JP5629448B2 - Wastewater treatment method - Google Patents

Description

The present invention relates to a nitrogen-containing wastewater treatment technique, and more particularly, wastewater that enables nitrification, autotrophic denitrification , heterotrophic denitrification , and removal of chemical oxygen demand to proceed simultaneously in the same reaction tank. It relates to a processing method.

Domestic wastewater, livestock and aquaculture wastewater, water leached from landfills and industrial wastewater contain large amounts of organic nitrogen and ammonia nitrogen. Nowadays, in the method of treating a nitrogen-containing waste water, as well as denitrification method organisms nitrification is generic to most industries, it is economical.

A conventional bionitrification denitrification reaction is as shown in FIG. First, the step of nitrification step is to ammonia organic nitrogen by the action of microorganisms, add water and decompose (depending on pH) to NH ₄ ⁺ or NH ₃ , followed by ammonia nitrogen (NH ₄ ⁺ -N) is oxidized to nitrite nitrogen (NO ₂ ^-- N), followed by oxidation of nitrite nitrogen to nitrate nitrogen (NO ₃ ^-- N). At this stage, oxygen is dissolved in water to provide electrons to ammonia nitrogen and nitrite, so that a large amount of energy is inevitable. Then step of denitrification stage, NO ₃ anaerobic heterotrophic denitrifying bacteria by metabolism of organic carbon sources ^- the NO ₂ ^- is reduced, followed by a continuous reduction in the N ₂ O and N _2, then the air Spread inside. However, general nitrogen-containing wastewater lacks organic carbon sources. It is necessary to add a carbon source from the outside in order to facilitate the action of denitrifying bacteria. In other words, denitrification method organisms nitrification consumes energy, not only get higher cost due to the need of adding a carbon source, a large amount of sludge in the progress of the denitrification reaction is deposited by heterotrophic bacteria Therefore, enormous sludge treatment costs are necessary. Also, since the nitrification and denitrification stages have different demands for oxygen dissolved in water, the industry must install different systems for aerobic nitrification and anaerobic denitrification . Therefore, economic efficiency is not so good.

Compared to the conventional methods described above, the anaerobic ammonia oxidation method (ANAMOX) has gradually developed and matured. For example U.S. Pat. No. 5,078,884 from NH ₄ ⁺ directly NO ₂ by the action of autotrophic denitrification bacteria under anaerobic environment ^- providing electrons to, removing total nitrogen in the water by generating a nitrogen In addition, when there is too much NH ₄ ^{+ in the} water and NO ₂ ⁻ is insufficient, a method of oxidizing a part of NH ₄ ⁺ to NO ₂ ⁻ and then proceeding with the above reaction was posted. However, since the oxidize NH ₄ ^+, must proceed under aerobic environment, the anaerobic ammonium oxidation method, NH ₄ ⁺ and NO ₂ ^- was to oxidize, NH ₄ ⁺ and NO ₂ ^- in It is necessary to install two or more systems to generate nitrogen, or to separately attach the microorganisms necessary for the two reactions to different intermediate materials. Therefore, this anaerobic ammonia oxidation method is expensive to install and not only has a high maintenance complexity, but also cannot remove the chemical oxygen demand in the soil and water.

US Pat. No. 5,078,884

The main object of the present invention is to provide a wastewater treatment method that allows heterotrophic denitrification , autotrophic denitrification and removal of chemical oxygen demand to proceed simultaneously. Among them, nitrification reaction, autotrophic denitrification reaction, heterotrophic denitrification reaction and removal of chemical oxygen demand can proceed in the same reaction tank.

In order to achieve the above-mentioned object, a wastewater treatment method capable of simultaneously proceeding autotrophic denitrification , heterotrophic denitrification and removal of chemical oxygen demand according to the present invention is performed in the same reaction vessel. In this process, the nitrification reaction, autotrophic denitrification reaction, heterotrophic denitrification reaction and removal of chemical oxygen demand are promoted while stirring work is performed by the action of microorganisms. Of which the microbe comprises nitrifying bacteria, the autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria. In the nitrification reaction, ammonia nitrogen is oxidized to nitrite nitrogen by the action of nitrifying bacteria. Autotrophic denitrification provides electrons from directly ammonium nitrogen to nitrite nitrogen by the action of autotrophic denitrifying bacteria to produce nitrogen and nitrate nitrogen. Heterotrophic denitrifying reaction consumes nitrate nitrogen and chemical oxygen demand by the action of heterotrophic denitrifying bacteria.

