KR20020032649A - Apparatus for treating wastewater by using submerged membrain saparation anaerobic digester - Google Patents

Abstract

PURPOSE: An apparatus for treating wastewater by using submerged membrane separation anaerobic digester is provided to produce methane gas effectively and to decompose organic materials in a short time by using produced biogas. CONSTITUTION: The apparatus comprises a digestion tank(20) which stores wastewater; a separation membrane(30) which is submerged in the digestion tank to filter sludge and suspended solids contained in the wastewater; a discharge pipe(16) of which one end is connected to the inside of the separation membrane and the other end is connected to a water storage tank(1) in order to discharge water permeated through the membrane; a pressure gage(6) which is installed on the discharge pipeline to measure how much the separation membrane is foul; a suction pump(4) which sends the permeated water to the water storage tank; a mixture discharge pipe(17) of which one end is placed on the surface of wastewater in the digestion tank and the other end is connected to a classification tank(7) having additional drainage; a gas supply pipe(18) of which one end is connected to the classification tank and the other end is connected to the inside of the digestion tank; a vacuum pump(8) which is installed on the gas supply pipe to vibrate the separation membrane by supplying the gas stored in the classification tank(7) to the upper part of the separation membrane.

Description

Apparatus for treating wastewater by using submerged membrain saparation anaerobic digester}

The present invention relates to an immersion type membrane separation anaerobic digestion wastewater treatment apparatus, and more particularly, to immerse the separation membrane in the digestion tank so that the anaerobic bacteria are concentrated at a high concentration to treat wastewater treatment, and to facilitate foreign substances formed on the membrane. It relates to an immersion type membrane separation anaerobic digestion wastewater treatment apparatus that can be removed easily.

Conventional treatment methods such as sewage and wastewater using microorganisms are gravity sedimentation that separates microorganisms (sludge) and supernatant by sedimenting sewage and wastewater in general, so the sedimentation rate is very slow and the area of the sedimentation basin is larger than a certain amount. Sewage and wastewater could be separated and treated in solid solution. Therefore, the required site area is large and the solid-liquid separation efficiency is unstable according to the conditions, and there is a disadvantage in that microorganisms in the reaction tank cannot be maintained at a high concentration.

In the case of anaerobic digestion such as methane fermentation, the efficiency is changed according to changes in organic load, temperature, and pH, etc. In order for sufficient methane fermentation, bacteria involved in digestion must be sufficiently present. However, since anaerobic bacteria have a long generation and are very sensitive to environmental conditions, it is not easy to maintain digestive tanks. Therefore, it is pointed out that maintaining anaerobic bacteria has a long residence time. In fact, if the sewage sludge is treated by anaerobic digestion at the sewage terminal treatment plant, it is necessary to maintain the residence time of 20 days or more and maintain the activity of anaerobic bacteria, but such maintenance is not easy. In addition, since the anaerobic digestion process contains anaerobic sludge in the treated effluent, the discharge of the treated water after the digestion process only contaminates the water quality. Therefore, an apparatus for removing sludge is additionally required for discharge into the stream after the extinguishing process. Accordingly, Korean Laid-Open Patent Publication No. 2000-27428 discloses an anaerobic reactor including a precipitation part including a limestone layer and a microbial immobilization layer.

On the other hand, in the aerobic reactor, the conventional solid-liquid separation device is separated from the sludge and the supernatant using a membrane (membrane). For example, Japanese Patent Laid-Open No. 11-253942 discloses a wastewater treatment process using a movable separator, and Korean Laid-Open Patent Publication No. 2000-40751 discloses a livestock wastewater treatment method using a separator process. However, in the case of aerobic reaction tanks, as the number of days of operation increases, the fouling of the membrane occurs, the flux decreases, and the flux must be frequently cleaned or chemically replaced to solve the problem. These phenomena include soluble minerals such as Ca ⁺² , Mg ⁺² , CO ₃ ^-2 , SO ₄ ^-2 , silica, Fe ⁺² and humic acids, fulvic acids, polysaccharides, proteins, DNA, antibiotics, steroids, It is further accelerated by biological metabolic components such as enzymes.

