KR101828296B1 - Wastewater Processing Appliance using Existing Activated Sludge Appliance as Shortcut Nitrogen Removal Process - Google Patents

Abstract

A wastewater treatment apparatus comprises: a water treatment processing part removing soluble organic substances in primarily precipitated wastewater from a bioreactor and then carrying out solid-liquid separation; and a sludge treatment processing part concentrating solid-liquid separated solid, conducting anaerobic digestion, and carrying out solid-liquid separation using the solid. The water treatment processing part additionally includes an anaerobic ammonium oxidizing tank at a rear end of a solid-liquid separation part, and the bioreactor carrying out nitrozation on an effluent in a nitrous acid reactor as some of the bioreactors are used as the nitrous acid reactor. By applying and altering an existing treatment place into a process capable of carrying out shortcut biological nitrogen removal, it is possible to alter processes in an economical way. Compared to existing nitrogen removal processes, 65% of oxygen and 100% of external carbon sources are reduced.

Description

(Wastewater Treatment Appliance using Existing Activated Sludge Appliance as a Shortcut Nitrogen Removal Process)

The present invention relates to a wastewater treatment apparatus that can be used by changing an existing treatment plant, which is an activated sludge process, to a shortened nitrogen removal process. More particularly, The present invention relates to a wastewater treatment apparatus for removing nitrogen efficiently and economically by introducing the wastewater into a stable form.

Contaminants present in sewage and wastewater include solids, organic matter as well as nutrients such as nitrogen and phosphorus. Physical, biological and chemical methods are used to remove these contaminants. Among these methods, biologically activated sludge process that removes pollutants by using bacteria is most economically and efficiently used, and thus is most widely used in the field.

A general system for biologically removing organic matter consists of a water treatment facility and a sludge processing unit as shown in Fig. The water treatment process unit includes a first precipitation process (first preconditioning process) for removing particulate organic matter, a bioreactor that converts air into carbon dioxide by oxidizing the organic matter by supplying air to remove dissolved organic matter, And a secondary precipitation step (solid-liquid separation unit) for precipitating / separating the treated water and the microorganisms to ensure clean treated water. The sludge treatment process section comprises a concentrating section for increasing the solids concentration, an anaerobic digestion tank for anaerobic digesting the concentrated solids, and a dewatering section for solid-liquid separating the anaerobically digested solids, the step of treating the solids separated in the primary purifying section and the solid- .

In general, in the biological organic treatment process, organic matter is removed through the following reaction. As shown in the formula, it is necessary to supply oxygen as an electron acceptor. 30 ~ 50% of the total.

CH ₃ OH + O ₂ ? CO ₂ + 2H ₂ O

The sludge generated in the primary precipitation and solid-liquid separation process is treated in the sludge treatment facility. Generally, the solid (dehydrated cake) is collected through the concentration (concentrated portion) and the anaerobic digestion (anaerobic digestion tank) Was removed, and the desalted liquid was flowed back into the water treatment process without any additional treatment.

The water treatment process unit in a general method for biologically removing nitrogen and phosphorus employs a denitrification / nitrification reaction tank as a bioreactor in the system shown in FIG.

Removal of nitrogen in sewage and wastewater requires multiple steps of biological reactions. First, the reduced ammonia nitrogen should be oxidized to oxidized nitrogen by supplying air as in the following equation.

^{_{NH 4 + + 1.5O 2 → NO}} 2 - + 2H + + H 2 O

NO ₂ ^- + 0.5O ₂ → NO ₃ ^-

NH ₄ ⁺ + 2O ₂ → NO ₃ ^- + 2H ⁺ + H ₂ O

As can be seen from the equation, 3.43 mg of oxygen is required to oxidize 1 mg of ammoniac nitrogen to nitrite, and 1.14 mg of oxygen is further consumed to oxidize 1 mg of nitrite nitrogen to nitrate nitrogen. Thus, 1 mg of ammonia nitrogen is nitrated 4.57 mg of oxygen is needed to oxidize to nitrogen. The nitrogen concentration in the sewage is about 40 ~ 50mg / L, and the oxygen required to oxidize it is 182.8 ~ 228.5 mg / L, which is higher than the amount of oxygen required for organic matter oxidation, which causes the increase in the sewage treatment plant operation cost. The oxidized nitrate nitrogen is discharged into the atmosphere through the reaction as shown in the following equation to finally remove nitrogen. As a result, a large amount of oxygen and organic matter is required to biologically remove nitrogen, which results in an increase in operating costs.

