KR20020028410A - Nitrogen and phosphorus removal process from sewage and waste water by 2A/O RBC with internal settler - Google Patents

Abstract

PURPOSE: A system for removing nitrogen and phosphorus from sewage and wastewater by 2A/O RBC(Rotating Biological Contactor) with internal settlers, which is characterized in that by combining suspended growth process with hybrid biofilm process and employing internal sludge recycle, it is possible to reduce the site area required for the construction of wastewater treatment plant as well as achieve higher mass reduction rate of microorganism in comparison with conventional RBC processes. CONSTITUTION: Each of figures described in the drawing is defined as follows: raw wastewater(1), anaerobic basin(2), anoxic basin(3), primary aerobic basin, secondary aerobic basin(5, 6), anaerobic settler(7), anoxic settler(8), primary aerobic settler(9), secondary aerobic settler(10, 11), sludge recycle line(12, 13, 14), and sludge drainage(15). In this system as microorganisms related to biological phosphorus removal that is inferior to those concerned to nitrification show vigorous activities only under anaerobic condition, so the anaerobic settler is installed at the bottom of the anaerobic basin, which plays an important role not in primary sedimentation of raw wastewater, but also in the production of volatile fatty acid(VFA) by acid fermentation of organics. Volatile fatty acid, acting as electron donor, is a critical factor in microbial metabolism when performing biological phosphorus removal. In the secondary aerobic settler, luxury uptake of phosphorus by microorganism recycled from the anaerobic settler is induced.

Description

Nitrogen and phosphorus removal process from sewage and waste water by 2A / O RBC with internal settler}

In general, the purpose of wastewater treatment is to remove organic matter (COD, BOD) and suspended solids (SS). The general method of removing organic matter and suspended solids is to supply the organic matter in the water to the food of microorganisms and to sink in the water as the microorganisms ingesting the organic matter cling and increase in size. This sinking process is called precipitation. By removing the treated microorganisms to the outside, the removal of contaminants in the water is completed, and the microorganisms used are mainly aerobic microorganisms (Aerobic Bacteria).

Recently, however, due to lake or ocean eutrophication, it is required to remove nitrogen and phosphorus, which are the causative substances. It is done. Nitrogen removal uses two kinds of microorganisms, nitrifying bacteria and denitrifying bacteria. Nitrogen bacteria are aerobic microorganisms that combine ammonia nitrogen in water with oxygen to make nitric acid (NO ₃ ). Bacteria live using NO ₃ produced by nitrifiers instead of dissolved oxygen for their activity in the absence of dissolved oxygen. Oxygen in NO ₃ is used and N is left in water. N and N combine to form N _2, which becomes nitrogen gas and is released into the atmosphere. In other words, by removing the nitrogen component in the water to the nitrogen gas and blowing it into the air to remove the nitrogen in the water is completed.

Phosphorun Accumulating Organization (PAO) removal is performed by a special microorganism called PAO (Phosphorun Accumulating Organization), which is an arbitrary microorganism that can live under both anaerobic and aerobic conditions. Phosphorus Phosphorus is released into the body, and in aerobic conditions, the released phosphorus is taken up to synthesize ATP in the body. Precipitating and removing these microorganisms from water is the principle of biological removal of phosphorus. However, phosphorus-removing microorganisms are extremely sensitive to the surrounding environment, are inferior in food competitiveness to other microorganisms, and are difficult to cultivate in general wastewater treatment processes.

Among these wastewater treatment methods, there is Rotating Biological Contactors, which is a typical biological water treatment process that has been used for decades to remove organic matter from wastewater because of its high maintenance convenience and treatment reliability. It is capable of removing nitrogen, treating high concentrations of BOD at low concentrations, adapting well to impact loads, and having low power costs and easy operation.

Known biological treatment processes in the advanced treatment process for removing nitrogen and phosphorus include A2 / O method, modified Bandenpho method, University of Cape Town Process (UCT) method, Virgin Initiative Plant (VIP) method, etc. Both methods are treated separately from biological treatment and sedimentation tanks. On the other hand, Patent Publication No. 195-0008039 puts the purified organic acid into the biological treatment tank for shortening the treatment process, and Patent Publication No. 0167024 increases the aeration efficiency by using a mixed spinning machine as a method of increasing the efficiency of the biological treatment tank. , Patent Publication 10-0235250 also uses a multi-stage anoxic reactor, but biological treatment tank and sedimentation tank are operated separately.

