KR100467336B1 - Advanced treatment apparaters and method of sewage water by flow distribution ratio. - Google Patents

Abstract

The present invention relates to an advanced treatment apparatus and method for highly removing nitrogen and phosphorus in sewage or wastewater by biological treatment method by predominantly prescribing specific microorganisms for each process in a sewage treatment plant or wastewater treatment plant and precisely establishing the necessary conditions.

The present invention utilizes different growth and growth conditions of microorganisms involved in anaerobic and aerobic and denitrification and uses submerged biofilm devices to achieve mass retention by predominantly attaching and attaching specific microorganisms and accurately maintaining the required nitrification rate. It is to effectively remove nutrients such as organic matter and nitrogen, and to obtain stable treated water quality even if the sewage inflow flow rate is changed by the sludge replenishment device and operation sequence water control.

To this end, an anaerobic tank is installed at the front of the process, and a submerged biofilm device is installed to mass-proliferate microorganisms suitable for anaerobic conditions to remove organic matter in anaerobic state, and then, an aerobic tank is installed to supply air and remove residual organic matter. And oxidize the ammonia and organic nitrogen in the sewage to nitrous acid, but about 56% of the sewage from the first anaerobic tank flows into the aerobic tank and about 44% is sent directly to the anaerobic denitrification tank installed after the aerobic tank. 56% of the ammonia in water is completely oxidized to nitrous acid. In the next anaerobic denitrification tank, a submerged biofilm is installed to mass-proliferate microorganisms suitable for anaerobic depletion of organic matter, converting ammonia and nitrite directly to nitrogen gas to remove most nitrogen, and NO₃) is denitrified in the anaerobic tank by internal return, and the sludge of the final sedimentation basin is returned to the anaerobic tank to maintain the required MLSS. It is an advanced treatment apparatus and method for treating sewage, which oxidizes and maintains ammonia as nitrous acid easily, accurately and stably, and also provides organic substances in sewage with lower C / N ratio and nutritional substances such as nitrogen and phosphorus. Can be removed effectively and the transportation cost and air supply amount is small This reduces the energy costs required for the treatment, eliminates the odor of the sludge and eliminates the odor, and provides stable discharge water quality against fluctuations in the influent sewage.

Description

Advanced treatment apparaters and method of sewage water by flow distribution ratio.

The present invention relates to an advanced sewage treatment method and apparatus for effectively removing nutrients such as nitrogen and phosphorus together with organic matter in a water treatment process using microorganisms such as a sewage treatment plant or a wastewater treatment plant.

As a method of removing organic substances, nitrogen, and phosphorus from sewage, there is a conventional method of treating sewage using anaerobic and aerobic tanks to perform denitrification and nitrification. In recent years, the process conditions are controlled so that specific microorganisms become dominant species. The treatment method is also used, such as domestic patent 10-0203050 (1999.3.22) or 10-276096 (2000.9.26).

In this method, in order to cultivate bacteria in Bacillus as dominant species, the aerobic conditions are maintained at the front stage of the process, and anaerobic and unaerobic conditions are returned at the end of the process, and the sludge is returned. Dominates.

The introduction technology of A₂ / O, which is a traditional advanced treatment method, is a method of denitrification after nitrification. An anaerobic denitrification tank is installed at the front end of the treatment process, and an aerobic aeration tank is installed at the rear end, and a large amount of mixed solution is returned after nitrification to anaerobic denitrification of the shear. Nitrogen denitrification (this method is called pre-nitrification).

However, in such a conventional method, it is difficult to dominate only bacteria of Bacillus, and it is economically burdened by the use of artificial microorganisms, which are inadequately controlled and expensive, and there is a limit in the dominance rate of bacteria of Bacillus and denitrification is in Bacillus genus. The effect was limited because it was not only caused by bacteria, and in the conventional high-treatment method, the denitrification effect was low in the case of sewage with low C / N ratio, such as lower nitrification rate at low water temperature and sewage inflow quality of most sewage treatment plants in Korea. Even if there is a problem and the C / N ratio is high, a large amount of internal return water (typically 300 to 400% of the influent sewage) is required to increase the denitrification effect. There was a problem in that the number of conveying equipment is required to increase the conveying equipment and power costs.

In addition, since the second half of the sewage treatment plant has been mandated by the Ministry of Environment since the second half of 2001, the secondary sewage treatment and the advanced treatment are mandatory. Was very severe, there was a problem that the water quality of the treated effluent is unstable according to the inflow flow.

In order to solve such a problem, there was a prior patent application No. 10-2002-0049341 and No. 10-2002-0060770 of the present invention, but 56% of the ammonia in the influent sewage is nitrous acid as the main technology of the process. However, it was difficult to maintain the ratio of nitrite correctly in response to changes in sewage inflow and water quality.

The technical problem to be achieved by the present invention consists of anaerobic and aerobic parts of the sewage treatment process, the bacterium acting in the advanced treatment of various kinds of sewage, such as Bacillus, Sedonas, independent nutrient bacteria using hydrogen is appropriate for each predetermined process during the treatment process. Maintain conditions, predominantly, and influent sewage is injected into the aerobic tank about 56% and anaerobic denitrification tank to inject about 56% of the total ammonia to nitrous acid (NO₂) to maintain a stable ammonia in the anaerobic denitrification tank And nitrogen gas conversion of nitrous acid and anaerobic denitrification by some organics, which can effectively remove nutrients and organics such as nitrogen and phosphorus even in low C / N ratio sewage without the use of special microbial culture agent and small internal conveyance. To keep the discharge quality stable even if the sewage inflow changes by time of day. It is to provide a method and apparatus for advanced treatment of sewage.

