KR20090121860A - Apparatus for biological treatment of wastewater including sequencing batch reactor linked with air-flotation process, and method for wastewater treatment using the same - Google Patents

Abstract

PURPOSE: A biological sewage processing device including a continuous reaction bath and a sewage processing method using the same are provided to increase processing efficiency of biological nitrogen and phosphorous. CONSTITUTION: A biological sewage processing device including a continuous reaction bath includes a reactor bath(1), a mixer(2), a diffuser(3), a sewage inflow part(4), a control part(6), and a reaction bath water level sensor(7). The mixer is equipped inside the reaction bath. The diffuser is formed on the bottom of the reaction bath. The sewage inflow part is connected to a side of ht reaction bath. A treated water drawing part is connected to the bottom of the reaction bath.

Description

Apparatus for biological treatment of wastewater including sequencing batch reactor linked with air-flotation process, and method for wastewater treatment using the same

The present invention relates to a device and method for biologically advanced sewage treatment by combining a technique for generating fine bubbles and flotation of sludge and a continuous batch sewage treatment apparatus, and more particularly, in a continuous batch reaction process. By selectively adjusting the pressure of the air flowing into the diffuser, it not only supplies oxygen required for nitrification and phosphorus intake reaction, but also generates microbubbles to separate the sludge from the sewage from which the reaction is completed, thereby economically and efficiently discharging sewage. An apparatus and method for advanced processing.

At a time when global environmental concerns are high, human desire for a safe and clean water environment continues to grow. The function of sewage treatment, which previously targeted only organic matter removal, has been improved by applying advanced treatment technologies including nitrogen and phosphorus removal.

Advanced treatment technology can be largely divided into physical and chemical treatments and biological treatments, and complex treatments using both methods simultaneously. Physical and chemical treatments include flocculation, sedimentation, separation, adsorption, ion exchange, and oxidation. Biological treatments include aerobic treatment, anaerobic treatment, a combination of aerobic treatment and anaerobic treatment. Combined treatment is a water treatment technology consisting of various unit processes of physicochemical and biological treatment steps.

In general, biological removal is the most preferred method among various advanced treatment methods for removing nitrogen and phosphorus. This is because ① processing efficiency is high, ② process stability and reliability are high, ③ process operation is relatively easy, and ④ processing cost is economical. Many biological advanced treatment processes utilize the form of activated sludge process, but use a mixture of anaerobic, anaerobic and aerobic conditions or reactors to remove nitrogen and phosphorus. There are about 50 modifications of the advanced biological treatment process developed in Korea. The most basic processes used to remove nitrogen and phosphorus include A2 / O process, 5-step Badenpho process, UCT process, VIP process and continuous batch process. Reaction process (SBR) and the like.

Among them, the continuous batch reaction process is a fill-and-draw activated sludge treatment process. The process converts the spatial concept of activated sludge process into a temporal concept and does not require separate anaerobic, anoxic and aeration tanks as well as internal transfer lines and pumps for sludge and nitrogen removal, and a final settling tank. In one reactor, the sewage is advanced through five stages: ① Fill ② React ③ Settle ④ Draw ⑤ Idle.

The continuous batch reaction process can cope with load fluctuations or impact loads because ① the sewage inflow process acts as an equalizer. ② All the processes required for advanced treatment in a single reactor can be minimized by changing time; ③ The installation cost and maintenance cost are low because the final settling basin and sludge return are not necessary; ④ It is highly applied to small and medium-sized facilities because it has high merit of easy operation through automation of operation and easy adjustment of driving factors according to the characteristics of inflowing water, so that it can flexibly respond to environmental changes.

Recently, a sequencing batch biofilm reactor (SBBR) has been introduced in which a medium capable of securing various microorganisms is introduced into a continuous batch reactor. SBBR can be applied as a nitrogen / phosphorus removal process suitable for small-scale plants by taking advantage of the continuous batch reactor and the advantages of the biofilm process. In most cases, fixed media (EBPR) is used in a continuous batch reactor in the form of enhanced biological phosphorus removal (EBPR), and nitrogen and phosphorus can be simultaneously removed even in the case of using a floating media. In particular, SBBR produces less nitrite and nitrate nitrogen than ammonia nitrogen oxidizes under aerobic conditions, so that SND (simultaneous nitrification and denitrification) in which anaerobic and aerobic conditions exist in the biofilm is formed at the same time. Nitrification and denitrification are possible. However, if the biofilm becomes too thick, it is difficult to remove phosphorus, which causes the need for backwashing at regular intervals.

