WO2016111324A1 - Organic sludge treatment method and treatment device - Google Patents

Organic sludge treatment method and treatment device Download PDF

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WO2016111324A1
WO2016111324A1 PCT/JP2016/050309 JP2016050309W WO2016111324A1 WO 2016111324 A1 WO2016111324 A1 WO 2016111324A1 JP 2016050309 W JP2016050309 W JP 2016050309W WO 2016111324 A1 WO2016111324 A1 WO 2016111324A1
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sludge
treatment
aeration
tank
concentration
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PCT/JP2016/050309
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French (fr)
Japanese (ja)
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直明 片岡
真司 植田
江理 大塚
良和 岩根
智之 森田
萩野　隆生
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水ｉｎｇ株式会社
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Priority to JP2016568742A priority Critical patent/JP6679503B2/en
Publication of WO2016111324A1 publication Critical patent/WO2016111324A1/en

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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
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/34—Biological treatment of water, waste water, or sewage characterised by the microorganisms used
    • 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
    • C02F11/02—Biological treatment
    • 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
    • C02F11/06—Treatment of sludge; Devices therefor by oxidation
    • 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 and apparatus for treating organic sludge, and particularly relates to a method and apparatus for treating hardly dewatered digested sludge.
  • methane fermentation technology for waste biomass such as food processing residue, food waste, sludge, etc., to increase the concentration of raw materials input to the facility for the purpose of downsizing the facility and improving the energy recovery rate of methane gas
  • the operation power is reduced to improve the efficiency of energy recovery (high concentration digestion method).
  • the TS concentration of methane fermentation sludge such as sewage sludge is 15 to 20 g / L
  • the TS concentration of methane fermentation sludge is 25 g / L or more.
  • sludge having a TS concentration of 25 g / L or more and an SS concentration (suspended solids) of 5 g / L or less than the TS concentration, the sludge becomes highly viscous or solid-liquid separable. Therefore, stable sludge treatment technology is required.
  • Patent Document 2 discloses that the digestion residue is sufficiently aerated to reduce the alkalinity and colloidal components of the digest residue due to the action of microorganisms, thereby improving the dehydration effect.
  • Patent Document 2 does not specify any aeration conditions, and the effect of the aeration process is not clear.
  • Patent Document 3 discloses that carbon dioxide dissolved in sludge by aeration is degassed to prevent aggregation inhibition due to foaming when a metal salt is added, thereby increasing cohesion.
  • Patent Document 3 Aeration conditions disclosed in Patent Document 3 5 ⁇ 10m 3 -Air / m 3 - Sludge ⁇ hr (0.083 ⁇ 0.167m 3 -Air / m 3 - sludge ⁇ min) 1 ⁇ at aeration amount of 3 hours.
  • Patent Document 3 only describes that there was almost no foaming at the time of addition of ferric chloride when performing aeration treatment (Example 1), and the degassing effect of the dissolved carbon dioxide gas was described. It has only been confirmed. Further, Patent Document 3 does not describe the TS concentration of anaerobic digested sludge, and cannot estimate it.
  • An object of the present invention is to provide a high concentration digested sludge treatment method and treatment apparatus that can achieve low cost and high dewatering efficiency.
  • the present inventors have obtained the knowledge that the high concentration digested sludge is hardly dehydrated by high concentration of the sticky component remaining in the high concentration digested sludge, and by reducing the viscosity of the high concentration digested sludge. They found that the amount of flocculant added could be reduced and the dehydration efficiency improved.
  • the processing method and processing apparatus of the following organic sludge are provided.
  • a method for treating organic sludge after anaerobic treatment wherein the organic sludge has a TS concentration of 25 g / L or more and an SS concentration of 5 g / L or less less than the TS concentration. It is a hardly dewatering digested sludge, and before dewatering the digested sludge, aeration treatment is performed by aeration of oxygen-containing gas to the hardly dewatering digested sludge to reduce the viscosity of the hardly dehydrated digested sludge.
  • a method for treating organic sludge is performed by aeration of oxygen-containing gas to the hardly dewatering digested sludge to reduce the viscosity of the hardly dehydrated digested sludge.
  • the aeration treatment is performed until the viscosity of the hardly dehydrated digested sludge after the aeration treatment is lowered to 200 mPa ⁇ s or less as measured at 30 ° C. with a B-type rotational viscometer defined in the sewage test method.
  • the aeration treatment is performed at an aeration intensity of 0.1 m 3 / (m 3 ⁇ min) or more and an aeration time of 4 hours or more and 48 hours or less, according to [1] or [2] Of organic sludge.
  • a flocculant is added to the digested sludge after the aeration treatment to form agglomerated sludge, the agglomerated sludge is dehydrated, and dehydrated separated water generated by the dehydration treatment is used as the diluent.
  • the method for treating organic sludge according to [8]. [10] The method for treating organic sludge according to [8], wherein polycoferric sulfate, ferric chloride, PAC (polyaluminum chloride) or a sulfuric acid band is used as the flocculant.
  • An anaerobic treatment tank for forming a hardly dehydrated digested sludge having a TS concentration of 25 g / L or more and an SS concentration of 5 g / L or less less than the TS concentration;
  • An aeration tank for aspirating oxygen-containing gas to the hardly dehydrated digested sludge;
  • a coagulation tank that forms coagulated sludge by adding a coagulant to the digested sludge after aeration treatment;
  • a control device that adjusts the aeration rate of the oxygen-containing gas supplied to the aeration tank according to the stirring resistance of the stirring device of the anaerobic treatment tank or the aggregation tank;
  • a dehydrator for dewatering the agglomerated sludge;
  • An organic sludge treatment apparatus comprising: [12] A nitrification / denitrification tank for nitrification / denitrification of the dewatered separated water from
  • An aerobic microorganism group-containing sludge supply pipe for adding the aerobic microorganism group-containing sludge from the nitrification / denitrification tank to the aeration tank or the hardly dehydrated digested sludge before flowing into the aeration tank.
  • the organic sludge treatment apparatus according to [12].
  • high-viscosity non-dehydrating property with a high concentration of TS concentration 25 to 50 g / L, SS concentration 18 to 45 g / L, preferably 20 to 40 g / L, such as methane fermentation sludge generated by anaerobic treatment Digested sludge can be efficiently dehydrated at low cost.
  • the organic sludge treatment method of the present invention by subjecting the hardly dewatered digested sludge to aeration treatment, the viscosity of the sludge decreases, the coagulation action and dewatering efficiency by the coagulant improve, and the chemical cost and dewatering cost. Can be greatly reduced.
  • the reduction in the sludge viscosity is considered to be due to the reduction in the adhesive component due to the aeration treatment.
  • the dewatered cake obtained by the treatment method of the present invention not only reduces the water content but also reduces the stickiness of the sludge, compared with the conventional dehydrated cake of high-concentration digested sludge. It is also possible to eliminate problems that have occurred in the post-treatment process such as a decrease in transfer efficiency due to sludge adhesion to the transport equipment and a decrease in drying efficiency due to sludge adhesion to the drying site in the sludge drying facility.
  • the organic sludge treatment method of the present invention is a method of treating organic sludge after anaerobic treatment, and the organic sludge has a TS concentration of 25 g / L or more and 5 g / L higher than the TS concentration. It is a hardly dewatering digested sludge having a low SS concentration, characterized in that before the digested sludge is dehydrated, it is aerated with an oxygen-containing gas to reduce the viscosity of the hardly dehydrated digested sludge. To do.
  • the object to be treated according to the present invention is a hardwater dehydrated having a TS concentration of 25 g / L or more, preferably 25 to 60 g / L, and an SS concentration of 5 g / L or less than the TS concentration. It is sex digested sludge. More preferably, it is a highly dewatering digested sludge having a high concentration and a high viscosity with a TS concentration of 25 to 50 g / L, more preferably 35 to 45 g / L, an SS concentration of 18 to 45 g / L, and more preferably 20 to 40 g / L. is there.
  • the sludge properties are as follows: pH 6.5-8.0, sludge viscosity 400-2000 mPa ⁇ s, preferably 400-1500 mPa ⁇ s at 30 ° C., measured with a B-type rotational viscometer specified in the sewage test method. In many cases, the content of coarse suspended solids is 3 to 20 wt%.
  • Non-dewaterable digested sludge is generated from the process of anaerobic treatment (methane fermentation treatment) of organic substances such as food production residues, garbage, and sludge.
  • a fully mixed methane fermenter or a dry methane fermenter that is operated in a medium temperature fermentation region and a high temperature fermentation region at a processing temperature of 30 to 60 ° C. under conditions of residence days (HRT) of 12 to 40 days. It is sludge.
  • Aeration treatment A difficult-to-dehydrate digested sludge is aerated with a gas containing oxygen, and the sticky component remaining in the sludge is decomposed by a chemical reaction together with a biological reaction to lower the sludge viscosity.
  • a large number of various aerobic microorganisms are alive, although the decomposition activity of the polymer component is not high. These aerobic microorganisms can ingest and decompose the sticky components remaining in the sludge in the anaerobic treatment process as a growth source. It is important to increase the degradation activity of molecular components.
  • the carbon dioxide gas dissolved in the sludge is decarboxylated, but also the residual organic matter and inorganic matter in the sludge are joined together by the cross-linking action and the organic matter is associated with each other.
  • the produced sticky matter and polymer-based sticky matter are reduced by biological reaction and chemical reaction by aeration treatment.
  • the sludge viscosity is reduced by reducing the molecular weight of the high-molecular substance remaining in the digested sludge having a molecular weight of 1 million to 2 million or more.
  • the temperature during the aeration treatment is preferably 10 to 50 ° C.
  • the pH is 7 to 9
  • the aeration intensity is 0.1 to 0.3 m 3 / (m 3 ⁇ min)
  • the aeration time is preferably 4 to 48 hours.
  • the oxygen-containing gas used for aeration is not a problem as long as it contains oxygen gas, and it has a low concentration that contains malodorous components generated from waste-receiving pits and waste sorting equipment in treatment facilities where non-dewaterable digested sludge is formed. And high-concentration odor gas, aerated exhaust gas generated from activated sludge treatment equipment for sewage, and the like can be used.
  • the dissolved oxygen (DO) concentration in the sludge during the aeration process is maintained at 1.0 mg / L or less.
  • the oxidation-reduction potential (ORP) of sludge is about -400 to +100 mV.
  • the aeration treatment is preferably carried out until the sludge has a viscosity of 200 mPa ⁇ s or less as measured at 30 ° C. using a B-type rotational viscometer defined in the sewage test method.
  • sludge containing aerobic microorganisms (hereinafter referred to as “aerobic microorganisms-containing sludge”) is added to the hardly dehydrated digested sludge before aeration treatment.
  • the adhesive component can be actively decomposed to reduce the sludge viscosity.
  • surplus concentrated sludge of activated sludge obtained from the nitrification denitrification step, or aerobic microorganism group-containing sludge such as composted sludge and biological deodorized sludge is preferable.
  • the amount of aerobic microorganism-containing sludge added depends on the sludge concentration, but is 5 to 20%, preferably about 5 to 10% of the amount of anaerobic digested sludge in consideration of sludge retention time in the aeration tank. preferable. If the added amount of sludge containing aerobic microorganisms greatly exceeds 20%, the sludge residence time in the aeration tank is shortened, so that the decomposition reaction of the sticky component is difficult to proceed, and in addition, the sparingly dehydrating surplus Sludge rate increases and dewatering performance decreases. Therefore, it is preferable that the added amount of the aerobic microorganism group-containing sludge is within a range in which the microorganism can contribute to the decomposition of the adhesive component.
  • the flocculant is not particularly limited, but a polymer flocculant is used.
  • an inorganic flocculating aid such as polyferric sulfate or sulfuric acid band, PAC and a polymer flocculating agent may be effective for increasing the clarity of the separated liquid.
  • the polymer flocculant include cationic, anionic, amphoteric, and the like, and examples thereof include amidine flocculants, acrylamide flocculants, and acrylic acid flocculants.
  • a comparatively inexpensive cationic polymer type flocculant for example, acrylic acid ester type, methacrylic acid ester type, and amphoteric type having higher cationic degree than anionic degree can be used.
  • the acrylic ester flocculant preferably has a molecular weight of about 3 to 6 million.
  • the addition rate of the polymer flocculant at the time of sludge aggregation is preferably 2 to 7 wt%, more preferably about 2 to 5 wt% with respect to the TS concentration of the sludge.
  • the aerated digested sludge Prior to the aggregating treatment, the aerated digested sludge may be diluted, and the aggregating agent injection rate can be reduced.
  • the diluted alkalinity of digested sludge is preferably 4000 mg / L or less, and more preferably 2500 mg / L or less.
  • the electric conductivity of the diluted digested sludge is preferably adjusted to 1200 mS / m or less, and more preferably adjusted to 750 mS / m or less.
  • process water in the treatment plant can be used.
  • biological treated water such as biological deodorization equipment waste liquid, dewatered separated water discharged from sludge dewatering treatment, boiler wastewater, on-site washing wastewater, composting condensed wastewater, miscellaneous wastewater, etc.
  • Aggregated flocs formed by the aggregation treatment may be subjected to solid-liquid separation before dehydration treatment to obtain a digested sludge concentrate, followed by dehydration treatment.
  • Concentrated floc is solid-liquid separated into sludge concentrate and separated liquid by the concentration treatment. Sludge concentrated to a TS concentration of 8 to 12 wt% can be dehydrated more efficiently.
