KR100836231B1 - Process of small-scale wastewater treatment using biosorption mechanism - Google Patents

Abstract

A process of small-scale wastewater treatment using biosorption mechanism is provided to treat effectively organic matters and nutrients contained in wastewater having a low carbon/nitrogen(C/N) ratio by installing an aerobic reactor with a size which is 1.5 to 2.0 times larger than that of an anoxic reactor, thereby securing a sufficient time for nitrification. A process of small-scale wastewater treatment using biosorption mechanism comprises: changing an inflow channel between an A mode in which wastewater is sequentially flown into a first anoxic reactor(1) for adsorbing organic matters contained in wastewater by microorganisms, and an aerobic reactor(2) and a second anoxic reactor(3) for performing a nitrification process by concentrated nitrifying bacteria on ammonia nitrogen in the wastewater passing through the organic adsorption process and a B mode in which wastewater is sequentially flown into the second anoxic reactor(3) for adsorbing organic matters contained in wastewater by microorganisms, and the aerobic reactor(2) and the first anoxic reactor(1) for performing a nitrification process by concentrated nitrifying bacteria on ammonia nitrogen in the wastewater passing through the organic adsorption process; bypassing a portion of the wastewater flown into the aerobic reactor to the first anoxic reactor and the second anoxic reactor; and continuously bypassing a portion of the wastewater flown from the aerobic reactor into the first anoxic reactor, or from the aerobic reactor into the second anoxic reactor to the aerobic reactor by an internal circulation pump, wherein the A and B modes are changed at time intervals of 30 to 60 minutes by an inflow pump, size of the aerobic reactor is 1.5 to 2.0 times larger than that of the second anoxic reactor to secure sufficient time for the nitrification, and the portion of wastewater is internally circulated at a ratio of 1 to 4Q from the aerobic reactor into the second anoxic reactor in case of the A mode and from the aerobic reactor into the first anoxic reactor in case of the B mode so as to improve denitrification efficiency.

Description

Small-scale Wastewater Treatment Method Using Biosorption Mechanism {PROCESS OF SMALL-SCALE WASTEWATER TREATMENT USING BIOSORPTION MECHANISM}

1 is a process chart showing a small-scale wastewater treatment method using a biosorption mechanism according to a first embodiment of the present invention.

2 is a process chart showing a small-scale wastewater treatment method using a biosorption mechanism according to a second embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1: first anoxic reactor

2: aerobic reaction tank

3: second anoxic reactor

4: floating media

The present invention relates to a small-scale wastewater treatment method using a bioadsorption mechanism, and more particularly, A mode in which the wastewater is sequentially introduced into the first anoxic reaction tank, the aerobic reaction tank, and the second anoxic reaction tank at a predetermined time interval. ), The second anoxic reaction tank, the aerobic reaction tank, and the first anoxic reaction tank, the inflow passage is changed to B mode where the wastewater is sequentially introduced and treated, and some of the wastewater flowing into the aerobic reaction tank is the first anoxic reaction tank. A part of the wastewater flowing into the second anoxic reactor or from the aerobic reactor to the first anoxic reactor or from the aerobic reactor to the second anoxic reactor is continuously bypassed by an internal circulation pump to the aerobic reactor. Small scale wastewater treatment method using adsorption mechanism.

In general, the nutrients contained in the waste water are inorganic elements, but they flow into rivers, coastal seas, lakes (lakes and reservoirs), etc. to promote algae growth and cause eutrophication.

In addition, when the nutrients contained in the wastewater enter the coastal seas, they cause red tide. If the nutrients are badly decayed and odors are generated in the bottom, it acts as a cause of water pollution. The substance to be removed before entering the appeal.

In Korea, most sewage and wastewater treatment relies on activated sludge. Most suspended solids and organics can be removed by treatment with activated sludge, but only 20-40% of nutrients such as nitrogen and phosphorus are treated.