Autotrophic denitrifying bacteria can be anaerobic ammonium-oxidizing bacteria (Anaerobic ammonium oxidation bacteria). Anaerobic ammonia-oxidizing bacteria are classified as Plantomycins and are Latin-named gram-negative bacteria with the name Kuenenia stuttgartiansis. The deposit number at the Korean Collection for Type Cultures (KTCC) is KCTC 11551BP, and the deposit date is August 21, 2009.

  The above-described microorganisms can grow in suspension in the reaction tank. The reaction vessel can introduce oxygen and maintain the oxygen dissolution concentration between 0.1 and 0.5 mg / L.

It is a schematic diagram which shows the conventional denitrification reaction of bionitrification . 1 is a schematic diagram illustrating a wastewater treatment apparatus that allows autotrophic denitrification , heterotrophic denitrification , and removal of chemical oxygen demand to proceed simultaneously according to an embodiment of the present invention. The concentration change and removal efficiency of ammonia nitrogen in a wastewater treatment apparatus capable of simultaneously proceeding with autotrophic denitrification , heterotrophic denitrification , and removal of chemical oxygen demand according to an embodiment of the present invention. It is a schematic diagram which displays a percentage. The percentage change in COD concentration change and removal efficiency in a wastewater treatment method that allows simultaneous autotrophic denitrification , heterotrophic denitrification , and removal of chemical oxygen demand according to one embodiment of the present invention. It is a schematic diagram to display.

Wastewater treatment method according to the invention exhibits an effect by at least nitrifying bacteria, the action of autotrophic denitrification bacteria and heterotrophic denitrifying bacteria. Due to the them breeding in large quantities in wastewater treatment plants by nitrifying bacteria and any heterotrophic denitrifying bacteria conventional biological nitrification denitrification method, very easy to acquire. Although autotrophic denitrifying bacteria normally present in the water or activation sludge in nature, since the number is very small, it is necessary to culture. The present inventors have activated sludge inoculum, continuous stirred tank reactor wastewater treatment plant (Continuous Stirred Tank Reactor, CSTR) to create a culture environment for culturing autotrophic denitrification bacteria. By injecting wastewater containing a high concentration of ammonia nitrogen into the reactor during the culturing process and increasing oxygen dissolution by introducing air, the existing nitrifying bacteria in the reactor acquire electrons through oxygen dissolution, It is possible to proceed with the nitrification reaction and oxidize ammonia nitrogen to nitrite. If air is introduced, not only can nitrification be promoted, but also stirring power can be supplied. It is recommended that the oxygen dissolution concentration in water be maintained between 0.1 and 0.5 mg / L, more preferably 0.2 to 0.3 mg / L. Since the amount of air introduced is not very large, the concentration of dissolved oxygen in water does not clearly increase. Since ammonia nitrogen lacks oxygen dissolution during the nitrification process, only a partial nitrification reaction occurs. At this time, the nitrification reaction cannot be continued until it reaches the step of generating nitrate, and stops when it reaches the step of generating nitrite. Thus, if sufficient ammonia nitrogen and nitrite in water, autotrophic denitrifying bacteria allowed to proceed denitrification by ammonia nitrogen and nitrite, it is possible to grow. Third, the culture of autotrophic denitrifying bacteria After a lapse of four months to complete. Autotrophic denitrifying bacteria culture is completed are appraised as Kuenenia stuttgartiensis, and a gram negative bacterium classified in the plan transfected Streptomyces (Plantomycetes). The deposit number at Korean Collection for Type Cultures (KCTC) is KCTC 11551BP, and the deposit date is August 21, 2009. The autotrophic denitrification bacteria, to provide electrons from directly ammonia nitrogen into nitrite under anaerobic environment, it is possible to produce nitrogen and nitrate nitrogen causing the reaction.

Autotrophic denitrifying bacteria culture was completed, it is possible to proceed to purify the nitrogen-containing wastewater in the same reaction vessel with nitrifying bacteria and heterotrophic denitrifying bacteria. The wastewater treatment method according to the present invention includes a step of injecting water into a reaction tank to grow a mixture of various types of microorganisms, a step of introducing nitrogen-containing wastewater into the reaction tank, and discharging effluent water from the reaction tank; Advancing nitrification reaction, autotrophic denitrification reaction, heterotrophic denitrification reaction and removal of chemical oxygen demand simultaneously with stirring by the action of microorganisms in a single reaction vessel. Microorganisms of which comprises nitrifying bacteria, autotrophic denitrification bacteria, heterotrophic denitrifying bacteria.