NO ₃ ^- + 1.08 CH ₃ OH + 0.24H ₂ CO _{3 -} > 0.06C ₅ H ₇ O ₂ N + 0.47N ₂ + 1.68H ₂ O + HCO ₃ ^-

Sludge is also generated in the biological nitrogen / phosphorus removal process. Generally, when it is treated through concentration, anaerobic digestion, dehydration, the effluent generated at this time is treated by the water treatment process without any treatment. In general, the amount of reflux generated in the sludge treatment process including desalination is a small amount of 1 to 2% of the influent flow rate, but the load of nitrogen and phosphorus is 10 to 20% of the influent load, so that proper treatment is required.

Recently, in order to prevent global warming, efforts have been made to reduce energy consumption and carbon dioxide generation. Researches are being actively carried out to achieve this purpose in sewage treatment. Efforts are being made to produce methane, a useful energy source, by utilizing the organic matter present in wastewater.

In order to recover a large amount of methane, it is necessary to maximize the methane production using an anaerobic acid fermentation and methane fermentation microorganisms by introducing the organic substances present in the wastewater into the anaerobic process as much as possible. For this purpose, a coagulant is injected into the primary sedimentation tank or a process having a high solid removal effect such as a filtration process is introduced. In this case, a shortage of carbon source necessary for the subsequent nitrogen removal occurs and nitrogen load There are disadvantages.

The method developed to solve this problem is a simple nitrogen removal process in which ammonia nitrogen is oxidized only to the nitrite (NO ₂ ^- ) stage and then ammonia nitrogen is used as an electron donor to remove nitrogen through denitrification. This method has the advantage of saving 60% of oxygen and 100% of organic matter than the conventional method.

Despite these advantages, the single-stage nitrogen removal process is often used to limit the treatment of special wastewater or anaerobic digestion tank supernatant at sewage treatment plants. However, in recent years, various researchers have been making steady efforts to introduce them into the main treatment process of the sewage treatment plant.

The most important thing to introduce a single-stage nitrogen removal process into the main treatment process is to achieve stable nitrification. The nitrification water generated in the anaerobic digester of the sludge treatment process has a high ammonia nitrogen concentration of 1,000 mg / L and a high temperature of 25 ° C or higher, which can easily achieve nitrification. In this condition, the growth of Ammonia Oxidation Bacteria (AOB) is higher than that of Nitrite Oxidation Bacteria (NOB). However, in the case of the main treatment process, the ammonia concentration is as low as 30 to 50 mg / L and the water temperature is as low as 15 ° C or less. Therefore, it is difficult to secure the required nitrite in the short-axis nitrogen process because stable nitrite oxidation is not achieved.

In order to ignite the AOB more than NOB, it is known that the solids retention time should be less than 1 day because the Doubling Time of NOB is required more than 1 day. NOB can be washed out and the AOB can be dominated. However, it is possible to wash out the NOB by operating the SRT for less than 1 day. However, since the existing treatment plant plays a role in removing organic matter, a large amount of heterotrophic microorganisms is ignited. Therefore, AOB It is not technically easy to dominate. Generally, the heterotrophic microorganisms that perform organic removal are very short with a doubling time of 0.17 days. Therefore, heterotrophic microorganisms can not but be ignited even if SRT is operated for 1 day to ignite AOB. Therefore, it is necessary to solve the problem of igniting the AOB for the nitrification by using the reaction tank of the existing treatment plant, so that the shortening nitrogen removal process can be applied to the main treatment process.

In anaerobic conditions, the ammonia oxidation process by nitrite nitrogen (shortening nitrogen removal) is carried out by specific microorganisms. Since Anaerobic Ammonia Oxidation Organism which performs single short Nitrogen Removal reaction has a very short growth rate and a very long Doubling Time of 11 days, it is very important to apply a reactor that does not wash-out microorganisms in order to obtain stable microorganisms .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method and apparatus for removing nitrogen gas by stably obtaining nitrite and stably maintaining anaerobic ammonium oxidizing bacteria in the application of a single- .

