JP3152357B2 - Anaerobic treatment method and apparatus for high-concentration organic wastewater containing organic suspended matter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic suspended substance (S)
The present invention relates to a method and an apparatus for anaerobically treating wastewater containing S) at a high concentration.

[0002]

2. Description of the Related Art Conventionally, UASB (Upflood) has been used for anaerobic treatment of wastewater containing a high concentration of organic suspended solids (SS).
High efficiency anaerobic bioreactors such as ow Anaeiohic SladgeBlanket) (sludge bed), fluidized bed and fixed bed are being developed.

[0003]

However, no matter which treatment method is used, a high-concentration organic suspension represented by, for example, shochu wastewater, beer yeast washing wastewater, rice washing wastewater, starch wastewater, etc. When the substance (SS) is contained, granules cannot be formed (UASB), the biofilm is detached (fluidized bed), the filter bed is closed (fixed bed), and the organic suspended substance (SS) is short-passed. It cannot be processed because the removal rate deteriorates.

[0004] In addition, when a completely mixed floating type bioreactor is used, the processing speed is slow, so a huge bioreactor is required. There was a problem that the amount of was very large.

Moreover, the organic suspended solids (SS) contained in these wastewaters account for 10 to 50% of the organic matter in the wastewaters, have very high viscosity, and can be concentrated and dewatered at low cost. Is difficult.

The present invention has been made to solve such a conventional problem, and an object thereof is to perform a solid-liquid separation of wastewater containing a high concentration of an organic suspended solid (SS). Separation into a supernatant liquid with a relatively low concentration of organic suspended solids (SS) and a concentrated liquid containing a high concentration of organic suspended solids (SS), which are separately subjected to anaerobic treatment. It is an object of the present invention to provide a method and an apparatus for anaerobic treatment of a high-concentration organic wastewater containing an organic suspended substance (SS), which has enabled the anaerobic treatment.

[0007]

According to the first aspect of the present invention, there is provided a method for anaerobic treatment of a high-concentration organic wastewater containing an organic suspended substance, wherein the wastewater containing a high concentration of the organic suspended substance is washed and solidified. After performing liquid separation, the supernatant liquid subjected to solid-liquid separation is supplied to an anaerobic bioreactor, treated by methane fermentation, and the organic suspended substance separated into solid and liquid is separated into a floating type having a membrane separation device. Is supplied to the anaerobic bioreactor and treated by methane fermentation.

According to a second aspect of the present invention, there is provided an anaerobic treatment method for high-concentration organic wastewater containing organic suspended substances, wherein the wastewater containing organic suspended substances at a high concentration is washed with treated water or diluted water. is there. The anaerobic treatment method of high-concentration organic wastewater containing an organic suspended substance according to claim 3 is the method according to claim 1, wherein the high-concentration organic wastewater containing the organic suspended substance is shochu wastewater, brewer's yeast washing. It is wastewater, rice washing wastewater, and starch wastewater.

According to a fourth aspect of the present invention, there is provided an anaerobic treatment method for a high-concentration organic wastewater containing an organic suspended substance, wherein the wastewater containing a high concentration of the organic suspended substance is washed, and
m or more organic suspended substances are removed.

The anaerobic treatment apparatus for high-concentration organic wastewater containing an organic suspended substance according to claim 5 comprises a raw solution tank for storing wastewater containing an organic suspended substance at a high concentration, and an organic suspension tank. A washing device for washing wastewater containing high concentrations of suspended solids, a solid-liquid separator, an anaerobic bioreactor that takes in the supernatant of the solid-liquid separator and processes it by methane fermentation, and a concentration of the solid-liquid separator Equipped with a suspended anaerobic bioreactor that takes in wastewater containing a high concentration of the suspended organic substances that have been treated and treated by methane fermentation, and a membrane separation device that is connected to the suspended anaerobic bioreactor. It is a thing.

The anaerobic treatment apparatus for high-concentration organic wastewater containing organic suspended substances according to claim 6 is the cleaning apparatus for cleaning wastewater containing organic suspended substances at high concentration according to claim 5. Is provided with a filtering member for removing organic suspended substances of 300 μm or more.

The anaerobic treatment apparatus for high-concentration organic wastewater containing an organic suspended substance according to claim 7 is characterized in that the anaerobic bioreactor of floating type and the membrane separation apparatus are connected to each other. , A circulation device is interposed.

