JPH091179A - Anaerobic digestion treatment of highly concentrated organic waste water and equipment therefor - Google Patents

Abstract

PURPOSE: To enable the treatment by using an upflow anaerobic sludge blanket process equipment (UASB) or fixed bed treating equipment at the time of treating highly concentrated organic waste water contg. biodegradable organic solid matter. CONSTITUTION: In this treatment, waste water 10 contg. organic solid matter is separated by sedimentation in a sedimentation tank 14 and thereafter, a supernatant liquid A having a lesser organic solid matter content is treated by using an anaerobic treating equipment 18 such as upflow anaerobic sludge blanket process equipment (UASB), fixed bed treating equipment, or the like to subject the liquid A to anaerobic digestion treatment. At the same time, a liquid concentrate C of sedimented solid matter, that contains the organic solid matter separated by the sedimentation in the sedimentation tank 14, is subjected to solubilization treatment at a high temp. in a solubilization vessel 24. Thereafter, the resulting solubilization product, together with the waste water 10 contg. organic solid matter, is separated by sedimentation in the sedimentation tank 14 and then introduced into the anaerobic treating equipment 18, or directly introduced into the treating equipment 18.

Description

Detailed Description of the Invention

[0001]

The present invention relates to organic sludge, for example,
Biodegradable organic substances such as raw sludge and biological sludge discharged from sewage treatment processes such as sewage treatment plants and human waste treatment plants, and organic high-concentration sludge discharged from wastewater treatment processes such as food plants and chemical plants. TECHNICAL FIELD The present invention relates to an anaerobic digestion treatment method for high-concentration organic wastewater containing volatile solids and an anaerobic digestion treatment apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, when treating high-concentration organic wastewater containing biodegradable organic solids such as starch factory waste liquid, beer factory waste liquid, acid fermentation waste liquid, etc., An anaerobic digestion method is known in which a methane fermentation tank maintains a medium temperature of 30 to 37 ° C. or a high temperature of 50 to 55 ° C. to perform methane fermentation and convert it into a gas such as methane. In this case, as the methane fermentation tank, a fixed bed type treatment device and an upflow anaerobic sludge bed treatment device (hereinafter referred to as “UASB”) are used. The fixed-bed type treatment device is a device that fixes microorganisms on a carrier such as beads and treats them, whereas the UA
As shown in FIG. 2, the SB is a device that forms and processes granules by utilizing the self-granulating action of microorganisms.

By the way, UASB is preferable because it can maintain a large amount of microorganisms, has a large contact area per unit volume, has good contact efficiency, and can take a large load, but organic wastewater contains a large amount of solid content (SS). In case of UASB,
In some cases, the granules flow along with the solid matter, and the granules cannot be maintained in the system. For this reason, as shown in FIG. 4, the organic solid-containing wastewater is usually separated in a settling tank, and the supernatant is introduced into the UASB for treatment. However, in this case, since the precipitated solids concentrate (sludge) containing the organic solids separated and separated in the settling tank is processed through steps such as concentration, digestion, dehydration, composting and incineration, such treatment It was troublesome and costly, which was not preferable.

Therefore, when the organic wastewater contains a large amount of solids (SS), a fixed bed type treatment apparatus is used. However, in the fixed bed type treatment apparatus, the wastewater linear velocity in the tank is extremely high. Due to the slowness, solid matter with high sedimentation cannot be discharged together with the wastewater, and the solid matter is trapped in the gaps of the carrier,
It causes clogging and blocks the passage of liquid. As the number of the clogging points increases, the passage of the liquid component decreases, and the liquid component flows only in the non-clogging places, so that the liquid and the carrier are not sufficiently contacted. Will occur. Therefore, in a methane fermentation tank for the purpose of gasifying a solubilizable organic substance, due to the short circuit phenomenon of the liquid component, the retention time of the waste water is shortened and the treatment efficiency is extremely lowered. Therefore, in this case, although the clogging is eliminated by backwashing or the like, the processing is stopped during the backwashing, and a large amount of cost is required. For this reason, as shown in FIG. 5, a method of solubilizing organic solid-containing wastewater by a physicochemical method such as a hot alkali method or an enzyme addition method has been proposed, but the chemical cost is high. On the contrary, the cost was high, which was not preferable.