  • the moisture content of the dehydrated cake obtained by the treatment method of the present invention is as low as 78-82%, it can be recycled such as composting, carbonization, and fueling. Since the separated water has an SS concentration of 100 to 2000 mg / L, M alkalinity of 1000 to 2000 mg / L, and electric conductivity of 200 to 500 mS / m, it can be used as a diluted solution of digested sludge.
  • the organic sludge treatment apparatus of the present invention comprises an anaerobic treatment tank for forming a hardly dewaterable digested sludge having a TS concentration of 25 g / L or more and an SS concentration of 5 g / L or less less than the TS concentration, An aeration tank for aeration of oxygen-containing gas to the hardly dehydrated digested sludge, an agglomeration tank for forming an agglomerated sludge by adding a flocculant to the digested sludge after aeration treatment, and stirring of the anaerobic treatment tank or the agglomeration tank It comprises a control device that adjusts the aeration rate of the oxygen-containing gas supplied to the aeration tank according to the stirring resistance of the device, and a dehydration device that dehydrates the agglomerated sludge.
  • a control device that adjusts the aeration rate of the oxygen-containing gas supplied to the aer
  • Anaerobic treatment tank such as a fully mixed methane fermentation tank or a dry methane fermentation tank generally used in waste-based biomass treatment equipment or sewage treatment facilities can be used without limitation.
  • an anaerobic treatment tank is equipped with a stirring means in order to prevent the occurrence of scum as well as the homogenization of the liquid in the tank and the uniform temperature distribution.
  • the mechanical stirring method is the most efficient, but a pump stirring method or a gas stirring method may be used according to the equipment environment and processing conditions.
  • a fermentation treatment tank having a watertight and airtight structure with these requirements it may be made of reinforced concrete or steel plate.
  • the anaerobic treatment tank may include a solubilization / acid fermentation treatment tank for solubilizing and subjecting the target biomass to acid fermentation, and an anaerobic treatment tank for fermenting the processed product in the tank.
  • An aeration tank generally used in water treatment facilities can be used without limitation, and means for introducing hardly dewatering digested sludge (such as methane fermentation sludge), to introduce oxygen-containing gas into digested sludge
  • an aeration means or aeration means such as a blower, and an aeration sludge extraction means, and a pH meter, a DO meter, an ORP meter, and a viscometer as measurement equipment for operation management.
  • the aeration means is preferably provided so that air bubbles can be introduced from the bottom of the aeration tank into the hardly dehydrated digested sludge in the aeration tank.
  • a sludge disperser such as a high-speed disperser may be provided in front of the aeration tank.
  • a slurry state in which hardly dewaterable digested sludge is uniformly dispersed can be maintained, and the aeration tank capacity can be reduced.
  • Control device A control device for adjusting the aeration rate of the oxygen-containing gas in accordance with the viscosity of the digested sludge is electrically connected to the anaerobic treatment tank or the coagulation tank and the aeration tank.
  • the viscosity of digested sludge cannot be measured automatically and continuously because a sample is collected and measured with a rotational viscometer.
  • the viscosity of the digested sludge in the anaerobic treatment tank or the coagulation tank is estimated based on the stirring resistance of the anaerobic treatment tank or the coagulation tank, and the viscosity of the digested sludge during the aeration process is estimated.
  • a stirrer in an anaerobic treatment tank or agglomeration tank is provided with a current detection unit, the stir resistance is obtained from the detected current value, and the viscosity fluctuation of the hardly dehydrated digested sludge in the aeration tank is estimated. To adjust to a predetermined aeration rate.
  • a coagulation tank generally used in water treatment facilities can be used without limitation.
  • the agglomeration tank has a post-aeration sludge supply pipe for supplying digested sludge after aeration treatment in the aeration tank, a flocculant supply pipe for adding a flocculant to the sludge, and an agglomeration floc formed by the agglomeration process.
  • the agglomerated sludge piping which sends the agglomerated sludge containing to a concentration tank is connected.
  • a solid-liquid separation device that solid-liquid separates the aggregation floc formed in the aggregation tank to form a concentration aggregation floc.
  • the solid-liquid separation device is not particularly limited, and is simply a tank to which the gravity concentration method is applied, a centrifugal separator to which the centrifugal concentration method is applied, a separator to which the floating concentration method is applied, a separator using a screen, etc. Is mentioned.
  • a slit type concentrator including a slit plate in which a large number of slits that allow liquid components to pass therethrough and a large number of discs having peripheral surfaces protruding on the slit plate is preferable.
  • the processed material received by the slit plate is sent to the discharge side on the slit plate by a large number of discs on the slit plate rotating eccentrically in the processed product discharge direction.
  • the liquid component falls from the gap with the disk and is filtered, and the solid component in the processed product is separated and collected.
  • a mechanical structure provided with a back pressure plate on the slit plate that rotates close to the upper surface of the slit plate in the discharge direction of the processed material and compresses and concentrates the collected material on the slit plate can be preferably used. .
  • a dewatering device for receiving and dewatering the coagulation floc from the coagulation tank or the concentration coagulation floc from the concentration tank is provided. It does not specifically limit as a dehydration apparatus, It is preferable to provide the filtration means which permeate
  • (G) Nitrification denitrification tank You may provide the nitrification denitrification tank which nitrifies and denitrifies the dehydration separation water from a dehydration apparatus.
  • Circulating nitrification / denitrification tanks, high-load denitrification tanks, and membrane separation-type high-load nitrification / denitrification tanks generally used in water treatment facilities and the like can be used without limitation.
  • two tanks may be provided: a denitrification tank in an anaerobic environment and a nitrification tank in an aerobic environment by aeration.
  • the circulation method by returning the nitrate produced by the aerobic microbial reaction in the nitrification tank to the denitrification tank and denitrifying by the anaerobic or facultative anaerobic microbial reaction.
  • the nitrification denitrogenation tank is divided into an anaerobic part and an aerobic part, adopts a biological suspension method, and performs solid-liquid separation of activated sludge and coagulated sludge with an ultrafiltration membrane. be able to.
  • (H) Diluent supply piping You may provide the diluent supply piping which adds the treated water from a nitrification denitrification tank to the digested sludge after an aeration process. It is preferable that the diluent supply pipe is connected to a pipe that connects the aeration tank and the aggregation tank. A pipe for feeding dehydrated separated water from the dehydration tank may be connected to the diluent supply pipe.
  • Aerobic microorganism group-containing sludge supply piping The aerobic microorganism group-containing sludge from the nitrification denitrification tank is extracted with a sludge extraction pump and added to the aeration tank or the hardly dehydrated digested sludge before flowing into the aeration tank.
  • An aerobic microorganism group-containing sludge supply pipe may be provided.
  • the aerobic microorganism group-containing sludge supply pipe is preferably connected to a pipe connecting the anaerobic treatment tank and the aeration tank.
  • Example 1 Using the methane fermented sludge (non-dewatered digested sludge) shown in Table 1, eight treatment tests shown in Table 2 were conducted to confirm the effect of improving the dehydration by aeration treatment.
  • 12 liters of methane fermentation sludge was put into a 20 liter tank, and continuous aeration was performed at a temperature of 30 ° C. and an aeration intensity of 0.25 m 3 / (m 3 ⁇ min).
  • the DO concentration in the sludge was 1.0 mg / L or less.
  • ⁇ TS Total solids, total evaporation residue
  • 105 ° C evaporation residue weight JIS K 0102
  • VS Volatile total solids, loss on ignition
  • 600 ° C loss on ignition JIS K 0102
  • SS Supended solids, suspended matter
  • 3,000rpm sediment weight in 10 minutes by centrifuge
  • VSS Volatile suspended solids
  • Loss on ignition of suspended materials at 600 °C JIS K 0102) ⁇ M alkalinity
  • Colloid charge amount Sludge surface charge amount, equivalent amount measured by colloid titration method (sewage test method)
  • Rough suspended matter content Analysis of loss on ignition of residue in sieve with nominal size of 74 ⁇ m
  • Example 2 Using the methane fermentation sludge shown in Table 1, aeration intensity of 0.1 m 3 / (m 3 ⁇ min), 0.2 m 3 / (m 3 ⁇ min), 0.3 m 3 / (m 3 ⁇ min) 3 Continuous aeration treatment was performed in series, and the change in sludge viscosity over time was examined.
  • the sludge temperature during the aeration treatment was 22 to 27 ° C., and the DO concentration was 1.0 mg / L or less.
  • the test results are shown in Table 4 and FIG. It was found that the sludge viscosity decreases in proportion to the aeration intensity and with the treatment time.
  • Example 2 From the test results of Example 1 and Example 2, it can be said that by subjecting the methane fermentation sludge to aeration treatment, the sludge viscosity is lowered and the dewaterability is improved.
  • the sludge viscosity (30 ° C.) is less than 200 mPa ⁇ s in just 4 hours and less than 100 mPa ⁇ s in 18 hours.
  • the aeration time is 4 to 80 hours, preferably 4 to 48 hours, more preferably about 18 to 48 hours, and particularly preferably 20 hours.
  • the aeration intensity is 0.2 m 3 / (m 3 ⁇ min)
  • the aeration time for achieving the sludge viscosity below 200 mPa ⁇ s is 15 to 80 hours. 18 hours to 50 hours is more preferable.
  • the aeration intensity is 0.1 m 3 / (m 3 ⁇ min)
  • the sludge viscosity becomes 100 mPa ⁇ s or less.
  • the aeration intensity is 0.2 m 3 / (m 3 ⁇ min) to 0.3 m 3 / (m 3 ⁇ min), the aeration time is 4 to 48 hours, preferably about 10 to 40 hours. It can be said that it is extremely effective in reducing the viscosity of hardly dewatered digested sludge.
  • Example 3 (A) TS concentration 30 g / L, SS concentration 18 g / L, (b) TS concentration 38 g / L, SS concentration 19 g / L, (c) TS concentration 44 g / L, SS concentration 30 g / L.
  • Digested (methane fermentation) sludge was subjected to continuous aeration treatment under the condition of aeration intensity of 0.24 m 3 / (m 3 ⁇ min), and the change with time in sludge viscosity (30 ° C.) was examined. The DO concentration was 1.0 mg / L or less.
  • the test results are shown in Table 5 and FIG.
  • the molecular weight distribution measurement by GPC was performed for each sample of aeration time 0 (h), 6 (h) and 12 (h) of sludge (a). After the sludge sample was diluted 10 times, the filtrate sample filtered through a 0.45 ⁇ m filter was introduced into a separation column (TSKgel GMPWXL manufactured by Tosoh Corporation), and GPC analysis was performed with an RI detector (differential refractive index detection). Pullulan (three types with average molecular weights of 23.5 million, 107,000, and 66,000) was used as a standard material for the polymer material. The analysis conditions are shown in Table 5 below.
  • FIG. 7 shows all the results side by side for the sake of convenience, and does not indicate that the measured value is high although the sample for aeration 12 hours (hr) is at the highest position.
  • the peak intensity was recognized based on the difference in RI intensity when the RI intensity (Retention Intensity) of 5 to 10 minutes was used as the baseline.
  • the polymer fraction peak at a retention time of about 13 to 14 minutes has a lower RI intensity as the aeration time becomes longer. Recognize.
  • a large peak is observed at a retention time of about 18 to 19 minutes.
  • the molecular weight is around 2.35 million (pullulan).
  • Table 6 shows the relationship between the aeration treatment time and the viscosity of the digested sludge
  • Table 7 shows the relationship between the aeration treatment time and the molecular weight.
  • Example 4 Based on the flow sheet of FIG. 2, various food manufacturing wastes were mixed and subjected to methane fermentation treatment under the conditions shown in Table 8. As aeration gas, high-concentration odor-containing air from processing equipment such as raw material receiving hopper, crusher, sorter, solubilization tank, composting fermenter, etc. is sucked in and introduced from the diffuser at the bottom of the aeration tank did.
  • processing equipment such as raw material receiving hopper, crusher, sorter, solubilization tank, composting fermenter, etc.
  • the aeration tank blower operation is based on the control device system diagram shown in FIG. 4 and is based on the initial setting when the sludge viscosity of the methane fermentation tank is 720 mPa ⁇ s and the sludge viscosity of the aeration tank is 105 mPa ⁇ s.
  • the initial current setting of 5% or more is detected, automatic control is performed to adjust the aeration rate by gradually increasing the blower intensity by 3%.
  • Table 9 shows the properties of methane fermentation sludge and sludge after aeration.
  • a flocculant was added to the digested sludge after the aeration treatment, followed by dehydration treatment.
  • a cationic polymer flocculant Watering Ebagulose CS-374D
  • an inorganic flocculant polyiron
  • Dehydration treatment (3) is the result of a dehydration test on a hardly dehydrated digested sludge that was not aerated in a comparative test.
  • Table 10 shows the flocculant addition rate, dehydrated cake properties after dehydration, and solids throughput per time in dehydration (1) to (3).
  • Example 5 Based on the flow sheet of FIG. 3, the same treatment as in Example 4 was performed, except that the activated sludge surplus concentrated sludge (aerobic microorganism group-containing sludge) obtained from the nitrification / denitrification step was introduced into the aeration tank. . The results are shown in Tables 11 and 12.
  • the viscosity of sludge is greatly reduced by subjecting the hardly-dehydrated digested sludge obtained by subjecting organic waste to high-concentration methane fermentation to aeration before dehydration. It is possible to improve coagulation performance and dewatering efficiency.
  • the amount of the flocculant added can be reduced (low chemical injection rate), and the high-concentration digested sludge can be dehydrated stably in a short time.
  • the dehydrated cake having a moisture content of 82% or less obtained by the present invention has a low moisture content, is not sticky, and has no special unpleasant odor compared to conventional dehydrated cakes. It is also suitable for recycling.