Another object of the present invention is to provide a method for minimizing the remodeling cost and operating cost of a conventional treatment plant in applying a short-circuit nitrogen removal process using an existing treatment plant.

In order to accomplish the above object, the present invention provides a method for removing particulate organic matter from wastewater, comprising: a first step of removing particulate organic matter from wastewater, a bioreactor for removing dissolved organic matter from the first settled wastewater, A water treatment unit having a separation unit; An anaerobic digestion tank for anaerobic digesting the concentrated solids; and a dewatering unit for solid-liquid separating the anaerobically digested solids, wherein the sludge processing unit includes: Wherein the water treatment process unit further comprises an anaerobic ammonium oxidation vessel at the downstream end of the solid-liquid separation unit, wherein a part of the bioreactor is used as a nitrite reaction tank, and the nitrite reaction tank And the desolvation solution generated in the dehydration section is nitrified.

According to another aspect of the present invention, there is provided a method for removing particulate organic matter from wastewater, comprising: a first step of removing particulate organic matter from wastewater, a bioreactor for removing dissolved organic matter from wastewater that has been firstly precipitated, and a solid- A water treatment apparatus provided with the water treatment apparatus; An anaerobic digestion tank for anaerobic digesting the concentrated solids; and a dewatering unit for solid-liquid separating the anaerobically digested solids, wherein the sludge processing unit includes: Wherein the water treatment process unit further comprises an anaerobic ammonium oxidation tank at the downstream end of the solid-liquid separation unit, and the sludge treatment process unit includes a nitrification tank for nitrifying the desorption liquid at the downstream end of the dehydration unit, And the desolvation solution generated in the dewatering unit is nitrified and introduced into the anaerobic ammonium oxidation tank.

The solid-liquid separator may include a separation membrane.

It is preferable that the above-described anaerobic ammonium oxidation tank employs an adhering process.

A part of the effluent of the primary settling portion flows into the nitrification tank.

An adhering type filter material is used in the above-mentioned attachment process.

Through the present invention, it is possible to change the process economically if the process is changed to a process capable of removing the shortened nitrogen by utilizing the existing treatment plant. In particular, the existing primary treatment facility, solid-liquid separation process, and sludge treatment process are used without modification, so no additional cost is required. The bioreactor is used as an organic oxidation reaction tank and a nitrification tank. It does not require any facility change and can be changed economically because only the operation method of the process is changed. Some of the effluent tank can be used for CSO treatment, so it is possible to treat rainwater effluent without additional facilities.

According to the present invention, since nitrogen is removed through the single-stage nitrogen removal process, it is possible to reduce oxygen by 65% and external carbon source by 100% as compared with the conventional nitrogen removal process.

FIG. 1 is a view showing a conventional organic material removal process
FIG. 2 is a schematic view showing a single-shaft nitrogen removal process using an existing facility according to the present invention
FIG. 3 is a view showing an existing plant change concept map
FIG. 4 is a conceptual diagram of a conventional process for shortening the nitrogen removal process by adding a separate nitrification tank according to the present invention
FIG. 5 is a conceptual diagram of a conventional treatment plant alteration scheme in which a separate nitrification tank according to the present invention is introduced
FIG. 6 is a schematic view showing a modification concept of introducing the desalination solution according to the present invention into the anaerobic ammonium oxidation tank.
FIG. 7 is a conceptual diagram of an existing treatment plant change-over scheme for introducing the desalination solution according to the present invention into the anaerobic ammonium oxidation tank

The present invention proposes a method for effectively implementing a short-scale nitrogen removal process utilizing an existing treatment plant. To this end, the present invention utilizes an existing facility as shown in FIG. 1, and the system of the present invention is shown in FIG.

