KR19990030405A - Wastewater Purification Using Distribution Inflow - Google Patents

Abstract

By effectively minimizing nitrogen and phosphorus and maximizing phosphorus release by maximizing organic matter in wastewater, nutrients can be treated efficiently and at a low price, and the size of denitrification reactor can be reduced by high denitrification and biological phosphorus release rate. In addition, a method for purifying wastewater which can reduce the concentration of nitrogen and phosphorus below a regulated concentration is disclosed. In a first preferred embodiment of the present invention, the first anaerobic tank, the second anoxic tank, the anaerobic tank, the non-aerobic reaction tank, the aeration reaction tank, and the precipitation tank are configured in order, and the sludge is returned from the precipitation tank to the first anoxic tank. In the first anoxic tank, the concentration of nitrate contained in the sludge is reduced by using a denitrification reaction by endogenous breathing of microorganisms, and the inflow wastewater is injected into the second anoxic tank and the anaerobic tank in a distribution ratio according to an appropriate ratio. The second anaerobic tank performs denitrification of the influent wastewater and releases some of the phosphorus contained in the influent wastewater. In the anaerobic tank, the organic matter is adsorbed using microorganisms to release the remaining phosphorus, and In the aeration tank, denitrification and nitrification are performed, respectively.

Description

Wastewater Purification Using Distribution Inflow

The present invention relates to a method for advanced treatment of sewage and wastewater, and more particularly, to a method for purifying wastewater that can effectively remove organic matter, nitrogen and phosphorus contained in organic wastewater such as municipal sewage, livestock wastewater and industrial wastewater. It is about.

In general, nutrients are inorganic elements necessary for the growth and growth of microorganisms causing organic decomposition, among which nitrogen compounds and phosphates are elements that must be continuously supplied for biological cell formation and life energy acquisition. However, eutrophication occurs when nutrients such as nitrogen and phosphorus increase in rivers, coastal seas and lakes. The eutrophication activates the production of nutrient-containing organisms, thereby changing the ecosystem of nature, causing red tide in the sea area, and algae, etc., in the appeal cause abnormal growth.

This process proceeds smoothly in nature, but when large amounts of domestic sewage, livestock wastewater, and plant drainage flow in, nutrients increase excessively, thus suspending substances are mixed in a large amount, exceeding the natural self-purifying ability. As a result, eutrophication is rapidly progressing and, in severe cases, odors are caused by decay and water pollution is promoted. Therefore, these nutrients in the wastewater should be removed before entering the lake or river, and many studies have been made to efficiently remove them.

In Korea, most sewage treatment and livestock wastewater treatment methods rely on activated sludge method. 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.

Therefore, most of the purpose of wastewater treatment for the protection of the water system is to remove nitrogen and phosphorus, and it is very important to reduce point pollutants that contaminate water systems in the present situation where it is urgent to develop a process that meets the regulatory concentration which will be strengthened in the future. Do.

Methods for biologically treating nitrogen in wastewater containing a large amount of nutrients are largely classified into pre-denitrification and post-denitrification processes.

First, the post-denitrification process has the advantage that the size of the reactor is small and the water quality of the effluent is uniform. However, since the denitrification tank is located in the latter part of the nitrification tank, the denitrification tank has a disadvantage in that it is uneconomical because the amount of organic matter that is easily decomposed is small and an electron donor such as methanol must be injected separately from the outside.

On the other hand, in the pre-denitrification process, since the organic material in the influent wastewater is used as the electron donor required for the denitrification, there is an advantage in that there is no need to separately inject external electron artefacts when the organic material in the influent water is large. However, there is a problem that the organic matter in the influent wastewater is less denitrification efficiency than organic matters such as methanol. In addition, since the nitriding tank is located in the latter part of the denitrification tank, it is necessary to convey the nitrate formed in the nitriding tank to the denitrification tank, and in this case, the conveying amount is generally about four times the inflow water. For this reason, since the reaction tank of the pre-denitrification process becomes very large relative to the reaction tank of the post-denitrification process, there is a disadvantage in that the installation cost becomes large. If there is little organic matter in the influent water, there is a problem that the external organic matter should be supplied because nitrogen treatment is not sufficiently performed by the above-described denitrification process.

