KR20010025729A - A method for simultaneous removal of nitrogen and phosphorus in the sewage and waste water - Google Patents

Abstract

PURPOSE: Provided is an advanced wastewater treatment method for removing nitrogen and phosphate simultaneously, which is characterized in that a Plug Flow Reactor separator(2) operated under anoxic state is adopted as a bio-adsorption basin, RIDs are installed in a nitrification basin(6), HBC or RID is installed in a stabilization basin(12) causing luxury-uptake of phosphates by microorganisms for shortening HRT and minimizing operation cost. CONSTITUTION: The system consists of: a PFR separator(2) in which return sludge(22) from a final settling basin(14) is adsorbed biologically under anoxic condition; a primary settling basin(4) in which liquid/solid separation of mixed liquor that is pretreated in the PFR separator is carried out; a nitrification basin(6) which supernatant separated in the primary settling tank and return sludge(18) from the final settling tank flow into, and ammonia is oxidized to nitrite by RIDs; a preliminary anoxic basin(8) into which return sludge(20) from the final settling tank and sedimental sludge separated in the primary settling tank flow, so that NOx-N contained in the return sludge is denitrified and microorganisms release excess phosphate from their cell tissues to mixed liquor; an anoxic basin(10) in which nitrified supernatant flowed from the nitrification tank and denitrified mixed liquor flowed from the preliminary anoxic basin are mixed, and then complete denitrification is carried out; a stabilization basin in which remaining organics and ammonia are completely oxidized, and also luxury up-take of phosphates into cell tissues of microorganisms happens; the final settling basin in which microorganism sludge is settled for return sludge(22, 18, 16) and excess sludge is discarded. In this system, PSA(Pressure Swing Adsorption) type oxygen generator is optionally installed in the stabilization basin for increasing oxygen transmission efficiency so that HRT is reduced drastically and deodorizing effect can be accompanied. Further, in front of either the final settling basin or the PFR separator, chemical coagulants such as Al3+, Fe3+ are optionally injected to accelerate flocculation and remove soluble phosphates so that the primary settling basin can be operated stably.

Description

METHODS FOR SIMULTANEOUS REMOVAL OF NITROGEN AND PHOSPHORUS IN THE SEWAGE AND WASTE WATER}

The present invention relates to a method for the simultaneous removal of nitrogen and phosphorus from sewage or wastewater. More specifically, the present invention relates to a method for simultaneously removing nitrogen and phosphorus from sewage or wastewater using a reaction tank including a PFR separation tank, a primary precipitation tank, a nitrification tank, a quasi-anaerobic buffer anoxic tank, an anoxic tank, a stabilization tank, and a final precipitation tank.

Conventionally, a method for treating wastewater using a reaction tank consisting of a contact tank, a primary precipitation tank, a phosphorus discharge tank, a nitrification tank, a denitrification tank, a phosphorus discharge tank, a phosphorus absorption tank, and a final precipitation tank has been known. For example, Korean Patent Laid-Open Publication No. 2000-0040351 (see FIG. 1) discloses that waste water is introduced from a contact tank under aerobic conditions to attach organic matter to microorganisms, thereby attaching organic matter to the microorganisms, and then, all of the resulting mixed solution is firstly applied. It is sent to the settling tank to separate the microbial sludge and the supernatant water, and then a part of the microbial sludge is discarded, and the rest is sent to the phosphorus discharge tank under the completely closed anaerobic condition. After oxidizing ammonia nitrogen to nitrate nitrogen, the microbial sludge and the supernatant separated into the denitrification tank are mixed, and the supernatant is mixed with the whole mixed liquid introduced from the phosphate discharge tank and the microbial sludge returned from the final settling tank. Nitrogen-containing nitrogen is reduced, degassed into the atmosphere with nitrogen gas, and then all of the mixed solution is introduced into a phosphorus absorption tank. After absorbing into the organism, the mixed liquid is sent to the final settling tank, and then separated into microbial sludge and supernatant water, and then a part of the microbial sludge is returned to the contact tank, and a part is returned to the denitrification tank, and the rest is discarded and the symbol water is discharged. It describes a method for treating wastewater using microbial contact. In addition, a method for omitting the nitric oxide precipitation tank by providing a membrane instead of a carrier in the nitrification tank and a method for omitting the final precipitation tank by installing a membrane in the phosphorus absorption tank are also described.

In addition, Korean Patent No. 022795 describes a method for simultaneously treating nitrogen and phosphorus using a microorganism using a reaction tank consisting of a first aerobic tank, a first settling tank, a second aerobic tank, an anaerobic tank, an anaerobic tank, and a third aerobic tank. Other biosorption methods and methods by flocculant injection are described, for example, in Journal of energy, Heat and mass transfer, Vol. 18, 267-274, 1996, "New processes for the removal of carbon and ammonia from wastewater"; Water research Vol. 17, No. 11, pp. 1591-1594, 1983, "Sorption of organic by selenastrum capricornutum"; JWPCF, Vol. 59, NO.4, pp. 191-198, 1987, "Removal of hazardous organic pollutants by biomass adsorption"; 1996 Yonkang Foundation Research Report, 4th, Environmental Research Papers, pp. 453-461, 1997, Study on Improvement of Existing Sewage Treatment Process for Simultaneous Removal of Organic Nitrogen Phosphorus.