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Abstract

Provided is a treatment method and a treatment device for high density digestive sludge that are low cost and capable of achieving high dehydration efficacy. The method for treating organic sludge after anaerobic treatment is characterized in that the organic sludge is a digestive sludge that is highly difficult to dehydrate, has a TS density of at least 25 g/L and an SS density at least 5 g/L lower than the TS density and, before dehydration treating the digestive sludge, aeration treatment is performed with an oxygen-containing gas to lower the viscosity of the digestive sludge that is highly difficult to dehydrate.

Description

有機性汚泥の処理方法及び処理装置Organic sludge treatment method and treatment equipment
　本発明は、有機性汚泥の処理方法及び処理装置に関し、特に難脱水性消化汚泥の処理方法及び処理装置に関する。 The present invention relates to a method and apparatus for treating organic sludge, and particularly relates to a method and apparatus for treating hardly dewatered digested sludge.
　食品加工残渣、生ごみ、汚泥などの廃棄物系バイオマスを対象としたメタン発酵技術において、設備のコンパクト化やメタンガスのエネルギー回収率向上を目的として、設備への投入原料濃度を高濃度化することで運転動力を削減し、エネルギー回収の効率化を図ることが多い（高濃度消化法）。 In methane fermentation technology for waste biomass such as food processing residue, food waste, sludge, etc., to increase the concentration of raw materials input to the facility for the purpose of downsizing the facility and improving the energy recovery rate of methane gas In many cases, the operation power is reduced to improve the efficiency of energy recovery (high concentration digestion method).
　一方、メタン発酵時の汚泥濃度が高濃度化すると、発酵微生物の阻害反応に加えて、汚泥濃度の上昇に伴う移送、混合、撹拌時の設備容量や動力費増大、汚泥の難脱水化などの問題が発生してくる。特に、下水汚泥などの一般的なメタン発酵汚泥のＴＳ濃度（全蒸発残留物：Total solids）は１５～２０ｇ／Ｌであるのに対して、メタン発酵汚泥のＴＳ濃度が２５ｇ／Ｌ以上となる高濃度消化法では、発酵設備での適切な混合・撹拌技術とともに、難脱水化した発酵汚泥を簡便で安定的に汚泥処理できる技術が必要となっている。さらに、ＴＳ濃度が２５ｇ／Ｌ以上且つＳＳ濃度（懸濁物質：Suspended solids）がＴＳ濃度よりも５ｇ／Ｌ以上少ない性状の汚泥の場合には、汚泥が高粘質化したり、固液分離性が著しく低下したりする傾向が強く、安定した汚泥処理技術が要求されている。 On the other hand, when the sludge concentration at the time of methane fermentation is increased, in addition to the inhibition reaction of fermentation microorganisms, the equipment capacity and power cost at the time of transfer, mixing, stirring, increase in sludge concentration, sludge difficult dehydration, etc. Problems arise. In particular, the TS concentration of methane fermentation sludge such as sewage sludge is 15 to 20 g / L, whereas the TS concentration of methane fermentation sludge is 25 g / L or more. In the high-concentration digestion method, a technique capable of simply and stably treating sludge that has been hardly dehydrated together with appropriate mixing and stirring techniques in a fermentation facility is required. Furthermore, in the case of sludge having a TS concentration of 25 g / L or more and an SS concentration (suspended solids) of 5 g / L or less than the TS concentration, the sludge becomes highly viscous or solid-liquid separable. Therefore, stable sludge treatment technology is required.
　メタン発酵汚泥処理では、凝集薬剤を注入して汚泥中の懸濁物質を化学的に凝集処理した後、機械脱水することが多い。その際、ＴＳ濃度が２５ｇ／Ｌ以上の高濃度汚泥では、希釈液などで汚泥を希釈処理してから汚泥脱水処理する方法が採られている（特許文献１）。この高濃度消化汚泥の脱水処理に用いる高分子凝集剤としては、高価なアミジン系高分子凝集剤などが用いられ、適正な凝集フロックを形成させるためには薬注率５ｗｔ％以上（対ＴＳ濃度）の高い添加率で添加する必要があるため、薬品費が著しくコスト高となっていた。下水汚泥を対象とする一般的な嫌気性消化汚泥の脱水処理に用いられる高分子凝集剤が安価な非アミジン系高分子凝集剤で薬注率２ｗｔ％（対ＴＳ濃度）程度であることと比較すると、著しくコスト高であることが明らかであろう。 In methane fermentation sludge treatment, mechanical dehydration is often performed after injecting a coagulant and chemically coagulating suspended substances in the sludge. At that time, in the case of high-concentration sludge having a TS concentration of 25 g / L or more, a method of performing sludge dehydration treatment after diluting the sludge with a diluent or the like is employed (Patent Document 1). As the polymer flocculant used for dehydration treatment of this high-concentration digested sludge, an expensive amidine-based polymer flocculant or the like is used. In order to form an appropriate flocculent floc, a drug injection rate of 5 wt% or more (vs. TS concentration) ), The chemical cost is extremely high. Compared with the polymer flocculant used for dehydration treatment of general anaerobic digested sludge for sewage sludge is an inexpensive non-amidine polymer flocculant with a drug injection rate of about 2 wt% (vs. TS concentration). It will be clear that the cost is extremely high.
　嫌気性消化汚泥の脱水性を改善するために、嫌気性消化処理した消化残物（消化汚泥、又は消化液と消化汚泥との混合スラリー）を酸素含有ガスで曝気したのち機械脱水する方法が提案されている（特許文献２）。特許文献２には、消化残物を十分曝気処理することで、消化残物のアルカリ度およびコロイド成分が微生物の作用によって減少するために、脱水効果が向上することが開示されている。しかし、特許文献２には、曝気条件が何ら明記されておらず、曝気処理の効果が明確ではない。 In order to improve the dewaterability of anaerobic digested sludge, a method of mechanical dehydration after aerobically digested digested residue (digested sludge or a mixed slurry of digested liquid and digested sludge) with oxygen-containing gas is proposed. (Patent Document 2). Patent Document 2 discloses that the digestion residue is sufficiently aerated to reduce the alkalinity and colloidal components of the digest residue due to the action of microorganisms, thereby improving the dehydration effect. However, Patent Document 2 does not specify any aeration conditions, and the effect of the aeration process is not clear.
　また、嫌気性消化汚泥（ＳＳ濃度１．５３％＝１５．３ｇ／Ｌ）を曝気処理した後に余剰汚泥を混合し、得られた混合汚泥に金属塩を添加（第１段目の凝集反応）してから、凝集処理（第２段目の凝集反応）及び脱水処理を行う方法が提案されている（特許文献３）。特許文献３には、曝気により汚泥中に溶解している炭酸ガスを脱気し、金属塩を添加した際の発泡による凝集阻害を防止して凝集性を高めることが開示されている。また、余剰汚泥の混合によりアルカリ度を低下させ、金属塩（無機凝集剤）及び有機高分子凝集剤の凝集作用を改善すると記載されている。特許文献３に開示されている曝気条件は５～１０ｍ３－Ａｉｒ／ｍ３－汚泥・ｈｒ（０．０８３～０．１６７ｍ３－Ａｉｒ／ｍ３－汚泥・分）の曝気風量にて１～３時間である。特許文献３には、曝気処理を行った場合に塩化第二鉄の添加時に発泡が殆どなかった（実施例１）と記載されているに過ぎず、溶解している炭酸ガスの脱気効果が確認されているだけである。また、特許文献３には嫌気性消化汚泥のＴＳ濃度は記載されておらず、推定することもできない。 Moreover, anaerobic digested sludge (SS concentration 1.53% = 15.3 g / L) is aerated and then mixed with excess sludge, and a metal salt is added to the resulting mixed sludge (first-stage agglomeration reaction). Then, a method of performing an aggregating process (second-stage aggregating reaction) and a dehydrating process has been proposed (Patent Document 3). Patent Document 3 discloses that carbon dioxide dissolved in sludge by aeration is degassed to prevent aggregation inhibition due to foaming when a metal salt is added, thereby increasing cohesion. Further, it is described that the alkalinity is lowered by mixing excess sludge and the coagulation action of the metal salt (inorganic coagulant) and the organic polymer coagulant is improved. Aeration conditions disclosed in Patent Document 3 5 ~ 10m 3 -Air / m 3 - Sludge · hr (0.083 ~ 0.167m 3 -Air / m 3 - sludge · min) 1 ~ at aeration amount of 3 hours. Patent Document 3 only describes that there was almost no foaming at the time of addition of ferric chloride when performing aeration treatment (Example 1), and the degassing effect of the dissolved carbon dioxide gas was described. It has only been confirmed. Further, Patent Document 3 does not describe the TS concentration of anaerobic digested sludge, and cannot estimate it.
特開２０００－７９３９９号公報JP 2000-79399 A 特開昭６０－３８０９９号公報JP 60-38099 A 特開平８－２０６６９９号公報JP-A-8-206699
　本発明は、低コスト及び高脱水効率を達成できる高濃度消化汚泥の処理方法及び処理装置を提供することを目的とする。 An object of the present invention is to provide a high concentration digested sludge treatment method and treatment apparatus that can achieve low cost and high dewatering efficiency.
　本発明者らは、高濃度消化汚泥中に残留する粘着質成分が高濃縮されることによって高濃度消化汚泥が難脱水化するとの知見を得て、高濃度消化汚泥の粘度を低下させることによって、凝集剤の添加量を削減し、脱水効率を向上できることを見いだした。 The present inventors have obtained the knowledge that the high concentration digested sludge is hardly dehydrated by high concentration of the sticky component remaining in the high concentration digested sludge, and by reducing the viscosity of the high concentration digested sludge. They found that the amount of flocculant added could be reduced and the dehydration efficiency improved.
　本発明によれば、下記の有機性汚泥の処理方法及び処理装置が提供される。
［１］嫌気性処理後の有機性汚泥を処理する方法であって、当該有機性汚泥は、２５ｇ／Ｌ以上のＴＳ濃度と、当該ＴＳ濃度よりも５ｇ／Ｌ以上少ないＳＳ濃度と、を有する難脱水性消化汚泥であり、当該消化汚泥を脱水処理する前に、当該難脱水性消化汚泥に対して酸素含有気体を通気して曝気処理を行ない、当該難脱水性消化汚泥の粘度を低減させることを特徴とする有機性汚泥の処理方法。
［２］前記曝気処理は、曝気処理後の難脱水性消化汚泥の粘度が、下水試験方法に定められたＢ型回転粘度計による３０℃での測定で２００ｍＰａ・ｓ以下に低下するまで行うことを特徴とする［１］に記載の有機性汚泥の処理方法。
［３］前記曝気処理は、０．１ｍ３／（ｍ３・分）以上の曝気強度にて４時間以上４８時間以下の曝気時間で行うことを特徴とする［１］又は［２］に記載の有機性汚泥の処理方法。
［４］前記曝気強度は０．２ｍ３／（ｍ３・分）以上であることを特徴とする［３］に記載の有機性汚泥の処理方法。
［５］前記曝気処理に用いる酸素含有気体は、空気、又は処理対象となる有機性汚泥が形成される処理施設内で発生する臭気成分を含む空気であることを特徴とする［１］～［４］のいずれか１に記載の有機性汚泥の処理方法。
［６］前記曝気処理を行う前に、難脱水性消化汚泥に、好気性微生物群を含む汚泥を添加することを特徴とする［１］～［５］のいずれか１項に記載の有機性汚泥の処理方法。
［７］前記曝気処理は、前記難脱水性消化汚泥中の溶存酸素濃度を１．０ｍｇ／Ｌ以下に維持して行うことを特徴とする［１］～［６］のいずれか１に記載の有機性汚泥の処理方法。
［８］前記曝気処理後の消化汚泥に、６．０ｇ／Ｌ以下のＴＳ濃度を有する希釈液を添加して希釈した後、脱水処理することを特徴とする［１］～［７］のいずれか１項に記載の有機性汚泥の処理方法。
［９］前記曝気処理後の消化汚泥に凝集剤を添加して凝集汚泥を形成し、当該凝集汚泥を脱水処理し、脱水処理により発生する脱水分離水を前記希釈液として用いることを特徴とする［８］に記載の有機性汚泥の処理方法。
［１０］前記凝集剤としてポリ硫酸第二鉄、塩化第二鉄、ＰＡＣ（ポリ塩化アルミニウム）又は硫酸バンドを用いることを特徴とする［８］に記載の有機性汚泥の処理方法。
［１１］２５ｇ／Ｌ以上のＴＳ濃度と、当該ＴＳ濃度よりも５ｇ／Ｌ以上少ないＳＳ濃度と、を有する難脱水性消化汚泥を形成する嫌気性処理槽と、
当該難脱水性消化汚泥に酸素含有気体を曝気させる曝気槽と、
曝気処理後の消化汚泥に凝集剤を添加して凝集汚泥を形成する凝集槽と、
当該嫌気性処理槽又は当該凝集槽の撹拌装置の撹拌抵抗に応じて当該曝気槽に供給する酸素含有気体の曝気速度を調整する制御装置と、
当該凝集汚泥を脱水する脱水装置と、
を具備することを特徴とする、有機性汚泥の処理装置。
［１２］前記脱水装置からの脱水分離水を硝化脱窒素する硝化脱窒素槽と、
当該硝化脱窒素槽からの処理水を前記曝気処理後の消化汚泥に添加する希釈液供給配管をさらに具備することを特徴とする、［１１］に記載の有機性汚泥の処理装置。
［１３］前記硝化脱窒素槽からの好気性微生物群含有汚泥を前記曝気槽又は前記曝気槽に流入する前の難脱水性消化汚泥に添加する好気性微生物群含有汚泥供給配管をさらに具備することを特徴とする、［１２］に記載の有機性汚泥の処理装置。 According to this invention, the processing method and processing apparatus of the following organic sludge are provided.