If the concentration of phosphorus in the wastewater is high, the phosphorus release and uptake reaction of certain microorganisms can treat the phosphorus in the wastewater. In this case, release of phosphorus in the anaerobic state is preceded and excess intake of phosphorus is achieved in the subsequent aerobic state. Phosphorus release is highly related to the concentration of electron acceptors, such as dissolved oxygen or nitrates, and the concentration of organic acids, which are electron donors in the influent, so that the removal efficiency of phosphorus is high when there is no electron acceptor and the concentration of organic acids in the influent is high (Ref. Richard I. Sedlak). (1991), Phosphorus and Nitrogen Removal Municipal Wastewater, LEWIS PUBLISHERS: Clifford W. Randall, Ph. D., Design and Retrofit of Wastewater Treatment Plants for Biological Nutrient Removal, Water Qulity Management Library, Vol 5, Technomic publishing Co.). When the concentration of organic acid in the influent is low, by supplying the organic acid from the outside can increase the release rate of phosphorus to improve the biological phosphorus removal efficiency.

However, in order to remove nitrogen and phosphorus from sewage or waste water, only an anaerobic tank is introduced at the front of the treatment process to induce phosphorus release, but this is carried out in the anaerobic tank, and in the process, dissolved oxygen, nitrite ( the release rate of phosphorus is reduced by the electron acceptor, such as -N) ^- NO ₂ ^- -N) and nitrate (NO _3. Therefore, when denitrification and phosphorus are released in one reactor, there is a disadvantage in that the use of organic materials used as electron donors for denitrification and dephosphorization is very poor.

The present invention has been made to solve the above-mentioned conventional problems, an object of the present invention is to introduce the sludge conveyed from the settling tank into the first anoxic tank and by discharging wastewater into the second anoxic tank and anaerobic tank to treat the electrons, The present invention provides a method of purifying wastewater that can effectively treat nutrients at a low cost by effectively minimizing the system and maximizing phosphorus discharge by maximizing organic matter in the wastewater.

Another object of the present invention is to provide a method for purifying wastewater which can reduce the size of the denitrification reactor due to the high rate of denitrification and biological phosphorus release and can reduce the concentration of nitrogen and phosphorus below the regulated concentration.

1 is a schematic view showing a wastewater purification process according to a first embodiment of the present invention;

Figure 2 is a schematic diagram showing a purification process of wastewater according to a second embodiment of the present invention,

3a and 3b is a schematic view showing a wastewater purification process according to a third embodiment of the present invention, and

4A and 4B are schematic diagrams illustrating a purification process of wastewater according to a fourth preferred embodiment of the present invention.

Explanation of symbols for the main parts of the drawings

1: anaerobic tank and anaerobic tank (= tubular flow reactor)

1a: first anoxic tank (= completely mixed reactor)

1b: first anoxic tank (= completely mixed reactor)

1c: anaerobic tank 2: non-aerobic (anoxic) reactor

2a: First intermittent aeration reactor 3: Aeration (exhalation) reactor

3a: second intermittent aeration reactor 4: settling tank

5: external organic carbon source 6: post-aeration tank (= re-aeration tank)

In order to achieve the above object, the present invention,

The first anoxic tank, the second anoxic tank, the anaerobic tank, the non-aerobic reactor, the aeration reactor and the settling tank are carried out in order, and the sludge is returned from the settling tank to the first anoxic tank, and in the first anoxic tank, denitrification by endogenous breathing of microorganisms is carried out. By reducing the concentration of nitrates contained in the sludge, the inflow of wastewater into the second anaerobic tank and the anaerobic tank in a distribution ratio according to the proper ratio, the second anoxic tank in the organic matter in the inflow wastewater to the electron donor Conducts denitrification of the influent wastewater and releases some of the phosphorus contained in the influent wastewater, and in the anaerobic tank, the organic matter is adsorbed using microorganisms to release the remaining phosphorus, and the non-aeration reactor and the aeration reactor In the purification room of the wastewater, characterized in that the denitrification and nitrification are respectively performed It provides.

The anoxic tank and the anaerobic tank may be operated as one reactor in continuous stirred tank reactor (CSTR) or tubular flow (plug-flow).

The non-aeration tank and the aeration tank can be operated in the form of an intermittent aeration tank, the non-aeration reaction tank, the aeration reaction tank and the intermittent aeration tank is provided with an attachment carrier or medium.

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

1 is a schematic diagram showing a wastewater purification process according to a first embodiment of the present invention.

1, the apparatus for performing the waste water purification process according to the first embodiment of the present invention is a first anaerobic tank (1a), a second anoxic tank (2a), anaerobic tank (1c), non-aerobic reactor (2) , Aeration reactor 3 and precipitation tank 4. The operation method of the wastewater purification apparatus configured as described above is continuously and repeatedly operated in the form as indicated by the arrow in FIG. 1.

