KR20000061356A - Method of denitrification and denitrification for the purification of wastewater - Google Patents

Abstract

PURPOSE: A process for biologically removing nitrogen and phosphorus in wastewater is provided, which is characterized in that the system can treat smoothly nutrients in spite of a deficient carbon source. And the system cuts down electric power costs by phosphorus uptake in an anoxic tank instead of an aerobic tank. CONSTITUTION: A process for biologically removing nitrogen and phosphorus in wastewater is characterized by comprising the following parts: a first settling tank(10), an anaerobic tank(20), a first anoxic tank(30), a second anoxic tank(40), a second settling tank(50), and an aerobic tank(60). And the system is characteristics of influent distribution(20-30%) to the second anoxic tank(40), internal return from the aerobic tank(60) to the first anoxic tank(30), sludge return(40-60%) from the second settling tank(50) to the anaerobic tank(20), the aerobic tank(60) equipped with media and a nitrogen and phosphorus removal microorganisms(XdPAO) of the first anoxic tank(30).

Description

Biological denitrification and dephosphorization method of wastewater and its apparatus {Method of denitrification and denitrification for the purification of wastewater}

The present invention relates to a wastewater treatment method and apparatus for removing contaminants suspended or dissolved in wastewater. In particular, even when a carbon source is low, a biological treatment method can be used to remove organic matter, nitrogen and phosphorus from wastewater. The present invention relates to a method for biological denitrification and dephosphorization of sewage water and a device thereof.

In recent years, as lakes, reservoirs, and rivers, which have been used as water sources, have deteriorated in water quality due to eutrophication, nitrogen and phosphorus, which are the causes of eutrophication, have to be removed during sewage treatment. Since only the sludge process, which is a secondary treatment, is operated, the nitrogen and phosphorus in question are discharged to the rivers or flowing into lakes and reservoirs as they are almost untreated.

Therefore, not only agricultural return water, but also human waste, food waste discharged from the kitchen to sewage, concentrated inorganic phosphate compounds used in various household detergents, etc. are generated in the waste water to not only eutrophicate the environmental waters with phosphorus and nitrogen There was a problem of promoting the growth of aquatic plants.

In addition, when the nitrogen is released into the environment mainly composed of organic nitrogen and ammonia nitrogen in the waste water, the organic nitrogen and ammonia nitrogen is converted to nitrite in nature, and then become nitrate, which requires a large oxygen demand. There was this.

Therefore, the removal principle of treating nitrogen and phosphorus simultaneously by a biological method will be described to solve such a problem. Biological nitrogen and phosphorus removal principles are independent of each other, and how to properly apply them in the treatment process is a problem.

First, let's look at the reaction of phosphorus. The removal of phosphorus biologically uses the release and intake of phosphorus in the anaerobic and aerobic processes, and the suspended solids are removed from the initial settling tank and the microbial body weight returned by the excess sludge conveying pump in the anaerobic state from the effluent flowing into the anaerobic reactor. As a result, organic matter is ingested and stored, and phosphorus release begins, and phosphorus is removed by accumulating polyphosphoric acid in the body of the microorganism together with the growth of the microorganism in the aerobic state of the subsequent process. That is, ortho-P is released from the poly-P stored in the cell in the anaerobic process, and the polyphosphate accumulated in the cell is a linear bond of the regular phosphoric acid, and the ring of the bond becomes an energy source. . In addition, PO ₄ ⁺ by hydrolysis of the polyphosphate is Glass is released into the liquid, is referred to as the phenomenon of being released (phosphorus release).

At this time, the extracellular organic matter is transferred into the cell by energy, which is called active transport, and the absorbed organic matter is stored as PHB (poly-B-hydroxy buthylate) and then stored in the cell when it is aerobic. PHB is broken down to synthesize ATP, and this energy is absorbed and stored as polyphosphoric acid in cells. At this time, the ingestion of excess phosphoric acid from the solution to synthesize the inorganic phosphoric acid is the excessive intake (lusuary uptake) of phosphorus. Phosphorus biological elimination is achieved by releasing in the form of sludge the microorganisms that ingested excess phosphorus in aerobic state.

