WO2010113846A1 - 汚泥脱水方法、電気浸透脱水方法及び装置 - Google Patents
汚泥脱水方法、電気浸透脱水方法及び装置 Download PDFInfo
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- WO2010113846A1 WO2010113846A1 PCT/JP2010/055525 JP2010055525W WO2010113846A1 WO 2010113846 A1 WO2010113846 A1 WO 2010113846A1 JP 2010055525 W JP2010055525 W JP 2010055525W WO 2010113846 A1 WO2010113846 A1 WO 2010113846A1
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- sludge
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- electroosmotic
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
- B01D61/56—Electro-osmotic dewatering
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/15—Treatment of sludge; Devices therefor by de-watering, drying or thickening by treatment with electric, magnetic or electromagnetic fields; by treatment with ultrasonic waves
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/58—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element
- B01D33/62—Handling the filter cake in the filter for purposes other than for regenerating the filter cake remaining on the filtering element for drying
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/025—Reverse osmosis; Hyperfiltration
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
- C02F11/123—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using belt or band filters
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2311/00—Details relating to membrane separation process operations and control
- B01D2311/04—Specific process operations in the feed stream; Feed pretreatment
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
- C02F1/4698—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electro-osmosis
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/002—Construction details of the apparatus
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/46—Apparatus for electrochemical processes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/20—Sludge processing
Definitions
- the present invention relates to a method of dewatering sludge generated in biological treatment processes of various industrial wastewater with an electroosmotic dehydrator, and in particular, concentrated salt that has been disposed of in the past for tempering sludge before electroosmotic dehydration.
- the present invention relates to a method for industrially advantageously obtaining dehydrated sludge having a low moisture content.
- the present invention also relates to an electroosmotic dehydration method and apparatus for dehydrating hydrated materials such as wastewater biologically treated sludge and clean water sludge.
- Electro-osmotic dehydration is well known as a method for dehydrating hydrated substances such as sludge generated during biological treatment of wastewater (Patent Documents 1 to 5, Non-Patent Document 1).
- the electroosmotic dewatering device of Patent Document 1 is configured to electrolyze and dewater sludge between an endless rotating lower filter belt (cathode) and an endless rotating upper press belt (anode). .
- the electroosmotic dewatering device of Patent Document 2 is configured such that an electrode drum as an anode is disposed separately from the upper press belt, and the upper and lower belts are clamped by this electrode drum.
- the electroosmotic dewatering device of Patent Document 3 supplies sludge onto a conveyor belt that rotates endlessly, and sandwiches a hydrated material between a cathode plate below the conveyor belt and an anode unit above the conveyor belt.
- the electroosmosis dehydration is performed by passing an electric current.
- a plurality of anode units are arranged in the conveyor moving direction.
- a horizontal anode plate is installed on the bottom surface of each anode unit. The anode plate can be pushed down by an air cylinder and can be pulled up by a spring.
- the conveyor moves the hydrated material by one span (anode unit installation interval) with the anode plate raised.
- a two-leaf filter cloth is disposed between a pair of left and right filter plates having both poles. Sludge is supplied between the filter cloths, sandwiched between the filter cloths, and energized between the electrodes, whereby the sludge is subjected to electroosmotic dehydration. After the treatment, the filter plate is separated, and then the filter cloths are separated from each other to remove the dehydrated product.
- the dehydration amount is proportional to the energization amount, and therefore, when the electrical conductivity of the sludge is increased, the moisture content of the dewatered cake tends to decrease.
- A) The pH and electrical conductivity of the cake after dehydration are adjusted by collecting the dehydrated filtrate and adding it to the sludge before dehydration (Patent Document 1).
- An electrolyte such as sodium chloride, sodium sulfate, or sodium carbonate is added to the sludge (Patent Document 4).
- a conductive activator is added to the sludge (Patent Document 2. However, Patent Document 2 does not specifically describe what the conductive activator is).
- Sludge generated in the biological treatment process of various industrial wastewater contains a lot of moisture, and is decontaminated and disposed of as waste.
- mechanical dehydration devices such as pressure dehydrators such as belt presses and filter presses and centrifugal dehydrators have been used for sludge dewatering.
- some of these sludges fibers and Except for sludge containing a lot of easily dehydrated components such as sand, the water content cannot be lowered sufficiently, and the water content of the obtained dehydrated sludge is limited to about 80%.
- various wastewater treatment facilities include a concentration facility for concentrating and separating salts in the wastewater.
- the wastewater is biologically treated by activated sludge treatment or the like, and a reverse osmosis membrane separation device or an evaporator (evaporator / concentrator) is used to reuse the obtained biologically treated water as ultrapure water.
- a reverse osmosis membrane separation device or an evaporator evaporator / concentrator
- evaporator / concentrator evaporator / concentrator
- salts such as sodium sulfate, sodium nitrate and sodium chloride derived from biological metabolites, sodium hydroxide for pH adjustment, polyferric sulfate, etc.
- industrial waste industrial waste
- it is discharged outside the system and disposed of, and the separated water is taken out as treated water.
- the present invention solves the above-mentioned conventional problems, reduces the cost of chemicals when dewatering sludge generated in the biological treatment process of various industrial wastewater with an electroosmotic dehydrator, and also provides a dissolution tank, a heating facility, etc. It is a first object to provide a method for performing an efficient electroosmotic dehydration treatment without requiring additional equipment or additional energy.
- the present invention relates to an electroosmotic dehydration method and apparatus for increasing the electrical conductivity of sludge by adding an electrolyte or a dehydrated filtrate to a treated water-containing material and reducing the water content of the dehydrated material.
- a second object is to provide an electroosmotic dehydration method and apparatus that can be further efficiently reduced.
- the sludge dewatering method is a method of dewatering sludge with an electroosmotic dehydrator, wherein the concentrated salt discharged from a wastewater treatment facility is added to the sludge and then dewatered with the electroosmotic dewaterer.
- the sludge dewatering method of the second aspect is characterized in that, in the first aspect, the amount of the concentrated salt added to the sludge is 1% by weight or more.
- the sludge dewatering method according to the third aspect is the electrosmosis method according to the first or second aspect, wherein the sludge is subjected to mechanical dehydration prior to dehydration with an electroosmosis dehydrator, and the concentrated salt is added to the obtained dewatered cake. It is characterized by dehydrating with a dehydrator.
- the sludge dewatering method of the fourth aspect is characterized in that, in the third aspect, the moisture content of the dewatered cake is 70 to 90%.
- the concentrated salt is a concentrated salt obtained by concentrating biological treated water as wastewater by reverse osmosis membrane separation treatment or evaporation concentration. It is characterized by.
