RU1834859C - Method for purification of sewage water at cattle-breeding farms "ekotechproekt" - Google Patents

Abstract

The invention relates to methods for treating wastewater of livestock complexes and can be used, in particular, for treating wastewater of winery complexes. The method includes the homogenization of wastewater, its separation into liquid and. solid fraction with subsequent stages of sedimentation, biological treatment with aeration and post-treatment with ozonation of the liquid fraction and biothermal composting of the solid fraction together with sediments formed during sedimentation and biological purification, and sedimentation is carried out in a thin-layer sedimentation tank in the presence of coagulant and biological flocculant, purification is carried out with countercurrent flow of activated sludge, and ozonation is carried out in a suspended layer of a heterogeneous catalyst. The method provides a reduction in capital, energy and operating costs while maintaining a high degree of purification. 9 s.p. f-ly, 1 ill.

Description

The invention relates to methods for treating wastewater from a livestock complex and can be used, in particular, for treating wastewater from pig farms.

The aim of the present invention is to reduce the capital, operating and energy costs of its implementation for the treatment of highly concentrated effluents, in particular, effluents of pig-breeding complexes while maintaining a high degree of purification.

The drawing shows a schematic flow diagram of a method.

The circuit includes a homogenizer 1; drum sieve with screw compactor 2; thin-layer. tubular baffles 3, 7, 9; pre-aerator 4; biocoagulant 5; first stage aeration tanks 6; second stage aeration tanks 8; sedimentation tank 10; centrifugal thickeners 11; composting system 12; blower station 13; ozonizer 14; post-treatment column (contact device) 15; dispenser, catalyst 16; system

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catalyst recovery 17; reagent preparation for preparation of coagulant 18,

The following are elements of the invention in the technological order of their use.

At the stage of mechanical treatment of wastewater in order to intensify the process and increase the efficiency of separation of wastewater into liquid and solid fractions, it is proposed to use thin-layer, for example, tubular sumps, which, with equal productivity, can reduce their working volume by two to three times in comparison with those usually used for this goals vertical sedimentation tanks. In addition, the effectiveness of the settling process is enhanced by introducing a centrifugal precipitate from the centrifugal thickeners, which acts as a bioflocculant, into the sump. At the same time, an alkaline reagent is introduced into the sump as a coagulant, the role of which, for example, can be played by ash obtained from burning coal. These factors increase the efficiency of cleaning from suspended particles up to 80-85% (this value according to the known method with vertical sedimentation tanks is about 50%).

One of the main elements of the proposed cleaning method is a counter-active activated sludge system, which is carried out in the following ways: activated sludge from the sludge of the second stage of biological treatment is fed into the aeration tank of the first stage; activated sludge from the sludge of the first bio-treatment stage is fed to a pre-aerator and a bio-coagulator.

The countercurrent movement of activated sludge provides the solution of the following problems: dilution of highly concentrated initial effluents at the first stage of biological treatment due to the supply of less concentrated effluents from the second stage together with activated sludge; reduction of air flow at the first stage of bio-purification due to the influx of additional oxygen in the form of nitrates and nitrites (their content in the active sludge at the end of the second stage is 1.00 - 50 mg / l). This allows to reduce the required power of blowers and the required energy consumption; an increase in the degree of wastewater treatment at the stage of bio-coagulation, since activated sludge supplied to the by-coagulator from the 1st aeration tank acts as a coagulant; the one-oil bioremediation principle provides a high inertia of the entire bio-treatment system, making it insensitive to possible sharp changes in the concentration of pollution.

The air in the aeration tanks in the proposed method is supplied through porous, for example, tubular elements (filters) made of titanium or its alloys and having oxynitride coatings on the external surface in contact with the treated effluents. Titanium,

selected as the material for the manufacture of filters, has a high corrosion resistance in relation to the processed. drains. The oxynitride coating ensures the absence of wettability of the surface of the filter by the liquid fraction of the effluent, and, therefore, a negative capillary effect. The filters are placed uniformly throughout the area of the aeration tanks. They have porosity in

0 range of 30-60% and pore size of 20-150 microns. With such parameters of the porous elements, the wall thickness of the filters is 4-10 mm and the pressure in the air duct is 0.4-0.6 atm, the optimum air flow rate and the size of the air bubbles entering the aerothen are 1-3 mm.

