KR20040020807A - Apparatus and method for reducing sludge volume, apparatus and method for treating wastewater using the same - Google Patents

Abstract

PURPOSE: A method and an apparatus for reducing the volume of sludge for efficiently reducing the volume of biological sludge and suppressing the increase of energy consumption are provided, and a method and an apparatus for treating wastewater using the method and the apparatus for reducing the volume of sludge are provided. CONSTITUTION: The apparatus(310) for reducing the volume of the sludge comprises a cylindrical vessel(31) as a sludge treating section to which liquid(W') to be treated is supplied and in which perforated plate groups(33) connected to a shaft(34) and having a plurality of openings are coaxially provided; and a circulation line(L50) to which the vessel is connected, and along which a pump(P3) is arranged through three-way valves(V33,V34), wherein the apparatus forcibly circulates a multiphase flow of the liquid and air etc., by aerating the liquid with the air etc., from a gas supply source(11) while supplying the liquid to the vessel and by operating the pump, and wherein the flow directions of multiphase flow are occasionally switched to arrows X and Y directions by adjusting opening and closing of each of the valves.

Description

Apparatus and method for reducing sludge volume, apparatus and method for treating wastewater using the same}

The present invention relates to a sludge perception device, a sludge perception method, a wastewater treatment device using the same, and a wastewater treatment method for biological treatment of organic wastewater and the like.

Conventionally, the activated sludge method is used as a typical method for the treatment of organic wastewater (drainage, sewage) such as sewage and industrial wastewater. In biological treatment using such a method, a large amount of surplus sludge occurs with the treatment of organic matter in the wastewater. Normally, after dehydration, the surplus sludge is dumped or disposed of as it is, or incinerated. However, in recent years, the lack of waste disposal site, the generation of harmful organic chlorine compounds such as dioxin accompanying combustion is a major problem, such as reducing the discharge of surplus sludge or reducing the volume of surplus sludge generated. The establishment of technology became a priority.

In order to meet these demands, (1) a method using so-called anaerobic digestion in which sludge is solubilized by anaerobic microorganisms, and (2) sludge acid or alkali is added. Perishable sludge such as the method of solubilizing sludge by (3) solubilizing sludge by ozone oxidation, and (4) decomposing and solubilizing sludge using the lytic action of aerobic microorganisms. Drainage treatment methods in combination with the solubilization method have been adopted or proposed.

However, these conventional sludge reduction methods have the following problems. That is, the wastewater treatment method using anaerobic digestion of (1) as the sludge sensitization method is advantageous in that it suppresses energy consumption and yields useful by-products such as methane gas, but the reaction rate of the digestion reaction is slow, The treatment efficiency of surplus sludge tends to be very bad. In this case, it is necessary to considerably lengthen the residence time of the sludge by using a large-sized reaction tank, and in addition to the enlargement of the equipment, there is a possibility that the economical efficiency may deteriorate eventually. Moreover, in the method of using the acid, alkali, etc. of said (2), a large amount of chemical | medical agents and these supply systems are needed, and economical efficiency is not necessarily enough.

On the other hand, in the method of using ozone oxidation of (3), a large amount of drugs, heat sources, and the like are unnecessary. However, a general ozone oxidizing tank is a simple device which simply blows ozone into a water tank, and it is hard to say that the utilization efficiency of ozone is high. In order to improve this, a method of supplying microbubbles of ozone using an acid substrate or the like can be considered, but in this case, clogging of the acid substrate is likely to occur, thus requiring frequent maintenance (maintenance). Tend to be done.

On the other hand, the method of using the aerobic microorganism according to the above (4) does not use a large amount of drugs or ozone gas, but a large treatment tank tends to be needed, and as a result, the wastewater treatment apparatus or the entire facility becomes large. Throw it away. In addition, when the microorganism is treated with a thermophilic cell in a heated state (for example, 50 to 70 ° C.), the solubilization effect of the sludge may be increased, and the heat-denatured effect of the sludge by heating may be expected.

However, there is a concern that the dissolution efficiency of oxygen is further lowered with the increase of temperature, and the useful effects are canceled out. In addition, when aeration of a large amount of gas (air) is prevented in order to prevent such a decrease in the dissolution efficiency, the amount of heat radiation to the outside is increased, which is preferable to waste heat energy for heating and warming. There is a phenomenon that could not be.

This invention is made | formed in view of such a situation, and when processing organic wastewater, etc., while eliminating the conventional undesirable phenomenon, such as the increase of energy consumption, the amount of surplus sludge which generate | occur | produces, or the efficiency of the surplus sludge produced | generated It is an object of the present invention to provide a sludge reduction apparatus, a sludge reduction method, a wastewater treatment apparatus using the same, and a wastewater treatment method that enable the salivation.

1 is a configuration diagram schematically showing a first embodiment of a wastewater treatment apparatus according to the present invention.

2 is a schematic sectional view (partially constitutional diagram) showing the internal structure of the sludge reduction apparatus 3.

3 is a perspective view showing the main portion thereof.

4 is a schematic sectional view showing a part of the porous plate group 33.

5 is a configuration diagram schematically showing a second embodiment of the wastewater treatment apparatus according to the present invention.

6 is a configuration diagram schematically showing a third embodiment of the wastewater treatment apparatus according to the present invention.

7 is a configuration diagram schematically showing a third embodiment of the wastewater treatment apparatus according to the present invention.

8 is a schematic sectional view (partially constitutional diagram) showing another sludge reducing apparatus 300.

9 is a schematic sectional view (partial configuration diagram) showing another sludge reducing device 310.

10 is a schematic sectional view (partially constitutional diagram) showing another sludge reducing device 320.

11 is a schematic sectional view (partially constitutional diagram) showing another sludge reducing device 330.

12 is a configuration diagram schematically showing another embodiment of the wastewater treatment apparatus according to the present invention.

In order to solve the said subject, the sludge perception apparatus which concerns on this invention is supplied with the to-be-processed liquid which contains activated sludge and whose BOD in a liquid powder is less than 50 mg / L, A sludge treatment section for generating turbulent flow in the liquid to be treated and agitating the liquid to be 20% or more in oxygen treatment efficiency, and a sludge treatment portion, which is connected to oxygen (O ₂ ) and ozone (O _3). ) Or a supply unit for supplying hydrogen peroxide (H ₂ O ₂ ).

On the other hand, the method for treating sludge according to the present invention includes oxygen (O ₂ ), ozone (O ₃ ), or hydrogen peroxide (H ₂ O) in a to-be-processed liquid containing activated sludge and having a BOD of less than 50 mg / L. ₂ ) A supply process for supplying the sludge and stirring and generating turbulence in the treated liquid so that the oxygen transfer efficiency to the liquid to be treated is 20% or more, preferably 25% or more, and particularly preferably 30% or more. Process. In the present invention, the "oxygen transfer efficiency" refers to the ratio of dissolved oxygen amount to supplied oxygen amount when 20 ° C air is supplied into fresh water having an oxygen concentration of 0 mg / L.

In the apparatus and method for treating sludge, oxygen gas, ozone gas, or hydrogen peroxide are supplied to a processing liquid containing activated sludge used for biological treatment such as organic wastewater, and these are mixed. Usually, in biological treatment such as organic wastewater, sludge used in drainage treatment in main processes such as activated sludge tanks, biological treatment tanks, reaction tanks, etc., is rich in nutrients and the growth of cells is performed, and BOD in the liquid powder. (Biochemical Oxygen Demand) shows a relatively high value. On the contrary, the present invention is to be treated with a treatment liquid which is less active than sludge for use in biological treatment and can be discharged as surplus, that is, a treatment liquid whose BOD in the liquid fraction is less than 50 mg / L.