- the sludge dewatering method according to the sixth aspect is characterized in that, in the fifth aspect, the dehydrated filtrate obtained by the dewatering treatment by the electroosmotic dewatering device is returned to the biological treatment tank for the waste water for treatment.
- the sludge is subjected to the electrical conductivity of sludge by adding concentrated salt discharged from wastewater treatment facilities conventionally disposed of to industrial sludge to be subjected to electroosmotic dewatering.
- the energization efficiency can be improved to increase the dewatering efficiency by the electroosmosis dewatering device, and the water content of the dewatered sludge obtained can be reduced.
- This concentrated salt is generated in a wastewater treatment facility and has been conventionally disposed of as industrial waste. There is no problem of a new increase in chemical cost due to the addition of this concentrated salt to sludge. Moreover, it is possible to reduce the amount of industrial waste by effectively using concentrated salt. Further, since this concentrated salt is in the form of a slurry, it can be uniformly dispersed even if it is directly added to the sludge, and a dissolution tank as in the case of conventional electrolyte addition is unnecessary. Of course, neither heating equipment nor heating energy is required.
- the electroosmotic dehydration method according to the seventh aspect is an electroosmotic dehydration method in which a water to be treated is sandwiched between an anode and a cathode and is dehydrated by energizing both electrodes while being compressed.
- a dehydration aid is added to the water-containing material to be treated during the dehydration.
- the electroosmotic dehydration method of the eighth aspect is characterized in that, in the seventh aspect, the dehydration aid is an electrolyte-containing liquid.
- the electroosmotic dehydration method of the ninth aspect is characterized in that, in the eighth aspect, the electrolyte-containing liquid is a dehydrated filtrate of an electroosmotic dehydrator.
- the electroosmotic dehydration method of the tenth aspect is characterized in that, in the eighth aspect, the electrolyte-containing liquid is a dehydrated filtrate at the initial stage of the dehydration process.
- the electroosmotic dehydration apparatus includes an electrode disposed opposite to each other, an energizing means for energizing between the opposed electrodes, a filter medium disposed between the opposed electrodes, and between the filter mediums or between the filter medium and one of them.
- the electroosmotic dehydration apparatus of the twelfth aspect is characterized in that, in the eleventh aspect, the adding means is a collecting and adding means for collecting the dehydrated filtrate that is collected and added to the water to be treated.
- the thirteenth aspect of the electroosmotic dewatering apparatus is characterized in that, in the twelfth aspect, the dehydrated filtrate collecting and adding means is configured to collect and add only the dehydrated filtrate in the initial stage of the dehydrating step.
- An electroosmotic dehydration apparatus is the thirteenth aspect, wherein the filter medium is a filter cloth belt, and is disposed on the upper surface so as to carry the water-containing material to be treated and movable in the longitudinal direction of the belt.
- a cathode is disposed below the cloth belt, and an anode is disposed above the filter cloth belt.
- a plurality of the anodes are arranged in the longitudinal direction of the filter cloth belt, and the pressing means includes:
- the depressurized filtrate collecting and adding means collects the dehydrated filtrate that has passed through the filter cloth belt at the upstream portion in the moving direction of the filter cloth belt, and is a portion downstream of the upstream portion. It is comprised so that it may add to a to-be-processed hydrate.
- the dehydration efficiency in the latter half of the dehydration process is improved. As described above, in the first half of the dehydration process, a large amount of electrolyte is present in the water to be treated, so that the dehydration efficiency is high. In the seventh to fourteenth aspects, even in the latter half when the electrolyte decreases, the dehydration efficiency is increased by the addition of the dehydration aid, so that a dehydrate with a low water content can be obtained.
- the electroosmotic dehydration method of the fifteenth aspect is an electroosmotic dehydration method in which a water to be treated is sandwiched between an anode and a cathode and dehydrated by energizing both electrodes while being compressed, wherein the dehydrated filtrate is treated with water to be treated.
- the electroosmotic dehydration method to be added only the dehydrated filtrate at the initial stage of the dehydration process is added to the water to be treated.
- the electroosmotic dehydration method of the sixteenth aspect is characterized in that, in the fifteenth aspect, the dehydrated filtrate of the first 60% or less of the total treatment time of the electroosmotic dehydration process is added to the water to be treated. Is.
- the electroosmotic dehydration apparatus includes an electrode disposed opposite to each other, an energizing means for energizing between the opposed electrodes, a filter medium disposed between the opposed electrodes, and between the filter mediums or between the filter medium and one of them.
- an energizing means for energizing between the opposed electrodes
- a filter medium disposed between the opposed electrodes
- the filter medium or between the filter medium and one of them.
- the electroosmotic dehydration apparatus having a clamping means for clamping the treated water-containing material between the electrodes and a collection / addition means for recovering the dehydrated filtrate for collecting the dehydrated filtrate and adding it to the treated water-containing material.
- the filtrate collection and addition means is configured to collect and add only the dehydrated filtrate at the initial stage of the dehydration step.
- An electroosmotic dehydration apparatus is the seventeenth aspect, wherein the filter medium is a filter cloth belt, and is disposed on the upper surface so as to carry a water-containing material to be treated and movable in the longitudinal direction of the belt.
- a cathode is disposed below the cloth belt, and an anode is disposed above the filter cloth belt.
- a plurality of the anodes are arranged in the longitudinal direction of the filter cloth belt, and the pressing means includes: The anode is pushed down, and the means for collecting and adding the dehydrated filtrate is arranged to collect the dehydrated filtrate that has permeated the filter cloth belt on the upstream side in the moving direction of the filter cloth belt. It is.
- the filtrate having high electrical conductivity generated at the initial stage of the dehydration step is collected and added to the hydrated product, so that the electrical conductivity of the hydrated product is increased, the dehydration rate is improved, and the moisture content is increased. A low dehydrated product can be obtained.
- FIG. 2a is a schematic longitudinal sectional view of the electroosmotic dehydrator according to the embodiment during press dehydration
- FIGS. 2b and 2c are sectional views taken along lines IIB-IIB and IIC-IIC in FIG. 2a.
- FIG. 3a is a schematic longitudinal sectional view in the belt feeding process of the electroosmotic dehydrator according to the embodiment
- FIG. 3b is a sectional view taken along the line IIIB-IIIB of FIG. 3a.
- FIG. 5a is a schematic longitudinal sectional view of the electroosmotic dehydrator according to the embodiment
- FIG. 5b is a sectional view taken along line VB-VB of FIG. 5a.
- It is a schematic longitudinal cross-sectional view of the electroosmosis dehydration apparatus which concerns on embodiment.
- It is a schematic longitudinal cross-sectional view of the electroosmosis dehydration apparatus which concerns on another embodiment.