With the described technology provides intensive mixing of the contents of the aeration tanks in the entire volume, large

0 the reaction surface due to the small size of the bubbles, the intensive process due to the maintenance of a high concentration of activated sludge in the aeration tank - at the level of 6-8 mg / l.

5 The post-treatment of the liquid fraction in the proposed method is carried out in a suspended layer of a heterogeneous catalyst and an ozone-air mixture. The catalyst can be substances containing metals

0 variable valency, e.g. iron and dispersed form, which provides a large amount of active surface of the catalyst. Such a catalyst can serve, for example,

5 powdered activated carbon or ash of brown or bituminous coals. Ash is the preferred reagent as cheaper and more affordable. It was found that the optimal concentration range

0 of the catalyst in suspension is 0.5-5.0 g / p.

The design of the column in which the post-treatment takes place involves the supply of the ozone-air mixture in the axial direction5 (through the filter), and the treated effluents and catalyst suspension in the tangential direction. This provides intensive mixing of the components and active oxidation processes.

From the effluents that underwent a post-treatment operation, a catalyst dispersed therein is then isolated. For this operation, for example, a thin layer sump and a centrifugal thickener are used. The catalyst recovered from the effluent is again returned to the post-treatment stage. Such recycling of the catalyst substantially reduces its consumption.

The ozone-air mixture that has not reacted at the post-treatment stage, after leaving the column, is sent to the second post-treatment stage. Moreover, it is fed into the aeration tank through a hydro-acoustic emitter, which, creating a jet-cavitation field with a frequency of oscillations of 3-12 kHz, significantly activates the ozone-air mixture due to its dispersion and additional formation of strong oxidizing agents, such as Oz and Ng02. This operation, in addition to the economic aspect, gives an additional technological effect - increasing the degree of bio-treatment at its second stage,

Thus, the higher efficiency of the technology for post-treatment of wastewater in the proposed method compared to the prototype method is due to the following points:

More active oxidation processes in the suspended catalyst bed, which is ensured by the reagent feed circuit for the post-treatment column; using less scarce and cheaper catalyst (ash instead of activated carbon); the use of residual ozone in the post-treatment process, which on the one hand increases the utilization rate of ozone and, on the other hand, eliminates the need for aggregates for the decomposition of residual ozone.

A new element in the technology of processing the solid fraction in a mixture with dehydrated sludge and excessively activated sludge is the method of composting by vacuum-pressure aeration. The essence of the latter lies in the fact that during composting, aeration (purging of the composted mass with air) and vacuum are cyclically alternated. The duration of the aeration period is T5-30 seconds, and the evacuation period is 1-1.5 hours. Such a sequence of operations ensures the intensive flow of the aerobic process due to the supplied air and regular removal of gaseous reaction products and excess moisture by vacuum, which ultimately creates favorable conditions for the intensive composting process.

In general, the proposed cleaning method, while ensuring the degree of purification equivalent to the prototype, differs from it in the effect obtained: a shorter process chain due to the elimination or acceleration of a number of operations, and, consequently, greater compactness of the treatment facilities and lower capital costs; a smaller number and the required 0 power of energy-consuming equipment (blowers, pumps, centrifugal thickeners), which reduces energy costs.

For example Wastewater from the pig-breeding complex enters the homogenizer (1) in an amount of 1,500 m / day, having the following composition: dry matter content 13,300 mg / l, COD 13,600 mg / l, BP “5,575 mg / l, NH4 + 600 mg / l PaOs 266 mg / L

0 K20 333 mg / l. After separation of the solid phase on the drum sieves (2), the liquid fraction in the amount of 1610 m3 / day (including drainage from sludge and composting sites) enters

5 vertical thin-layer sump (3). The composition of the liquid fraction at this stage is: BB (suspended solids) 1000 mg / l, COD 10200 mg / l, BOD5 4280 mg / l, MH4 + 600 mg / l, P20s 220 mg / l, “20 333 mg / l, B ash tank is also supplied with ash (liquid phase of leaching of ash from brown coal burning) with a pH of 11. A solid fraction of 280 m / day is transferred to composting. From the primary sump

