KR20030065092A - The procces and apparatus of Livestock wastewater treatment. - Google Patents

Abstract

PURPOSE: Provided are a method and an apparatus for treating livestock wastewater with high efficiency at low cost, the method using organic acid generated by fermentation of pre-treatment sludge as organic carbon source for denitrification to treat wastewater with low C/N ratio, thereby increasing denitrification efficiency and water treatment efficiency, and using heat generated from a bioreactor to heat a fermentation tank to reduce energy consumption. CONSTITUTION: The apparatus comprises a livestock wastewater adjusting tank(3) for storing and equalizing particle-removed wastewater for a predetermined time while aerating for 7 days or more, a centrifugal machine for separating the livestock wastewater into wastewater and sludge, a sludge storage tank, an organic acid fermentation unit including a sludge dissolving tank(6), an organic acid fermentation tank(7) operating under anaerobic condition, a liquid-solid separation unit for separating the fermented liquid into organic acid and solid, and a heat exchanger for heating the organic acid fermentation tank(7), a C/N ratio adjusting unit(11) for adjusting C/N ratio of wastewater by mixing the wastewater separated by the centrifugal machine and the organic acid, a bio-reactor(12) for eliminating organic material and nutritive salts by aerobic or anaerobic reactions, a solid-liquid separation unit(15) for separating the outflow of the bioreactor(12) by coagulation into decant water and sludge and for dehydrating the sludge, and a sterilizing unit for sterilizing the decant water using ozone and infrared lay.

Description

Livestock wastewater treatment process and apparatus {The procces and apparatus of Livestock wastewater treatment.}

The present invention relates to a wastewater treatment using microorganisms in a livestock wastewater treatment plant, which is separated during pretreatment of a livestock wastewater treatment process, and is converted into organic acid by fermenting sludge in a mesophilic anaerobic fermenter to convert nitrogen in the livestock wastewater using the organic acid. It is to effectively remove contaminants such as BOD at the same time.

In the conventional livestock wastewater treatment process, a high concentration of livestock wastewater was centrifuged to lower the concentration, and then treated in a microbial reactor. The livestock wastewater subjected to centrifugation had a very low C / N ratio and thus had low denitrification effect by biological denitrification.

This is because the C / N ratio suitable for biological denitrification should be at least 3-4.

Therefore, in order to remove nitrogen from the wastewater having low C / N ratio through centrifugation, organic carbon such as methanol or acetic acid was supplied from the outside, resulting in a high treatment cost.

Instead of methanol or acetic acid, organic acids produced when fermenting sludge can be used.In the case of fermenting high concentration sludge, etc. with organic acid, in order to ferment in a moderate anaerobic state, the anaerobic organic acid fermenter can be used as an external fuel to maintain an appropriate temperature. Fuel costs were a problem because they had to be heated.

The present invention is a phenomenon in which the temperature of the aerobic microbial reaction tank, anaerobic or aerobic repetition type microbial reactor in the livestock wastewater treatment plant releases about 8,000 to 12,000 kcal of heat per 1 kg of COD when decomposing organic matter by the action of microorganisms. The temperature of the anaerobic organic acid fermentation tank is heated using the heat generated from this microbial reactor to maintain the temperature of 30-38 ℃ throughout the year, and the organic matter is converted into organic acid within a short period of 2 to 3 days under the medium temperature anaerobic fermentation conditions of 15-35 ℃. By using the decomposition, the organic acid generated here is supplied to the organic carbon source during the denitrification of the C / N ratio adjusting tank or the microbial reactor, so that the livestock wastewater having a low C / N ratio without supplying fuel for heating or methanol for denitrification from the outside It is to increase the denitrification efficiency and treatment efficiency and to operate economically.

The technical problem to be achieved by the present invention is the organic acid generated by fermentation in a middle temperature anaerobic condition by using a part of sludge separated in the pretreatment process of livestock wastewater to livestock wastewater with a low C / N ratio in the process of treating livestock wastewater using microorganisms It is to provide livestock wastewater treatment process and apparatus that can be economically operated by supplying to the organic carbon source necessary for denitrification to increase the denitrification efficiency and water treatment efficiency, and heat the mesophilic anaerobic organic acid fermentation tank using the heat generated from the microbial reactor. .