In the sedimentation stage of the continuous batch reactor, the aeration and agitation are stopped, and the activated sludge and the treated water are separated into solids by gravity, and the decanter is generally discharged using a decanter to discharge the supernatant (treated water). The level of the reactor is lowered as it is. In the process of discharging the treated water, generally, about 50 to 60% of the treated water is discharged after the reaction. If the amount exceeds 60%, sludge washout occurs, which may cause deterioration of the treated water quality. Because there is. In particular, when the filamentous microorganism grows and sludge bulking occurs that makes it difficult to separate the sludge and the treated water, it is impossible to discharge the treated water smoothly.

This is most likely due to changes in the influent sewage, abnormal operation of the treatment plant, including increased carbohydrate content in the influent sewage, lack of dissolved oxygen during aeration, excessive or undersized sludge (MLSS) in the reactor, and low solids residence time. (SRT), high aeration tank residence time, temperature drop, etc., which cause serious operational problems. Controlling such sludge swelling includes controlling the reactor MLSS concentration by adjusting excess sludge waste volume, adjusting dissolved oxygen, adding alum or chlorine (NaOCl), and the most practical method is to replace the sludge. In this case, it takes a long time for the operation of the treatment plant to operate normally.

In addition, the decanter installed for the discharge of treated water is expensive and in the case of failure, the operation of the decanter is stopped.

Recently, the Ministry of Environment integrates the existing sewage and manure laws into the sewerage system. Major changes to the sewage legislation that are being implemented include obligations to reclaim treated water in public sewage treatment facilities to strengthen discharge water quality standards and promote water circulation. According to one days capacity 50m ³ or more sewage treatment facilities for effluent water quality standards for strengthening the same as the public sewage treatment plants BOD, SS 10㎎ / ℓ or less, total nitrogen 20㎎ / ℓ or less, total phosphorus 2㎎ / ℓ or less In addition, the amendment has been revised to comply with the coliform count below 3,000 / ml, and the existing facility will apply the revised law from January 1, 2012. Therefore, the size of the market for biological advanced treatment technologies (including new and advanced treatment conversion projects) suitable for small sewage treatment facilities is expected to increase rapidly.

In order to solve the problems occurring in the existing continuous batch reactor, the present invention can cope with sludge swelling and maintain a high concentration of sludge in the reactor to increase biological nitrogen and phosphorus treatment efficiency. An apparatus and a method thereof are provided.

The present invention is a reaction tank (1); A stirrer (2) provided inside the reactor; An acid pipe (3) provided at an inner lower end of the reactor; A sewage inlet 4 connected to the side of the reactor; A treated water outlet 5 connected to the lower side of the reactor; It provides a biological sewage treatment apparatus including a stirrer, an diffuser, a sewage inlet and a treatment water outlet connected to the control unit (6); and a reactor level sensor (7) connected to the control unit.

In addition, (a) by introducing the sewage into the reaction tank containing the sludge and stirring, mixing the sludge and the sewage, inducing denitrification and phosphorus release reaction; (b) aeration of the sewage to induce nitrification and phosphorus intake; (c) stirring the sewage to induce denitrification; (d) solid-liquid separation of the sewage from which the reaction is completed using sludge and treated water using a microfiber cloth; And (e) provides a biological sewage treatment method comprising the step of discharging the separated treated water.

In addition, as a biological sewage treatment method using the sewage treatment apparatus, (a) the sewage is introduced into the reaction tank (1) containing the sludge through the sewage inlet (4), stirred with a stirrer (2), sludge and sewage Mixing and inducing a denitrification reaction and a phosphorus release reaction; (b) aeration of sewage using an acid pipe (3) to induce nitrification and phosphorus intake; (c) inducing denitrification by stirring the sewage with a stirrer (2); (d) solid-liquid separation of the sewage from which the reaction is completed into sludge and treated water using microbubbles generated from the diffuser (3); And (e) provides a biological sewage treatment method comprising the step of discharging the separated treated water through the treated water outlet (5).