Methods for treating nutrients such as nitrogen and phosphorus include physical and chemical treatment methods and biological treatment methods. Physical treatment methods include ammonia degassing, ion exchange, and struvite formation and precipitation. The method is disadvantageous in that it is temperature sensitive and expensive, and there is a tendency to be reluctant to use in the field due to unstable water as well as operational difficulties.

On the other hand, in the biological treatment methods, and the nitrification (transformation of ammonia into nitrate form) by nitrifying bacteria (such as ie., Nitrosomonas & Nitrobacter) the ammonia nitrogen and organic nitrogen in the case of nitrogen dissolved state in an aerobic condition, nitrate The denitrification bacteria (ie, Pseudomonas, Paracoccus denitrifiers, etc.) are used as electron acceptors instead of oxygen under anoxic conditions, converted to nitrogen gas, and released into the atmosphere (denitrification). In the case of phosphorus, wastewater is alternately maintained under anaerobic and aerobic conditions, and in anaerobic conditions, phosphorus-removing microorganisms (ie, Acinetobacter And the like, and in subsequent aerobic conditions, the microorganisms overdose the phosphorus and then remove the phosphorus in the wastewater by removing the microorganisms by a certain amount. The degree of ingestion of microorganisms in aerobic conditions depends on the amount and type of organic matter introduced into anaerobic conditions, especially in the case of maintaining a pure anaerobic condition and when the organic matter contains a large amount of organic acid salts such as acetate. The amount of release is enhanced and the intake of phosphorus in the subsequent exhaled state is improved, thereby increasing the throughput.

Therefore, biological nitrogen and phosphorus removal method is appropriately arranged anaerobic-aerobic-anaerobic-aerobic reactors in accordance with the characteristics of each reactor to induce organic oxidation and nitrification reaction and microorganism intake of phosphorus in the aerobic reactor, and in anaerobic and anoxic reactor Nitrate nitrogen is converted to nitrogen gas to induce denitrification and phosphorus release into the atmosphere.

The biological denitrification process was first developed in 1960 by the Wuhrmann process, a post-denitrification process proposed by Wuhrmann. The post-denitrification process injected electron donors from the outside, so the treatment efficiency was high. However, as the cost of the injected external electron donors (Methanol, etc.) increases, the anoxic bath is placed in front of the oxygen bath, so that organic matter in the wastewater can be used for denitrification. The Ludzack-Ettinger process, a total denitrification process, was developed. The total denitrification process using organic matter in the wastewater instead of methanol is oxidized in the ammonia aerobic reaction tank and sent to the anoxic tank via the return sludge. The return sludge alone had very low nitrogen removal efficiency. Barnard improved the total nitrogen removal rate by 88% by returning the aeration tank mixture of 2-4Q from the aerobic reactor to anoxic tank to compensate for the shortcomings of this process.Then, based on the concept of Modified Ludzack-Ettinger process, Modified Bardenpho , UCT and VIP processes have been developed and put into practical use. The representative examples of the side streams are the Phostrip Process and the PL-II Process developed in Korea. The Phostrip Process was developed by Levin as a process that combines chemical methods with biological removal. Existing Phostrip process is stable in phosphorus removal, but considering the nitrogen removal, there is a problem that the construction cost by the nitrification and denitrification facility installation takes a lot. In the FPL-IIProcess, phosphorus emission between the secondary settling basin and the dephosphorization tank of the existing Phostrip process is not significantly affected, and also the nitrogen removal of the entire system is achieved by increasing the return rate to the dephosphorization tank. Bio-denipho process that changes the direction of flow between reactors and converts the reaction tank to aerobic / anaerobic cycle by controlling wastewater inflow and oxygen injection periodically, and Bio-denipho process that improves phosphorus removal by placing anaerobic reactor at the front end (aka Kruger) system has been developed and put into practice in Europe. This technology, which combines the flow changing technology with intermittent aeration, was developed in Denmark. It is called PID (Phased Isolation Ditch) process and operates in a dynamic state, which can save energy significantly compared to activated sludge. It is evaluated as a technique.