Next, let's look at the reaction of nitrogen. Nitrogen components in sewage water can be classified into organic nitrogen (organic-N), ammonia nitrogen (NH ₄ -N), nitrite nitrogen (NO ₂ -N) and nitrate nitrogen (NO ₃ -N), etc. In order to remove nitrogen, a two-stage process, a nitrification process and a denitrification process, is required. In the nitrification step, the nitrate is converted into the form of nitrate under aerobic conditions, and the nitrate is converted to nitrogen gas in the denitrification step. In this case, an organic carbon source is required to supply the carbon for biological synthesis and to supply a hydrogen donor to induce the denitrification process. In other words, by using an open pure oxygen activated sludge treatment process that is treated by microorganisms in an aerobic state, nitrification of nitrogen occurs while simultaneously decomposing organic materials. When the nitrated mixed solution is returned to the anoxic reaction tank in a large amount, nitrogen oxide is removed by the denitrification reaction by the microorganism in the anoxic state, and nitrogen is removed.

The nitrogen removal process includes a nitrification step in which ammonia and organic nitrogen in the influent are changed to nitrate nitrogen and nitrite nitrogen under certain conditions, and the nitrate nitrogen nitrated by the nitrification step is reduced to a treatment system. Denitrification leads to the removal of nitrogen.

As described above, biological treatment processes (hereinafter, referred to as advanced treatment processes) that properly mix and remove nitrogen and phosphorus removal principles at the same time include A ² / O processes, Bandenpho processes, and the University of Cape Town (UCT). Process, VIP (Virginia Initiative Plant) process, etc., which will be described in more detail as follows.

In the A ² / O method, as shown in Figure 1a, the sedimentation treatment in the primary sedimentation tank 100, the inflow water, such as sewage and waste water from which the suspended solids are removed anaerobic reaction tank 200, anoxic reaction tank (300) ), And by discharge through the aerobic reactor 400, the secondary precipitation tank 500, the residence time of the oxygen-free reaction tank 300 takes about 1 hour. In the anoxic reactor 300, there is no dissolved oxygen, but chemically bonded oxygen in the form of nitrate and nitrite is introduced from the aerobic reactor into the nitrified MLSS (Mixed Liquor Suspended Solids: suspension solids mixed solution) to denitrify nitrogen nitrate. By making it so that the phosphorus discharged from the anaerobic reactor 200 is excessively absorbed in the aerobic reactor (400) and in the anaerobic reactor 200 is conveyed sludge of 0.5 times the inflow water from the secondary settling tank 500 Allow inflow.

In addition, the modified Badenpho method, as shown in Figure 1b, to remove the influent water, such as wastewater through the first settling tank 100 for the removal of phosphorus, nitrogen and carbon anaerobic reactor 200, the first anoxic Through the reactor 300, the first aerobic reactor 400, the second anoxic reactor 500, the second aerobic reactor 600 and the second settling tank 700 to be discharged in series, the first The aerobic reaction tank 400 conveys four times the amount of inflow water, and the second settling tank 700 conveys the return sludge of 0.5 times the inflow water to the anaerobic reactor 200.

In addition, the UTC (University of Cape Town) method, as shown in Figure 1c, the anaerobic reactor 200, anoxic reactor 300, an aerobic reactor (400) for the inflow of sewage, such as wastewater through the first settling tank 100 ), Which is processed and discharged in series through the second settling tank 500, and at this time, the anoxic reaction tank 300 is returned to the anaerobic reaction tank 200 at an amount of 1 to 2 times the inflow water, and the aerobic reaction tank 400 is introduced. While conveying 1 to 2 times the amount of water to the oxygen-free reaction tank 300, the second settling tank 500 is returned to the anaerobic tank 200, the return sludge of 0.5 times the inflow water.