When the sewage altitude treatment apparatus including the continuous batch reactor combined with the sludge flotation method according to an embodiment of the present invention and the sewage altitude treatment method using the same, the biological treatment efficiency of organic matter, nitrogen and phosphorus in response to the sludge swelling phenomenon perfectly This can be increased. When using the sewage treatment apparatus and the sewage treatment method using the same according to an embodiment of the present invention, there is almost no loss of sludge even when discharging more than about 75% of the treated water, it is possible to increase the concentration of sludge in the reaction tank To increase the overall processing time. In addition, expensive decanters, which were necessary for the discharge of the treated water in the conventional continuous batch reactor, do not require an expensive decanter, thereby reducing installation and maintenance costs. On the other hand, when the sludge flotation using air, sufficient oxygen is supplied so that the dissolved oxygen concentration of the treated water is maintained at 5 to 6 mg / L or more, thereby preventing adverse effects on the water ecology due to oxygen depletion in the discharge water.

The present invention combines the sludge flotation method and the continuous batch reactor, by adopting the flotation separation method instead of the gravity sedimentation step, sewage altitude treatment apparatus that can minimize the effect of sludge loss and sludge swelling on the treated water quality and the same Provides an advanced sewage treatment method.

1 is a block diagram of a sewage altitude treatment apparatus including a continuous batch reactor combined with a sludge flotation method according to an embodiment of the present invention, Figure 2 is a sewage altitude using the sewage altitude treatment apparatus according to an embodiment of the present invention. A schematic flowchart of the treatment method.

Biological sewage treatment apparatus including a continuous batch reactor combined with a sludge flotation method according to an embodiment of the present invention is a reaction tank (1); A stirrer (2) provided inside the reactor; An acid pipe (3) provided at an inner lower end of the reactor; A sewage inlet 4 connected to the side of the reactor; A treated water outlet 5 connected to the lower side of the reactor; The control unit 6 is connected to the stirrer, the diffuser, the sewage inlet and the treated water outlet; and a reactor level sensor 7 connected to the control unit. In particular, the sewage inlet and the treated water outlet may be connected to one pump 8, and the pump may be connected to the controller to alternately operate the sewage inlet and the treated water outlet. In addition, the diffuser may be connected to an air compressor 9, and the air compressor may be connected to a control unit to adjust the air pressure of the air compressor.

The reaction tank 1 may be supplied with sewage from the storage tank 11 through a pump 8 connected to the sewage inlet 4. Sewage is supplied into the reactor 1 through a distribution pipe, and the sewage inflow point may be located at one of the lower and upper portions of the reactor for convenience. In the reactor 1, highly concentrated sludge may be seeded, or there may be a highly concentrated sludge by flotation in a previous cycle. When the sewage flows into the reactor 1 and the water level is higher than the impeller of the stirrer 2 located above the inside of the reactor, the stirrer 2 is operated by the control unit 6 connected to the reactor water level sensor 7 and is introduced. The sewage and the highly concentrated sludge in the reactor 1 are uniformly mixed. If the sewage inflow continues and the sewage water level in the reactor 1 rises to a certain portion, the sewage inflow may be blocked by the controller 6 which is linked to the pump 8 connected to the sewage inlet 4. Stirring continues even after the sewage inlet is shut off.

The step may be performed for about 55 to 65 minutes, and the reaction of the denitrification of nitrogen oxides remaining in the sewage and release of phosphorus proceeds in the reactor due to the inflow and agitation of the sewage.

In the state where the mixing process is performed by the stirrer 2, the aeration step may be started while oxygen is supplied from the diffuser 3 provided at the lower end of the reactor. The process can be maintained for about 80 to 100 minutes, in which the excess intake of phosphorus and the oxidation (nitrification) reaction of organic matter and ammonia nitrogen are carried out. At this time, the oxygen supply from the diffuser (3) is made by adjusting the air pressure of the air compressor (9) connected to the diffuser, and the air pressure is adjusted to within 2.5 ~ 3.0 kg _f / cm ² by the controller 6 Can be maintained. The diffuser 3 may have a strength at which the deformation of the shape does not appear at a maximum of 6.0 kg _f / cm ² .