[1] A method for treating organic sludge after anaerobic treatment, wherein the organic sludge has a TS concentration of 25 g / L or more and an SS concentration of 5 g / L or less less than the TS concentration. It is a hardly dewatering digested sludge, and before dewatering the digested sludge, aeration treatment is performed by aeration of oxygen-containing gas to the hardly dewatering digested sludge to reduce the viscosity of the hardly dehydrated digested sludge. A method for treating organic sludge.
[2] The aeration treatment is performed until the viscosity of the hardly dehydrated digested sludge after the aeration treatment is lowered to 200 mPa · s or less as measured at 30 ° C. with a B-type rotational viscometer defined in the sewage test method. [1] The organic sludge treatment method according to [1].
[3] The aeration treatment is performed at an aeration intensity of 0.1 m 3 / (m 3 · min) or more and an aeration time of 4 hours or more and 48 hours or less, according to [1] or [2] Of organic sludge.
[4] The organic sludge treatment method according to [3], wherein the aeration strength is 0.2 m 3 / (m 3 · min) or more.
[5] The oxygen-containing gas used for the aeration treatment is air or air containing an odor component generated in a treatment facility where organic sludge to be treated is formed [1] to [ [4] The method for treating organic sludge according to any one of [4].
[6] The organic material according to any one of [1] to [5], wherein a sludge containing an aerobic microorganism group is added to the hardly dehydrated digested sludge before the aeration treatment. Sludge treatment method.
[7] The method according to any one of [1] to [6], wherein the aeration treatment is performed while maintaining a dissolved oxygen concentration in the hardly dehydrated digested sludge at 1.0 mg / L or less. Organic sludge treatment method.
[8] Any one of [1] to [7], wherein the digested sludge after the aeration treatment is diluted by adding a diluent having a TS concentration of 6.0 g / L or less and then dehydrating. The processing method of the organic sludge of Claim 1.
[9] A flocculant is added to the digested sludge after the aeration treatment to form agglomerated sludge, the agglomerated sludge is dehydrated, and dehydrated separated water generated by the dehydration treatment is used as the diluent. The method for treating organic sludge according to [8].
[10] The method for treating organic sludge according to [8], wherein polycoferric sulfate, ferric chloride, PAC (polyaluminum chloride) or a sulfuric acid band is used as the flocculant.
[11] An anaerobic treatment tank for forming a hardly dehydrated digested sludge having a TS concentration of 25 g / L or more and an SS concentration of 5 g / L or less less than the TS concentration;
An aeration tank for aspirating oxygen-containing gas to the hardly dehydrated digested sludge;
A coagulation tank that forms coagulated sludge by adding a coagulant to the digested sludge after aeration treatment;
A control device that adjusts the aeration rate of the oxygen-containing gas supplied to the aeration tank according to the stirring resistance of the stirring device of the anaerobic treatment tank or the aggregation tank;
A dehydrator for dewatering the agglomerated sludge;
An organic sludge treatment apparatus, comprising:
[12] A nitrification / denitrification tank for nitrification / denitrification of the dewatered separated water from the dehydrator;
The apparatus for treating organic sludge according to [11], further comprising a diluent supply pipe for adding treated water from the nitrification denitrification tank to the digested sludge after the aeration treatment.
[13] An aerobic microorganism group-containing sludge supply pipe for adding the aerobic microorganism group-containing sludge from the nitrification / denitrification tank to the aeration tank or the hardly dehydrated digested sludge before flowing into the aeration tank. [10] The organic sludge treatment apparatus according to [12].
　本発明によれば、嫌気性処理により発生するメタン発酵汚泥などのＴＳ濃度２５～５０ｇ／Ｌ、ＳＳ濃度１８～４５ｇ／Ｌ、好ましくは２０～４０ｇ／Ｌの高濃度で高粘度の難脱水性消化汚泥を低コストで効率的に脱水処理することができる。 According to the present invention, high-viscosity non-dehydrating property with a high concentration of TS concentration 25 to 50 g / L, SS concentration 18 to 45 g / L, preferably 20 to 40 g / L, such as methane fermentation sludge generated by anaerobic treatment Digested sludge can be efficiently dehydrated at low cost.
　本発明の有機性汚泥の処理方法によれば、難脱水性消化汚泥を曝気処理することによって、当該汚泥の粘度が低下し、凝集剤による凝集作用と脱水効率が向上し、薬品コスト及び脱水コストを大幅に低減することができる。汚泥粘度の低減は、曝気処理による粘着質成分の低減によるものと考えられる。 According to the organic sludge treatment method of the present invention, by subjecting the hardly dewatered digested sludge to aeration treatment, the viscosity of the sludge decreases, the coagulation action and dewatering efficiency by the coagulant improve, and the chemical cost and dewatering cost. Can be greatly reduced. The reduction in the sludge viscosity is considered to be due to the reduction in the adhesive component due to the aeration treatment.
　従来は、高粘度の難脱水性消化汚泥を凝集及び脱水処理する際には、希釈により粘度を低下させることが必要であったが、本発明の方法によれば、凝集及び脱水処理の際の希釈が不要となるか、あるいは低希釈率で十分となる。よって、希釈液のコストを削減でき、脱水分離水の浄化のために行われる生物処理工程での分離膜濾過コスト及び下水道放流コストも削減することができる。 Conventionally, when coagulating and dehydrating high-viscosity hardly dewatering digested sludge, it was necessary to reduce the viscosity by dilution, but according to the method of the present invention, the coagulation and dehydrating treatment No dilution is necessary or a low dilution rate is sufficient. Therefore, the cost of the diluting liquid can be reduced, and the separation membrane filtration cost and sewer discharge cost in the biological treatment process performed for purification of the dehydrated separated water can also be reduced.
　また、従来の高濃度消化汚泥処理において、凝集剤としてポリ硫酸第二鉄などの鉄系無機凝集剤を用いる場合に問題となっていた脱炭酸反応に基づく発泡も著しく低減することができ、凝集槽における発泡制御も可能となる。 In addition, in conventional high-concentration digested sludge treatment, foaming based on a decarboxylation reaction, which has been a problem when using an iron-based inorganic flocculant such as polyferric sulfate as a flocculant, can be remarkably reduced. Foam control in the tank is also possible.
　さらに、本発明の処理方法によって得られる脱水ケーキは、従来の高濃度消化汚泥の脱水ケーキと比較して、含水率を低下させるだけではなく、汚泥の粘着性が低減されることから、脱水ケーキの搬送機器への汚泥付着に伴う移送効率低下、汚泥乾燥設備での乾燥部位への汚泥付着に伴う乾燥効率低下、などの後処理工程で生じていた不具合を解消することもできる。 Furthermore, the dewatered cake obtained by the treatment method of the present invention not only reduces the water content but also reduces the stickiness of the sludge, compared with the conventional dehydrated cake of high-concentration digested sludge. It is also possible to eliminate problems that have occurred in the post-treatment process such as a decrease in transfer efficiency due to sludge adhesion to the transport equipment and a decrease in drying efficiency due to sludge adhesion to the drying site in the sludge drying facility.
本発明の処理方法を示すフローチャートである。It is a flowchart which shows the processing method of this invention. 本発明の別の処理方法を示すフローチャートである。It is a flowchart which shows another processing method of this invention. 本発明の別の処理方法を示すフローチャートである。It is a flowchart which shows another processing method of this invention. 本発明の処理装置の構成を示す系統図である。It is a systematic diagram which shows the structure of the processing apparatus of this invention. 実施例２による曝気強度及び曝気時間と消化汚泥粘度との関係を示すグラフである。It is a graph which shows the relationship between the aeration intensity | strength and aeration time by Example 2, and digested sludge viscosity. 実施例３による高濃度汚泥に対する曝気時間と消化汚泥粘度との関係を示すグラフである。It is a graph which shows the relationship between the aeration time with respect to the high concentration sludge by Example 3, and digested sludge viscosity. 実施例３による曝気時間と分子量分布の変動を示すゲルパーミエーションクロマトグラフのチャートである。6 is a chart of a gel permeation chromatograph showing aeration time and variation in molecular weight distribution according to Example 3.
好ましい実施形態Preferred embodiment
　以下、添付図面を参照しながら本発明を詳細に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited thereto.
　本発明の有機性汚泥の処理方法は、嫌気性処理後の有機性汚泥を処理する方法であって、当該有機性汚泥は、２５ｇ／Ｌ以上のＴＳ濃度と、当該ＴＳ濃度よりも５ｇ／Ｌ以上少ないＳＳ濃度と、を有する難脱水性消化汚泥であり、当該消化汚泥を脱水処理する前に、酸素含有気体による曝気処理を行ない、当該難脱水性消化汚泥の粘度を低減させることを特徴とする。 The organic sludge treatment method of the present invention is a method of treating organic sludge after anaerobic treatment, and the organic sludge has a TS concentration of 25 g / L or more and 5 g / L higher than the TS concentration. It is a hardly dewatering digested sludge having a low SS concentration, characterized in that before the digested sludge is dehydrated, it is aerated with an oxygen-containing gas to reduce the viscosity of the hardly dehydrated digested sludge. To do.
　（１）難脱水性消化汚泥
　本発明による処理対象は、２５ｇ／Ｌ以上、好ましくは２５～６０ｇ／ＬのＴＳ濃度と、当該ＴＳ濃度よりも５ｇ／Ｌ以上少ないＳＳ濃度と、を有する難脱水性消化汚泥である。より好ましくは、ＴＳ濃度２５～５０ｇ／Ｌ、さらに好ましくは３５～４５ｇ／Ｌ、ＳＳ濃度１８～４５ｇ／Ｌ、さらに好ましくは２０～４０ｇ／Ｌの高濃度で高粘度の難脱水性消化汚泥である。汚泥性状としては、ｐＨ６．５～８．０、下水試験方法に定められたＢ型回転粘度計で測定した３０℃での汚泥粘度４００～２０００ｍＰａ・ｓ、好ましくは４００～１５００ｍＰａ・ｓ、ＳＳに対する粗浮遊物含有率３～２０ｗｔ％であることが多い。難脱水性消化汚泥は、食品製造残渣、生ごみ、汚泥などの有機性物質を嫌気性処理（メタン発酵処理）する工程から発生する。一般には処理温度３０～６０℃の中温発酵領域及び高温発酵領域にて、滞留日数（ＨＲＴ）１２～４０日の条件で運転される完全混合型メタン発酵槽や乾式メタン発酵槽などから排出される汚泥である。 (1) Hardly dewatered digested sludge The object to be treated according to the present invention is a hardwater dehydrated having a TS concentration of 25 g / L or more, preferably 25 to 60 g / L, and an SS concentration of 5 g / L or less than the TS concentration. It is sex digested sludge. More preferably, it is a highly dewatering digested sludge having a high concentration and a high viscosity with a TS concentration of 25 to 50 g / L, more preferably 35 to 45 g / L, an SS concentration of 18 to 45 g / L, and more preferably 20 to 40 g / L. is there. The sludge properties are as follows: pH 6.5-8.0, sludge viscosity 400-2000 mPa · s, preferably 400-1500 mPa · s at 30 ° C., measured with a B-type rotational viscometer specified in the sewage test method. In many cases, the content of coarse suspended solids is 3 to 20 wt%. Non-dewaterable digested sludge is generated from the process of anaerobic treatment (methane fermentation treatment) of organic substances such as food production residues, garbage, and sludge. Generally, it is discharged from a fully mixed methane fermenter or a dry methane fermenter that is operated in a medium temperature fermentation region and a high temperature fermentation region at a processing temperature of 30 to 60 ° C. under conditions of residence days (HRT) of 12 to 40 days. It is sludge.
　（２）曝気処理
　酸素を含む気体で難脱水性消化汚泥を曝気処理して、当該汚泥中に残留する粘着質成分を生物的反応とともに化学的反応で分解させて汚泥粘度を低下させる。硝化脱窒素処理後の余剰汚泥や生物脱臭処理後の汚泥などには、種々の好気性微生物群が高分子成分の分解活性は高くないが多数生存している。これらの好気性微生物群は、嫌気性処理工程において汚泥中に残留する粘着質成分を生育源として摂取し分解することが可能であるため、曝気処理によって部分的に好気性雰囲気とすることによって高分子成分の分解活性を高めることが重要である。曝気処理では、汚泥中に溶解している炭酸ガスの脱炭酸反応が進行するのみでなく、汚泥中の残留有機物と無機物とが架橋作用で結合して生じた粘着物、有機物同士が会合して生じた粘着物、高分子系粘着物が曝気処理による生物的反応及び化学的反応で低減される。特に、消化汚泥中に残留する分子量１００万～２００万以上の高分子物質が低分子化されることで汚泥粘度が低減する。曝気処理時の温度は１０～５０℃、ｐＨは７～９、曝気強度は０．１～０．３ｍ３／（ｍ３・分）、曝気時間は４～４８時間が好ましい。曝気強度や処理時間が過大となると、汚泥中の粘着質成分ばかりでなく、汚泥自体の分解が進行して汚泥性状が更に変化して、後段の凝集処理や脱水処理に悪影響を及ぼす。曝気強度が０．１ｍ３／（ｍ３・分）未満では、汚泥粘度が高いため汚泥全体に曝気することが困難である。 (2) Aeration treatment A difficult-to-dehydrate digested sludge is aerated with a gas containing oxygen, and the sticky component remaining in the sludge is decomposed by a chemical reaction together with a biological reaction to lower the sludge viscosity. In the surplus sludge after nitrification denitrification treatment and the sludge after biological deodorization treatment, a large number of various aerobic microorganisms are alive, although the decomposition activity of the polymer component is not high. These aerobic microorganisms can ingest and decompose the sticky components remaining in the sludge in the anaerobic treatment process as a growth source. It is important to increase the degradation activity of molecular components. In the aeration treatment, not only the carbon dioxide gas dissolved in the sludge is decarboxylated, but also the residual organic matter and inorganic matter in the sludge are joined together by the cross-linking action and the organic matter is associated with each other. The produced sticky matter and polymer-based sticky matter are reduced by biological reaction and chemical reaction by aeration treatment. In particular, the sludge viscosity is reduced by reducing the molecular weight of the high-molecular substance remaining in the digested sludge having a molecular weight of 1 million to 2 million or more. The temperature during the aeration treatment is preferably 10 to 50 ° C., the pH is 7 to 9, the aeration intensity is 0.1 to 0.3 m 3 / (m 3 · min), and the aeration time is preferably 4 to 48 hours. When the aeration strength and the treatment time are excessive, not only the sticky components in the sludge but also the sludge itself is decomposed to further change the sludge properties and adversely affect the subsequent agglomeration treatment and dehydration treatment. When the aeration intensity is less than 0.1 m 3 / (m 3 · min), it is difficult to aerate the entire sludge because the sludge viscosity is high.