- the sludge dewatering methods of the first to sixth aspects are characterized in that concentrated salt discharged from a wastewater treatment facility is added in advance to sludge to be subjected to electroosmotic dewatering.
- the concentrated salt used in the present invention is not particularly limited as long as it is a concentrated salt discharged from a wastewater treatment facility.
- the following (1) to (5) can be used.
- Concentrated salt discharged from a reverse osmosis membrane separation device or evaporator for concentrating salts in the treated water of biological treatment facilities for collecting and reusing organic wastewater (2) For desalination of seawater Concentrated salt discharged from reverse osmosis membrane separator or evaporator for concentrating salts in treated water of water treatment facility (3) To concentrate salts in concentrated water of ultrapure water production facility for desalinating city water Salt discharged from the reverse osmosis membrane separator
- electrolyte concentration of such a concentrated salt there is no particular restriction on the electrolyte concentration of such a concentrated salt, but these concentrated salts are usually discharged as a slurry having an electrolyte concentration of about 0.1 to 24.5% by weight and an electric conductivity of about 0.1 to 120 mS / cm. Is done.
- such a slurry-like concentrated salt is added to sludge used for dehydration. If the amount of concentrated salt added to sludge is excessively small, the effect of improving the dehydration efficiency due to the addition of concentrated salt cannot be obtained sufficiently. . Therefore, although the amount of the concentrated salt added depends on the electrolyte concentration of the concentrated salt, it should be 1% by weight or more, particularly about 5 to 15% by weight with respect to the sludge. It is preferable to add about 0.15 wt% concentrated salt.
- sludge Prior to electroosmotic dehydration, sludge is dehydrated cake with a moisture content of about 70 to 90% by mechanical dehydration using a mechanical dehydrator such as a pressure dehydrator such as a belt press or filter press or a centrifugal dehydrator. It is preferable to add the concentrated salt to the dehydrated cake so that the amount added to the sludge before dehydration is in the above-described ratio, and to perform electroosmotic dehydration treatment. Thus, mechanical dehydration treatment and electroosmosis dehydration treatment are performed. Can be combined to make a more efficient dehydration process.
- a conventionally known inorganic flocculant or polymer flocculant may be added.
- the inorganic flocculant include ferric sulfate (including polyferric sulfate), sulfuric acid
- ferric sulfate including polyferric sulfate
- iron-based inorganic flocculants such as ferrous chloride, ferric chloride, ferrous chloride, and iron-silica inorganic polymer flocculants can be used.
- the amount of iron-based inorganic flocculant added to the sludge can be either too much or too little to obtain dehydrated sludge with a sufficiently low water content. It is preferably 5 to 20% by weight, particularly 7 to 15% by weight.
- a polymer flocculant may be added together with the iron-based inorganic flocculant.
- the polymer flocculant is not particularly limited, but an amphoteric polymer flocculant (amphoteric polymer) is used. Is preferred.
- amphoteric polymer flocculant a monomer having an amino group or an ammonium base, a copolymer of (meth) acrylamide and (meth) acrylic acid or a salt thereof is preferable, and as a monomer having an amino group or an ammonium base, for example, (Meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloyloxy-2-hydroxypropyltrimethylammonium chloride and other (meth) acryloyloxyalkyl quaternary ammonium salts, (meth) (Meth) acryloyloxyalkyl tertiary amine salts such as acryloyloxyethyldimethylamine sulfate or hydrochloride, (meth) acryloyloxypropyldimethylamine hydrochloride, (meth) acryloy
- These monomers can be used individually by 1 type, or can also be used in combination of 2 or more type.
- (meth) acryloyloxyalkyl quaternary ammonium salts are excellent in the dehydration effect and can be preferably used, and acryloyloxyethyltrimethylammonium chloride and methacryloyloxyethyltrimethylammonium chloride can be particularly preferably used. .
- (meth) acrylic acid or a salt thereof examples include (meth) acrylic acid, sodium (meth) acrylate, ammonium (meth) acrylate, calcium (meth) acrylate, and the like. Among these, acrylic acid and sodium acrylate can be particularly preferably used.
- the amphoteric polymer flocculant can be copolymerized with another comonomer.
- examples of other comonomers include vinyl pyrrolidone, maleic acid, and methyl acrylate.
- the copolymerization amount of these comonomers is usually preferably 20 mol% or less, and more preferably 10 mol% or less.
- amphoteric polymer flocculants may be used alone or in combination of two or more.
- the addition amount of such a polymer flocculant is preferably about 0.2 to 1% by weight with respect to SS of sludge to be dehydrated.
- a concentrated salt is added and electroosmosis dehydration is performed with an electroosmosis dehydrator.
- Some electroosmotic dehydration devices that are generally available on the market have a mechanical dehydration unit and an electroosmosis dehydration unit. Therefore, mechanical dehydration and electroosmosis dehydration treatment are performed using a normal electroosmosis dehydration device.
- the concentrated salt can be added between the mechanical dehydration unit and the electroosmosis dehydration unit.
- a dehydrated cake having a moisture content of 70% or less, such as a moisture content of about 50 to 70%, can be obtained.
- the sludge to be dewatered by the sludge dewatering method of the present invention is not particularly limited, and the present invention is not limited to sludge generated in the biological treatment process of various industrial wastewater, and other sludge such as pressurized floating sludge of automobile wastewater. It is applicable to.
- an alkaline dehydrated filtrate having a pH of about 12 (usually pH 10 to 13) is generated due to the sludge containing concentrated salt.
- This dehydrated filtrate is preferably put into a biological wastewater treatment tank for treatment, thereby reducing the amount of alkali hydroxide such as sodium hydroxide added as a pH adjuster to the biological treatment tank along with the treatment of the dehydrated filtrate. Can be preferred.
- the dehydrated filtrate is introduced into the biological treatment tank for treatment, it is advantageous to return it to the biological treatment tank of the wastewater treatment facility that is the source of concentrated salt.
- FIG. 1 is a system diagram showing the case where the dehydrated filtrate of the electroosmosis dehydrator is returned to the biological treatment tank of the wastewater treatment facility that is the source of concentrated salt, and the raw water is the biological treatment tank.
- the biologically treated water is treated at 61, the biologically treated water is treated at the concentration facility 62, and the treated water from which the salts have been concentrated and removed is discharged out of the system.
- a part of the concentrated salt is disposed of as industrial waste, and the remaining part is added to sludge or dewatered cake fed to the electroosmotic dewatering facility 63.
- the sludge or dehydrated cake to which the concentrated salt has been added is subjected to electroosmotic dehydration in the electroosmotic dehydration equipment 3, and the obtained dehydrated cake is discharged out of the system and disposed of.
- the dehydrated filtrate is returned to the biological treatment tank 61 for processing.