1 is a process chart showing the configuration of the present invention

Explanation of symbols for important parts of the drawings

1.Inlet

2. Dust removal device

3. Livestock wastewater adjustment tank

4. Centrifuge

5. Separation Sludge

6. Sludge Dissolution Tank

7. Organic Acid Fermenter 7-1 Circulating Pump 7-2. heat transmitter

8. Organic Acid Separator

9. Transfer pump 1 10. Transfer pump 2

11. C / N ratio adjustment tank 11-1. Transfer Pump 3

12. Microbial Reactor

13. Treatment water transfer pump

14. Coagulation Reactor 14-1. Flocculant injector

15. Solid-liquid Separator

16. Dewatering device

17. Second C / N Ratio Adjustment Tank

18. Transfer pump 4

19. Interlocking Treatment Facilities

20. Anaerobic Biofilter

21. Aerobic Biofilter

22. Circulation pump

23. Ozone Ultraviolet Disinfection Equipment

The present invention to achieve the above technical problem,

A livestock wastewater adjusting tank for storing the livestock wastewater removed for a certain period of time with a debris removal device for removing contaminants of livestock wastewater;

Abandoning the livestock wastewater adjusting tank with air for at least 7 days to alleviate the toxicity of disinfectants such as livestock wastewater and equalize the quality;

A centrifugal separator for separating the wastewater and sludge from the wastewater of the livestock wastewater adjusting tank and a device for storing the removed sludge;

A portion of the stored sludge is mixed with a high temperature microbial treated wastewater in a secondary C / N ratio adjustment tank and some fresh water for temperature control to dissolve and homogenize a solution of sludge dissolution tank and sludge dissolution tank at anaerobic temperature. A solid-liquid separator that separates organic acids and solids from the fermentation liquid of the organic acid fermentation tank and the organic acid fermentation tank, and a heat exchanger that heats and circulates the treated wastewater of the secondary C / N ratio adjustment tank at the rear end of the microbial reactor to heat the organic acid fermentation tank. Organic acid fermentation process and apparatus configured;

A process and apparatus for appropriately adjusting the C / N ratio in a C / N ratio adjustment tank by mixing the livestock wastewater branched from the centrifuge with the organic acid produced in the organic acid fermentation tank at a predetermined ratio;

A microbial reaction process and apparatus for cross-repeating anaerobic and aerobic treatment of wastewater transferred from the C / N ratio adjusting tank using microorganisms in a microbial reaction tank or purifying organic matter and nutrients using separate treatment tanks;

A solid-liquid separation process and apparatus for solid-liquid separation and sludge dewatering of the treated water transferred from the microbial reaction tank through an agglomeration reaction in an agglomeration reactor;

A C / N ratio adjustment process and apparatus for mixing the organic water produced in the organic acid fermentation tank at a predetermined ratio in the second C / N ratio adjustment tank to the treated water that has undergone the flocculation reaction;

A process and an apparatus for removing organic matter and nutrients from a two-step microbial reactor comprising the anaerobic biofiltration unit and the aerobic biofiltration unit of the wastewater that has undergone the C / N ratio adjustment process; And

It provides a livestock wastewater treatment apparatus and process comprising the step of removing the bacteria and residual organic matter in the wastewater by using ozone and ultraviolet light while passing through the waste water treated in the process.

Hereinafter, the present invention will be described in more detail.

1 is a schematic diagram of a livestock wastewater treatment apparatus according to the present invention, but the following embodiments are described in detail, but the following embodiments are not limited thereto.

The livestock wastewater collected by the livestock wastewater collection vehicle or introduced into the treatment plant through the livestock wastewater conveying pipe is pumped through the inlet 1 by a pump attached to the vehicle or a pump (not shown) installed at the end of the pipe. The livestock wastewater passed through the debris removal device (2) was stored in the livestock wastewater control tank (3) for a certain period of time, and the wastewater was separated from the solids in the centrifugal separator (4). It was made to transfer to the / N ratio adjustment tank 11.

The separated sludge (5) was to be taken out after temporary storage.