When the aeration step is completed, the control unit 6 may stop the air supply to the diffuser. Thereafter, only the stirrer 2 may be operated for about 40 to 60 minutes to induce smooth mixing. In the non-aeration stirring step, the denitrification reaction of nitrous acid or nitrate nitrogen proceeds, and the denitrification reaction may be endogenous denitrification or an organic substance remaining in the reaction tank. In addition, the organic matters deficient in denitrification in the above step may be supplied by injecting methanol or the like from the outside or additionally supplying sewage of about 10-20% of the initial sewage inflow.

After the progress of the stirring step, the solid-liquid separation step of the sludge for the treatment water discharge may proceed. By introducing a sludge flotation method according to an embodiment of the present invention, it is possible to perfectly cope with the sludge swelling phenomenon which frequently occurs in an actual operation situation and adversely affects the treatment efficiency of a continuous batch reactor. In addition, the process operation is very stable and easy to perform because no change in operating factors to solve the problems caused by the sludge swelling, the addition of chemicals to suppress the growth of filamentous fungi, and the sludge seeding are required.

Floating solid-liquid separation of the sludge may be started by generating microbubbles from the diffuser 3. The micro bubble (size: 40 ~ 80μm) can be generated by adjusting the pressure of the air injected into the diffuser 3 from the control unit 6, the air pressure to be maintained at 1.5 to 2.0 kg _f / cm ² Can be. The sludge flotation step may be performed for 40 minutes to 60 minutes, and the suspended solids separation of the sludge and the treated water is started while the microbubbles are supplied. As a result, the sludge is concentrated in the upper part of the reaction tank and the treated water is located at the lower part of the reaction tank so that the treated water can be discharged through the treated water outlet 5 connected to the lower side of the reaction tank.

Finally, the discharge of the treated water can proceed with the sludge flotation solid separation completed. Specifically, the treated water is discharged through the treated water outlet 5 on the lower side of the reactor, which can be discharged by operating the pump 8 connected to the treated water outlet 5 in the controller 6. Sewage advanced treatment apparatus according to an embodiment of the present invention can reduce the installation cost and maintenance costs because no expensive decanter was required for the discharge of the treated water in the conventional continuous batch reactor. When the water level in the reactor is lowered to a certain portion, the control unit 6 may stop the operation of the pump 8 to block the treatment water outflow. The amount of treated water discharged from the reactor may be about 75% or more of the total treated water volume. Unlike the conventional continuous batch reaction process, even if more than about 75% of the total volume of treated water is discharged, there is little sludge loss in the reaction tank, thereby increasing the treatment capacity and increasing the concentration of microorganisms in the reactor, thereby increasing the treatment efficiency. Can be. The discharge step may proceed for about 15 to 25 minutes.

In addition, by using the pump (8) to draw a sludge separated in a high concentration through the sludge discharge unit 10 connected to the reactor (1) it is possible to adjust the solid retention time (solid retention time, SRT).

Through the above steps, one cycle of the sewage treatment system including the continuous batch reactor combined with the sludge flotation method according to one embodiment of the present invention is completed, and the cycle may be repeated a plurality of times.

Hereinafter, the present invention will be described in more detail with reference to Examples.

<Example>

1) Experiment apparatus and method

In this embodiment, a 70L continuous batch reactor as shown in FIG. 1 was manufactured and used, and a lower portion thereof was equipped with an acid pipe for generating microbubbles for flotation and separation of sludge. Allowing both overdose and flotation. The operating cycle in this embodiment is shown in Table 1, the sludge concentration (MLSS) in the reactor is 4,500 ~ 5,500 mg / L (average 5,000 mg / L), the sludge residence time is 30 days, the operating temperature is 15 ~ 22 ° C, and the treated water discharge rate per operation cycle was 75% of the influent sewage. In this embodiment, the sludge swelling process is performed using sludge (SVI = 95 mL / g) and poor sludge (SVI = 300 mL / g) based on the sludge volume index (SVI). Performance was also reviewed. In this example, inflow sewage from the sewage treatment plant of Gyeonggi-do was collected and used after refrigeration at 10 ° C or lower, and planting sludge was also used in the same place.