- Example 1 Polymer is added to excess sludge (MLSS 8,000 mg / L) of organic waste water and mechanically dehydrated to obtain a dehydrated cake with a moisture content of 82%.
- the electroosmotic dehydration treatment was performed by adding 10% by weight to the sludge.
- the processing conditions of the mechanical dehydration process and the electroosmotic dehydration process were as follows.
- ⁇ Concentrated salt> Concentrated salt slurry discharged from a reverse osmosis membrane separation facility that biologically treats organic wastewater by the activated sludge method, concentrates the biologically treated water with a membrane, and concentrates and separates the electrolyte. Electrolyte concentration: 1.3 to 1.5% by weight, electric conductivity: 15 to 17 mS / cm
- the water content of the obtained dehydrated cake was 65%.
- Example 1 In Example 1, instead of the concentrated salt, dehydration was performed in the same manner except that sodium sulfate was added as a 10 wt% aqueous solution so that the amount of sodium sulfate added to SS in the dehydrated cake was 1.4 wt%. When the treatment was performed, the water content of the obtained dehydrated cake was 67%.
- the concentrated salt discharged from the wastewater treatment facility that has been disposed of in the past can be effectively used to greatly improve the dewatering efficiency in the electroosmotic dewatering process.
- FIGS. 2a and 3a are longitudinal sectional views along the longitudinal direction (belt rotating direction) of the electroosmotic dehydrator according to the seventh to fourteenth embodiments
- FIGS. 2b and 2c are views of FIG. 2a.
- FIG. 3b is a sectional view taken along line IIIB-IIIB of 3a.
- 2a and 2b show the state of the dehydration process
- FIGS. 3a and 3b show the state of the belt feeding process of the electroosmotic dehydrator.
- the conveyor belt 1 made of filter cloth is stretched between the rollers 2 and 3 in an endless manner and can be rotated endlessly.
- the upper side of this conveyor belt 1 is the sludge transport side, and the lower side is the return side.
- a plate-like cathode 4 is disposed on the lower surface of the conveyor belt 1 on the conveyance side.
- the cathode 4 is a plate-like member made of a conductive material such as metal and has a large number of holes penetrating in the vertical direction.
- the cathode 4 extends from the immediate vicinity of the roller 2 to the immediate vicinity of the roller 3.
- a hopper 5 is provided so as to supply water to be treated (sludge S in this embodiment) to the upstream portion of the conveyor belt 1 in the transport direction.
- trays 6 and 7 for receiving the filtrate falling through the hole of the cathode 4 are provided.
- the tray 6 is arranged on the upstream side in the conveying direction of the conveyor belt 1, and the tray 7 is arranged on the downstream side in the conveying direction.
- the anode units 21 to 25 are arranged in the conveying direction of the conveyor belt 1, the tray 6 is disposed below the anode units 21 to 23 on the first half side, and the tray 7 is placed on the second half. It arrange
- the filtrate collected in the tray 6 is introduced into the filtrate storage tank 8 and can be supplied to a spray nozzle 12 described later via a pump and piping (not shown).
- the filtrate collected in the tray 7 is sent to the water treatment facility via the pipe 11.
- Anode units 21, 22, 23, 24, and 25 are installed above the conveyor unit of the conveyor belt 1. As shown in FIGS. 2b and 2c, side wall plates 20 made of an electrically insulating material are erected on both sides of the conveying portion of the conveyor belt 1 so that the sludge on the conveyor belt 1 does not protrude sideways. It is configured. The anode units 21 to 25 are disposed between the side wall plates 20 and 20.
- anode units are arranged in the conveyor belt conveying direction, but the present invention is not limited to this. Usually, about 2 to 5 anode units may be arranged in the conveying direction of the conveyor belt.
- Each anode unit 21 to 25 has an anode plate 33 fixed to the lower surface and an air cylinder (not shown).
- the upper end of the air cylinder is fixed to the main body of the electroosmosis dehydrator, and when air is supplied into the air cylinder, the anode plate 33 moves downward. When air is discharged from the air cylinder, the anode plate 33 is lifted and raised.
- the upper end of the air cylinder is attached to a beam (not shown) which is the main body of the electroosmotic dehydrator. This beam is fixedly installed above the conveyor belt 1.
- a DC current is applied to the anode plates 33 of the anode units 21 to 25 from a DC power supply (not shown).
- the spray nozzle 12 is disposed between the anode unit 23 and the anode unit 24, and the dehydrated filtrate in the tank 8 is sprayed and added to the sludge on the conveyor belt 1.
- two spray nozzles 12 are provided in the width direction of the conveyor belt 1, but one or three spray nozzles may be provided.
- the sludge S supplied into the hopper 5 is fed onto the conveyor belt 1 and a direct current is applied to each of the anode units 21 to 25. Then, air is supplied to the air cylinders of the anode units 21 to 25, and the sludge is pressed from above by the anode plates 33 of the anode units 21 to 25.
- the voltage is applied so that the anode units 21 to 25 are positive and the cathode plate 4 is negative. Although it is preferable to apply the same voltage to each of the anode units 21 to 25 from the viewpoint of facilitating operation management of the apparatus, the voltage is increased or decreased on the downstream side in the transport direction. May be. Further, energization control may be performed so that the current values of the anode units are the same.
- the air having the same pressure may be supplied to the air cylinders of the anode units 21 to 25, or the supply air pressure may be increased or decreased as the anode unit on the downstream side.
- the current is passed between the anode units 21 to 25 and the cathode plate 4 and the sludge is electroosmotic dehydrated by pressing the sludge with the anode plate 33 of the anode units 21 to 25.
- the dehydrated filtrate passes through the conveyor belt 1, passes through the holes of the cathode plate 4, and falls onto the trays 6 and 7.
- the filtrate that has fallen on the tray 6 has high electrical conductivity, and is stored in the storage tank 8 to be added on the conveyor belt 1 from the spray nozzle 12.
- each of the anode units 21 to 25 is energized, and when the sludge is pressed by the anode units 21 to 25, the conveyor belt 1 is stopped. After pressing and energizing for a predetermined time by the anode units 21 to 25, air is discharged from the air cylinders of the anode units 21 to 25, and the anode plate 33 is raised. Then, the conveyor belt 1 is moved by one pitch of the arrangement pitch of the anode units 21 to 25.
- the sludge located on the lower side of the anode unit 25 is sent out as dehydrated sludge, and the sludge located on the lower side of each of the anode units 21 to 24 is each one stage downstream of the anode units 22 to Move to the bottom of 25. Further, non-dehydrated sludge is introduced from the hopper 5 to the lower side of the anode unit 21.
- the dehydrated filtrate in the storage tank 8 is sprayed from the spray nozzle 12 and added to the sludge S on the conveyor belt 1.