However, conventional biosorption methods have the following problems.

(1) The bioadsorption tank has a slow sludge settling rate in the settling tank because the microorganism adsorbs organic material within a short residence time (HRT) (20 to 60 minutes) under aerobic conditions, and the sludge leaks out to the settler ware or requires an artificial sludge drawing line. It was.

(2) When the bioadsorption tank is operated in the form of a CSTR in aerobic conditions, the biosorption efficiency is low due to sludge bulging and flocculation due to aerobic oxidation, and the discharge of suspended solids (SS) As a result, an increase in the load of suspended solids (SS) in the nitrification tank causes nitrification inhibition of the nitric oxide and at the same time, a draw line for discarding nitrifying microorganisms is added, thereby generating high sludge.

(3) Denitrification in a biosorption tank operated under aerobic conditions because the sludge returned from the final settling tank contains about ₃ to 4 mg / l of NO x -N (NO ₃ -N + NO ₂ -N) concentrations. Sludge flotation is expected due to denitrification in the primary sedimentation tank, and at the same time, when the sludge transported from the primary sedimentation tank enters the anaerobic tank, the electron acceptor NO ₃ -N inhibits phosphorus release.

(4) If the role of the biosorption tank is adsorption of organic substances using microorganisms, physicochemical adsorption, ie, isothermal adsorption reaction, is mainly performed rather than biochemical biosorption, and the adsorption of particulate organic materials is more important than adsorption of dissolved organic materials. Should be. Therefore, it is difficult to simultaneously proceed with the denitrification electron donor action and the adsorption of microorganisms of Readily biodegradable organic materials (RBDCOD) which are prone to biodegradation under aerobic conditions.

(5) Phosphorus release tanks configured to release phosphorus under anaerobic conditions undergo incomplete phosphorus release due to residual nitrogen nitrate (NOx-N) in bioadsorption tanks operated in aerobic tanks, and at the same time, solubilized organic nitrogen. Ammonia nitrogen (NH ₄ -N) flows into the subsequent reactor.

(6) The existing method uses nitric oxide as a floating-phase process to oxidize ammonia nitrogen to nitrate nitrogen, which is very difficult to maintain due to high power costs and excessive complexity of the facility itself. In addition, when industrial wastewater and livestock wastewater, such as hardly decomposable organic compounds, are introduced and introduced, it causes an impact load on the nitrification tank to which the adherent microbial carrier is injected, and nitrification reaction is easily suppressed, so that the oxygen diffusion coefficient must be maintained by supplying high concentration oxygen. do. In addition, the sludge generation process has to be added because the sludge generation rate is higher than the attachment process sludge (Yt: 0.45 ~ 0.75) and the sludge treatment process has to be added. 750 ml / l).

(7) The attached sludge system has a negative problem of increasing the phosphorus concentration in the effluent due to the longer microbial retention time (SRT) than the suspended sludge system and the easy removal of temporary inactive microorganisms.

The present invention operates a biosorption tank in a plug flow reactor separator (PFR separation tank) of anoxic conditions, not aerobic conditions, in order to solve the problems of the method using the biosorption as described above, the rotating disc in the nitrification tank (RID: rotating immersion disks) and the stabilization tank that absorbs phosphorus are installed by microbial carrier (HBC) or rotating disc (RID) to reduce the residence time in each reactor and ultimately minimize the power required It is an object of the present invention to provide a method for simultaneously removing nitrogen and phosphorus from sewage water.

In addition, the sludge returned from the final settling tank is returned to the anaerobic buffered anoxic tank and the nitrification tank without returning the sludge to the anoxic tank to remove nitrate nitrogen in the conveying sludge from the semi-anaerobic buffered anoxic tank, and remains in the nitrate tank effluent with the rotating disc (RID) installed. The return line is configured to exhaust oxygen.

In addition, a quasi-anaerobic buffered anaerobic tank is installed to allow denitrification and phosphorus release in a locally anaerobic state formed by a high concentration of sludge layer in an open state without being completely sealed like anaerobic conditions.

In addition, the stabilization tank in which the microbial carrier is installed is provided with a pure oxygen production facility to increase the oxygen supply rate to reduce the residence time in the stabilization tank, while increasing the reaction rate and to minimize the amount of sludge generated. do.

In addition, an object of the present invention is to provide a method of shortening the residence time by adding microbial flocculant at the front of the PFR separation tank or the final precipitation tank to promote precipitation in the primary precipitation tank and the final precipitation tank.