The solid-liquid separation device using a separation membrane includes an immersion type and an external tooth type, and the immersion type also includes a precision filter and an ultrafilter. In the case of the submerged type, a filter is installed in the aeration tank to separate the solids by forming a permeate quantity, that is, a flux using a vacuum pump, and in the case of an external type, a filter is installed outside the aeration tank to force the mixed liquid to circulate in the aeration tank at high speed. At the same time, the flux is formed using a vacuum pump to separate the liquid. In the conventional method, the external tooth type is forced to circulate the mixed liquid in the aeration tank at high speed, and the energy consumption is excessive, and the sludge flux is destroyed and refined, thereby reducing the removal efficiency of contaminants in the aeration tank and dehydration when the sludge is dehydrated. There are disadvantages. However, in the anaerobic digester, there is no example of treating wastewater using a separator.

As a result, the economic burden due to the large area of the anaerobic digestion, long time stay, the need for additional facilities for the removal of solids in the treated water, and the shortening of the life due to the contamination of the membrane is emerging as a problem. Due to these problems, a two-phase anaerobic digestion process, an UASB (upflow anaerobic sludge blanket), and a fluidized bed anaerobic reactor have been developed and operated in some treatment plants, but the results are not satisfactory.

Therefore, the present inventors conducted extensive research to solve the above problems, and as a result, in the anaerobic digestion tank, the anaerobic digestion apparatus capable of automatic membrane cleaning using biogas generated by immersing the membrane in the digester and generating wastewater, When used for the treatment of livestock wastewater and leachate, it was confirmed that decomposition of organic substances and methane generation with high efficiency are possible within a short time, and the present invention was completed based on this.

Accordingly, an object of the present invention is to reduce the required site area, to enable effective wastewater treatment and high-efficiency methane production in a short time, and to automatically clean the membrane to maintain membrane durability and permeability, as well as solids in the effluent. To provide a submerged membrane separation anaerobic digestion wastewater treatment apparatus that does not require an additional device for the removal of.

Immersion type membrane separation anaerobic digestion wastewater treatment apparatus of the present invention for achieving the above object is soaked in the digester, and the sludge and suspended solids contained in the wastewater, the wastewater is stored in the digester. The separation membrane formed, one end is connected to communicate with the inside of the separation membrane, the other end is connected to communicate with the collecting tank is installed separately, the pressure is installed on the line of the permeate discharge pipe to measure the contamination state of the separation membrane A suction pump for transferring a gauge and a liquid permeate filtered from the separation membrane to a sump tank, and one end of which is disposed on an upper surface of the sewage / waste water stored in the digester and the other end is connected to a sorting tank having a separate discharge pipe; One end is connected to the sorting tank, the other end is connected to the digester to the separation membrane And a gas pump disposed below and a vacuum pump installed on the gas supply pipe to transfer gas in the fractionation tank to the lower part of the separation membrane to vibrate the separation membrane.

1 is a view schematically showing an anaerobic digestion apparatus in which a membrane for treating waste water is immersed according to the present invention;

Figure 2 is a schematic view showing a device for cleaning the membrane and the membrane immersed in the digester of the anaerobic digestion apparatus according to the present invention.

Explanation of symbols on the main parts of the drawings

1: sump tank 2: substrate tank

3: capture tank 4: suction pump

5: pump 6: pressure gauge

7: sorting tank 8: vacuum pump

11: outer tank 12: level control sensor

13: gas measuring sensor 14: collecting tube

15: suction pipe 16: permeate discharge pipe

17: wastewater and gas discharge pipe 18: gas supply pipe

19: wastewater discharge pipe 20: digester

30: separator

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

1 is a view schematically showing an anaerobic digestion apparatus in which a membrane for treating waste water is immersed according to the present invention. Referring to FIG. 1, the waste water is stored in the digester 20, and the separation membrane 30 is immersed in the digester 20 so that sludge and suspended solids contained in the waste water are filtered out in the digester of the membrane. One end of the permeate discharge pipe 16 is connected to communicate with the interior of the separation membrane 20, the other end is connected to communicate with the water collecting tank 1 is installed separately. The suction pump 4 is installed on the line of the permeate discharge pipe 16 to transfer the permeate of the liquid filtered from the separator 20 to the water collecting tank 1. One end of the mixture discharge pipe 17 is disposed on the upper surface of the waste water and wastewater stored in the digestion tank 20, and the other end thereof is connected to the fractionation tank 7 having a separate discharge pipe 19. One end of the gas supply pipe 18 is connected to communicate with the fractionation tank 7, and the other end is connected to the digester 20 and positioned below the separation membrane 30. The vacuum pump 8 is installed on the gas supply pipe 18 to transfer the gas in the fractionation tank 7 to the lower portion of the separation membrane 30 to serve to vibrate the separation membrane 30.

