JP4840563B2 - Sewage treatment equipment - Google Patents

Description

  The present invention relates to a sewage treatment apparatus for modifying or purifying sludge generated in a water treatment process or sewage containing harmful organic substances and bacteria in water using ozone or an oxidizing agent.

Regarding the sludge reforming, the activated sludge method is widely used in various fields such as sewage treatment because of its high treatment performance. Since this purification principle is based on the action of microorganisms decomposing and removing organic matter in the sewage as a feed, the microorganisms grew and surplus sludge was generated as a result of the treatment. The final disposal amount of this sludge has a high ratio with respect to the final disposal amount of all industrial waste. In Japan, the residual capacity of the final disposal site is extremely small, which is a great cost burden. Under such circumstances, it is desired to reduce surplus sludge as much as possible, and introduction of a sludge reduction method using various means is being studied.
Regarding sludge reduction methods in conventional sewage treatment systems, a part of excess sludge is improved with biodegradability by reforming sludge with a sludge reformer using ozone, and it is returned to the biological reaction tank again. Thus, the organic matter in the sludge is biologically oxidized to reduce the amount of excess sludge (see, for example, Patent Document 1).
The sludge reforming apparatus at this time is as shown in FIG. In FIG. 8, 1 is a sludge to be treated, 2 is an ozone reaction tank, 3 is an ozone generator, 4 is an ozonized gas, 5 is an ozone dissolving means (aeration pipe), 6 is an exhaust ozone gas, 7 is an exhaust ozone decomposition device, 8 is a modified sludge. In addition, 20 is a biological reaction tank and 21 is a sedimentation basin.
A part of the sludge 1 to be treated extracted from the sedimentation basin 21 is supplied to the ozone reaction tank 2. The ozonized gas 4 generated by the ozone generator 3 is supplied into the tower by ozone dissolving means (aeration pipe) 5 installed at the bottom of the ozone reaction tank 2 and is mixed with the treated sludge 1 in a gas-liquid mixture. The harmful exhaust ozone gas 6 undissolved in water is gas-liquid separated in the upper part of the tower, detoxified in the exhaust ozone decomposing apparatus 7, and released into the atmosphere. The reformed sludge 8 that has been treated with ozone is then returned to the biological reaction tank. At this time, most of the MLSS components in activated sludge are biologically derived organic matter, so the cell walls and cell membranes that make up the organism are destroyed by ozone, which has strong oxidizing power, and organic acids and sugars are released from the cells. Is done. By such an action, the sludge becomes readily biodegradable, and when it returns to the biological reaction tank, it is decomposed into inorganic substances and the sludge disappears.
Similar equipment is also considered as a means to promote the production of methane gas in facilities intended to produce methane gas through anaerobic digestion process of surplus sludge and effectively use it as biomass resources. ing.
In addition, regarding the treatment of organic substances in water, the reduction of organic substances such as COD and BOD in water, removal of harmful organic substances such as dioxin, or inactivation of pathogenic viruses such as Escherichia coli and Cryptosporidium, and microorganisms such as protozoa In the water treatment field, a method using the same configuration and operation using ozone for the treatment to be removed and a method for purifying by injecting an oxidizing agent such as hydrogen peroxide instead of ozone are performed. An example of sewage treatment using ozone gas is shown in FIG. The configuration is substantially the same as the configuration of the above-described sludge reforming process (FIG. 8). The treated water 15 is supplied to the ozone reaction tank 2. Organic matter is treated in the ozone reaction tank 2 and discharged as ozone treated water 16.
Japanese Patent No. 2973761

Ozone is an effective means for reforming sludge and treating organic substances in water because of its strong chemical oxidation action. However, since it is expensive, has large facilities, and consumes a large amount of power, it is desirable to improve contact efficiency with the ozonized gas, reaction efficiency, and consumption efficiency, and suppress wasteful consumption of ozone as much as possible.
Regarding sludge reforming, the conventional sludge reforming equipment only diffuses the ozonized gas supplied from the ozone generator into the sludge to make contact and reaction, so the sludge size and sludge Depending on the nature of the sludge, such as floc and quality, there is a situation where ozone does not come into contact or react efficiently, and the increase in ozone consumption causes an increase in equipment size and cost. Moreover, since the ozone contact / reaction tower becomes large, the dissolution method using aeration is a factor causing the above problem.
Similarly, in the treatment of organic substances in water, it is important to improve the contact / reaction efficiency, and a large amount of ozone is required to inactivate protozoa having spores such as Cryptosporidium. The same applies to the case where treatment is performed by injecting an oxidizing agent other than ozone.
The present invention has been made in view of such problems, and incorporates means having a physical action and improves contact efficiency with ozone and other oxidizing agents to reduce ozone and oxidizing agent consumption. An object is to provide a small and inexpensive sewage treatment apparatus.