1 is a process flow chart used in a conventional method for treating wastewater using microbial contact (Korean Patent Laid-Open Publication No. 2000-0040351),

2 is a process flow diagram using a nitrification tank and a floating bed stabilization tank in which a rotating disc (RID) of the present invention is installed;

3 is a process flow diagram using a nitriding tank equipped with a rotating disc (RID) of the present invention and a stabilization tank equipped with a microbial carrier (HBC),

Figure 4 is a process flow diagram using the nitrification tank and the stabilization tank in which the rotating disc (RID) of the present invention is installed.

* Explanation of symbols for main parts of the drawings

2: PFR separation tank 4: primary settling tank

6: nitrification tank 8: quasi-anaerobic buffer anoxic tank

10: anoxic tank 12: stabilization tank

14: final sedimentation tank

16: Sludge line transferred from primary settling tank to semi-anaerobic buffered anaerobic tank

18: conveying sludge line conveyed from final settling tank to nitrification tank

20: Return sludge line returned from the final settling tank to the quasi-anaerobic buffer anoxic tank

22: Return sludge line returned from final settling tank to PFR separation tank

Simultaneous removal of nitrogen and phosphorus from the sewage or wastewater according to the present invention is carried out by returning the sludge returned from the sewage / wastewater and the final settling tank 22 to a plug flow reactor separator (PFR separator) under anoxic conditions (2). Incorporating and admixing the bio-adsorbed); Sending all of the mixed liquid stayed in the plug flow reactor type separation tank for a predetermined time to the primary settling tank (4) for solid-liquid separation; The conveying sludge 18 conveyed from the supernatant water and the final sedimentation tank 14 among the solid-liquid separated liquid mixture in the primary sedimentation tank 4 is transported and mixed to the nitrification tank 6 in which the rotating disc RID is installed to mix ammonia nitrogen. Oxidizing with nitrate nitrogen; The precipitated sludge 16 precipitated in the mixed liquid separated from the solid-liquid separated liquid in the primary settling tank 4 and the conveying sludge 20 conveyed from the final settling tank are transported and mixed to the quasi-anaerobic buffer anoxic tank 8 to remain in the conveyed sludge. Acidic nitrogen (NOx-N) to denitrify and release phosphorus out of the microorganism; Transporting the nitrified symbolic water in the nitrification tank (6) to the anoxic tank (10) and mixing it with the denitrified mixed liquid introduced through the space communicated from the semi-anaerobic buffer anoxic tank (8) to completely denitrify; Transferring the completely denitrified mixture to the stabilization tank 12 to completely oxidize residual organic matter and ammonia nitrogen and to absorb phosphorus into the microorganism; All of the mixed solution completely oxidized in the stabilization tank 12 and phosphorus absorbed in the microorganism body is transferred to the final settling tank 14 to be separated into supernatant water and microbial sludge, and the supernatant water is discharged to the outside and the microbial sludge The part is characterized in that it comprises the step (22, 18, 16) of returning to the plug flow reactor type separation tank, nitrification tank and buffered anoxic tank under the anoxic conditions and discarding the rest (see Fig. 2).

Each reactor used in the method of the present invention is basically a plug flow reactor (PFR: one-way extrusion reactor).

Each reaction tank used in the method of the present invention is a PFR separation tank (2), a primary precipitation tank (4), a nitrification tank (6) equipped with a g-rotating disc, a quasi-anaerobic moderate anoxic tank (8), an oxygen-free tank (10), stabilization tank ( 12) and the final settling tank 14. The method of the present invention will be described with reference to the reaction occurring in the reactor as follows.

(1) biosorption in an anoxic PFR separation tank (2)

In this PFR separation tank 2, the return sludge 22 conveyed from the sewage and wastewater and the final sedimentation tank is introduced and mixed to be biosorbed under anoxic conditions.

This separation tank is anoxic and operates with plug flow, so sludge bulking and flocculation are low. In this separation tank (2), an underwater mixer, a line mixer, or an agitator is used to mix the sludge in the reaction tank, and when the trap is installed outside the primary sedimentation tank or a conduit-type PFR separation tank, the agitator may be omitted. have.

Since the PFR separation tank 2 is operated under anoxic conditions as described above, the complete denitrification of nitrate nitrogen (NO ₃ -N) remaining in the sludge returned from the final settling tank within a short time, for example, a residence time of 30 minutes. Let's do it. This will prevent sludge flotation in the primary settling tank. It is preferable that the quantity of the conveying sludge 22 conveyed from a final precipitation tank is 20-25 volume% with respect to raw water flow volume.

The microbial concentration (MLSS) in the PFR separation tank (2) is maintained at about 2,000 to 2500 mg / l and dissolved organic matter is adsorbed to the microorganism (MLSS). Adsorption in this case can be predicted by, for example, Freundlich isotherm theory.

In addition to the denitrification reaction, the PFR separation tank 2 mixes particulate organic materials in raw water with the final settling tank return sludge, adsorbs them to microorganisms, and ultimately separates carbon and nitrogen. To be in a state. Raw water with carbon and nitrogen separated keeps the C / N ratio at 1 ~ 2 low in the nitrification tank and predominates the nitric oxide to reduce nitrification rate.

