JPH10175000A - Method and apparatus for sludge ozonization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for ozonization with higher concentration by inactivating anaerobic bacteria primarily responsible for sludge decay by using ozone. SOLUTION: In a treatment where sludge is allowed to flow in an ozonization reaction chamber 1 so that ozone gas diffuses inside the sludge, viscosities of sludge ozonization-processed and a viscosity of sludge to be ozonization- processed are measured by each viscometer 6a, and a controller 7 obtains an ozone injection rate based on the viscosity of the sludge ozonization-processed and a viscosity of a predetermined control target value, and send a control output signal 7a to an ozonizer 3 and determines the optimum ozone-injecting volume. In addition to the above operation, a concentration meter for measuring concentration of sludge drawn out from the ozonization reaction chamber 1 is provided and a viscosity ratio is calculated from the viscosity of the sludge to be ozonization-processed, and the viscosity of the control target value and the ozone injection rate obtained by the viscosity and the concentration of the sludge is corrected by the viscosity ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for efficiently concentrating sludge by performing ozone treatment. More particularly, the present invention relates to an anaerobic bacterium which is a main cause of sludge decay in intensive treatment. TECHNICAL FIELD The present invention relates to an ozone treatment method and a treatment apparatus that can increase the concentration of sludge by inactivating the sludge using the method.

[0002]

2. Description of the Related Art The concentration of organic matter in sewage flowing into a sewage treatment plant has increased with the recent improvement of living standards and the transition of sewage elimination systems and the progress of maintenance. As a result, the concentration property is reduced, which causes a reduction in the treatment efficiency of the subsequent sludge treatment system and an increase in the organic matter load on the water treatment system due to the return water.

[0003] Further, with the spread of sewers, the amount of treated sewage has been increasing year by year, and the amount of generated sludge has also increased at almost the same rate (see the 1992 Sewerage Yearbook, published by Water Supply Industry Newspaper). This treatment of sludge poses a serious problem not only in large cities with large restrictions on disposal sites, but also in small and medium cities.

On the other hand, surplus sludge generated in a water treatment facility in an urban sewage treatment plant or raw sludge initially generated in a sedimentation basin is drawn out of the system of the water treatment facility, transported to the sludge treatment facility, and concentrated, digested, and digested. Final disposal is performed through processes such as dehydration and incineration. Especially in large metropolitan areas, multiple sewage treatment plants are often in close proximity due to factors such as population concentration, and the sludge generated at each of these sewage treatment plants should be concentrated in one place to carry out sewage treatment. Thereby, the sludge treatment cost can be reduced.

[0005] Various methods of the above-mentioned sludge treatment will be described with reference to Fig. 12. (1) A method of concentrating raw sludge, a final disposal after digestion or a final disposal through solar drying, and (2) a method of concentrating raw sludge. Adjustment or digestion afterwards, mechanical dehydration after adjustment, composting and final disposal, (3)
In the method, the raw sludge is adjusted after concentration, or digested, mechanically dehydrated after adjustment, final disposal or drying, incineration, and then final disposal. (4) The raw sludge is concentrated, heat-treated, mechanically dehydrated, and incinerated. The final disposal method, (5) is a method for concentrating raw sludge, mechanically dewatering after wet oxidation, and then final disposal (sewerage facility design guidelines and commentary-page 423,
1984 edition, published by the Japan Sewerage Association).

[0006] The digestion process in the case of incineration of the above-mentioned (3) has advantages such as a reduction in the size of the facility due to a reduction in the amount of sludge, the use of digestion gas, and the effect of storing the sludge. There are problems such as the effect of the desorbed liquid on the facility, the decrease in the amount of heat generated by sludge, and the complexity of the site and facilities.

In the method (4), the heat treatment improves the filterability and does not use any chemicals for dewatering the sludge.
Although the method has the advantage of reducing the number of dewatered cakes as compared with the method (3), heating energy is required, so that waste heat of sludge incineration is used, the BOD of the filtrate is high, and strict operation management is required.

The above method (5) involves burning organic matter in a liquid state under high temperature and high pressure by a wet oxidation method, and is used as an alternative to the digestion and incineration processes. Since the temperature and pressure are higher than in the method (4), the maintenance is strict.