Then, turbulence is generated in the liquid to be treated supplied with oxygen and the like, stirred and mixed, and the oxygen transfer efficiency with respect to the liquid to be treated is made 20% or more. As a result, chemical species having an oxidizing ability transferred to the liquid to be treated oxidize the cells and promote solubilization of sludge. At this time, when the oxygen transfer efficiency is less than 20%, it is difficult to realize the solubilization of sludge at a sufficient treatment efficiency even with a liquid having a low eutrophic value, and it is difficult to achieve a desired reduction ratio. There is this.

Moreover, it is preferable if thermophilic aerobic bacteria exist in a to-be-processed liquid. When the treatment liquid to which the thermophilic aerobic bacteria is added is treated in a heated or heated state (for example, 50 to 70 ° C.), the solubilization efficiency of the sludge can be increased by the lytic action, and the organic matter resolution can be obtained even in the heated state. In addition, the reduction effect of the chemical oxygen demand (COD) as well as the reduction can be enhanced. In addition, when the treatment temperature is increased, the dissolution efficiency of oxidizing factors such as oxygen tends to decrease, and conventionally, in order to prevent such a decrease in dissolution efficiency, aeration of a large amount of gas (air) or the like is performed. Etc., this causes waste of thermal energy. On the contrary, in the present invention, the oxygen transfer efficiency is kept high by stirring by turbulence, so that the increase in the amount of aeration is suppressed.

Specifically, it is preferable to block bubbles or liquids in the liquid to be treated or to change the direction of the bubbles or liquids. In this case, at least a part of the flow of the liquid to be treated is disturbed due to the blocking or the direction change of bubbles or liquid flow, that is, the uniformity of the flow of the liquid to be treated is disturbed and turbulence is likely to occur. .

In order to block the bubble or liquid flow in the to-be-processed liquid, what is necessary is just to provide a stirring part in the container which comprises a sludge process part, and to comprise a several porous plate which has a some hole which penetrates in a thickness direction. In particular, at least one first hole of the plurality of holes formed in the at least one porous plate of the plurality of porous plates is formed in another porous plate disposed adjacent to the porous plate and is located at the shortest distance from the first hole. It is more suitable if it is installed coaxially with a 2nd hole. Specifically, a plurality of holes formed in two porous plates disposed adjacent to each other among the plurality of porous plates may be arranged in a staggered arrangement (hound-like shape, browning shape).

Further, the wastewater treatment apparatus according to the present invention is a wastewater treatment apparatus using the sludge perception apparatus according to the present invention, wherein the organic wastewater is supplied and the organic wastewater is biotreated by activated sludge, and the biological treatment unit And a solid-liquid separator separated from the treated water and the activated sludge obtained by the biological treatment unit, and supplying at least a portion of the activated sludge separated from the solid-liquid separator to the sludge treatment unit described above. .

On the other hand, the wastewater treatment method according to the present invention is a wastewater treatment method using the sludge treatment method according to the present invention as described above, which comprises a biotreatment step of biotreating organic wastewater with activated sludge, and The process may further include a solid-liquid separation step of separating the obtained treated water and the activated sludge, and the supplying step may be a step of supplying at least a portion of the activated sludge separated in the solid-liquid separation step.

In this way, it becomes possible to suppress the generation of surplus sludge in the treatment of organic wastewater.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. In addition, unless otherwise indicated, the positional relationship of up, down, left, right, etc. shall be based on the positional relationship shown in drawing. In addition, the dimension ratio of drawing is not limited to the ratio shown.

1 is a configuration diagram schematically showing a first embodiment of a wastewater treatment apparatus according to the present invention. The wastewater treatment apparatus 10 includes a biological treatment tank 1 (biotreatment section) in which raw water W as organic wastewater is supplied through a piping line (hereinafter referred to as a line) L1, and this biological treatment The tank 1 is equipped with the solid-liquid separation tank 2 (solid-liquid separation part) connected through the line L2. This biological treatment tank 1 contains activated sludge, and an aerator 1a such as an air diffuser connected to a blower V is provided therein. From the blower V, the gas containing oxygen gas, such as air, is supplied into the biological treatment tank 1 through the aerator 1a. In addition, the biological treatment tank 1 and the solid-liquid separation tank 2 are also connected by the line L4.

In addition, the sludge-sensing device 3 (sludge treatment unit) according to the present invention is connected to the solid-liquid separation tank 2 via a line L5. The sludge reduction apparatus 3 includes a gas supply source 11 (gas supply unit) for storing or generating a gas containing oxygen gas such as air or a gas Go by ozone by an air line L20. ) Is connected.

FIG. 2: is a schematic cross section which shows the structure of this sludge-sensing apparatus 3. As shown in FIG. In the sludge-sensing device 3, a shaft 35 extending to the center of the shaft is disposed in a substantially cylindrical processing tank 31 (sludge treatment tank) in which both ends are substantially hermetically sealed. The upper end part of the shaft 35 is mechanically connected to the motor M in the drive part 39 arrange | positioned at the top of the process tank 31. As shown in FIG. On the other hand, the lower end of the shaft 35 is released from the inside of the processing tank 31, and is driven up and down by a predetermined period and stroke in the arrow A direction (i.e., vertical direction) shown by the operation of the driving unit 39. Is moved. In this shaft 35, a large number of disk-shaped porous plates 33 _n (subscript n denotes arbitrary positions) is fixedly arranged at predetermined intervals substantially coaxially, whereby the porous plate group 33 (stirring portion) is provided. It consists.

The bottom part of the line L5 is connected to the bottom part of the process tank 31, and the to-be-processed liquid W 'is supplied to the lower part of the process tank 31. FIG. On the other hand, the line L10 is connected to the upper wall of the processing tank 31, and the processed liquid is conveyed to the biological treatment tank 1 from the upper part of the processing tank 31. As shown in FIG. Furthermore, the line L20 connected to the gas supply source 11 is connected to the bottom of the processing tank 31.

Here, the specific structure of the stirring part 33 of the sludge reduction apparatus 3 is demonstrated. 3 is a perspective view showing the main portion (that is, the stirring portion 33) of the sludge reduction apparatus 3, and shows a part of the porous plate group 33 that is the stirring portion. 4 is a schematic cross-sectional view which shows a part of the porous plate group 33. As shown in both figures, the plurality of holes H _n penetrating in the thickness direction are formed in each porous plate 33 _n . Moreover, the perforated plate 33 _n of arbitrary positions is a hole provided in the adjacent perforated plates 33 _n-1 and 33 _{n + 1} , and each perforated plate 33 _n-1 , 33 _n , 33 _{n + 1} . there is a horizontal position are arranged so that they do not match the _{(H n-1, H n} , H n + 1).

In other words, the porous plate group 33 includes a plurality of holes H _n (first holes) formed in an arbitrary porous plate 33 _n and upper and lower porous plates 33 _n-1 and 33 _n adjacent thereto. _A plurality of holes H _{n-1, n + 1} (second holes) formed in ₊₁ ) are arranged in different plane positions. That is, for each adjacent porous plate 33 _n , the center (axis) positions of the holes H are alternately arranged, and arranged in staggered arrangements (hounds, lozenges). Incidentally, a plurality of the porous plate (33 _n) wherein the hole (H _n) formed on one perforated plate (33 _n) of the arbitrary two disposed adjacent to selected trial (33 _n) (the first hole) and the other Among the holes H _{n-1, n + 1} formed in the perforated plate 33 _{n-1, n + 1} , the hole (second hole) located at the shortest distance with the first hole is non-coaxial (the hole is If it is a round hole, it is provided so that it may become non-concentric.

