KR100839035B1 - Biological wastewater treatment apparatus using diffuser-mediated sludge flotation and treatment method using the same - Google Patents

Abstract

An apparatus and a method of wastewater treatment are provided to remove organic matters, nitrogen, phosphorous, particulate matters, etc. in wastewater more effectively by combining an advanced wastewater treatment process with sludge flotation and concentration using micro-bubbles generated in the upward direction by a diffuser, thereby maintaining a high concentration of activated sludge and reducing a solid/liquid separation time of the sludge at the same time. An apparatus of biological wastewater treatment through solid/liquid separation comprises: a pre-denitrifying tank(11) into which raw water flows through a raw water inflow line(18); an intermittent aeration tank(12) into which raw water passing through the pre-denitrifying tank flows; a flotation solid/liquid separator(13) into which an activated sludge mixed solution discharged from the intermittent aeration tank flows to separate treated water and activated sludge from the activated sludge mixed solution; a sludge dispersing inflow unit(17) through which the activated sludge mixed solution flows into the solid/liquid separator; a treated water discharge line(21) which is positioned above the diffuser on a lower part of the solid/liquid separator, and through which the treated water in the activated sludge mixed solution is discharged; a diffuser(31) for generating micro-bubbles in the upward direction to perform solid/liquid separation and concentration of a solid mixed solution comprising activated sludge of the flotation solid/liquid separator in the upward direction; a floating sludge discharge guide(16) through which floated high concentration activated sludge is discharged to a sludge storage tank(15) along an inclined face; a sludge return line(20) along which the high concentration activated sludge of the sludge storage tank is returned to the pre-denitrifying tank; and a treated water storage tank(14) for storing treated water discharged from the flotation solid/liquid separator and intermittently injecting the treated water into a position on the flotation solid/liquid separator lower than that of the diffuser on the flotation solid/liquid separator through a treated water circulating line(22).

Description

BIOLOGICAL WASTEWATER TREATMENT APPARATUS USING DIFFUSER-MEDIATED SLUDGE FLOTATION AND TREATMENT METHOD USING THE SAME}

1 is a view schematically showing a biological sewage treatment apparatus combining the floating solid-liquid separation tank according to the present invention.

2 is a view schematically showing an embodiment of the design and arrangement method of the floating solid-liquid separation process according to the present invention.

* Description of the symbols for the main parts of the drawings *

11: total denitrification tank 12: intermittent aeration tank

13: floating solid-liquid separation tank 14: treated water storage tank

15: Sludge storage tank 16: Floating sludge discharge guide

17: sludge dispersion inlet 18: raw water inlet line

20: sludge conveying line 21: treated water outflow line

22: treatment water circulation line 31: diffuser

3-7 show biological oxygen demand (BOD) (FIG. 3), chemical oxygen demand (COD) (FIG. 4), suspended solids (SS) (FIG. 5), total nitrogen (FIG. 6), total phosphorus (FIG. 7). Is a graph showing how the concentration and its removal efficiency change with operation period.

8A and 8B are top and side views, respectively, of an embodiment in which a ceramic membrane diffuser is disposed at the bottom of a flotation vessel in one embodiment of the present invention.

9 is a photograph showing a state in which a compressor for supplying air to the ceramic membrane diffuser is connected to the diffuser in one specific embodiment of the present invention.

The present invention relates to an apparatus and method for treating biological sewage using activated sludge, and more specifically, to combine sludge flotation and concentration using microbubbles generated upward by the diffuser in the sewage treatment process. The present invention relates to a wastewater treatment method and apparatus which can effectively remove organic matter, nitrogen, phosphorus, particulate matter, etc. in the wastewater by maintaining a high concentration and reducing the solid-liquid separation time of the sludge.

In biological sewage treatment processes that remove organic matter, nitrogen and phosphorus from sewage, a collection of microorganisms called activated sludge is a biological solid that plays a key role. The operating efficiency of the sewage treatment process (activated sludge process) using activated sludge depends on the concentration load and flow load of pollutants including organic matter of the influent sewage, the activated sludge concentration and state of the reactor, the hydraulic residence time and the solid residence time. It is greatly affected. In particular, the concentration of activated sludge has been recognized as a very important driving factor not only in typical activated sludge processes but also in advanced sewage treatment processes including nitrogen and phosphorus removal. However, gravity sedimentation, which is most commonly used among the existing solid-liquid separation methods, cannot properly adjust or maintain the activated sludge concentration in the reactor. In particular, sludge swelling caused by intermittent sludge bulking or sedimentation during sludge, sludge re-injury caused by nitrogen gas deterioration, consequent deterioration of solid-liquid separation efficiency and excessive loss of activated sludge are best addressed in gravity settling. It is pointed out as a difficult problem.