　曝気に用いる酸素含有気体としては、酸素ガスを含む気体であれば問題なく、難脱水性消化汚泥が形成される処理施設内のごみ受入ピットやごみ選別設備などから発生する悪臭成分を含む低濃度系および高濃度系の臭気ガス、汚水の活性汚泥処理設備から発生する曝気排ガスなどを用いることができる。曝気処理時の汚泥中の溶存酸素（ＤＯ）濃度は１．０ｍｇ／Ｌ以下に維持する。汚泥の酸化還元電位（ＯＲＰ）は多くの場合－４００～＋１００ｍＶ程度である。本発明において、曝気処理は、汚泥ｐＨ７．５～９．５、下水試験方法に定められたＢ型回転粘度計による３０℃での測定で汚泥粘度２００ｍＰａ・ｓ以下となるまで行うことが好ましい。 The oxygen-containing gas used for aeration is not a problem as long as it contains oxygen gas, and it has a low concentration that contains malodorous components generated from waste-receiving pits and waste sorting equipment in treatment facilities where non-dewaterable digested sludge is formed. And high-concentration odor gas, aerated exhaust gas generated from activated sludge treatment equipment for sewage, and the like can be used. The dissolved oxygen (DO) concentration in the sludge during the aeration process is maintained at 1.0 mg / L or less. In many cases, the oxidation-reduction potential (ORP) of sludge is about -400 to +100 mV. In the present invention, the aeration treatment is preferably carried out until the sludge has a viscosity of 200 mPa · s or less as measured at 30 ° C. using a B-type rotational viscometer defined in the sewage test method.
　また、曝気処理による生物的反応を促進する上では、曝気処理を行う前に、難脱水性消化汚泥に、好気性微生物群を含む汚泥（以下「好気性微生物群含有汚泥」という）を添加することが好ましく、粘着質成分を積極的に分解させ汚泥粘度を低下させることが可能である。添加することができる汚泥としては、硝化脱窒素工程から得られる活性汚泥の余剰濃縮汚泥、あるいは堆肥化汚泥、生物脱臭の汚泥などの好気性微生物群含有汚泥が好ましい。好気性微生物群含有汚泥の添加量は、その汚泥濃度にもよるが、曝気槽での汚泥滞留時間等を考慮して嫌気性消化汚泥量の５～２０％、好ましくは５～１０％程度が好ましい。好気性微生物群含有汚泥の添加量が２０％を大きく上回ると、曝気槽での汚泥滞留時間が短くなるために、粘着質成分の分解反応が進行しにくくなり、併せて、難脱水性の余剰汚泥率が高くなり、脱水性能が低下する。したがって、好気性微生物群含有汚泥の添加量は、微生物が粘着質成分の分解に寄与できる範囲にすることが好ましい。 In order to promote biological reaction by aeration treatment, sludge containing aerobic microorganisms (hereinafter referred to as “aerobic microorganisms-containing sludge”) is added to the hardly dehydrated digested sludge before aeration treatment. Preferably, the adhesive component can be actively decomposed to reduce the sludge viscosity. As the sludge that can be added, surplus concentrated sludge of activated sludge obtained from the nitrification denitrification step, or aerobic microorganism group-containing sludge such as composted sludge and biological deodorized sludge is preferable. The amount of aerobic microorganism-containing sludge added depends on the sludge concentration, but is 5 to 20%, preferably about 5 to 10% of the amount of anaerobic digested sludge in consideration of sludge retention time in the aeration tank. preferable. If the added amount of sludge containing aerobic microorganisms greatly exceeds 20%, the sludge residence time in the aeration tank is shortened, so that the decomposition reaction of the sticky component is difficult to proceed, and in addition, the sparingly dehydrating surplus Sludge rate increases and dewatering performance decreases. Therefore, it is preferable that the added amount of the aerobic microorganism group-containing sludge is within a range in which the microorganism can contribute to the decomposition of the adhesive component.
　（３）凝集処理
　曝気処理した消化汚泥に凝集剤を添加して凝集フロックを形成させ、凝集フロックを脱水処理する。 (3) Aggregation treatment An aggregating agent is added to the aerated digested sludge to form an aggregated floc, and the aggregated floc is dehydrated.
　凝集剤としては、特に限定されないが、高分子凝集剤が用いられる。また、ポリ硫酸第二鉄または硫酸バンド、ＰＡＣ等の無機系凝集助剤と高分子凝集剤の併用も分離液の清澄度を高めるために有効な場合がある。高分子凝集剤としては、カチオン系、アニオン系、両性系、等が挙げられ、例えば、アミジン系凝集剤、アクリルアミド系凝集剤、アクリル酸系凝集剤等が挙げられる。また、比較的安価なカチオンポリマー系凝集剤、例えば、アクリル酸エステル系、メタアクリル酸エステル系、アニオン度よりもカチオン度が高い両性系等を用いることができる。アクリル酸エステル系凝集剤としては、分子量が３００万～６００万程度が好ましい。汚泥凝集時の高分子凝集剤の添加率は、汚泥のＴＳ濃度に対して２～７ｗｔ％が好ましく、２～５ｗｔ％程度が更に好ましい。本凝集処理によって、直径、すなわちフロック径が数ミリ程度であり、沈降分離性が高い凝集フロックを形成することができる。 The flocculant is not particularly limited, but a polymer flocculant is used. In addition, the combined use of an inorganic flocculating aid such as polyferric sulfate or sulfuric acid band, PAC and a polymer flocculating agent may be effective for increasing the clarity of the separated liquid. Examples of the polymer flocculant include cationic, anionic, amphoteric, and the like, and examples thereof include amidine flocculants, acrylamide flocculants, and acrylic acid flocculants. Moreover, a comparatively inexpensive cationic polymer type flocculant, for example, acrylic acid ester type, methacrylic acid ester type, and amphoteric type having higher cationic degree than anionic degree can be used. The acrylic ester flocculant preferably has a molecular weight of about 3 to 6 million. The addition rate of the polymer flocculant at the time of sludge aggregation is preferably 2 to 7 wt%, more preferably about 2 to 5 wt% with respect to the TS concentration of the sludge. By this agglomeration treatment, it is possible to form an agglomerated floc having a diameter, that is, a floc diameter of about several millimeters and having high sedimentation separation.
　凝集処理の前に、曝気処理した消化汚泥を希釈してもよく、凝集剤注入率を低減することができる。希釈された消化汚泥のＭアルカリ度は、４０００ｍｇ／Ｌ以下が好ましく、２５００ｍｇ／Ｌ以下が更に好ましい。希釈された消化汚泥の電気伝導度は１２００ｍＳ／ｍ以下に調整することが好ましく、７５０ｍＳ／ｍ以下に調整することが更に好ましい。希釈液としては、通常の飲用水等の他、凝集作用及び脱水作用に影響を与えない性状、たとえば溶解性成分濃度が低いプロセス水、あるいは脱水処理後にさらに生物処理を行う高次処理施設においては生物処理に影響しない性状、たとえばｐＨ５～９、ＮＨ４－Ｎ１０００ｍｇ／Ｌ以下、ヘキサン抽出物質５００ｍｇ／Ｌ以下であれば、処理プラント内のプロセス水を用いることができる。具体的には、活性汚泥処理水、生物脱臭装置廃液などの生物処理水、汚泥脱水処理により排出される脱水分離水、ボイラ排水、場内洗浄排水、コンポスト化凝縮排水、雑排水などを使用することができる。 Prior to the aggregating treatment, the aerated digested sludge may be diluted, and the aggregating agent injection rate can be reduced. The diluted alkalinity of digested sludge is preferably 4000 mg / L or less, and more preferably 2500 mg / L or less. The electric conductivity of the diluted digested sludge is preferably adjusted to 1200 mS / m or less, and more preferably adjusted to 750 mS / m or less. As a diluting solution, in addition to normal drinking water, properties that do not affect the coagulation and dehydration effects, such as process water with a low concentration of soluble components, or higher treatment facilities that perform further biological treatment after dehydration If the properties do not affect biological treatment, such as pH 5-9, NH 4 -N 1000 mg / L or less, and hexane extractant 500 mg / L or less, process water in the treatment plant can be used. Specifically, use activated sludge treated water, biological treated water such as biological deodorization equipment waste liquid, dewatered separated water discharged from sludge dewatering treatment, boiler wastewater, on-site washing wastewater, composting condensed wastewater, miscellaneous wastewater, etc. Can do.
　（４）濃縮処理
　凝集処理により形成された凝集フロックを脱水処理前に固液分離して消化汚泥濃縮物としてから脱水処理してもよい。 (4) Concentration treatment Aggregated flocs formed by the aggregation treatment may be subjected to solid-liquid separation before dehydration treatment to obtain a digested sludge concentrate, followed by dehydration treatment.
　濃縮処理により、凝集フロックは汚泥濃縮物と分離液とに固液分離される。ＴＳ濃度８～１２ｗｔ％に濃縮された汚泥は、より効率的に脱水処理することができる。 凝集 Concentrated floc is solid-liquid separated into sludge concentrate and separated liquid by the concentration treatment. Sludge concentrated to a TS concentration of 8 to 12 wt% can be dehydrated more efficiently.
　（５）脱水処理
　凝集処理、又は凝集処理及び濃縮処理された消化汚泥の凝集フロックを脱水ケーキと分離水とに固液分離する。 (5) Dehydration treatment Aggregated flocs of digested sludge subjected to agglomeration treatment or agglomeration treatment and concentration treatment are subjected to solid-liquid separation into a dehydrated cake and separated water.
　本発明の処理方法により得られる脱水ケーキの含水率は７８～８２％以下と低含水率であるため、コンポスト化、炭化、燃料化などの再資源化が可能である。分離水は、ＳＳ濃度１００～２０００ｍｇ／Ｌ、Ｍアルカリ度１０００～２０００ｍｇ／Ｌ、電気伝導度２００～５００ｍＳ／ｍとなるため、消化汚泥の希釈液として用いることができる。 Since the moisture content of the dehydrated cake obtained by the treatment method of the present invention is as low as 78-82%, it can be recycled such as composting, carbonization, and fueling. Since the separated water has an SS concentration of 100 to 2000 mg / L, M alkalinity of 1000 to 2000 mg / L, and electric conductivity of 200 to 500 mS / m, it can be used as a diluted solution of digested sludge.
　本発明の有機性汚泥の処理装置は、２５ｇ／Ｌ以上のＴＳ濃度と、当該ＴＳ濃度よりも５ｇ／Ｌ以上少ないＳＳ濃度と、を有する難脱水性消化汚泥を形成する嫌気性処理槽と、当該難脱水性消化汚泥に酸素含有気体を曝気させる曝気槽と、曝気処理後の消化汚泥に凝集剤を添加して凝集汚泥を形成する凝集槽と、当該嫌気性処理槽又は当該凝集槽の撹拌装置の撹拌抵抗に応じて当該曝気槽に供給する酸素含有気体の曝気速度を調整する制御装置と、当該凝集汚泥を脱水する脱水装置と、を具備することを特徴とする。図４を参照しながら、各構成要素について説明する。 The organic sludge treatment apparatus of the present invention comprises an anaerobic treatment tank for forming a hardly dewaterable digested sludge having a TS concentration of 25 g / L or more and an SS concentration of 5 g / L or less less than the TS concentration, An aeration tank for aeration of oxygen-containing gas to the hardly dehydrated digested sludge, an agglomeration tank for forming an agglomerated sludge by adding a flocculant to the digested sludge after aeration treatment, and stirring of the anaerobic treatment tank or the agglomeration tank It comprises a control device that adjusts the aeration rate of the oxygen-containing gas supplied to the aeration tank according to the stirring resistance of the device, and a dehydration device that dehydrates the agglomerated sludge. Each component will be described with reference to FIG.
　（Ａ）嫌気性処理槽
　廃棄物系バイオマス処理設備や下水処理施設などで一般に用いられる完全混合型メタン発酵槽や乾式メタン発酵槽など、公知の嫌気性処理槽を制限なく用いることができる。 (A) Anaerobic treatment tank A well-known anaerobic treatment tank such as a fully mixed methane fermentation tank or a dry methane fermentation tank generally used in waste-based biomass treatment equipment or sewage treatment facilities can be used without limitation.