Incidentally, the arrangement intervals (installation intervals) of these holes may be at regular intervals with respect to all the holes, or may be appropriately and arbitrarily adjusted depending on the hole position in the porous plate 33. In addition, the material, hole diameter, hole quantity, hole arrangement, and the like of the porous plate 33 are not particularly limited.

An embodiment of the wastewater treatment method of the present invention using the wastewater treatment apparatus 10 configured as described above will be described below. First, the raw water W of organic wastewater is supplied to the biological treatment tank 1 through the line L1, and the blower V is operated to supply air or the like into the biological treatment tank 1, and the raw water W ) And the treated water (Wk), which is a mixed liquid of activated sludge (S), is subjected to aerobic treatment while stirring and aeration (biotreatment process).

Next, the to-be-processed water Wk is transferred to the solid-liquid separation tank 2 via the line L2, and it separates into the treated water Ws which is liquid, and the activated sludge S as solid content (solid-liquid separation). fair). This treated water Ws is taken out through the line L3 as blue water. On the other hand, the activated sludge S separated from the treated water Ws is taken out from the bottom of the solid-liquid separation tank 2, and a part thereof is returned to the biological treatment tank 1 through the line L4 as a return sludge. do.

Meanwhile, the remainder of the activated sludge S separated in the solid-liquid separation tank 2 is supplied as a concentrated surplus sludge to the lower portion of the treatment tank 31 of the sludge reduction apparatus 3 through the line L5 ( Introduction). Together with the supply of the activated sludge S or after the sludge amount in the processing tank 31 becomes a certain amount of liquid, the gas Go is supplied from the gas supply source 11 to the lower portion of the processing tank 31. In addition, by driving the drive unit 39 to drive the shaft 35 up and down, the plurality of porous plates 33 are reciprocated up and down. The driving period and the driving stroke at this time are not particularly limited, and can be, for example, several rpm to several hundred rpm and several cm to several ten cm, respectively.

By the vertical movement of the porous plate 33 as described above, vortices in a mixed phase containing gas Go are constantly formed between the porous plates 33. Specifically, as shown in FIG. 4, the gas-liquid solid phase mixture including fine bubbles such as air passes upwardly so as to pass through the hole H _n of the porous plate 33 _n . Although flowing, the flow is blocked or shielded by the perforated plate 33 _n-1 located upward, and part of the flow is turned downward. Therefore, in the site, the upstream and the downstream are mixed and disturbed in a complicated manner, and a turbulent state including vortex and the like is constantly generated. Such a state arises in the site | part near each hole H _n of each porous plate 33 _n , and the stirring and mixing of the to-be-processed liquid W 'are fully performed as a whole.

In addition, when passing through the hole H _n provided in the porous plate 33 _n , a high speed flow such as a jet stream having a very high flow rate may occur. Therefore, in the processing tank 31, a substantially complete stirring / mixing state, which can also be referred to as a mixing state due to a torrent, is realized. As a result, bubbles such as air are very fine.

As a result, the movement speed (efficiency) of oxygen or ozone from the bubble to the liquid phase and from the liquid phase to the activated sludge S is dramatically increased. For example, the oxygen transfer capacity coefficient K _{La at} this time reaches up to 400 h ⁻¹ . And oxygen transfer efficiency reaches 20% or more, sometimes 80% or more. On the other hand, in the conventional aeration tank conventionally used, K _La is the grade which does not become 10h <^-1> in general, and oxygen migration efficiency is the grade which does not become 10%. That is, the dissolution efficiency of oxygen or ozone contained in the gas Go into the liquid phase is significantly higher than in the prior art, and a very high BOD load is realized. Therefore, the efficiency of the oxidative decomposition reaction of the microbial cells constituting the activated sludge (S) can be remarkably improved, and the activated sludge (S) can be solubilized with high efficiency (a sludge treatment step).

In addition, according to the findings of the present inventors, the high transfer efficiency of oxygen or ozone in such a sludge-sensing device 3 is expressed in a wide temperature range from a low temperature region to a high temperature region, and thus does not depend on the temperature conditions. Even if the supply amount (aeration amount) of the gas Go to the processing tank 31 is small, the decrease in the solubilization rate of the activated sludge S is suppressed. Therefore, since the supply amount of the gas Go can be reduced, the amount of heat emitted from the outside of the sludge reduction apparatus 3 by the gas Go, that is, the amount of heat dissipation, can be reduced. As a result, when a heat source is provided in the sludge reduction apparatus 3 and the activated sludge S in the processing tank 31 is heated or heated, the consumption of thermal energy can be reduced to achieve vitalization.

In addition, since sufficient agitation and mixing of the activated sludge S and the gas Go are performed in the sludge reduction apparatus 3, the contact frequency of dissolved oxygen or ozone with the microbial cells constituting the activated sludge S ( Probability), contact time, contact amount, etc. are significantly increased. In addition, the microbial cells may be formed by the cavitation effect due to the repetition of the compressive and expansion forces generated by the high-speed flow between the porous plates 33 and the porous plates 33. The effect of mechanically breaking down cells is also achieved. Therefore, by these, oxidative decomposition reaction of microbial cells is further promoted, and solubilization of activated sludge (S) is further enhanced.

In addition, since the periphery of the porous plate 33 is covered by the inner wall of the processing tank 31, the gas-liquid and solid-liquid mixture as described above diffuse or spread in the radial direction (direction toward the outer circumference) of the porous plate 33. Dissipation is forcibly hindered. Therefore, the oil pressure of the mixed phase flows on the contrary, rather than decreases, and the activated sludge S and the gas Go are stirred and mixed more strongly. Therefore, there is an advantage that the solubilization of activated sludge (S) is further enhanced.

In addition, if the microorganisms, such as thermophilic bacteria and thermophilic aerobic bacteria, exist in the to-be-processed liquid W 'in the process tank 31, for example, bacteria belonging to the genus Bacillus, By heating (W '), the solubilization efficiency of the activated sludge can be increased by sufficiently inhibiting its proliferation by the heat denaturing effect of the main cells constituting the activated sludge and by the lytic action of thermophilic aerobic bacteria. Therefore, the ratio of the inorganicized sludge becomes high compared with the past, and COD component can also be fully reduced. In this case, it is preferable to connect the cell adding portion (not shown) for storing such thermophilic aerobic bacteria to the pipe line L5 or the treatment tank 31, or it is added in advance in the biological treatment tank 1 or the like. Also good.

With such sufficient solubilization of the activated sludge S in the sludge reduction apparatus 3, the microbial cells are converted into water, carbon dioxide, other lower carbohydrates, organic acids, and the like, and the liquid component (solution) containing them, Transfer to the biological treatment tank (1) through the line (L10). These organic components, especially BOD components, become nutrients in the sludge treatment in the biological treatment tank 1 and are circulated for biological treatment.

Here, in the sludge treatment step in the sludge reduction apparatus 3, it is suitable to process the activated sludge S so as to satisfy the relationship represented by the following expression (1).

Here, E is the solubilization amount of the activated sludge S in the sludge reduction apparatus 3, S _in is the amount of organic matter in the raw water W supplied to the biological treatment tank 1, and α is the sludge reduction apparatus ( The ratio of activated sludge (S) which is completely oxidized among the activated sludge (S) supplied to 3) is a, and the conversion coefficient of the activated sludge (S) returned to the biological treatment tank (1) to organic matter, b ₁ is the conversion factor to the activated sludge (S) of the organic substances contained in the raw water (W), b ₂ is the elution (溶出) conversion factor to the organic active sludge (S) of in the sludge in the solubilization, and solubilization treatment liquid to the treatment step, β Denotes the self-decomposition coefficient of sludge, and X denotes the amount of sludge in the sludge sensitive apparatus 3, respectively. Here, when the value of β is small, the term of βX may be ignored.