In addition, using a suitable mixing means, for example, a line mixer at the front of the PFR separation tank 2, flocculant alum (Al ³⁺ ) or iron salt (Fe ³⁺ ) is dissolved in raw water. It can be injected in a 1: 1 ratio to soluble PO ₄ ^3- -P) concentration. This improves the adsorption rate of organic substances, improves the adsorption and floc formation of microorganisms, and removes dissolved phosphorus to reduce the load of phosphorus so that stable precipitation can occur in the primary settling tank (4).

(2) solid-liquid separation in the primary settling tank

In the primary sedimentation tank (4), the liquid mixture separated from the PFR separation tank (2) under anoxic conditions is solid-liquid separated, and the total amount of the precipitated sludge is transferred to the quasi-anaerobic buffer anoxic tank (8). It is sent to the nitrification tank (6) installed so that the nitrification reaction proceeds.

The hydraulic residence time (HRT) in the sedimentation tank 4 is 2.0 to 2.5 hours, and the surface area load is 25 to 30 m ³ / m ² days.

In the conventional biosorption tank using an advanced biosorption tank, the biosorption tank 2 is operated under aerobic conditions, so the sludge settling rate is slowed by sludge bulking, and the sludge blanket layer rises to 2/3 of the settling tank. In many cases, drawing sludge or maintaining the ratio of precipitated sludge to be transferred to the anaerobic tank has a high amount of ammonia nitrogen to reduce the nitrogen removal efficiency.

(3) nitrifying in a nitrification tank (6) having a rotating disc (RID) installed

The nitrification tank 6 is conveyed and mixed with the supernatant water and the return sludge 18 conveyed from the final settling tank in the mixed liquor separated from the solid solution in the primary settling tank 4. In this nitrification tank 6, ammonia nitrogen is oxidized to nitrate nitrogen by nitrifying bacteria.

Since the symbol water conveyed from the primary sedimentation tank 4 is of low C / N ratio conditions, for example, 1 to 2, such as Nitrobacter or Nitrosomonas attached to the RID, More than 99% nitrification in a short time by the nitrification bacteria. The time spent for nitrification is preferably 1 to 2.5 hours.

The rotational disc (RID) provided in the nitrification tank 6 has a very low sludge generation rate of heterotrophic organisms since the retention time of microorganisms is extended (Yt <0.0488). In particular, unlike the conventional method of injecting air into the nitrification tank using a blower, by using a rotary nitriding disc (RID), the power cost can be reduced by 1/4 to 1/6, and the nitrification tank can be installed underground. Therefore, it takes less land.

The microorganisms present in the effluent of the nitrification rotary disk (RID) of the nitrification tank 6 are stalked ciliates and rotifers, which are mostly observed in clean water, and pass through the anoxic tank 10 and the stabilization tank 12, and the final precipitation tank 14 (SS) outflow is not a problem because it is separated from. Microorganisms observed in the nitrate 6 effluent include Pseudomonas, Bacillus, Nocardia, Streptomyces, and the like.

The amount of sludge 18 returned from the final settling tank is preferably about 5% by weight relative to the raw water flow rate and is intermittently returned to the nitrification tank or to exhaust the dissolved oxygen contained in the outflow symbol water of the winter anaerobic tank 10. .

(4) denitrification of nitrate nitrogen in the quasi-anaerobic buffered anaerobic tank (8) and release of phosphorus out of the microorganism;

In the quasi-anaerobic buffered anoxic tank 8, the precipitated sludge 16 precipitated in the mixed liquid separated from the solid-liquid separated liquid in the primary precipitation tank 4 and the return sludge 20 conveyed from the final settling tank are transferred and mixed to obtain a high concentration of microorganisms (7,000- Under the condition of 10,000 mg / L), phosphorus is released to the outside of the microorganism within a short time after denitrification of nitrate nitrogen (NOx-N) remaining in the return sludge. The amount of sludge 16 conveyed from the primary settling tank is preferably about 20 to 25% by volume based on the raw water flow rate, and the sludge 20 conveyed from the final settling tank is about 5 to 10% by volume relative to the raw water flow rate.

The quasi-anaerobic anoxic tank (8) is not operated in a completely closed state like the anoxic tank (10), but is operated in an open type (open) and the high concentration of sludge is agitated, so that it can be discharged under semi-anaerobic conditions. The quasi-anaerobic buffer anoxic tank (8) and the anaerobic tank (10) is connected to each other can be used as an anaerobic tank depending on the water quality conditions and operating conditions. In addition, as shown in Table 1, the concentration of domestic raw water quality phosphorus is less than 3mg / l, it is inefficient to maintain the phosphorus discharge tank in anaerobic conditions for phosphorus release.

The semi-anaerobic buffer anoxic tank has a hydraulic retention time (HRT) of 30 minutes, microbial concentration (MLSS) of 7,000 to 10,000 mg / l, pH is preferably maintained at 6.7 to 7.1 mg / l, in this case the microbial concentration is Since it is maintained at 2.5 times higher than the existing anaerobic reactor, the concentration of phosphorus phosphate (PO ₄ ^3- -P) is 3.5-5.6 mg / l even under the open state, more than 3 times higher than 0.5-1.5 mg / l of the primary sedimentation effluent. Phosphorous release can be induced.