Therefore, in view of the above situation, the present invention, when treating a high-concentration organic wastewater containing a biodegradable organic solid, contains the solid content (S) contained in the organic wastewater.
Anaerobic digestion treatment of high-concentration organic wastewater that can be treated using an upflow anaerobic sludge bed treatment unit (UASB), which has good contact efficiency and large load by solubilizing S). It is an object to provide a method and a processing device therefor.

Further, in view of the above situation, the present invention provides a method for treating a high-concentration organic wastewater containing a biodegradable organic solid matter, wherein the solid content (S
(EN) A method for anaerobic digestion of high-concentration organic wastewater that can be processed with a fixed-bed-type processing device with a low backwash frequency by solubilizing S), and a processing device therefor. Also for the purpose.

[0007]

The method for anaerobic digestion of high-concentration organic wastewater and the treatment apparatus therefor according to the present invention have been devised to achieve the above-mentioned objects and objects. (1) to (13) of the above are the gist.

(1) An anaerobic digestion treatment device for high-concentration organic wastewater containing biodegradable organic solids, comprising: a settling tank for separating and separating organic solids-containing wastewater; An anaerobic treatment device for anaerobic digestion of a supernatant liquid containing a small amount of precipitated organic solids, and solubilization of a precipitated solid concentrate containing the organic solids separated and separated in the precipitation tank under high temperature conditions. It consists of a solubilization tank for processing,
An anaerobic digestion treatment device for high-concentration organic wastewater, characterized in that the solubilization treatment liquid solubilized in the solubilization tank is introduced into the anaerobic treatment device.

(2) The solubilization treatment liquid solubilized in the solubilization tank is introduced into the precipitation tank together with the organic solid-containing wastewater to separate the precipitate, and then introduced into the anaerobic treatment apparatus. An anaerobic digestion treatment device for high-concentration organic wastewater as described in (1) above.

(3) A heat exchanger for heating the concentrated precipitate solids separated and separated in the settling tank with the solubilization treatment liquid solubilized in the solubilization tank is transferred from the settling tank to the solubilization tank. An anaerobic digestion treatment device for high-concentration organic wastewater according to the above (1) or (2), characterized in that it is provided in a recirculating route.

(4) A methane gas combustion device for burning the methane gas generated in the anaerobic treatment device is provided, and a heating path for heating the solubilization tank by the heat generated by the methane gas combustion device. The anaerobic digestion treatment device for high-concentration organic wastewater according to any one of the above (1) to (3), characterized by being provided.

(5) The high-concentration organic substance according to any one of (1) to (4) above, wherein the anaerobic treatment device is an upflow anaerobic sludge bed treatment device (UASB). Anaerobic digestion treatment equipment for anaerobic wastewater.

(6) The above-mentioned (1) to (4), wherein the anaerobic treatment device is a fixed bed type treatment device.
An anaerobic digestion treatment device for high-concentration organic wastewater according to any one of 1.

(7) A method for anaerobic digestion of high-concentration organic wastewater containing biodegradable organic solid matter, wherein the organic solid matter-containing wastewater is precipitated and separated in a settling tank, and then the separated organic solid matter is separated. For the anaerobic digestion treatment of the supernatant liquid containing a small amount of substances in an anaerobic treatment device, and for the solubilization treatment of the precipitated solids concentrate containing the organic solids separated and separated in the precipitation tank under high temperature conditions. A method for anaerobic digestion of high-concentration organic wastewater, which comprises solubilizing in a solubilizing tank and introducing the solubilized solubilized treatment liquid into an anaerobic treatment apparatus.

(8) After the solubilized solubilized treatment liquid is precipitated and separated together with the organic solid-containing wastewater in a settling tank,
The method for anaerobic digestion of high-concentration organic wastewater according to (7) above, which is introduced into an anaerobic treatment apparatus.

(9) In the above-mentioned (7) or (8), the concentrated solid solution of the precipitated solid separated and separated in the settling tank is heated by the solubilized treatment solution solubilized in the solubilizing tank. A method for anaerobic digestion treatment of high-concentration organic wastewater as described.

