KR101082516B1 - System for treating wastewater - Google Patents

Abstract

PURPOSE: A system for treating sewage and wastewater is provided to overcome the efficiency reduction of nitrogen treatment in winter by reducing a time required for implementing a nitrification. CONSTITUTION: A system for treating sewage and wastewater(100) includes a first processing part(110), a second processing part(120), and a third processing part. The first processing part includes an aerating tank(111), an anoxic tank(1111), and a precipitating tank(112). The second processing part includes a bioreactor using accretion-growth microorganisms. The second processing part transfers nitrate, generated from the second processing part, to the anoxic tank of the first processing part. The third processing part coagulates and filters the effluent from the precipitating tank of the first processing part. A part of overlaying water is introduced from the first processing part to the second processing part, a nitrification is implemented.

Description

Wastewater Treatment System {SYSTEM FOR TREATING WASTEWATER}

The present invention relates to a wastewater treatment system, and more particularly, to a wastewater treatment system easily upgraded an existing wastewater treatment process.

The activated sludge process, which is currently installed in wastewater treatment plants all over the country, is a standard activated sludge process and sequencing batch reactor (SBR) process mainly dealing with organic matter treatment, and MLE (Modified) which mainly treats organic matter, nitrogen and phosphorus. Ludzack-Ettinger process, A2 / O process, Bardenpho process (the above is called nutrient processing process) and various methods are designed, constructed and operated.

Standard activated sludge process is the most used method of sewage treatment. Figure 1 schematically shows the configuration of a standard activated sludge system of a conventional wastewater treatment plant. Referring to FIG. 1, the standard activated sludge system 10 conveys activated sludge corresponding to 20 to 50% of the amount of inflow sewage from the final settler 11 to an aeration tank (active sludge tank) 12 to supply the influent sewage and activated sludge. Mix it. After 4 to 8 hours to give up to discharge the supernatant by separating the sludge from the final settler (11). The standard activated sludge process is the most applied in Korea, and the technology accumulated according to the construction and operation of the treatment facility is sufficient, so that organic materials such as BOD and SS can maintain relatively stable discharge water quality. In addition, maintenance costs are low because no bad products are used, and the activated sludge with good sedimentation is obtained and a normal function can be expected. BOD removal rate is more than 90%, high perspective and low construction cost. However, the abandonment power is relatively high and surplus sludge production is large. In particular, since nitrogen and phosphorus removal efficiency is low, correction and supplementation are required in consideration of strengthened water quality standards. For example, when converting to a biological nutrient treatment process to remove nitrogen and phosphorus, a large site is required to satisfy sufficient hydraulic residence time, and when a coagulation sedimentation plant is added at the rear end, a large amount of chemical sludge is generated and When using filtration) or activated carbon, there is a problem that an increase in site area and maintenance cost is expected.

2 schematically illustrates the configuration of an A2 / O system of a conventional wastewater treatment plant. 2, as a method for removing nitrogen and phosphorus, anaerobic tank (21), anoxic tank (22), aerobic tank (Aerobic Tank) 23, sedimentation basin 24 Equipped. The A2 / O system 20 performs Internal Recycle and Settler Sludge Return to remove nitrate nitrogen. The anaerobic tank 21 releases phosphorus under anaerobic conditions so that the microorganisms can ingest excessively in the aerobic tank 23, and the anaerobic tank 22 denitrates the nitrate nitrogen of the internal transport water of the aerobic tank 23. Do it. It is easy to apply the existing sewage treatment plant to the advanced treatment process, but it requires a lot of hydraulic time to process nutrients nitrogen and phosphorus even in winter, so it requires a lot of site and construction cost. Since phosphorus release is suppressed under anaerobic conditions due to nitrate nitrogen in the return sludge, the phosphorus removal efficiency is low and the BOD / TN ratio is required to be 12 or more, which is inappropriate for the treatment of domestic sewage with low BOD / TN ratio in the influent. Carbon source should be injected. In winter, when the water temperature is lowered, there is a problem that the nitrogen removal efficiency is somewhat reduced.

Furthermore, the Ministry of Environment abolished the total nitrogen and total standards for winter sewage treatment plants over 500㎥ per day from Dec.01.01, and public and private sewage treatment facilities with less than 500㎥ per day from December 15.01. The government stated that it plans to contribute to the improvement of water quality in public waters, and in order to comply with this regulation, existing installed and operated processes alone cannot satisfy the enhanced water quality standards.