On the other hand, the substrate tank 2 is installed separately from the digester 20, the substrate is used as a nutrient source of microorganisms to purify the waste water. The digester 20 and the substrate tank 2 are connected to each other through the supply pipe 15, the pump 5 is installed on the supply pipe 15 to the substrate in the substrate tank 2 to the digester 20 To supply. In addition, the collection tank 3 is connected to the digester 20 and the collection pipe 14 to store the gas generated in the digester 20. Gas measuring sensor 13 is installed on one side of the digester 20 to measure the components of the gas generated in the digester 20, the water level control sensor 12 is installed on one side of the upper in the digester 20 The water level in the digester 20 is sensed.

According to the present invention, the substrate is introduced into the digestion tank 20 through the supply pipe 15 by the suction force of the pump 5 in the substrate tank 2, and the generated gas is collected through the collecting tube 14 through the collecting tank 3. ) The extinguishing mixture liquid and some gas in the digestion tank 20 flow into the fractionation tank 7 through the discharge pipe 17 by the suction force of the vacuum pump 8, and the extinguishing mixture liquid into the external tank 11 through the discharge pipe 19. The gas discharged from the fractionation tank 7 is introduced into the digestion tank 20 at a gas flow rate of 5 to 6 L / min through the gas supply pipe 18 by the vacuum pump 8. The gas component in the digester 20 is collected at a gas sampling port (not shown) and measured by the gas measurement sensor 13, and the level control in the digester 20 is controlled by the level control sensor 12. The permeate of the separation membrane 30 is discharged to the collection tank 1 through the discharge pipe 16 by the suction force of the suction pump 4, the contamination of the separation membrane 30 can be seen through the pressure gauge (6).

Figure 2 is a schematic view showing a device for cleaning the membrane and the membrane immersed in the digester of the anaerobic digestion apparatus according to the present invention. The separation membrane 20 preferable in the present invention is a hollow fiber membrane or a flat membrane, and the treated water in the digestion tank 20 is introduced into the separation membrane by the suction force of the suction pump 4 of FIG. 1. Solid materials such as sludge and suspended matter of the treated water are effectively removed by the separation membrane 30, and the liquid permeated water from which the solid substances are removed is discharged by the suction force of the suction pump 4 through the separation membrane 30. It is discharged to the water collecting tank (1) through.

Bio gas (eg, hydrogen, nitrogen, methane, carbon dioxide, etc.) separated through the fractionation tank 7 of FIG. 1 in order to prevent the substances that increase the contamination of the separator 30 from adhering to the surface of the membrane ) To be discharged to the lower part of the separation membrane, and the discharged gas shakes the separation membrane severely so that substances related to the contamination of the membrane are not easily attached to the surface of the membrane so that the effect of the separation membrane 30 is maintained for a long time. .

As a result, the apparatus of the present invention, by treating the waste water and the like containing a high concentration of organic matter in an anaerobic digestion process immersed in the separator, by using the membrane to reduce the required site area, the anaerobic bacteria in the digester By concentrating at high concentration, it produces high-efficiency digestibility and large amount of methane in a short time (within 1 day) during acid production process, and achieves the same digestibility as methane production according to digestion time of 20 days or more in a conventional digester. The membrane was configured to circulate the generated digestion gas so that the membrane is cleaned in the digester so that the durability and permeability of the membrane can be maintained. In addition, it is possible to obtain treated water containing almost no suspended solids, thus eliminating the need for additional equipment for the removal of solids.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following examples.