1 is a schematic diagram showing a configuration of the present invention

2 is a plan view showing the configuration of the present invention

Figure 3 shows the growth rate of nitrifying bacteria

Explanation of symbols for important parts of the drawings

1. Sewage Inflow Pipe 1-1. Inflow flowmeter 2. inflow sluice 3. anaerobic tank

4. Submerged Biofilm Device

5. Ratio Distribution 6. ORP Meter 7. Unit 1 7-1. Inflow Gate

8. diffuser 1 9. DO measuring instrument 10. 2nd aerodrome 11. diffuser 2

12. DO meter 13. Agitator 14. Anaerobic denitrification tank 14-1. Inflow Gate

15. Submerged Biofilm Apparatus 16. ORP Meter 17. Unit 3

18. Air diffuser 3 19. DO meter 20. Final sedimentation basin

21. Internal return piping 22. Internal return pump 23. Internal return flow meter

24. Sludge drawing piping 25. Sludge conveying pump 26. Sludge conveying piping

27. Sludge Return Flow Meter 28. Sludge Transfer Pump

29. Sludge Storage Tank 30. Sludge Filling Pipe 31. Sludge Filling Pump

32. Supplemental sludge flowmeter 33. Phase contrast microscope 34. Process control panel

35. Surplus sludge piping 36. Surplus sludge pump 37. Surplus sludge flowmeter

38. Surplus sludge thickener 39. Surplus concentrated sludge reservoir

end. Pretreatment unit; C) the inflow distribution; D. Discharge channel

The present invention to achieve the above technical problem,

The front anaerobic tank into which the pretreated sewage with debris and sand is removed, and the submerged biofilm unit is installed and kept anaerobic, decomposing organic matter in the anaerobic state and denitrifying some lines;

A first aerobic tank for discarding some of the sewage introduced from the anaerobic tank by an aerobic device to maintain aerobic and remove residual organic matter;

A second tank for oxidizing the ammonia in the sewage to nitrous acid (NO 2) while maintaining the dissolved oxygen concentration in a specific range by introducing the sewage flowing out of the first tank;

An anaerobic denitrification tank, in which an immersion type biofilm device is installed and maintained under anaerobic or anoxic conditions, and is mainly denitrified by directly converting ammonia and nitrous acid into nitrogen gas;

A distribution channel capable of introducing about 56% of the sewage flowing out of the foremost anaerobic tank and about 44% into the anaerobic denitrification tank;

A third tank for maintaining the sewage flowing out of the anaerobic denitrification tank to oxidize and remove residual pollutants and to oxidize untreated ammonia (NH₄-N) to nitrous acid or nitric acid in the previous step;

A final sedimentation basin separating sewage solids and symbolic water from the third vessel;

An internal conveying device for conveying the sludge to the anaerobic tank at the rear end of the third tank and a sludge conveying device for conveying the sludge of the final settler to the anaerobic tank and the first tank of the front;

Sewage diffuser configured to control the aeration amount in order to maintain the dissolved oxygen concentration within an appropriate range so that ammonia in the second tank can be oxidized and maintained as nitrous acid (NO2);

A second apparatus for installing an air diffuser and an agitator to maintain a complete mixing condition even when the amount of air is low;

A sludge storage tank and a sludge refilling device capable of replenishing and supplying sludge to the first vessel according to the needs of the process;

In order to maintain the required F / M ratio and SRT even when the flow rate fluctuates, each reactor acts as a set of reactors in a series direction and is blocked in parallel to each other in a series of independent series. The series of is connected to the common distribution channel, and the inlet of the anaerobic tank in front of each series is equipped with an electric inflow gate to calculate the number of series of reactors that operate automatically according to the inflow flow. A method and apparatus for controlling the number of driving sequences to control; And

Each reactor includes a flow meter and a measuring instrument necessary to measure ORP, DO, MLSS, etc., as well as a process control panel that automatically controls each process based on the measurement information. It provides an advanced treatment system and method for sewage to check the identification from time to time to maintain optimal process conditions.

Hereinafter, the present invention will be described in detail as follows, but the scope of the present invention is not limited to the following examples, but numerous modifications are possible, but in view of the contents of the present invention, the similarity or contradiction to the concept violates the rights of the present invention. do.

An embodiment of the present invention is as follows.

After sewage pipes enter sewage treatment plant, sewage and sand are removed from the pretreatment unit, and then the sewage inlet pipe (1) and inflow flow meter (1-1) are distributed evenly by several series in the distribution channel (B). ORP measuring instrument to enter the anaerobic tank (3) in the front through the inflow gate (2), and to install the submerged biofilm device (4) in the anaerobic tank (3) and to measure the anaerobic degree of the mixed liquid in the anaerobic tank (3) (6) was installed.