- the electrical conductivity of the sludge to be treated in the latter half of the dehydration process is increased, and the anode units 24 and 25 and the cathode plate 4
- the electrical conductivity of the sludge between is increased and the dewaterability is improved. Thereby, the moisture content of the dewatered sludge obtained becomes low.
- the filtrate having a low electrical conductivity dropped on the tray 7 is not added to the sludge, an increase in the moisture content of the treated sludge is also suppressed, and this also reduces the moisture content of the obtained dewatered sludge. .
- the spray nozzle 12 is disposed between the anode units 23 and 24.
- the sludge is dehydrated to some extent and the water content is low. Therefore, even if the sludge is pressed by the anode unit after the dehydrated filtrate is sprayed from the spray nozzle 12, it is between the anode units 23 and 24. Sludge does not leak from the space.
- the electrical conductivity of the filtrate added to the sludge on the conveyor belt 1 from the spray nozzle 12 is preferably 500 mS / m or more, particularly 1000 mS / m or more, and usually 2500 mS / m or less, particularly 2000 mS / m. The following is preferable.
- the spray nozzle 12 is disposed between the third and fourth anode units 23 and 24, but is not limited thereto.
- the position of the spray nozzle 12 is 50% or more from the most upstream side, for example, 50 It is preferable to make it 80%, especially 50-70%.
- the amount of the filtrate added to the sludge on the conveyor belt 1 is preferably 5% by weight or more, particularly 10% by weight or more, based on the sludge weight existing on the conveyor belt 1 downstream of the spray nozzle 12. It is preferably 20% by weight or less, particularly preferably 15% by weight or less.
- the spray nozzle 12 is arranged between the anode units 23 and 24.
- the dehydrated filtrate may be sprayed and added to the sludge S on the conveyor belt 1.
- the gap between the anode units 23 and 24 can be reduced, and sludge can be prevented from leaking out between the anode units 23 and 24 during sludge pressing.
- spray nozzles may be arranged at a plurality of locations in the conveying direction of the conveyor belt 1 such as between the anode units 23 and 24 and between the anode units 24 and 25.
- the sludge is electroosmotically dehydrated by the anode units 21 to 25, the conveyor belt 1 and the cathode 4, but the present invention can also be applied to another type of electroosmotic dehydrator.
- the present invention can also be applied to an electroosmotic dehydrator that sandwiches sludge S between an anode drum and a conveyor belt that also serves as a cathode.
- the present invention can also be applied to an electroosmotic dehydration apparatus of a type in which a workpiece is sandwiched between filter media.
- Patent Document 4 Japanese Patent Publication No. 7-73646
- Patent Document 5 Patent No.
- Non-Patent Document 1 Water Treatment Management Handbook P.340, Tables 8 and 6
- the present invention can also be applied to a pressure-squeezing type electroosmotic dehydration apparatus that sandwiches sludge through a pressing membrane and an electrode.
- the present invention can also be applied to an electroosmotic dehydration method using a type of electroosmosis dehydrator other than the one shown in the figure.
- an electrolyte solution other than the dehydrated filtrate may be added to the water to be treated during dehydration.
- electrolyte solution examples include salt solutions such as sodium chloride, sodium sulfate, sodium carbonate, sodium hydrogen carbonate, and potassium chloride, and acid solutions such as hydrochloric acid, sulfuric acid, and nitric acid.
- the salt concentration of this solution is selected so that the electrical conductivity is in the preferred range.
- the salt may be dissolved in the dehydrated filtrate, and this may be added to the water to be treated during dehydration.
- sewage sludge with a moisture content of 78% was electroosmotic dehydrated.
- the operating conditions are as follows.
- Example 2 In the comparative example 2, the Na 2 SO 4 aqueous solution was added only when the conveyor belt 1 was moved from the spray nozzle 13 between the second and third anode units. The amount added was 2% by volume with respect to the sludge on the conveyor belt 1 on the downstream side of the position of the spray nozzle 13. As a result, the water content of the dewatered sludge was 61.3%, and the power consumption was 1379WH.
- Example 2 As in Example 2, the ultimate water content and power consumption can be reduced by adding a dehydrating aid during electroosmotic dehydration.
- Comparative Example 4 the power consumption is large. This is probably because an auxiliary agent was added at the initial stage of dehydration even though the cation was relatively contained in the sludge, so that the current flowed more than necessary. Further, in Comparative Example 4, although the ultimate moisture content is improved as compared with Comparative Example 3 due to the effect of the dehydrating aid, the moisture content is higher than that in Example 2. This is presumably because the amount of cation was insufficient in the latter half of the dehydration process because the dehydration aid was added to the inlet sludge.
- FIGS. 5a and 6 are longitudinal sectional views along the longitudinal direction (belt rotation direction) of the electroosmotic dehydration apparatus according to the embodiments of the 15th to 18th aspects
- FIG. 5b is a view of VB of FIG. 5a. It is sectional drawing which follows the -VB line. 5a and 5b show the state of the dehydration process
- FIG. 6 shows the state of the belt feeding process of the electroosmosis dehydrator.
- the conveyor belt 1 made of filter cloth is stretched between the rollers 2 and 3 in an endless manner and can be rotated endlessly.
- the upper side of this conveyor belt 1 is the sludge transport side, and the lower side is the return side.
- a plate-like cathode 4 is disposed on the lower surface of the conveyor belt 1 on the conveyance side.
- the cathode 4 is a plate-like member made of a conductive material such as metal and has a large number of holes penetrating in the vertical direction.
- the cathode 4 extends from the immediate vicinity of the roller 2 to the immediate vicinity of the roller 3.
- a hopper 5 is provided so as to supply water to be treated (sludge S in this embodiment) to the upstream portion of the conveyor belt 1 in the transport direction.
- trays 6 and 7 for receiving the filtrate falling through the hole of the cathode 4 are provided.
- the tray 6 is arranged on the upstream side in the conveying direction of the conveyor belt 1, and the tray 7 is arranged on the downstream side in the conveying direction.
- the anode units 21 to 25 are arranged in the conveying direction of the conveyor belt 1, the tray 6 is disposed below the anode units 21 to 23, and the tray 7 includes the anode units 24, 25 is arranged on the lower side.
- the filtrate collected in the tray 6 is introduced into the filtrate storage tank 8 and can be supplied to the hopper 5 through the pump 9 and the pipe 10.
- the filtrate collected in the tray 7 is sent to the water treatment facility via the pipe 11.
- Anode units 21, 22, 23, 24, and 25 are installed above the conveyor unit of the conveyor belt 1. As shown in FIG. 5b, side wall plates 20 are erected on both sides of the conveyor unit of the conveyor belt 1 so that the sludge on the conveyor belt 1 does not protrude sideways. The anode units 21 to 25 are disposed between the side wall plates 20 and 20.
