JP2018153731A - Aerobic biological treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aerobic biological treatment apparatus which can apply aerobic biological treatment to even an organic waste water including volatile substance or odor generating substance without odor generation or harmful substance volatilization.SOLUTION: The aerobic biological treatment apparatus is provided which comprises a first reaction tank 3 and a second reaction tank 12 connected in series and in which each of the reaction tank 3,12 performs aerobic biological treatment. In the aerobic biological treatment apparatus, the first reaction tank 3 is an MABR (Membrane Aeration Bio Reactor) reaction tank for dissolving oxygen in a water to be treated through an oxygen dissolving membrane module 2 disposed within the reaction tank 3, and the second reaction tank 12 is a reaction tank other than the MABR.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an aerobic biological treatment apparatus suitable for anaerobic biological treatment of organic wastewater containing volatile substances and substances that generate odors, and in particular, water to be treated in a reaction tank using an oxygen-dissolving membrane. The present invention relates to an aerobic biological treatment apparatus that employs a MABR (membrane aeration bioreactor) system in which oxygen is dissolved in the water.

  When organic wastewater containing generated volatile substances or odorous substances is biologically treated, a fully mixed reaction tank is usually used to prevent odors. However, since the reaction rate becomes extremely small in a completely mixed reaction tank, a large reaction tank with a long residence time is required. In addition, it is difficult to completely prevent odorous substances from volatilizing even in a completely mixed reaction tank due to a single flow of water or a difference in partial aeration intensity.

  In order to increase the reaction rate and reduce the tank volume, a multistage reaction tank in which a plurality of reaction tanks are connected in series is used. However, in this case, since the decomposition of the odorous substance is not completed in the first reaction tank, a part of the remaining odorous substance is volatilized by aeration, and the odor is generated or the toxic substance is volatilized. . The same applies to a plug flow type reaction vessel.

  In the aerobic biological treatment apparatus using the MABR method, the aerobic biological treatment is performed by dissolving oxygen in the water to be treated by the oxygen-dissolving film. As an oxygen-dissolving membrane, a hollow fiber membrane is often used as in Patent Document 1.

Japanese Patent No. 4907922

  The present invention provides an aerobic biological treatment apparatus capable of performing an aerobic biological treatment without generation of odor or volatilization of harmful substances even with organic wastewater containing volatile substances or substances that generate odors. With the goal.

  The gist of the present invention is as follows.

[1] In an aerobic biological treatment apparatus that includes first to n-th (n is 2 or more) reaction tanks connected in series and performs aerobic biological treatment in each reaction tank, at least the first reaction tank includes: An aerobic biological treatment apparatus, which is a MABR reaction tank in which oxygen is dissolved in water to be treated by an oxygen dissolving film disposed in the reaction tank, and at least the final reaction tank is a reaction tank other than MABR.

[2] The aerobic biological treatment apparatus according to [1], wherein the reaction tank other than the MABR is a sludge floating reaction tank or a carrier flow reaction tank.

[3] In the aerobic biological treatment apparatus that performs the aerobic biological treatment in the reaction tank, the reaction tank is a plug flow reaction tank, and the treated water inflow side in the reaction tank is supplied with oxygen by an oxygen-dissolving film. An aerobic biological treatment apparatus characterized in that it is a MABR system that dissolves in water to be treated in a reaction tank, and the treated water outlet side of the reaction tank is a treatment system other than MABR.
[4] The aerobic biological treatment apparatus according to [3], wherein the treated water outlet side of the reaction tank is a sludge floating reaction method or a carrier flow reaction method.

  Since MABR can dissolve oxygen without generating bubbles, volatile substances from the reaction tank are not diffused into the exhaust gas. However, since MABR is not suitable for removing very low concentration BOD, installing MABR in the final tank of a multistage reaction tank requires a large reaction tank, which is disadvantageous in terms of space and cost. Considering these points, the first half of the multistage reaction tank where the decomposition of volatile substances and odor-causing substances is completed, or the reaction tank excluding the final stage is designated as MABR, and the BOD removal tank at the final tank finish is a biological organism other than MABR. By performing the treatment, an efficient biological treatment without generation of odor and volatilization of volatile substances becomes possible. The same applies to the case where the first half of the plug flow reaction tank is a MABR and the second half is a biological treatment other than MABR.