A ratio distribution channel (5) is installed at the rear end of the anaerobic tank (3), and the effluent of the anaerobic tank (3) passes through the inflow gate (7-1) of the first tank (7) installed at the rear end of the anaerobic tank (3). About 56% of the effluent was flowed in. The lower part of the first vessel (7) was equipped with an air conditioner (1) for adjusting the air supply amount and a DO measuring instrument (9) for measuring the dissolved oxygen concentration of the mixed liquid. Installed.

The second unit 10 is connected to the rear end of the first unit (7) and installed in the lower portion of the second unit 10 is installed air diffuser 2 (11) to adjust the air supply amount and the mixed liquid in the appropriate position in the middle A stirrer 13 was installed to stir the water and a DO meter 12 was installed to measure the dissolved oxygen concentration of the mixed liquid.

The anaerobic denitrification tank 14 was connected to the rear end of the second tank 10 and installed on the front side of the anaerobic denitrification tank 14 to install the inlet gate 14-1 connected to the ratio distribution channel 5 to the anaerobic tank ( About 44% of the sewage discharged from 3) was introduced, and at the same time, the total amount of sewage from the second tank was introduced.

In the anaerobic denitrification tank 14, an immersion type biofilm device 15 was installed, and an ORP measuring device 16 for measuring the anaerobic degree of the mixed solution was installed.

At the rear end of the anaerobic denitrification tank 14, the 3rd tank 17 was connected and installed, and the lower part of the 3rd tank 17 was installed with an aerator 3 (18) to supply air for maintaining aerobic. DO meter 19 for measuring the concentration was installed.

The final sedimentation basin (20) was installed at the rear end of the third basin (17), and a portion of the mixed liquid from the third basin (17) was introduced into the final settler, and the sludge precipitated in the final sedimentation basin (20) was the sludge drawing pipe (24). ), And the symbolic water was discharged through the next common discharge channel.

Part of the mixed liquid from the third tank 17 is divided into the internal conveying pump 22 through the inner conveying pipe 21 installed to be connected to the common water channel (C) installed at the rear end of the third bath 17. It was transferred to the drainage path (B) and installed to be conveyed to the inlet of the foremost anaerobic tank (3) through the inflow gate (2), and the inner conveying flowmeter (23) was installed in the middle of the inner conveying pipe (21).

The sludge precipitated in the final settling basin (20) was installed to be connected to the inlet of the anaerobic tank (3) and the first tank (7) installed sludge return pipe (26) branched from the sludge drawing pipe (24) The sludge conveying pump 25 was installed and transported, and a sludge conveying flowmeter 27 was installed in the middle of the sludge conveying pipe 26.

Part of the sludge precipitated in the final sedimentation basin 20 is to be transferred to the sludge storage tank 29 by the excess sludge conveying pump 28 installed in connection with the sludge drawing pipe 24 and the sludge of the sludge storage tank 29 is necessary. In order to supply the sludge to the inlet of the first tank (7), the sludge replenishment pipe (30) was connected between them, and the sludge replenishment pump (31) was transferred to the replenishment sludge flowmeter (32). Made it possible.

In order to remove the remaining sludge from the sludge stored in the sludge storage tank 29, the sludge storage tank 29 is connected between the excess sludge thickener 38 to the excess sludge pipe 35, and transferred to the excess sludge pump 36, and the excess sludge flowmeter The amount can be measured by (37).

The sludge concentrated in the excess sludge concentrator 38 is temporarily stored in the excess concentrated sludge storage tank 39 through a pipe to allow for dehydration.

A phase contrast microscope (33) was installed to identify the microorganisms in the sewage and treatment processes. The microorganisms of each process can be identified and information about the microorganisms in each process can be checked. The process control panel 34 was installed to allow automatic control.

Such action of the present invention is as follows.

Anaerobic microorganisms and aerobic microorganisms are used to remove organic substances and nutrients (mainly nitrogen and phosphorus) by microorganisms such as bacteria, and various kinds of aerobic and anaerobic microorganisms are used together in sewage treatment. Anaerobic microorganisms degrade slowly but produce less sludge after treatment, while aerobic microorganisms degrade faster than sludge.

Aerobic microorganisms can be divided into absolute aerobic and breathable anaerobic microorganisms, but absolute aerobic microorganisms require oxygen for growth and growth, so proliferation and growth is impossible without oxygen, and aerobic microorganisms can grow without oxygen and proliferate with oxygen. It is a microorganism that grows better.

Anaerobic microorganisms can be divided into oxygen-resistant and absolute anaerobic. Absolute anaerobic microorganisms are killed when oxygen exists, and oxygen-resistant microorganisms can grow and grow even with oxygen.

In addition, the removal of nitrogen, which is one of the nutrients, has been traditionally oxidized ammonia in water to nitric acid (NO₃) by the action of nitrifying bacteria in the aerobic state, and then reduced to nitrogen by the action of denitrifying bacteria in the anaerobic state. The traditional method of removing nitrogen by releasing nitrogen was a large amount of organic carbon sources for denitrification, which required a high C / N ratio (usually 8-12 times the ratio of organics and nitrogen).

However, some microorganisms are known to convert ammonia (NH₄-N) directly to nitrogen gas under anaerobic conditions using hydrogen or nitrous acid (NO₂) as a medium, and no organic carbon source is required in this process. Known.