(10) The solubilization tank is heated by the heat generated by burning the methane gas generated in the anaerobic treatment apparatus. (7) to (9) The method for anaerobic digestion of high-concentration organic wastewater according to.

(11) The high-concentration organic substance according to any one of (7) to (10) above, wherein the anaerobic treatment device is an upflow anaerobic sludge bed treatment device (UASB). Method for anaerobic digestion of organic wastewater.

(12) From the above (7) to (1), wherein the anaerobic treatment device is a fixed bed type treatment device.
The method for anaerobic digestion of highly concentrated organic wastewater according to any one of 0).

(13) The high-concentration organic material according to any one of (7) to (12) above, wherein the solubilization treatment is carried out under the condition that the temperature range is from 60 to 80 ° C. Method for anaerobic digestion of organic wastewater.

That is, as a result of intensive studies by the present inventors, after the separation and separation of the organic solid-containing wastewater, the upward flow anaerobic gas for anaerobic digestion of the supernatant liquid containing a small amount of organic solids. In addition to treating with the sludge sludge bed treatment device (UASB),
By subjecting the precipitated solid concentrate containing the separated organic solid to a solubilization treatment under high temperature conditions and introducing it into UASB,
The present invention has been completed by finding that the water quality can be applied to UASB that dislikes solids.

After the organic solid-containing wastewater is separated by precipitation, the supernatant containing a small amount of organic solids is processed by a fixed bed type processing device for anaerobic digestion, and the separated organic matter is separated. By solubilizing the precipitated solid concentrate containing solids under high temperature conditions and introducing it into a fixed bed type processing device, it causes clogging, and solid matter with high sedimentability that requires backwashing is removed. The present invention has been completed by finding that the water quality can be applied to a fixed bed type treatment device which is disliked.

[0023]

EXAMPLES In the present invention, organic sludge, for example, raw sludge and biological sludge discharged from a sewage treatment process such as a sewage treatment plant and a human waste treatment plant, or a wastewater treatment process from a food factory, a chemical factory, etc. Drained starch factory effluent,
High-concentration organic wastewater containing biodegradable organic solids (hereinafter referred to as "raw wastewater") such as organic high-concentration sludge such as brewery wastewater and acid fermentation wastewater.

As shown in FIG. 1, the raw wastewater stored in these raw wastewater storage tanks 10 is introduced into a settling tank 14 via a route 12, and organic solid-containing wastewater is separated by sedimentation and settling. The separated supernatant A containing a small amount of organic solids is introduced into the upward flow anaerobic sludge bed treatment unit (UASB) 18 for anaerobic digestion treatment via a route 16. . In this case, as the UASB18, the one shown in FIG. 2 can be used, and the treated water B anaerobically treated by the UASB18 is further treated by the activated sludge method or the like if necessary according to the reference value of the discharge destination. After that, it will be discharged into sewage or rivers.

On the other hand, the precipitated solids concentrate C containing the organic solids separated and separated in the precipitation tank 14 is introduced into the solubilization tank 24 through the reflux path 20 and anaerobically or aerobically under high temperature conditions. Solubilization of organic sludge is performed. In this case, the inoculum of anaerobic or aerobic microorganisms used under high temperature conditions (thermophilic bacterium) is, for example, a microorganism cultivated from a conventional aerobic or anaerobic digestion tank or sewage treatment plant activated sludge surplus sludge. It is obtained by Also,
The optimum temperature of the solubilization tank 24 is preferably operated under conditions such that the temperature range is 50 to 90 ° C., but the organic solid matter contained in the precipitated solid concentrate C, which is the high temperature treatment target, is decomposed. Depending on the type of thermophilic bacterium used, for example, in the case of thermophilic bacterium separated from sewage surplus sludge, both solubilization reaction by microorganisms (thermophilic bacterium) and physicochemical thermal decomposition by heat At the same time, the temperature sludge under high temperature conditions is operated in the range of 60 to 80 ° C, preferably in the range of 70 ° C so that it can be efficiently and sufficiently produced. In any case, depending on the type of the microorganism, the solubilization reaction by the microorganism (thermophilic bacterium) and the physicochemical thermal decomposition by heat can both occur efficiently and sufficiently at a temperature of 50 to 90 ° C. The temperature may be set within the temperature range.