In addition, the VIP (Virginia Initiative Plant) method, as shown in Figure 1d, anaerobic reactor 200, anoxic reactor 300, aerobic reactor 400, the inflow of sewage, such as wastewater through the first settling tank 100 , And discharged after treatment through the second settling tank (500), in this case, the anoxic reaction tank (300) conveys 1 to 2 times the amount of inflow to the anaerobic reactor (200), the aerobic reactor (400) and the first In the two-precipitation tank 500, the conveying sludge 1 times the amount of inflow water is returned to the oxygen-free reaction tank 300.

Table 1. Comparison of Characteristics of Domestic and Foreign Wastewater

domestic Oversea Influent Leachate Money waste Influent Leachate Money waste pH 6.5-7.5 7.4-8.1 6.9-8.4 - 3.7-9.0 7.8 Alkailnity 90-180 5,400-7,650 1,845-3,800 - 140-20,900 - SS 47-260 702-854 675-1,625 - 5-18,800 8,290 CODcr 74-228 4,010-4,855 2,025-5,022 208-303 9-90,000 10,580 BOD 60-112 2,854-3,765 1,132-1,620 75-183 2-55,000 - NH4H 10-25 1,474-1,823 398-734 - 0-1,100 844 TN 17-31 1,540-1,899 750-828 24.5-36 0-2,400 1,258 PO4N 0.8-4.4 8.6-16.8 27-55.2 - - 19.4 TP 1.2-6.7 2.5-8.4 41.3-83 7.8-13.4 0-155 236 COD / TN 4.3-7.4 2.1-3.2 2.8-4.1 8.4-8.7 58 or more 8.4

(All units except pH, COD / N and Akalinity are mg / L.)

However, as described above, in the method of removing nutrients in waste water treatment, nitrate nitrogen, which is nitrated in an aerobic reactor, is returned to an acid-free tank, whereby denitrification of nitrate nitrogen occurs and phosphorus released from the anaerobic reactor is excessively absorbed in the aerobic reactor. However, as in Korea (see Table 1 above), sewage with lower organic matter concentration than nitrogen or phosphorus can not be denitrified, so the nitrate nitrogen is not denitrified. When introduced into the anaerobic reactor 10 mg / L or more through the sludge return of the sedimentation tank, the organic matter of the influent is used for denitrification before the release of phosphorus and the biostorage of organic matter occurs, there is a problem that the phosphorus removal efficiency is reduced.

In addition, if the influent wastewater lacks a carbon source, i.e., organic matter, denitrification by denitrifying microorganisms is insufficient, and a return sludge containing a large amount of nitrate nitrogen is returned to the anaerobic reactor, before the release of phosphorus and the biological storage of organic matter. Organic matter in the influent is used for denitrification, and eventually there is a problem in that phosphorus removal efficiency is lowered.

An object of the present invention is to solve the conventional problems as described above, in particular, to reduce the amount of organic matter and sludge production required in the overall process, as well as to reduce the amount of nitrogen nitrate to be transported to reduce the phosphorus removal performance The present invention provides a method and apparatus for biological denitrification and dephosphorization of sewage water to be improved.

In addition, the present invention is capable of removing phosphorus and nitrogen stably regardless of the large and small concentrations of organic matters to nitrogen and phosphorus, as well as biological denitrification of sewage water to shorten the reaction time to stably obtain the desired water quality. The present invention provides a method and a device for dephosphorization.

In order to achieve the above object, the present invention provides a method for biological denitrification and dephosphorization of wastewater, and the denitrification microorganism (X _dPAO ) through nitrogen denitrification microorganism (X _dPAO ) to reduce the amount of organic matter required for the entire process as well as nitrogen nitrate to be returned. It is characterized in that the phosphor can be removed at the same time.