For example, when nitrous acid (NO₂) is present in anaerobic conditions, it is known that hydrogen-containing autotrophic microorganisms (germs) exist that directly reduce ammonia (NH₄-N) to nitrogen gas without undergoing nitrification.

The denitrification process of this microorganism is expressed as follows.

As can be seen from the above equation, if nitrous acid (NO₂) is 1.26 / (1 + 1.26) = 0.557 = about 56% of the total nitrogen, ammonia (NH₄-N) is directly converted to nitrogen gas (N₂) and removed. Able to know.

Also, as already known, bacteria in Bacillus are capable of converting ammonia into nitrogen gas without denitrification and denitrification. In addition, denitrification occurs due to conversion of ammonia to nitrogen gas by unknown microorganisms. Nitrogen is also used for the substrate synthesis of microorganisms that grow in the air, and the nitrogen is removed by the excess sludge discharge that discards the remaining microorganisms.

Unlike so far, even in activated sludge processes that maintain only aerobic conditions, when the sludge residence time (SRT) is kept long and the DO concentration is kept relatively low, about 50 to 60% of nitrogen is removed. In addition to the nitrogen used for the synthesis of the substrate of the microorganism can be seen that a relatively large amount of nitrogen is removed by the action of microorganisms that are not well known in aerobic conditions.

The present invention utilizes the characteristics of the various microorganisms to remove such nitrogen to maximize the microbial retention and maximizing the specific microorganisms in a predetermined process by forming an environment and habitat suitable for the proliferation and growth of the various microorganisms, respectively It is to effectively remove organic matter and nitrogen and phosphorus.

In general, organic matters are known to be effective in aerobic removal, but a large amount of microorganisms grown by the method of the present invention have been shown to be capable of removing a large amount of organic matter (over 70% or more) without supplying oxygen in an anaerobic state. In the anaerobic tank (3) installed in the front of the process, the microorganisms are attached to the submerged biofilm device (4) to proliferate and grow, thereby selectively selecting anaerobic or communicable bacteria that have good growth and growth under anaerobic conditions rich in organic matter. Dominant and maximizing its retention to remove most of the organic matter in the sewage. The removal of organic matter in anaerobic conditions is partly removed by acid fermentation and methanation by anaerobic microorganisms (bacteria), and the remainder to the anaerobic microorganisms (bacteria) Is abundant in carbon dioxide (CO₂) and bicarbonate (HCO₃) Using a combination of oxygen is expected to remove the organic matter, while breathing.

In the first aeration tank (7), about 56% of the sewage from which most organic matter was removed from the anaerobic tank (3) flowed in to maintain a high MLSS concentration in aerobic conditions and a relatively low DO (dissolved oxygen) concentration (about 0.5 to 1.0 mg). / l), the remaining organic matter is removed by aerobic microorganisms (bacteria), and in the second vessel 10, the air supply is controlled according to the conditions to limit the dissolved oxygen concentration to a predetermined range of nitrifying bacteria. By action, the ammonia (NH (-N) in the sewage should be oxidized to nitrous acid (NO₂) and the nitrous acid should be kept as it is without being further oxidized to nitric acid (NO₃). In general, the concentration of dissolved oxygen is high and NO₂ The oxidation rate of nitrobacters, etc., oxidized to NO3, is faster than that of nitro sodium nitrate, which oxidizes ammonia to nitrous acid (NO2). In the aerobic condition NO₂ it is difficult to present. However, the minimum dissolved oxygen concentration required for the growth of nitrobacter is 0.68 mg / l and the minimum oxygen concentration required for the growth of nitrosomonas is 0.5 mg / l, so that the dissolved oxygen concentration of the second vessel 10 is 0.5 to 0.6. Nitrobacters that oxidize NO₂ to NO3 will not be able to grow if they remain constant at about mg / ℓ, so nitrosomonas can oxidize ammonia to NO₂ and maintain NO₂, and only 56% of the sewage inflow is treated. Therefore, the ammonia contained in the sewage is 56% of the amount of ammonia contained in the whole sewage, and this is oxidized to nitrous acid (NO2) at 1: 1, so that the amount of nitrous acid (NO₂) in the second tank 10 is 56% of the total ammonia amount. Thus, suitable conditions under which denitrification by Equation (1) can occur are formed.

In this case, the problem of keeping the dissolved oxygen concentration low is that the nitrification rate is about 0.5 times slower than that of the conventional denitrification process, which maintains the high dissolved oxygen concentration. Since it is about 0.56 times of ammonia, the amount to be nitrified is not a problem because it is almost similar.

In the anaerobic denitrification tank 14, 44% of the sewage flows directly from the anaerobic tank 3, and the remaining 56% is introduced from the second tank.

In this case, 44% of ammonia (NH₄-N) introduced from the anaerobic tank (3) and 56% of nitrous acid (NO₂) introduced from the second tank (10) exist in the anaerobic denitrification tank (14). Therefore, the ratio of ammonia and nitrous acid is 1: 1.26 as shown in Equation (1), so that the ideal conditions for denitrification are formed.

In the anaerobic denitrification tank 14, a submerged biofilm device 15 is installed to allow microorganisms to attach and proliferate and grow, thereby proliferating under anaerobic conditions in which organic carbon sources are low and ammonia and nitrous acid are present at an appropriate ratio. Microorganisms that grow well, for example, dominate the hydrogen-independent autotrophic bacteria that denitrate by converting ammonia directly into nitrogen gas and maximize its retention to remove ammonia and nitrogen from sewage as described in Equation (1) above. do.