Regarding the discharge out of the system of surplus sludge, it is required to make a small amount as much as possible, and it is ideal that there is no discharge at all. Therefore, assuming such ideal conditions, the relationship expressed by the following equation (2) is satisfied with respect to the mass balance of the cell concentration in the activated sludge S (here, referred to as MLVSS concentration).

Where V is the effective volume of the biological treatment tank 1, dx / dt is the rate of change of the MLVSS concentration, (dx / dt) _s is the rate of growth of the MLVSS, and βX is the amount of sludge in the sludge monitoring apparatus 3. E represents the amount of self-decomposition and the solubilization amount of the activated sludge (unit is, for example, kg / day) in the sludge reduction apparatus 3, respectively.

In addition, in a state in which normal biological treatment is performed in the biological treatment tank 1 and the MLVSS concentration in the biological treatment tank 1 is maintained substantially constant (normal state), the MLVSS concentration in the left side of the expression (2) is shown. The rate of change (dx / dt) becomes substantially zero. In this case, therefore, the relation represented by the equation (3) is established.

That is, when the solubilization amount of the activated sludge S in the sludge reduction apparatus 3 is equal to the generation amount of the activated sludge S in the state of normal biological treatment, the amount of discharge from the system of surplus sludge is discharged. It is also possible to make the limit to as little as possible and to zero. More specifically, reduction of activated sludge S is achieved by solubilization and inorganicization (conversion to water and carbon dioxide gas).

Here, for example, the amount of activated sludge S added to the sludge reduction apparatus 3 is SG (kg / day), and the reduction rate in the single cycle treatment in the sludge reduction apparatus 3 is 35. When it is set to%, the solubilization amount E of the activated sludge S is 0.35 × SG. Of these, when the ratio of activated sludge S that is oxidized and gasified, i.e., α in Equation 1 is 0.2 (20%), the remaining 80% (ie, SG x 0.28) that is not gasified becomes the next processing cycle. It becomes an added organic substance (especially a COD component).

In addition, if a in Formula (1) is 0.6, b ₁ is 0.3, b ₂ is 0.1, and β is sufficiently small, and the third term is ignored, Equation 1 is expressed as E = {S _in × 0.3 + E × (1-0.2) × 0.6 × 0.1}, so if you solve this for E,

Becomes At this time, the increment of the COD component mainly injected into the biological treatment tank 1 is "E * (1-α) * a * b2" which is _{2nd in} the right side of Formula (1), Specifically, E X (1-0.2) x 0.6 x 0.1 (= 0.048 · E).

Therefore, according to the amount of activated sludge S used according to the load of raw water W and its drawing amount (that is, the supply amount of activated sludge S to the sludge sensing apparatus 3), The sludge reduction apparatus 3 is configured to satisfy the relationship represented by 1, or the sludge reduction apparatus 3 is activated so that the relationship of Equation 1 is satisfied according to the capacity and performance of the sludge reduction apparatus 3. By performing the operation of adjusting the supply amount of (S) and the supply amount of gas (Go), the apparent oxidative decomposition rate of the organic substance (MLVSS) contained in the activated sludge (S), which is surplus sludge, can be approximately 100%. Thereby, it becomes possible to make the discharge | emission of surplus sludge out of a system substantially zero. And when it is not necessary to make the discharge | emission of surplus sludge zero in the plan of a facility, what is necessary is to multiply the target reduction ratio by the right side of Formula (1), and solve.

In addition, the coefficient b ₁ shown in expression (1), the value by the aqueous phase (性狀) or the like of organic wastewater to be processed slightly changes, but there is a tendency generally takes a value near 0.3. On the other hand, is a parameter that is determined depending coefficient a and the coefficient b is _2, represents a range of values by the solubilizing method, and the coefficient α is, the sludge supply amount or the like of the configuration condition, gas (Go) of gamyong device 3. Therefore, by obtaining data in advance for these coefficients at the time of trial run etc., the substantially complete solubilization process of the surplus sludge mentioned above can be performed smoothly.

Therefore, according to the wastewater treatment apparatus 10 according to the present invention and the wastewater treatment method of the present invention using the same, it is possible to sufficiently prevent generation of surplus sludge when biologically treating raw water W of organic wastewater, and in particular, By performing a control operation based on the solubilization amount of the activated sludge S in the sludge reducing apparatus 3 as described above, the discharge of the surplus sludge can be made almost zero. In the sludge treatment apparatus 3, when the sludge treatment step is performed, the oxygen transfer efficiency and the oxidative decomposition efficiency of the cells are significantly increased in a wide temperature range, so that even if the supply amount of gas (Go) is reduced, The solubilization amount of sludge S can be increased significantly compared with the past. In addition, the ratio of the inorganicized sludge is higher than in the related art, and the COD component can be reduced. In addition, dissipation of the amount of heat due to gas Go can be sufficiently suppressed, and as a result, increase in energy consumption can be prevented.

In addition, in the solubilization of the activated sludge S, it is possible not only to use a drug but also to improve the economic efficiency. In addition, by increasing the treatment efficiency of the activated sludge S, the efficiency of the entire process can be increased, thereby contributing to the realization of rapid drainage treatment. In addition, when ozone is used as the gas Go, the oxidizing ability of the cells is increased as compared with the case of using a gas containing oxygen such as air, but even in this case, the ozone dissolution efficiency is significantly improved as compared with the prior art. Sufficient solubilization of activated sludge (S) is possible even if the amount of used is reduced. Therefore, the consumption amount of ozone can be reduced, and further, the scale of the gas supply source 11 can be reduced, thereby making it possible to further improve the economics.

In this case, preferably, the MLVSS concentration in the activated sludge S introduced into the sludge reduction apparatus 3 is measured online or offline, and the activated sludge S to the sludge reduction apparatus 3 is measured based on the measured value. It is useful to carry out a control operation to adjust the supply amount and / or the supply amount of the gas Go. In order to determine the concentration of organic matter in activated sludge (S), the ratio of MLVSS in MLSS (Mixed Liquor Suspended Solid) contained in activated sludge (S) is measured in advance, and the actual value of MLSS concentration is multiplied by the ratio. Also suitable. Such control operation may be manual or automatic, or may be performed continuously or intermittently.

5 is a configuration diagram schematically showing a second embodiment of the wastewater treatment apparatus according to the present invention. In this wastewater treatment apparatus 100, the slurry pump 61 and the MLSS system 62 are provided in order from the upstream side on the line L5, and the control valve 63 is provided on the line L20. In addition, they have the same structure as the wastewater treatment apparatus 10 shown in FIG. 1 except that these are connected to the control part 64. As shown in FIG.

In the wastewater treatment apparatus 100, the MLSS concentration in the activated sludge S sent out from the solid-liquid separation tank 2 to the sludge reduction apparatus 3 is measured online by the MLSS system 62, and the value is controlled. Is output as (64). The control unit 64 has functional units such as a memory and a CPU, and calculates the MLVSS concentration from the actual value of the MLSS concentration. Subsequently, the amount of transfer of the activated sludge S by the line L5 is adjusted by outputting the pump ON / OFF signal to the slurry pump 61 based on the concentration value. At the same time, the opening degree adjustment signal of the valve is output from the control part 64 to the control valve 63, and the amount of gas Go according to the supply amount of the activated sludge S is transferred to the control device 63 by the line L20. (송) to send. By such a control operation, the treatment operation of the activated sludge S according to the load fluctuation and the like can be performed satisfactorily and efficiently.