On the other hand, in order to induce the swelling phenomenon of the sludge artificially lower the water temperature and dissolved oxygen (DO), and the sludge swelling phenomenon while operating a reactor to introduce a high maintenance content, nitrogen and phosphorus-free artificial wastewater Growth of filamentous fungi was promoted. The reactor operation was continued until the SVI value is 300 mL / g or more, and then the sludge was operated by planting a continuous batch sewage treatment apparatus combined with the sludge flotation method of the present invention.

Unit: minute Inflow / Stirring Aeration Stirring Separation Discharge Total driving time Example 60 90 60 40 20 270

2) Experiment result

Experimental results of this example are shown in Table 2 inflow sewage properties and treated water quality. For organic matter, sewage with an average of 120 mg / L BOD and an average of 185 mg / L COD was introduced. The I water quality of the treated water in the reactors planted using ordinary sludge (SVI = 95 mL / g) was 4.0 Analysis of mg / L BOD and 9.1 mg / L COD confirmed that the treatment efficiency is more than 95%. In addition, the water quality analysis of treated water II in the reactor planted with bulking sludge (SVI = 300 mL / g) showed similar results to the concentration of organic matter in treated water I. The phenomenon was not found.

In the case of total nitrogen (TN) and total phosphorus (TP), as in the case of organic matter, the treatment efficiency I and II were not inhibited when the treated waters I and II were compared. The total water (TN) was below 10 mg / L and the total phosphorus (TP) was below 1 mg / L. This value satisfies the enhanced discharge water quality for sewage treatment plants with a treatment capacity of 50 m ³ or more.

On the other hand, when sludge swelling occurs, first of all, the removal efficiency of SS (Suspended Solids) in the effluent is lowered, because a large amount of sludge in the treated water flows out simultaneously as the sludge deteriorates. In this case, the sludge concentration (MLSS) in the reactor is gradually lowered and normal operation is impossible. However, as shown in Table 2, when the sewage treatment method according to the present embodiment was used, the SS removal efficiency was very stably maintained even in a situation where the sludge settling property was deteriorated. In this example, the concentration of SS in the average treated water was analyzed as 3.0 mg / L when the general sludge was planted (treated water I), and the concentration was analyzed as 2.0 mg / L when the bulking sludge was used (treated water II). Rather, SS removal efficiency slightly increased even in the sludge expanded state.

Influent sewage properties Influent concentration range (average) (mg / L) Treated Water I Treated Water II Concentration range (average value) (mg / L) Average Processing Efficiency (%) Concentration range (average value) (mg / L) Average Processing Efficiency (%) BOD ₅ 73-156 (120) 1.5 ~ 7.6 (4.0) 96.7 1.2 ~ 6.3 (3.5) 97.1 COD _Cr 120-325 (185) 11.0-42.0 (9.1) 95.1 10.0-38.0 (9.8) 94.7 SS 62-360 (156) 2.0-8.0 (3.0) 98.1 2.0 ~ 6.0 (2.0) 98.7 T-N 14.9-68.0 (31.3) 3.1 ~ 17.3 (8.6) 72.5 3.8 ~ 16.3 (8.2) 73.8 T-P 1.2 ~ 6.1 (3.6) 0.3 ~ 2.8 (0.5) 86.1 0.3 ~ 2.9 (0.6) 83.3

1 is a block diagram of a sewage treatment apparatus including a continuous batch reactor combined with a sludge flotation method according to an embodiment of the present invention.