In order to solve the above problem , according to one aspect, the present invention provides an ozone dissolving means for dissolving ozone injected from an ozone generator into treated water containing organic treated sludge, dissolved ozone and treatment An ozone reaction tank for reacting target organic substances for a certain period of time and separating undissolved ozone gas from ozone treated water; and an exhaust ozone decomposing apparatus for decomposing and detoxifying the undissolved ozone gas, and modifying the treated sludge. In the sewage treatment apparatus, the cavitation generator is provided in series with the preceding stage of the ozone dissolving means, and the ozone dissolving means is an ejector for mixing and dissolving the ozone.
According to another aspect, the present invention provides an introduction line branched from a sludge extraction line of a sedimentation pond from which treated water containing organic treated sludge is discharged, and injected into the introduction line from an ozone generator. An ozone dissolving means for dissolving the ozone, an ozone reaction tank for reacting ozone dissolved in the water to be treated and organic matter to be treated for a certain period of time and separating undissolved ozone gas from ozone treated water, and decomposing the undissolved ozone gas. In the sewage treatment apparatus having a waste ozone decomposing apparatus for detoxifying and refining the treated sludge and returning it to the biological reaction tank, a part of the treated sludge discharged from the ozone reaction tank is branched and A circulation line for circulation to the introduction line; and a cavitation generator in series with the preceding stage of the ozone dissolution means of the circulation line, wherein the ozone dissolution means It is obtained by the ejector for mixing and dissolving.
According to another aspect, the present invention provides an introduction line branched from a sludge extraction line of a sedimentation pond from which treated water containing organic treated sludge is discharged, and injected into the introduction line from an ozone generator. Ozone dissolving means that dissolves the ozone, ozone reaction tank that reacts ozone dissolved in water and organic matter to be treated for a certain period of time and separates undissolved ozone gas from ozone treated water, and decomposes and detoxifies the undissolved ozone gas And a waste water treatment apparatus for reforming the treated sludge and returning it to the biological reaction tank, wherein a cavitation generator is provided in series with the preceding stage of the ozone dissolving means of the introduction line. The ozone dissolving means is an ejector for mixing and dissolving the ozone.
According to another aspect, the present invention provides an introduction line branched from a sludge extraction line of a sedimentation basin from which treated water containing organic treated sludge is discharged, and an oxidant is injected into the introduction line. In the sewage treatment apparatus that has an oxidant injection device, an oxidation reaction tank that reacts the oxidant dissolved in water and the organic substance to be treated for a certain period of time, reforms the treated sludge and returns it to the biological reaction tank, A circulation line for branching a part of the treated sludge discharged from the oxidation reaction tank and circulating it to the introduction line, a cavitation generator in the circulation line, and the oxidant in series with the subsequent stage of the cavitation generator It is provided with an ejector that sucks and mixes and dissolves in the treated sludge.
According to another aspect, the present invention provides an ozone dissolving means for dissolving ozone injected from an ozone generator into water to be treated containing organic matter, and reacting ozone dissolved in the sewage with the organic matter to be treated for a certain period of time. In a sewage treatment apparatus having an ozone reaction tank that separates undissolved ozone gas from ozone treated water and a waste ozone decomposition apparatus that decomposes and detoxifies the undissolved ozone gas, in series with the preceding stage of the ozone dissolving means A cavitation generator is provided, and the ozone dissolving means is an ejector for mixing and dissolving the ozone.
According to another aspect, the present invention provides an ozone dissolving means for dissolving ozone injected from an ozone generator into water to be treated containing organic matter, and reacting ozone dissolved in the sewage with the organic matter to be treated for a certain period of time. In a wastewater treatment apparatus having an ozone reaction tank for separating undissolved ozone gas from ozone treated water and an exhaust ozone decomposing apparatus for decomposing and detoxifying the undissolved ozone gas, ozone treatment discharged from the ozone reaction tank A circulation line for branching a part of water and circulating it to the introduction line, and a cavitation generator in series with the preceding stage of the ozone dissolution means of the circulation line are provided, and the ozone dissolution means mixes and dissolves the ozone Ejector.
Further, the inside of the cavitation generator and the ejector are both orifice-shaped, the orifices have different diameters, the cavitation generator has a small diameter, the ejector has a large diameter, and the front and back of the cavitation generator The operation may be performed in a range where the differential pressure is 0.1 to 1.5 MPa and the differential pressure before and after the ejector is 0.05 to 0.2 MPa .
Further, hydrogen peroxide as the oxidant may be a fluid obtained by adding halogen-based oxidizing agents or metal catalyst.
Moreover, you may provide the mixing and stirring machine which disperse | distributes the floc-like to-be-processed sludge or organic substance from which a property differs in the upstream of the said introduction line, and mixes and stirs .
Moreover, you may provide the partition which forms an extrusion flow inside the said ozone reaction tank .
Further, a pressurizing pump for circulating the treated sludge may be provided in the circulation line, and the pressurizing pump may be controlled according to the measured viscosity of the viscosity measuring means installed at the subsequent stage .
In addition, each component device may be unitized by function .
In addition, each component device may be arranged on one base .