The present invention is a newly devised process by improving the conventional rotational process (RBC) process used for removing organic substances to a high-treatment process. Recent waste and sewage treatments require the removal of nutrients such as nitrogen and phosphorus as well as organic substances due to eutrophication of rivers and lakes.In the existing RBC process, microorganisms must be returned due to the use of microorganisms attached to the original plates. Biological removal was impossible. Moreover, in the case of domestic sewage, the concentration of organic matter is relatively low, so it is difficult to remove biologically due to lack of VFA (Volatile Fatty Acid) which is essential for the growth of microorganisms when phosphorus is removed.

Particularly, microorganisms that remove nitrogen and phosphorus are suspended in the reaction tank, and there is a floating growth process that makes the microorganisms adhere to the media, and the attached growth process makes the microorganisms return and settle, Removal is easy and generally used, but a lot of professional personnel are required in the process of operating the process and there is a problem that can be exhibited a predetermined efficiency only if the operation is technically careful. Therefore, it is difficult to apply in small facilities requiring the reduction of operating cost.

On the other hand, in the growth process of attaching microorganisms to the media, there is almost no manpower for maintenance and automated operation is possible.However, because microorganisms are attached to the media, microorganisms that accumulate phosphorus from the water are precipitated, The biological removal that must be removed is a limitation of the processes developed so far.

The purpose of the present invention is to solve the problems of the prior art described above, by attaching a sedimentation basin inside the attachment microorganism process, especially RBC process, which is difficult to remove nitrogen, phosphorus to share the advantages of the attached microorganism and suspended microorganism process The invention was newly invented by modifying the existing RBC process to remove nitrogen and phosphorus as well as substances and suspended solids.

In addition, according to the present invention, a sedimentation basin was installed inside the process to facilitate operation and maintenance and to be biologically removed using the RBC process, which is an attached microorganism process, and thus, microorganisms can be returned and maintained accordingly. It is the first process that combines the attachment microbial process and the floating microbial process.

1 is a schematic diagram of a device for implementing a method for removing nitrogen and phosphorus in wastewater using a sedimentation basin attached anaerobic rotary disc method according to the present invention.

* Description of the symbols for the main parts of the drawings *

1: influent feed pipe 2: anaerobic tank

3: anaerobic tank 4: aerobic tank

5, 6: 2nd stage tank 7: Anaerobic tank bottom sedimentation tank

8: anoxic tank bottom settling tank 9: aerobic tank bottom settling tank

10, 11: sedimentation tank lower secondary tank 12: second aerobic tank return pipe

13: anaerobic tank return tube 14: anaerobic tank return tube

15: waste pipe

In order to achieve the object of the present invention as described above, the apparatus for the removal of nitrogen and phosphorus according to the present invention transforms the existing RBC process into an anaerobic tank, an anaerobic tank, an aerobic tank, a secondary tank of the RBC tank, as shown in Figure 1, A sedimentation tank was attached to the bottom of each reactor and internal transfer was carried out between anaerobic, anaerobic, and aerobic processes, thereby making it possible to remove biological nitrogen and phosphorus by utilizing the characteristics of both the attached microbial process and the floating microbial process. At this time, the RBC process requires the first and second sedimentation basin, and the function of the first and second sedimentation basin can be significantly reduced by performing the function in the inside of RBC.

In addition, the level of the tank is that all the tanks are open in the air so that they flow naturally due to gravity, and the pump is used only for conveyance.

The method for removing nitrogen and phosphorus from wastewater and wastewater using the anaerobic and aerobic rotating disc method according to the present invention and the apparatus thereof will be described in detail according to the accompanying drawings.

1 is a schematic diagram of a device for implementing the anaerobic, aerobic rotation disc method according to the present invention for the removal of nitrogen, wastewater, phosphorus in the drawing 2 is an anaerobic tank, 3 is an anaerobic tank, 4 is an aerobic tank, 5 and 6 are This is the second aerodrome. The lower part of each of these treatment tanks is characterized in that the settling tank is attached to the inside of the RBC, as shown in 7, 8, 9, 10, 11 in the figure.

The first influent is introduced into the anaerobic tank (2) without additional sedimentation process through the influent feed pipe (1), the suspended solids in the influent is precipitated in the lower anaerobic sedimentation tank (7) and the precipitated material has an acid fermentation process. Sedimentation tank (7) under the anaerobic tank increases the efficiency of biological removal by simultaneously acting as primary sedimentation basin and acid fermenter, while VFA (Volatile Fatty Acid) produced in acid fermentation tank is anoxic tank (3). Increasing the denitrification efficiency increases the efficiency of biological nitrogen removal.