This is because submerged biofilms can secure much more microorganisms than suspended growth reactors and maintain high microbial concentrations of about 15,000 to 30,000 mg / l based on MLSS concentrations.

Microorganisms that directly denitrify ammonia have been commonly used for proliferation and growth because they require long SRT, anaerobic conditions (oxygen deficiency), conditions that do not reduce the existing nitrite (organic depletion) and stable operation. Suspended growth method is impossible to dominate these microorganisms and increase their retention due to the lack of SRT and microbial load due to the microbial quantity limit, competition with other mixed microorganisms, and the change of MLSS concentration which changes frequently. The device can satisfy these conditions.

In addition, in the anaerobic denitrification tank 14, as described above, ammonia is directly converted to nitrogen gas for denitrification, and in the process, most of the nitrous acid is removed, and at the same time, the action of the denitrifying bacteria mixed in the sewage due to the presence of trace organic matter and anaerobic. As in the case of pre-denitrification, denitrification occurs as a minor amount of nitrous acid (NO₂) and part of nitric acid (NO₃) generated during the denitrification process are reduced to nitrogen gas.

In the above explanation, the reason why the percentage of sewage distribution ratio is indicated should be exactly 56%: 44% under ideal conditions, but the rate of oxidizing to nitrite by water temperature, water quality and quantity change is always 100%. This is because the distribution ratio must be adjusted for these variations with slight changes to the site conditions.

When the nitrogen removal effect of the present invention by the above formula (1) is calculated as follows.

In the above equation, one molecule of ammonia (NH₄-N) and 1.26 molecules of nitrous acid (NO₂) react to generate one nitrogen gas (N₂), 0.24NO₃, and 0.017 N of nitrogen as sludge. N is removed as sludge, and 0.24NO₃ is 100% of internal return ratio, so that half of that 0.12NO₃ is removed by gasifying with denitrification in the anaerobic tank (3), so the nitrogen removed is (2N + 0.017N + 0.12N = 2.137). N) can remove 2.137 ÷ 2.26 = 0.9455, or 94.5% of nitrogen from nitrogen (NH₄-N + 1.26NO₃ = 2.26N) in the sewage, and anaerobic denitrification effect by organic matter in the anaerobic denitrification tank (14). In consideration of this, it can be seen that more than 94.5% of nitrogen can be removed.

In addition, the amount of oxygen required for sewage treatment in the present invention can be calculated as follows.

The amount of oxygen required for sewage treatment is calculated by oxidizing the amount of oxygen required to oxidize 56% of the total ammonia present in the sewage to nitrous acid (NO₂) and the organic matter in the sewage (generally expressed as BOD). It can be seen as the sum of the amount of oxygen needed to remove.

The amount of oxygen needed to oxidize ammonia to nitrous acid can be obtained from the following equation.

According to Equation (2), 1.5 molecules of oxygen are required for one molecule of nitrogen for oxidation of ammonia to nitrous acid, and the molecular weight of nitrogen is 14 and the molecular weight of oxygen is 32, 1.5 × 32 ÷ 14 = 3.43, i.e., 3.43 times the amount of nitrogen in ammonia is required.

In general, it is known that about 1 mg of oxygen is required to remove 1 mg of organic matter (BOD).

Comparing the required amount of oxygen of the conventional pre-denitrification process with the present invention is as follows.

Conditions: BOD: 120 mg / l. T-N: 30 mg / ℓ (Since nitrogen in the influent sewage is mostly ammonia, see T-N = NH₄-N.)

In the traditional denitrification process, ammonia is first oxidized to nitric acid (NO₃), which requires 4.57 times the oxygen amount of ammonia and BOD of 3 times the amount of ammonia is removed without oxygen in anaerobic state. The amount of is equal to the amount of inflow BOD minus three times the amount of ammonia.

Therefore, the amount of oxygen required for the denitrification process is as follows.

(BOD-3 × T-N) × 1 + 4.57 × T-N = (120-30 × 3) × 1 + 4.57 × 30 = 167.1 mg / l

In the denitrification process according to the present invention, since 70% of the inflow BOD is removed in anaerobic state and only 56% of ammonia needs to be oxidized, the amount of oxygen required is as follows.

(Inflow BOD-inflow BOD × 0.7) × 1 + 0.56 × 3.435 × T-N = 36 + 56.5 = 93.7 mg / l

According to the above calculation results, it can be seen that the amount of oxygen required for organic matter removal and denitrification in the present invention is very small because only 56% of the amount of oxygen required for the conventional denitrification process is required.

The sewage treatment method of the present invention will be described in detail as follows.

The sewage from which fine contaminants and sand are removed in the pretreatment facility (a) is passed through the sewage inlet pipe (1) and the amount is measured in the inflow flowmeter (2) and then flows into the anaerobic tank (3).

Anaerobic tank (3) is maintained in the anaerobic state without oxygen supply, and submerged biofilm device (4) installed in the anaerobic tank (3), anaerobic bacteria and denitrifying bacteria, Bacillus (Bacillus) suitable for organic matter rich state over time As microorganisms such as anaerobic bacteria, such as aerobic bacteria, are attached, proliferate and grow, the amount increases and the equilibrium is maintained at a certain level, and the state is maintained and converted to MLSS concentration, which is 15,000 to 30,000mg / ℓ. Quantity can be retained.