Ammonia nitrogen in the nitrogen-containing wastewater undergoes a nitrification reaction by the action of nitrifying bacteria and the supply of oxygen, and is oxidized to nitrite nitrogen. Autotrophic denitrification provides electrons from directly ammonium nitrogen to nitrite nitrogen by the action of autotrophic denitrifying bacteria to produce nitrogen and nitrate nitrogen. Heterotrophic denitrification is exhausted nitrate nitrogen and chemical oxygen demand by the action of heterotrophic denitrifying bacteria, and to produce nitrogen. These reactions proceed uniformly by stirring simultaneously in the reaction vessel. By the above-described reaction, it is possible to reliably remove the ammonia nitrogen and chemical oxygen demand in the nitrogen-containing wastewater and achieve the purification purpose.

Nitrifying bacteria of which autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria uniformly suspended growth by being stirred in the reaction vessel. The above-described reaction is not limited to a continuous stirred tank reactor, and can proceed in a continuous batch reactor (SBR).

When the oxygen dissolution concentration in the system is 0.5 mg / L or less, the nitrification reaction by the nitrifying bacteria is insufficient, but the ammonia nitrogen in the system is sufficient, and the nitrite nitrogen is autotrophic denitrification. Since it is consumed quickly by the reaction, the nitrite nitrogen produced by the nitrification reaction is maintained at a relatively low concentration throughout. Therefore, it is possible to maintain the nitrification reaction in the system at a constant rate.

  Hereinafter, the structure and features of the present invention will be described based on the following embodiments. The present invention is not limited to the following embodiments, and can be implemented in various forms without departing from the spirit of the invention.

(First embodiment)
As shown in FIG. 2, the wastewater treatment apparatus 10 capable of simultaneously proceeding with autotrophic denitrification , heterotrophic denitrification and removal of chemical oxygen demand according to the present invention comprises a continuous stirred tank reactor ( And a reaction tank 12, microorganisms, a plurality of air sprayers 14, an air spray motor 16, and a sedimentation basin 18, and a continuous sterilized tank reactor (CSTR).

Microorganisms, nitrifying bacteria, include autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria, and uniformly suspended growth by being stirred in the reaction vessel 12. The air spreader 14 is disposed at the bottom of the reaction vessel 12. Since the air spraying motor 16 is connected to the air spraying device 14, it can transport air below the liquid level of the reaction tank 12 and increase the oxygen dissolution concentration. The sedimentation basin 18 is connected to the reaction tank 12. The air sprayer 14 and the air spray motor 16 can appropriately supply the oxygen necessary for the nitrification reaction, and can uniformly promote the reaction by providing stirring power.

  Nitrogen-containing wastewater awaiting treatment is directly introduced into the reaction tank 12, and after the reaction, it flows into the sedimentation basin 18 and precipitates suspended particulates. In the sedimentation basin 18, the upper layer liquid is discharged to the outside, and part of the sludge is returned to the reaction tank 12 by the pipe line 20. The wastewater treatment apparatus 10 has a hydraulic retention time (HRT) of 24 hours, a sludge retention time (SRT) of 18 days, and an oxygen dissolution concentration in water of 0.2 to 0.00. 3 mg / L. The contaminant concentration of the inflow water, the contaminant concentration of the effluent water, and the contaminant removal rate are as shown in FIGS. As shown in FIG. 3, the ammonia nitrogen concentration of the influent water is between 900 and 1100 mg-N / L. After being treated by the wastewater treatment apparatus, the ammonia nitrogen concentration of the effluent is between 44 and 208 mg-N / L, so that the ammonia nitrogen removal rate reaches 78 to 95%. As shown in FIG. 4, the chemical oxygen demand of the influent water is between 618 and 833 mg / L, and the chemical oxygen demand of the effluent is between 208 and 435 mg / L, so the removal rate is 46 Reaching 63%. That is, the wastewater treatment apparatus can simultaneously remove ammonia nitrogen and chemical oxygen demand in water.

(Second embodiment)
Similarly, when a continuous stirred tank reactor is adopted, HRT is set for 24 hours, SRT is set for 18 days, and the oxygen dissolution concentration in water is set between 0.2 and 0.3 mg / L, contamination of influent and effluent. The substance concentration is as follows.