The methods developed for the operation of the high concentration activated sludge process include the activated sludge process (Membrane Bioreactor, MBR) using an immersion membrane, the pure oxygen aeration process, and the biofilter method using a carrier which is a typical deposition growth method. When microorganisms are maintained at high concentration in activated sludge process, the organic matter load per unit volume can be increased by increasing the organic matter treatment capacity in the aeration tank, which can reduce the reaction tank volume by 50 ~ 75%, and thus the required site area. Also greatly reduced. In addition, the nitrification rate is expected to be sharply improved according to the increase in the nitric oxide microbial concentration, it is possible to maximize the removal efficiency of ammonia nitrogen. In addition, due to the low F / M ratio (food-to-microorganism ratio), the self-oxidation of sludge is actively progressed and the amount of excess sludge is expected to decrease. However, in the case of the MBR process or the biofilter method, the initial cost according to the purchase of the membrane or the carrier is very large, and the blockage by activated sludge or sludge secretion occurs during a long period of operation, thereby increasing the pressure loss. Therefore, there is a disadvantage in that periodic cleaning or backwashing must be accompanied. In the case of aeration using pure oxygen, stable sedimentation of the sludge must be ensured at all times in order to maintain activated sludge at a high concentration. Therefore, stable operation is impossible and it is difficult to maintain the concentration of microorganisms in the aeration tank above 8,000 mg / L. Known. In addition, there is a disadvantage in that additional costs are required to supply oxygen.

In addition to these methods, a continuous batch process in which a unit process of fill, reaction, settling, draw and idle of sewage and the like in a single reactor is continuously performed according to a predetermined time sequence. A sequencing batch reactor (SBR) process has been developed and applied to wastewater treatment. This method is not only unnecessary secondary sedimentation basin because each unit process is performed in a single reactor, it is easy to control filamentous bacteria and easy construction, which is very advantageous in terms of stable management of sewage. However, this typical or modified SBR process is not only able to maintain a high level of mixed liquor suspended solids (MLSS) at a desired level, but also requires a long time for the precipitation reaction which is almost essential. There is a disadvantage that increases the cycle time of. In addition, the existing SBR process has a disadvantage that the sludge particles are included in the effluent when the water flow characteristics in the reaction vessel is changed in the process of flowing out the treated water.

Meanwhile, in order to shorten the time required for securing the microbial concentration and the precipitation reaction of the reactor, a flotation method may be used, and among these, dissolved air flotation (DAF) is widely used as a prior art. However, the dissolved air flotation method requires a high pressure of 4-5 atm to supply dissolved air and a large-capacity compression device to secure the air volume. There are disadvantages. In order to overcome this drawback, air flotation (AF), which is recently used, generates bubbles by using ceramic membrane diffusers instead of generating bubbles by using dissolved dissolved air. The solid-liquid flotation is separated, and the high-liquid sludge separated from the solid-liquid is transported and removed by a skimmer.

The most important thing in the air flotation (AF) process is to create a very fine bubble in order to float the solids, which must be able to produce a bubble size (40-60 μm) suitable for injury. As a conventional technology related to the generation of microbubbles, there is an example of Republic of Korea Patent No. 331593. In the patent, since the surfactant must be added to the water and the cyclone is separately installed, there is a problem that the size of the bubble cannot be adjusted with the problem that the equipment is complicated, the maintenance and management problem is increased, and the cost is increased. As another conventional technique, an attempt has been made to use an electroflotation (EF) method for generating microbubbles using an electrode plate, but this method also uses a separate electric system such as a rectifier, resulting in high installation costs and long time operation. There was still a problem that scale accumulated on the electrode plate.

In order to solve the above problems, the present invention is to maintain a high concentration of the mixed solution suspended solids (MLSS) in the reaction tank to ensure a high concentration of microorganisms, to provide a technique for maximizing the treated water quality by concentrating the sludge at a high concentration For that purpose. It is also an object of the present invention to provide an apparatus and a method for treating the same, which are economical and have a short settling time, thereby minimizing the treatment plant site area. In addition, by attaching the floating solid-liquid separation tank using micro bubbles to the existing nitrogen and phosphorus removal method, it is possible to operate the high concentration activated sludge process while maintaining the advantages of the existing nitrogen and phosphorus removal process, and to drastically reduce the solid-liquid separation time. It is an object of the present invention to provide.

