RU2351549C2 - Denitrification flotating plant - Google Patents

Abstract

FIELD: sewage treatment facilities.

SUBSTANCE: invention is related to devices for purification of household and industrial sewage waters. Denitrification flotating plant includes flotating settling tank equipped with hydrophobic nozzle in the form of capronic or lavsan fiber bristle brushes fixed in cassettes in the whole area of cross section of flotating settling tank vertically with pitch equal to diameter of bristle brushes, with height of cassettes of at least 1 m. Inlet of initial sewage water and utilities for inlet of recirculating sewage water are located above cassettes with bristle nozzle. Plant is equipped with detector of nitrates content in water installed in inlet pipeline of purified sewage water recirculation. Plant is equipped by solution tank of concentrated solution of nitrates and batcher of this solution that communicates to pipeline of purified sewage water recirculating flow inlet; under cassettes with bristle nozzle regeneration bubblers are installed, which communicated to system of air supply through magnet valve controlled by controller. Inside flotating settling tank there are nozzles for inlet of initial sewage water and recirculating flow of purified sewage water that are located tangentially to shell of flotating settling plant body.

EFFECT: reduction of power intensity, simplified operation, exclusion of foam product contamination by reagents.

2 cl, 1 dwg

Description

The invention relates to devices for flotation treatment of domestic and industrial wastewater and can be used in the treatment technology of the named wastewater.

Known flotation system, including flotation tank, saturator with pressure reducing valve that keeps the pressure of the air-water mixture "to yourself", a circulation pump and compressor to create pressure in the pressure tank and dissolve the air in water. When depressurizing a wastewater in a flotation tank, air dissolved in it in the form of bubbles is released. At the same time, finely dispersed hydrophobic or hydrophobized hydrophilic particles adhere to the bubbles and, in the form of particle-bubble complexes, float to form a foam layer. The foam layer is removed with a special device from the surface of the water mirror of the flotation tank, and the purified liquid is discharged from the zone below the formation of particle-bubble flotation complexes [1].

Using the known flotation system does not allow to achieve the efficiency of wastewater treatment from hydrophobic impurities above 70 ... 80%. A part of the air bubbles follows the flow of the wastewater being cleaned and, together with a particle of adherence adhering to it, is removed from the flotation tank.

The closest technological solution that improves the efficiency of wastewater treatment is a biological wastewater treatment plant that implements deitrification of wastewater and activated sludge flotation, disclosed in utility model RU 9456 U1. 03/16/1999 (D1) [2].

In the well-known structure, which includes an aeration tank — a displacer with a flotator in the last aeration tank corridor for separating activated sludge and returning it to the aeration tank head with an inert nozzle to hold attached denitrifying microorganisms after the flotator, flotation is carried out exclusively by introducing a water-air mixture from a special device into the treated wastewater and nitrides are subjected to denitrification, obtained directly in the aeration tank - a displacer from the pollution of the initial runoff.

The disadvantages of this structure are: high energy consumption of the device for introducing a water-air mixture into the flotator and denitrification of oxidized forms of nitrogen is difficult due to the low content of organic substances in wastewater in aeration tanks after floaters.

The objective of the invention is to reduce the energy intensity of the flotation system, simplify its operation, increase the efficiency of denitrification.

The tasks are solved in that the denitrification flotation plant, including a flotation tank and flotopen storage, is equipped with a hydrophobic nozzle in the form of nylon or lavsan fiber ruffs, mounted in cassettes over the entire cross-sectional area of the flotation tank, vertically, with a step equal to the diameter of the ruffs, with a height not less than 1 m, the inlet of the source wastewater and communications for introducing recirculated purified water is placed above the cassettes with a ruff nozzle, the ruff nozzle is populated with microorganisms - denitr if there are no recirculated purified water in the flow or if there is a nitrate content in it, installed in the purified water recirculation inlet pipe, it is less critical, providing a stable flotation effect due to microbubbles of nitrogen gas released during biological denitrification, denitrification plant provide a solution tank of a concentrated nitrate solution and a dispenser of this solution, in communication with the recirculation flow inlet pipe ka purified water; under the cassettes with a ruffled nozzle, regeneration bubblers are installed, connected to the air supply system through a magnetic valve controlled by the controller. Inside the flotation tank, the inlet nozzles from the input of the wastewater and the recirculated stream of purified wastewater are located tangentially to the shell of the flotation tank to create a rotational movement of the entire volume of fluid inside the flotation tank and to ensure the separation of microbubbles of nitrogen gas from denitrification cells and mass transfer between microorganisms and the treated wastewater.

Patent studies have shown that neither in the patent nor in the scientific and technical literature there is information about flotation plants for the treatment of domestic and industrial wastewater of the design proposed in the claims, which suggests that the proposed flotation device meets the patentability criterion of "novelty" .