This system has a total nitrogen removal rate of 49.2%. Of which 44.2% of the total nitrogen by the calculation results are reduced to nitrogen by the action of autotrophic denitrification bacteria, to diffuse into the atmosphere. The remaining 5% is diffused into the atmosphere by the action of heterotrophic denitrifying bacteria. For total nitrogen in wastewater is removed mainly by the action of autotrophic denitrification bacteria, wastewater treatment method according to the present invention as compared to conventional methods that rely only on the action of heterotrophic denitrifying bacteria, largely sludge amount It is possible to reduce the cost for the subsequent sludge treatment and to surely reduce the demand for organic carbon sources. The removal rate of chemical oxygen demand (COD) is 33.4%. 30.0% of them is consumed by heterotrophic denitrifying bacteria, the remaining 3.4% is consumed by another type of heterotrophic bacteria.

(Third embodiment)
When a continuous stirred tank reactor is used, HRT is set to 24 hours, SRT is set to 18 days, and the oxygen dissolution concentration of the water stream is set between 0.2 and 0.3 mg / L Is as follows.

This system has a total nitrogen removal rate of 60.9%. Of which 54.7% of the total nitrogen by the calculation results are reduced to nitrogen by the action of autotrophic denitrification bacteria, to diffuse into the atmosphere. The remaining 6.2% is diffused into the atmosphere by the action of heterotrophic denitrifying bacteria. The removal rate of COD is 42.9%. 19.7% of which is consumed by heterotrophic denitrifying bacteria, the remaining 23.2% is consumed by another type of heterotrophic bacteria.

The present invention, nitrification in the same reaction vessel, since it is possible to proceed autotrophic denitrification and heterotrophic denitrification, ammonium nitrogen in the nitrogen-containing waste water, nitrite nitrogen, It is possible to reliably remove nitrate nitrogen and chemical oxygen demand. Nitrifying bacteria, for autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria floating grown uniformly be stirred in the reaction vessel, or to install more than one reaction vessel, two used for accretion There is no need to provide these intermediate materials. Therefore, it is possible to reliably reduce the installation cost and simplify the operation and maintenance. Since many total nitrogen in waste water are removed by the action of autotrophic denitrifying bacteria present invention can greatly reduce the demand for sludge volume and the organic carbon source.

  10: Waste water treatment device, 12: Reaction tank, 14: Air distributor, 16: Air distribution motor, 18: Sedimentation basin, 20: Pipe line.

  KCTC 11551BP

Claims (4)

A wastewater treatment method capable of simultaneously proceeding with autotrophic denitrification, heterotrophic denitrification and removal of chemical oxygen demand,
Injecting water into the reaction vessel to mix and grow many types of microorganisms;
Introducing nitrogen-containing wastewater into the reaction vessel and discharging effluent from the reaction vessel;
Including simultaneously performing nitrification reaction, autotrophic denitrification reaction, heterotrophic denitrification reaction and removal of chemical oxygen demand while stirring work by the action of microorganisms in a single reaction tank,
Microorganisms, including nitrifying bacteria, Friday, August 21, 2009 with the Korean life Engineering Institute gene bank in the deposited deposit number KCTC 11551BP a is autotrophic denitrifying bacteria, and, the heterotrophic denitrifying bacteria,
The oxygen dissolution concentration in the reaction vessel is 0.1 to 0.5 mg / L,
The nitrification reaction oxidizes ammonia nitrogen to nitrite nitrogen by the action of nitrifying bacteria, and the autotrophic denitrification reaction provides electrons from ammonia nitrogen to nitrite nitrogen by the action of autotrophic denitrifying bacteria. A wastewater treatment method characterized in that nitrogen and nitrate nitrogen are produced, and the heterotrophic denitrification reaction consumes nitrate nitrogen and chemical oxygen demand by the action of heterotrophic denitrifying bacteria.   The wastewater treatment method according to claim 1, wherein the microorganisms grow in a floating state in the reaction tank.   The wastewater treatment method according to claim 1, wherein oxygen necessary for the nitrification reaction is introduced into the reaction tank.   2. The wastewater treatment method according to claim 1, wherein the nitrification reaction, autotrophic denitrification reaction, heterotrophic denitrification reaction, and removal of chemical oxygen demand proceed in the reaction tank by uniform stirring. .

Images