(1) By arranging the cavitation generator in the front stage and the ejector in series in the rear stage, a stable and high degree of vacuum can be obtained in the sealed space inside the cavitation generator, and it is powerful in the liquid containing sludge. Cavitation with physical strength occurs. Thereby, the sludge cells passing through the space are crushed and finely decomposed, and the viscosity is lowered. That is, the contact area is increased by finely decomposing sludge cells, and the effect of increasing the contact / reaction efficiency with ozone injected later is obtained due to the synergistic effect of decreasing the viscosity. Thereafter, ozone is injected and mixed by the ejector, and contact and reaction with ozone is performed with high efficiency, and sludge is effectively reformed by the strong chemical oxidation action of ozone.
Further, by arranging the cavitation generator and the ejector in series on the same line, the water to be treated is pumped by the same pressurizing pump, so that the device is simple and compact.
(2) By providing the circulation line, the sludge is greatly improved in contact efficiency with ozone, so that the ozone generator can be downsized and the cost can be reduced.
By providing the cavitation generator and the ejector, the sludge is broken down finely as the sludge cells are crushed and broken down by the powerful physical action of cavitation before the ozone treatment. Thereafter, the sludge is effectively reformed by the strong chemical oxidation of ozone.
(3) By providing the cavitation generator and the ejector, the sludge is crushed and finely decomposed by the strong physical action of cavitation before the ozone treatment, and the viscosity is lowered. Thereafter, the sludge is effectively reformed by the strong chemical oxidation of ozone.
(4) By providing a circulation line, the contact and reaction efficiency of sludge with an oxidant is greatly improved.
Further, by providing the cavitation generator and the ejector, the sludge is broken down finely by the sludge cells being crushed and broken down by the strong physical action of cavitation before the contact with the oxidizing agent, and the viscosity is lowered. Thereafter, the sludge is effectively modified by the chemical oxidation action by the oxidizing agent. Thus, the contact efficiency with the oxidant is greatly improved, and the required amount of oxidant is greatly reduced due to a synergistic effect with the physical action of cavitation. Furthermore, since the oxidizer is automatically sucked by the ejector and injected into the sludge or water to be treated and mixed efficiently, equipment such as an injection pump can be omitted, reducing the size and cost of the apparatus. It becomes possible.
(5) In the sewage treatment, floc-like organic substances and outer shell cells of microorganisms are crushed by cavitation and finely decomposed and effectively treated with ozone.
(6) By setting the orifices to have different diameters, the cavitation generator to have a small diameter, the ejector to have a large diameter, and the differential pressure before and after the cavitation generator to be 0.1 to 1.5 MPa. In addition, physical sludge reforming by cavitation and organic matter flocs or microbial shell cells can be effectively degraded. Moreover, by setting the differential pressure before and after the ejector to be 0.05 to 0.2 MPa, it is possible to efficiently inject and dissolve ozone and oxidant.
(7) By making the oxidizing agent a fluid to which hydrogen peroxide, a halogen-based oxidizing agent, or a metal catalyst is added, sludge reforming or organic matter can be oxidized and decomposed easily and efficiently.
(8) Since the ozone reaction efficiency is improved and the treatment can be performed in a short time by the structure having the partition wall inside the ozone reaction tank and forming the extrusion flow, the ozone reaction tank can be greatly downsized.
(9) When mixing sludges with different properties such as initial settling sludge and return sludge, or when sludge lumps or floc-like organic matter flows in, the processing performance is improved. It can contribute to stabilization.
(10) Power consumption of the pressure pump can be optimally controlled by installing a viscosity measurement means and controlling the amount of water and the degree of pressurization by the pressure pump according to the measured viscosity. Can do.
(11) Unitization according to function or placement on a single base enables production at a manufacturing plant and labor saving on installation work at the site, thus reducing introduction costs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a sewage treatment system in which the sewage treatment apparatus of the present invention is incorporated. In the figure, 24 is a sludge reformer. Hereinafter, the same functions are denoted by the same reference numerals, and thus the description of the above functions is omitted.
The configuration of the sludge reforming device 24 is shown in FIG. FIG. 2 is a schematic view of a sludge reforming apparatus showing Example 1 of the present invention. In the figure, 9 is a mixing / stirring machine, 10 is a pressure pump, 11 is a cavitation generator, 12 is an ejector, 13 is a partition, and 14 is a viscosity measuring means. Reference numeral 17 denotes an introduction line for introducing the treated sludge 1, and 18 denotes a circulation line which branches from the introduction line 17 and circulates again to the introduction line 17.
The present invention is different from Patent Document 1 in that a pressure pump, a cavitation generator, an ozone generator, and an ejector that mixes and dissolves ozone generated by the ozone generator in the sludge are subjected to the same sludge circulation reforming treatment. The ozone reaction tank is arranged in the system and has a structure that has a partition wall inside the tower to form an extrusion flow, and is equipped with a mixing / stirring machine that disperses treated sludge or sludge with different properties and performs mixing / stirring. That is. In addition, operation is performed in a range where the differential pressure before and after the cavitation generator is 0.1 to 1.5 MPa and the differential pressure before and after the ejector is 0.05 to 0.2 MPa, and a viscosity measuring means is installed to adjust the measured viscosity. Accordingly, the amount of water and the degree of pressurization by the pressurization pump can be controlled. Furthermore, the ozone generator, the ozone reaction tank, the waste ozone decomposition device, the mixing / stirring machine, and the sludge circulation reforming treatment line are unitized by function or arranged on one base.