In addition, the present invention is characterized by reducing the treatment capacity to reduce the reaction time and the continuous removal of phosphorus by using nitrate nitrogen as an electron acceptor in an oxygen-free reaction tank.

In addition, the present invention is not only to remove the phosphorus using an anoxic process to reduce the production of sludge, but also to transport the nitrified treated water in the system to reduce the site of the treatment facility to ensure a stable water quality It is to be done.

In addition, the present invention is characterized by reducing the inhibition of nitrification process even in winter by increasing the buffering capacity of microorganisms by employing a media such as biofilm filtration in the latter nitrification process.

1 is a schematic diagram illustrating a general biological denitrification and dephosphorization process.

1A shows an A2 / O process,

Figure 1b shows a Badenpo process,

Figure 1c shows a UCT process,

1D shows the VIP process.

Figure 2 is a schematic diagram showing a biological denitrification, dephosphorization process of the present invention.

Figure 3 is a graph showing the correlation between denitrification and phosphorus removal amount and TBOD.

<Description of the code | symbol about the principal part of drawing>

10: first settling tank 20: anaerobic reactor

30: first anoxic reactor 40: second anoxic reactor

50: second precipitation tank 60: aerobic reactor

Hereinafter, the present invention configured as described above will be described in detail with reference to embodiments according to the technical idea of the biological denitrification, dephosphorization method and apparatus of the waste water. Figure 2 is a schematic diagram showing the biological denitrification, dephosphorization process of the invention, Figure 3 is a graph showing the correlation between denitrification and phosphorus removal amount and TBOD.

Wastewater treatment system of the present invention is the first settling tank 10, anaerobic reactor 20, the first anoxic reactor 30, the second anoxic reactor 40, the second settling tank 50 and aerobic reactor 60 in order The present invention relates to a nutrient removal method including an operating process, which will be described in more detail as follows.

Inlet water flowing into the first settling tank 10 is returned to the second anoxic reaction tank 40 so that general denitrification is performed using the organic material of the influent.

In addition, the inner conveyance 81 is performed from the aerobic reaction tank 60 to the first anoxic reaction tank 30, and the sludge conveyance 71 is performed from the second settling tank 50 to the anaerobic reaction tank 20.

In addition, the amount of inflow water flowing into the first settling tank 10 into the second anoxic reactor 40 is 20 to 30%, and the amount of sludge conveyed from the second settling tank 50 to the anaerobic reactor 20 is It is 50%.

In addition, dephosphorylated microorganism (X _dPAO ) is used in the first anoxic reactor 30.

In the dephosphorization process of the first and second anoxic reactors 30 and 40, phosphorus is removed by using nitrate nitrogen as an electron acceptor without using O ₂ as an electron acceptor.

In addition, the aerobic reactor 60 has a media such as biofilm filtration to increase the buffering capacity of the microorganisms to maintain nitrification performance.

In addition, the first and second anaerobic reaction tanks 30 and 40 have low concentrations of organic matter and when organic matter is accumulated in the microorganisms in the anaerobic reactor 20, which is a preceding process, denitrification and dephosphorization microorganisms as well as general denitrification microorganisms (X _dPAO ). The denitrification and dephosphorization are expressed, and when the concentration of organic matter is high, the denitrification and dephosphorization are expressed by general denitrification microorganisms.

Next will be described in more detail with reference to the embodiment of the present invention configured as described above. These examples are intended to illustrate the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited to these examples.

Figure 2 is a schematic diagram of a device for implementing the method for simultaneously removing the biological nitrogen, phosphorus treatment of sewage and wastewater according to the present invention, 10 is the first settling tank, 20 is the anaerobic reactor, 30 is the first anaerobic reactor, 40 is The second anoxic reactor, 50 is the second settling tank and 60 is the aerobic reactor.

These first settling tank 10, anaerobic reactor 20, the first anoxic reactor 30, the second anoxic reactor 40, the second settling tank 50 and the aerobic reactor 60 is a transfer path (11, 21, 31, 41, 51, 61 are serially communicated and discharged to the outside in the aerobic reactor 60.