In the existing nutrient treatment plant, the nitrification reaction is performed by autotrophs with low growth rate and low activity in winter, and thus the nitrogen treatment efficiency is lowered because nitrification is not performed smoothly. In order to solve the problem in the winter season, a rapid nitriding reaction should be performed. To this end, it is necessary to suppress the growth and growth of taga trophic microorganisms, which is a competitor of nitrification and enrichment and nitrification microorganisms. The densification and concentration of the former nitrifying bacteria can be solved by adhesion growth of nitrifying microorganisms, and the latter can reduce the growth of taga trophic microorganisms during nitrification by first treating organic matters before nitrifying reaction.

In general, there is no degradation of nitrification in summer, but severe degradation of nitrification occurs in winter. In winter, if only nitrification is completed in a short time, subsequent denitrification is not a problem. Therefore, in order to improve the efficiency of the nutrient treatment in winter, a process to improve the nitrification process from the existing treatment should be developed.

In general, the biofiltration system using biofiltration fills the biofiltration to the biofiltration system at an appropriate ratio, attaches microorganisms to the biofiltration, and treats organic matter and nutrients by biological mechanisms, or inflow and outflow of wastewater. Some of the solids are treated by filtration. Wastewater treatment technology using biofiltration can increase the amount of microorganisms in the reactor by inducing the growth of microorganisms, which allows the treatment of high load wastewater in a short time, and its toxicity even when inflow of toxic substances from the outside Less influenced by the material, and also in the low temperature of winter in Korea, the temperature is less affected by the temperature and can be appropriately treated. However, in spite of these advantages, the method of simply filling the biofiltration system with the biofiltration cannot bring about the maximization of the treatment efficiency using the filtration and the biological treatment mechanism due to the fundamental problem of the conventional biofiltration. When the wastewater flows into the upstream type, which is widely used in the existing biofiltration system processes, most of the solid material accumulates in the lower part of the biofiltration system and not only blocks the media but also reduces the filtration efficiency by shortening the filtration time. As a result, the underlying problems of existing biofiltration have resulted in deterioration of biological and physical sewage treatment efficiency of biofiltration systems. Therefore, in order to grow and concentrate nitrifying microorganisms, material transfer should be smooth and blockage should not occur. To this end, the concentration of solids in the device or in the incoming wastewater to solve the obstruction should be significantly low.

It is an object of the present invention to provide a wastewater treatment system capable of satisfying effluent water quality standards that are strengthened regardless of seasonal changes by upgrading existing wastewater treatment processes.

Another object of the present invention is to provide a wastewater treatment system that can further install a bioreactor at the end of the existing treatment process to promote the nitrification reaction, thereby improving the treatment efficiency of nutrients.

It is still another object of the present invention to provide a wastewater treatment system in which an existing treatment plant has been upgraded to satisfy enhanced effluent water quality standards.

The present invention includes the problems of supplementing existing plant facilities to meet the above-mentioned strengthened water quality standards, and in particular, the upgrade of existing plant using adherent growth microorganisms to improve winter nitrogen removal efficiency.

The present invention does not simply combine adherent growth microorganisms such as a conventional bioreaction process and a biofiltration process, but constitutes an optimal system by supplementing the disadvantages of the two processes. The biggest problem of the existing biological reactor is the decrease in nitrification efficiency due to the decrease in winter temperature, and thus the decrease in total nitrogen treatment efficiency. Among the nutrients that must meet the tightening standards, in particular, treatment of phosphorus is limited by biological treatment alone.

In order to solve the above problems, in the present invention, in the case of the existing standard activated sludge, it is intended to introduce a method in which a part of the bioreactor is replaced with an anaerobic tank and nitrified ammonia nitrogen in the effluent in an external nitrification tank. That is, in order to improve the nitrification and denitrification efficiency, a separate nitrifier is introduced through the concentrated aerobic tank before the part of the effluent is recycled to the anoxic tank. The aerobic tank is filled with bile and medium to grow adherent growth nitrifying microorganisms. Adhesion and growth reaction using the media and media include processes using flotation media and processes using rotating discs. In case of using a rotating disc type aerobic reaction tank, because the disc rotates, the biofilm is naturally detached from the surface of the disc by the rotating friction, so no backwashing process is required. It has the advantage of eliminating the possibility of blocking the fluid behavior by filling the solid material. In order to minimize energy consumption in the rotating disk reactor, a high buoyancy material may be inserted between the disks to minimize the underwater weight of the rotating disk device. This is a technology with high utilization value because it can be easily applied even with a simple change of an existing treatment plant.