The microorganisms attached in such a large amount decompose about 70% of organic matter in the sewage and denitrify at the same time to reduce nitric acid (NO₃) contained in the internal return water to release nitrogen gas to the atmosphere to remove nitrogen.

The ORP measuring apparatus 6 installed in the anaerobic tank 3 is a measuring instrument for judging whether the anaerobic degree of the anaerobic tank is appropriate. The appropriate ORP value is -150 to -300 mV.

The sewage through the anaerobic tank (3) flows through the ratio distribution channel (5), only 56% of the sewage flows to the first process (7), the next process, and the remaining 44% flows into the anaerobic denitrification tank (14).

The first aeration tank (7) is an organic substance remaining by the action of aerobic microorganisms in water while maintaining an aerobic state of dissolved oxygen concentration (DO) of 0.5 to 1.0 mg / l by supplying an appropriate amount of air by the aeration device 1 (8). And the MLSS concentration and DO concentration are controlled so that nitric acid or nitrous acid is not generated, and this sewage is transferred to the second process (10), which is the next process, and the second process (10) decomposes some organic matter and inflows into the sewage. Oxidizes ammonia and converts it into nitrous acid (NO2). In this process, it is very important to maintain the dissolved oxygen concentration (DO) at 0.5 to 0.6 mg / l. In some cases, the amount of supply may need to be reduced. At this time, due to the decrease in the amount of air, the mixing effect may not be achieved due to the decrease of the stirring force. Operating the agitator (13) thereby for.

The minimum dissolved oxygen concentration required for the growth of nitrosomonas, which is a nitrifying bacterium that causes nitrite (NO₂), is 0.5 mg / l, and the minimum dissolved oxygen concentration required for the growth of nitric oxide bacteria, such as nitrobacter, which produces nitric acid (NO₃) is 0.68 mg /. This is because the dissolved oxygen concentration must be maintained higher than 0.5 mg / l and lower than 0.68 mg / l so that the oxidized NO2 can be present without being further oxidized to NO2.

In the second vessel (10), it is important to change only about 56% of the total ammonia to nitrous acid according to the formula (1). Since only 56% of the total amount is introduced by the ratio distribution, the introduced ammonia is converted into nitrous acid. Only by% nitrification, this ratio is automatically obtained, so it is very easy to maintain the ratio of nitrous acid accurately, which can respond to fluctuations in flow rate and water quality to some extent, and thus obtain a stable treatment effect.

However, even in the first vessel (7), a small amount of ammonia is removed to some extent by the action of bacteria in Bacillus, and the ratio of ammonia to nitrite in the second vessel may not always be 100%. The amount of sewage produced is based on 56%, but to some extent, the inflow rate may be adjusted according to site conditions.

The sewage (about 56% of the total amount) passed through the second tank (10) and about 44% of the sewage flowed out of the anaerobic tank (3) together are transferred to the anaerobic denitrification tank (14), the anaerobic denitrification tank (14). Is maintained in anoxic or anaerobic state to satisfy the growth conditions of microorganisms required for direct denitrification, such as hydrogen-independent autotrophic bacteria, and almost all organic matter in the sewage is removed in the previous step, thus reducing nitrous acid even under anaerobic conditions. Due to this lack, heterotrophic bacteria are proliferated and their activity is reduced, so that hydrogen-independent nutrients are multiplyed into dominant species, and submerged biofilm devices (15) are installed as a means, and autotrophic bacteria using a large amount of hydrogen on the surface thereof. The growth and growth of nitrates by the action of these bacteria causes denitrification by direct nitrogen gas conversion of ammonia and the conversion of most of the nitrous acid to nitrogen gas in the process. Standing denitrification by most of the nitrogen is removed from here.

The sewage through the anaerobic denitrification tank (14) is transferred to the third tank (17) to remove residual contaminants in the aerobic state and nitrify some of the ammonia that may have been untreated. It is transferred to the inlet of the anaerobic tank 3 by the conveying pump 22, and the nitric acid (NO₃) generated in the denitrification process in the anaerobic denitrification tank 14 and the nitric acid generated in the third tank 17 by anaerobic conditions are anaerobic. The removal rate is reduced to nitrogen gas and the internal return ratio is based on about 100% of the inflow sewage, but the return ratio may be 0% if necessary, such as when the concentration of ammonia in the inflow sewage is low.

Phosphorus in the sewage is removed by removing excess phosphorus from the final settler (20) as excess sludge when a part of the phosphorus is used for the synthesis of the substrate of the microorganism and the excess of phosphorus is absorbed when changing from anaerobic to aerobic state in the third vessel (17). do.

The remaining portion of the sewage through the third vessel 17 is transferred to the final sedimentation basin 20, the sludge settles to the bottom and sinks, and the symbol water in the upper portion is discharged to the outside.

The sludge settled at the bottom of the final settling basin 20 is drawn through the sludge drawing pipe 24 and then part of the sludge conveying pipe 26 and the sludge conveying pump 25 as necessary through the inlet portion of the anaerobic tank (3). It is returned to the inlet of the first vessel (7) at about 20 to 100% of the flow rate and used to maintain an appropriate MLSS concentration.