Next, the operation of this embodiment will be described.
(1) Firstly, the treated sludge 1 with different properties such as primary sludge and surplus sludge is uniformly mixed by the mixer / stirrer 9 and the sludge mass that is formed by collecting sludge into a large lump is dispersed and evenly distributed. It becomes.
(2) The treated sludge extracted from the ozone reaction tank 2 and pressurized by the pressure pump 10 is introduced into the cavitation generator 11. The inside of the cavitation generator has an orifice structure, and cavitation occurs in the liquid because the treated sludge is in a vacuum state when passing through the rapidly contracted portion. At this time, as shown in FIG. 3, the components of the sludge and the fibrous structure combined in a floc form are subdivided and equalized by receiving a physical impact force by cavitation and contact. At the same time, the cell wall and cell membrane of the sludge are destroyed, and intracellular enzymes are eluted and solubilized. Solubilization also reduces the viscosity of the liquid. The optimum differential pressure (P ₁ -P ₂ ) before and after the cavitation generator varies depending on the properties and viscosity of the sludge to be treated, and is in the range of 0.1 to 1.5 MPa depending on the target conditions.
(3) Next, the treated sludge is introduced into the ejector 12 and mixed with the ozonized gas 4 supplied from the ozone generator 3. Here, it comes into contact with ozone, which has a strong oxidizing power, and is chemically decomposed to be easily biodegradable. By setting the optimum differential pressure before and after the ejector (P ₂ -P ₃ ) within a range of 0.05 to 0.2 MPa, efficient operation can be performed.
(4) Then, it is returned to the ozone reaction tank 2. When the tower has a cylindrical shape, a cylindrical partition wall 13 is provided inside, and the mixed fluid of the sludge to be treated and the ozonized gas rises while rotating around the outer periphery, and after the gas-liquid separation from the exhausted ozone gas, the partition wall An extrusion flow that descends inward is formed. Thereby, since high concentration ozone acts on sludge effectively, reaction time is shortened, As a result, size reduction of a tower is realizable. The exhaust ozone gas is detoxified by the exhaust ozone decomposition device 7.
Moreover, the intensity of cavitation can be changed by controlling the operation output of the pressurizing pump. That is, the on-line viscosity measuring means 14 such as a viscometer is installed in any one of the sludge circulation reforming treatment systems, and the reforming is performed so that the viscosity becomes constant by operating the operation output of the pressure pump according to the measured viscosity. Can control sludge viscosity. This enables efficient operation of the pressurizing pump.
Furthermore, efficient operation can be realized by optimizing the differential pressure before and after the cavitation generator and ejector and controlling the operation of the pressurizing pump by constant viscosity control.