A comparative analysis of devices that are used in well-known technical solutions, including in practice, showed significant features that distinguish the proposed solution.

The advantages indicate that the tasks that are solved are performed at the inventive step, since they do not follow obviously from solutions known in the art and therefore meet the patentability criterion of "inventive step".

The proposed denitrification flotation plant for the treatment of domestic and industrial wastewater is shown in the drawing in the form of a technological scheme.

Denitrification installation includes:

1. Flotation tank.

2. The shell of the cylindrical housing of the sump 1.

3. Flotopen storage.

4. Cassette for attaching nozzles from ruffs.

5. Kapron or lavsan fibrous ruffes.

6. Pipeline for the supply of source waste water to the flotation tank 1.

7. Inlet nozzle of the initial waste water into the flotation tank 1.

8. Pipeline for recirculated wastewater.

9. The nozzle of the inlet of the recirculation stream of purified wastewater into the flotation tank 1.

10. Bubblers of regeneration of the brush nozzle.

11. The piping of the air supply system of the treatment plant.

12. The magnetic valve.

13. The controller.

14. The sensor of the content of nitrates in the recycle stream of treated wastewater.

15. Mortar tank of concentrated nitrate salt solution.

16. Dispenser of a concentrated solution of nitrate salt.

17. A pump with communications for supplying a recirculated stream of treated wastewater.

18. The receiving chamber of the source wastewater.

19. The pipeline drainage of treated wastewater from the sump 1.

20. Foam pipe from flotation tank 1 in the drive 3 flotopen.

The denitrification flotation plant works as follows.

The source wastewater from the receiving chamber 18 through the pipe 6 through the nozzle 7 is let into the flotation tank 1 by gravity, but with an inlet speed that ensures self-cleaning of the inlet pipe 6, since it cannot be blocked by impurities of wastewater. This speed corresponds to approximately 1 m / s. The kinetic energy of the incoming sewage stream 1 entering the sump 1 contributes to the rotation of the liquid inside the sump and erosion of the incoming sewage stream over the entire cross section of the sump 1.

Through a pipe 8 through a nozzle 9, a flow of recirculated wastewater is also fed into the flotation tank 1 through a pump 17 with communications. This flow is also introduced tangentially to the shell 2 of the cylindrical body of the flotation tank 1, closely and in the same direction with the pipe 6 and the nozzle 7 of the inlet of the original waste water. Therefore, these two flows of wastewater guarantee a steady rotation of the entire mass of water inside the flotation tank 1 over its entire height, including the volume occupied by cartridges 4 with nylon or lavsan fiber ruffs 5. Since the mixed stream of the source and recirculated wastewater contains nitrates, organic substances and biogenic elements, then when the flow moves in a spiral through the brush nozzle 5 in the cartridges 4 to the pipeline 19 for the removal of purified waste water from the flotation tank 1, it comes into contact with denitrifying microorgan zmami, retained Ershovoy nozzle 5 within the cassette 4. Microorganisms-denitrifiers, being heterotrophic bacteria use nitrate as the source of oxygen for the oxidation of organic matter of sewage and their growth, cells from releasing microbubbles of nitrogen gas.

Since the surface of the kapron or lavsan fibers of ruff 5 is hydrophobic, it coalesces micro bubbles, but the turbulence of the rotating flow of wastewater in the brush nozzle prevents micro bubbles from coarsening to large gas bubbles. Gas bubbles rise upwards under the action of gravitational forces, picking up hydrophilic particles and substances hydrophobic or hydrophobized through synthetic surfactants on their way. Physicochemical forces work in the flotation zone, leading to wastewater treatment, removal of up to 70-80% of wastewater impurities, mainly poorly soluble in water, in the foam layer of flotopen.

And inside the space occupied in flotation tank 1 by cartridges 4 with a brush nozzle 5, biological processes predominate, leading to a decrease in the amount of organic substances and nutrients dissolved in water. If there are protein substances in the wastewater (this is characteristic of tanneries effluents), it is advisable to use nitric acid as nitrates, since it reduces the pH of the effluent and brings it closer to the isoelectric point pH 4.5, at which the proteins have a minimal charge and therefore amenable to flotation removal into the foam layer with a greater effect. During denitrification, alkali is released inside the brush nozzle and the pH of the effluent rises to the initial value.

If the quantity of nitrates in the treated wastewater of the circulating stream is small, then the sensor 14 of their content will detect this and turn on the dispenser 16 for supplying a concentrated nitrate solution from the solution tank 15.