In order to achieve the above object, the present invention in the biological sewage treatment apparatus through solid-liquid separation, having a diffuser at the bottom for supplying microbubbles to the raw water to be treated sewage, separated by microbubbles from the received raw water It is equipped with a passage for discharging the injured sludge at the top, and provides a biological sewage treatment apparatus through solid-liquid separation, characterized in that it comprises a floating solid-liquid separation tank for discharging the treated water from the sludge separated raw water.

In the biological sewage treatment apparatus through solid-liquid separation of the present invention, a total denitrification tank receiving raw waste water and sludge to be treated in front of the floating solid-liquid separation tank, and a raw apparatus from the total denitrification tank to receive raw water from the total denitrification tank, It further comprises an intermittent aeration tank for discharging raw water to the floating solid-liquid separation tank, receiving the sludge discharged along the passage of the upper portion of the floating solid-liquid separation tank behind the floating solid-liquid separation tank and conveying the sludge to the total denitrification tank And a treated water storage tank for receiving the treated water discharged from the sludge storage tank and the floating solid-liquid separation tank.

In the biological sewage treatment apparatus through solid-liquid separation of the present invention, the floating solid-liquid separation tank further comprises a treatment water outlet line or opening for discharging the treated water on the diffuser at the bottom of the floating solid-liquid separation tank. , The floating solid-liquid separation tank further comprises a skimmer to help the discharge of sludge, the skimmer is characterized in that the operating time is different depending on the injured time required for solid-liquid separation, the floating solid-liquid separation tank is shear and It is divided into two compartments of the rear end, and the front end and the rear end each have a diffuser at the bottom thereof, and the treated liquid separated from the front end is solid-liquid separated again from the rear end, and the floating solid-liquid separation tank separates the solid-liquid separation time of the front and rear ends from each other. It is characterized by driving differently.

In the biological sewage treatment apparatus through the solid-liquid separation of the present invention, the treated water storage tank further comprises a treated water circulation line for intermittently conveying a portion of the treated water received to the bottom of the floating solid-liquid separation tank, the treated water The treated water returned by the circulation line is introduced into the floating solid-liquid separation tank at a lower position than the diffuser in the floating solid-liquid separation tank.

In the biological sewage treatment apparatus through solid-liquid separation of the present invention, the diffuser is characterized in that to generate a microbubble from below the floating solid-liquid separation tank at a pressure of 1.8 ~ 3.0 bar (bar), the diffuser It is characterized in that the ceramic membrane material.

In the biological sewage treatment apparatus through solid-liquid separation of the present invention, the sludge storage tank further comprises means for degassing the bubbles contained in the sludge layer before returning the sludge to the total denitrification tank.

In the biological sewage treatment apparatus through solid-liquid separation of the present invention, the intermittent aeration tank is divided into two compartments, and periodic alternating aeration occurs in each compartment to alternately achieve aerobic and anaerobic conditions for each compartment. It is done.

In addition, the present invention in the biological sewage treatment method through the solid-liquid separation, a) raw water and sludge to be treated in the sewage treatment is introduced into the total denitrification tank denitrification reaction by the sludge microorganisms and phosphorus release reaction, the raw water is moved to the intermittent aeration tank Doing; b) ammonia nitrogen contained in the raw water by the sludge microorganism in the intermittent aeration tank under aerobic conditions is oxidized to nitrate nitrogen in the intermittent aeration tank and excess intake of phosphorus by the sludge microorganism occurs; c) Supplying microbubbles from raw machinery installed at the bottom of the floating solid-liquid separation tank to the raw water received from the intermittent aeration tank to the solid-liquid separation tank, to remove sludge and solids from the raw water to the top of the solid-liquid separation tank, except for the sludge and solids. Separating each of the treated water, which is a liquid component, into the lower portion; d) discharging the treated water separated in the solid-liquid separation tank to the treated water storage tank, and sending the sludge and solids separated from the floating solid-liquid separation tank to the sludge storage tank; And e) returning a portion of the sludge stored in the sludge storage tank to the total denitrification tank, the biological sewage treatment method through solid-liquid separation.