- anode units are arranged in the conveyor belt conveying direction, but the present invention is not limited to this. Usually, about 2 to 5 anode units may be arranged in the conveying direction of the conveyor belt.
- Each anode unit 21 to 25 has an anode plate 33 fixed to the lower surface and an air cylinder (not shown).
- the upper end of the air cylinder is fixed to the main body of the electroosmosis dehydrator, and when air is supplied into the air cylinder, the anode plate 33 moves downward. When air is discharged from the air cylinder, the anode plate 33 is lifted and raised.
- the upper end of the air cylinder is attached to a beam (not shown) which is the main body of the electroosmotic dehydrator. This beam is fixedly installed above the conveyor belt 1.
- a DC current is applied to the anode plates 33 of the anode units 21 to 25 from a DC power supply (not shown).
- the sludge S supplied into the hopper 5 is fed onto the conveyor belt 1 and a direct current is applied to each of the anode units 21 to 25. Then, air is supplied to the air cylinders of the anode units 21 to 25, and the sludge is pressed from above by the anode plates 33 of the anode units 21 to 25.
- the voltage is applied so that the anode units 21 to 25 are positive and the cathode plate 4 is negative. Applying the same voltage to each of the anode units 21 to 25 is preferable from the viewpoint of facilitating operation management of the apparatus. May be. Further, energization control may be performed so that the current values of the anode units are the same.
- the air having the same pressure may be supplied to the air cylinders of the anode units 21 to 25, or the supply air pressure may be increased or decreased as the anode unit on the downstream side.
- the current is passed between the anode units 21 to 25 and the cathode plate 4 and the sludge is electroosmotic dehydrated by pressing the sludge with the anode plate 33 of the anode units 21 to 25.
- the dehydrated filtrate passes through the conveyor belt 1, passes through the holes of the cathode plate 4, and falls onto the trays 6 and 7. Since the filtrate dropped on the tray 6 has high electrical conductivity, the filtrate is stored in the storage tank 8 and added to the sludge in the hopper 5 through the pump 9 and the pipe 10.
- the electrical conductivity of the sludge to be treated is increased, and the electrical conductivity of the sludge between the anode units 21 to 25 and the cathode plate 4 is increased. Becomes higher and the dehydrating property is improved. Thereby, the moisture content of the dewatered sludge obtained becomes low.
- the filtrate having a low electrical conductivity dropped on the tray 7 is not added to the sludge, an increase in the moisture content of the treated sludge is also suppressed, and this also reduces the moisture content of the obtained dewatered sludge. .
- each of the anode units 21 to 25 is energized, and when the sludge is pressed by the anode units 21 to 25, the conveyor belt 1 is stopped. After pressing and energizing for a predetermined time by the anode units 21 to 25, air is discharged from the air cylinders of the anode units 21 to 25, and the anode plate 33 is raised. Then, the conveyor belt 1 is moved by one pitch of the arrangement pitch of the anode units 21 to 25.
- the sludge located on the lower side of the anode unit 25 is sent out as dehydrated sludge, and the sludge located on the lower side of each of the anode units 21 to 24 is each one stage downstream of the anode units 22 to Move to the bottom of 25.
- non-dehydrated sludge is introduced from the hopper 5 to the lower side of the anode unit 21.
- the anode plates 33 of the respective anode units 21 to 25 are pushed down and energized between the respective anode units 21 to 25 and the cathode 4 to perform electroosmotic dehydration treatment of sludge. Thereafter, the sludge is electroosmotic dehydrated by repeating this process.
- the electrical conductivity of the filtrate added from the pipe 10 to the sludge in the hopper 5 is preferably 500 mS / m or more, particularly 1000 mS / m or more, and usually 2500 mS / m or less, particularly 2000 mS / m or less. Preferably there is.
- the total dehydration time is 100%, it is usually preferable to add the dehydrated filtrate obtained in the first 60% or less, particularly 40% or less, to the treated sludge.
- the amount of the filtrate added to the sludge in the hopper 5 is preferably 5% by weight or more, particularly 10% by weight or more, preferably 20% by weight or less, and particularly preferably 15% by weight or less, based on the sludge weight.
- the dehydrated filtrate in the storage tank 8 is added to the sludge before the electroosmotic dehydration treatment in the hopper 5, but the sludge is stored in the sludge storage tank or sludge supply pipe on the upstream side of the hopper 5. You may add to.
- the sludge is electroosmotic dehydrated by the anode units 2 to 1 to 25, the conveyor belt 1 and the cathode 4, but the present invention can also be applied to other types of electroosmotic dehydration apparatuses. It is.
- the present invention can also be applied to an electroosmotic dehydrator 40 that sandwiches sludge S between an anode drum 41 and a conveyor belt 42 that also serves as a cathode.
- the filtrate at the initial stage of dehydration is collected by the tray 43 and added to the treated sludge S.
- the addition position of the dehydrated filtrate to the treated sludge is arbitrary.
- the filtrate in the latter half of the dehydration process is collected by the tray 44 and sent to the water treatment facility.
- the present invention can also be applied to an electroosmotic dehydration device of a type in which a workpiece is sandwiched between filter media.
- Patent Document 4 Japanese Patent Publication No. 7-73646
- Patent Document 5 Patent No. 3576269
- Non-Patent Document 1 Water Treatment Management Handbook P.340, Tables 8 and 6
- the present invention can also be applied to a pressure-squeezing type electroosmotic dehydration apparatus that sandwiches sludge through a pressing membrane and an electrode.
- the dehydrated filtrate that flows out at the beginning of the dehydration process is collected and added to the treated sludge (raw mud), and the raw mud to which this filtrate has been added. May be subjected to electroosmotic dehydration in the processing step of the next batch or subsequent batches.
- sewage sludge with a moisture content of 82% was electroosmotic dehydrated.
- the operating conditions are as follows.
- Example 3 In Comparative Example 5 above, the dehydrated filtrate on the lower side of the upstream three-stage anode units 21 to 23 was collected, and this dehydrated filtrate (electric conductivity 1070 mS / m) was added at 10% by weight with respect to the raw mud. As a result, the moisture content of the dewatered sludge was 65%.
- Comparative Example 6 In Comparative Example 5, the lower dehydrated filtrate (electric conductivity 258 mS / m) of the anode unit 25 on the most downstream side was recovered, and 10% by weight of this dehydrated filtrate was added to the raw mud. As a result, the moisture content of the dewatered sludge was 72%.