It is a typical longitudinal cross-sectional view of the aerobic biological treatment apparatus of this invention. It is a block diagram of the biological activated carbon processing apparatus used by embodiment. It is a longitudinal cross-sectional view of the biological activated carbon processing apparatus used by embodiment. It is a longitudinal cross-sectional view of the biological activated carbon processing apparatus used by embodiment. It is a longitudinal cross-sectional view of the biological activated carbon processing apparatus used by embodiment. It is a longitudinal cross-sectional view of the biological activated carbon processing apparatus used by embodiment. (A) is a side view of an oxygen supply permeable membrane module, (b) is a perspective view of an oxygen supply permeable membrane module. It is a front view of a hollow fiber membrane module. It is a perspective view explaining the arrangement | sequence of a hollow fiber membrane. (A) is a front view which shows the arrangement | sequence of the hollow fiber membrane in a hollow fiber membrane module, (b) is the side view. It is a perspective view of a hollow fiber membrane module.

  The apparatus of the present invention is a substance that generates odors, for example, volatile malodorous substances (22 substances designated by the malodorous prevention method such as ammonia and hydrogen sulfide, etc. discharged from waste disposal plants, sewage treatment plants, and pulp manufacturing plants: “ 4th edition Handbook Odor Prevention Law (August 2001, edited by Odor Law Study Group, published by Gyosei) ”, volatile poisons (vinyl chloride, trichlorethylene, etc.) discharged from vinyl chloride resin manufacturing factories, semiconductor factories It is suitable for treating organic wastewater containing malodorous substances such as methyl sulfide and methyl mercaptan generated in the DMSO decomposition process discharged from the waste water.

  In one embodiment of the present invention, at least the first tank of the multistage reaction tank is a MABR tank, and at least the final reaction tank is a reaction tank other than MABR. When the reaction tank has three or more stages, it is preferable that at least the first tank and the second tank be MABR, and the final tank be a treatment other than MABR, for example, a floating method, a carrier fluidized bed, or the like. As a specific example of the reaction tank of the carrier fluidized bed, there may be mentioned one in which a carrier such as sponge is introduced so as to have a volume of 30 to 50%, and a screen for preventing the carrier such as sponge is provided in the outflow part of the reaction tank.

When all or most of the organic substances are volatile substances, it is desirable that all reaction vessels other than the final reaction vessel be MABR reaction vessels.

  When the proportion of the volatile component in the organic substance is small, it is desirable that about 1/2 of the first half side should be other than MABR and about 1/2 of the second half side should be other than MABR. For example, in the case of 4 tanks as a whole, it is desirable that the 2 tanks on the first half side be MABR and the 2 tanks on the second half side be other than MABR.

  The MABR treatment is effective when the pre-stage reaction tank is heavily loaded. Biofilm formation does not progress in the reaction tank on the downstream side where the processing is progressing and the load is low, so it is more effective to use a carrier method such as a floating method with high contact efficiency with aeration or a fluidized bed. is there.

  In the case of a plug flow type reaction vessel, if the ratio of the width and the length of the reaction vessel is usually 1:20 or more, plug flow is obtained. In general, the plug flow type reaction tank is not straight in the length direction, and is often folded back so as to reciprocate 3 or 5 times. Waste water flows in from one end and treated water flows out from the other end. In the same manner as in the multistage reaction tank, MABR is used for the drainage inflow side and another treatment system is used for the outflow part. As another treatment method, a carrier fluidized bed in which a sponge is introduced so as to have a volume of 30 to 50% and a screen for preventing sponge outflow is provided in the treated water outflow portion as described above.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of an aerobic biological treatment apparatus 1 according to an example of the present invention. An oxygen-dissolving membrane module 2 is installed in the first reaction tank 3. One or a plurality of oxygen-dissolving membrane modules 2 are installed. The oxygen-dissolving membrane module 2 may be installed in multiple upper and lower stages.

  The raw water is supplied to the reaction tank 3 through the pipe 4, and the treated water flows over the trough 6 and flows out from the outlet 7.

  The oxygen-dissolving membrane module 2 includes a non-porous oxygen-dissolving membrane, and oxygen that has permeated the membrane is dissolved in the water to be treated in the reaction tank 3, so that no bubbles are generated in the reaction tank 3.

  Air from the blower B is supplied to the oxygen-dissolving membrane module 2 through the pipe 8, and the exhaust gas flowing out from the oxygen-dissolving membrane module 2 is discharged through the pipe 9. Air may flow from the top to the bottom of the oxygen-dissolving membrane module 2, may flow from the bottom to the top, or may flow in the lateral direction. When a plurality of oxygen-dissolving membranes are ventilated, they may be ventilated in series or in parallel.

  A diffuser pipe 5 is installed below the oxygen-dissolved membrane module 2, air is intermittently supplied via the pipe 10, and the inside of the reaction tank 3 is aerated.