FIG. 4 is an explanatory view showing the configuration of the sludge reforming apparatus showing Embodiment 2 of the present invention.
In the first embodiment, the circulation line 18 is provided, and the pressurizing pump 10, the cavitation generator 11, the ejector 12, and the like are disposed on the circulation line 18. In the present embodiment, these devices are disposed on the introduction line 17.
Depending on the properties of the sludge, even with such a configuration, it is possible to obtain substantially the same effect as in the first embodiment, and the configuration of the treatment line can be simplified.

FIG. 5 is an explanatory view of a sludge reforming apparatus showing Example 3 of the present invention. This embodiment is an apparatus for sludge reforming using an oxidizing agent instead of ozone. In the figure, 22 is an oxidation reaction tank, and 23 is an oxidant injection device. A fluid to which hydrogen peroxide, a halogen-based oxidant, or a metal catalyst is added is used as the oxidant.
The reformed sludge 8 treated in the oxidation reaction tank 22 is returned to the biological reaction tank 20, but a part of the reformed sludge 8 is branched into a circulation line 18, and the pressure pump 10 is used as in the first embodiment. The cavitation generator 11, the ejector 12, etc. are arranged and processed.
Since the oxidizer is automatically sucked by the ejector and injected into sludge or water to be treated and mixed efficiently, equipment such as an injection pump can be omitted, contributing to downsizing of the apparatus and cost reduction. .
With such a configuration, it is possible to obtain substantially the same effect as in the first embodiment.

FIG. 6 is an explanatory diagram of a sewage treatment apparatus showing Embodiment 4 of the present invention. The sewage treatment apparatus of the present embodiment performs an organic matter treatment in the sewage, and the configuration is substantially the same as that of the second embodiment (FIG. 4). is there. In the figure, 15 is treated water, and 16 is treated water.
The difference between the present invention and Patent Document 1 is the same as described above. The difference from the above is that the treated water 15 is in the same system in the order of the pressure pump 10 → the cavitation generator 11 → the ejector 12 → the ozone reaction tank 2. This is the part that is pumped but not circulated.
Next, since the operation of the present embodiment is almost the same as that of the first embodiment, the description will be simplified.
The treated water 15 pressurized by the pressure pump 10 is introduced into the cavitation generator 11.
At this time, floc-like organic components and bacteria present in the water are broken down into fine pieces under physical impact by contact with cavitation. In particular, for spore bacteria such as Bacillus that are highly resistant to chemicals such as ozone and other oxidizing agents, the spore cells are destroyed by contact with cavitation. Next, it is introduced into the ejector 12, mixed with the ozonized gas 4 supplied from the ozone generator 3, further chemically decomposed by reaction with ozone having a strong oxidizing power, and bacteria are killed. Clean treated water 16 will be obtained.

  In this way, by incorporating physical treatment by cavitation and chemical treatment by ozone into the same circulatory system, or by constructing them step-by-step in the same pipe, decomposition and possible at the cellular level due to the physical action of cavitation. It is possible to effectively perform solubilization and decomposition at the molecular level by the chemical action of ozone having a strong oxidizing power. Also, during ozone treatment, wasteful consumption of ozone is suppressed by improving the contact efficiency and reaction efficiency between sludge or organic matter in the water to be treated and ozonized gas, so the ozone generator can be downsized, A small and inexpensive sewage treatment apparatus can be provided.