Abstract
Description
(a) 脱水ろ液を回収し、脱水前汚泥に添加することで、脱水後ケーキのpHおよび電気伝導率を調整する(特許文献1)。
(b) 食塩や硫酸ナトリウム、炭酸ナトリウムなどの電解質を汚泥に添加する(特許文献4)。
(c) 導電活性剤を汚泥に添加する(特許文献2。ただし、特許文献2には、導電活性剤とは具体的にはどのようなものであるか記載されていない。)。
即ち、汚泥粒子の表面は-10~-20mVに帯電しており、その周囲の水は電気二重層を形成しプラスに帯電している。従って、陽極と陰極に挟まれた汚泥に直流電源を印加すると、プラスに帯電した水が陰極側に引き寄せられる。この状態で圧力を加えると、水は陰極側から濾液として排出され、汚泥の含水率が低下する。
なお、この際、陰極では還元反応が起きるため、脱水濾液はアルカリ性になる。
また、この濃縮塩は、スラリー状であるため、汚泥に直接添加しても均一に分散させることができ、従来の電解質添加の場合のような溶解槽が不要である。もちろん、加温設備や加温エネルギーも不要である。
第1~第6態様の汚泥脱水方法は、電気浸透脱水処理に供される汚泥に、予め排水処理設備から排出される濃縮塩を添加することを特徴とする。
(2) 海水を淡水化処理する上水処理設備の処理水中の塩類を濃縮するための逆浸透膜分離装置又はエバポレーターから排出される濃縮塩
(3) 市水を脱塩処理する超純水製造設備の濃縮水中の塩類を濃縮するための逆浸透膜分離装置から排出される濃縮塩
一般的に市販されている電気浸透脱水装置は、機械的脱水部と電気浸透脱水部とを有する型式のものもあるため、通常の電気浸透脱水装置を用いて機械的脱水及び電気浸透脱水処理を行い、機械的脱水部と電気浸透脱水部との間で濃縮塩の添加を行うことができる。
加圧式脱水の場合の加圧力:50~1000kPa
遠心脱水の場合の遠心力:1000~2500G
脱水時間:1~60分
<電気浸透脱水処理条件>
加圧力:0.1~200kPa
通電量:DC20~100V
脱水時間:5~60分
有機系排水の余剰汚泥(MLSS8,000mg/L)にポリマーを添加して機械的脱水処理して、含水率82%の脱水ケーキを得、この脱水ケーキに、下記の濃縮塩を、脱水前の汚泥に対して10重量%添加して電気浸透脱水処理した。
このとき、機械的脱水処理及び電気浸透脱水処理の処理条件は以下の通りとした。
有機系排水を活性汚泥法により生物処理し、生物処理水を膜により濃縮して電解質を濃縮分離する逆浸透膜分離設備から排出される濃縮塩スラリー。電解質濃度:1.3~1.5重量%、電気伝導率:15~17mS/cm
回転数:2000/min
遠心効果:1000G
脱水時間:5m3/hr(SS8,000mg/Lの余剰汚泥を5m3/hrで脱水)
ポリマー添加量:1重量%対SS
<電気浸透脱水処理条件>
加圧力:0.16kgf/cm2(15.7kPa)
通電量:DC60V
脱水時間:10分
実施例1において、濃縮塩の代りに、硫酸ナトリウムを10重量%の水溶液として、脱水ケーキ中のSSに対する硫酸ナトリウム添加量が1.4重量%となるように添加したこと以外は同様にして脱水処理を行ったところ、得られた脱水ケーキの含水率は67%であった。
実施例1において、濃縮塩を添加しなかったこと以外は同様にして脱水処理を行ったところ、得られた脱水ケーキの含水率は73%であった。
第2a図及び第3a図は第7~14態様の実施の形態に係る電気浸透脱水装置の長手方向(ベルト回動方向)に沿う縦断面図であり、第2b,2c図は第2a図のIIB-IIB線、IIC-IIC線に沿う断面図、第3b図は第3aのIIIB-IIIB線に沿う断面図である。なお、第2a,2b図は脱水工程の様子を示しており、第3a,3b図は、この電気浸透脱水装置のベルト送り工程の様子を示している。
スプレーノズル13の位置:2番目と3番目の陽極ユニットの間
汚泥供給速度:12L/hr
陽極ユニットへの印加電圧:60V
脱水助剤を添加することなく、上記の条件で汚泥の電気浸透脱水処理を行った。脱水濾液についてはすべて水処理設備に送った。この結果、脱水汚泥の含水率は67.1%、消費電力は1429WHであった。
上記比較例1において、スプレーノズル13からNa2SO4水溶液(濃度120g/L)をホッパー5内の汚泥に対し2体積%の割合で添加した。この結果、脱水汚泥の含水率は62.4%、消費電力は1651WHであった。
上記比較例2において、Na2SO4水溶液を2番目と3番目の陽極ユニット同士の間のスプレーノズル13からコンベヤベルト1の送り移動時にのみ添加した。添加量は、スプレーノズル13の位置よりも下流側のコンベヤベルト1上の汚泥に対して2体積%とした。この結果、脱水汚泥の含水率は61.3%、消費電力は1379WHであった。
実施例2のように、電気浸透脱水途中で脱水助剤を添加することにより、到達含水率及び消費電力を低下させることができる。
第5a図及び第6図は第15~第18態様の実施の形態に係る電気浸透脱水装置の長手方向(ベルト回動方向)に沿う縦断面図であり、第5b図は第5a図のVB-VB線に沿う断面図である。なお、第5a,5b図は脱水工程の様子を示しており、第6図は、この電気浸透脱水装置のベルト送り工程の様子を示している。
汚泥供給速度:12L/hr
陽極ユニットへの印加電圧:60V
上記の条件で汚泥の電気浸透脱水処理を行った。脱水濾液についてはすべて水処理設備に送った。この結果、脱水汚泥の含水率は74%であった。
上記比較例5において、上流側3段の陽極ユニット21~23の下側の脱水濾液を回収し、この脱水濾液(電気伝導率1070mS/m)を原泥に対し10重量%添加した。その結果、脱水汚泥の含水率は65%となった。
上記比較例5において、最下流側の陽極ユニット25の下側の脱水濾液(電気伝導率258mS/m)を回収し、この脱水濾液を原泥に対し10重量%添加した。その結果、脱水汚泥の含水率は72%となった。
上記比較例5において、すべての陽極ユニット21~25の下側の脱水濾液を回収し、この脱水濾液(電気伝導率820mS/m)を原泥に対し10重量%添加した。その結果、脱水汚泥の含水率は68%となった。
なお、本出願は、2009年3月30日付で出願された日本特許出願(特願2009-082568)、2009年9月1日付で出願された日本特許出願(特願2009-201799)及び2010年3月15日付で出願された日本特許出願(特願2010-057589)に基づいており、その全体が引用により援用される。
Claims (18)
- 汚泥を電気浸透脱水装置で脱水処理する方法において、排水処理設備から排出される濃縮塩を該汚泥に添加した後、該電気浸透脱水装置で脱水処理することを特徴とする汚泥脱水方法。
- 請求項1において、前記汚泥に対する前記濃縮塩の添加量が1重量%以上であることを特徴とする汚泥脱水方法。