2 is a schematic flowchart of a sewage altitude treatment method using an apparatus for treating sewage altitude according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

1: reactor 2: stirrer

3: diffuser 4: sewage inlet

5: treated water outlet 6: control unit

7: reactor water level sensor 8: pump

9: air compressor 10: sludge discharge section

11: reservoir

Claims (17)

A biological sewage treatment apparatus including a continuous batch reactor combined with a sludge flotation method, Reactor 1; A stirrer (2) provided inside the reactor; An acid pipe (3) provided at an inner lower end of the reactor; A sewage inlet 4 connected to the side of the reactor; A treated water outlet 5 connected to the lower side of the reactor; A controller 6 connected to the stirrer, the diffuser, the sewage inlet and the treated water outlet; and Biological sewage treatment apparatus comprising a reactor level sensor (7) connected to the control unit. The method of claim 1, The sewage inlet and the treated water outlet are connected to one pump (8), the pump is connected to the control unit biological sewage treatment apparatus, characterized in that for alternately operating the sewage inlet and the treated water outlet. The method of claim 1, The diffuser is connected to an air compressor (9), the biological sewage treatment apparatus, characterized in that the air compressor is connected to the control unit. The method of claim 3, The control unit biological sewage treatment apparatus, characterized in that for adjusting the air pressure of the air compressor. A biological sewage treatment method comprising a continuous batch reaction process in which sludge flotation is combined, (a) introducing sewage into a reaction tank containing sludge and stirring the mixture to induce sludge and sewage and induce denitrification and phosphorus release; (b) aeration of the sewage to induce nitrification and phosphorus intake; (c) stirring the sewage to induce denitrification; (d) solid-liquid separation of the sewage from which the reaction is completed using sludge and treated water using a microfiber cloth; And (e) biological sewage treatment method comprising the step of discharging the separated treated water. The method of claim 5, Step (a) is 55 to 65 minutes, (b) step 80 to 100 minutes, (c) step 40 to 60 minutes, (d) step 40 to 60 minutes, and step (e) 15 to 25 Biological sewage treatment method characterized in that carried out for minutes. The method of claim 5, In the step (c), the biological sewage treatment method, characterized in that further injection of sewage or carbon source. The method of claim 5, In step (e), the biological sewage treatment method characterized in that the discharged treated water at least 75% of the total treated water volume. The method of claim 5, The aeration of the step (b) is carried out with an air pressure of 2.5 ~ 3.0 kg _f / cm ² , the microbubble of the step (d) biological sewage, characterized in that generated by the air pressure of 1.5 ~ 2.0 kg _f / cm ² Treatment method. The method according to any one of claims 5 to 9, Biological sewage treatment method characterized in that for repeating the cycle a plurality of times (a) to (e) step (cycle). As a biological sewage treatment method using the sewage treatment apparatus according to any one of claims 1 to 4. (a) introducing sewage into the reaction tank (1) containing sludge through the sewage inlet (4), stirring with a stirrer (2), mixing the sludge and sewage and inducing denitrification and phosphorus release reaction; (b) aeration of sewage using an acid pipe (3) to induce nitrification and phosphorus intake; (c) inducing denitrification by stirring the sewage with a stirrer (2); (d) solid-liquid separation of the sewage from which the reaction is completed into sludge and treated water using microbubbles generated from the diffuser (3); And (e) discharging the separated treated water through the treated water outlet (5). The method of claim 11, In the step (a), the reactor water level sensor 7 detects the sewage level flowing into the reactor 1, and the stirrer 2 is operated by the controller 6 connected to the reactor water level sensor 7. Biological sewage treatment method. The method of claim 12, When the sewage water level introduced into the reactor 1 exceeds a predetermined level, biological sewage, characterized in that the sewage inflow through the sewage inlet 4 is blocked by the control unit 6 connected to the reactor water level sensor 7. Treatment method. The method of claim 11, In the step (b), the biological sewage treatment method characterized in that the air pressure injected into the diffuser (3) by the control unit 6 is adjusted to 1.5 ~ 2.0 kg _f / cm ² . The method of claim 11, In step (c), the biological sewage treatment method, characterized in that the injection of air to the diffuser (3) is blocked by the control unit (6). The method of claim 11, In step (d), the biological sewage treatment method characterized in that the air pressure injected into the diffuser (3) by the control unit 6 is adjusted to 2.5 ~ 3.0 kg _f / cm ² . The method of claim 11, In the step (e), when the treated water level in the reaction tank 1 is less than the predetermined level, the treatment water outflow through the treated water outlet 5 is blocked by the control unit 6 connected to the reactor water level sensor (7). Biological sewage treatment method characterized in that.

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