On the other hand, in the case of applying the flotation media for the adhesion growth reaction, the general filtration process is affected by the inflow SS amount, resulting in the backwashing problem and the efficiency degradation due to microbial detachment phenomenon. However, since the present invention treats a part of the effluent treated through a biological process separately from the existing biofiltration problem through recycling, various problems that may occur during treatment such as occlusion may be minimized. It can be overcome enough. In other words, the backwash cycle can be lengthened, the problem of underfloor accumulation of suspended solids can be overcome, and unnecessary microbial desorption due to frequent backwash can be prevented. By applying this technology to an existing treatment plant, it aims to develop a process that can maximize the treatment efficiency by applying a packaged biofiltration mixing process without a large-scale expansion.

However, the problem of the process is that the flow load of the settling tank is increased to shorten the hydraulic retention time of the settling tank has a problem that can reduce the load of the settling basin. In this case, it is necessary to install a slope plate in the sedimentation basin. In particular, the inclined plate installed in the sedimentation tank is connected to the floating body with an elastic connecting line to float in the sedimentation tank, thereby maximizing the treatment of the inclined plate and treating the sediment and increasing the surface area of the final sedimentation basin to increase the flow rate of water and sewage. It is possible to prevent economic deterioration due to sludge spillage due to change, and economical effect can be expected as there is no need to remodel sedimentation tank facilities in water and sewage treatment plants.

According to one aspect of the present invention to achieve the above object,

A first treatment unit treating organic matter, nitrogen and phosphorus using a standard activated sludge, A / O, A2 / O, SBR, Bardenpho, MLE or an intermittent aeration treatment method and having an oxygen-free reaction zone; And a second processing unit connected to a rear end of the first processing unit and having an aerobic reaction tank using a medium, wherein a portion of the supernatant of the first processing unit is introduced into the second processing unit to perform nitrification, and the second processing unit is performed. The nitrate produced in the step is returned to the anoxic reaction zone of the first treatment unit is provided by the waste water treatment system, characterized in that the denitrification using the organic matter contained in the influent water of the first treatment unit.

The first treatment unit may be an apparatus using an activated sludge method having an aerobic tank, and the anoxic reaction region may be formed by modifying the aerobic tank of the first treatment unit.

The first processing unit is a device using a nutrient processing method having an anoxic tank, and the nitrate generated in the second processing unit may be returned to the anoxic tank of the first processing unit.

The second processing unit may include at least one expiratory tank, and the second processing unit may be two or more exhalation tanks connected in multiple stages.

The second treatment unit may include a bioreactor using the aerobic growth microorganism.

In the first treatment unit, the settling tank may be provided with an attached or fixed inclined plate to reduce the load.

The wastewater treatment system may further include a third treatment unit for coagulating filtration of the effluent bath of the first treatment unit.

According to the present invention, the object of the present invention described above can be achieved. Specifically, the wastewater treatment system upgraded to the existing treatment plant according to the present invention can satisfy the water quality standards that are strengthened by a simple additional device as an optimal process for further removing the existing untreated nitrogen and phosphorus.

Existing nutrient treatment plant is a nitrogen nitrate reaction is not smooth due to the low efficiency of the winter treatment efficiency, which leads to a decrease in nitrogen treatment efficiency, thereby reducing the phosphorus treatment efficiency. In order to solve the problem in the winter season, a rapid nitriding reaction should be performed. To this end, it is necessary to suppress the growth and growth of taga trophic microorganisms, which is a competitor of nitrification and enrichment and nitrification microorganisms. The former can be solved by adhesion growth of nitrifying microorganisms, and the latter can reduce the growth of other nutrients during nitrification by first treating organic matters before nitrification.

In general, there is no deterioration of nitrification in summer, but deterioration of nitrification occurs in winter. Even in winter, if only nitrification is completed in a short time, subsequent denitrification may not be a problem. Therefore, if the technology of the present invention is applied to an existing treatment plant, it is possible to sufficiently solve the winter nutrient treatment problem.