In the biological sewage treatment method through the solid-liquid separation of the present invention, the micro-bubble of step c) is generated upward from the floating solid-liquid separation tank at a pressure of 1.8 ~ 3.0 bar by the diffuser .

In the biological sewage treatment method through the solid-liquid separation of the present invention, the floating solid-liquid separation tank is divided into a front and rear sections, the step c) is a solid-liquid separation in the front end, between the c) and d) step And c ') receiving solids from the rear end of the floating solid-liquid separation tank and subjecting the treated water to the front end of step c) through the supply of microbubbles by an diffuser installed at the bottom, and separating solid-liquid as in step c). Characterized in that.

In the biological sewage treatment method through the solid-liquid separation of the present invention, the time for dwelling in the floating solid-liquid separation tank in step c) is 30-60 minutes, 30-40 minutes in the front end, 10- at the rear end It is characterized by 20 minutes.

In the biological sewage treatment method through solid-liquid separation of the present invention, the treated liquid separated in step d) is discharged through the treated water outlet line or opening located on the diffuser in the lower portion of the floating solid-liquid separation tank. .

In the biological sewage treatment method through the solid-liquid separation of the present invention, the intermittent aeration tank of step b) is divided into two compartments, periodic alternating aeration occurs, characterized in that to achieve aerobic and anaerobic conditions alternately for each compartment , The microbial concentration in the intermittent aeration tank of step b) is characterized in that to maintain more than 3,000mg / L.

In the biological sewage treatment method through the solid-liquid separation of the present invention, characterized in that it further comprises the step of degassing the bubbles contained in the sludge layer before returning the sludge to the total denitrification tank in step e).

In the biological sewage treatment method through the solid-liquid separation of the present invention, the wastewater treatment method is f) a portion of the treated water of the treated water storage tank intermittently returned to the floating solid-liquid separation tank, but lower than the diffuser of the floating solid-liquid separation tank It further comprises the step of returning to the point.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention provides a device in which the solid-liquid separation process by sedimentation is replaced with a sludge flotation concentration process using microbubbles generated upward from the diffuser. Specifically, the present invention is configured to combine the floating solid-liquid separation process using a microbubble in the denitrification + intermittent aeration process that is a representative nitrogen, phosphorus removal process. In particular, there is a feature that can generate micro bubbles through the diffuser with a small air pressure of about 2 atm.

The wastewater treatment method using the sludge flotation solid-liquid separation according to the present invention can maintain a high concentration of microorganisms in the intermittent aeration tank by using a sludge flotation concentration technique that can stably separate solid-liquid at all times regardless of the state of the sludge. It is applicable to all continuous processes involving nitrogen and phosphorus removal.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 schematically shows a wastewater treatment apparatus combining a floating solid-liquid separation tank according to the present invention, and FIG. 2 schematically shows a specific example of a design and arrangement method of the floating solid-liquid separation process according to the present invention. As shown in Fig. 1 and Fig. 2, the raw water from the sewage treatment target or primary sedimentation tank is introduced into the total denitrification tank 11 of the present process through the raw water inflow line 18. In the total denitrification tank 11, denitrification by microorganisms occurs and at the same time organic matter is removed. The hydraulic residence time in the total denitrification tank is about 30 minutes to 1 hour, and stirred by a stirrer as necessary. The raw water passing through the total denitrification tank 11 is introduced into the intermittent aeration tank 12. In the aeration tank, ammonia nitrogen contained in the raw water is nitrated to nitrate nitrogen, and organic matter not removed from the anoxic tank is oxidized and converted into carbon dioxide. On the other hand, the aeration tank is located in the lower end for the oxygen supply device. The intermittent aeration tank 12 has a hydraulic residence time of about 1 hour to 2 hours, and divides the front end and the rear end and does not aeration at the front end when the aeration at the front end (aerobic) (anaerobic), on the contrary, at the front end when aeration at the rear end The aeration process is alternately aerated at intervals of about 30 minutes to 1 hour (see FIG. 1). This is to maximize the removal of organic matter and nitrogen by microorganisms are alternately exposed to aerobic and anaerobic conditions.

The activated sludge mixed liquid flowing out from the intermittent aeration tank flows into the floating solid-liquid separation tank 13 to separate the treated water and the activated sludge. Of the activated sludge mixed solution introduced into the solid-liquid separation tank through the sludge dispersion inlet device 17, the treated water has a downward flow and is located at the lower end, and the treated water outlet line 21 or the opening placed above the diffuser pipe is opened. Will be discharged through. While the treated water has a downward flow, the diffuser placed at the bottom generates air by introducing air at a pressure of 1.8 to 3.0 bar.