  The 1st treated water from the outflow port 7 is introduce | transduced into the 2nd reaction tank 12 which performs aerobic biological treatment other than MABR, is further aerobically treated, and turns into 2nd treated water. This second treated water is introduced into the solid-liquid separator 13 and separated into solid and liquid, and then taken out as final treated water. Part of the separated sludge is returned to the reaction tank 3 (or the reaction tanks 3 and 12) via the return pipe 13a.

  In the present invention, the reaction tank may be a biological activated carbon reaction tank. FIG. 2A is a longitudinal sectional view showing an example of a biological activated carbon treatment reaction tank, and FIG. 2B is a perspective view of the nozzle. A plurality of oxygen permeable membrane modules 2 are installed in the reaction tank 3 in multiple upper and lower stages. In this embodiment, the oxygen permeable membrane module 2 is installed in three stages, but the oxygen permeable membrane module 2 is preferably installed in two to eight stages, particularly 2 to 4 stages.

  The raw water is supplied to the bottom of the reaction tank 3 by the piping 14 and the plurality of nozzles 14a to form a fluidized bed F of activated carbon. The treated water that has passed through the fluidized bed F overflows the trough 6 and flows out from the outlet 7.

  The oxygen permeable membrane module 2 includes a non-porous oxygen permeable membrane, and oxygen that has permeated through the membrane is dissolved in the water to be treated in the reaction tank 3, so that no bubbles are generated in the reaction tank 3.

  In FIG. 2, oxygen-containing gas such as air from the blower B is supplied to the upper part of the lowermost oxygen permeable membrane module 2 c through the pipe 8, flows out from the lower part of the oxygen permeable membrane module 2 c, and passes through the pipe 19. To the upper part of the oxygen permeable membrane module 2b in the second stage, flows out from the lower part of the oxygen permeable membrane module 2b, and is supplied to the upper part of the uppermost oxygen permeable membrane module 2a through the pipe 20. The gas flowing out from the lower part of the oxygen permeable membrane module 2b is discharged through the pipe 21.

  It is preferable that the oxygen permeable membrane module 2 exists over substantially the entire area of the activated carbon fluidized bed F in the vertical direction. Moreover, it is preferable that the oxygen permeable membrane module 2 is arranged evenly in the whole area in the reaction tank 3 in the plan view of the reaction tank 3.

  In FIG. 2, raw water is discharged from the plurality of nozzles 14 a to the bottom of the reaction tank 3. As shown in FIG. 3, a water permeable plate 22 such as a punching metal is disposed at the bottom of the reaction tank 3. You may form the large diameter particle layer 23, such as coarse gravel, on the upper side of the board 22, and the small diameter particle layer 24, such as fine gravel on the upper side. The raw water flows out from the pipe 14 into the receiving chamber 25 below the water permeable plate 22 through the nozzle 26, passes through the water permeable plate 22, the large particle layer 23, and the small particle layer 24, and into the reaction tank 3 is a fluidized bed of activated carbon. F is formed. Note that a water-permeable plate such as punching metal is not necessary.

  Next, another example of the flow mode of the oxygen-containing gas to the oxygen permeable membrane module 2 will be described with reference to FIGS.

  In the biological treatment apparatus of FIG. 4, the oxygen-containing gas from the blower B is supplied to the upper part of the lowermost oxygen permeable membrane module 2c through the pipe 8, flows out from the lower part, and the second stage oxygen from the lower part. It is supplied to the lower part of the permeable membrane module 2b, flows out from the upper part thereof, is then supplied to the lower part of the uppermost oxygen permeable membrane module 2a, and is discharged from the upper part through the pipe 21.

  In the biological treatment apparatus of FIG. 5, the oxygen-containing gas from the blower B is supplied to the lower part of the lowermost oxygen permeable membrane module 2c through the pipe 8, flows out from the upper part, and the second stage oxygen from the lower part. It is supplied to the lower part of the permeable membrane module 2b, flows out from the upper part thereof, is then supplied to the lower part of the uppermost oxygen permeable membrane module 2a, and is discharged from the upper part through the pipe 21.

  In the biological treatment apparatus of FIG. 6, the oxygen-containing gas flows in parallel to the oxygen permeable membrane modules 2a to 2c. That is, the oxygen-containing gas from the blower B is supplied to the upper part of each oxygen permeable membrane module 2 a, 2 b, 2 c through the pipe 8, flows out from the lower part of each, and is discharged through the pipe 21.