[0009] In order to carry out the intensive treatment of sludge, it is necessary to transport the sludge generated in each treatment plant to a centralized sludge treatment plant.
As the transportation method, truck transportation, ship transportation, pipe transportation and the like can be considered. The advantages of intensive treatment include the economies of scale of sludge treatment facilities, the convergence of environmental measures, the efficiency of energy recovery, the reduction of maintenance and management costs, and the improvement of sludge recycling. When a mud pipe is used, it can be broadly divided into a naturally flowing section and a pumping section using a pump. It takes about 24 hours to send the sludge from the farthest sewage treatment plant to the sludge treatment facility.

[0010] The quality of the operation of the concentrator affects not only the subsequent sludge treatment system but also the water treatment system. For example, since the amount of sludge is greatly affected by the water content, concentrating and reducing the amount of sludge has the effect of saving the capacity of the facility in the subsequent process. 99% water content
When the sludge is concentrated to a water content of 96%, the sludge amount is reduced to 1/4. In particular, when the concentration is not sufficiently performed, a large amount of heat is required for digestion treatment, which affects the number of digestion days. Furthermore, the dewatering property when directly dewatering the concentrated sludge deteriorates.

When the solids recovery rate in the sludge concentration tank is low, a large amount of ss (suspended matter) component is contained in the separated liquid,
May affect water treatment facilities. There are gravity type, floating type and centrifugal concentration type for sludge concentration. Generally, gravity type is frequently used, but recently the sedimentation and concentration of sludge have become worse, especially in the summer, concentrated sludge. The solids recovery rate may decrease due to a decrease in the concentration of the sludge or a part of the sludge floating. Therefore, it is conceivable to first use a gravity method to separate only the excess sludge by floating or centrifugal concentrating when the sedimentation becomes poor. However, if two types of sludge thickening tanks are provided, the maintenance and management becomes complicated and uneconomical Problem arises.

[0012]

SUMMARY OF THE INVENTION As described above, the sludge in a thickening device progresses due to an increase in the concentration of organic matter in sewage flowing into a sewage treatment plant, and the thickening property is reduced.
There is a problem that the treatment efficiency of the succeeding sludge treatment system is reduced or the organic matter load on the water treatment system due to the return water is increased. In the case of sludge consolidation treatment, when pipes are transported for sewage sludge, the inside of the pipe becomes full in the pumping section during transportation, so anaerobic microorganisms decompose organic matter in sludge that has become anaerobic and decompose sludge. It causes problems such as corrosion of facilities, generation of odor, deterioration of concentration, deterioration of dehydration, and increase of return water load.

To cope with the above, there is a method of inactivating anaerobic microorganisms, which are the main cause of sludge rot, using chemicals such as hydrogen peroxide and sodium hypochlorite. Since the points have not been cleared, they have not yet been put to practical use, and in fact, only means for washing the sludge pipes have been used. (Survey on improvement of the function of gravity concentration tanks by controlling decay of sludge, Japanese sewerage system The Japan Business Development Agency Technical Development Bulletin 1985, Survey on the actual state of sludge property change accompanying sludge transfer and control of decay, Tokyo Metropolitan Sewerage Bureau 1992).

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to improve the concentration of sludge by inactivating anaerobic bacteria, which is a main cause of sludge decay, with ozone. It is an object of the present invention to provide an ozone treatment method and a treatment apparatus capable of performing the above-mentioned steps.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to performing a concentration treatment by flowing sludge into a closed type ozonation reaction tank and dispersing ozone gas into the sludge. In the ozonation of sewage sludge, first, the viscosity of the ozone-treated sludge is measured according to claim 1, and the optimum viscosity is determined based on the viscosity of a preset control target value and the measured viscosity of the ozone-treated sludge. Provided is a sludge ozone treatment method in which an ozone injection rate is calculated by a controller, and drive control of an ozone generator for supplying ozone gas to an ozone treatment reaction tank is performed based on an output of the controller.