Once a day, with a minimum influx of effluents from the receiving chamber 18, the controller 13 disables the purified waste water recirculation pump 17, opens the solenoid valve 12 and supplies air from the sewage treatment plant’s air supply system to the bubblers 10 for regenerating the brush nozzle. Excessive biomass is removed with bubble bathing. Since before the bubbling and regeneration of the ruff from the flotation tank 1 is started, the foam layer is removed through the foam pipe 20 to the flotation foam tank 3, when bubbling wastewater under the ruffs, all water is mixed in the flotation tank. After the regeneration of the ruffs, the wastewater is turned on from the recirculation pump 17, the introduction of nitrates and gas bubbles are pumped into the foam layer to the foam pipe 20 and the excess biomass of denitrification microorganisms removed from the ruff, and the contaminants of the initial wastewater entering the flotation tank 1 with new portions of wastewater .

The height of the ruffle nozzle layer was determined based on the intensity of the nitrate denitrification process by autotrophic denitrifying bacteria and their amount held by ruffs, and the estimated residence time of the mixture of the initial wastewater and the flow of recirculated purified water in the denitrification flotation plant.

на уровне 1 г/м³ на выходе стоков из флотоустановки удельная скорость денитрификакции составляет 5…6 г

/кг·час. При имеющейся концентрации биомассы прикрепленных на ершах микроорганизмов не менее 5…6 кг/м³ объема кассет для получения экспериментально выявленных необходимых 10 л/м³ газовых пузырьков нужно денитрифицировать 10 г

/м³ смеси стоков, что потребует около 0,33 часа пребывания смеси стоков в зоне размещения ершовой насадки или около одного часа нахождения смеси стоков во флотоустановке и наличия в 1 м³ смеси стоков концентрации нитратов не менее 10 г

/м³ или в потоке рециркуляционной очищенной сточной воды около 20 г

/м³. Поскольку такая концентрация нитратов в очищенной сточной воде недопустима для выпуска в поверхностный водоем, то дозирование дополнительного количества нитратов в большинстве случаев необходимо.Our studies have previously found that for concentration

at the level of 1 g / m ³ at the outlet of effluents from the flotation unit, the specific denitrification rate is 5 ... 6 g

/ kg · hour. If the available biomass concentration of microorganisms attached to ruffs is not less than 5 ... 6 kg / m ³ of cartridge volume, 10 g must be denitrified to obtain experimentally detected necessary 10 l / m ³ gas bubbles

/ m ^{3 of the} mixture of effluents, which will require about 0.33 hours of the mixture of effluents in the area of placement of the brush nozzle or about one hour of the mixture of effluents in the flotation system and the presence of 1 m ^{3 of the} mixture of effluents with a concentration of nitrates of at least 10 g

/ m ³ or in a stream of recirculated wastewater about 20 g

/ m ³ . Since such a concentration of nitrates in treated wastewater is unacceptable for discharge into a surface water body, dosing of an additional amount of nitrates is in most cases necessary.

The implementation of the tasks of the invention provide:

- a significant simplification of the maintenance of the denitrification flotation system is achieved by eliminating the compressor, the pressure tank of the saturator, and the pressure reducing valve;

- reduction of energy consumption is achieved by eliminating the process of introducing air into wastewater, because gas bubbles are formed as a product of the vital activity of denitrifying microorganisms and even during the neutralization of nitrates, the discharge of which with limited wastewater is limited;

- analyzing a set of component equipment, materials and reagents in the prototype and the present invention, the advantage of denitrification flotation plant is obvious both in construction cost and operational costs, along with technological efficiency in wastewater treatment.

Information sources

1. Gvozdev V.D., Ksenofontov B.S. Industrial wastewater treatment and sludge recovery. - M .: Chemistry, 1988, p. 60-76.

2. Construction for biological wastewater treatment. Patent RU 9456 U1, published March 16, 1999 at http // www.fips-ru / cdfi / fips.dll. Authors: Melnikov B.C., Kalyuzhnov V.G.

Claims (2)

1. Denitrification flotation plant for treating domestic and industrial wastewater, including a flotation tank and a flotopen storage device, characterized in that the flotation tank is equipped with a nozzle with a hydrophobic surface made in the form of nylon or lavsan fiber ruffs inhabited by denitrifying microorganisms located along the entire cross-sectional area cassettes with a height of at least 1 m, with a step of vertically fixed ruffs in the cassettes equal to the diameter of the ruff, above the cassettes with a ruff Inlet nozzles for supplying initial wastewater and a recirculated stream of purified water are located, located tangentially to the shell of the flotation tank housing, under the cassettes with a ruff nozzle there are bubblers for the regeneration of the ruff nozzle communicating with the air supply system through a magnetic valve controlled by the controller, and on the recirculated water inlet pipe flotation tank installed sensor for automatic determination of nitrate content in recirculated purified water. 2. Denitrification flotation plant according to claim 1, characterized in that the flotation plant is additionally equipped with a solution tank of a concentrated nitrate solution and a dispenser in communication with the inlet pipe of recirculated purified water into the flotation tank.