  2-4, the oxygen-containing gas is supplied to the upper part of the lowermost oxygen permeable membrane module 2c, flows out from the lower part of the oxygen permeable membrane module 2c, and then the upper oxygen permeable membrane module 2b, In the biological treatment apparatus configured to flow sequentially to 2a, the condensed water in the oxygen permeable membrane module 2c is likely to escape.

  As shown in FIG. 5, when the oxygen-containing gas is configured to flow upward in the oxygen permeable membrane modules 2a to 2c, the condensed water in the oxygen permeable membrane module easily evaporates. In particular, by flowing a gas with high dryness as the oxygen-containing gas, the condensed water is easily evaporated.

  As shown in FIGS. 2 to 5, in the biological treatment apparatus in which the oxygen-containing gas is circulated sequentially from the lowermost oxygen permeable membrane module 2 c to the upper oxygen permeable membrane modules 2 b and 2 a, Since the flow of the treated water is an upward flow, more oxygen is supplied to the water to be treated on the raw water side having a higher BOD concentration, so that the oxygen supply amount according to the load can be obtained.

  As shown in FIG. 6, when the oxygen-containing gas is circulated in parallel to each of the oxygen permeable membrane modules 2a to 2c, the pressure loss of the oxygen-containing gas is small and energy is saved. In FIG. 6, the oxygen supply amount according to the load can be obtained by increasing the oxygen-containing gas flow rate in the lower oxygen permeable membrane module.

  In any of FIGS. 2 to 6, the oxygen permeable membrane module on the upper side may have a smaller membrane area or a lower membrane packing density.

  4-6, it is good also as a bottom part structure which has the water-permeable board 22, the large diameter particle layer 23, and the small diameter particle layer 24 like FIG.

  The oxygen permeable membrane of the oxygen permeable membrane module 2 may be any of a hollow fiber membrane, a flat membrane, and a spiral membrane, but a hollow fiber membrane is preferable. As the material of the film, silicon, polyethylene, polyimide, polyurethane and the like which are usually used for MABR can be used, but silicon is preferable. A composite film having a high strength and a porous hollow fiber coated with a nonporous polymer may be used.

  The hollow fiber membrane preferably has an inner diameter of 0.05 to 4 mm, particularly 0.2 to 1 mm, and a thickness of 0.01 to 0.2 mm, particularly 0.02 to 0.1 mm. If the inner diameter is smaller than this, the aeration pressure loss is large, and if it is larger, the surface area becomes smaller and the oxygen dissolution rate decreases. When the thickness is smaller than the above range, the physical strength is reduced and the film is easily broken. On the other hand, when the thickness is larger than the above range, the oxygen permeation resistance increases and the oxygen dissolution efficiency decreases.

  The length of the hollow fiber membrane is preferably about 0.5 to 3 m, particularly preferably about 1 to 2 m. If the hollow fiber membrane is too long, when a large amount of biofilm adheres, problems such as breakage, solidification into a dumpling, a decrease in surface area, a decrease in oxygen dissolution efficiency, and an increase in pressure loss occur. If the hollow fiber membrane is too short, the cost increases. For the same reason, the length of the flat membrane and the spiral membrane is preferably 0.5 to 1.5 m.

The required area of the membrane is sufficient to supply the amount of oxygen necessary for processing. For example, when the raw water is CODcr 50 mg / L and the residence time is 30 minutes, a hollow fiber membrane made of silicon having a thickness of 100 μm requires 240 m ² or more per 1 m ³ of the volume of the activated carbon part flowing.

The area of the membrane is preferably 300 m ² or more and 1000 m ² / m ³ or less per tank volume. If the membrane area is large, the amount of oxygen supply increases and a high load is possible, but the membrane cost increases. If the membrane area per unit volume is too large, the membrane will be in a dumpling state and efficiency will be reduced. The membrane is preferably installed in the flow direction. For example, in a tank with a water depth of 10 m, it is preferable to install a 2 m long membrane in four stages up and down.

  Next, an example of the structure of the oxygen permeable membrane module will be described with reference to FIGS.

  The oxygen permeable membrane module 30 in FIG. 7 uses a hollow fiber membrane 27 as an oxygen permeable membrane. In this embodiment, the hollow fiber membranes 27 are arranged in the vertical direction, and the upper end of each hollow fiber membrane 27 is connected to the upper header 28 and the lower end is connected to the lower header 29. The inside of the hollow fiber membrane 27 communicates with the upper header 28 and the lower header 29, respectively. Each header 28, 29 is a hollow tube, and a plurality of headers 28, 29 are arranged in parallel in a substantially horizontal direction. Even when a flat film or a spiral film is used, they are arranged in the vertical direction.