First, when the sewage and waste water flows into the first settling tank 10, after the suspended solids are precipitated and removed, the effluent flows into the anaerobic reactor 20. In the anaerobic reactor 20, organic matter is ingested and stored in the body weight of microorganisms returned from the second settling tank 50 through the excess sludge conveying tube 71 in the anaerobic state, and release of phosphorus begins. At this time, the phosphorus release reaction time (retention time) is adjusted in accordance with the properties of the phosphorus compound in water.

After being treated in the anaerobic reactor 20, and introduced into the aerobic reactor 60 through the anoxic reactor, in addition to the growth of the microorganism in the aerobic state in the aerobic reactor 60, polyphosphate is accumulated in the microorganism to remove phosphorus . That is, the microorganisms involved in the removal of phosphorus have the ability to remove a simple enzyme substrate in the anaerobic state in the anaerobic reactor 20, releasing phosphorus while assimilation to the storage product in the cell, and multiple in the aerobic state in the aerobic reactor 60 Phosphorus is removed because it is stored in excess of phosphorus in the form of phosphates.

On the other hand, the aerobic reactor 60 is a process for the treatment of pure oxygen activated sludge to decompose the organic material, in this case, nitrogen is nitrified. At this time, the aerobic reactor 60 is provided after the second settling tank (50) through most of the anaerobic reactor 20, the first and second anoxic reactors 30, 40 and the second settling tank (50) Treated water is introduced while organics and suspended solids are removed, thereby reducing the reaction time (retention time) of the nitrification process. In particular, it is possible to maintain the nitrification performance by increasing the buffering capacity of microorganisms by employing a media such as biofilm filtration in winter. In addition, if necessary, an additional external carbon source may be added to the anoxic reactor to improve denitrification and dephosphorization performance.

Therefore, in order to denitrate, an appropriate amount of organic matter is required. When the concentration of the organic matter is high, general denitrification occurs in the second anoxic reactor 40, and the concentration of organic matter is low and the anaerobic reactor (the previous process) ( In 20), when organic matter is accumulated in a microorganism, not only denitrification microorganism but also denitrification and dephosphorization microorganism may exist. Therefore, when the concentration of organic matter is high, general denitrification microorganisms prevail in the second anoxic reactor 40, and in the anaerobic reactor 20 together with nitrification in the aerobic reactor 60 of the second sedimentation tank 60 in the subsequent stage. Phosphorus release is again ingested and removed.

On the other hand, only the portion to be denitrated in the nitrate in the nitrification step is returned to the first anoxic reaction tank 30 (about 100%) to denitrify, so that denitrified microorganisms in the anaerobic reactor 20 by the nitrate nitrogen in the conveying sludge Inhibition of activity can be minimized. Therefore, the phosphorus is more easily released in the anaerobic reactor 20, and the phosphorus can be ingested through the anaerobic reactor. At this time, by using the electron acceptor lacking in the first anoxic reaction tank 30 as nitrate nitrogen to supply oxygen in the nitrification process, the continuous phosphorus removal occurs.

In addition, when the nitrified microorganism liquid in the aerobic reactor 60 is returned to the first anoxic reactor 30 containing dephosphorus and denitrified microorganism (X _dPAO ) together with the nitrification process in the aerobic reactor 60, in an anoxic state As the nitric oxide is reduced, the denitrification process as well as the denitrification process discharged to the nitrogen gas in the air are simultaneously performed, thereby reducing the concentration of nitrate nitrogen returned. In addition, by using the first anoxic reactor 30 instead of the aerobic reactor 60 for the removal of phosphorus it is possible to reduce the power required to drive the aerobic reactor 60 and sludge production. In addition, the dephosphorization process by denitrification and dephosphorization microorganism (X _dPAO ) in the anoxic reaction tank removes phosphorus by using nitrate nitrogen as an electron acceptor without using O ₂ as an electron acceptor. Therefore, when there is not enough nitrate nitrogen to be conveyed according to the characteristics of the incoming wastewater, the microorganism which uses the nitrate nitrogen returned to the anoxic reactor as an electron acceptor for dephosphorization in the anoxic reactor is reversed. In addition, since the excess nitrate nitrogen is independently removed through the normal denitrification microorganisms, the sludge returned to the settling tank is returned only a small amount of nitrate nitrogen so as not to affect the phosphorus emission phenomenon in the anaerobic reactor 20. do.