Although the above-mentioned processes have been put to practical use in developed countries and used for sewage treatment for organic and nutrient salt treatment, these processes are designed around nitrided bacteria with relatively low growth, and the hydraulic residence time is about 15-24 hours. In developed countries, there is no case where the nutrient treatment plant is installed without additional expansion in the treatment plant with a hydraulic residence time of less than 6 hours.

The treatment method using the adsorption of organic matter by extracellular polymer of microorganisms has been developed as a contact stable activated sludge process and has been used for the past 40 years. The Dephanox process developed in Italy in the 1990s also uses biosorption mechanisms, but it affects the adsorption. In the Dephanox process, the inflow organic matter is precipitated after contact stability of the sludge, and it is transferred to the denitrification tank and used as organic material for denitrification. There is a disadvantage in that the total nitrogen concentration of the treated water is high because it is not removed. Therefore, although it is an excellent method of maximizing the use of the influent organic matter without input of external carbon source when removing nitrogen, it is not widely used at present.

In Korea, more than 20 nutrient treatment methods have been developed for the treatment of nutrients in sewage and are under construction to be applied on a site scale. However, most of these processes rely on simple imitation and modification of foreign technology. There are many problems in using them when the residence time is short and the temperature is low in winter. Especially, sewage with low C / N ratio (inflow water quality of organic matter and nitrogen), like Korea's sewage, is gradually used in the future. There are a number of problems when considering the tightening water quality standards. Developed by Hanwha R & D Center in collaboration with the university, the new technology and patented Euro-change intermittent aeration process (aka HDF) can be easily applied to existing treatment plants by adjusting piping and aeration devices. The low C / N ratio of domestic sewage is not solved. In case of low C / N ratio, such as domestic sewage, research on using acetate as an external carbon source to be supplied for nutrient treatment was developed by Samsung Engineering, and a technology was developed using organic oxidation of wastewater in the wastewater. Although it was reflected in the construction of the treatment plant, there was a problem that could not solve the separate cost problem due to the external carbon source injection.

In other words, the existing biological treatment method is due to the reduction of TN removal efficiency due to the low C / N ratio of the influent, the lack of electron donor in the denitrification reaction due to the decomposition of organic matter in the nitrification reaction, the decrease in treatment efficiency at low COD inflow, and the long hydraulic residence time. There was a problem that large amounts of wastewater could not be treated.

In order to solve the above problems, in the present invention, two anoxic reaction tanks capable of adsorption and denitrification of organic substances by microorganisms such as bacteria and one aerobic reaction tank performing nitrification reactions, each of which has a floating filter (eg; EPs filter) is used to change the inflow channel at regular intervals or to operate the internal circulation according to the situation.The size of aerobic reactor is 1.5 ~ 2.0 times that of anoxic reactor to secure sufficient time for nitrification. It provides an effective treatment method for treating organic matter and nutrients in wastewater having low C / N ratio (influent water organic matter and nitrogen ratio), and complements the shortcomings of the existing biological treatment methods. In addition, the bioadsorption mechanism, a treatment method that is considered in terms of installation and operation, To provide a scale wastewater treatment method for that purpose.

In order to achieve the above object, the present invention provides a first anoxic reaction tank (1) for adsorbing organic matter contained in wastewater by microorganisms at predetermined time intervals, and concentrates ammonia nitrogen in wastewater that has undergone organic matter adsorption. A mode in which wastewater is sequentially introduced and treated into an aerobic reaction tank (2) and a second anoxic reaction tank (3) which undergo nitrification by nitrifying bacteria,

A second anoxic reaction tank (3) for adsorption treatment of organic matter contained in the wastewater by microorganisms (3), an aerobic reaction tank (2) for nitrification of ammonia nitrogen in the wastewater that has undergone organic matter adsorption through concentrated nitrification bacteria, and first anoxic acid The inflow passage is changed to B mode in which wastewater is sequentially introduced into the reactor 1 and treated.