In addition, the anaerobic tank of this process is slightly different from the anaerobic tank for methane (CH ₄ ) fermentation.In the anaerobic tank for methane fermentation, organic matter is decomposed into methane through organic acids, but in this process, it does not proceed to methane production. It only proceeds to organic acids. The reactor is therefore not enclosed and in contact with air and does not require a separate gas tank. The maintenance of anaerobic conditions is naturally achieved by the high concentration of organics entering the water and decomposing, which is further activated by the fermentation of the precipitated organics in the lower settler. In the present invention, the main purpose of the anaerobic reactor is to provide a food which is easily decomposed exclusively to the phosphorus-removing microorganism, and the characteristics of the phosphorus-removing microorganism have been used to achieve this purpose. Phosphorus-free microorganisms are the most inferior in competition for food compared to organics-free and nitrogen-free microorganisms. Therefore, in order for the phosphorus-removing microorganism to be exclusively fed, the organic matter-removing microorganism and the nitrogen-removing microorganism must create an environment in which they cannot live. The condition is anaerobic. Therefore, anaerobic conditions are created to exclusively supply phosphorus-removing microorganisms, and the phosphorus-removing microorganisms utilize organic acids generated by decomposition of anaerobic bacteria.

In addition, the water passed through the anaerobic tank is introduced into the anaerobic tank (3), the nitrogen nitrified by the microorganisms in the aerobic tank is released into the atmosphere as nitrogen gas through the reduction process and the organic material is further removed and then flowed into the aerobic tank (4). do. In the aerobic tank 4, organic matter is adsorbed and removed by RBCs by aerobic microorganisms, and sewage is purified by oxidation and purification, and inflow nitrogen causes nitrification.

The lower settling tank of the aerobic tank serves as a secondary settler for the detachment of adherent microorganisms, and also returns the microorganisms to the anaerobic tank to reduce biological microorganisms, thereby reducing the sludge production cost and reducing sludge treatment costs.

In addition, the nitrified treated water is returned to the anoxic tank 3 at 1 to 2 Q from the lower settling tanks 10 and 11 of the second aerobic tank via the second aerobic tank return pipe 12. The settling sludge of the anoxic tank is denitrified and then returned to the anaerobic tank 2 through the anoxic tank return pipe 13. The settling sludge of the anaerobic tank is returned back to the secondary aerobic tanks (5, 6) via the anaerobic tank return pipe (14), where phosphorus excess intake occurs, and the phosphorus excess intake microorganisms are finally passed through the waste pipe (15) Discard it.

As described above, according to the present invention, according to the present invention, a sedimentation basin attached anaerobic, aerobic rotation disc method, nitrogen, phosphorus removal apparatus using wastewater, and a sedimentation basin are installed in the process so that the microorganisms can be returned. Therefore, it is the first process that combines the attachment microbial process and the floating microbial process, which makes it possible to remove phosphorus even in easy-to-maintain attached microbial process. According to the present invention, by attaching a separate sedimentation basin which can be added to the general wastewater treatment process inside the RBC, it is possible to use the facility more efficiently and reduce the sludge treatment cost due to the reduction of the final sludge generation. It has an effect.

Claims (5)

Rotational disk method (RBC) process is transformed into anaerobic, anaerobic and aerobic RBC tanks to facilitate operation and maintenance and biological removal by attaching a settling tank at the bottom of each reactor to return internally between anaerobic, anaerobic and aerobic processes. Method for removing nitrogen and phosphorus from wastewater, wastewater by using the rotating disc method utilizing the characteristics of both adherent microbial and suspended microbial processes The nitrogen level of the wastewater according to claim 1, wherein the level of the tank is that all the tanks are exposed to air, flow by natural flow by gravity, and the pump is used only for conveying. , Phosphorus removal method The method for removing nitrogen and phosphorus from wastewater, wastewater using a rotating disc method according to claim 1, wherein the facility site is significantly reduced by performing the functions of the primary and secondary sedimentation basins in the RBC. The method according to claim 1, wherein the sedimentation basin under the anaerobic tank performs the role of an acid fermentation tank simultaneously with the role of the primary sedimentation basin to increase the efficiency of biological removal. How to remove The rotation of claim 1, wherein the sedimentation basin under the aerobic tank serves as a secondary sedimentation basin in preparation for detachment of adherent microorganisms, and also returns the microorganisms to the anaerobic tank to reduce biological microorganisms, thereby reducing the final sludge generation. Nitrogen and Phosphorus Removal from Wastewater by Disc Method