　通常、嫌気性処理槽は、槽内液の均質化や温度分布の均一化とともに、スカムの発生を防止するために撹拌手段を具備している。本発明では機械撹拌方式が最も効率的であるが、設備環境や処理条件に応じてポンプ撹拌方式やガス撹拌方式を使用してもよい。さらに、これらの要件を備えた水密かつ気密な構造の発酵処理槽であれば鉄筋コンクリート製または鋼板製のいずれでもよい。また、嫌気性処理槽は、対象バイオマスを可溶化および酸発酵処理する可溶化・酸発酵処理槽と、該槽での処理物を発酵処理する嫌気性処理槽と、を含む構成としてもよい。 Usually, an anaerobic treatment tank is equipped with a stirring means in order to prevent the occurrence of scum as well as the homogenization of the liquid in the tank and the uniform temperature distribution. In the present invention, the mechanical stirring method is the most efficient, but a pump stirring method or a gas stirring method may be used according to the equipment environment and processing conditions. Furthermore, as long as it is a fermentation treatment tank having a watertight and airtight structure with these requirements, it may be made of reinforced concrete or steel plate. The anaerobic treatment tank may include a solubilization / acid fermentation treatment tank for solubilizing and subjecting the target biomass to acid fermentation, and an anaerobic treatment tank for fermenting the processed product in the tank.
　（Ｂ）曝気槽
　水処理施設などで一般に用いられる曝気槽を制限なく用いることができ、難脱水性消化汚泥（メタン発酵汚泥など）を導入する手段、酸素含有気体を消化汚泥中に導入するためのブロワなどの曝気手段又は散気手段、曝気汚泥の引き抜き手段を備え、運転管理する計測機器としてｐＨ計、ＤＯ計、ＯＲＰ計、粘度計を備えることが好ましい。曝気手段は、曝気槽底部から曝気槽内の難脱水性消化汚泥中に気泡を導入できるように設けることが好ましい。 (B) Aeration tank An aeration tank generally used in water treatment facilities can be used without limitation, and means for introducing hardly dewatering digested sludge (such as methane fermentation sludge), to introduce oxygen-containing gas into digested sludge It is preferable to provide an aeration means or aeration means such as a blower, and an aeration sludge extraction means, and a pH meter, a DO meter, an ORP meter, and a viscometer as measurement equipment for operation management. The aeration means is preferably provided so that air bubbles can be introduced from the bottom of the aeration tank into the hardly dehydrated digested sludge in the aeration tank.
　さらに、曝気槽の前段に、高速分散機などの汚泥分散装置を設けてもよい。この場合には、難脱水性消化汚泥を均質に分散したスラリー状態を保持することができ、曝気槽容量を小型化することができる。 Furthermore, a sludge disperser such as a high-speed disperser may be provided in front of the aeration tank. In this case, a slurry state in which hardly dewaterable digested sludge is uniformly dispersed can be maintained, and the aeration tank capacity can be reduced.
　（Ｃ）制御装置
　嫌気性処理槽または凝集槽及び曝気槽には、消化汚泥の粘度に応じて酸素含有気体の曝気速度を調整する制御装置が電気的に連結されている。通常、消化汚泥の粘度の計測は、試料を採取して回転粘度計で計測するため、自動連続計測を行うことができない。本発明では、嫌気性処理槽または凝集槽の撹拌装置の撹拌抵抗に基づいて、嫌気性処理槽または凝集槽内の消化汚泥の粘度を推測し、曝気処理中の消化汚泥の粘度を推測して、曝気速度を調整する。具体的には、たとえば、嫌気性処理槽または凝集槽の撹拌装置に電流検出部を設け、検出された電流値から撹拌抵抗を求め、曝気槽内の難脱水性消化汚泥の粘度変動を推定して、所定の曝気速度に調整する。 (C) Control device A control device for adjusting the aeration rate of the oxygen-containing gas in accordance with the viscosity of the digested sludge is electrically connected to the anaerobic treatment tank or the coagulation tank and the aeration tank. Usually, the viscosity of digested sludge cannot be measured automatically and continuously because a sample is collected and measured with a rotational viscometer. In the present invention, the viscosity of the digested sludge in the anaerobic treatment tank or the coagulation tank is estimated based on the stirring resistance of the anaerobic treatment tank or the coagulation tank, and the viscosity of the digested sludge during the aeration process is estimated. Adjust the aeration rate. Specifically, for example, a stirrer in an anaerobic treatment tank or agglomeration tank is provided with a current detection unit, the stir resistance is obtained from the detected current value, and the viscosity fluctuation of the hardly dehydrated digested sludge in the aeration tank is estimated. To adjust to a predetermined aeration rate.
　（Ｄ）凝集槽
　水処理施設などで一般に用いられる凝集槽を制限なく用いることができる。凝集槽には、曝気槽にて曝気処理した後の消化汚泥を供給する曝気処理後汚泥供給配管、当該汚泥に対して凝集剤を添加する凝集剤供給配管、凝集処理により形成される凝集フロックを含む凝集汚泥を濃縮槽に送る凝集汚泥配管が連結されている。 (D) Coagulation tank A coagulation tank generally used in water treatment facilities can be used without limitation. The agglomeration tank has a post-aeration sludge supply pipe for supplying digested sludge after aeration treatment in the aeration tank, a flocculant supply pipe for adding a flocculant to the sludge, and an agglomeration floc formed by the agglomeration process. The agglomerated sludge piping which sends the agglomerated sludge containing to a concentration tank is connected.
　（Ｅ）濃縮槽
　凝集槽にて形成された凝集フロックを固液分離して濃縮凝集フロックを形成する固液分離装置を備える。固液分離装置としては、特に限定されず、重力濃縮法が適用される単なる槽、遠心濃縮法が適用される遠心分離機、浮上濃縮法が適用される分離機、スクリーンを用いた分離機等が挙げられる。中でも、液体成分を通過させる多数のスリットを形成したスリット板と、スリット板上に周面を突出せしめた多数の円板と、を備えるスリット型濃縮機が好ましい。スリット型濃縮機は、例えば、スリット板で受け止められた処理物は、処理物排出方向に偏心回転するスリット板上の多数の円板によってスリット板上を排出側に送られ、この過程でスリットと円板との隙間から液体成分が落下して濾過され、処理物中の固体成分は分離捕集される。さらに、スリット板の上面に近接して処理物の排出方向に回転し、スリット板上の捕集物を圧搾して濃縮する背圧板を上記スリット板上に設けた機械構造も好ましく用いることができる。 (E) Concentration tank A solid-liquid separation device is provided that solid-liquid separates the aggregation floc formed in the aggregation tank to form a concentration aggregation floc. The solid-liquid separation device is not particularly limited, and is simply a tank to which the gravity concentration method is applied, a centrifugal separator to which the centrifugal concentration method is applied, a separator to which the floating concentration method is applied, a separator using a screen, etc. Is mentioned. Among them, a slit type concentrator including a slit plate in which a large number of slits that allow liquid components to pass therethrough and a large number of discs having peripheral surfaces protruding on the slit plate is preferable. In the slit type concentrator, for example, the processed material received by the slit plate is sent to the discharge side on the slit plate by a large number of discs on the slit plate rotating eccentrically in the processed product discharge direction. The liquid component falls from the gap with the disk and is filtered, and the solid component in the processed product is separated and collected. Furthermore, a mechanical structure provided with a back pressure plate on the slit plate that rotates close to the upper surface of the slit plate in the discharge direction of the processed material and compresses and concentrates the collected material on the slit plate can be preferably used. .
　（Ｆ）脱水装置
　凝集槽からの凝集フロック、又は濃縮槽からの濃縮凝集フロックを受け入れ、脱水する脱水装置を備える。脱水装置としては特に限定されず、凝集フロック又は濃縮凝集フロックへ応力を付与する手段と、分離液を透過し、消化汚泥凝集物を保持するろ過手段を具備することが好ましい。応力を付与する手段としては、プレス、遠心等が挙げられる。ろ過手段としては、開孔径が０．１～２．５ｍｍのスクリ－ン等が挙げられる。 (F) Dewatering device A dewatering device for receiving and dewatering the coagulation floc from the coagulation tank or the concentration coagulation floc from the concentration tank is provided. It does not specifically limit as a dehydration apparatus, It is preferable to provide the filtration means which permeate | transmits a separated liquid and hold | maintains digested sludge aggregate, and a means to give stress to the aggregation floc or the concentration aggregation floc. Examples of means for applying stress include pressing and centrifugation. Examples of the filtering means include a screen having an opening diameter of 0.1 to 2.5 mm.
　（Ｇ）硝化脱窒素槽
　脱水装置からの脱水分離水を硝化脱窒素する硝化脱窒素槽を備えていてもよい。水処理施設などで一般に用いられる循環式硝化脱窒素槽、高負荷脱窒素槽、膜分離式高負荷硝化脱窒素槽を制限なく用いることができる。循環式硝化脱窒素槽の場合、嫌気的環境の脱窒槽、及び曝気等による好気的環境の硝酸化槽の２槽を設けてもよい。たとえば、硝酸化槽において好気性微生物反応で生成された硝酸塩を脱窒槽に戻して、嫌気性又は通性嫌気性微生物反応で脱窒素する方式で、循環法による硝化・脱窒を行うことができる。膜分離高負荷脱窒素槽の場合、硝化脱窒素槽は嫌気部と好気部に分割され、生物浮遊法を採用し、活性汚泥や凝集汚泥の固液分離を限外ろ過膜で処理を行うことができる。 (G) Nitrification denitrification tank You may provide the nitrification denitrification tank which nitrifies and denitrifies the dehydration separation water from a dehydration apparatus. Circulating nitrification / denitrification tanks, high-load denitrification tanks, and membrane separation-type high-load nitrification / denitrification tanks generally used in water treatment facilities and the like can be used without limitation. In the case of a circulation type nitrification denitrification tank, two tanks may be provided: a denitrification tank in an anaerobic environment and a nitrification tank in an aerobic environment by aeration. For example, it is possible to perform nitrification / denitrification by the circulation method by returning the nitrate produced by the aerobic microbial reaction in the nitrification tank to the denitrification tank and denitrifying by the anaerobic or facultative anaerobic microbial reaction. . In the case of a membrane separation high-load denitrification tank, the nitrification denitrogenation tank is divided into an anaerobic part and an aerobic part, adopts a biological suspension method, and performs solid-liquid separation of activated sludge and coagulated sludge with an ultrafiltration membrane. be able to.
　（Ｈ）希釈液供給配管
　硝化脱窒素槽からの処理水を曝気処理後の消化汚泥に添加する希釈液供給配管を備えていてもよい。希釈液供給配管は、曝気槽と凝集槽とを連結する配管に連結されていることが好ましい。希釈液供給配管には、脱水槽からの脱水分離水を送液する配管が連結されていてもよい。 (H) Diluent supply piping You may provide the diluent supply piping which adds the treated water from a nitrification denitrification tank to the digested sludge after an aeration process. It is preferable that the diluent supply pipe is connected to a pipe that connects the aeration tank and the aggregation tank. A pipe for feeding dehydrated separated water from the dehydration tank may be connected to the diluent supply pipe.
　（Ｉ）好気性微生物群含有汚泥供給配管
　硝化脱窒素槽からの好気性微生物群含有汚泥を汚泥引き抜きポンプで引き抜いて、曝気槽又は曝気槽に流入する前の難脱水性消化汚泥に添加する好気性微生物群含有汚泥供給配管を備えていてもよい。好気性微生物群含有汚泥供給配管は、嫌気性処理槽と曝気槽とを連結する配管に連結されていることが好ましい。 (I) Aerobic microorganism group-containing sludge supply piping The aerobic microorganism group-containing sludge from the nitrification denitrification tank is extracted with a sludge extraction pump and added to the aeration tank or the hardly dehydrated digested sludge before flowing into the aeration tank. An aerobic microorganism group-containing sludge supply pipe may be provided. The aerobic microorganism group-containing sludge supply pipe is preferably connected to a pipe connecting the anaerobic treatment tank and the aeration tank.
　次に、実施例及び比較例により、本発明を具体的に説明する。 Next, the present invention will be specifically described with reference to examples and comparative examples.
　［実施例１］
　表１に示すメタン発酵汚泥（難脱水性消化汚泥）を用いて、表２に示す８通りの処理試験を行って曝気処理による脱水性改善効果を確認した。曝気処理では、２０リットルタンクにメタン発酵汚泥１２リットルを投入し、温度３０℃、曝気強度０．２５ｍ３／（ｍ３・分）で連続曝気した。汚泥中のＤＯ濃度は１．０ｍｇ／Ｌ以下であった。試験４では、活性汚泥の余剰濃縮汚泥（ｐＨ７．６、ＳＳ　１３，７００ｍｇ／Ｌ、ＮＨ４－Ｎ　１．４ｍｇ／Ｌ）１.０リットルを投入して連続曝気した。比較のため、熱処理、水酸化ナトリウムによるアルカリ処理、及び硫酸による酸処理での脱水性改善効果も確認した。 [Example 1]
Using the methane fermented sludge (non-dewatered digested sludge) shown in Table 1, eight treatment tests shown in Table 2 were conducted to confirm the effect of improving the dehydration by aeration treatment. In the aeration process, 12 liters of methane fermentation sludge was put into a 20 liter tank, and continuous aeration was performed at a temperature of 30 ° C. and an aeration intensity of 0.25 m 3 / (m 3 · min). The DO concentration in the sludge was 1.0 mg / L or less. In Test 4, 1.0 liter of surplus concentrated sludge (pH 7.6, SS 13,700 mg / L, NH 4 -N 1.4 mg / L) of activated sludge was added and aerated continuously. For comparison, the effect of improving the dehydration by heat treatment, alkali treatment with sodium hydroxide, and acid treatment with sulfuric acid was also confirmed.