The effluent water of the semi-anaerobic buffered anoxic tank (8) has a chemical oxygen demand (SCODcr) concentration of 65 to 95 mg / l, and nitrate nitrogen (NO ₃ ^-- N) of <0,2 mg / l, which is preferably an anoxic tank. If spilled at (10), residual organic material can lead to a high SDNR (spedific denitrification rate) from 0.15 to 0.35 gNO ₃ ^-- N / gVSS days (> 15 ° C) .

(5) complete denitrification in the anoxic tank (10)

In this oxygen-free tank 10, the supernatant water and the sludge mixture in the quasi-anaerobic buffered anoxic tank 8 are transferred and mixed from the nitrification tank 6 in which the rotary disc for nitrification (RID) is installed. Denitrification by reduction to N ₂ .

The residence time in the anaerobic tank is 2.0 to 2.5 hours, the microorganism concentration (MLSS) is 3,000 to 4,500 mg / l, the DO is <0.2 mg / l, the pH is 7., 1 to 7.5, and the redox potential (ORP) is It is desirable to remain below -100 mV.

The bacteria found in the anaerobic tank 10 include Bacillus Denitrificans, Micrococcus Denitrificans, Pseudomonas Stutzeni, Achromobacter, and the like. .

(6) absorbing phosphorus into the microorganism in the stabilization tank 12

The stabilization tank 12 is a reaction tank for operating the sludge mixed liquid transferred from the anoxic tank 10 under aerobic conditions. In the stabilization tank 12, the organic substance and ammonia nitrogen remaining after the denitrification reaction is completed in the anoxic tank 10 are oxidized and phosphorus released from the semi-anaerobic buffered anoxic tank 8 and the anoxic tank 10 is absorbed by the microorganism. do. Phosphorus-absorbing microorganisms are also called phosphorus accumulating organisms (PAOs).

The stabilization tank 12 can be provided with a microbial carrier (HBC) (see Fig. 3). The installation of a microbial carrier can reduce the hydraulic retention time (HRT) of an existing suspended bed system by half and can be reduced by up to 20 minutes.

When the microorganism carrier is installed in the stabilization tank 12 as described above, a pressure swing adsorption (PSA) pure oxygen production facility may be additionally installed. When the PSA pure oxygen production facility is installed, the hydraulic residence time (HRT) can be drastically reduced since an oxygen transfer efficiency can be obtained higher than that of a conventional blower. In addition, it is possible to maintain a high concentration of microorganisms can be effectively applied to difficult-degradable wastewater and to suppress the odor volatilization by completely sealing the reaction tank.

In addition, the stabilization tank 12 may be provided with a rotating disc (RID) (see Figure 4). The installation of a rotating disc can reduce the hydraulic residence time (HRT) of an existing suspended bed system in half and can be reduced by up to 20 minutes.

(7) discharging the final treated water by solid-liquid separation in the final settling tank (14)

In the final sedimentation tank 14, all of the mixed liquid which is completely oxidized in the stabilization tank 12 and phosphorus absorbed into the microorganism body is transferred and separated into supernatant water and microbial sludge, and the supernatant water is discharged to the outside and the microorganism is discharged. Part of the sludge is returned (22, 18, 20) to the PFR separation tank, the nitrification tank, and the buffer anoxic tank under anoxic conditions, and the rest is discharged. It is preferable that the conveyance costs returned to the PFR separation tank, the nitrification tank, and the buffer anoxic tank (22, 18, 20) are 20-25% by volume, 5-10% by volume, and about 5% by volume, respectively. The hydraulic retention time (HRT) in the final settling bath is preferably about 2.5 to about 3.5 hours.

In addition, the flocculant alum (Al ³⁺ ) or iron salt (Fe ³⁺ ) was dissolved in raw water by using a line mixer in front of the final settling tank 14 (soluble PO ₄ ^3- -P). It can be injected 1: 1 in concentration. This increases the adsorption rate of the organic material to improve the adsorption and floc formation of the microorganisms and to remove the dissolved phosphorus to reduce the load of phosphorus so that the stable precipitation in the final precipitation tank 14 can occur.

Example

Example 1

[Feature Analysis of Sewage and Wastewater Sources in Korea]

As a result of analyzing the inflow water quality of about 154 sewage treatment plants in Korea from October 1, 1999 to March 31, 2000, the influent C / N ratio was 2.67 ~ 3.24 and the C / P ratio was 34.8 ~ 40.1.

Table 1. Characteristics of Raw Water from Sewage Treatment Plant in Korea

Analysis period Biological Oxygen Demand (BOD) (mg / l) Chemical Oxygen Demand (COD _MN ) (mg / l) Suspended matter (SS) (mg / l) Total Nitrogen (TN) (mg / l) Total phosphorus (TP) (mg / l) 1999.10.1-12.31 93.9 55.1 126.1 35.1 2.7 2000.1.1-3.31 116.2 65.3 122.8 35.7 2.9

Based on the raw water quality as shown in Table 1, the nitrogen concentration characteristics of raw water irradiated at T sewage treatment plant are as follows.