  One end or both ends of each header 28 are preferably connected to the manifold 28A, and one end or both ends of each header 29 are preferably connected to the manifold 29A. When oxygen-containing gas is supplied to the upper part of the oxygen permeable membrane module 30 and discharged from the lower part of the oxygen permeable membrane module 30, the oxygen-containing gas flows from the upper header 28 through the hollow fiber membrane 27 to the lower header 29, Oxygen permeates through the hollow fiber membrane 27 and dissolves in the water in the reaction vessel 3. Conversely, when oxygen-containing gas is supplied to the lower part of the oxygen permeable membrane module 30 and discharged from the upper part, the oxygen-containing gas is supplied to the lower header 29 and is discharged from the upper header 28 through the hollow fiber membrane 27. .

  FIG. 8 is a front view showing an example of the oxygen permeable membrane module 30 disposed in the frame 32. The frame 32 has four pillars 32a erected at the four corners, an upper beam 32b erected between the upper ends of the pillars 32a, and a lower erection between lower parts of the pillars 32a. It has the beam 32c and the base plate 32d attached to the lower end surface of each pillar 32a. By holding the manifolds 28 </ b> A and 29 </ b> A of the oxygen permeable membrane module 30 in the frame 32, the oxygen permeable membrane module 30 is installed in the frame 32.

  The oxygen permeable membrane module 30 provided with the frame 32 can be easily installed in the reaction tank 3 in multiple upper and lower stages. That is, the upper oxygen permeable membrane module 30 can be disposed on the frame 32 of the lower oxygen permeable membrane module 30 so that the bottom seat plate 32d of the upper oxygen permeable membrane module 30 is placed thereon.

  In one aspect of the present invention, a hollow fiber membrane module in which hollow fiber membranes are arranged in the vertical direction is a membrane module having a low height of about 1 to 2 m, and is laminated in two or more stages, preferably four or more stages. To do.

  In this way, oxygen can be dissolved at a low pressure by stacking hollow fiber membrane modules in which the length of the hollow fiber membrane is shortened and the height is lowered in multiple stages.

  The pressure of the oxygen-containing gas blown to the hollow fiber membrane is preferably a pressure slightly higher than the pressure loss of the hollow fiber membrane, for example, about 5 to 20% higher from the viewpoint of cost.

  The pressure supplied to the hollow fiber membrane may be determined regardless of the water depth. Since a normal air diffuser requires a pressure higher than the water depth, the present invention is more advantageous as the water depth of the reaction vessel is deeper.

  In addition, the influence of the carbon dioxide gas melt | dissolved in a film | membrane from the condensed water in a film | membrane or a biological tank changes with piping connection of the module of an up-down direction. Therefore, it is preferable to adopt a pipe connection structure that takes pressure loss, condensed water, and carbon dioxide into consideration.

  In the above embodiment, as shown in FIGS. 7 and 8, the hollow fiber membrane 27 is in the vertical direction, and the raw water (treated water) flows in the vertical direction along the hollow fiber membrane 27. As the oxygen permeable membrane module, an oxygen permeable membrane module having a horizontal X-direction hollow fiber membrane 27b and a vertical (Z-direction) hollow fiber membrane 27a as shown in FIG. 9 may be used. As shown in FIG. 10, the hollow fiber membranes 27a and 27b may be braided into a plain weave.

  FIG. 11 is a perspective view showing an example of an oxygen permeable membrane module provided with such hollow fiber membranes 27 (27a, 27b) in the X and Z directions. The oxygen permeable membrane module 40 includes a pair of parallel headers 41, 41 extending in the Z direction, a pair of headers 42, 42 extending in the X direction orthogonal to the header 41, 41, and the hollow fiber membrane 27. Have. The hollow fiber membrane 27 in the X direction is constructed between the headers 41 and 41, and the hollow fiber membrane 27 in the Z direction is constructed between the headers 42 and 42.

  By connecting the end portions of the headers 41 and 42 to each other, the headers 41 and 42 have a rectangular frame shape. In one embodiment of the oxygen permeable membrane module 40, closing members (not shown) such as end plugs are provided inside both ends of the headers 41 and 42, and the headers 41 and 42 are blocked. The oxygen-containing gas is supplied to one header 41, passes through the hollow fiber membrane 27, and flows into the other header 41. The oxygen-containing gas is supplied to one header 42, passes through the hollow fiber membrane 27, and flows into the other header 42.