　熱処理は、１リットル三角フラスコにメタン発酵汚泥５００ｍＬを投入し、ウォーターバス（温度５０℃又は８０℃）で２時間、熱処理した（比較試験１及び２）。 In the heat treatment, 500 mL of methane fermentation sludge was put into a 1-liter Erlenmeyer flask and heat-treated for 2 hours in a water bath (temperature 50 ° C. or 80 ° C.) (Comparative tests 1 and 2).
　酸処理は、１リットル三角フラスコにメタン発酵汚泥５００ｍＬを投入し、５％濃度の硫酸溶液でｐＨ６に調整後、室温で６時間静置した（比較試験３）。 In the acid treatment, 500 mL of methane fermentation sludge was charged into a 1 liter Erlenmeyer flask, adjusted to pH 6 with a 5% strength sulfuric acid solution, and allowed to stand at room temperature for 6 hours (Comparative Test 3).
　アルカリ処理は、酸処理と同様、１リットル三角フラスコにメタン発酵汚泥５００ｍＬを投入し、１０％濃度の水酸化ナトリウム水溶液でｐＨ９に調整後、室温で６時間静置した（比較試験４）。 In the alkali treatment, 500 ml of methane fermentation sludge was charged into a 1 liter Erlenmeyer flask, adjusted to pH 9 with a 10% strength aqueous sodium hydroxide solution, and allowed to stand at room temperature for 6 hours (Comparative Test 4).
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
各分析項目は以下の分析方法に拠った。
・ＴＳ（Total solids、全蒸発残留物）；105℃蒸発残留物重量（JIS K 0102）
・ＶＳ（Volatile total solids、強熱減量）；600℃強熱減量（JIS K 0102）
・ＳＳ（Suspended solids、懸濁物質）；遠心分離機による回転数3,000rpm,10分間での沈殿物重量（JIS K 0102）
・ＶＳＳ（Volatile suspended solids、揮発性懸濁物質）；懸濁物質の600℃強熱減量（JIS K 0102）
・Ｍアルカリ度；遠心分離機による回転数3,000rpm,3分間での上澄液を0.1mol/Lの塩酸溶液でpH4.8まで滴定（下水試験方法）
・コロイド荷電量；汚泥の表面荷電量、コロイド滴定法により当量を測定（下水試験方法）
・粗浮遊物含有量；呼び寸法７４μｍふるいでの残留物の強熱減量分析（下水試験方法）
・汚泥粘度；Ｂ型回転粘度計を用いて３０℃で測定（下水試験方法）
・脱水試験；カチオン性高分子凝集剤エバグロースCS-374Dを用いた。脱水試験はベルトプレス式脱水機を用いた（ろ布緊張力４．９ｋＮ／ｍ、ろ布スピード１．０ｍ／分）。
・粘り感；脱水汚泥を掌で触った際の汚泥粘着性（粘り感）を３段階評価（なし：さらさらで粘り感なし、弱：粘り感ややあり、強：掌に付着する強い粘り感あり） Each analysis item was based on the following analysis method.
・ TS (Total solids, total evaporation residue); 105 ° C evaporation residue weight (JIS K 0102)
・ VS (Volatile total solids, loss on ignition); 600 ° C loss on ignition (JIS K 0102)
・ SS (Suspended solids, suspended matter); 3,000rpm, sediment weight in 10 minutes by centrifuge (JIS K 0102)
・ VSS (Volatile suspended solids); Loss on ignition of suspended materials at 600 ℃ (JIS K 0102)
・ M alkalinity; titration of supernatant at pH 4.8 with 0.1 mol / L hydrochloric acid solution at 3,000 rpm for 3 minutes using a centrifuge (sewage test method)
・ Colloid charge amount: Sludge surface charge amount, equivalent amount measured by colloid titration method (sewage test method)
・ Rough suspended matter content: Analysis of loss on ignition of residue in sieve with nominal size of 74μm (sewage test method)
・ Sludge viscosity: measured at 30 ° C using a B-type rotational viscometer (sewage test method)
Dehydration test: Cationic polymer flocculant Ebagulose CS-374D was used. In the dehydration test, a belt press type dehydrator was used (filter cloth tension force 4.9 kN / m, filter cloth speed 1.0 m / min).
-Stickiness: 3 levels of sludge adhesion (stickiness) when dehydrated sludge is touched with palm (None: smooth and no stickiness, weak: stickiness, somewhat strong, strong: strong stickiness on the palm )
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　［実施例２］
　表１に示すメタン発酵汚泥を用いて、曝気強度０．１ｍ３／（ｍ３・分）、０．２ｍ３／（ｍ３・分）、０．３ｍ３／（ｍ３・分）の３系列で連続曝気処理し、汚泥粘度の経時的変化を調べた。曝気処理時の汚泥温度は２２～２７℃、ＤＯ濃度は１．０ｍｇ／Ｌ以下であった。
試験結果を表４及び図５に示す。曝気強度に比例して、また、処理時間と共に汚泥粘度は低下することが分かった。 [Example 2]
Using the methane fermentation sludge shown in Table 1, aeration intensity of 0.1 m 3 / (m 3 · min), 0.2 m 3 / (m 3 · min), 0.3 m 3 / (m 3 · min) 3 Continuous aeration treatment was performed in series, and the change in sludge viscosity over time was examined. The sludge temperature during the aeration treatment was 22 to 27 ° C., and the DO concentration was 1.0 mg / L or less.
The test results are shown in Table 4 and FIG. It was found that the sludge viscosity decreases in proportion to the aeration intensity and with the treatment time.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　実施例１および実施例２の試験結果より、メタン発酵汚泥を曝気処理することで汚泥粘度は低下し、脱水性が改善されると言える。特に、曝気強度０．３ｍ３／（ｍ３・分）の場合には、わずか４時間で汚泥粘度（３０℃）が２００ｍＰａ・ｓ未満となり、１８時間で１００ｍＰａ・ｓ未満となる。一方、曝気時間が長くなると再び汚泥粘度が上昇する傾向が見られるため、曝気時間は４時間～８０時間、好ましくは４時間～４８時間、より好ましくは１８時間～４８時間程度、特に好ましくは２０時間～３０時間である。曝気強度が０．２ｍ３／（ｍ３・分）の場合にも同様の傾向が認められ、汚泥粘度が２００ｍＰａ・ｓ未満を達成する曝気時間は１５時間～８０時間であり、曝気時間としては１８時間～５０時間がより好ましい。曝気強度が０．１ｍ３／（ｍ３・分）の場合には、汚泥粘度２００ｍＰａ・ｓ未満を達成するまでに１９時間程度が必要となり、曝気時間は長くなる傾向が認められ、４８時間程度で汚泥粘度１００ｍＰａ・ｓ以下となる。いずれの曝気強度においても曝気時間を３０時間より長期化しても汚泥粘度低下効果はほぼ一定となる。したがって、本実施例によれば、曝気強度０．２ｍ３／（ｍ３・分）～０．３ｍ３／（ｍ３・分）、曝気時間４～４８時間、好ましくは１０～４０時間程度が、難脱水性消化汚泥の粘度低下に極めて効果的であるといえる。 From the test results of Example 1 and Example 2, it can be said that by subjecting the methane fermentation sludge to aeration treatment, the sludge viscosity is lowered and the dewaterability is improved. In particular, when the aeration intensity is 0.3 m 3 / (m 3 · min), the sludge viscosity (30 ° C.) is less than 200 mPa · s in just 4 hours and less than 100 mPa · s in 18 hours. On the other hand, since the sludge viscosity tends to increase again as the aeration time becomes longer, the aeration time is 4 to 80 hours, preferably 4 to 48 hours, more preferably about 18 to 48 hours, and particularly preferably 20 hours. Time to 30 hours. The same tendency is observed when the aeration intensity is 0.2 m 3 / (m 3 · min), and the aeration time for achieving the sludge viscosity below 200 mPa · s is 15 to 80 hours. 18 hours to 50 hours is more preferable. When the aeration intensity is 0.1 m 3 / (m 3 · min), it takes about 19 hours to achieve a sludge viscosity of less than 200 mPa · s, and the aeration time tends to be long, and about 48 hours are recognized. Thus, the sludge viscosity becomes 100 mPa · s or less. In any aeration intensity, even if the aeration time is longer than 30 hours, the sludge viscosity reducing effect is almost constant. Therefore, according to this example, the aeration intensity is 0.2 m 3 / (m 3 · min) to 0.3 m 3 / (m 3 · min), the aeration time is 4 to 48 hours, preferably about 10 to 40 hours. It can be said that it is extremely effective in reducing the viscosity of hardly dewatered digested sludge.
　［実施例３］
　（ａ）ＴＳ濃度３０ｇ／Ｌ、ＳＳ濃度１８ｇ／Ｌ、（ｂ）ＴＳ濃度３８ｇ／Ｌ、ＳＳ濃度１９ｇ／Ｌ、（ｃ）ＴＳ濃度４４ｇ／Ｌ、ＳＳ濃度３０ｇ／Ｌの３種類の高濃度消化（メタン発酵）汚泥を用いて、曝気強度０．２４ｍ３／（ｍ３・分）の条件で連続曝気処理し、汚泥粘度（３０℃）の経時的変化を調べた。ＤＯ濃度は１．０ｍｇ／Ｌ以下であった。試験結果を表５及び図６に示す。メタン発酵汚泥のＴＳ濃度４４ｇ／Ｌ、汚泥粘度１６００ｍＰａ・ｓの高濃度汚泥でも、２４時間の曝気処理によって２００ｍＰａ・ｓにまで汚泥粘度が低下することが分かった。 [Example 3]
(A) TS concentration 30 g / L, SS concentration 18 g / L, (b) TS concentration 38 g / L, SS concentration 19 g / L, (c) TS concentration 44 g / L, SS concentration 30 g / L. Digested (methane fermentation) sludge was subjected to continuous aeration treatment under the condition of aeration intensity of 0.24 m 3 / (m 3 · min), and the change with time in sludge viscosity (30 ° C.) was examined. The DO concentration was 1.0 mg / L or less. The test results are shown in Table 5 and FIG. It was found that even with high concentration sludge having a TS concentration of 44 g / L of methane fermentation sludge and a sludge viscosity of 1600 mPa · s, the sludge viscosity is reduced to 200 mPa · s by aeration treatment for 24 hours.
　汚泥（ａ）の曝気時間０（ｈ）、６（ｈ）及び１２（ｈ）の各試料について、ＧＰＣ（ゲルパーミエーションクロマトグラフ）による分子量分布測定を行った。汚泥試料を１０倍希釈後、０．４５μｍフィルターでろ過したろ液試料を分離カラム（東ソー製ＴＳＫｇｅｌ　ＧＭＰＷＸＬ）に導入し、ＲＩ検出器（示差屈折率検出）でＧＰＣ分析を行った。高分子物質の標準物質としてプルラン（平均分子量２３５万、１０．７万、０．６万の３種類）を用いた。分析条件を下記表５に示す。 The molecular weight distribution measurement by GPC (gel permeation chromatograph) was performed for each sample of aeration time 0 (h), 6 (h) and 12 (h) of sludge (a). After the sludge sample was diluted 10 times, the filtrate sample filtered through a 0.45 μm filter was introduced into a separation column (TSKgel GMPWXL manufactured by Tosoh Corporation), and GPC analysis was performed with an RI detector (differential refractive index detection). Pullulan (three types with average molecular weights of 23.5 million, 107,000, and 66,000) was used as a standard material for the polymer material. The analysis conditions are shown in Table 5 below.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　分析結果のクロマトグラフを図７に示す。図中、（１）は曝気０時間（ｈｒ）の試料、（２）は曝気６時間（ｈｒ）の試料、（３）は曝気１２時間（ｈｒ）の試料である。なお、図７はすべての結果を比較するために便宜的に並べて示しており、曝気１２時間（ｈｒ）の試料が最も高い位置にあるが測定値が高いことを示すものではない。保持時間（Retention time）５分～１０分のＲＩ強度（RI Intensity)をベースラインとした場合のＲＩ強度差でピーク強度の高低を認定した。 The chromatograph of the analysis results is shown in FIG. In the figure, (1) is a sample for aeration 0 hours (hr), (2) is a sample for aeration 6 hours (hr), and (3) is a sample for aeration 12 hours (hr). FIG. 7 shows all the results side by side for the sake of convenience, and does not indicate that the measured value is high although the sample for aeration 12 hours (hr) is at the highest position. The peak intensity was recognized based on the difference in RI intensity when the RI intensity (Retention Intensity) of 5 to 10 minutes was used as the baseline.