There are various types of bacteria in this return sludge, which are grown in the reaction tank of the process described above that are suitable for them, and are used to maintain the required MLSS concentration in the sewage. .

When the sludge becomes excessive in the operating series, some sludge in the final sedimentation basin 20 is transferred to and stored in the sludge storage tank 29 by the excess sludge conveying pump 28 installed by being connected to the sludge drawing pipe 24 and the sludge storage tank ( Residual sludge other than the amount required in 29) is transferred to the excess sludge concentrator 38 by the excess sludge pump 36, concentrated to about 4%, and then transferred to the excess concentrated sludge storage tank 39 for temporary storage and then dewatering equipment. Dehydration treatment at

The sludge reservoir 29 should be kept in aerobic state to prevent the release of phosphorus.

In addition, among the combined sewage treatment systems that occupy most of our country, there is no flow control tank in the medium and large treatment plants, so that the inflow of sewage fluctuates greatly during the day and the discharge water quality also fluctuates.

Changes in inflow sewage are not constant for each location of the treatment plant, but in general it is excessively inflowed at 130-150% of the capacity during the day and 30-70% of the capacity at night. When operating in the daytime, the quality of the treated water deteriorates during the daytime and the microbial condition deteriorates due to the underload of the nighttime time, which affects the next daytime time again. In the process of the present invention, the ratio of nitrous acid is very important. If this occurs, the rate of nitrogen removal can be greatly reduced.

In the present invention, in order to solve this problem, the reactors from the anaerobic tank 3 of the treatment plant to the final settler 20 are arranged in one series in a series direction and are blocked from each other in a parallel direction so that these series are independently connected in parallel. After installation, install a common distribution channel (B) which penetrates each other at the front of several series, and install an inflow gate (2) that can be electrically operated remotely at the inlet of each anaerobic tank (3). Open the inlet sluice (2) by the required number to increase the number of series to operate, and if the inflow sewage is reduced, close the inflow sluice (2) as needed and program it to the process control panel 31 to reduce the number of series to operate. It is possible to determine the number of series driving with.

In addition, the capacity of inflow sewage and the number of operating series can be different, which is significant in small and medium sized sewage treatment plants.

If the operating conditions fluctuate, the amount of sludge present in the operating system is fixed, so even if the operation is carried out by changing the internal return ratio or sludge return ratio, it is often impossible to immediately maintain the required sludge concentration according to the changes. The sludge stored in the reservoir 29 (this sludge is a highly active sludge) is operated by the sludge replenishment pump 31 to convey the required amount of sludge to the first reactor 7 to maintain the required sludge concentration.

In addition, there are cases where excessive sludge exists in the operating series due to fluctuating operation conditions, resulting in a higher MLSS concentration than necessary. In this case, the sludge transfer pump 28 is operated to transfer and store the sludge in the sludge storage tank 29. Eliminate excess sludge in the series and prepare for lack of sludge in the operating series.

The volume of the sludge storage tank 29 is supplemented with sludge only until the inflow of sewage from the first vessel 7 to the third vessel 17 passes, and then the sludge required by the internal and sludge conveyance without additional sludge supplementation. Since the concentration can be maintained, the amount of sludge to be stored is determined.

Although there is some variation in size, the volume of the sludge storage tank is about 10-15% of the volume required when installing the flow regulating tank, which is more economical than the construction of the flow regulating tank.

In this way, even if the sewage inflow fluctuates, the proper load ratio (F / M ratio, BOD volume load, etc.) can be maintained at all times, improving the water treatment effect, stabilizing the discharge water quality, and maintaining the proper activity of microorganisms. The microorganisms of the land remain stationary for a while, but only about 6 to 8 hours of operation stops, and there is no problem in the operation of the process because no microorganisms are killed or weakened.

In addition, the influence of the deviation between the inflow sewage and the operating series may be partially mitigated by the action of microorganisms inhabiting the submerged biofilm devices installed in the anaerobic tank (3) and anaerobic denitrification tank (14).

Submerged biofilm devices installed in the anaerobic tank 3 and anaerobic denitrification tank 14 can be used in various ways, one embodiment is to use a rotary biofilm device (RBC).

The submerged rotary biofilm device is very effective because it can maintain the anaerobic state and at the same time can achieve microbial adhesion proliferation and complete mixing of sewage in the reaction vessel with one device.

In addition, the type of submerged rotary biofilm device may be a revolving or sponge-type rotary biofilm device having a large amount of microorganisms, rather than a conventional uneven plate type. It is good to consist of a biofilm of hydrophilic synthetic resin.

Another embodiment of the submerged biomembrane device is to use a fixed biofilm device such as a ciliated phase in combination with a stirring device for complete mixing in the reactor.

Another embodiment of the submerged biofilm device may use a granular biofilm-filled layer composed of granular material with a diameter of 3 to 5 mm, in which case the retention of microorganisms can be much higher than in the previous two examples. Although the volume can be very small, it is necessary to periodically wash the packed layer, which makes the maintenance slightly difficult. (The devices of the above examples are well known per se, so the specific structure is not shown.)