First, the sludge precipitated in the settling tank 4 is returned to the first anoxic tank 1a for denitrification by endogenous breathing, and then transferred to the second anoxic tank 1b for denitrification using organic materials in the wastewater. Complete and release of some phosphorus is induced. Thereafter, it is transferred to the anaerobic tank 1c and the release of phosphorus (= dephosphorization reaction) using organic matter in the wastewater is completed.

On the other hand, the inflow wastewater is injected into the second anaerobic tank 1b and the anaerobic tank 1c in an appropriate ratio distribution manner. During sludge transport nitrate (NO ₃ ^- -N) it is also conveyed together, which enables the first anoxic tank (1a) and the second to denitrification in the anoxic tank (1b) maintained at a full anaerobic anaerobic tank (1c). Denitrification in the second anaerobic tank 1b allows the organic matter in the influent to flow into the distribution type, and in the anaerobic tank 1c, microorganisms adsorb organic matter in the incoming wastewater and allow phosphorus to proceed.

The removal of nitrate nitrogen contained in the sludge returned through the anaerobic tanks (1a, 1b) disposed in front of the anaerobic tank (1c) ensures that there is no inhibition of nitrate nitrogen upon the release of phosphorus in the subsequent anaerobic tank (1c), and the influent wastewater The organic material in the second anoxic tank 1b is used as an electron donor when denitrification and in the anaerobic tank 1c as an organic material for releasing phosphorus to improve nitrogen and phosphorus removal efficiency. In the subsequent non-aeration reactor (2) and the aeration reactor (3), denitrification and nitrification proceed, respectively, and the electron acceptor in the aeration reactor (2) uses the nitrate produced in the aeration reactor (3), which is caused by internal circulation. It is sent to the non-aeration reactor (2).

2 is a schematic diagram showing a purification process of wastewater according to a second preferred embodiment of the present invention.

2, the apparatus for performing the wastewater purification process according to the second preferred embodiment of the present invention is configured similarly to the wastewater purification apparatus according to the first embodiment except that the anaerobic tank and the anaerobic tank are integrated. do.

That is, the apparatus for performing the wastewater purification process according to the second embodiment of the present invention includes an anaerobic tank and anaerobic tank (1), non-aeration reaction tank (2), aeration reaction tank (3) and settling tank (4). The operation method of the wastewater purification device configured as described above proceeds similarly to the wastewater purification process according to the first embodiment except for the wastewater treatment method in the anaerobic tank and the anaerobic tank 1.

The flow in the anaerobic and anaerobic tank 1 is in the form of a plug-flow, where the wastewater flows through the structure and the concentration of the substance varies depending on the contact time. When the initial wastewater and the return sludge flow into the anaerobic and anaerobic tank (1), as the contact time increases, the concentration decreases gradually as the nitrate is degassed by being used as an electron acceptor of microorganisms by using endogenous respiration followed by organic matter in the wastewater. Anaerobic conditions are formed. That is, the concentrations of nitrates and nitrites become very low. The point at which anaerobic conditions are formed is different depending on the properties of the incoming wastewater, and the point at which anaerobic conditions are formed is the optimal point where the influent wastewater is distributed and injected. Therefore, when the anaerobic and anaerobic tank 1 is composed of a single tubular flow structure, the point of distribution inflow can be varied according to the characteristics of the wastewater. Organics in the wastewater injected under anaerobic conditions maximize biological release.

3A and 3B are schematic diagrams illustrating a purification process of wastewater according to a third preferred embodiment of the present invention.

First, referring to FIG. 3A, an apparatus for performing a wastewater purification process according to a third exemplary embodiment of the present invention includes a first anaerobic tank 1a, a second anoxic tank 2a, an anaerobic tank 1c, and a first intermittent aeration tank. (2a), a second intermittent aeration tank 3a, a post aeration tank 6 and a precipitation tank 4 are included. At this time, the post-aeration tank 6 may be installed when necessary and may be omitted when the wastewater treatment is sufficient only for the intermittent reaction tank. The operation method of the wastewater purification apparatus configured as described above is continuously and repeatedly operated in the form as indicated by the arrow in FIG. 3A.

First, the sludge precipitated in the settling tank 4 is returned to the first anoxic tank 1a for denitrification by endogenous breathing, and then transferred to the second anoxic tank 1b for denitrification using organic materials in the wastewater. Complete and release of some phosphorus is induced. Thereafter, it is transferred to the anaerobic tank 1c and the release of phosphorus (= dephosphorization reaction) using organic matter in the wastewater is completed.