6 is a configuration diagram schematically showing a third embodiment of the wastewater treatment apparatus according to the present invention. This wastewater treatment apparatus 101 uses the sludge reduction system 4 which multiplexed the sludge reduction apparatus instead of the sludge reduction apparatus 3 in the wastewater treatment apparatus 10 shown in FIG.

The sludge reduction system 4 divides the sludge treatment tank 41 into a state where the liquid component is circulated by the partition wall 304, and the sludge reduction apparatus 3 shown in FIG. By arranging the sludge sense unit 3a having a substantially equivalent configuration, a plurality of sludge sense units 3a are connected and installed. Each sludge-sensing unit 3a is formed in the cylindrical cylindrical member 31a (corresponding to the processing tank 31 of the sludge-sensing device 3 shown in FIG. 2) along the shaft center. The combined shaft 35 is connected, and the several perforated plate 33 is penetrated and coaxially fixed at fixed intervals to this shaft 35. A line L20 leading from the gas supply source 11 is branched and connected to each section.

In the wastewater treatment apparatus 101 configured as described above, the activated sludge S as surplus sludge is discharged from the solid-liquid separation tank 2 by the line L5, and the gas Go is supplied from the gas supply source 11 by the line L20. By this, it is supplied to each compartment of the sludge perception system 4. In each compartment, the activated sludge S is sufficiently mixed with the gas Go by the powerful stirring action of the sludge perturbing unit 3a, and is solubilized and moved from the front section to the rear section. The solubilized activated sludge S is conveyed to the biological treatment tank 1 via the line L10.

According to such a wastewater treatment apparatus 101, since it has the sludge-sensing system 4 comprised by installing two or more sludge-sensing units 3a, it is especially effective for large-capacity surplus sludge processing. In addition, similarly to the sludge reduction apparatus 3 shown in Figs. 1 and 2, since very high gas transfer efficiency is achieved in each section, solubilization of the activated sludge S can be performed sufficiently and quickly. In particular, when the sludge reduction system 4 as a whole is operated so as to satisfy the relationship represented by the above expression (1), it is easy to reliably perform approximately complete solubilization, and it is sufficient to cause deterioration of the water quality of the treated water Ws. It can be suppressed.

In addition, in the sludge reduction system 4, since the periphery of the perforated plate 33 is enclosed by the cylinder 31a, the strong mixed phase which occurred in the shanghai east of the perforated plate 33 to the outside of the cylinder 31a. Since it is prevented to dissipate, there is an advantage that the high moving efficiency of the gas Go can be properly maintained. In addition, since the porous plate 33 is provided in each section using the sludge treatment tank 41, it is possible to cope with the large-capacity processing with a simplified facility configuration rather than equipping the plurality of sludge reduction apparatuses 3. In addition, since the activated sludge S as surplus sludge is supplied to each compartment of the sludge-sensing system 4, the processing load in the compartment at the foremost stage can be reduced as compared with the case of supplying only the compartment at the foremost stage. By such parallel processing, the processing efficiency of the entire system can be improved.

7 is a configuration diagram schematically showing a fourth embodiment of the wastewater treatment apparatus according to the present invention. The wastewater treatment apparatus 102 is provided with the solid-liquid separation tank 6 and the finishing treatment tank 7 on the discharge line from the sludge reduction apparatus 3, and the wastewater treatment apparatus 10 shown in FIG. Different. And the sludge reduction apparatus 3 and the solid-liquid separation tank 6 are connected by the line L6, and the liquid component is sent to the finishing treatment tank 7 by the line L7 from the solid-liquid separation tank 6, The solid is taken out from the line L9, and a part is conveyed to the biotreatment tank 1 by the line L91, and the other part is conveyed to the sludge monitoring apparatus 3 by the line L92, respectively. Discharged by line L93. The treated water treated in the finishing tank 7 joins the line L3 by the line L8.

When the solid-liquid separation tank 6 contains the hardly decomposable inorganic solids in the raw water W, or the processing conditions such that all of the activated sludge S is not solubilized in the sludge reduction apparatus 3, It is for separating solid content and residual sludge from liquid content, and functions as a second settling tank in the wastewater treatment apparatus 102. As the finishing treatment tank 7, it is preferable to use an anaerobic treatment tank using methane bacteria such as UASB (Upflow Anaerobic Sludge Blanket).

According to the wastewater treatment apparatus 102 having such a configuration, similar to the wastewater treatment apparatuses 10, 100, 101 of the other embodiment, sufficient solubilization of the activated sludge S is achieved and the sludge sensing apparatus 3 is provided. When solid content or residual sludge is contained in the solution which passed through, these can be effectively removed. In addition, since the liquid component from which solid content has been removed is further sent to the line L3 after further biological treatment or the like in the finishing treatment tank 7, the properties and water quality of the treated water Ws can be maintained well.

The sludge-sensing device of the wastewater treatment apparatus according to the present invention is not limited to the above-described configuration. Hereinafter, another configuration of the sludge reduction apparatus will be described.

FIG. 8: is a schematic cross section (partial block diagram) which shows the sludge reduction apparatus 300 of the other form which can be used by the wastewater disposal apparatus shown in FIG. In the sludge reduction apparatus 300, unlike the sludge reduction apparatus 3 shown in FIG. 2, instead of the drive part 39, the flow adjusting means for agitating by adjusting the flow inside the sludge reduction apparatus 3 ( 301 is provided. Specifically, in this sludge reduction apparatus 300, the porous plate group 33 is fixed to the fixed shaft 34 which runs along the central axis of the processing tank 31. As shown in FIG. The structure of the porous plate group 33 itself is the same as that of the sludge sensing apparatus 3 shown in FIG. 2. The line L10 leading to the biological treatment tank 1 is connected to the upper part of the treatment tank 31, and the line L5 connected to the solid-liquid separation tank 2 is connected to the lower part. Same as).

Each end part of the circulation line L50 is connected to the upper part and the bottom part of the process tank 31, and the branch line which has the pumps P1 and P2 provided in parallel in the middle of this circulation line L50, respectively. L51 and L52 are provided. The discharge directions of the pumps P1 and P2 are opposite to each other, as indicated by arrows t1 and t2 shown, respectively. Thus, the liquid circulation part 301 is comprised from circulation line L50, branch line L51, L52, and pump P1, P2.

In addition, the line L0 which continues from the gas supply source 2 branches in the middle, one line L21 is connected to the bottom of the process tank 31, and the other line L22 is connected to the line L50. . In the lines L21 and L22, flow rate adjusting valves V21 and V22 are provided, respectively, and together with the liquid circulation part 302, the flow adjusting means 301 is formed.

At the time of operation of this sludge reducing apparatus 300, the processing liquid W 'containing surplus sludge is supplied from the solid-liquid separation tank 2 by the line L5, and at the same time, the gas from the gas supply source 11 Aeration and the like are supplied to the lower portion of the treatment tank 31 through L21 (air supply process). At the same time, the pump P1 is operated and aeration and the like are supplied to the lower end side of the line L50 via the line L22 (air supply step).

Then, the supply flow rate of the processing liquid W 'to the sludge reducing apparatus 300 is adjusted so that the liquid level in the processing tank 31 is slightly higher than, for example, the connection end of the upper portion of the processing tank 31 in the line L50. The liquid to be treated W 'is forcedly circulated in the processing tank 31 by introducing air into the lower portion and forced circulation of the gas liquid by the line L51 while maintaining the same liquid amount. At this time, the to-be-processed liquid W 'distributes the porous plate group 33 downward. After the pump P1 is operated for a predetermined time, the pump P1 is stopped and the pump P2 is started. In this way, the circulation flow in the processing tank 31 is reversed, and the to-be-processed liquid W 'is passed upward.