According to the present invention, the viscosity of the untreated ozone sludge is measured, and the "viscosity ratio" is determined based on the viscosity of a preset control target value. Is calculated by a controller, and based on the output of the controller, an ozone treatment method for controlling the driving of an ozone generator that supplies ozone gas to the ozone treatment reaction tank is provided. A viscometer for measuring the viscosity of the sludge and a viscometer for measuring the viscosity of the ozone-untreated sludge are provided, and the controller calculates the ratio of the viscosity based on the measured viscosity of the ozone-untreated sludge and the viscosity of the control target value. Is calculated, the ozone injection rate is calculated from the viscosity of the ozone-treated sludge and the viscosity of the control target value, and this ozone injection rate is corrected by the ratio of the previously obtained viscosity. Using ozone treatment method of sludge to perform the drive control of the ozone generator for supplying ozone gas to the ozonation reaction vessel based on the output of the roller.

According to a fourth aspect of the present invention, a viscometer for measuring the viscosity of the ozone-treated sludge, a viscometer for measuring the viscosity of the non-ozone-treated sludge, and a sludge meter for measuring the viscosity of the sludge extracted from the ozone-treated reaction tank are provided in the ozonation reaction tank. A sludge densitometer for measuring the concentration is provided, and the controller calculates a "viscosity ratio" from the measured viscosity of the untreated ozone sludge and the viscosity of the control target value, and calculates the viscosity of the ozone treated sludge and the concentration of the ozone treated sludge. From the above, the ozone injection rate is obtained by calculation, the ozone injection rate is corrected by the previously obtained viscosity ratio, and then the drive control of the ozone generator for supplying the ozone gas to the ozone treatment reaction tank based on the output of the controller. To provide an ozonation method for sludge.

According to a fifth aspect of the present invention, there is provided a closed type ozonation reaction tank, and a contact in which a mixture of sludge and ozone gas is allowed to spontaneously fall from the ozone injection portion through the upper wall of the ozonation reaction tank into the ozone treatment reaction tank. Pipe, a sludge circulation pipe led out from the lower part of the ozonation reaction tank and connected to the ozone injection section, a viscometer for measuring the viscosity of the ozone-untreated sludge and the ozone-treated sludge, and The sludge ozone treatment apparatus is provided with a sludge concentration meter for measuring the concentration of the extracted sludge.

According to the sewage sludge ozonation method and treatment apparatus, as a basic operation, the viscosities of the ozone-treated sludge and / or the non-ozone-treated sludge are measured by the respective viscometers, and the sludge is extracted from the ozonation reaction tank. The sludge concentration is measured by a sludge densitometer, and these measured values are input to the controller. The controller calculates the "viscosity ratio" from the measured viscosity of the untreated ozone sludge and the viscosity of the control target value, and calculates the ozone injection rate from the concentration and the viscosity of the ozone treated sludge by calculation. Is corrected by the previously determined viscosity ratio, and then a control output signal is issued to the ozone generator to determine the optimal amount of injected ozone.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of the method and apparatus for treating ozone of sludge according to the present invention will be described below. There are various methods for treating this sludge depending on the final disposal of the sludge. In this embodiment, the ozone treatment is performed before the concentration to prevent the sludge from being putrefactive, and the process is shifted to the subsequent treatment. That is, the steps are simply described as "sludge ozone treatment", "concentration treatment", "dehydration treatment", "incineration treatment", and "final disposal".

FIG. 1 is a schematic diagram of a sludge treatment system according to a first embodiment of the present invention. First, main components will be described. 1 is a sealed ozone treatment reaction tank, 2 is an ozone injection section, 2a Is a contact pipe fitted through the upper wall of the ozone treatment reaction tank 1, 2b is a sludge circulation pipe, 3 is an ozone generator,
4 is an exhaust ozone treatment device, 5 is a water level adjusting tank, 6a is a viscometer, and 7 is a controller.

According to such a configuration, the sludge is fed to the sludge circulation pipe 2b by the sludge feed pump P _1, the contact tubes 2a ozone gas obtained by the ozone generator 3 from being injected in the sludge by an ozone injection section 2 It falls freely inside and is fed into the ozone treatment reaction tank 1. Ozone gas and sludge come into sufficient contact due to the mixing action at the time of descending. Some of the sludge stored in the ozonation reaction tank 1 is withdrawn from the lower portion of the ozonation reaction vessel 1 by the actuation of the sludge circulation pump P _2, mixed with ozone untreated sludge in the sludge circulation pipe 2b After that, the ozone gas is injected again by the ozone injection unit 2 and sent into the ozone treatment reaction tank 1 from the contact pipe 2a to circulate.