  In another aspect of the oxygen permeable membrane module 40, one one header 41 and one one header 42 communicate with each other. The other one header 41 and the other one header 42 communicate with each other. A closing member (not shown) such as an end plug is provided inside the connecting portion of the one header 41, 42 and the other header 41, 42, and the one header 41, 42 and the other header 41, 42 are connected to each other. The headers 41 and 42 are blocked. The oxygen-containing gas is supplied to the one header 41, 42, passes through the hollow fiber membrane 27, and flows into the other header 41, 42.

  In addition, although these hollow fiber membranes are one by one in FIGS. 7 to 11, a bundle of several to 100 may be used.

  In addition, you may install an aeration apparatus in the lower part in a reaction tank.

  Next, preferred examples of biological carrier, oxygen-containing gas, and other processing conditions will be described.

<Biological carrier>
Activated carbon is suitable as the biological carrier.

  The filling amount of the activated carbon is preferably about 40 to 60%, particularly about 50% of the volume of the reaction vessel. The larger the filling amount, the greater the amount of biomass and the higher the activity. Therefore, it is preferable to pass water through an LV in which the activated carbon phase expands by about 20 to 50% when the filling amount is about 50%. The water flow LV is 0.5 mm activated carbon and is about 7 to 15 m / hr. Gels other than activated carbon, porous materials, non-porous materials, and the like can be used under similar conditions. For example, polyvinyl alcohol gel, polyacrylamide gel, polyurethane foam, calcium alginate gel, zeolite, plastic and the like can also be used. However, when activated carbon is used as the carrier, it is possible to remove a wide range of pollutants by the interaction between the activated carbon adsorption and biodegradation.

  The average particle size of the activated carbon is preferably about 0.2 to 3 mm. When the average particle size is large, it is possible to achieve a high LV, and the amount of circulation can be increased, so that a high load is possible. However, because the surface area is small, the biomass is reduced. If the average particle size is small, the pump power can be reduced because it can flow at a low LV. And since the surface area is large, the amount of attached organisms increases.

  The optimum particle size is determined by the concentration of wastewater, and is preferably about 0.2 to 0.4 mm when TOC is 50 mg / L, and about 0.6 to 1.2 mm when TOC is 10 mg / L.

  The expansion ratio of the activated carbon is preferably about 20 to 50%. If the expansion rate is lower than 20%, there is a possibility of clogging and short circuit. If the expansion rate is higher than 50%, there is a risk of outflow and the pump power cost becomes high.

  In normal biological activated carbon, the activated carbon fluidized bed has an expansion rate of about 10 to 20%. As a result, the membrane installed at the same time is rubbed by activated carbon and worn out. In order to prevent this, in the present invention, the activated carbon needs to flow sufficiently, and the expansion rate is desirably 20% or more. For this reason, the particle size of the activated carbon is preferably smaller than that of normal biological activated carbon. The activated carbon may be anything from coconut charcoal, coal, charcoal and the like. The shape is preferably spherical charcoal, but may be ordinary granular charcoal or crushed charcoal.

<Oxygen-containing gas>
The oxygen-containing gas may be a gas containing oxygen, such as air, oxygen-enriched air, or pure oxygen. It is desirable that the gas to be vented pass through a filter to remove fine particles.

  The amount of aeration is preferably about twice the amount of oxygen required for biological reactions. If it is less than this, BOD and ammonia will remain in the treated water due to insufficient oxygen, and if it is greater, the air flow will be unnecessarily increased and the pressure loss will be increased, so the economy will be impaired.

  The aeration pressure is desirably slightly higher than the pressure loss of the hollow fiber generated at a predetermined aeration amount.

<Flow rate of treated water>
It is preferable that the flow rate of the water to be treated is LV10 m / hr or more, and the treatment water is not circulated and treated in one pass.

When the LV is increased, the oxygen dissolution rate is proportionally increased. At LV 50 m / hr, oxygen dissolves about twice as much as 10 m / hr. When LV is high, it is preferable to use activated carbon having a large particle size so that the expansion rate is not so large. The optimal LV range is about 10 to 30 m / hr from the biomass and oxygen dissolution rate.

<Residence time>
It is preferable to set the residence time such that the tank load is 1 to 2 kg-TOC / m ³ / day.

<Blower>
As the blower, it is sufficient that the discharge wind pressure is equal to or lower than the water pressure coming from the water depth. However, it is necessary to be more than the pressure loss of piping. Usually, the pipe resistance is about 1 to 2 kPa.

  In the case of a water depth of 5 m, a general-purpose blower with an output of up to about 0.55 MPa is usually used, and a high-pressure blower has been used at a water depth higher than that.

  In the present invention, a general purpose blower having a pressure of 0.5 MPa or less can be used even at a water depth of 5 m or more, and a low pressure blower of 0.1 MPa or less is preferably used.