The wastewater elimination apparatus according to the present invention includes a water treatment (main treatment) purification unit including a primary purification unit, a biological reaction tank for oxidizing organic substances (nitrite reaction tank), a solid-liquid separation unit, and an anaerobic ammonium oxidation tank, and an enrichment unit, And a sludge treatment unit having a dehydration unit for treating the solid matter generated in the water treatment facility. 1, the system according to the present invention has a configuration in which the water treatment process part further comprises an anaerobic ammonium oxidation tank, and a part of the bioreactor is used as a nitrite tank as described later . This nitrite reaction tank is arranged in parallel with the remaining bioreactor.

First, the solid material in the influent water is separated from the existing treatment station primary treatment unit. The separated solids are introduced into the concentrating section in the sludge treatment facility. At this time, it is possible to utilize all of the existing treatment plant primary treatment facilities and additionally use flocculant to increase the solid removal efficiency.

The primary effluent from the primary treatment facility flows into the bioreactor, which is aeration tank of the existing treatment plant, and removes only organic matter through air injection. Only C / N ratio should be adjusted to 1 or less by quickly removing organic matter, so only a part (50%) of existing aeration tank is used.

(25%) of the aeration tank, which is the biological reactor of the existing treatment plant, and the amount of air supplied (DO <1.0 mg / L) and SRT (<1 day) to oxidize ammonia nitrogen to nitrite nitrogen by forming conditions under which AOB can be ignited.

Organics are removed from the bioreactor, and ammonia nitrogen is converted into nitrite in a nitrite reactor, which is a part of the bioreactor. Then, microorganisms and treated water are separated through solid-liquid separation at the solid-liquid separator. The solid-liquid separation process may utilize existing facilities such as sedimentation basin, and a separation membrane may be additionally used for stable solid-liquid separation.

The sewage having the solid-liquid separation flows into the anaerobic digestion tank (anaerobic ammonium oxidation tank), and the nitrogen is removed through the shortening nitrogen removal reaction. The single - shot nitrogen removal reaction can remove only 30 to 46% of the nitrogen present in the inflow sewage, because the nitrogen load in the recirculating water is 20 to 30% of the total nitrogen load, since nitrite and ammonia react at a ratio of 1: 1. In this case, 20 ~ 30% of energy can be saved compared with the case of removing 30 ~ 40% of nitrogen through the existing nitrogen removal process.

FIG. 3 shows the application of the concept of FIG. 2 to the treatment plant. In the case where the existing treatment plant reaction tank is four, 1 is used as the nitrite tank, 2 is used as the organic substance removal reaction tank, and the remaining 1 is used as the CSO treatment tank occurring during rainfall or as the anaerobic ammonium tank .

The effluent from the nitrification tank and the organic material removal tank flows into the anaerobic ammonium oxidation tank through the solid-liquid separation, and the nitrogen is removed through the shortened nitrogen removal reaction. The anaerobic ammonium oxidation reactor may utilize a conventional aeration tank or may be additionally installed, but it is advantageous to additionally provide a separate reaction tank suitable for the characteristics of the anaerobic ammonium oxidizing bacteria having a low growth rate. The anaerobic ammonium oxidation reactor can be used in all floatation processes, but the deposition process is advantageous because the deposition process does not require separate solid-liquid separation means and prevents washout of anaerobic ammonium oxidizing microorganisms with a slow growth rate, thereby securing a high concentration of microorganisms I can do it. In the case of the adhered growth process, the filter material is used. Both the supernatant and the submerged filter media can be used, but it is advantageous to use the inversion method for economical and efficient backwashing.

As shown in FIG. 4, when the bioreactor of the existing treatment plant is designed as an organic material removal process, organic substances are removed and the nitrification is accomplished by utilizing the existing reaction tank. If the bioreactor retention time is insufficient, A nitrification tank for nitrifying an etching liquid can be added. The nitrification is accomplished in the nitrite tank, the organic waste is removed from the existing bioreactor, the effluent of the two reactors is introduced into the anaerobic ammonium oxidation tank, and the nitrogen is removed through the shortened nitrogen removal reaction. Some of the primary effluent can be returned to the nitrite tank when the nitrogen in the reflux water can not supply sufficient nitrite. In this case, the amount of sewage introduced into the nitrite tank should not exceed 40% of the total inflow sewage to perform additional nitrification. At this time, it is advantageous to employ an adherent process using an annular-type filter medium in the anaerobic ammonium oxidation tank.