As described above, the simultaneous removal of nitrogen and phosphorus in an anaerobic reaction tank is caused by denitrification and dephosphorization microorganism (X _dPAO ) due to the use of organic matter accumulated in the anaerobic reactor 20 (easy biodegradable COD). Denitrifying microorganisms by using slowly biodegradable COD and organic matter fermented in anaerobic reactor 20 through denitrification microorganisms are used for dephosphorization microorganisms and denitrification microorganisms. This will reduce the amount of organic matter from nitrogen and phosphorus removed. Therefore, as shown in FIG. 3, the existing processes also exhibit good denitrification and dephosphorization performance in a high TBOD state, but a high denitrification and dephosphorization amount by this process in a low TBOD state.

In addition, the biological storage of the organic matter in the anaerobic reactor 20 and the use of organic materials by general denitrification microorganisms in the anaerobic reactor, such that the aerobic reactor 60 is able to perform only nitrification process rather than the oxidation of organic matter sequentially. The overall capacity can be reduced.

On the other hand, the second settling tank 50 is for the precipitation of microorganisms, denitrifying microorganisms, dephosphorus microorganisms ingesting the generated organic material, to control the activated sludge concentration (MLSS: Mixed Liquor Suspended Solid) in the aerobic reactor (60) The conveying sludge is conveyed to about 50%. Partial sludge is discarded in the second settling tank 50, and the size of the second settling tank 50 is increased to about 1 hr larger than that of a general activated sludge in order to reduce the influence of the return water and endogenous denitrification in the sludge and continuous It will lead to sludge settling. At this time, the conveying amount of the conveying sludge conveyed to the aerobic reactor 60 in the second settling tank (50) by adjusting the conveying rate according to the concentration of the organic material to adjust the reaction time (retention time) by the dissolved oxygen of high concentration do.

Therefore, since the treated water passing through the second anoxic reaction tank has passed through the second settling tank 50, microorganisms and the remaining suspended matter and organic matter caused by the suspended matter are not supplied to the aerobic reactor 60 so that ammonia nitrogen and traces Only organic matter of nitrification and organic matter oxidation are respectively.

The concentration change of each reaction tank of the present invention is as shown in Table 2. When the operation of the present invention will be described with reference to Table 2.

Step factor Inflow First settling tank Anaerobic reactor 1,2 anoxic reactor Second settling tank Nitrification process (final runoff) HRT (hr) - 2 One 2-3 4 1-2 BOD (mg / L) 100 70 - - <10 <5 COD (mg / L) 250 173 - - <30 <15 SS (mg / L) 180 108 - - <10 <5 TN (mg / L) 40 36 - - 30.5 <15 NH4N (mg / L) 31 28 - - - <1 NO3N (mg / L) - - - - - 14.2 TP (mg / L) 5.6 5 - - <1 <1 SP (mg / L) 4.0 3.6 7.3 1.1 - <1

The abbreviation used in the present invention is as follows.