Total nitrogen (TN): 35.5-40.0 mg / l

Ammonia nitrogen (NH ₄ -N): 18.5 to 25.4 mg / l

Organic Nitrogen: 13-15.2 mg / l

Nitrate Nitrogen (NOx-N): 1.6 to 4 mg / l

Therefore, the nitrogen concentration contained in particulate organic matter in raw water was found to be about 13 mg / l or more.

[Application Result of PFR Separation Tank in Anaerobic Condition]

When the raw water flowing into the T sewage treatment plant is operated in a PFR separation tank (2) in anoxic conditions (agitated at 25 rpm) and in a PFR separation tank in an aerobic condition (mounting of an engine, Q = 2 l air / min). The results were compared.

The operating conditions were as follows.

Reactor and volume: 5l acrylic reactor, temperature = 20 ° C, raw water to sludge mixing ratio = 1: 0.3, pH = 7.2, aerobic dissolved oxygen concentration (DO) = 0.5-1.0 mg / l, reaction time = 30 minutes After 30 minutes of settling, the symbol number was analyzed. Total CODcr concentration of raw water = 150 mg / l and raw nitrogen (TN) concentration = 35 mg / l. The analysis results are shown in Table 2.

Table 2. Comparison of the Results of Operation of Anaerobic and Aerobic Conditions in PFR Separators

(Inflow: before sewage treatment at T sewage treatment plant)

division Sludge Volume (SV30) (ml / l) Chemical Oxygen Demand (CODcr) (mg / l) Organic Nitrogen (org-N) (mg / l) Nitrate Nitrogen (NO ₃ -N) (mg / l) Total Floating Substance (TSS) (mg / l) pH Anaerobic condition (25 rpm stirring) 450 55 1.5 0.1 45 7.5 Aerobic condition (Q = 2l / min) 850 80 3.3 3.8 76 6.9

As can be seen in Table 2, organic nitrogen contained in the particulate organic material is mixed with the final settling tank return sludge 22 in an oxygen-free PFR separation tank (2) and adsorbed with the particulate organic material, and then solid-liquid separation in the primary precipitation tank. As a result, more than 95% of organic nitrogen was removed and only soluble ammonia was introduced into the nitrification tank. In addition, it was found that the concentration of nitrate nitrogen (NO ₃ -N) in the primary sedimentation tank effluent was mostly denitrified to 0.2 mg / l.

Example 2

In this embodiment, the operation results of the nitrification tank 6 in which the nitric oxidation rotary disc (RID) is installed were analyzed.

The operating conditions were as follows.

The material for the nitriding rotation disc (RID) was polypropylene, the disk thickness was 2 mm, the disk diameter was 2 m, and the disk spacing was 10 to 15 mm. Operating temperature is 20-22 ° C, pH is 7.0-7.2, dissolved oxygen concentration (DO) is 4-6 mg / l, hydraulic retention time (HRT) is 1.5-2 hours, disk surface area nitrogen load is 2-6 gN / m ^It was ² days.

As a result of the operation, the nitrification efficiency was 99%, and the ammonia nitrogen (NH4-N) <0.2mg / l and the nitrogen nitrate (NOx-N) in the supernatant effluent at the final stage of the nitrification tank before the final settling tank return sludge was 20-23 mg / l, soluble Kjeldahl nitrogen (TKN) <1.0 mg / l. Total chemical oxygen demand (TCODcr) <74 mg / l, suspended solids chemical oxygen demand (SCODcr) <25 mg / l, suspended solids amount (SS) <68 mg / l.

Example 3

This embodiment relates to the actual operation results of the quasi-anaerobic buffered anaerobic tank 8.

The retention time (HRT) was maintained for 30 minutes, the microbial concentration was 7,000 mg / l to 10,000 mg / l, and the pH was 6.7 to 7.1 mg / l. It was operated open and stirred.

Phosphorous phosphorus (PO ₄ ^3- -P) concentration in the semi-anaerobic buffered anaerobic effluent was 3.5 to 5.6 mg / l, which is three times the concentration of 0.5 to 1.5 mg / l of the primary leachate effluent. I could see that there was. The chemical oxygen demand (SCODcr) concentration was 65 to 95 mg / l, and the nitrate nitrogen (NO ₃ -N) was <0.2 mg / l.

Therefore, if the effluent from the above-mentioned anaerobic buffered anoxic tank flows out into the anoxic tank, the denitrification rate (SDNR) in the anoxic tank can be induced as high as 0.15 to 0.35 gNO ₃ -N / gVSS days (> 15 ° C). Could.

Example 4

This embodiment relates to the actual operation results of the anaerobic tank 10.