Some of the wastewater flowing into the aerobic reaction tank (2) is bypassed to the first anoxic reaction tank (1), the second anoxic reaction tank (3),

Part of the wastewater flowing from the aerobic reaction tank (2) to the first anoxic reaction tank (1) or from the aerobic reaction tank (2) to the second anoxic reaction tank (2) is continuously fed to the aerobic reaction tank (2) by an internal circulation pump. Small-scale wastewater treatment method using a biological adsorption mechanism, characterized in that bypassed to the main configuration.

The mode A and the mode B are in order to improve the denitrification efficiency, in the case of the A mode, from the aerobic reaction tank to the second anoxic reaction tank, and in the case of the B mode, the first mode in the aerobic reaction tank. It is characterized in that the internal circulation in the rate of 1-4 times (1-4Q) of the inflow water into the anoxic reaction tank.

The first anoxic reaction tank, the aerobic tank, and the second anoxic reaction tank are characterized in that the flotation filter is filled.

Small-scale wastewater treatment method using the biosorption mechanism of the present invention for the removal of organic matter and nutrients (especially nitrogen and phosphorus) contained in low C / N ratio wastewater, especially village sewage and small sewage and wastewater difficult to treat As a method, three towers filled with flotation media can be efficiently treated to treat contained organic matter, nitrogen, and phosphorus without injecting a separate external carbon source [patent 0670211; "Bio Flotation process using biosorption mechanism ”].

Major features of small-scale wastewater treatment using biosorption mechanism, which is a purification method that can effectively remove nitrogen from wastewater, which is the main cause of pollution and eutrophication of lakes or streams, as well as wastewater with low C / N ratio like urban sewage in Korea It is designed to effectively remove nitrogen using only organic matter in waste water without separately injecting organic matter necessary for waste water treatment from the outside.

The reactor consists of three filling towers filled with floating media. The waste water flow can be fluidly operated depending on the operating conditions, and is discharged after passing through an anaerobic reactor → aerobic reactor → anoxic reactor. By changing the flow path, the influent flow is effectively controlled by using two anoxic reactors and one aerobic reactor to increase the efficiency of treating nutrients in sewage with low C / N ratio, increasing nitrification rate, and hydraulic retention time of the whole process. Shortening, protecting nitrids from toxics as toxics are adsorbed and removed together, preventing them from affecting nitrification reactions. Organic adsorption, denitrification and nitrification are carried out by adherent microorganisms attached to the media. Compared to the reduction of the influence of temperature, usable at a small site area and low concentration of particulate organic matter in the influent sewage, the filter medium has a kind of filtration action to improve the organic treatment efficiency compared to the existing biological treatment method. In particular, differentiation from Patent No. 0670211 can reduce the installation cost and operating cost by minimizing unnecessary equipment by reducing the reaction tank from four to three.

Hereinafter, the technical configuration will be described in more detail with reference to the accompanying drawings. First, briefly with reference to the drawings, Figure 1 shows a rubbing nutrient treatment method using a flotation filter according to a first preferred embodiment of the present invention, Figure 2 shows a wound filter according to a second preferred embodiment of the present invention It shows the rubbing nutrient treatment method used.

As shown in FIG. 1, the wastewater introduced into the A mode is introduced into the aerobic reactor 2 through the first anoxic reactor 1, where the flow path is changed and the previously introduced wastewater is the first stage of the B mode. 2 to the oxygen-free reaction tank (3).

First, wastewater flows into the first anoxic reactor (1) and the second anoxic reactor (3),

In the first anoxic reaction tank (1) and the second anoxic reaction tank (3), the supernatant with concentrated ammonia nitrogen flows into the aerobic reaction tank (2) through organic matter adsorption process,

The supernatant introduced into the aerobic reaction tank (2) is subjected to nitrification by the flotation media (4) in which the nitrifying bacteria in the aerobic reaction tank (2) are concentrated, and the nitrification is introduced through mode A of the supernatant completed. The supernatant is introduced into the second anoxic reactor 3, and the supernatant introduced through the B mode is discharged through the step of entering the first anoxic reactor 1.