HRT: Hydraulic Retention time

BOD: Biological Oxygen Demand Biochemical Oxygen Demand

COD: Chemical Oxygen Demand

SS: Suspended Solid Suspended

TN: Total Nitrogen Total Nitrogen

NH ₄ N: Ammonium Nitrogen Ammonia Nitrogen

NO ₃ N: Nitrate Nitrogen Nitrate Nitrogen

TP: Total Phosphorus

SP: Soluble Phosphorus Soluble

SVI: Sludge Volume Index Sludge Capacity Index

First, the concentration of microorganisms used in this process is 3000 mg / L (MLVSS = 2,100) of activated sludge concentration, and the nutrient concentration required for cell synthesis of microorganisms is about 5% of BOD removed from nitrogen, phosphorus phosphorus 1%. In addition, the first settling tank has a BOD removal efficiency of 30%, an SS removal efficiency of 40%, and a TN and TP removal efficiency of 10%.

The anaerobic reactor in which phosphorus release takes place is that the nitrate nitrogen returned from the second settling tank before the phosphorus release occurs is used for denitrification and dephosphorization from the anoxic tank so that phosphorus release rate SPRR in the anaerobic reactor is not affected. Is 1.1 mgP / gVSS per hour and HRT is 1 hour, so the concentration of phosphorus released from the anaerobic reactor An eff. P = In Phosphorus concentration + Phosphorus concentration returned + Phosphorus discharge concentration. P is 7.3 mg / L.

In addition, the concentration of nitrate nitrogen (NO ₃ N) flowing into the first and second anoxic reaction tank = anaerobic tank effluent (100%) + nitrification process return water (100% internal transport) + sludge transport (50%) = (nitrification Possible amount-amount of nitrogen required for cell synthesis) /2.5, and the concentration of nitrate nitrogen (NO ₃ N) flowing into the first and second anaerobic reactors is (36-3.5) /2.5 = 14.2 mg / L.

In addition, the phosphorus concentration flowing into the first and second anaerobic reaction tanks = anaerobic tank effluent (100%) + nitrification return water (100% internal return), and the phosphorus concentration flowing into the first and second anoxic reactors is (7.3 + 1.0 ) / 2 = 4.15 mg / L. In addition, the excess intake rate SPUR is 0.84 mgP / gVSS per hour and HRT is 2 hours, so the required amount of nitrate nitrogen needed to remove phosphorus Δ (NO ₃ N) / Δ (P) = 4.6 gNO ₃ Nreq./gPrem. Accordingly, the phosphorus removal possible amount is 14.2 / 4.6 = 3.04 mgP / L, and the outflow phosphorus concentration of the first and second anaerobic tanks is 4.15-3.04 = 1.1 mg / L, and the first and second anoxic reactors effluent nitrate nitrogen The concentration is 14.2-3.04 * 4.6 = 0.216 so that only a small amount of nitrate nitrogen is not detected in the first and second anoxic reactors.

In addition, the sludge amount generated by removing the phosphorus in the anoxic tank according to the present invention is 0.2 ~ 0.46 gVSS / gCOD is reduced about 30 ~ 40% than the sludge amount 0.35 ~ 0.67 gVSS / gCOD generated to remove phosphorus in the general aerobic tank You can do it.

In addition, the present invention, as shown in Figure 3, compared to the existing process, the demassation + phosphorus removal amount is increased by about 7 ~ 10 mg / L has a high denitrification and dephosphorization performance even in a small organic carbon source. At this time, the organic carbon source saved by the present invention, assuming that the organic material required for denitrification and phosphorus removal of nitrate nitrogen is 5 mgCOD, 7 ~ 10 mg (N + P) / L * 5 (mgCOD / L) / mg ( N + P) rem = 35 ~ 50 mgCOD / L

Accordingly, the second precipitation tank has an SVI of 80 to 100, an endogenous denitrification rate SDNRe of 0.5 mgN / gVSS per hour, a sludge height of 0.5m, a sludge HRT of 0.5 hours, and a sludge concentration of 10,000 mg / L (VSS = 7500). mg / L), the amount of nitrate nitrogen removed in the second settling tank = endogenous denitrification rate * sludge concentration * sludge HRT = 0.5 * 7.5 * 0.5 = 1.875 mg / L.