The ozonized liquid is sent to the next step after passing through the water level adjusting tank 5, and the ozone gas discharged without being used for the reaction is decomposed to a reference value or less by the exhausted ozone processing apparatus 4 and then released into the atmosphere. You.

[0024] During the above action, ozonated sludge by the pump P ₃ is measured viscosity is fed into the viscometer 6a, the measured value is input to the controller 7.

The controller 7 calculates the ozone injection rate based on the measured viscosity of the ozonized sludge and the viscosity of a preset control target value, and sends a control output signal 7a to the ozone generator 3. Determine the optimal amount of injected ozone.

According to the sludge treatment system shown in FIG. 1, the sludge fed into the ozonation reaction tank 1 can be continuously ozone-treated. In particular, the ozone gas injected into the contact pipe 2a becomes uniform bubbles due to the balance with the descending sludge liquid flow rate, and then flows down while contacting the sludge, and the mixed liquid of the sludge and the ozone gas flows into the ozone treatment reaction tank 1. By infiltrating deeply into the vicinity of the bottom wall of the tank, the effect of stirring the sludge in the tank is brought about, and the progress of the ozone reaction is promoted.

Hereinafter, various experimental examples which are the basis of this embodiment will be described. First, with respect to a sludge sample obtained from municipal sewage, a change in concentration due to ozone treatment was determined by a sedimentation experiment. This ozone treatment experiment was performed for the purpose of improving the enrichment, and was carried out by a semi-batch method shown in FIG.

That is, the ozone gas obtained by the ozone generator 3 is injected into the sludge by the ozone injection section 2, sent to the ozone treatment reaction tank 1 in a free fall state in the contact pipe 2 a, and stored in the ozone treatment reaction tank 1. has been a part of the sludge withdrawal from the bottom of the ozonation reaction vessel 1 by the drive of the sludge circulation pump P _2, passed through a sludge circulation pipe 2b fed to the ozone injection section 2, the catalyst tube 2a by injecting ozone gas again It is sent to the ozone treatment reaction tank 1 and circulated. The ozone-treated sludge was appropriately sampled from the sampling port 8 and analyzed for viscosity and sludge concentration. One liter of the sampled sludge was used as a sample for a settling experiment described below.

The sedimentation experiment was carried out by placing raw sludge and ozone-treated sludge in 1-liter measuring cylinders and allowing them to stand, and measuring the height of the sludge interface at an appropriate time.

FIG. 3 shows the viscosity (mPa · m) when the ozone injection rate was changed from 0 (mg / l) to 150 (mg / l).
S) shows that the viscosity of the sludge changes depending on the ozone injection rate. The viscosity of raw sludge takes various values, but the viscosity decreases as the ozone injection rate increases.

FIG. 4 shows the relationship between the viscosity immediately after the ozone treatment and the sludge settling rate after 12 hours. The contribution ratio r ² between the viscosity and the sludge settling rate after 12 hours has a high correlation with 0.965. As the viscosity decreases, the sludge settling rate monotonically decreases. From this fact, for example, when it is desired to set the sedimentation interface of the concentration tank to about 40%, ozone treatment may be performed so that the viscosity becomes 7.5 (mPa · S).

The residence time of a general concentration tank is 12 hours, but the residence time of the concentration tank may be shortened depending on the amount of sludge. Even in this case, the interface height of the sludge can be estimated by measuring the viscosity of the sludge immediately after the ozone treatment.

FIG. 5 shows the relationship between the viscosity immediately after the ozone treatment and the sludge settling rate after 6 hours. The contribution ratio r ² between the viscosity and the sludge settling rate after 6 hours has a high correlation with 0.958. As the viscosity decreases, the sedimentation rate of the sludge decreases. Therefore, for example, when it is desired to reduce the interface of the sludge to about 50% after 6 hours, it is understood that ozone treatment should be performed so that the viscosity becomes 6 (mPa · S).

As described with reference to FIG. 3, the viscosity of the sludge takes various values, but when ozone is injected into the sludge, the viscosity decreases at a constant rate. Hereinafter, the value obtained by dividing the viscosity of the sludge subjected to the ozone treatment by the viscosity of the sludge not subjected to the ozone treatment is defined as “viscosity ratio”.