　分析結果では、保持時間（Retention time）約１３分～１４分における高分子画分ピークは、曝気時間が長くなるほどＲＩ強度が低くなることから、曝気処理によって高分子物質が分解されていることがわかる。また、いずれの汚泥試料においても、保持時間（Retention time）約１８～１９分に大きなピークが認められる中、曝気０時間（ｈｒ）試料、曝気６時間（ｈｒ）試料では分子量２３５万付近（プルラン換算）の物質が多く存在するのに対して、曝気１２時間（ｈｒ）試料では分子量１００万付近（プルラン換算）の物質が多く存在しており、曝気処理によって高分子物質が低分子化されていると言える。そして、曝気１２時間（ｈｒ）試料の保持時間（Retention time）約１９分のピークは、曝気０時間（ｈｒ）試料や６時間（ｈｒ）試料よりも鋭利となっていることから、曝気０時間（ｈｒ）試料や曝気６時間（ｈｒ）試料中の高分子物質の分解が進行していることが分かる。 According to the analysis results, the polymer fraction peak at a retention time of about 13 to 14 minutes has a lower RI intensity as the aeration time becomes longer. Recognize. In addition, in each sludge sample, a large peak is observed at a retention time of about 18 to 19 minutes. In the case of an aeration sample (hr) and an aeration sample (6 hours), the molecular weight is around 2.35 million (pullulan). In contrast, there are many substances with a molecular weight of around 1 million (in pullulan conversion) in the aerated 12-hour (hr) sample, and a high molecular weight material is reduced by aeration treatment. I can say that. And the peak of retention time (Retention time) of about 19 minutes for the aerated 12 hours (hr) sample is sharper than that of the aerated 0 hour (hr) sample and 6 hours (hr) sample. (Hr) It can be seen that the decomposition of the polymer substance in the sample and the aeration sample for 6 hours (hr) is proceeding.
　表６に曝気処理時間と消化汚泥の粘度との関係、表７に曝気処理時間と分子量との関係を示す。 Table 6 shows the relationship between the aeration treatment time and the viscosity of the digested sludge, and Table 7 shows the relationship between the aeration treatment time and the molecular weight.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
　［実施例４］
　図２のフローシートに基づいて、表８に示す条件にて、種々の食品製造廃棄物を混合してメタン発酵処理を行った。曝気用気体として、原料受入ホッパ、破砕機、選別機、可溶化槽、堆肥化発酵槽などの処理設備からの高濃度臭気含有空気を吸引して使用し、曝気槽底部の散気装置から導入した。 [Example 4]
Based on the flow sheet of FIG. 2, various food manufacturing wastes were mixed and subjected to methane fermentation treatment under the conditions shown in Table 8. As aeration gas, high-concentration odor-containing air from processing equipment such as raw material receiving hopper, crusher, sorter, solubilization tank, composting fermenter, etc. is sucked in and introduced from the diffuser at the bottom of the aeration tank did.
　曝気槽ブロワ運転は、図４に示す制御装置系統図に基づいて、メタン発酵槽の汚泥粘度７２０ｍＰａ・ｓ、曝気槽の汚泥粘度１０５ｍＰａ・ｓでの初期設定時を基準とし、メタン発酵槽撹拌機の初期電流設定の５％以上が検出された際にブロワ強度を３％ずつ段階的に増大させて曝気速度の調整を行う自動制御とした。メタン発酵汚泥及び曝気処理後の汚泥の性状を表９に示す。 The aeration tank blower operation is based on the control device system diagram shown in FIG. 4 and is based on the initial setting when the sludge viscosity of the methane fermentation tank is 720 mPa · s and the sludge viscosity of the aeration tank is 105 mPa · s. When the initial current setting of 5% or more is detected, automatic control is performed to adjust the aeration rate by gradually increasing the blower intensity by 3%. Table 9 shows the properties of methane fermentation sludge and sludge after aeration.
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
　次に、曝気処理後の消化汚泥に凝集剤を添加した後、脱水処理した。脱水処理（１）ではカチオン系高分子凝集剤（水ｉｎｇ（株）エバグロースCS-374D）と無機凝集剤（ポリ鉄）を併用し、脱水処理（２）及び（３）では高分子凝集剤のみ添加した。脱水処理（３）は比較試験で、曝気処理をしなかった難脱水性消化汚泥での脱水試験結果である。脱水処理（１）～（３）における凝集剤添加率及び脱水処理後の脱水ケーキ性状及び時間当たりの固形物処理量を表１０に示す。 Next, a flocculant was added to the digested sludge after the aeration treatment, followed by dehydration treatment. In the dehydration process (1), a cationic polymer flocculant (Watering Ebagulose CS-374D) and an inorganic flocculant (polyiron) are used in combination, and in the dehydration processes (2) and (3), only the polymer flocculant is used. Added. Dehydration treatment (3) is the result of a dehydration test on a hardly dehydrated digested sludge that was not aerated in a comparative test. Table 10 shows the flocculant addition rate, dehydrated cake properties after dehydration, and solids throughput per time in dehydration (1) to (3).
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
　［実施例５］
　図３のフローシートに基づいて、硝化脱窒素工程から得られる活性汚泥の余剰濃縮汚泥（好気性微生物群含有汚泥）を曝気槽に導入した点を除いて実施例４と同様に処理を行った。結果を表１１及び１２に示す。 [Example 5]
Based on the flow sheet of FIG. 3, the same treatment as in Example 4 was performed, except that the activated sludge surplus concentrated sludge (aerobic microorganism group-containing sludge) obtained from the nitrification / denitrification step was introduced into the aeration tank. . The results are shown in Tables 11 and 12.
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000012
　以上のように、本発明によれば、有機性廃棄物を高濃度でメタン発酵処理した難脱水性消化汚泥に対して、脱水処理の前に曝気処理を施すことで汚泥の粘度を大幅に低下させることができ、凝集性能及び脱水効率を向上させることができる。本発明の処理方法によれば、凝集剤の添加量を低減でき（低薬注率）、安定的に短時間で高濃度消化汚泥の脱水処理が可能となる。本発明によって得られた含水率８２％以下の脱水ケーキは、従来の脱水ケーキと比較して低含水率で、粘着性がなく、特殊な不快臭もないことから、コンポスト、炭化、燃料化などの再資源化にも好適である。 As described above, according to the present invention, the viscosity of sludge is greatly reduced by subjecting the hardly-dehydrated digested sludge obtained by subjecting organic waste to high-concentration methane fermentation to aeration before dehydration. It is possible to improve coagulation performance and dewatering efficiency. According to the treatment method of the present invention, the amount of the flocculant added can be reduced (low chemical injection rate), and the high-concentration digested sludge can be dehydrated stably in a short time. The dehydrated cake having a moisture content of 82% or less obtained by the present invention has a low moisture content, is not sticky, and has no special unpleasant odor compared to conventional dehydrated cakes. It is also suitable for recycling.

Claims (13)

  1. 嫌気性処理後の有機性汚泥を処理する方法であって、
    当該有機性汚泥は、２５ｇ／Ｌ以上のＴＳ濃度と、当該ＴＳ濃度よりも５ｇ／Ｌ以上少ないＳＳ濃度と、を有する難脱水性消化汚泥であり、
    当該消化汚泥を脱水処理する前に、当該難脱水性消化汚泥に対して酸素含有気体を通気して曝気処理を行ない、当該難脱水性消化汚泥の粘度を低減させることを特徴とする有機性汚泥の処理方法。     A method for treating organic sludge after anaerobic treatment,
    The organic sludge is a hardly dewaterable digested sludge having a TS concentration of 25 g / L or more and an SS concentration of 5 g / L or less less than the TS concentration,
    Before dewatering the digested sludge, an oxygen-containing gas is aerated to the hardly dehydrated digested sludge to perform aeration treatment, thereby reducing the viscosity of the hardly dehydrated digested sludge Processing method.
  2. 前記曝気処理は、曝気処理後の難脱水性消化汚泥の粘度が、下水試験方法に定められたＢ型回転粘度計による３０℃での測定で２００ｍＰａ・ｓ以下に低下するまで行うことを特徴とする請求項１に記載の有機性汚泥の処理方法。 The aeration treatment is performed until the viscosity of the hardly dehydrated digested sludge after the aeration treatment is lowered to 200 mPa · s or less as measured at 30 ° C. by a B-type rotational viscometer defined in the sewage test method. The processing method of the organic sludge of Claim 1 to do.
  3. 前記曝気処理は、０．１ｍ３／（ｍ３・分）以上の曝気強度にて４時間以上４８時間以下の曝気時間で行うことを特徴とする請求項１又は２に記載の有機性汚泥の処理方法。 3. The organic sludge according to claim 1, wherein the aeration treatment is performed at an aeration intensity of 0.1 m 3 / (m 3 · min) or more and an aeration time of 4 hours or more and 48 hours or less. Processing method.
  4. 前記曝気強度は０．２ｍ３／（ｍ３・分）以上であることを特徴とする請求項３に記載の有機性汚泥の処理方法。 The method for treating organic sludge according to claim 3, wherein the aeration intensity is 0.2 m 3 / (m 3 · min) or more.
  5. 前記曝気処理に用いる酸素含有気体は、空気、又は処理対象となる有機性汚泥が形成される処理施設内で発生する臭気成分を含む空気であることを特徴とする請求項１～４のいずれか１に記載の有機性汚泥の処理方法。 5. The oxygen-containing gas used for the aeration treatment is air or air containing an odor component generated in a treatment facility where organic sludge to be treated is formed. The method for treating organic sludge according to 1.
  6. 前記曝気処理を行う前に、難脱水性消化汚泥に、好気性微生物群を含む汚泥を添加することを特徴とする請求項１～５のいずれか１項に記載の有機性汚泥の処理方法。 The method for treating organic sludge according to any one of claims 1 to 5, wherein sludge containing an aerobic microorganism group is added to the hardly dehydrated digested sludge before the aeration treatment.
  7. 前記曝気処理は、前記難脱水性消化汚泥中の溶存酸素濃度を１．０ｍｇ／Ｌ以下に維持して行うことを特徴とする請求項１～６のいずれか１に記載の有機性汚泥の処理方法。 The treatment of organic sludge according to any one of claims 1 to 6, wherein the aeration treatment is performed while maintaining a dissolved oxygen concentration in the hardly dehydrated digested sludge at 1.0 mg / L or less. Method.
  8. 前記曝気処理後の消化汚泥に、６．０ｇ／Ｌ以下のＴＳ濃度を有する希釈液を添加して希釈した後、脱水処理することを特徴とする請求項１～７のいずれか１項に記載の有機性汚泥の処理方法。 The dehydrated treatment is carried out after adding and diluting a diluted solution having a TS concentration of 6.0 g / L or less to the digested sludge after the aeration treatment. Of organic sludge.
  9. 前記曝気処理後の消化汚泥に凝集剤を添加して凝集汚泥を形成し、当該凝集汚泥を脱水処理し、脱水処理により発生する脱水分離水を前記希釈液として用いることを特徴とする請求項８に記載の有機性汚泥の処理方法。 9. A flocculant is added to the digested sludge after the aeration treatment to form agglomerated sludge, the agglomerated sludge is dehydrated, and dehydrated separated water generated by the dehydration treatment is used as the diluent. The processing method of the organic sludge as described in 2.
  10. 前記凝集剤としてポリ硫酸第二鉄、塩化第二鉄、ＰＡＣ（ポリ塩化アルミニウム）又は硫酸バンドを用いることを特徴とする請求項９に記載の有機性汚泥の処理方法。 The method for treating organic sludge according to claim 9, wherein polycoferric sulfate, ferric chloride, PAC (polyaluminum chloride) or a sulfuric acid band is used as the flocculant.
  11. ２５ｇ／Ｌ以上のＴＳ濃度と、当該ＴＳ濃度よりも５ｇ／Ｌ以上少ないＳＳ濃度と、を有する難脱水性消化汚泥を形成する嫌気性処理槽と、
    当該難脱水性消化汚泥に酸素含有気体を曝気させる曝気槽と、
    曝気処理後の消化汚泥に凝集剤を添加して凝集汚泥を形成する凝集槽と、
    当該嫌気性処理槽又は当該凝集槽の撹拌装置の撹拌抵抗に応じて当該曝気槽に供給する酸素含有気体の曝気速度を調整する制御装置と、
    当該凝集汚泥を脱水する脱水装置と、
    を具備することを特徴とする、有機性汚泥の処理装置。     An anaerobic treatment tank for forming a hardly dehydrated digested sludge having a TS concentration of 25 g / L or more and an SS concentration of 5 g / L or less less than the TS concentration;
    An aeration tank for aspirating oxygen-containing gas to the hardly dehydrated digested sludge;
    A coagulation tank that forms coagulated sludge by adding a coagulant to the digested sludge after aeration treatment;
    A control device that adjusts the aeration rate of the oxygen-containing gas supplied to the aeration tank according to the stirring resistance of the stirring device of the anaerobic treatment tank or the aggregation tank;
    A dehydrator for dewatering the agglomerated sludge;
    An organic sludge treatment apparatus, comprising:
  12. 前記脱水装置からの脱水分離水を硝化脱窒素する硝化脱窒素槽と、
    当該硝化脱窒素槽からの処理水を前記曝気処理後の消化汚泥に添加する希釈液供給配管をさらに具備することを特徴とする、請求項１１に記載の有機性汚泥の処理装置。     A nitrification / denitrification tank for nitrification / denitrification of the dewatered separated water from the dehydrator;
    12. The organic sludge treatment apparatus according to claim 11, further comprising a diluent supply pipe for adding treated water from the nitrification denitrification tank to the digested sludge after the aeration treatment.
  13. 前記硝化脱窒素槽からの好気性微生物群含有汚泥を前記曝気槽又は前記曝気槽に流入する前の難脱水性消化汚泥に添加する好気性微生物群含有汚泥供給配管をさらに具備することを特徴とする、請求項１２に記載の有機性汚泥の処理装置。 An aerobic microorganism group-containing sludge supply pipe for adding the aerobic microorganism group-containing sludge from the nitrification denitrification tank to the aeration tank or the hardly dehydrated digested sludge before flowing into the aeration tank, The organic sludge treatment apparatus according to claim 12.
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