[0013]

The organic suspended substance according to any one of claims 1 to 3 is represented by (S
In the anaerobic treatment method for the high-concentration organic wastewater containing S), the wastewater containing a high concentration of the organic suspended substance (SS) is washed, and the concentration of the organic suspended substance (SS) is relatively small. The supernatant is separated into a concentrated solution containing an organic suspension (SS) at a high concentration, and the supernatant having a relatively low concentration of the organic suspension (SS) is supplied to an anaerobic bioreactor. It is supplied and treated by methane fermentation, and a concentrated solution containing a high concentration of organic suspended solids (SS) is supplied to a floating type anaerobic bioreactor having a membrane separation device and treated by methane fermentation. .

According to a fourth aspect of the present invention, in the anaerobic treatment method for high-concentration organic wastewater containing organic suspended substances (SS), the wastewater containing organic suspended substances (SS) in high concentration is washed, For example, it is difficult to decompose such as potato skin, root, trunk, etc.
Remove organic suspensions (SS) greater than 0 μm.

In the anaerobic treatment apparatus for high-concentration organic wastewater containing organic suspended matter (SS) according to the fifth aspect, the organic suspended matter (SS) stored in the stock tank is contained in high concentration. The wastewater is washed with a washing device, and a supernatant liquid having a relatively low concentration of the organic suspended substance (SS) and a concentrated liquid containing a high concentration of the organic suspended substance (SS) are collected in the solid-liquid separation apparatus. And separated into
The supernatant liquid having a relatively low concentration of the organic suspended solid (SS) is treated by methane fermentation in an anaerobic bioreactor, and the concentrated liquid containing the organic suspended solid (SS) at a high concentration is removed. Methane fermentation in a floating type anaerobic bioreactor, and membrane separation by a membrane separator.

In the anaerobic treatment apparatus for high-concentration organic wastewater containing organic suspended matter (SS) according to claim 6,
An organic suspended substance (SS) of 0 μm or more is removed by a filtering member.

In the anaerobic treatment apparatus for high-concentration organic wastewater containing an organic suspended substance (SS) according to claim 7, the concentrated liquid containing the organic suspended substance (SS) at a high concentration is suspended. A anaerobic bioreactor is used for methane fermentation, and a membrane separator is used to perform membrane separation.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of an anaerobic treatment apparatus for high-concentration organic wastewater containing an organic suspended substance according to the present invention, wherein 1 is a stock solution tank.

In this stock solution tank 1, wastewater containing high-concentration organic suspended substances (SS) represented by, for example, shochu wastewater, beer yeast washing wastewater, rice washing wastewater, and starch wastewater is stored. You. This stock solution tank 1 communicates with a cleaning device 3 via a pipe 2.

The cleaning device 3 has, for example, a diameter of 0.5 mm.
A filtering member 4 for removing a large organic suspended substance (SS) of 300 μm or more, such as a punching plate, a filter, a screen, etc. having a large number of small holes. In addition, the washing device 3 includes an organic suspended substance (S
In order to sufficiently separate S) from wastewater, well water or circulating water is provided. The well water or circulating water required for that depends on the properties of the wastewater, but is about 100 times from undiluted. The setting of the dilution ratio is determined by the viscosity of the wastewater, and is set to 10 cP or less. The washing device 3 is in communication with a solid-liquid separation device 6 including an SS concentration tank via a pipe 5.

As the solid-liquid separation device 6, a precipitation basin or a centrifugal separator is used. In this solid-liquid separation device 6, an organic suspended solid (SS) having a relatively large particle diameter with a sedimentation velocity of 1 m / hour or more moves to the concentrate 6a side, and the supernatant 6b Only a light organic suspended solid (SS) with a sedimentation velocity of 1 m / hour or less is obtained. At this time, the concentration of the organic suspended substance (SS) in the concentrate is controlled to 50,000 mg / l or less. The solid-liquid separation device 6 communicates with a supernatant storage tank 8 via a pipe 7 and with a floating bioreactor 10 via a pipe 9.

The supernatant liquid storage tank 8 is connected to an anaerobic bioreactor 12 via a pipe 11. The anaerobic bioreactor 12 has a UASB that allows a high load.
(Upflow Anaeiohic Sladge Blanket) (sludge bed) type reactor, fluidized bed reactor, or fixed bed fluidized bed reactor is used. In this example, a fluidized bed reactor is shown. Further, the anaerobic bioreactor 12 is configured such that the supernatant liquid circulates through the pipe 13. In this circulation line, it is necessary to install a settling tank and control the concentration of the organic suspended solids (SS) in the circulating liquid to be 3,000 mg / l or less.

The anaerobic bioreactor 12 has a UASB (Upflow Anaei) depending on the concentration of the supernatant CODcr at the time of no dilution.
Any one of an ohic Sladge Blanket (sludge bed) type reactor, a fluidized bed type reactor, and a fixed bed fluidized bed type reactor is used.