In the meantime, oxygen contained in air or the like migrates into the liquid W 'to be treated, and the oxidation and decomposition of the cells constituting the activated sludge contained in the liquid is performed by the oxidation ability. In addition, in this case, in order to maintain the processing liquid W 'at a predetermined temperature, a heater or the like may be provided inside or outside the processing tank 31 to heat or keep warm. In this case, the processing liquid W 'may be supplied into the processing tank 31 in a state of being heated or warmed to a predetermined temperature in advance.

Here, for example, when the pump P2 is being operated, the gas-liquid solid phase flow including the microbubbles such as air flows upwardly through the hole H _n of the porous plate 33 _n . , The flow is blocked or shielded by the perforated plate 33 _n-1 located upward, and part of the flow is turned downward. Therefore, in the site, the upstream and the downstream are mixed and disturbed in a complicated manner, and a turbulent state including vortices and the like is constantly generated (see FIG. 4). Such a state arises in the site | part near each hole H _n of each porous plate 33 _n , and the stirring and mixing of the to-be-processed liquid W 'are fully performed as a whole. On the contrary, even in the state where the pump P1 is being operated, turbulence is generated between the porous plates 33 _n by the porous plate group 33, and sufficient stirring and mixing is performed.

In addition, when passing through the hole H _n provided in the porous plate 33 _n , a high speed flow such as a jet flow having a large flow rate may occur. Therefore, in the processing tank 31, a substantially complete stirring / mixing state, which may also be referred to as a mixing state due to a flow, is realized. That is, even if the driver 39 is not used, the same effect as the sludge reduction apparatus 300 can be achieved by the flow adjusting means 301.

That is, the efficiency of dissolution into liquid phases such as oxygen contained in air and the like is significantly increased, and the efficiency of oxidative decomposition reaction of the microbial cells constituting activated sludge is greatly improved, solubilization of activated sludge is promoted (sludge treatment step), Solubilization of the sludge can be sufficiently achieved. The treated water obtained is conveyed to the biological treatment tank 1 via the line L10. The microbial cells are converted to water, carbon dioxide, other lower carbohydrates, organic acids, and the like, and in particular, BOD components in the liquid fraction (solution) containing them can be nutrients in wastewater treatment by activated sludge.

Here, the oxygen transfer efficiency to the processing liquid W 'in the processing tank 31 is the operation output of the pumps P1 and P2, and further, the processing liquid W' circulating in the processing tank 31. It is possible to control by appropriately adjusting the flow rate or flow rate of), the aeration amount of air from the gas supply source 11, the shape, arrangement, and the like of the porous plate 33 _n .

Further, the pump (P1, P2) by switching the operation, since the sequential reversing the direction of the target liquid (W ') and the horn or the like air upstream in the processing tank 31 of, and between the perforated plate (33 _n) It is possible to solve the inevitable retention. Therefore, stirring and mixing with the to-be-processed liquid W 'and air can be further promoted. Therefore, sufficient oxygen transfer efficiency can be easily realized by 20% or more, preferably 25% or more, particularly preferably 30% or more by supply amount or liquid circulation amount of less air or the like.

In the sludge reduction apparatus 300, the agitation is performed by alternately switching in the liquid flow direction without driving the porous plate group 33, so that the movable portion can be reduced, and the reliability and water retention of the apparatus can be improved. The power consumption (for example, power) can be reduced.

In addition, when the holes H _n formed in each of the porous plates 33 _{n in the} porous plate group 33 are arranged in a staggered arrangement, the effect of generating turbulence can be enhanced. Compared to the case of coaxially located at the same position, it is possible to achieve higher oxygen transfer efficiency with the same air supply amount or liquid circulation amount.

9 is a schematic sectional view (partial configuration diagram) showing another sludge reducing device 310. This sludge reduction apparatus 310 is provided with the liquid circulation part 311 instead of the liquid circulation part 302 of the sludge reduction apparatus 300 shown in FIG.

The liquid circulation section 311 has a line L53 branched from the circulation line L50 and parallel to each other, a line L54 connecting the circulation line L50 and this line L53, and a line L54. Three-way valves V33 and V34 are provided at the connecting portions of the over circulation line L50 and the line L53. And on the line L54, the pump P3 which discharges in the direction of the arrow t3 is arrange | positioned.

In the sludge reduction apparatus 310, by switching the flow direction of the gas liquid in the line L50 by opening and closing the valves of the three-way valves V33 and V34 while the pump P3 is operated. The flow direction of the liquid to be processed in the processing tank 31 can be switched.

Specifically, in order to generate an upward flow in the processing tank 31, what is necessary is just to distribute | circulate gas liquid in the direction of the arrow X shown in the line L50. In addition, in order to generate | occur | produce a downflow in the process tank 31, what is necessary is just to distribute | circulate gas liquid in the direction of the arrow Y shown in the line L50. Thereby, only one pump P3 can forcibly flow gas liquid in both the reverse directions in the line L50, and the same effect as the sludge reduction apparatus 300 shown in FIG. 8 can be obtained.

FIG. 10: is a schematic cross section (partial block diagram) which shows the other sludge-sensing apparatus 320. FIG. In the sludge-sensing device 320, the shaft 321 on which the porous plate group 33 is fixed is fixed to the external support 322, while the processing tank 31 is connected to the drive unit 323. have. Here, the penetration part of the shaft 321 in the front part and the bottom part of the process tank 31 is sealed so that sliding is possible. In the sludge reduction apparatus 320, although the porous plate group 33 itself is fixed, the driving section 323 has a constant period in the direction of arrow B (ie, vertical direction) showing the entire processing tank 31. And stroke by stroke. Thereby, the effect similar to moving the porous plate group 33 in the process tank 31 is acquired relatively.

That is, by this drive, relative flow between the porous plate group 33 and the processing liquid W 'in the processing tank 31 occurs, and the flow direction thereof is the processing tank 31 by the drive unit 323. It is frequently switched to the drive cycle of). As a result, turbulent flow of mixed phase such as the liquid to be treated W 'and the air as described above is generated, and strong stirring and mixing are performed. As a result, the same effects as in the other sludge reduction apparatus described above are obtained.

11 is a schematic sectional view (partially constitutional diagram) showing still another sludge-sensing device 330. This sludge reduction device 330 uses two anisotropic valves V33a, V33b and V34a and V34b, respectively, instead of the three-way valves V33 and V34 of the sludge reduction device 310 shown in FIG. By switching between these anisotropic valves V33a, V33b, V34a, and V34b, the same action as the three-way valves V33 and V34 in the sludge reduction apparatus 310 can be performed. Therefore, the function and effect are the same as those of the sludge-sensing device 310. Thus, using two pairs of anisotropic valves instead of two three-way valves is advantageous from an economical point of view, for example, when using a pipe of schedule 100A.

In addition, the wastewater treatment apparatus and treatment method of the present invention are not limited to the biological treatment tank 1 as an essential configuration, and are applicable to the treatment of wastewater containing activated sludge. 12 is a configuration diagram schematically showing an apparatus for treating wastewater containing such activated sludge.

The wastewater treatment apparatus 103 shown in FIG. 12 is lined with the sludge monitoring apparatus (sludge treatment part) 3 connected to the feed line L5 of the to-be-processed liquid W 'containing an activated sludge, respectively. Through L20 and L6, a gas supply source 11 (supply) for storing or generating a gas containing oxygen gas such as air or a gas containing ozone, and a solid-liquid separation tank 6 using gravity settling separation and the like. Is connected. In addition, at the bottom of the solid-liquid separation tank 6, a conveying line L9 connected to the sludge reduction apparatus 3 is connected, and a discharge pipe line L7 for treated water Ws is provided at the upper portion thereof. have.