A portion of the separation sludge (5) is mixed with a relatively clean and hot wastewater (nearly the same as the temperature of the microbial reactor) from the sludge dissolution tank (6) and a little fresh water. The mixture was adjusted to temperature, mixed together, and dissolved homogeneously by an agitator (not shown). The sludge solution was transferred to an organic acid fermentation tank (7), and the organic acid fermentation tank (7) was a tubular heat exchanger (7-2). The heat exchanger (7-2) was able to circulate the wastewater in the secondary C / N ratio adjustment tank 17 by the circulating pump (7-1).

The sludge dissolved liquid fermented while staying in the organic acid fermentation tank (7) for 2 to 3 days is separated into organic acid and sludge in organic acid separator (8), and the solids are returned to the livestock wastewater adjusting tank (3) for further treatment. The feed pump 1 (9) was fed to the / N ratio adjustment tank (11).

The livestock wastewater mixed with the organic acid in the C / N ratio adjustment tank 11 is transferred to the microbial reactor 12 to purify biologically contaminants and nutrients such as nitrogen, and the treated livestock wastewater is treated with a treatment water transfer pump. (13) is transferred to the coagulation reaction device (14), and temporarily stored, and then injected with the coagulant supplied from the coagulant injection device (14-1) to undergo the coagulation reaction, and then separated into sludge and supernatant in the solid-liquid separation device (15). And the sludge is dewatered and disposed of in the dehydrator 16, and the supernatant is transferred to the secondary C / N ratio adjustment tank 17 for temporary storage, and the organic acid transferred by the transfer pump 2 (10) from the organic acid separation device (8). It was allowed to mix.

The temperature in the microbial reactor 12 is increased by the amount of heat generated when organic matter is decomposed by microorganisms, and in most treatment plants, the temperature of the microbial reactor is maintained at 30 to 38 ° C. and about 30 ° C. even in winter. Since the flocculation reaction and the solid-liquid separation step are performed in a very short time, there is almost no drop in the water temperature, which is almost equal to the water temperature of the water temperature microbial reactor 12 of the secondary C / N ratio adjusting tank 17.

In addition, the wastewater of the microbial reactor 12 has a very high SS concentration of 5,000 mg / l or more, so when it is used in a heat exchanger, it becomes impossible to operate due to blockage of pipes and generation of scale. The wastewater in the solid-liquid separation state of the previous stage was divided into two chambers, and the wastewater was supplied to the heat exchanger (7-2) because the SS concentration was relatively clean and the temperature was high.

The treated water mixed with the organic acid was able to be treated in two paths, one of which was pumped to the associated treatment facility 19 such as a sewage treatment plant connected to the rear end using a transfer pump 4 (18) to provide the associated treatment facility. Treatment.

Another route was to transfer the treated water mixed with the organic acid to the anaerobic biofiltration apparatus 20 using a transfer pump 4 (18) to denitrify and purify the organic matter in the next aerobic biofiltration apparatus 21. .

The treated water purified by the aerobic biological filtration device 21 was transferred to the ozone ultraviolet disinfection device 23, which is the next process, to be purified and sterilized and then discharged.

A portion of the treated water purified by the aerobic biofiltration apparatus 21 was returned to the secondary C / N ratio adjustment tank 17 by the return pump 22 to be reprocessed by the anaerobic biofiltration apparatus 20.

The action of the livestock wastewater treatment process and apparatus of the present invention configured as described above is as follows. Since livestock wastewater is generally high in contaminant concentrations, it is difficult to treat it to the original livestock wastewater in the microbial purification process. Therefore, a large number of contaminants are removed in a centrifuge and then purified in a microbial reactor. .

However, the livestock wastewater after centrifugation has a high C / N ratio compared to the original livestock wastewater, and it is very low C / N ratio, so biological denitrification is often impossible, so it is necessary to adjust it to an appropriate C / N ratio. For the purpose of injecting an organic carbon source such as methanol or injecting some high concentration livestock waste, there is an economic problem when using an external carbon source such as methanol. The water quality after a treatment may fall.

In order to prevent this, a method of using organic liver (mainly acetic acid) generated by fermenting high concentration livestock wastewater or sludge anaerobicly around 30 ~ 36 ℃ can be used.In this case, fuel cost required for heating to maintain water temperature is required. Economic problems arise.

The present invention is to solve this problem is to use a part of the sludge after centrifugation in the anaerobic state to produce an organic acid and heat generated in the microbial reactor 12 as a heat source for maintaining the temperature required.