Each of the reaction tanks (1, 2, 3) is filled with a floating filter (4), the floating filter (4) plays a role in which the biological function by the microorganisms attached to the filter medium and the filtration function which is the physical action of the filter medium occurs simultaneously. As the type of media, the cell structure is formed in an independent structure (closed type), and EPs, etc., which are excellent in flexibility due to the influence of PP resin, are preferable, and the shape is composed of a spherical shape, a rod shape, and a donut shape.

Looking at the above-described technical configuration in more detail by process as follows.

1st process

As shown in FIG. 1, the apparatus for performing the wastewater purification method according to the first process includes a first anoxic reactor (1), an aerobic reactor (2), and a second anoxic reactor (3). Filled with floating media (4).

The treatment flow of the wastewater according to the first step is introduced into the first anoxic reaction tank (1) in the A mode by the inflow pump for a predetermined time, and then sequentially in the aerobic reaction tank (2) and the second anoxic reaction tank (3). After a certain period of time (30 to 60 minutes), the flow path of the influent wastewater is changed from mode A to mode B by the inflow pump so that the second anoxic reactor (3) and the aerobic reactor (2) The first anaerobic reaction tank (1) is sequentially passed.

In the case of the mode A, the first anoxic reactor 1 serves to adsorb organic matter introduced into the wastewater by the microorganisms attached to the flotation media 4 in the reaction tank, and the adsorbed organic material is the B mode (mode In the aerobic reaction tank (2) through the nitrification by the adhesion growth concentrated nitrification, the resulting nitrate is used to enter and denitrify to maximize the use of organic matter.

After the biosorption, the supernatant with concentrated ammonia nitrogen exits the strainer and enters the aerobic reactor (2). Part of the supernatant introduced into the aerobic reaction tank (2) can be continuously circulated to the first anoxic reaction tank (1) according to the situation, and the supernatant introduced through the B mode (mode) can be circulated in the first anoxic reaction tank (1). After the denitrification is completed, the outflow is performed, and a part of the supernatant flowing out may continuously circulate the first anoxic reactor 1.

The aerobic reaction tank (2) is ammonia nitrogen is obtained through the organic material adsorption process in the first in the first anoxic reaction tank (1) and the second anoxic reactor (3) influent sewage flowing through the mode A and mode (B) The concentrated supernatant is introduced and the introduced ammonia nitrogen is subjected to nitrification by the concentrated nitride bacteria concentrated in the flotation media (4) filled in the aerobic reaction tank (2).

The supernatant after nitrification exits the strainer and the supernatant introduced through mode A is the second anoxic reactor 3, and the supernatant introduced through mode B is introduced into the first anoxic reactor 1. In this process, part of the supernatant introduced into the second anoxic reaction tank 3 and the first anoxic reaction tank 1 is continuously circulated through the aerobic reaction tank 2 according to the situation.

The second anoxic reaction tank (3) serves to adsorb the organic material introduced in the wastewater introduced through the B mode (microorganism) attached to the growth medium (4) in the reaction tank, the adsorbed organic material is A mode (mode) is used to enter the aerobic reaction tank (2) to denitrify the nitrate produced after nitrification by the adherent growth concentrated nitride bacteria to maximize the use of organic matter. After the biosorption of organic matter from the wastewater introduced in mode B, the supernatant flowing into the aerobic reactor 2 and the denitrified supernatant flowing into mode A exit the strainer, and some of the supernatant is discharged. In order to improve efficiency, the first anoxic reactor 1 is continuously circulated according to the situation.

2nd process

The second process is a process designed to improve the denitrification efficiency of the first process.

