13 with the condensed sludge discharge pipe 19 and sediment 37 of the primary settlers in the mechanical dewatering workshop 20 adka wastewater. Sludge and waste 25 from the gratings 2 dehydrated in the workshop, as well as sand pulp 26 from the sand traps 3, are fed by stream 22 to preparation for disposal as building materials and organic fertilizer.

The air supply through the air ducts 23 to the bubblers 17 is controlled by a shut-off and control valve 32, controlled by the automation unit 33. The purified wastewater after the after-treatment stages enters through pipelines 29 to the disinfection building 30 for processing with ultraviolet rays, and then through pipelines 31 it is discharged to a surface water body or sent for use for technical water supply. At points 34 of the distribution chamber 5 and in the Ural Federal District building 30, wastewater samples are taken for chemical analysis, which makes it possible to compile a program for the automation unit 33 for supplying air from the blower 24 by controlling the blowers and shut-off and control valves 32.

The proposed scheme works as follows. Wastewater stream 1 enters the filter 2, where they are freed from large mechanical impurities (larger than 3-5 mm). Next, the effluents are defended in the sand traps 3, where they are separated from the sand, which is discharged by stream 26 together with stream 25 of waste from filtering units 2 for processing and preparation for disposal. From the sand traps 3, the wastewater enters the water metering tray 3 'and then to the averagers 4 with a submersible pump 4' and primary sumps 38 with the addition of reagents 36, and then to the distribution chamber 5. From the distribution chamber 5, the effluents are diverted into separate sections 6 of the bioreactors. The source wastewater in each section is diluted with a circulating 35 stream of wastewater from the last compartments of the nitrification bioreactors 7. In each section of the 6 bioreactors, the volumes of the sections are divided by partitions 12 into compartments 7 at the beginning of denitrification and then nitrification. Inside the compartments 7 there are cassettes 8 with a brush nozzle. On the bottoms of compartments 7, bubblers 17 are laid, connected to the blower 24 through air ducts 23, equipped with shut-off and control valves 32 controlled by the automation unit 33. The signal to close or open the air supply to each compartment of 7 sections 6 of bioreactors is carried out by node 33 on the basis of a program based on information obtained from chemical analysis of wastewater samples taken at points 34 of the technological scheme of the treatment plant. At the same time, in the samples of wastewater, the pH and Eh values of water, oxidation, dissolved oxygen, nitrogen content of ammonium and nitrate, suspended substances are measured.

During the commissioning work on putting the sewage treatment plant into operation in each section, either the biocenosis of microorganisms is grown on real wastewater, using a separately located thin-layer sedimentation tank 10.

At the same time, the seed of activated sludge taken from a sewage treatment plant of another sewage facility is adapted to the wastewater of the constructed treatment plant and increased by recycling activated sludge settled in a thin-layer settling tank 10 by means of airlift 27 and pipe 28 from under the shelf space 16 to the entrance to the launched section 6 bioreactor. The supply of sludge mixture through pipelines 9 in the sinuses 15 of a thin-layer sump 10 is carried out from the last nitrification compartment 7, located in the start-up section 6 in front of the aftertreatment compartment. After fouling of the brush nozzle in the cassettes 8 of the starting section 6, the thin-layer settler 10 begins to be used to sludge suspensions of the launched section from the regeneration of the brush nozzle of the wastewater treatment compartment. The regeneration of the ruffs of the wastewater treatment compartments is carried out during the period when the minimum flow of wastewater arrives at the treatment plant, when the regenerated sections can be turned off from the wastewater treatment and purification process. Other sections 6 are started by moving part of the cassettes 8 with the nozzle overgrown with hydrobionts from the already commissioned section to the neighboring one, and a thin-layer sump 10 is used only to remove suspensions from the regeneration sludge mixture of the wastewater treatment compartments. From the wastewater treatment compartments, the purified water is discharged through pipelines 29 to the building 30 of the Ural Federal District, and disinfected water is discharged through a pipe 31 to a surface water body. The sludge separated in the thin-layer sump 10 is collected by the pipe 19 into the chamber 13, and from it, together with the sludge 37, the primary sumps 38 are supplied to the workshop 20 for mechanical dewatering of sewage sludge. Nadil water from a thin-layer sump 10, collected by the tray 14 through the nadil water pipeline 18 together with the filtrate from the workshop 20, enters the distribution chamber 5 through the pipeline 21, and the dehydrated sludge stream 22 is removed to prepare for disposal as organomineral fertilizer or soil for the restoration of disturbed territories. Regeneration of the shelf space 16 in the thin-layer sump 10 is carried out by supplying air through a pipe 11 to the bubblers 17 located under the shelf space 16.