The phase contrast microscope 33 is attached with an enlarged screen so that process managers can directly check the status and identification of microorganisms so that they can immediately take effective measures necessary for process management, and the process control panel 34 provides various methods for optimizing treatment processes. The operating conditions are set to automatically control and operate various pumps and equipment according to predetermined conditions by receiving information from various flow meters and water quality data installed during the process.

In addition, the microorganisms used in the present invention are anaerobic and breathable anaerobic microorganisms predominantly do not rot easily even if the excess sludge is anaerobic, so there is almost no odor, and the smell from the concentrated sludge storage tank or influent sewage is removed by piping using a blower. If it is blown into the first tank (7), the microorganisms in the sewage decomposes the odor, so there is no need to install a separate odor removing device.

Another embodiment of the present invention is as follows.

The construction and function of the other embodiment of the present invention is the same as the above embodiment, but the ratio distribution channel 5 is installed in the first unit 7 and the rear end, and the introduced sewage is the first unit 7 through the anaerobic tank 3. And the outflow of the first vessel (7) flows into the ratio distribution channel (5), and then about 56% flows into the second vessel (10) and about 44% flows into the anaerobic denitrification tank (14). The outflow of the aerobic tank 10 was introduced into the anaerobic denitrification tank 14.

The operation of another embodiment of the present invention is the same as the above embodiment.

The present invention enables the microorganisms involved in the advanced treatment of sewage treatment plants or wastewater treatment plants to dominate according to the characteristics of each process, and the amount of sewage flowing into the first and the anaerobic denitrification tanks is about 56% to 44%. It is possible to keep the conditions suitable for denitrification accurately and easily stably by inflow to water, so it is highly efficient to remove organic matter and nutrients such as nitrogen and phosphorus without using special microbial activator, especially C / N like our country's sewage. High removal effect of organic matter and nutrients even in low sewage water, which improves discharge quality, protects the environment, has low internal return cost, and requires very little oxygen, so the cost of equipment needed for conveyance and oxygen supply is low, consumption power is reduced, and sewage inflow fluctuates. Water quality can be maintained stably and treatment of existing activated sludge process There is an effect that can be easily applied.

Claims (7)

The front anaerobic tank into which pretreated sewage with debris and sand has been removed, anaerobic decomposing organic matter and some pre-denitrification by installing and maintaining submerged biofilm devices; A first aerobic tank for discarding some of the sewage introduced from the anaerobic tank by an aerobic device to maintain aerobic and remove residual organic matter; A second vessel for oxidizing the ammonia in the sewage with nitrous acid (NO 2) while maintaining the dissolved oxygen concentration in a predetermined range of the sewage introduced from the first vessel; An anaerobic denitrification tank in which a part of the effluent of the second tank and an anaerobic tank are introduced together, and a submerged biofilm device is installed and maintained in anaerobic or anoxic conditions, and mainly denitrification is performed by directly converting ammonia and nitrous acid into nitrogen gas; A distribution channel capable of introducing about 56% of the sewage flowing out of the foremost anaerobic tank and about 44% into the anaerobic denitrification tank; A third tank for maintaining the sewage flowing out of the anaerobic denitrification tank to oxidize and remove residual pollutants and to oxidize untreated ammonia (NH₄-N) to nitrous acid or nitric acid in the previous step; A final sedimentation basin separating sewage solids and symbolic water from the third vessel; An internal conveying device for conveying the sludge to the anaerobic tank at the rear end of the third tank and a sludge conveying device for conveying the sludge of the final settler to the anaerobic tank and the first tank of the front; Sewage diffuser configured to control the aeration amount in order to maintain the dissolved oxygen concentration within an appropriate range so that ammonia in the second tank can be oxidized and maintained as nitrous acid (NO2); A second apparatus for installing an air diffuser and an agitator to maintain a complete mixing condition even when the amount of air is low; A sludge storage tank and a sludge refilling device capable of replenishing and supplying sludge to the first vessel according to the needs of the process; In order to maintain the required F / M ratio and SRT even when the flow rate fluctuates, each reactor acts as a set of reactors in the series direction and blocks them in parallel to form a series of independent units each in parallel. The series of is connected to the common distribution channel, and the inlet of the anaerobic tank in front of each series is equipped with an electric inflow gate to calculate the number of series of reactors that operate automatically according to the inflow flow. A method and apparatus for controlling the number of driving sequences to control; And Each reactor includes a flow meter and a measuring instrument necessary to measure ORP, DO, MLSS, etc., as well as a process control panel that automatically controls each process based on the measurement information. Advanced sewage treatment equipment to check the identification from time to time to maintain optimal process conditions. In claim 1, about 56% of the total ammonia is nitrated, and about 56% of the sewage from the anaerobic tank is introduced into the first tank, followed by the second tank, and about 44% of the sewage from the anaerobic tank and the second tank are The desalination by introducing the sewage from the anaerobic denitrification tank, but ammonia contained in the sewage introduced into the first tank is oxidized from the second tank to nitrous acid. In claim 1, about 56% of the total ammonia is nitrated, and the sewage from the anaerobic tank is introduced into the first tank, and about 56% of the sewage from the first tank is introduced into the second tank and the sewage from the first tank is About 44% of the sewage from the second tank is introduced into an anaerobic denitrification tank to denitrify, but the ammonia contained in the sewage introduced into the second tank is oxidized to nitrous acid. delete delete delete delete