FIG. 6 shows the relationship between the ozone injection rate and the viscosity ratio. The contribution ratio r ² between the ozone injection rate and the viscosity is 0.8.
25, the viscosity ratio decreases with an increase in the ozone injection rate. Therefore, the ratio of the viscosity is calculated from the target viscosity value, and the graph of FIG. 6 can determine the ozone injection rate.

FIG. 7 is a schematic diagram of a sludge treatment system according to a second embodiment of the present invention realized based on the above experimental results.
Since the basic configuration is the same as that of the first embodiment shown in FIG. 1, the same components are denoted by the same reference numerals. In this second embodiment Yes deploying a pump P ₄ and viscometer 6b upstream portion of the sludge supply pump P _1, and inputs the measured value by the viscometer 6b to the controller 7. Other configurations are the same as those of the first embodiment.

[0037] According to the second embodiment, the viscosity of the sludge ozone untreated is first drawn into the pump P ₄ viscometer 6
After being measured by b, the sludge is fed to the sludge circulation pipe 2b by the sludge feed pump P _1, the contact tube 2a ozone gas obtained by the ozone generator 3 from being injected in the sludge by an ozone injection section 2 Is freely dropped and sent into the ozone treatment reaction tank 1 so that the ozone gas and the sludge come into sufficient contact. From the lower part of the ozone treatment reaction tank 1, a sludge circulation pump P
_The sludge extracted with the drive of ₂ is mixed with the untreated ozone sludge in the sludge circulation pipe 2b, and then the ozone gas is injected again in the ozone injection section 2 and sent into the ozone treatment reaction tank 1 from the contact pipe 2a. Circulate.

The controller 7 calculates a "viscosity ratio" based on the measured viscosity of the untreated ozone sludge and the viscosity of a preset control target value, and calculates the ozone injection rate from this value. The control output signal 7a is sent to the ozone generator 3 to determine the optimal amount of injected ozone. The second embodiment is characterized in that the ozone treatment can be performed in consideration of the fluctuation state of the viscosity of the raw sludge.

On the other hand, the viscosity tends to change depending on the sludge concentration (TS). FIG. 8 shows the relationship between the ozone injection rate per 1 g TS (ozone injection rate / TS) (mg / g) and the viscosity ratio, and the contribution ratio r ² between the ozone injection rate / TS and the viscosity ratio. Is higher than the correlation between 0.945 and the ratio of the ozone injection rate and the viscosity (FIG. 6). Therefore, the use of the ozone injection rate / TS is more accurate than the case where the ozone injection rate is used alone. Can be well expressed.

FIG. 9 is a schematic diagram of a sludge treatment system according to a third embodiment of the present invention realized based on the above experimental results.
With in the third embodiment deploying a pump P ₄ and viscometer 6b upstream portion of the sludge supply pump P _1, sludge is withdrawn upstream of the sludge circulation pump P ₂ from the lower side of the ozonation reaction vessel 1 A sludge densitometer 9 for measuring the concentration of the sludge is provided, and the value measured by the viscometer 6b and the value measured by the sludge concentration meter 9 are input to the controller 7. Other configurations are the same as those of the first embodiment.

According to the third embodiment, the viscosity of the sludge not treated with ozone is first drawn out by the pump P _4, and
After being measured by b, the sludge is fed to the sludge circulation pipe 2b by the sludge feed pump P _1, the contact tube 2a ozone gas obtained by the ozone generator 3 from being injected in the sludge by an ozone injection section 2 Is freely dropped and sent into the ozone treatment reaction tank 1 so that the ozone gas and the sludge come into sufficient contact. From the lower part of the ozone treatment reaction tank 1, a sludge circulation pump P
The concentration of the sludge extracted with the drive of ₂ is measured by the sludge concentration meter 9, mixed with the untreated ozone sludge in the sludge circulation pipe 2 b, and then the ozone gas is injected again by the ozone injection section 2, and the contact pipe It is sent from 2a to the ozone treatment reaction tank 1 and circulates.

The controller 7 calculates the "viscosity ratio" from the measured viscosity of the untreated ozone sludge and the viscosity of the control target value, and calculates the ozone injection rate from this value and the concentration of the ozone treated sludge by calculation. The control output signal 7a is sent to the ozone generator 3 to determine the optimal amount of injected ozone.