In the present invention, the diffuser can widen the surface area where the microbubbles are exposed, and if the bubble can be generated at the pressure of 1.8 to 3.0 bar, its specific configuration and arrangement is not particularly limited as long as it can supply air pressure uniformly. In a specific embodiment of the present invention, a plurality of cylindrical diffusers are arranged alternately to secure the maximum surface area and to avoid interference between the generated microbubbles, which are shown in FIGS. 8A and 8B. . FIG. 9 is a photograph showing a state in which a compressor (10HP capacity) for supplying air to the diffuser is connected in this embodiment. In one specific embodiment of the present invention, the diffuser is preferably a ceramic membrane material.

The solid mixed solution including the activated sludge of the floating solid-liquid separation tank 13 is solid-liquid separated and concentrated upward by the microbubbles generated upward by the diffuser 31. The microbubbles generated in a large amount by the diffuser 31 move upward and come into contact with biological solids including activated sludge. In this process, the activated sludge floc is floated to the surface due to the small specific gravity caused by the attached microbubbles.

In order to increase the solid floating effect by the microbubbles should be able to generate the size of the microbubbles in a constant and optimized size, in one specific embodiment of the present invention the size of the microbubbles is controlled by the pressure of the injected air. To achieve high concentrations of concentrated sludge (20,000 mg / L or more), which is targeted for more efficient bioreactor operation than gravity precipitation, air pressure is typically operated at 2.3-2.5 bar on a pilot scale (100 tonnes per day). .

The floating solid-liquid separation tank 13 may be separated into solid-liquid separation by second-flooding the outflow water from the lower part after firstly injuring by driving in two stages as necessary. The reason for operating the two-stage flotation process is to prepare for the case that the lower runoff after the first injury due to problems in the diffuser is not maintained and the initial efficiency is not good. can do. In addition, it is advantageous because the fine bubbles can be more evenly distributed while using the same precipitation tank area. Floating solid-liquid separation time is preferably a total of 30-60 minutes, it is preferable to have a hydraulic residence time of about 40 to 45 minutes in the first stage, 15 to 20 minutes in the second stage. On the other hand, in order to fully float the activated sludge that comes down to the wall surface, the diffuser is inclined toward the wall surface to maximize the floating efficiency as shown in the side view of the ceramic membrane diffuser.

The flotation separated high concentration activated sludge flows out to the sludge storage tank 15 along the inclined surface through the flotation sludge discharge guide 16. In order to smoothly discharge the sludge, the floating solid-liquid separation tank 13 may additionally include other means for assisting the discharge of a skimmer. The high concentration concentrated sludge conveyed to the sludge storage tank 15 is conveyed to the total denitrification tank 11 along the sludge conveying line 20. In this process, the sludge storage tank 15 degass the microbubbles contained in the thickened sludge layer to be introduced into the total denitrification tank operated under anoxic conditions.

Floating separated sludge is not easy to discharge sludge because of the very high concentration of mixed liquid suspended solids (MLSS) above 20,000 mg / L. The present invention stores the treated water flowing out from the floating solid-liquid separation tank in the treated water storage tank 14 for the smooth discharge of the flocculated sludge, but intermittently lower than the diffuser 31 through the treated water circulation line 22. Inject into the floating solids separation tank 13 to the point. When the sludge is discharged in this way, it is possible to ensure the discharge of the activated sludge separated from the flotation, and the back washing of the ceramic membrane diffuser located at the bottom of the sludge flotation solid-liquid separation tank 13 also takes place simultaneously.

According to the present invention, once the sludge is floated in the flotation solid-liquid separation tank 13, there is no fear that the sludge will be settled again by the microbubble existing in the flotation sludge separated and the reaction tank generated in the treatment water outflow process. Since the sludge layer is not separated by the water flow resistance, it is also very unlikely that the solid-liquid separated sludge particles are contained in the effluent. Therefore, the overall suspended solids (SS) removal rate is considerably higher than that of continuous activated sludge processes in typical or modified forms.

When operating this process, organic matters such as biological oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), nitrogen and phosphorus removal rates were demonstrated through Experimental Example 1 below. .