Sludge after centrifugation in most cases has a higher C / N ratio than the original livestock wastewater because organic nitrogen is separated into sludge and removed and biologically oxidizable ammonia nitrogen is separated after the flocculation agent is used in the centrifuge. It remains dissolved in the livestock wastewater, and since the ratio of ammonia nitrogen generally accounts for 30 to 60%, the nitrogen content ratio of the separated sludge is lowered by that amount.

For this reason, the C / N ratio of the sludge separated is about 7 ~ 8: 1, which is maintained at a very high ratio. Relatively less sludge is required than when using waste water.

A part of the separated sludge (5) is mixed with water in a sludge dissolution tank (6) equipped with a stirrer and completely dissolved to adjust the BOD concentration to about 30,000 to 60,000 mg / l, and then transferred to an organic acid fermentation tank (7) to about 15 to When the fermentation is carried out for 2 to 3 days in an anaerobic state while maintaining the temperature at 30 ° C., organic acids (mainly acetic acid) are generated while the organic matter is fermented. The acetic acid shows a high organic acid production rate near 15 ° C. and around 30 to 35 ° C.

Therefore, the temperature of the organic acid fermentation tank 7 was operated at 15 ° C. in winter and 30 ° C. in winter, but the water temperature was low in winter so that a large amount of heat was required to heat the temperature to 30 ° C. This is because there is a problem in terms of temperature, and in summer, the water temperature is high, so even if a little heat is applied, the required temperature can be maintained.

However, circulating a large amount of wastewater in the secondary C / N ratio adjustment tank 17 is not impossible to operate at 30 ℃ throughout the year and may be operated in this way.

The mixed solution in the microbial reactor 12 maintains a relatively high temperature of 30 to 38 ° C. throughout the year in most treatment plants due to the heat generated when microorganisms decompose organic matters. As a heat source for properly maintaining the temperature of the organic acid fermentation tank 7, the wastewater of the secondary C / N ratio adjustment tank 17 having a similar temperature is used because the heat generated in the microorganism reaction tank 12 is used. The circulating pump (7-1) is used to circulate the heat exchanger (7-2) integrally installed in the microbial reaction tank organic acid fermentation tank (7) to transfer the heat of the waste water to the organic acid fermentation tank (7) having a relatively low temperature. To maintain the required temperature.

The organic acid fermented in the organic acid fermentation tank (7) is mixed with a large amount of undissolved sludge and solids, which can increase the pollutant load and interfere with the microbial treatment when introduced into the microorganism reactor 12, the organic acid separation device In (8), the sludge and the organic acid are separated, and a part of the sludge is returned to the organic acid fermentation tank 7 for reuse, and the rest is returned to the livestock wastewater adjustment tank 3.

The organic acid separated in the organic acid separator 8 is transferred to the C / N ratio adjusting tank 11 by the transfer pump 1 (9), and the amount of the transfer is transferred to the C / N ratio suitable for biological denitrification.

The microbial reactor 12 needs to maintain anaerobic and aerobic conditions. To this end, a batch reactor or an anaerobic reactor and an aerobic reactor can be used. The organic matter is removed in the aerobic process. And ammonium nitrogen is oxidized to nitric acid.

In anaerobic processes, nitric acid is separated and removed by the action of denitrifying bacteria, and at the same time, some of the organic matter is removed.

In this process, the wastewater with the C / N ratio properly adjusted with organic acids is more denitrified than the wastewater with the C / N ratio properly adjusted with the livestock waste water itself, and the water quality after purification is excellent because the organic acid is It is because it is easy to use and denitrification reaction rate is faster than livestock wastewater, and during the fermentation process of organic acid, the decomposable substance is decomposed in a considerable amount or changed in its properties.

The livestock wastewater purified in the microbial reaction tank 12 is transferred to the coagulation reaction device 14 by the treated water transfer pump 13, where the coagulation reaction is carried out to the solid-liquid separation device 15, and separated into supernatant and sludge. The sludge is dewatered and disposed of in the dehydrator 16 and the supernatant is transferred to the secondary C / N ratio adjustment tank 17 for temporary storage and transfer of organic acid from the organic acid separator (8) so as to have an appropriate C / N ratio. Transfer the required amount to) and mix.