FIG. 5 shows an example in which the concept of FIG. 4 is applied to a conventional treatment plant. All of the existing reaction vessels are removed only by organic substances, and nitrification is performed by installing a separate reaction vessel. At this time, any type of reaction tank can be applied to the nitrite tank, but it is advantageous to use an MBR reactor capable of intensifying by performing solid-liquid separation using a separation membrane.

FIG. 6 is a graph showing the relationship between the concentration of nitrite nitrogen in the nitrification process and the nitrite nitrogen in the nitrification process when the alkalinity in the desolvation solution generated in the sludge treatment process is insufficient for oxidizing ammonia. The nitrite tank can be applied to any type of reaction tank, but it is advantageous to use an MBR reactor capable of nitrification even at a short residence time by performing solid-liquid separation using a separation membrane.

FIG. 7 shows an embodiment in which the concept of FIG. 6 is applied to a conventional treatment plant, in which a part of the recirculated water is introduced into an anaerobic ammonium oxidation tank and nitrite is produced in a nitrite tank using a conventional treatment tank.

Through the present invention, it is possible to change the process economically if the process is changed to a process capable of removing the shortened nitrogen by utilizing the existing treatment plant. Particularly, since the existing first-purifying unit, solid-liquid separating unit and sludge treatment process are used without modification, no additional cost is required. Existing bioreactors are used as organic oxidation reactors and nitrification reactors, and it is not necessary to change any facilities, and it is economical to change the operation method of the process. Since the anaerobic ammonium oxidation reactor can be installed separately, it does not require a separate precipitation process and does not need to be connected to the existing process because it uses an adhered process using an anaerobic ammonium media in consideration of the characteristics of the anaerobic ammonium oxidizing microorganism. Therefore, Can be minimized.

If some residual tank is used, it can be used for CSO treatment.

According to the present invention, since nitrogen is removed through the single-stage nitrogen removal process, it is possible to reduce oxygen by 65% and external carbon source by 100% as compared with the conventional nitrogen removal process.

Claims (6)

A water purification unit having a first purification unit for removing particulate organic matter from the wastewater, a plurality of bioreactors for removing dissolved organic matter of the first settled wastewater, and a solid-liquid separation unit for solid-liquid separation of wastewater from which organic matter has been removed; And
An anaerobic digestion tank for anaerobic digesting the concentrated solids; and a dewatering unit for solid-liquid separating the anaerobically digested solids, wherein the sludge treatment for treating the sludge generated in the water treatment facility Government;
Wherein the waste water treatment apparatus comprises:
The water treatment process unit may further include an anaerobic ammonium oxidation tank at a downstream end of the solid-liquid separation unit,
Wherein a part of the plurality of bioreactors is used as a nitrite reaction tank and is arranged in parallel with the remaining bioreactor, and the nitrite generated in the dehydration part in the nitrite reaction tank is nitrified.
A water treatment facility having a first purification unit for removing particulate organic matter from the wastewater, a bioreactor for removing dissolved organic matter from the first settled wastewater, and a solid-liquid separation unit for solid-liquid separating wastewater from which organic matter has been removed; And
An anaerobic digestion tank for anaerobic digesting the concentrated solids; and a dewatering unit for solid-liquid separating the anaerobically digested solids, wherein the sludge treatment for treating the sludge generated in the water treatment facility Government;
Wherein the waste water treatment apparatus comprises:
The water treatment process unit may further include an anaerobic ammonium oxidation tank at a downstream end of the solid-liquid separation unit,
Wherein the sludge disposal unit further comprises a nitrite tank for nitrifying the desorption liquid at a downstream end of the dehydration unit, so that the desorption liquid generated in the dehydration unit is nitrified and introduced into the anaerobic ammonium oxidation tank.
3. The method according to claim 1 or 2,
Wherein the solid-liquid separator comprises a separation membrane.
3. The method according to claim 1 or 2,
Wherein the anaerobic ammonium oxidation tank employs an attachment process.
3. The method of claim 2,
Wherein a part of the effluent of the primary settling portion flows into the nitrification tank.
5. The method of claim 4,
Characterized in that an adhering type filter material is used in the adhering process.

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