- 請求項1又は2において、前記汚泥を電気浸透脱水装置で脱水処理するに先立ち機械的脱水処理し、得られた脱水ケーキに前記濃縮塩を添加して電気浸透脱水装置で脱水処理することを特徴とする汚泥脱水方法。
- 請求項3において、前記脱水ケーキの含水率が70~90%であることを特徴とする汚泥脱水方法。
- 請求項1ないし4のいずれか1項において、前記濃縮塩が、排水の生物処理水を逆浸透膜分離処理又は蒸発濃縮により濃縮して得られる濃縮塩であることを特徴とする汚泥脱水方法。
- 請求項5において、前記電気浸透脱水装置による脱水処理で得られる脱水濾液を前記排水の生物処理槽に返送して処理することを特徴とする汚泥脱水方法。
- 陽極と陰極との間で被処理含水物を挟み、圧搾しながら両極間に通電して脱水する電気浸透脱水方法であって、
脱水助剤を被処理含水物に添加する電気浸透脱水方法において、
脱水助剤を脱水途中の被処理含水物に添加することを特徴とする電気浸透脱水方法。 - 請求項7において、脱水助剤は電解質含有液であることを特徴とする電気浸透脱水方法。
- 請求項8において、電解質含有液は電気浸透脱水装置の脱水濾液であることを特徴とする電気浸透脱水方法。
- 請求項8において、電解質含有液は、脱水工程初期の脱水濾液であることを特徴とする電気浸透脱水方法。
- 対向配置された電極と、
対向する電極間に通電する通電手段と、
対向する電極同士の間に配置された濾材と、
該濾材同士の間又は濾材と一方の電極との間で被処理含水物を挟圧するための挟圧手段と、
を有する電気浸透脱水装置において、
脱水助剤を脱水途中の被処理含水物に添加する手段を備えたことを特徴とする電気浸透脱水装置。 - 請求項11において、該添加手段は、脱水濾液を回収して被処理含水物に添加する脱水濾液の回収添加手段であることを特徴とする電気浸透脱水装置。
- 請求項12において、該脱水濾液の回収添加手段は、脱水工程の初期の脱水濾液のみを回収添加するよう構成されていることを特徴とする電気浸透脱水装置。
- 請求項13において、前記濾材は濾布ベルトであり、上面に被処理含水物を担持するように且つベルト長手方向に移動可能に配置されており、
該濾布ベルトの下側に陰極が配置され、該濾布ベルトの上方に陽極が配置されており、
該陽極は、該濾布ベルトの長手方向に複数個配列されており、
前記挟圧手段は、該陽極を押し下げるものであり、
前記脱水濾液の回収添加手段は、濾布ベルトの移動方向の上流側部分で濾布ベルトを透過した脱水濾液を回収し、該上流側部分よりも下流側の部分において被処理含水物に添加するよう構成されていることを特徴とする電気浸透脱水装置。 - 陽極と陰極との間で被処理含水物を挟み、圧搾しながら両極間に通電して脱水する電気浸透脱水方法であって、
脱水濾液を被処理含水物に添加する電気浸透脱水方法において、
脱水工程初期の脱水濾液のみを被処理含水物に添加することを特徴とする電気浸透脱水方法。 - 請求項15において、電気浸透脱水処理工程の全処理時間の、最初の60%以下の時間帯の脱水濾液を被処理含水物に添加することを特徴とする電気浸透脱水方法。
- 対向配置された電極と、
対向する電極間に通電する通電手段と、
対向する電極同士の間に配置された濾材と、
該濾材同士の間又は濾材と一方の電極との間で被処理含水物を挟圧するための挟圧手段と、
脱水濾液を回収して被処理含水物に添加する脱水濾液の回収添加手段と
を有する電気浸透脱水装置において、
該脱水濾液の回収添加手段は、脱水工程の初期の脱水濾液のみを回収添加するよう構成されていることを特徴とする電気浸透脱水装置。 - 請求項17において、前記濾材は濾布ベルトであり、上面に被処理含水物を担持するように且つベルト長手方向に移動可能に配置されており、
該濾布ベルトの下側に陰極が配置され、該濾布ベルトの上方に陽極が配置されており、
該陽極は、該濾布ベルトの長手方向に複数個配列されており、
前記挟圧手段は、該陽極を押し下げるものであり、
前記脱水濾液の回収添加手段は、濾布ベルトの移動方向の上流側で濾布ベルトを透過した脱水濾液を回収するように配置されていることを特徴とする電気浸透脱水装置。
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CN102730930A (zh) * | 2012-05-22 | 2012-10-17 | 江苏百新环境工程有限公司 | 电极式污泥压榨带 |
CN106904803A (zh) * | 2017-03-24 | 2017-06-30 | 河南工程学院 | 转换电极式电渗透高级氧化污泥脱水系统及其脱水方法 |
CN109485233A (zh) * | 2018-12-29 | 2019-03-19 | 启迪桑德环境资源股份有限公司 | 一种电渗透污泥高干脱水设备的倒极式滤室装置 |
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TWI409226B (zh) * | 2011-12-09 | 2013-09-21 | Ind Tech Res Inst | 一種處理高鹽度濃縮廢液之方法 |
CN102849916A (zh) * | 2012-10-09 | 2013-01-02 | 中国海诚工程科技股份有限公司 | 一种造纸污泥的脱水方法 |
CN103896473A (zh) * | 2014-03-28 | 2014-07-02 | 四川环能德美科技股份有限公司 | 电渗透污泥深度脱水设备 |
FR3042186B1 (fr) * | 2015-10-12 | 2021-12-10 | Veolia Water Solutions & Tech | Dispositif de deshydratation de boues |
CN108000923B (zh) * | 2017-10-26 | 2019-11-05 | 山东百川同创能源有限公司 | 一种垂直式电渗透螺旋挤压脱水一体化设备及其方法 |
CN109264947A (zh) * | 2018-12-06 | 2019-01-25 | 佛山科学技术学院 | 一种污泥处理方法 |
CN114804585A (zh) * | 2022-05-19 | 2022-07-29 | 浙大宁波理工学院 | 一种电渗焚烧联合处理污染底泥的方法 |
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CN109485233A (zh) * | 2018-12-29 | 2019-03-19 | 启迪桑德环境资源股份有限公司 | 一种电渗透污泥高干脱水设备的倒极式滤室装置 |
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