Further, as an apparatus for aerobically decomposing microorganisms in the solubilization tank 24, a conventional air diffuser is provided, and an apparatus for anaerobic microorganism decomposing is (1) ) A method of stirring by circulating the liquid in the tank,
(2) A method of stirring by circulating aeration of the produced gas,
(3) A method of installing a stirrer such as a stirring blade, and (4) having a means for fixing the active microorganisms, such as a means for efficiently contacting the activated microorganisms with the sludge to be treated can be used. . In this case, as the reaction tank, either a batch system or a continuous system can be used.

As described above, the solubilized treatment liquid D solubilized in the solubilization tank 24 passes through the route 26, the heat exchanger 28 provided in the reflux route 20, and the route 30. It is merged with 12 and introduced into the settling tank 14 together with the organic solid-containing wastewater to be separated for precipitation, and the processing cycle is repeated as described above. In the heat exchanger 28, the precipitated solid concentrate C separated and precipitated in the precipitation tank 14 is solubilized in the solubilization tank 24.
By heating with the solubilization treatment liquid D solubilized in
It is designed to minimize heat loss. Also, the solubilization tank
The solubilization treatment liquid D solubilized in 24 has a solid content (SS) of 3000 ppm or less so that it can be reloaded by the UASB18.

Further, the methane gas E generated in the UASB 18 is introduced into the methane gas combustor 34 via the path 32, and the heat generated by the combustion of the methane gas in the methane gas combustor 34 is solubilized in the solubilization tank via the heating path 36. It is configured to heat 24.

In this case, the methane gas combustion device 34 is not particularly limited, and a combustion device such as a natural ventilation type internal combustion type combustion tower equipped with an ordinary gas burner can be used. In this way, the energy of the heat radiation in the solubilization tank 24 is replenished by the combustion of the surplus methane generated by the anaerobic treatment in the UASB 18, so that it is very efficient in terms of energy.

Further, a part of the precipitated solids concentrate (sludge) containing the organic solids precipitated and separated in the settling tank 14 should be prevented from accumulating biodegradable solids or inorganic solids in the system. , Is appropriately discharged via the route 15, concentrated, dehydrated, and discarded. In this case, since the sludge discharged has passed through the solubilization tank 24 that is a high-temperature tank, it is a sludge with a small amount of dissolved gas and excellent sedimentation properties.
Concentrated dehydration treatment is easy.

FIG. 3 is a diagram showing the outline of a second embodiment of the anaerobic digestion treatment method for high-concentration organic wastewater and the anaerobic digestion treatment apparatus therefor according to the present invention.

This embodiment has basically the same structure as that of the first embodiment described above, and the same constituent members are designated by the same reference numerals. The difference from the first embodiment is that the solubilization treatment liquid D solubilized in the solubilization tank 24 in the first embodiment is passed through the path 26 to the heat exchanger 28 provided in the reflux path 20. Via the route 30, after being merged into the route 12 and introduced into the settling tank 14 together with the organic solid-containing wastewater to be separated by sedimentation, the upflow anaerobic sludge bed treatment device (U
In this embodiment, instead of being introduced into the ASB) 18, the solubilization treatment liquid D is directly introduced into the upward flow anaerobic sludge bed treatment device (UASB) 18 via the route 30 ′. Be different. That is, when the solubilization is sufficiently performed in the solubilization tank 24,
This is because there is no need to separate the precipitate.

In the first and second embodiments described above, the upflow anaerobic sludge bed treatment device (UASB) 18 was used as the anaerobic digestion treatment device, but a fixed bed treatment device should be used. In that case, since solid matter having a high sedimentation property that causes clogging does not flow in, the frequency of backwashing can be small and the operating efficiency can be increased.