Retention time is 2.0 to 2.5 hours, microorganism concentration (MLSS) is 3,000 to 4,500 mg / l, oxidation-reduction potential (ORP: oxidation-reduction potential) is -70 mV to -250 mV, dissolved oxygen is 0.2 mg / l, pH is 7.1 Was maintained at -7.5. The result of analyzing the symbolic water by sanitizing the final anaerobic runoff for 30 minutes is as follows.

pH is 7.1-7.5, dissolved oxygen concentration (DO) is 0mg / l, chemical oxygen demand (CODcr) is 30-45mg / l, biological oxygen demand (BOD) is 25-35mg / l, soluble total nitrogen (TN) is 5-7 mg / l, nitrate nitrogen (NOx-N) 3-4 mg / l, soluble ammonia nitrogen (NH ₄ -N) 2-3 mg / l, sludge volume (SV30) 420-510 ml / l, The denitrification rate (SDNR) was 0.15 to 0.35 gNO-N / gVSS day (> 15 ° C), and the phosphoric acid phosphorus (PO ₄ ^3- -P) was 2.5 to 4.5 mg / l.

Example 5

This embodiment relates to the actual operation results of the stabilization tank in which the floating phase stabilization tank 12 is installed.

The microbial concentration (MLSS) was 2500-4000 mg / l. The results are shown in Table 3.

Table 3. Operation result of floating phase stabilization tank

division Chemical Oxygen Demand (CODcr) (mg / l) Biological Oxygen Requirements (BOD) (mg / l) Ammonia Nitrogen (NH ₄ -N) (mg / l) Sludge Volume (SV30) (ml / ml) Phosphoric Acid Phosphorus (PO ₄ ^3- -P) (mg / l) Residence time (HRT) (hr) Floating phase process <30 <12 3.5 to 5.5 450/1000 0.2 to 0.5 One

Example 6

This embodiment relates to the result of actually operating a process in which the microbial carrier (HBC) and the rotating disc (RID) are installed in the stabilization tank 12. The microbial carrier (HBC) installed in the stabilization tank was filled with 6.8% of the volume. The suspended microorganism concentration (MLSS) was 2,500 to 4,000 mg / L, and the total amount of the microorganisms attached to the carrier was removed and converted to the suspended microbial concentration. Maintained at 8,000 mg / l, stabilization tank residence time can be shortened by up to 1/3 than the floating bed process. The rotating disk (RID) installed in the stabilization tank 12 was rotated at 3rpm by the rotating motor with a diameter of 2m, thickness of 2mm and disk spacing of 10mm of polypropylene, and the disk surface load was 20g BOD / m ² days, 2 It was designed as -6 gN / m ² days. The stabilization tank equipped with the rotating disc (RID) was able to nitrate the residual ammonia nitrogen by 99% as a result of operation, and it was used instead of the blower, so there was no noise, vibration, and odorous acid, and the required power could be reduced by 1/3 compared with the existing blower. .

Table 4. Operation result of stabilization tank equipped with HBC and RID.

division Chemical Oxygen Demand (CODcr) (mg / l) Biological Oxygen Demand (BOD) (mg / l) Ammonia nitrogen (NH ₄ -N) (mg / l) Sludge Volume (SV30) (ml / ml) Phosphoric Acid Phosphorus (PO ₄ ^3- -P) (mg / l) Residence time (HRT) (hr) HBC <27 <9 1.5 to 2.0 350/1000 0.3 to 0.6 0.33 RID <35 <11 0.3 to 0.6 150/1000 0.7 to 1.1 0.50

Example 7

Pilot plant operation using the simultaneous removal method of nitrogen and phosphorus using a nitric oxide tank equipped with a rotary disk (RID) of the present invention is shown in Table 4.

Table 4. Pilot Plant Operation Results of Simultaneous Removal of Nitrogen and Phosphorus Using Nitrification Tank with Rotating Disc (RID)

division Biological Oxygen Demand (BOD) (mg / l) Chemical Oxygen Demand (CODcr) (mg / l) Suspended matter (SS) (mg / l) Total Nitrogen (TN) (mg / l) Total phosphorus (TP) (mg / l) Capacity (l / day) A 9 28 14 8.0 0.7 100 B 13 32 17 10 1.0 100 C 15 35 18 12 1.2 100

A: When using a nitrification tank equipped with a rotating disk (RID) and a stabilization tank equipped with a microorganism carrier (HBC).

B: When using nitriding tank equipped with rotating disc (RID) and stabilization tank of floating process.

C: In case of using nitrification tank with RID and stabilization tank with RID.

As a result of applying the method of the present invention in a 100 m ³ / day pilot plant, the unit reaction tank residence time (HRT) was PFR separation tank: 0.5 hour, primary precipitation tank: 2.0 hours, nitrification tank: 2.0-2.5 hours, semi-anaerobic buffered anoxic tank : 0.4 hour, stabilization tank: 0.5 hour, final precipitation tank: 2.5 hours.

Here, the total residence time (HRT) of the biological reaction tank excluding the precipitation tank is 5.9 hours, and when the nitrification and anoxic tanks are shortened up to 1 hour, biological nitrogen phosphorus can be removed within 4.9 hours.