On the other hand, the inflow wastewater is injected into the second anaerobic tank 1b and the anaerobic tank 1c in an appropriate ratio distribution manner. In the first intermittent aeration tank 2a and the second intermittent aeration tank 3a, air is injected in the form of aeration and non-aeration, and the aeration and non-aeration times are 1 hour / 1 hour, 2 hours / 2 hours and It can be freely adjusted to 1 hour / 2 hours.

Reactors (2a, 3a) operated by the intermittent aeration method can control the injection of air in one reactor to maintain aeration and non-aeration conditions at the same time, nitrification and denitrification can be made at the same time, steady-state As it is not a dynamic state, it is possible to cope with changes in the influent flow rate and concentration. In addition, there is a merit that the transfer rate of dissolved oxygen in water is greater due to the large difference in dissolved oxygen concentration according to the concentration gradient when operating in a non-aeration method (see Patent Publication 97-20986, Multistage Intermittent Aeration Activated Sludge). Nitrogen and phosphorus removal by system).

Next, referring to FIG. 3B, the wastewater treatment process shown in 3B is the same as the operation of the wastewater treatment process shown in FIG. 3A, except that the external organic carbon source 5 is supplied into the second intermittent aeration tank 3a.

That is, when the organic matter of the wastewater is depleted in the second intermittent aeration tank 3a and the denitrification reaction is suppressed during non-aeration, an external organic carbon source 5, which is an external electron donor, is injected and operated. Injection of the external organic carbon source 5 increases the efficiency of denitrification and dephosphorization. As the external organic carbon source 5 to be injected, dissolved organic matter produced by fermentation of organic acid, food or organic living waste of acetate, methanol, propionic acid, livestock wastewater and municipal sewage sedimentation solids can be used.

In case of using acetate, methanol, propionic acid, etc. as the external organic carbon source (5), it causes an economic burden, but is very effective in removing nitrogen and phosphorus from waste water. On the other hand, when using organic acids generated by livestock wastewater, sedimentation solids of municipal sewage or organic living wastes as external organic carbon sources (5), the effect of two-trillion trillion on the recycling aspects of resources and nutrient treatment of wastewater is achieved. Can be.

4A and 4B are schematic diagrams illustrating a purification process of wastewater according to a fourth preferred embodiment of the present invention.

First, referring to FIG. 4A, an apparatus for performing the wastewater purification process according to the fourth preferred embodiment of the present invention is similar to the wastewater purification apparatus according to the third embodiment except that the anaerobic tank and the anaerobic tank are integrated. Is configured.

That is, the apparatus for performing the waste water purification process according to the fourth embodiment of the present invention is an anaerobic tank and anaerobic tank (1), the first intermittent aeration tank (2a), the second intermittent aeration tank (3a), the post-aeration tank (6) and A settling tank 4. The operation method of the wastewater purification apparatus configured as described above proceeds similarly to the wastewater purification process according to the third embodiment except for the wastewater treatment method in the anaerobic tank and the anaerobic tank 1.

The flow in the anaerobic and anaerobic tanks (1) is in the form of a plug-flow, where the wastewater flows through the structure and the concentration of the substance varies depending on the contact time, and the point of distribution influent can be changed according to the nature of the wastewater. Can be.

Next, referring to FIG. 4B, the wastewater treatment process shown in 4B is the same as the operation of the wastewater treatment process shown in FIG. 4A except that the external organic carbon source 5 is supplied into the second intermittent aeration tank 3a.

That is, when the organic matter of the wastewater is depleted in the second intermittent aeration tank 3a and the denitrification reaction is suppressed during non-aeration, an external organic carbon source 5, which is an external electron donor, is injected and operated. As the external organic carbon source 5 to be injected, dissolved organic matter produced by fermentation of organic acid, food or organic living waste of acetate, methanol, propionic acid, livestock wastewater and municipal sewage sedimentation solids can be used.

On the other hand, in all the wastewater purification processes of the present invention as described above, the amount of microorganisms is increased in the non-aeration reaction tank 2, the aeration reaction tank 3, the first intermittent aeration tank 2a and the second intermittent aeration tank 3a. In order to do so, it may be treated with an attachment carrier or a medium. As the carrier and the medium provide a surface on which the microorganisms can grow, the growth of more microorganisms can increase the treatment efficiency of organic matter and nutrients.