[0043] Figure 10 is a schematic diagram of a fourth embodiment of the present invention, in this example Yes deploying the pump P ₃ and viscometer 6a to ozonation reaction vessel 1, further preliminary portion of the sludge supply pump P ₁ It is deployed pump P ₄ and viscometer 6b on. The values measured by the viscometers 6a and 6b are input to the controller 7. Other configurations are the same as those of the first embodiment.

In the fourth embodiment, in addition to the feedback control based on the viscosity of the ozone-treated sludge measured by the viscometer 6a, the control is combined with the feedforward control based on the viscosity of the unozone-treated sludge measured by the viscometer 6b. It is a feature. The controller 7 calculates the “viscosity ratio” from the measured viscosity of the untreated ozone sludge and the viscosity of the control target value, and calculates the ozone injection rate from this value, the viscosity of the ozone treated sludge, and the viscosity of the control target value. The ozone injection amount is corrected by the previously calculated viscosity ratio, and then the control output signal 7a is issued to the ozone generator 3 to determine the optimum injection ozone amount.

[0045] Figure 11 is a schematic diagram of a fifth embodiment of the present invention, the pump P to the front portion of the sludge supply pump P ₁ together with this example to deploy pump P ₃ and viscometer 6a to ozonation reaction vessel 1 deployed ₄ and viscometer 6b, it is further deployed sludge concentration meter 9 for measuring the concentration of sludge withdrawn from the lower portion in the ozonation reaction vessel 1 upstream of the sludge circulation pump P _2. Viscometers 6a and 6b and sludge concentration meter 9
Is input to the controller 7. Other configurations are the same as those of the first embodiment.

The fifth embodiment is characterized by a combination of control based on the concentration of raw sludge in addition to the feedback control and the feedforward control. The controller 7 calculates the “viscosity ratio” from the measured viscosity of the untreated ozone sludge and the viscosity of the control target value, and calculates the ozone injection rate from this value, the viscosity of the ozone treated sludge, and the viscosity of the control target value. The ozone injection amount is corrected by the ratio of the viscosity obtained previously and the concentration measured by the sludge densitometer 9, and then the control output signal 7 a is sent to the ozone generator 3 to determine the optimum injection ozone amount. decide.

Summarizing the above results, the following conclusions are obtained. In other words, if the sludge is treated with ozone, the anaerobic bacteria, which are the main cause of sludge decay, are inactivated by ozone treatment, thereby increasing the concentration of the sludge. Trouble can be reduced.

The method of controlling the amount of injected ozone is a method of controlling the ozone injection time (ozone contact time, sludge residence time), a method of controlling the concentration of injected ozone gas, and a method of controlling the flow rate of injected ozone gas.
There are combinations of methods.

[0049]

According to the above-described method and apparatus for treating ozone of sludge according to the present invention, the basic operation is to measure the viscosity of ozone-treated sludge and / or unozone-treated sludge with a viscometer, The concentration of sludge withdrawn from the treatment reaction tank is measured by a sludge concentration meter and input to the controller, and a `` viscosity ratio '' is calculated from the measured viscosity of the ozone-untreated sludge and the viscosity of the control target value,
Calculate the ozone injection rate from the concentration and viscosity of the ozone-treated sludge, correct this ozone injection rate with the previously determined viscosity ratio, and then issue a control output signal to the ozone generator to obtain the optimum injection rate. The amount of ozone can be determined.

In particular, if the sludge is treated with ozone, the concentration property can be improved, and the residence time of the gravity concentration tank can be reduced, so that various troubles caused by sludge decay in the concentration tank can be reduced. In addition, the effect is obtained that the amount of sludge after the concentration tank is reduced and the scale of the treatment facility can be reduced.

Further, the viscosity and concentration of sludge can be continuously measured by a viscometer or a sludge concentration meter, and the amount of ozone can be measured on-line, so that it can be monitored at the same time as the operation and can be treated using an appropriate amount of ozone. Control becomes possible.

Therefore, according to the present invention, the sludge treatment after consolidation can be performed stably while maintaining good sedimentation and thickening properties of sludge due to decay and alteration of sludge.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a sludge treatment system according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an apparatus used for an ozone treatment experiment in the present embodiment.

FIG. 3 is a graph showing a change in viscosity when the ozone injection rate is changed.

FIG. 4 is a graph showing a relationship between viscosity and a sludge settling rate after 12 hours in a settling experiment.