The wastewater mixed with the supernatant and organic acid is passed through the anaerobic biofilter 20 and the aerobic biofilter 21, which are the next stages, and the surface of the relatively coarse (about 3 to 5 mm) particle-shaped filter medium in the biofilter. It is purified by microorganisms that inhabit.

In the purification process, as in the microbial reaction tank 12, the anaerobic process removes nitrogen and removes some of organic matter, and in the aerobic process, nitrification of ammonia nitrogen and decomposition removal of organic matter occur.

The biofilter can hold the maximum amount of microorganisms among the microorganisms currently developed in a small volume so that it can stably maintain long SRT and low F / M ratio and pass through the biofilter layer. It is possible to increase the flow rate of wastewater, and the hydraulic retention time is short, so there is almost no decrease in water temperature, so it is possible to maintain about 20 ~ 25 ℃, which is the temperature at which low-temperature microorganisms grow, even in winter. It is most suitable as a two-stage treatment system of wastewater.

In order to enhance the denitrification effect, a part of the nitrified wastewater from the aerobic biofiltration unit 21 is returned to the anaerobic biofiltration unit 20, and depending on the nitrogen removal rate aimed at the return ratio, it returns approximately 100 to 300% of the influent amount. do.

In addition to the removal and purification of organic matter and nutrient salts by biological reaction, the biofiltration device has a physical filtration function by filter media, and the wastewater after purification has a very low ratio of SS components.

The wastewater purified by the biofiltration system goes through the ozone ultraviolet disinfection device (23), which is the next process, and removes coliform bacteria mainly from the wastewater by the action of ultraviolet rays and ozone, and also decomposes and removes some hardly decomposable substances into the discharge water. Discharged.

In the present invention, in treating livestock wastewater, a part of the sludge separated in the pretreatment process is heated to a temperature suitable for generating organic acids by using a microorganism reactor in an anaerobic state, so that organic acids are generated. It does not need external fuel and uses organic acid generated from sludge as organic carbon source for denitrification process of microorganism, so it does not need organic carbon source from outside, so it is very economical. There is a cleaner effect.

Claims (1)

A livestock wastewater adjusting tank for storing the livestock wastewater removed for a certain period of time, and a debris removal device for removing contaminants of livestock wastewater; Abandoning the livestock wastewater adjusting tank with air for at least 7 days to alleviate the toxicity of disinfectants such as livestock wastewater and equalize the quality; A centrifugal separator for separating the wastewater and sludge from the wastewater of the livestock wastewater adjusting tank and a device for storing the removed sludge; A portion of the stored sludge is mixed with a high temperature microbial treated wastewater in a secondary C / N ratio adjustment tank and some fresh water for temperature control to dissolve and homogenize a solution of sludge dissolution tank and sludge dissolution tank at anaerobic temperature. A solid-liquid separator for separating organic acids and solids from the fermentation liquid of the organic acid fermentation tank and the organic acid fermentation tank, and a heat exchanger for heating the organic waste fermentation tank while circulating the treated wastewater of the secondary C / N ratio adjustment tank at the rear end of the microbial reactor. Organic acid fermentation process and apparatus configured; A process and apparatus for appropriately adjusting the C / N ratio in a C / N ratio adjusting tank by mixing the livestock wastewater separated by the centrifuge at a predetermined ratio with the organic acid produced in the organic acid fermentation tank; A microbial reaction process and apparatus for cross-repeating anaerobic and aerobic treatment of wastewater transferred from the C / N ratio adjusting tank using microorganisms in a microbial reaction tank or purifying organic matter and nutrients using a separate treatment tank; A solid-liquid separation process and apparatus for solid-liquid separation and sludge dewatering of the treated water transferred from the microbial reaction tank through an agglomeration reaction in an agglomeration reactor; A C / N ratio adjustment process and apparatus for mixing the organic water produced in the organic acid fermentation tank at a predetermined ratio in the second C / N ratio adjustment tank to the treated water that has undergone the flocculation reaction; A process and apparatus for removing organic matter and nutrients from the two-step microbial reactor comprising the anaerobic biofiltration apparatus and the aerobic biofiltration apparatus for the wastewater that has undergone the C / N ratio adjustment process; And Livestock wastewater treatment apparatus and process comprising the step of removing the bacteria and residual organic matter in the wastewater by using ozone and ultraviolet light while passing the wastewater treated in the process.