5 wastewater enters the pre-aerator (4) in an amount of 1300 m / day with the following contents: BB 393 mg / L, COD 5630 mg / L, BOD5 4730 mg / L, NH4 520 mg / L, P20s 150 mg / L / KZO 380 mg / l Excess sludge from aerotanks in the amount of 250 m3 / h with a moisture content of 99% is also supplied here. The precipitate formed in the vertical sump is compacted on a centrifugal thickener (11) to a moisture content of 80%. The sediment in the amount of 60 m / day is sent for composting, and the centrate (250 m3 / day) is again sent to the sump. Wastewater from the pre-aerator enters the biocoagulator (5), where further explosives are separated with an efficiency of up to 80% dry

0 substance. A sediment from a bio-coagulator (350 m / d) with a moisture content of 98% is compacted in a centrifugal thickener, and then also sent to compost.

After biocoagulation, the liquid fraction

5 in an amount of 1500 m3 / day with a concentration of explosives of 1000 mg / l, COD 3000-5000 mg / l, BOD5 2500-3000 mg / l, MLC + 450-750 mg / l, P20s 250-400 mg / l, CaO 150 -300 mg / l is sent to the first stage aeration tanks (6) with integrated secondary sedimentation tanks (7)

0

0

5

and further into the aeration tanks of the 11th stage (8), also equipped with secondary sedimentation tanks (9). The composition of the liquid fraction after bio-purification: BB 75-100 mg / L, COD 250-300 mg / L, NJV 10-20 mg / L, P20s 120-200 mg / L, K20 150-250 mg / L.

Claims (10)

The next stage of processing the liquid fraction - post-treatment and disinfection - is carried out in a contact device (15). Here, the waste water is mixed with an ozone-air mixture (OVS) and a suspension of powdered ash from burning brown coal for 10 minutes. The concentration of ozone in the OVS is 15 mg / l, the amount is 100 me / hour, the ash concentration is 2 kg / m3. The spent OVS with an ozone concentration of less than 1 mg / l is supplied to the second stage aeration tanks. The liquid fraction with a suspension of ash is clarified in pressure filters (17), where the explosives are almost completely removed. The concentrated ash suspension (wash water) is again sent to recirculation in an amount of 1 m / h. Purified wash water has the following composition: B less than 1 mg / L, COD 50 mg / L, BODdb mg / L, NH4 + 5-10 mg / L, P20s 150 mg / L, KgO 500 Mg / L, colorless, transparent, odor on the threshold of sensitivity, disinfected and can be reused. SUMMARY OF THE INVENTION 1. A method for treating wastewater of animal husbandry complexes, comprising homogenizing wastewater, separating them into liquid and solid fractions, the liquid fraction being subjected to sedimentation, biological treatment with aeration and subsequent cleaning by ozonation, and the solid fraction along with precipitates formed during sedimentation and biological purification, is subjected to biothermal composting, excluding and with the fact that the sedimentation is carried out in a thin-layer sedimentation tank in the presence of coagulant and bio-flocculant, bio logical cleanup is carried out with countercurrent flow of activated sludge, and ozonation is carried out in a suspended layer of a heterogeneous catalyst. 2. The method according to claim 1, characterized in that the coagulant used ash from burning solid fuels, such as brown or hard coal. 3. The method according to claim 1, characterized in that as a bioflocculate, a centrifuge of nitrified excess activated sludge of a biological treatment system is used. 4. The method by item 1, characterized in that the dose of activated sludge in the biological treatment system is maintained at a level of 6-8 g / l. 5. The method according to claim 1, with the fact that aeration is carried out through porous filter elements made of titanium or its alloys coated with a titanium oxy nitride film. 6. The method according to claims 1 and 4, with the fact that the porous filter elements have a total porosity of 3060% and a pore diameter of 20-150 microns. 7. The method of pop. 1, characterized in that as a heterogeneous catalyst in the process of refining, ash is used from burning solid fuels, for example, brown coal 8. A method according to claims 1 and 6, characterized in that the ozonation is carried out with a catalyst concentration of 0.5-5.0 g / l "h. 9. The method according to claims 1 and 7, with the exception that the unreacted ozone is introduced into the biological treatment stage through a sonar emitter with an oscillation frequency of 3-12 kHz. 10. The method according to claim 1, from l and ch and yuschi and the fact that biothermal composting solid fraction together with a compacted mixture of sediment formed during sedimentation and biological treatment, is carried out with vacuum-pressure aeration.