[Experimental example 1]: Floating experiment results of 100 tons of waste water treatment process per day

This experiment is the result of treatment conducted on the 100 ton / day scale using the process specified above. It is the result of processing through total denitrification tank, intermittent aeration tank, sludge flotation solid-liquid separation tank, and the floating solid-liquid separation tank replacing the gravity sedimentation tank of the existing activated sludge method is about 4 m high and into the ceramic membrane diffuser that generates micro bubbles. The air pressure of 1.8 ~ 3.0 bar was put to generate a uniform microbubble.

Table 1 below shows the treatment efficiency during the operation period, and FIGS. 3, 4, 5, 6 and 7 sequentially show the inflow and outflow concentrations and their removal efficiencies for BOD, COD, SS, total nitrogen and total phosphorus, respectively. Graphs shown (average values are listed in Tables 2, 3, 4, 5 and 6). At this time, the concentration of sludge at the top was found that the MLSS is more than 20,000 mg / L and when the injury time exceeds 30 minutes, there is always the effect of solid-liquid separation at high concentrations.

Processing efficiency of the driving period Item unit Yu can Number of treatments Processing efficiency (%) Lowest to highest Average Best ~ First Average BOD ₅ L ^-1 23.3 to 156.3 84.1 2.0 to 8.8 5.5 93 COD _Cr L ^-1 99.5 ~ 325.0 162.7 6.8 to 28.0 17.0 89 Suspended Solids (SS) L ^-1 62.0 to 360.0 166.6 2.0 to 6.3 4.2 97 Total nitrogen (T-N) L ^-1 14.9-68.0 29.8 4.3 to 15.1 7.9 72 Total phosphorus (T-P) L ^-1 1.0 to 6.2 3.4 0.2 to 1.3 0.5 84

(1) BOD removal efficiency

In order to measure the efficiency of BOD removal, the amount of biological dissolved oxygen was measured using the diaphragm method on the water environmental process test method.

 BOD Removal Efficiency Driving period Contaminant Concentration (mg / L) % Removal efficiency (average) Inflows (average) Outflow (average) '06. 10.24 ~ '07. 03.23 23.3 ~ 156.3 (84.1) 2.0-8.8 (5.5) 84.3 ~ 97.5 (93.3)

(2) COD _Cr Removal Efficiency

COD was measured using standard methods prescribed by the US Environmental Protection Agency (EPA).

COD removal efficiency Driving period Contaminant Concentration (mg / L) % Removal efficiency (average) Inflows (average) Outflow (average) '06. 10.24 ~ '07. 03.23 99.5-325.0 (84.1) 6.8 ~ 28.0 (17.0) 82.5 ~ 94.8 (89.0)

(3) SS removal efficiency

The removal efficiency of suspended solids was measured using standard methods prescribed by the US Environmental Protection Agency.

SS removal efficiency Driving period Contaminant Concentration (mg / L) % Removal efficiency (average) Inflows (average) Outflow (average)  '06. 10.24 ~ '07. 03.23 62.0 ~ 360.0 (166.0) 2.0 ~ 6.3 (4.2) 94.2 ~ 98.9 (97.5)

(4) nitrogen removal

The total amount of nitrogen in the wastewater was measured using standard methods prescribed by the US Environmental Protection Agency.

Total Nitrogen Removal Efficiency Driving period Contaminant Concentration (mg / L) % Removal efficiency (average) Inflows (average) Outflow (average) '06. 10.24 ~ '07. 03.23 14.9-68.0 (29.8) 4.3 ~ 15.1 (8.2) 45.0 ~ 84.0 (72.0)

(5) phosphorus removal

Total phosphorus in wastewater was measured using standard methods prescribed by the US Environmental Protection Agency.

Total Phosphorus Removal Efficiency Driving period Contaminant Concentration (mg / L) % Removal efficiency (average) Inflows (average) Outflow (average) '06. 10.24 ~ '07. 03.23 1.2-6.0 (3.4) 0.2 ~ 1.3 (0.5) 60.9 ~ 94.7 (85.0)