Example 1 A jacket type cylindrical reaction tank in which a heat medium made of heat-resistant vinyl chloride having an inner diameter of 100 mm and a height of 1 m was circulated was used, and the temperature was 70
It was operated at 0 ° C., an air flow rate of 0.1 vvm, and a reaction liquid volume of 4 L. For the treatment waste liquid, use a sediment (sedimentation rate SV30 = 10%, solids concentration SS = 1.3%, volatile organic substance content ratio VSS / SS = 98%) obtained by separating and separating the starch factory wastewater for 30 minutes. 3.2 L of precipitated solid was added to 0.8 L of seed sludge. At a residence time of 2.5 days, about 60% of the insoluble starch solids were solubilized. A considerable amount of solid matter (2300 ppm as SS) remains in the supernatant of the sedimentation for 30 minutes, but these have a small particle size and hardly settled even when left standing for a long time. Although the possibility of causing clogging was extremely low, a comparison with the conventional method is shown in Table 1 below. As is clear from the results shown in Table 1, when the solubilization treatment was performed with thermophilic bacteria as in the present invention, the ratio of the immediate sedimentation solid matter that causes clogging in the fixed bed treatment apparatus was 1 / It turned out that it can be reduced to 2 or less.

[0035]

[Table 1]

[0036]

According to the method for anaerobic digestion of high-concentration organic wastewater and the treatment apparatus therefor according to the present invention, after the organic-solid-containing wastewater is separated by sedimentation, the supernatant containing less organic solids is obtained. For the anaerobic digestion of liquid, the anaerobic treatment equipment such as an upflow anaerobic sludge bed treatment equipment (UASB) or a fixed bed treatment equipment is used, and the sediment containing the separated organic solid is precipitated. The solid concentrate was solubilized under high temperature conditions, and it was separated by precipitation together with the organic solid-containing wastewater and introduced into the anaerobic treatment equipment. It is an extremely excellent invention that produces effects.

(1) When treating a high-concentration organic wastewater containing a biodegradable organic solid, the solid content (SS) in the organic wastewater to be treated is solubilized to a small amount, and even in UASB, An upflow anaerobic sludge bed treatment device (UASB) that does not allow granules to accompany solids and flow out, can maintain granules in the system, has good contact efficiency, and can take a large load.
Can be used for processing.

(2) Since the precipitated solids concentrate (sludge) containing the organic solids separated and separated in the settling tank has passed through the solubilization tank which is a high temperature tank, the dissolved gas is small and the sedimentation property is low. Since it is an excellent sludge, it can be easily concentrated and dehydrated, and cost can be reduced.

(3) When treating a high-concentration organic wastewater containing a biodegradable organic solid matter, the solid content in the organic wastewater to be treated is a highly sedimentable solid matter that causes clogging. Since it contains almost no liquid, there is no short circuit of liquid due to clogging.
Operations such as backwashing become unnecessary, and the processing efficiency does not decrease.

(4) A heat exchanger for heating the precipitated solid concentrate concentrated and separated in the settling tank with the solubilization treatment liquid solubilized in the solubilization tank is refluxed from the settling tank to the solubilization tank. With the structure provided in the path, it is possible to suppress heat loss as much as possible.

(5) A methane gas combustor for burning the methane gas generated in the anaerobic treatment apparatus is provided, and a heating path for heating the solubilization tank by the heat generated by the methane gas combustor is provided. The energy of the heat released in the solubilization tank will be supplemented by the combustion of the surplus methane generated by the anaerobic treatment in UASB, so it is very energy efficient.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an embodiment of an anaerobic digestion treatment method for high-concentration organic wastewater and an anaerobic digestion treatment apparatus therefor according to the present invention.

FIG. 2 is a schematic diagram of an upflow anaerobic sludge bed treatment device (UASB).

FIG. 3 is a diagram schematically showing a second embodiment of the anaerobic digestion treatment method for high-concentration organic wastewater and the anaerobic digestion treatment apparatus therefor according to the present invention.

FIG. 4 is a conventional upflow anaerobic sludge bed treatment device (U
FIG. 3 is a schematic view showing a usage state of ASB).

FIG. 5 is a schematic view showing a usage state of a conventional fixed bed type processing apparatus.