According to the purification step of the wastewater according to the present invention as described above, it is possible to maximize the treatment of nitrogen and phosphorus which is the main cause of eutrophication. That is, the efficiency of denitrification and dephosphorization can be improved by maximally utilizing the amount of organic matter determined by the characteristics of the wastewater to remove nitrogen and phosphorus. In addition, the use of an external organic carbon source allows for more complete treatment, and the use of organic acids from livestock wastewater, municipal sewage sediment solids, or food or organic living wastes has high value for recycling.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (12)

The first anoxic tank, the second anoxic tank, the anaerobic tank, the non-aerobic reactor, the aeration reactor and the settling tank are carried out in order, and the sludge is returned from the settling tank to the first anoxic tank, and in the first anoxic tank, denitrification by endogenous breathing of microorganisms is carried out. By reducing the concentration of nitrates contained in the sludge, the inflow of wastewater into the second anaerobic tank and the anaerobic tank in a distribution ratio according to the proper ratio, the second anoxic tank in the organic matter in the inflow wastewater to the electron donor Conducts denitrification of the influent wastewater and releases some of the phosphorus contained in the influent wastewater, and in the anaerobic tank, the organic matter is adsorbed using microorganisms to release the remaining phosphorus, and the non-aeration reactor and the aeration reactor In the purification room of the wastewater, characterized in that the denitrification and nitrification are respectively performed . The method of claim 1, wherein the electron acceptor in the non-aeration reactor is a nitrate that is generated in the aeration reactor and transferred to the non-aeration reactor by internal circulation. The method for purifying wastewater according to claim 1 or 2, wherein the non-aeration reaction tank and the aeration reaction tank are provided with an attachment carrier or a medium. Anaerobic tank and anaerobic tank, non-aerobic tank, aeration tank and sedimentation tank, in order to return the sludge from the sedimentation tank to the anaerobic tank and anaerobic tank, the inflow wastewater is injected into the anaerobic tank and anaerobic tank, endogenous microorganisms in the anaerobic tank and anaerobic tank Denitrification by respiration is used to reduce the concentration of nitrates contained in the sludge, and at the same time, denitrification of the influent wastewater is carried out using an organic material in the influent wastewater as an electron donor and phosphorus contained in the influent wastewater. And denitrification and nitrification are performed in the non-aeration reactor and the aeration reactor, respectively. 5. The method of claim 4, wherein the anaerobic and anaerobic tanks are operated as a single reactor with tubular plug-flow. In the order of the first anoxic tank, the second anoxic tank, the first intermittent aeration reactor, the second intermittent aeration reactor and the settling tank, sludge is returned from the settling tank to the first anoxic tank, and in the first anoxic tank, Denitrification is used to reduce the concentration of nitrates in the sludge, and the inflow wastewater is injected into the second anaerobic tank and the anaerobic tank in a distribution ratio according to an appropriate ratio. In the second anoxic tank, the organic matter in the influent wastewater is introduced. Denitrification of the influent wastewater is carried out using an electron donor to release some of the phosphorus contained in the influent wastewater. In the anaerobic tank, the organic matter is adsorbed using microorganisms to release the remaining phosphorus, and the first intermittent aeration is carried out. In the reaction tank and the second intermittent aeration reactor, the air is injected in the form of aeration and non-aeration Waste water purification method characterized in that. 7. The method of claim 6, wherein a post aeration tank is further provided between the second intermittent aeration reactor and the settling tank. 8. The method of claim 6 or 7, wherein an external organic carbon source is injected into the second intermittent aeration reactor. 8. The method of claim 6 or 7, wherein the first intermittent aeration reactor and the second intermittent aeration reactor are provided with an attachment carrier or a medium. Anaerobic tank and anaerobic tank, the first intermittent aeration reactor, the second intermittent aeration reactor and the settling tank in order, the sludge is returned from the settling tank to the anaerobic tank and anaerobic tank, the inflow wastewater is injected into the anoxic tank and anaerobic tank, the anoxic tank and In the anaerobic tank, the denitrification reaction by endogenous respiration of microorganisms is used to reduce the concentration of nitrate contained in the sludge, and at the same time, the denitrification reaction of the influent wastewater is carried out by using the organic material in the influent wastewater as an electron donor and the influent wastewater. And releasing phosphorus contained in the air, wherein air is injected into the first intermittent aeration reactor and the second intermittent aeration reactor in the form of aeration and non-aeration. The method of claim 10, wherein a post aeration tank is further provided between the second intermittent aeration reactor and the settling tank. 12. The method according to claim 10 or 11, wherein the anoxic tank and the anaerobic tank are operated as a single reactor having a tubular flow type.