When the process containing the high concentration of microorganisms is stably operated by the present invention, the volume of the reactor can be reduced first and the inflow rate of the treatment and the loading rate of the pollutant can be increased as compared with the biological treatment apparatus of the prior art. In addition, since it is configured to replace the gravity sedimentation tank of the existing activated sludge process, it is possible to efficiently treat the waste water, even if less than one third of the time required for the solid-liquid separation in the existing process. Therefore, the land area occupied by the solid-liquid separation tank in the process as shown in Figure 1 can be significantly reduced. In most sewage treatment plants employing activated sludge processes, if sludge swelling or an increase in microflocs continues, the sludge loss causes the runoff water quality to deteriorate rapidly, making the operation itself impossible. The wastewater treatment apparatus and method according to the present invention can completely improve such instability of the wastewater treatment plant, and the microorganism concentration of the intermittent aeration tank 12 is more than twice that of 2,000 to 3,000 mg / L that the conventional activated sludge method is adopted. Maintenance to improve the removal of biological organics, nitrification, denitrification, phosphorus removal and other contaminants. In addition, the excess sludge discharged through the sludge conveying line 20 in order to maintain the proper solids concentration and solids retention time (SRT) of the intermittent aeration tank 12 is dehydrated This is excellent and reduces the final disposal cost of sludge.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention described in the claims below. It will be appreciated.

The wastewater treatment apparatus and method using sludge flotation solid-liquid separation according to the present invention is a wastewater treatment apparatus and method for effectively removing organic matter, nitrogen, phosphorus and particulate matter in the wastewater, and the expected effects are as follows.

First, the high concentration of biological solids can be stably solid-liquid separated, so that the MLSS concentration of the intermittent aeration tank (bioreactor) can be maintained at a desired level. If the concentration of the microorganism in the bioreactor is kept high, it is possible to operate for a high organic load rate, and the hydraulic retention time can be drastically shortened, thereby increasing the treatment capacity within a predetermined time, thereby increasing the overall treatment efficiency. In addition, an increase in the concentration of the reaction tank microorganisms leads to an increase in the concentration of nitrifying and phosphorus removing microorganisms, thereby improving the nitrification rate and phosphorus removal efficiency for ammonia nitrogen in the wastewater.

Second, since the sludge flotation concentrates instead of the precipitation process in the existing activated sludge process, the required area of solid-liquid separation tank can be reduced by reducing the time required for solid-liquid separation to be less than 1/3 compared to the precipitation process.

Third, the flotation sludge concentrated in the solid-liquid separation process contains a large amount of bubbles. Therefore, biological solids do not flow out when the treated water is discharged, so the overall SS removal rate is improved compared to the conventional activated sludge process. In the case of the existing activated sludge process, the treated water quality is greatly influenced by the change of the sludge state such as the occurrence of microfloc or the sludge swelling phenomenon, whereas the sludge flotation concentration according to the present invention enables a very stable solid-liquid separation, which is always good. Treated water quality can be obtained. In addition, the excess sludge discharged contains a large amount of bubbles, which is excellent in dehydration and can reduce the final disposal cost of the sludge.

Claims (21)