[Explanation of symbols]

 10 ... Raw wastewater storage tank 14 ... Settling tank 18 ... Upflow anaerobic sludge bed treatment device (UASB) 20 ... Reflux path 24 ... Solubilization tank 28 ... Heat exchanger 34 ... Methane gas combustor A ... Supernatant liquid B ... Treated water C ... Precipitated solid concentrate D ... Solubilized treatment liquid

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location C02F 9/00 504 C02F 9/00 504E 504A 11/04 11/04 Z (72) Inventor Hideki Yokoyama Kobe, Hyogo Prefecture 292, Minami-ochiai, Suma-ku, Yokohama

Claims (13)

[Claims] 1. An anaerobic digestion treatment apparatus for highly concentrated organic wastewater containing biodegradable organic solids, comprising: a settling tank for separating and separating the wastewater containing organic solids; An anaerobic treatment device for anaerobic digestion of the separated supernatant containing a small amount of organic solids, and a solubilization treatment of a precipitated solid concentrate containing the organic solids separated and separated in the precipitation tank under high temperature conditions. Anaerobic digestion of high-concentration organic wastewater, which is characterized in that it is configured to introduce a solubilization treatment liquid solubilized in the solubilization tank into an anaerobic treatment apparatus. Processing equipment. 2. The solubilization treatment liquid solubilized in the solubilization tank is introduced into a sedimentation tank together with the organic solid-containing wastewater to separate the precipitate, and then introduced into an anaerobic treatment apparatus. The anaerobic digestion treatment device for high-concentration organic wastewater according to claim 1. 3. A heat exchanger for heating the precipitated solid concentrate concentrated and separated in the settling tank with the solubilization treatment liquid solubilized in the solubilization tank is provided from the settling tank to the solubilization tank. The anaerobic digestion treatment apparatus for high-concentration organic wastewater according to claim 1 or 2, which is provided in a reflux path. 4. A methane gas combustor for combusting methane gas generated in the anaerobic treatment apparatus is provided, and a heating path for heating the solubilization tank by heat generated by the methane gas combustor is provided. The anaerobic digestion treatment device for high-concentration organic wastewater according to any one of claims 1 to 3, which is provided. 5. The high concentration organic wastewater anaerobic according to claim 1, wherein the anaerobic treatment device is an upflow anaerobic sludge bed treatment device (UASB). Digestion processing equipment. 6. The anaerobic digestion treatment device for high-concentration organic wastewater according to claim 1, wherein the anaerobic treatment device is a fixed bed treatment device. 7. A method for anaerobic digestion of high-concentration organic wastewater containing biodegradable organic solids, comprising separating organic solids-containing wastewater in a settling tank, and then separating the separated organic solids. An anaerobic digester is used for anaerobic digestion of a supernatant liquid containing less solid, and a solid precipitate concentrate containing an organic solid precipitated and separated in the precipitation tank is solubilized under high temperature conditions. A method for anaerobic digestion of high-concentration organic wastewater, which comprises introducing the solubilized solubilized treatment liquid into an anaerobic treatment apparatus after solubilization in a solubilization tank. 8. The high-concentration organic substance according to claim 7, wherein the solubilized treatment liquid thus solubilized is introduced into an anaerobic treatment apparatus after being precipitated and separated together with the organic solid-containing wastewater in a sedimentation tank. Method for anaerobic digestion of organic wastewater. 9. The high-concentration organic substance according to claim 7 or 8, wherein the precipitated solid matter concentrated liquid precipitated and separated in the precipitation tank is heated with the solubilization treatment liquid solubilized in the solubilization tank. Method for anaerobic digestion of organic wastewater. 10. The high temperature according to claim 7, wherein the solubilization tank is heated by heat generated by burning methane gas generated in the anaerobic treatment apparatus. Method for anaerobic digestion of concentrated organic wastewater. 11. The anaerobic treatment device is an upflow anaerobic sludge bed treatment device (UASB).
11. The anaerobic digestion treatment method for high-concentration organic wastewater according to any one of 1 to 10. 12. The method for anaerobic digestion treatment of high-concentration organic wastewater according to claim 7, wherein the anaerobic treatment apparatus is a fixed bed type treatment apparatus. 13. The anaerobic high-concentration organic wastewater according to claim 7, wherein the solubilization treatment is carried out under conditions such that the temperature range is 60 to 80 ° C. Digestion treatment method.