In addition, in the aerobic reactor, the nitrification process has a porosity of 50% when the biofilm is applied, an air injection rate per unit volume of 3.97 m ³ air / m ³ = 0.97 m ³ O 2 / m ³ , and a nitrification rate of 1.0 N / m3 / d to 41.7 mgN / L per hour. At this time, the nitrification concentration of the biofilm filtration is 26.3 mg / L, the biofilm filtration EBCT is 0.58 to 1 hour, the HRT of biofilm filtration is performed once every 5 days intervals about 30 minutes.

As described above, the biological denitrification and dephosphorization method of the sewage water of the present invention and the denitrification method can be carried out smoothly even when the carbon source is limited, while reducing the production of sludge and obtaining stable water quality in a short residence time. The effect is that the reliability of the wastewater treatment can be obtained.

In addition, the present invention is to perform the phosphorus removal in the anoxic reaction tank instead of the aerobic reaction tank to be able to reduce the power required to drive the aerobic reactor is to reduce the maintenance cost.

Claims (12)

In the biological denitrification, dephosphorization method of sewage water, Method for biological denitrification and dephosphorization of sewage water, characterized in that it comprises a step of operating in the order of the first settling tank, anaerobic reactor, the first anoxic reactor, the second anoxic reactor, the second settler and the aerobic reactor. The method of claim 1, Biological denitrification and dephosphorization method of sewage water, characterized in that the inflow water flowing into the first settling tank is returned to the second anoxic reactor. The method of claim 1, A method for biological denitrification and dephosphorization of sewage water, characterized in that the internal transport is carried out from the aerobic reactor to the first anoxic reactor, and sludge conveyed from the second settler to the anaerobic reactor. The method according to claim 1 or 3, Denitrification, dephosphorization microorganism (X _dPAO ) is used in the first anoxic reactor, biological denitrification, dephosphorization method of the wastewater. The method according to claim 1 or 3, The dephosphorization process in the first anoxic reactor is a biological denitrification, dephosphorization method of sewage water, characterized in that to remove phosphorus using nitrate nitrogen as an electron acceptor. The method according to claim 1 or 3, The aerobic reactor is a biological denitrification, dephosphorization method of the wastewater, characterized in that it comprises a media (media) such as biofilm filtration. The method of claim 1, When the concentration of organic matter is low and organic matter is accumulated in the microorganism in the anaerobic reactor 20, the denitrification and dephosphorization microorganism (X _dPAO ) is expressed as well as the denitrification microorganism, and the concentration of organic matter is high. In the case of biological denitrification, dephosphorization method of the wastewater, characterized in that the denitrification and dephosphorization phenomenon is expressed by the general denitrification microorganism in the second anoxic reactor. The method according to claim 1 or 2 or 3, Biological denitrification and dephosphorization method of sewage waste water, characterized in that the amount of inflow of water flowing into the second anaerobic reaction tank is 20 ~ 30%, sludge conveyed amount from the second settling tank to the anaerobic reaction tank is 40 ~ 60%. In biological denitrification and dephosphorization of sewage water, Biological denitrification and dephosphorization apparatus of sewage water, characterized in that it comprises a first settling tank, anaerobic reactor, the first anoxic reactor, the second anoxic reactor, the second settler and the aerobic reactor. The method of claim 9, Biological denitrification and dephosphorization apparatus of sewage water, characterized in that 20 to 30% of the influent flowing into the first settling tank is returned to the second anoxic reactor. The method of claim 9, Biological denitrification and dephosphorization apparatus of sewage water, characterized in that the internal transport is carried out from the aerobic reactor to the first anoxic reactor, and sludge conveyed from the second settling tank to the anaerobic reactor. The method according to claim 9 or 11, The aerobic reactor is a biological denitrification, dephosphorization apparatus of the wastewater, characterized in that provided with a membrane (media) such as biofilm filtration.