Herein, the liquid to be treated (W ') has a BOD of less than 50 mg / L in the liquid powder, and part of the activated sludge used for biological treatment such as organic drainage is discharged as a surplus (ie, surplus sludge). Etc. can be mentioned. Such a BOD value is lower than the normal value of the active sludge at the time of being used for biological treatment, and corresponds to the low nutrient value which is difficult to say that it is enough for a sludge to grow.

The to-be-processed liquid W 'having such a property is supplied to the sludge-sensing device 3 through the conduit L5, and aeration and the like are aerated by the gas supply source 11. In the sludge reduction apparatus 3, as described above, stirring and mixing of the target liquid W 'supplied with air or the like are performed, and the cells are oxidatively decomposed to solubilize the sludge in the liquid. This to-be-processed liquid W 'is sent to the solid-liquid separation tank 6, and the separated processed water Ws passes through the pipe line L7, and is sent to the processing equipment etc. which perform water purification treatment. In addition, sludge remaining as a solid without being solubilized is conveyed to the sludge-sensing device 3 through the conduit L9 and circulated.

The sludge-sensing device in the present invention is not limited to the above-described forms, and various modifications can be made without departing from the gist of the present invention. For example, in the processing tank 31, instead of the porous plate group 33, another member capable of partially blocking or shielding the flow direction of the liquid W 'to be treated, for example, a driveable or fixed pin member, A propeller member, another plate shape, a comb shape, a mesh shape, etc., or a combination thereof may be provided. In addition, the shape of the hole H _n formed in each porous plate 33 _n is not limited to what was shown. Further, the porous plate group 33 and the processing tank 31 may be relatively moved, and the processing liquid may be circulated by a pump, and the circulation direction may be changed periodically.

In addition, when ozone-containing gas is used as the gas Go supplied to the sludge reduction system 4 or the like, in order to prevent unreacted ozone from leaking out of the sludge treatment tank 41, The upper part may be closed or sealed with a cover or the like. According to the present invention, however, even when the amount of ozone is reduced, solubilization of the activated sludge (S) can be sufficiently achieved, and in addition, a control operation such as optimizing the amount of use of the activated sludge can be achieved, thereby reducing unreacted ozone itself. There is an advantage to that. In addition, hydrogen peroxide may be used instead of gas (Go), and oxidative decomposition of cells and thus solubilization of activated sludge (S) is promoted by the oxidizing ability.

In the wastewater treatment apparatus 10, the liquid fraction obtained from the sludge reduction apparatus 3 may be introduced into the line L3 and discharged out of the system together with the treated water Ws. In addition, the liquid fraction obtained from the sludge perception system 4 in the wastewater treatment apparatus 101 or the finishing tank 7 in the wastewater treatment apparatus 102 may be conveyed to the biological treatment tank 1. In addition, the number of divisions of the sludge reduction system 4 is not limited to what was shown, and it does not need to divide. In addition, in the wastewater treatment apparatus 101, the activated sludge S solubilized from each section of the sludge treatment tank 41 of the sludge treatment system 4 may be sent to the biological treatment tank 1. Alternatively, the line L6 may be connected to only the frontmost section of the sludge treatment tank 41, and in this case, the activated sludge S solubilized from each section may also be sent out to the biological treatment tank 1. good.

In addition, in the wastewater treatment apparatuses 10 and 101, the solid-liquid separation tank 6 may be provided. In addition, various flocculants may be added to the raw water W of the biological treatment tank 1. Thereby, removal of the hardly decomposable solid content etc. which are contained in raw water W becomes simple, In this case, it is more useful to have solid-liquid separation tank 6 in this case. In addition, in the wastewater treatment apparatus 100, a mass flow controller (MFC), another flow control valve, or the like may be used instead of the control valve 63. In addition, when a thermophilic bacterium such as a bacterium belonging to the genus Bacillus or a bacterium such as thermophilic heat-resistant bacterium is present in the activated sludge S to be treated, the effect of COD removal is also obtained.

<< Example >>

Hereinafter, although the specific Example which concerns on this invention is described, this invention is not limited to this.

<Example 1>

The apparatus which has a structure equivalent to the wastewater treatment apparatus 10 shown in FIG. 1 was prepared. The sludge-sensing device 3 of this wastewater treatment apparatus is formed in a cylindrical container (treatment tank) 31 having an effective volume of 20 liters (liter or less), and has a perforated plate 33 _n (13 cm in diameter and hole diameter). 8 mm phi) is provided with 16 porous plate groups 33 provided at 6 cm intervals. In the treatment tank 31, the treated liquid W 'containing activated sludge at a concentration of 10000 mg / L and having a BOD of 10 mg / L in the liquid powder was supplied at a flow rate of 30 L / h. At the same time, while moving the porous plate group 33 at different driving cycles at 60, 80, 100, and 120 rpm, the air in the processing tank 31 is changed to 5, 7.5, 10 L / min (that is, 15, 22.5, 30 VVH). It was supplied at a flow rate and treated for sludge reduction. Moreover, as a result of supplying air to the fresh water under the same conditions, the oxygen transfer efficiency was all 20% or more.

Here, the unit "VVH" represents a physical quantity of {gas supply volume (Vol.)} / {Effective volume (Vol.)} / H of the treatment tank 31, and the fields such as water treatment technology and fermentation technology. Is a unit generally used in the present invention, and corresponds to a value in which the air supply amount to the sludge-sensing device 3 is standardized to the effective volume of the container (treatment tank). And when processing, the temperature of the to-be-processed liquid in the process tank 31 was kept at 60 degreeC.

As a result, under any condition, the desired reduction ratio (30 to 50%) of activated sludge, that is, the amount of new sludge production (growth of cells) according to the wastewater treatment apparatus 10, for example, is reduced by solubilization A reduction rate such as approximately the amount of decomposition) was achieved. That is, the generation of surplus sludge was not confirmed. In addition, the amount of oxygen dissolved in the liquid to be treated W was measured using an oxygen absorption method using sodium sulfite, and the dissolution rate of oxygen was calculated based on the flow rate of air. Table 1 shows the results of the oxygen dissolution rate under each treatment condition.

Oxygen Dissolution Rate Oxygen Dissolution Rate in Example 1 (kg-O ₂ / m 3 / h) Perforated plate driving cycle (rpm) Air supply flow rate (VVH) 15 22.5 30 60 2.0 2.8 4.5 80 4.2 4.6 7.3 100 4.3 6.1 8.2 120 6.0 8.2 10.7

Thus, according to the present invention, it was confirmed that a very high oxygen dissolution rate was obtained even in a heating condition of about 60 ° C with respect to a solution containing activated sludge.

<Example 2>

Instead of air, ozone-containing gas (ozone concentration: 40 g / Nm 3) is used, and this is supplied into the processing tank 31 at a flow rate of 10, 12.5, 15 VVH, and the driving period of the porous plate group 33 is 80, 100, 120. The wastewater treatment was carried out in the same manner as in Example 1 except that the rpm and the treatment temperature of the liquid to be treated W 'were 20 to 24 ° C. As a result, under all conditions, the desired reduction ratio (30-50%) with respect to activated sludge was obtained by the efficiency more than or equal to Example 1, and generation | occurrence | production of surplus sludge was not confirmed.

The amount of ozone dissolved in the liquid to be treated was measured, and the dissolution rate of ozone was calculated based on the supply flow rate of the ozone-containing gas. Table 2 shows the results of the ozone dissolution rate under each treatment condition. From this, it was found that a very high ozone dissolution rate was obtained.