To explain the parameters of the wastewater treatment process and evidence of solving the tasks, we give an example of the implementation of the claimed method at treatment plants in the region of Sochi.

Example. On the highway of the railway under construction from the village. Adler, Sochi in the village Krasnaya Polyana shift camps were built for the construction of the railway. In shift camps there are 2000 ... 2500 people per day. Permanently located in shift camps, no more than 100 people. From 150 to 250 m ³ / day of wastewater, sewage treatment plants (WWTP) of shift camps receive water, but with a large irregularity in the hourly flow and flow rate. To partially equalize the costs and composition of wastewater at WWTP, flow averagers and sedimentation tanks with preliminary introduction of reagents (coagulant and flocculant) to remove suspended solids and organic impurities dissolved in water are provided after mechanical treatment. After mechanical wastewater treatment, ammonia nitrogen, a small amount of suspended matter and dissolved organic substances remain in them. An anaerobic-aerobic biotechnology for the deep treatment of wastewater from nitrogen compounds and residues of suspended solids and organic impurities in six-stage two-section bioreactors with recirculation of the treated wastewater from the bioreactor exit, filled in all stages with cassettes with a ruffled nozzle and with a controlled supply to air levels to maintain certain pH, Eh, oxidizability, suspended solids, ammonium nitrogen and nitrite nitrogen and nitrate values in the wastewater treatment stages Comrade. Observations of scientists of the Institute. Vinogradsky in biocenoses held by a ruff nozzle, anammox bacteria were recorded. The recirculation flow of effluents from the fifth stage to the first was established by the ratio (N-NH ₄ ⁺ ) in / 10, because there is a restriction on the content of nitrates in purified water not more than (N-NO ₃ ^- ) ≤9.1 gN / m ³ . For example, (N-NH ₄ ⁺ ) x = 26 g N / m ³ , then Krets = 2.6. The total flow of effluents will be: Qpacc + 2.6Qpacch and the concentration of N-NH ₄ ⁺ in it will be: (Qpac · 26 + 2.6Qpacch · 0.4) / 3.6Qpacch = 7.5, which is less than 9.1. The higher the initial concentration of N-NH ₄ ⁺ , the greater the Kretz is obtained and closer to 9.1 the concentration of N-NH ₄ ⁺ in the mixture. To maintain the pH in the nitrification zone at a level above 7, an addition of lime or soda (a source of alkali) is needed, since nitrification is accompanied by acidification of water. Alkalization is not a problem if the total alkalinity of the source water exceeds 5.0 mEq / L. Since the content of ammonia nitrogen in the initial household and fecal water usually does not exceed 70 g / m ³ , taking into account the alkalization of the obtained nitrites and alkalinity nitrates at 5 mEq / l during denitrification, it is enough that the pH of the effluent does not drop below 7.

Management of the Eh value of the effluent is necessary so that anammox bacteria can develop. The Eh value of the mixture of the initial effluent having Eh below zero with a recirculated wastewater stream having Eh above +300 mV is obtained at a level of not less than +200 mV, therefore, aeration of the mixture necessary to create mass transfer between the bioreactor microorganisms attached by the biocenosis and waste water, should not introduce much dissolved oxygen, which increases the water Eh, but should provide mass transfer between the hydrobionts attached to the brush nozzle and the treated water, therefore, aeration should be periodic, pulses. This provides an automation unit with controlled shut-off and control valves. The transition to the regeneration of the brush nozzle in the post-treatment stage is controlled by the concentration of suspended solids in the treated water, it should not exceed 3 mg / l. The content of oxygen dissolved in water is not regulated, but Eh at the level of +300 mV is achieved when the concentration of oxygen dissolved in water is more than 4 mgO ₂ / L.