1 is a schematic view showing a standard activated sludge system of an existing wastewater treatment plant.
2 is a schematic view showing an A2 / O system of an existing wastewater treatment plant.
3 is a schematic view showing a wastewater treatment system according to a first embodiment of the present invention, which is an upgrade of a standard activated sludge system of an existing wastewater treatment plant.
Figure 4 is a schematic view showing a wastewater treatment system according to a second embodiment of the present invention, an upgrade of the standard activated sludge system of the existing wastewater treatment plant.
5 is a configuration diagram schematically showing a wastewater treatment system according to a third embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic view showing a wastewater treatment system according to a first embodiment of the present invention, which is an upgrade of a standard activated sludge system of an existing wastewater treatment plant. The wastewater treatment system 100 includes a first treatment unit 110 and a second treatment unit 120. In the present invention, the first treatment unit 110 refers to an A / O process that is installed in an existing wastewater treatment plant and is operated to treat nitrogen and phosphorus, and the second treatment unit 120 is a separate to increase nitrification efficiency. It means the process added by connecting the aerobic tank.

The first treatment unit 110 is an improvement of the existing standard activated sludge system to the A / O type process. The first processing unit 110 includes a reaction tank 111 and a precipitation tank 112 that are sequentially positioned from the front end. The reactor 111 is a part of an aerobic tank installed and operated in an existing wastewater treatment plant, and adds an anaerobic region. The reactor 111 includes an anoxic reaction unit 1111 and an aerobic reaction unit 1112 and, if necessary, an aerobic reaction unit 1112. Internal circulation in the anaerobic reaction unit 1111. The oxygen-free reaction unit 1111 is configured to mix the activated sludge by stirring without inflow of oxygen. In this embodiment, the reactor 111 can be configured by modifying the aerobic tank of the existing standard activated sludge system. The settling tank 112 may be provided with an attached or fixed inclined plate to reduce the load of the settling tank.

The second processing unit 120 includes an aerobic tank 121 using a medium. The second processing unit 120 may be formed by connecting two or more aerobic tanks in multiple stages. In addition, the aerobic tank 121 of the second processing unit 120 may be a bioreactor using adhesion-grown microorganisms, such as a rotating disk-type reactor and a biofiltration reactor.

Referring to the operation of the first embodiment shown in Figure 3 as follows. The external inflow water into the anoxic reaction unit 1111 and the nitrate generated by the nitrification reaction in the second processing unit 120 are introduced into the anoxic reaction unit 1111. The nitrate returned to the anoxic reaction unit 1111 uses organic matter contained in the external influent for denitrification, and phosphorus is released. Next, in the aerobic reaction unit 1112, mechanisms such as organic matter oxidation, nitrification, and phosphorus absorption occur. In some cases, a part of the sludge is conveyed internally from the aerobic reaction unit 1112 to the anoxic reaction unit 1111 to increase the efficiency of nitrogen and phosphorus removal. After the reaction is completed, the sludge is passed to the settling tank 112, the sludge precipitated in the settling tank 112 is concentrated and returned to the anoxic reaction unit 1111, and some of the sludge is disposed of as a waste sludge, the supernatant is the second treatment unit 120 To some inflow, and the rest to outflow. Part of the supernatant flowing out of the first processing unit 110 flows into the inflow water flowing into the second processing unit 120, and the other outflow water is discharged as it is. The reaction in the aerobic tank 121 of the second processing unit 120 is an untreated organic matter and nitrification reaction by the aerobic reaction, and using a growth-grown microorganism as a reaction using a medium through the concentration and denaturation of nitrifying microorganisms Even in winter, high nitrification efficiency can be expected in a short time. In addition, in order to improve phosphorus removal efficiency, a biofiltration reactor may be installed at the rear end of the discharged effluent and a flocculant may be introduced at the front of the biofiltration reactor to improve the phosphorus removal efficiency.

Figure 4 is a schematic view showing a wastewater treatment system according to a second embodiment of the present invention, an upgrade of the standard activated sludge system of the existing wastewater treatment plant. The wastewater treatment system 200 includes a first treatment unit 210 and a second treatment unit 120. Since the configuration of the second processing unit 120 is the same as that of the second processing unit 120 illustrated in FIG. 3, a detailed description thereof will be omitted.

The first treatment unit 210 is an improvement of the existing standard activated sludge system to an A2 / O type process. The first processing unit 210 includes an anaerobic tank 211, an anaerobic tank 212, an aerobic tank 213, and a settling tank 214 that are sequentially positioned from the front end. The aeration tank 213 and the settling tank 214 are configurations used in existing standard activated sludge systems. That is, the first processing unit 210 is converted to an A2 / O type process by adding an anaerobic tank 211 and an anaerobic tank 212 to the existing standard activated sludge system. The anaerobic tank 211 releases phosphorus under anaerobic conditions so that the microorganisms can ingest light in the aerobic tank. The action of the oxygen-free tank 212 is largely the same as the oxygen-free reaction unit 1111 in the embodiment shown in FIG.