FIG. 5 is a graph showing the relationship between viscosity and sludge settling rate after 6 hours in a settling experiment.

FIG. 6 is a graph showing a relationship between an ozone injection rate and a viscosity ratio.

FIG. 7 is a schematic diagram of a sludge treatment system according to a second embodiment of the present invention.

FIG. 8 is a graph showing a relationship between an ozone injection rate per TS and a viscosity ratio.

FIG. 9 is a schematic diagram of a sludge treatment system according to a third embodiment of the present invention.

FIG. 10 is a schematic diagram of a sludge treatment system according to a fourth embodiment of the present invention.

FIG. 11 is a schematic diagram of a sludge treatment system according to a fifth embodiment of the present invention.

FIG. 12 is a schematic diagram for explaining various methods of conventional sludge treatment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ozone treatment reaction tank 2 ... Ozone injection part 2a ... Contact pipe 2b ... Sludge circulation pipe 3 ... Ozone generator 4 ... Exhaust ozone treatment apparatus 5 ... Water level adjuster 6a, 6b ... Viscometer 7 ... Controller 8 ... Samp rig opening 9 ... Sludge concentration meter

Claims (5)

[Claims] In the ozone treatment of sewage sludge in which sludge flows into a closed type ozonation reaction tank, and the ozone gas is diffused into the sludge to perform the concentration treatment, the viscosity of the ozone-treated sludge is reduced. The controller calculates the optimum ozone injection rate based on the viscosity of the preset control target value and the measured viscosity of the ozone-treated sludge, and outputs the ozone gas to the ozone-treatment reaction tank based on the output of the controller. A method for treating ozone in sludge, comprising controlling the driving of an ozone generator for supplying sludge. 2. The ozone treatment of sewage sludge in which sludge flows into a closed-type ozonation reaction tank and is subjected to concentration treatment by dispersing ozone gas into the sludge. Measure and calculate the "viscosity ratio" based on the viscosity of the preset control target value, calculate the optimum ozone injection rate from the viscosity ratio by the controller, and perform the ozone treatment based on the output of the controller. An ozone treatment method for sludge, comprising controlling the driving of an ozone generator for supplying ozone gas to a reaction tank. 3. The ozone treatment of sewage sludge in which the sludge flows into a closed type ozonation reaction tank and the concentration treatment is performed by dispersing ozone gas into the sludge. A viscometer that measures the viscosity of the ozone-treated sludge and a viscometer that measures the viscosity of the ozone-untreated sludge are provided. The ratio of the viscosity is calculated, the ozone injection rate is obtained by calculation from the viscosity of the ozone-treated sludge and the viscosity of the control target value, and the ozone injection rate is corrected by the previously obtained viscosity ratio before the controller of the controller. An ozone treatment method for sludge, comprising controlling the driving of an ozone generator for supplying ozone gas to an ozone treatment reaction tank based on the output. 4. The ozone treatment of sewage sludge in which the sludge flows into a closed type ozonation reaction tank and the concentration treatment is performed by dispersing ozone gas into the sludge. A viscometer for measuring the viscosity of the ozone-treated sludge, a viscometer for measuring the viscosity of the ozone-untreated sludge, and a sludge concentration meter for measuring the concentration of the sludge withdrawn from the ozonation reactor are provided. The controller calculates a “viscosity ratio” from the viscosity of the untreated sludge and the viscosity of the control target value, and calculates the ozone injection rate from the viscosity of the ozone-treated sludge and the concentration of the ozone-treated sludge. Is corrected by the previously determined viscosity ratio, and then the drive control of the ozone generator for supplying ozone gas to the ozone treatment reaction tank is performed based on the output of the controller. Ozone treatment method of sludge. 5. A closed ozone treatment reaction tank, a contact tube for allowing a mixture of sludge and ozone gas to drop naturally from an ozone injection section through an upper wall of the ozone treatment reaction tank into the ozone treatment reaction tank, A sludge circulation pipe led out from the lower side of the treatment reaction tank and connected to the ozone injection section, a viscometer for measuring the viscosities of the ozone-untreated sludge and the ozone-treated sludge,
A sludge ozone treatment apparatus comprising a sludge concentration meter for measuring the concentration of sludge drawn from an ozone treatment reaction tank.