In the biological sewage treatment apparatus through solid-liquid separation, Equipped with a diffuser at the bottom for supplying microbubbles to the raw water subject to sewage treatment, Equipped at the top with a passage for discharging the sludge separated by microbubble from the received raw water, A floating solid-liquid separation tank for discharging the treated water from which sludge is separated from raw water, The diffuser is characterized in that to generate a microbubble from below the floating solid-liquid separation tank at a pressure of 1.8 ~ 3.0 bar (bar), biological sewage treatment apparatus through solid-liquid separation. The method of claim 1, A total denitrification tank for receiving raw water and sludge subject to wastewater treatment in front of the floating solid-liquid separation tank and Receiving raw water from the total denitrification tank, and equipped with an aerator for aeration, and further comprises an intermittent aeration tank for discharging the raw water to the floating solid-liquid separation tank, A sludge storage tank receiving sludge discharged along the passage of the upper part of the floating solid-liquid separation tank behind the floating solid-liquid separation tank and conveying the sludge to the total denitrification tank; Further comprising a treated water storage tank for receiving the treated water discharged from the floating solid-liquid separation tank, biological sewage treatment apparatus through solid-liquid separation. The method according to claim 1 or 2, The floating solid-liquid separation tank further comprises a treatment water outlet line or an opening for discharging the treated water on the diffuser at the bottom of the floating solid-liquid separation tank, biological sewage treatment apparatus through solid-liquid separation. The method according to claim 1 or 2, The floating solid-liquid separation tank further includes a skimmer for assisting the discharge of sludge, wherein the skimmer is different in its operating time according to the injured time required for solid-liquid separation, biological sewage treatment apparatus through solid-liquid separation . The method of claim 2, The treated water storage tank further includes a treated water circulation line for intermittently conveying a portion of the treated water received to the lowered solid-liquid separation tank, and the treated water returned by the treated water circulation line is the suspended solid-liquid separation tank. Biological sewage treatment apparatus through solid-liquid separation, characterized in that the flow into the floating solid-liquid separation tank at a lower position than the acid diffuser. The method of claim 1, The floating solid-liquid separation tank is divided into two compartments, a front end and a rear end, The front end and the rear end each include a diffuser in the lower part, Biological sewage treatment apparatus through solid-liquid separation, characterized in that the solid-liquid separation of the treated water separated from the front end solids. The method of claim 6, Said floating solid-liquid separation tank is characterized in that the operation of the solid-liquid separation time of the front and rear end differently, biological sewage treatment apparatus through solid-liquid separation. delete The method of claim 1, The diffuser is characterized in that the ceramic membrane material, biological sewage treatment apparatus through solid-liquid separation. The method of claim 2, The sludge storage tank further comprises a means for degassing the bubbles contained in the sludge layer before returning the sludge to the total denitrification tank, biological sewage treatment apparatus through solid-liquid separation. The method of claim 2, The intermittent aeration tank is divided into two compartments, and periodic alternating aeration occurs in each compartment to alternately achieve aerobic and anaerobic conditions for each compartment, biological sewage treatment apparatus through solid-liquid separation. In the biological sewage treatment method through solid-liquid separation, (a) the raw water and sludge to be treated in the sewage treatment process are introduced into the total denitrification tank to cause denitrification and phosphorus release reaction by the sludge microorganisms, and then the raw water is moved to the intermittent aeration tank; (b) ammonia nitrogen contained in the raw water by the sludge microorganism in the intermittent aeration tank under aerobic conditions is oxidized to nitrate nitrogen in the intermittent aeration tank and excess intake of phosphorus by the sludge microorganism occurs; (c) to the raw water received from the intermittent aeration tank into the floating solid-liquid separation tank, by supplying microbubbles generated at a pressure of 1.8 to 3.0 bar from the diffuser installed at the lower end of the floating solid-liquid separation tank, sludge and Separating solids from the treated water, which is a liquid component except the sludge and solids, to the top of the solid-liquid separation tank, respectively; (d) discharging the treated water solid-liquid separated from the floating solid-liquid separation tank to the treated water storage tank, and sending the sludge and solids separated from the floating solid-liquid separation tank to the sludge storage tank; (e) returning a portion of the sludge stored in the sludge storage tank to a total denitrification tank, biological sewage treatment method through solid-liquid separation. delete The method of claim 12, The floating solid-liquid separation tank is divided into front and rear sections, the step (c) is a solid-liquid separation in the front end, Between step (c) and step d), (c ') receiving the treated water at the front end of the step (c) at the rear end of the floating solid-liquid separation tank and separating the solid-liquid liquid in the same manner as in the step (c) through the supply of the microbubbles by the diffuser installed at the bottom; Characterized in that, biological sewage treatment method through solid-liquid separation. The method of claim 12, In step (c), the time the raw water stays in the floating solid-liquid separation tank is 30 to 60 minutes, biological wastewater treatment method through solid-liquid separation. The method of claim 14, The raw water stays in the floating solid-liquid separation tank is 40 to 45 minutes in the front end, characterized in that 15 to 20 minutes in the rear end, biological sewage treatment method through solid-liquid separation. The method of claim 12, The treatment liquid separated in the solid-liquid separation in step (d) is discharged through the treated water outlet line or opening located on the diffuser below the floating solid-liquid separation tank, biological sewage treatment method through solid-liquid separation. The method of claim 12, The intermittent aeration tank of step (b) is divided into two compartments, periodic alternating aeration occurs, characterized in that to achieve aerobic and anaerobic conditions alternately for each compartment, biological sewage treatment method through solid-liquid separation. The method of claim 12, Degassing the air bubbles contained in the sludge layer prior to returning the sludge to the total denitrification tank in the step (e), biological wastewater treatment method through solid-liquid separation. The method of claim 12, The microbial concentration in the intermittent aeration tank of step (b) is characterized in that to maintain at least 3,000 mg / L, biological sewage treatment method through solid-liquid separation. The method of claim 12, The wastewater treatment method (f) intermittently conveying a portion of the treated water of the treated water storage tank to the floating solid-liquid separation tank, and returning it to a lower point than the diffuser of the floating solid-liquid separation tank, the biological through solid-liquid separation Sewage Treatment Methods.

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