Referring to the operation of the second embodiment shown in Figure 4 as follows. The external inflow water to the anaerobic tank 211 and, if necessary, a portion of the nitrate produced by the nitrification reaction is returned to the second processing unit 120. The nitrates returned to the anaerobic tank 211 are denitrified by the organic matter contained in the external influent and release of phosphorus. In the oxygen-free tank 212, the denitrification reaction and the phosphorus release reaction of the nitrate passed from the second treatment unit 120 occur. Next, in the aerobic tank 213, mechanisms such as organic material oxidation, nitrification, and phosphorus absorption occur. In some cases, a part of the sludge is conveyed internally from the aerobic tank 213 to the anoxic tank 212 to increase the nitrogen removal efficiency. After this reaction, the sludge is passed to the settling tank 214, and the sludge precipitated in the settling tank 214 is concentrated and returned to the anaerobic tank 211, a part is disposed of as waste sludge, and the supernatant water is transferred to the second treatment unit 120. Some are inflow, others are outflow. Part of the supernatant flowing out of the first processing unit 210 flows into the inflow water flowing into the second processing unit 120, and the other outflow water is discharged as it is. The reaction in the aerobic tank 121 of the second processing unit 120 is an aerobic reaction, in which untreated organic matter and nitrification reaction are performed, and concentration and denaturation of nitrifying microorganisms as a step using adhesion-growing microorganisms as a reaction using bile and medium. Through this, even in winter, high nitrification efficiency can be expected in a short time. In addition, in order to improve the efficiency of phosphorus removal, a biofiltration reactor may be installed at the rear end of the effluent and a coagulant may be administered at the front of the biofiltration reactor to improve the phosphorus removal efficiency.

5 schematically shows a wastewater treatment system according to a third embodiment of the present invention, which is an upgrade of an existing biological nitrogen and phosphorus (nutrient salt) treatment wastewater system. The wastewater treatment system 300 includes a first treatment unit 310, a second treatment unit 120, and a third treatment unit 330. The first processing unit 310 is a manufacturing process (A / O, A2 / O, SBR, Bardenhop, MLE, intermittent aeration treatment tank, etc.) used as an existing nutrient treatment process. The second processing unit 120 is the same as the second processing unit of the first embodiment and the second embodiment. The third treatment unit 330 adds a coagulation filtration process to the effluent of the first treatment unit 310 for phosphorus treatment. In the process used for the existing nutrient treatment process, even if the hydraulic residence time is short and the nitrification efficiency is low due to the winter temperature drop, the second treatment unit 120 is added to improve the nitrification and then the denitrification reactor of the existing nutrient treatment process. It can be introduced into the nitrogen to improve the efficiency of nitrogen treatment. The third processor 330 is installed for further phosphorus treatment.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. The above embodiments may be modified or changed without departing from the spirit and scope of the present invention, and those skilled in the art will recognize that such modifications and changes also belong to the present invention.

100: wastewater treatment system 110: first treatment unit
120: second processing unit 330: third processing unit

Claims (8)

An aerobic tank using organic sludge process with an anoxic reaction zone, treating organic matter, nitrogen and phosphorus using standard activated sludge, A / O, A2 / O, SBR, Bardenpho, MLE or intermittent aeration treatment A first treatment unit including an anoxic reaction zone formed by an anaerobic reaction unit and an aerobic reaction unit by remodeling the aerobic tank, an anoxic tank using a double salt treatment method, and a settling tank on which an attached or fixed inclined plate is installed to reduce load;
An aerobic tank using a medium connected to the rear end of the first processing unit, and having a bioreactor using adhesion-grown microorganisms, and connected to one or two or more stages, and the resulting nitrate is returned to the anaerobic tank of the first processing unit 2 processing section; And
A third treatment unit selectively added to coagulate and filter the sedimentation tank effluent of the first treatment unit;
And a portion of the supernatant water of the first treatment part is introduced into the second treatment part to perform nitrification, and the nitrate generated in the second treatment part is returned to the anoxic reaction region of the first treatment part and Waste water treatment system characterized in that the denitrification using the organic matter contained in the influent.

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