FIG. 7 is an explanatory diagram of a sludge reforming apparatus showing Example 5 of the present invention. The present embodiment has a configuration substantially equivalent to that of the first embodiment (FIG. 2).
That is, an ozone reaction tank is provided in the introduction line into which the water to be treated is introduced, and a circulation line is provided to circulate a part of the ozone treated water after the ozone reaction to the introduction line again. A device 11, an ejector 12 and the like are arranged.
With this configuration, organic components in wastewater and bacteria present in water can be efficiently removed as in Example 4.

Since the sewage treatment apparatus of the present invention efficiently reforms organic sludge and easily biodegrades it, in general sewage treatment using microorganisms for removing organic matter such as public sewage and industrial wastewater such as chemical factories and food factories. It is also possible to apply methane gas through an anaerobic digestion process of sludge and effectively use it as a biomass resource and to introduce it into facilities for the purpose of reducing sludge associated therewith.
It is also effective against bacteria with strong ozone resistance that were difficult to remove by ozone alone treatment, so it can be applied to inactivation of Cryptosporidium and sterilization treatment of ballast water, which has been regarded as a problem in recent years. is there.

The block diagram which shows the sewage treatment system using the sewage treatment apparatus of this invention The block diagram of the sludge processing apparatus which shows Example 1 of this invention The schematic diagram which shows the state of the sludge before and behind modification | reformation by Example 1 The block diagram of the sludge processing apparatus which shows Example 2 of this invention The block diagram of the sludge processing apparatus which shows Example 3 of this invention The block diagram of the sewage treatment apparatus which shows Example 4 of this invention. The block diagram of the sewage treatment apparatus which shows Example 5 of this invention Schematic showing a conventional sludge reformer Schematic showing conventional sewage treatment equipment

Explanation of symbols

1 Pulled sludge (excess sludge)
1a Sludge to be treated 2 Ozone reaction tank 3 Ozone generator 4 Ozonized gas 5 Ozone dissolving means 6 Waste ozone gas 7 Waste ozone decomposition device 8 Reformed sludge 9 Mixing / stirring machine
10 Pressurizing pump
11 Cavitation generator
12 Ejector
13 Bulkhead
14 Viscosity measuring means
15 treated water
16 treated water
17 Introduction line
18 Circulation line
19 Oxygen supply blower
20 Bioreactor
21 Settling pond
22 Oxidant reaction tank
23 Oxidant injector
24 Sludge reformer

Claims (4)

A part of the extracted sludge withdrawn from the sedimentation basin is treated as sludge, and an oxidation reaction tank that oxidizes the treated sludge with an oxidizing agent;
  An introduction line connected to the front stage of the oxidation reaction tank and introducing the treated sludge into the oxidation reaction tank;
  A circulation line connected to the subsequent stage of the oxidation reaction tank and circulating a part of the sludge oxidized in the oxidation reaction tank to the introduction line;
  A cavitation generator disposed in the circulation line and having a water passage portion having an orifice structure;
  An ejector disposed downstream of the cavitation generator in the circulation line for mixing and dissolving the oxidant;
With
  The diameter of the orifice of the cavitation generator is smaller than the diameter of the orifice of the ejector so that the differential pressure before and after the cavitation generator is larger than the differential pressure before and after the ejector. Sewage treatment equipment characterized by. The differential pressure before and after the cavitation generator when the differential pressure before and after the cavitation generator is 0.1 to 1.5 MPa and the differential pressure before and after the ejector is 0.05 to 0.2 MPa. The sewage treatment apparatus according to claim 1, wherein the diameter of the orifice of the cavitation generator and the diameter of the orifice of the ejector are set so as to increase. In the circulation line, one pressurizing pump is disposed in front of the cavitation generator, and a part of the oxidized sludge is pumped to the cavitation generator and the ejector by the one pressurizing pump. The sewage treatment apparatus according to claim 1 or 2, wherein The sewage treatment apparatus according to any one of claims 1 to 3, wherein the oxidizing agent is ozone.

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