Example 1

Artificial synthetic wastewater using a synthetic substrate (carbohydrate concentration 10,050 mg / ℓ, COD concentration 10,650 mg / ℓ) containing glucose as a carbon source and NH ₄ HCO ₃ as a nitrogen source and a trace amount of heavy metals, etc. The hydraulic retention time (HRT) is 0.5 days, the flow rate is 3.6 L, the flux is 7.5 LMH (L / m ² · h), and the temperature is It operated under the conditions of 30 degreeC. Separation membranes immersed in the digester were used having specifications of ID / OD 0.8 / 1.4 mm, pore size 0.05 to 0.06 μm, surface area 0.01 m ² . In order to examine the role and effect of the membrane, a digester having the same substrate and the same operating conditions and no membrane was prepared and compared. As a result, the removal rate of carbohydrate was about 99.5% in the digester with the membrane and about 84% in the digester without the membrane. Mixed liquor volatile suspended solids (MLVSS), which can be expressed as microbial concentrations in the digester, were about 9,500 mg / l in the digester with a membrane and about 1,950 mg / l in the digester without a membrane. The amount of methane gas generated was about 51.3% and 0.4% in digesters with and without membranes, respectively. On the other hand, as a result of measuring the number of bacteria in the digester, acidogenic bacteria were counted as 5.1 × 10 ⁸ MPN / mL and 1.7 × 10 ⁹ MPN / mL in the digester with the membrane and the digester without the membrane, respectively. Homoacetogens were counted at 8.0 × 10 ⁵ MPN / ml and 5.0 × 10 ⁷ MPN / ml, respectively. Acetate-utilizing methanogens are about 5.1 × 10 ⁴ MPN / ml and 2.3 × 10 ⁶ MPN / ml as methane-generating bacteria, and 4.0 × 10 for H ₂ -utilizing methanogens, respectively. ³ MPN / mL and 1.3 x 10 ⁷ MPN / mL were counted. As a result, anaerobic bacteria including methane-producing bacteria were concentrated in the digester where the membrane was immersed, and organic matter was removed even in a short time of 0.5 days of HRT during acid production. Almost equal to the methane content generated over time. Therefore, when immersing the membrane in the anaerobic digestion tank, it was verified that the anaerobic bacteria were concentrated at high concentration and showed rapid digestion efficiency.

As described above, the apparatus of the present invention enables the treatment of organic materials within a short time by performing the methane fermentation process, which requires a residence time of 20 days or more, within a day, has a small construction site area, and is contaminated. Since the membrane can be automatically cleaned, it can maintain the durability and permeability of the membrane, and since the discharged water does not contain any solids, it is effective because no additional device for removing the solids is required.

Claims (7)

In the anaerobic digestion wastewater treatment apparatus, Digester for storing waste and waste water, A separation membrane immersed in the digester and formed to filter sludge and suspended solids contained in the wastewater and wastewater in the digester; One end is connected to communicate with the inside of the separation membrane, the other end and the permeate discharge pipe connected to the collecting tank is installed separately, A pressure gauge installed on a line of the permeate discharge pipe and measuring a contamination state of the separator, and a suction pump for transferring the liquid permeate filtered from the separator to a collection tank; A mixture discharge pipe having one end disposed on an upper surface of the waste and waste water stored in the digester and connected to a fractionation tank having a separate discharge pipe; One end is connected to the fractionation tank, the other end is connected to the digester and the gas supply pipe located in the lower membrane; Immersion type membrane separation anaerobic digestion wastewater treatment apparatus is installed on the gas supply pipe and comprises a vacuum pump for vibrating the separation membrane by transferring the gas in the separation tank to the lower portion of the separation membrane. 2. The substrate tank of claim 1, further comprising: a substrate tank provided separately from the digester and used as a nutrient source for microorganisms for purifying wastewater and wastewater; A supply pipe connecting the digester and the substrate tank to communicate with each other; Submerged membrane separation anaerobic digestion wastewater treatment apparatus is installed on the supply pipe comprises a substrate supply means consisting of a pump for supplying the substrate in the substrate tank to the digester. The immersion type membrane separation anaerobic digestion wastewater treatment apparatus according to claim 1, wherein the amount of gas supplied by the vacuum pump installed on the gas supply pipe is adjusted according to the degree of contamination of the separation membrane read by the pressure gauge. The immersion type membrane separation anaerobic digestion wastewater treatment apparatus according to claim 1, further comprising a gas measuring sensor installed at one side of the digester to measure a component of gas generated in the digester. The immersion type membrane separation anaerobic digestion wastewater treatment apparatus according to claim 1, further comprising a water level control sensor installed at an upper side of the digester to sense the water level in the digester. The immersion type membrane separation anaerobic digestion wastewater treatment apparatus according to claim 1, wherein the separation membrane is a flat membrane and a hollow fiber membrane. The immersion type membrane separation anaerobic digestion wastewater treatment apparatus according to claim 1, wherein the separation membrane is continuously cleaned by shaking of the separation membrane by the gas generated at the gas outlet installed at the bottom of the separation membrane.