  The supply pressure of the oxygen-containing gas is required to be higher than the pressure loss of the hollow fiber membrane, lower than the water depth pressure, and further, the membrane should not be crushed by water pressure. Since the pressure loss of the flat membrane and the spiral membrane is negligible compared to the water pressure, the pressure is very low, about 5 kPa or more, water pressure or less, preferably 20 kPa or less.

In the case of a hollow fiber membrane, the pressure loss varies depending on the inner diameter and length. Since the amount of air to be vented is ²⁰ mL to 100 mL / day per 1 m ² of membrane, the amount of air doubles when the membrane length is doubled, and the amount of air is only doubled even when the membrane diameter is doubled. Don't be. Therefore, the pressure loss of the membrane is directly proportional to the membrane length and inversely proportional to the diameter.

  The value of pressure loss is about 3 to 20 kPa for hollow fibers having an inner diameter of 50 μm and a length of 2 m.

  According to the experiment of the present inventor, it was confirmed that the oxygen dissolution rate hardly changed as a result of changing the aeration pressure to 11 to 140 kPa and the aeration amount to 240 to 460 mL / min.

  In the present invention, the oxygen dissolution efficiency is preferably 30 to 100%, particularly 40 to 60%.

  Although the fluidized bed F of the carrier is formed in FIGS. 2 to 6, the carrier may be suspended. The carrier is preferably suspended or fluidized by one or more of aeration of the liquid in the reaction vessel, flow of the liquid, and mechanical operation.

  By suspending or flowing the carrier in this manner, it is possible to prevent organisms from adhering to the oxygen-dissolving film and to keep the oxygen supply rate from the oxygen-dissolving film high.

  By maintaining the MLSS concentration in the reaction tank at a high concentration, it is possible to prevent the organism from attaching to the oxygen-dissolved membrane. The MLSS concentration is preferably maintained at 10,000 to 50,000 mg / L, particularly preferably 20,000 to 30,000 mg / L.

  In order to maintain MLSS at a high concentration, it is preferable to install a filtration membrane in the treatment liquid in the reaction tank and take out the permeated water of this filtration membrane as the treatment water.

[Example 1]
Semiconductor cleaning wastewater containing DMSO 3.2% was passed through with a TOC tank load of 1.2 kg / m ³ / D, a water tank capacity of 10 L, and a residence time of 24 hours.

  Odor (DMS) measurement was carried out 10 days, 20 days and 21 days after water flow. In any measurement, it was below the DMS lower limit (0.25 mg / L) of the detection tube. In addition, by performing biological treatment (standard activated sludge treatment method) at the subsequent stage, it was possible to further reduce low-load organic matter. The odor measurement was performed using a gas tube pyrotube detector tube.

[Comparative Examples 1 and 2]
In an in-line three-stage biological treatment tank in a semiconductor manufacturing plant, an average of DMS is 2.73 ppm (MIN: MIN :) in the air around the feed with an average TOC delivery of 0.17 kg / m ³ / D (DMSO content ratio of about 2%). 0 ppm to MAX 25.5 ppm) (Comparative Example 1). In addition, the average DMS was detected at 9.84 ppm (MIN: 0 ppm to MAX 59 ppm) in the air around the feeding by the operation of TOC sending average 0.24 kg / m ³ / D (DMSO content ratio about 2%) (Comparative Example) 2).

DESCRIPTION OF SYMBOLS 1 Aerobic biological treatment apparatus 2 Oxygen dissolution membrane module 3 1st reaction tank 12 2nd reaction tank

The present invention relates to an aerobic biological treatment apparatus suitable for treating an organic wastewater containing a volatile substance or an odorous substance, and in particular, to-be-treated water in a reaction tank using an oxygen permeable membrane. The present invention relates to an aerobic biological treatment apparatus that employs a MABR (membrane aeration bioreactor) system in which oxygen is dissolved in the water.

In the aerobic biological treatment apparatus using the MABR method, oxygen is dissolved in the water to be treated by the oxygen permeable membrane to perform the aerobic biological treatment. As an oxygen permeable membrane , a hollow fiber membrane is often used as in Patent Document 1.

[1] In an aerobic biological treatment apparatus that includes first to n-th (n is 2 or more) reaction tanks connected in series and performs aerobic biological treatment in each reaction tank, at least the first reaction tank includes: A MABR reaction tank which is disposed in the reaction tank and dissolves oxygen in the water to be treated by a non-porous oxygen permeable membrane , and the water to be treated is an organic waste water containing a volatile substance or a substance generating odor. And at least the final reaction tank is a reaction tank other than MABR.