According to the method of the present invention, the residence time in the activated sludge bioreactor of the existing sewage treatment plant can be renovated to be within 6 hours. It is also possible to remove nitrogen and phosphorus without supplying an external carbon source. By installing the rotational disc for nitrification (RID), the power cost can be reduced to 1/4 to 1/6 of the existing power cost, and complete nitrogen removal is possible.

According to the present invention, it is possible to prevent the sludge floating phenomenon in the primary settling tank by operating the PFR separation tank in anoxic conditions.

According to the present invention, by providing a rotary disk (RID) in the nitrification tank, it is possible to shorten the residence time of the sewage and waste water in the nitrification tank. In addition, the power costs can be reduced to 1/4 to 1/6 of the existing power costs, and complete nitrogen removal is possible.

According to the present invention, by installing a rotating disk (RID) in the nitrification tank and at the same time by installing a microbial carrier (HBC) or a rotating disk (RID) in the stabilization tank, as well as the residence time in the nitrification tank of the waste water, The residence time can be shortened.

According to the present invention, in the case of installing a rotating disk (RID) in the stabilization tank by installing pure oxygen production facilities in these reaction tanks to increase the oxygen supply rate to the microorganisms to further shorten the residence time in the nitrification tank or stabilization tank Can be.

According to the invention, PFR-separating tank or the final sedimentation tank shear coagulant alum (Al ³⁺⁾ or iron (Fe ³⁺⁾ in the first relative to the soluble phosphate sex (soluble PO ₄ ^3- -P) concentration in the raw water: 1 Injection can promote sludge formation and shorten the residence time, as well as prevent excessive phosphorus loading.

In addition, according to the present invention it is possible to minimize the site required for the installation of the sewage treatment plant because the treatment speed is fast and the amount of sludge generated by the synergy of the above effects.

Claims (6)

Introducing and mixing the return sludge returned from the sewage / wastewater and the final sedimentation tank into a plug flow reactor separator (PFR separator) under anoxic conditions and bioadsorption; Sending all of the mixed liquid stayed in the plug flow reactor type separation tank for a predetermined time to the primary settling tank for solid-liquid separation; The return sludge returned from the supernatant water and the final settling tank in the solid-liquid separated liquid in the primary sedimentation tank is transported and mixed to a nitrification tank equipped with high efficiency rotary immersion disks (RID) to oxidize ammonia nitrogen to nitrate nitrogen. Making a step; A step of denitrifying nitrogen nitrate (NOx-N) remaining in the conveying sludge by transferring and mixing the precipitated sludge precipitated in the solid-liquid separated liquid mixture in the primary precipitation tank and the final sludge returned to the semi-anaerobic buffer anoxic tank; Transporting the nitrified symbolic water from the nitrification tank to the anoxic tank and mixing with the denitrified mixed solution introduced through the space communicated from the semi-anaerobic buffered anoxic tank to completely denitrify; Transferring the completely denitrified mixture to a stabilization tank to completely oxidize residual organic matter and ammonia nitrogen and to absorb phosphorus into the body of the microorganism; Transfer all of the mixed solution completely oxidized in the stabilization tank and phosphorus absorbed in the microorganism body to the final settling tank, separated into supernatant water and microbial sludge, all the supernatant water is discharged to the outside and part of the microbial sludge is the anoxic condition A method of simultaneously removing nitrogen and phosphorus from sewage or wastewater comprising the steps of returning to a plug flow reactor type separation tank, a nitrification tank and a buffered anoxic tank and discarding the rest. The method of claim 1, wherein the stabilization tank is a microbial carrier (HBC) is installed, characterized in that the simultaneous removal of nitrogen and phosphorus in sewage or waste water. 3. The method for simultaneously removing nitrogen and phosphorus from sewage or wastewater according to claim 2, wherein a PSA pure oxygen production facility is installed in a stabilization tank in which the microbial carrier (HBC) is installed. The method of claim 1, wherein the stabilization tank is a rotary disk (RID) is installed, characterized in that the simultaneous removal of nitrogen and phosphorus in the sewage or wastewater. The method of claim 1, wherein the flocculant alum (Al ³⁺ ) or iron salt (Fe ³⁺ ) is dissolved in raw water using a line mixer in front of the plug-flow reactor type separation tank or the final settling tank under anoxic conditions. Simultaneous removal of nitrogen and phosphorus from sewage or wastewater, characterized in that 1: 1 injection to soluble PO ₄ ^3- -P concentration. The method according to any one of claims 1 to 5, wherein the conveying sludge conveyed to the PFR nitrification tank is 20 to 25% by volume of the raw water, the conveying sludge conveyed to the nitrification tank is 5 to 10% by volume of the raw water, Simultaneous removal of nitrogen and phosphorus in sewage or wastewater, characterized in that the return sludge conveyed to the quasi-anaerobic buffer anoxic tank is 5 to 10% by volume of raw water.