The ammonia nitrogen content in the treated water should be no more than 0.4 mgN / L, therefore, fixing this value is necessary to control the wastewater treatment process. Initially, when designing bioreactors for wastewater treatment, knowledge of the BOD value of wastewater after primary sedimentation tanks with reagent treatment is necessary. From operating experience it was found that the load on the biomass of hydrobionts in bioreactors should not exceed 50 kg of BOD / ton of biomass per day. The biomass of hydrobionts can be taken equal to the mass of the brush nozzle in all stages of the bioreactors. The volume of bioreactors can be assigned based on the possibility of retaining in 1 m ^{3 the} volume of not more than 3 kg of a brush nozzle and, therefore, the biomass of hydrobionts.

Information sources

1. Voronov Yu.V. et al. Water disposal: Textbook. - M.: INFRA-M, 2007 - 415 p.

2. A three-way biological wastewater treatment method. Patent No. 2264353 C2 C02F 3/03. Publ. 11/20/2005, Bull. Number 32. Patent holder: Kulikov N.I.

Claims (1)

The method of biological treatment of domestic and fecal wastewater with drastically varying costs and composition, including filtering water to isolate large mechanical impurities, settling to remove sand and other impurities from wastewater, averaging wastewater flow rate, treating wastewater with hydrobiont communities from bacteria to zooplankton for water purification from dissolved organic substances and nutrients and the subsequent disinfection of treated effluents for the destruction of pathogenic microorganisms, from characterized in that in the multi-strand biological wastewater treatment system, all sludge systems mainly use biocenoses of microorganisms attached to the brush nozzle, thin-layer settlers are used only to thicken the sludge from the regeneration of the brush brush of the wastewater aftertreatment stages and during commissioning, the circulation flow of purified water return - the source of nitrites and nitrates is organized from the stages of completion of the process of nitrification of ammonia nitrogen of wastewater to the input of effluents into bio reactor; at all stages of biological wastewater treatment with nitri-denitrification processes, air is used as an oxygen source and a means of mass transfer between microorganisms attached to the brush nozzle and the treated wastewater with its supply to the brush nozzle, and air is supplied through airlift niches at the wastewater treatment stage in the process of wastewater treatment and under the brush nozzle at the stage of regeneration of the ruff after-treatment of accumulated suspensions; sections in which the stages of wastewater treatment are subjected to regeneration of the brush head are removed from the wastewater treatment scheme, and during the period of stable operation of the treatment plant, they are involved in the technology of preparing wastewater for disinfection; the regeneration of ruffs in the after-treatment steps is carried out with a minimum influx of wastewater to the treatment plant; the air supply to the stages of the bioreactor of the multi-force biological wastewater treatment system is controlled by shut-off and control valves on the air ducts according to a program preliminarily compiled on the basis of these indicator values: dissolved oxygen, suspended matter, pH, Eh, oxidizability and nitrogen content of ammonium and nitrate and updated daily, the value of Eh of the medium in the brush nozzle by pulsed air supply to the bubblers is maintained at the stage of denitrification and the anammox process at + 50 ÷ + 120 mV, and at the stage nitrification completion of not lower than 300 mV; the recirculation flow of the return of nitrified runoff is assigned by the ratio (N-NH ₄ ⁺ ) in / 10, the runoff pH at the stage of completion of nitrification is maintained not lower than 7, the removal of suspensions from the wastewater post-treatment stage is not allowed above 3 mg / l, and the concentration N- NH ₄ ⁺ not higher than 0.4 mg / L.

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