[3] In the aerobic biological treatment apparatus that performs aerobic biological treatment in the reaction tank, the reaction tank is a plug flow reaction tank, and the treated water inflow side in the reaction tank is formed by a non-porous oxygen permeable membrane . It is a MABR system in which oxygen is dissolved in the water to be treated in the reaction tank, and the water to be treated is an organic waste water containing a volatile substance or a substance generating odor, and the treated water in the reaction tank An aerobic biological treatment apparatus characterized in that the outlet side has a treatment method other than MABR.
[4] The aerobic biological treatment apparatus according to [3], wherein the treated water outlet side of the reaction tank is a sludge floating reaction method or a carrier flow reaction method.
[5] In any one of [1] to [4], the oxygen permeable membrane is a hollow fiber membrane through which an oxygen-containing gas is blown, and the blowing pressure of the oxygen-containing gas is a pressure loss of the hollow fiber membrane. An aerobic biological treatment apparatus characterized in that the pressure is 5 to 20% higher.

Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of an aerobic biological treatment apparatus 1 according to an example of the present invention. An oxygen permeable membrane module 2 is installed in the first reaction tank 3. One or a plurality of oxygen permeable membrane modules 2 are installed. The oxygen permeable membrane module 2 may be installed in upper and lower stages.

The oxygen permeable membrane module 2 includes a non-porous oxygen permeable membrane, and oxygen that has permeated through the membrane is dissolved in the water to be treated in the reaction tank 3, so that no bubbles are generated in the reaction tank 3.

The air from the blower B is supplied to the oxygen permeable membrane module 2 through the pipe 8, and the exhaust gas flowing out from the oxygen permeable membrane module 2 is discharged through the pipe 9. The air may flow from the top to the bottom of the oxygen permeable membrane module 2, may flow from the bottom to the top, or may flow in the lateral direction. When ventilating a plurality of oxygen permeable membranes , they may be ventilated in series or in parallel.

A diffuser pipe 5 is installed below the oxygen permeable membrane module 2, air is intermittently supplied via the pipe 10, and the inside of the reaction tank 3 is aerated.

By thus suspended or fluidized carrier, it is possible to prevent biofouling of the oxygen-permeable membrane, it is possible to maintain a high oxygen supply speed from the oxygen-permeable membrane.

By maintaining the MLSS concentration in the reaction tank at a high concentration, it is possible to prevent the organism from attaching to the oxygen permeable membrane . The MLSS concentration is preferably maintained at 10,000 to 50,000 mg / L, particularly preferably 20,000 to 30,000 mg / L.

[Comparative Examples 1 and 2]
In an in-series three-stage biological treatment tank of a semiconductor manufacturing plant, an average DMS of 2.73 ppm (MIN: MIN :) in the air around the apparatus with an average TOC tank load of 0.17 kg / m ³ / D (DMSO content ratio of about 2%) 0 ppm to MAX 25.5 ppm) (Comparative Example 1). In addition, an average of 9.84 ppm (MIN: 0 ppm to MAX 59 ppm) of DMS was detected in the air around the apparatus during operation with an average TOC tank load of 0.24 kg / m ³ / D (DMSO content ratio of about 2%) (Comparative Example) 2).

DESCRIPTION OF SYMBOLS 1 Aerobic biological treatment apparatus 2 Oxygen permeable membrane module 3 1st reaction tank 12 2nd reaction tank

Claims (4)

In an aerobic biological treatment apparatus comprising first to n-th (n is 2 or more) reaction tanks connected in series and performing an aerobic biological treatment in each reaction tank,
At least the first reaction tank is a MABR reaction tank in which oxygen is dissolved in the water to be treated by an oxygen dissolving film disposed in the reaction tank, and at least the final reaction tank is a reaction tank other than MABR. Temper biological treatment equipment.   2. The aerobic biological treatment apparatus according to claim 1, wherein the reaction tank other than the MABR is a sludge floating reaction tank or a carrier flow reaction tank. In an aerobic biological treatment apparatus that performs aerobic biological treatment in a reaction tank,
The reaction tank is a plug flow reaction tank, and the treated water inflow side in the reaction tank is a MABR system in which oxygen is dissolved in the treated water in the reaction tank by an oxygen dissolving film.
An aerobic biological treatment apparatus characterized in that the treatment water outlet side of the reaction tank has a treatment method other than MABR.   4. The aerobic biological treatment apparatus according to claim 3, wherein the treated water outlet side of the reaction tank is a sludge floating reaction method or a carrier flow reaction method.

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