Ozone Dissolution Rate Ozone dissolution rate in Example 2 (gO ₃ / m ₃ / h) Perforated plate driving cycle (rpm) Ozone-containing gas supply flow rate (VVH) 10 12.5 15 80 282 313 499 100 292 414 556 120 400 500 600

Thus, according to this invention, it was confirmed that very high ozone dissolution rate is obtained with respect to the solution containing activated sludge.

<Example 3>

The effective volume of the processing tank 31 is 1.5L, the porous plate of the shape according to this is used, the temperature of the processing liquid W 'in the processing tank 31 is maintained at 70 ° C, and the processing tank ( The air supply amount to 31) was 0.3 L / min (i.e., 12 VVH) and the drive cycle of the porous plate group 33 was set to 25, 45, 50, 100 rpm in the same manner as in Example 1 Drainage treatment was performed. Table 3 shows the oxygen transfer capacity coefficient (K _La ) and the deactivation rate of activated sludge under each condition.

Oxygen migration capacity coefficient (K _La ) and activated sludge ratio in Example 3 Perforated plate driving cycle (rpm) Oxygen migration capacity factor (K _La ) (h ^-1 ) Reduction rate (%) 25 20 20 50 100 48 100 400 47

As described above, under the conditions of the present embodiment, an oxygen transfer capacity factor K _{La of} 20 (h ⁻¹ ) or more is obtained, and when at least K _La is 100 (h ⁻¹ ) or more, a high reduction ratio of about 50% It was confirmed that it could be achieved.

Comparative Example 1

Sludge reduction treatment was performed in the same manner as in Example 3 except that the liquid to be treated W 'was stirred using a magnetic stirrer instead of the porous plate group 33. The oxygen transfer efficiency and the deactivation rate of the activated sludge at this time are shown in Table 4.

Comparison of oxygen transfer efficiency and reduction rate in Example 3 and Comparative Example 1 Perforated plate driving cycle (rpm) Oxygen migration efficiency (%) Reduction rate (%) Comparative Example 1 Stirring by stirrer 5 20 Example 3 45 22 31 50 32 48 100 82 47

Thus, it was confirmed that Example 3 can achieve a high oxygen transfer efficiency and a reduction rate compared with the comparative example 1.

<Example 4>

The sludge reduction treatment was carried out in the same manner as in Example 3 except that the driving cycle of the porous plate group 33 was 100 rpm, and the temperature of the liquid to be processed in the processing tank 31 was maintained at 25, 60, and 70 ° C. Was performed. In addition, although the Example at the temperature of 70 degreeC is the same conditions as the Example of the temperature of 70 degreeC in Example 3, it is shown again here for convenience of description. Table 5 shows the reduction ratio of sludge contained in the liquid to be treated W under each condition.

Reduction rate of sludge contained in the liquid to be treated (W ') Perforated plate driving cycle (rpm) Treatment liquid temperature (℃) Reduction rate (%) 100 25 10 60 35 70 47

As described above, in the conventional method, the oxygen dissolution efficiency decreases with an increase in the treatment temperature, and as a result, a decrease in the treatment efficiency (that is, the reduction rate) is concerned, whereas in the present invention, the same air supply amount It was confirmed that the increase in treatment rate increased with increasing treatment temperature. As a result, it was confirmed that the thermal energy can be effectively utilized for the reduction treatment, and the increase in the amount of heat radiation to the outside can be suppressed.

As described above, according to the present invention, the dissolution rate of oxygen or the like can be increased, and the oxidative decomposition reaction of the cells is promoted. As a result, solubilization of activated sludge is promoted and generation of surplus sludge can be prevented.

Claims (13)

The treated liquid containing activated sludge and having a BOD of less than 50 mg / L is supplied, and the turbulent flow in the treated liquid is such that the oxygen transfer efficiency of the treated liquid is 20% or more. A sludge treatment section that generates a flow and stirs the liquid to be treated; And a supply unit connected to the sludge treatment unit and supplying oxygen (O ₂ ), ozone (O ₃ ), or hydrogen peroxide (H ₂ O ₂ ). The method of claim 1, The sludge treatment unit has a stirring unit for blocking bubbles or liquids in the liquid to be treated or changing the direction of the bubbles or liquids to stir the liquid to be treated. The method of claim 2, And the stirring unit has a plurality of porous plates provided in a container constituting the sludge treatment unit and having a plurality of holes penetrating in the thickness direction. The method of claim 3, In the plurality of porous plates, at least one first hole among the plurality of holes formed in at least one porous plate of the plurality of porous plates is formed in another porous plate adjacent to the porous plate, and is also the first. A sludge sensing device, characterized in that it is installed coaxially with a second hole located at a shortest distance from the hole. The method of claim 4, wherein The plurality of porous plates is a sludge sense device, characterized in that the plurality of holes formed in two porous plates disposed adjacent to each other of the plurality of porous plates are arranged in a staggered arrangement. . The method according to any one of claims 3 to 5, The stirring unit includes a plurality of porous plates and a driving unit for driving at least one of the containers. The method according to any one of claims 3 to 5, The stirring section is connected to the vessel, and has a liquid circulation section for circulating and circulating the to-be-processed liquid in the vessel, and for switching the flow direction of the to-be-processed liquid to a plurality of different directions. Device. The sludge perception device according to any one of claims 1 to 7, A biological treatment section in which organic drainage is supplied and the organic drainage is biotreated by activated sludge, A solid-liquid separation unit connected to the biological treatment unit and separating the treated water obtained in the biological treatment unit and the activated sludge; And at least a portion of the activated sludge separated by the solid-liquid separator to the sludge treatment unit. A supplying step of supplying oxygen (O ₂ ), ozone (O ₃ ), or hydrogen peroxide (H ₂ O ₂ ) to the to-be-processed liquid containing activated sludge and having a BOD of less than 50 mg / L, And a sludge treatment step of generating and stirring turbulence in the liquid to be treated so that the oxygen transfer efficiency with respect to the liquid to be treated is 20% or more. The method of claim 9, In the sludge treatment step, the bubble or liquid flow in the liquid to be treated is blocked, or the direction of the bubble or liquid flow is changed. As a wastewater treatment method using the sludge reduction method according to any one of claims 8 to 10, A biotreatment process for biotreating organic wastewater by activated sludge, And further comprising a solid-liquid separation step for separating the treated water obtained in the biological treatment of the organic wastewater and the activated sludge, Wherein said supplying step is a step of supplying at least a portion of the activated sludge separated in said solid-liquid separation process. The method of claim 11, In the sludge treatment step, at least the solubilization amount of the activated sludge in the sludge treatment step, the amount of organic matter in the organic wastewater supplied to the biological treatment step, and the organic matter contained in the organic wastewater The amount of activated sludge supplied to the sludge treatment step so that the amount of activated sludge supplied to the sludge treatment step and the amount of activated sludge solubilized in the sludge treatment step are substantially equal to each other, And / or, adjusting the supply amount of oxygen (O ₂ ), ozone (O ₃ ), or hydrogen peroxide (H ₂ O ₂ ). The method of claim 11, In the sludge treatment step, the following formula (1); E: solubilization amount of activated sludge in the sludge treatment step, S _in : amount of organic matter in the organic wastewater supplied to the biological treatment process, α: the ratio of activated sludge completely oxidized among the activated sludge supplied to the sludge treatment process, a: when the part of said activated sludge is returned to the said biological treatment process, the conversion coefficient of this returned sludge to the organic substance, b ₁ : conversion rate of organic matter into activated sludge contained in the organic wastewater, b ₂ : conversion rate of the organic sludge solubilized in the sludge treatment step and eluted in the solubilization treatment liquid, β: coefficient of autolysis of sludge, X: amount of sludge in the sludge treatment step, Solubilizing the activated sludge so as to satisfy the relationship represented by.