As shown in FIG. 2, when the nitrate nitrated by the nitrifying microorganisms adhering to the flotation media 4 of the aerobic reaction tank 2 is in the A mode, the amount of inflow of water into the second anoxic reaction tank 3 is increased. 1-4 times (1-4Q) to circulate internally, in case of B mode (mode), the first oxygen-free reaction tank (1) to internally circulate 1-4 times (1-4Q) of the inflow of denitrification efficiency Maximizes. The second step differs from the first step in that there is an internal circulation from the aerobic reaction tank (2) to the second anoxic reaction tank (3) and the first anoxic reaction tank (1). Same as 1 step.

In the first step and the second step of the present invention, the first anoxic reaction tank (1), the aerobic reaction tank (2), and the secondary filter (4) filled in the second anoxic reaction tank (3) undergo a backwashing process once a day. Solids separated by backwash are discharged through the drain holes under each reactor.

As described above, the small-scale wastewater treatment method using the biosorption mechanism according to the present invention can maximize the nitrogen treatment, which is the main cause of eutrophication, compared to the existing biological treatment method.

Next, the method of utilizing the bioabsorption using the floating media of the present invention to the maximum has greatly improved the disadvantages of the method using the existing floating microorganisms and floating media. In other words, by changing the flow path at regular intervals, the aerobic tank nitrifies the supernatant water in which the organic matter is adsorbed in the first anoxic reactor and the second anoxic reactor, and thus nitrification is possible in a short hydraulic retention time. In accordance with the first anoxic reaction tank and the third anoxic reaction tank by efficiently performing the denitrification function using the organic material adsorbed to the flotation filter, it is possible to maximize the denitrification efficiency of the sewage having a low C / N ratio.

 Next, when wastewater containing toxic substances such as heavy metals is introduced into the process, the supernatant with concentrated ammonia nitrogen is adsorbed after adsorbing the toxic substances in the first anoxic reactor and the second anoxic reactor according to the flow path direction. Since nitrification is carried out in the bath, it has the advantage of protecting the nitrifying bacteria, which are relatively vulnerable to toxic substances, and has the advantage of being less affected by temperature than the floating growth. In addition, since each reactor is filled with flotation media, almost no sludge is generated, and since there is no need for a sedimentation basin, the area can be reduced and a similar efficiency can be achieved even if the number of reactors is reduced.

Claims (3)

First anoxic reaction tank (1) for adsorption treatment of organic matter contained in wastewater by microorganisms (1), aerobic reaction tank (2) for nitrification of ammonia nitrogen in wastewater that has undergone organic material adsorption process by concentrated nitrification bacteria, and second anoxic acid A mode in which wastewater is sequentially introduced into the reactor 3 and treated; A second anoxic reaction tank (3) for adsorption treatment of organic matter contained in the wastewater by microorganisms (3), an aerobic reaction tank (2) for nitrification of ammonia nitrogen in the wastewater that has undergone organic matter adsorption through concentrated nitrification bacteria, and first anoxic acid The inflow passage is changed to B mode in which wastewater is sequentially introduced into the reactor 1 and treated. Some of the wastewater flowing into the aerobic reaction tank (2) is bypassed to the first anoxic reaction tank (1), the second anoxic reaction tank (3), Part of the wastewater flowing from the aerobic reaction tank (2) to the first anoxic reaction tank (1) or from the aerobic reaction tank (2) to the second anoxic reaction tank (2) is continuously fed to the aerobic reaction tank (2) by an internal circulation pump. In bypassing The mode A and mode B are changed by inflow pumps at intervals of 30 to 60 minutes, and the size of the aerobic reactor 2 is 1.5 to 1.5 to ensure sufficient time for nitrification. In order to increase the denitrification efficiency to 2.0 times, in the A mode, the aerobic reaction tank 2 to the second anoxic reaction tank 3, and in the B mode, the aerobic reaction tank 2 and the first Small-scale wastewater treatment method using a bioadsorption mechanism, characterized in that the internal circulation in the ratio of 1-4Q in an oxygen-free reaction tank (1). delete delete

Images