By the way, the supernatant CODcr concentration was 6,000 m
In the case of g / l or less, UASB is used, and the circulation ratio of the reactor is 0 to 10. When the supernatant CODcr concentration is 6,
In the case of 000-15,000 mg / l, a fixed bed is used and the reactor circulation ratio is 10-20. Supernatant CODcr
When the concentration is 15,000 mg / l, a fixed bed is used and the circulation ratio of the reactor is 20-100.

Here, part or all of the generated circulating liquid is used as circulating water for cleaning the cleaning device 3. The concentration of the organic suspension (SS) at the time of dilution is 1,000 mg / l
It is desirable to control the following.

In the UASB, the upward flow velocity is 1 m /
Even if the organic suspended solids (SS) cannot be decomposed by setting the time more than an hour, the organic suspended solids (SS) will be
Is controlled to extrude out of the system so as not to affect the reaction. In the case of other reactors, the upward flow rate is greater than 1 m / h, so that organic suspended solids (SS) have little effect.

The BOD load can be expected to be 5 kg-BOD / m ³ / day or more, and the BOD efficiency can be expected to be 85%. Further, a biofilm separation tank 15 is connected to the anaerobic bioreactor 12 via a pipe 14 and a gas holder 17 is connected via a pipe 16. In addition, the biofilm separation tank 15
Are provided with pipes 18 and 19 for taking out treated water and excess sludge. Further, the gas holder 17 is provided with a pipe 20 for extracting methane gas.

On the other hand, the floating bioreactor 10 includes:
A circulating water tank 22 is connected via a pipe 21. A cross-flow type membrane separation device 24 using an ultrafiltration membrane or a microfiltration membrane is connected to the circulating water tank 22 via pipes 23 and 25. The membrane separation device 24 is provided with a pipe 28 for taking out the separated treated water. In addition, a return path to the floating bioreactor 10 is connected to the circulating water tank 22 via pipes 26 and 29. Furthermore, in the floating type bioreactor 10,
Sludge is drawn through the pipes 27 and 29. Further, the floating bioreactor 10 is provided with a pipe 3
The generated gas is sent to the gas holder 17 via the “0”. In this suspension type bioreactor 10, since the decomposition of the organic suspended solid (SS) is slow, the BOD load is set at about 1 to 5 kg / m ³ / day. In the floating bioreactor 10, the sludge is drawn out, so that the sludge concentration in the floating bioreactor 10 is 30,000 mg / l.
Control is performed as follows. Further, a part or all of the sludge circulating liquid used for cleaning the membrane surface at a membrane surface flow rate of 0.2 m / sec or more is used for stirring and mixing of the floating bioreactor 10. When mixing by the circulating liquid alone is insufficient, air lift stirring by the gas generated from the floating bioreactor 10 is also used. Usually, this operation removes the BOD by 95%.
The above can be expected.

Next, the organic suspension substance (SS) of the present invention
An anaerobic treatment method for high-concentration organic wastewater containing is described with reference to FIG. First, wastewater containing a high concentration of an organic suspended substance in a stock solution tank 1 is sent to a washing tank 3 via a pipe 2. Here, the organic suspended matter (SS) is sufficiently washed with the well water or the circulating water, so that the organic suspended matter (SS) and the liquid can be sufficiently separated.
And, for example, an organic suspended substance (SS) of 300 μm or more that is difficult to be decomposed, such as potato skin, root, stem, etc.,
It is removed by the filtering member 3. The viscosity of the filtrate is 10
The processing is performed so as to be equal to or less than cP.

Next, the filtrate is sent to a solid-liquid separator 6 via a pipe 5. Here, an organic suspended solid (SS) having a sedimentation velocity of 1 m / hour or more and a relatively large particle size is used as a concentrate 6
The suspension moves to the side a, and only the organic suspended substance (SS) having a relatively small particle diameter and a sedimentation speed of 1 m / hour or less is left on the supernatant 6b side. At this time, the concentration of the organic suspended substance (SS) in the concentrate 6a is controlled to 50,000 mg / l or less.

As described above, the high-concentration organic wastewater containing the organic suspended matter (SS) is different from the supernatant 6b containing little organic suspended matter (SS) and the high-concentration organic wastewater. It is separated into a concentrate 6a containing a suspended substance (SS).

Next, the supernatant 6b and the concentrate 6a are separately processed. First, the processing of the supernatant 6b will be described. The supernatant 6b having a low concentration of the organic suspended solids (SS) is subjected to BOD loading of 5 kg-BOD / m using a high-efficiency anaerobic bioreactor 12 such as a fluidized bed reactor.
Processed at a high load of ³ / day or more.

The supernatant 6b flowing out of the solid-liquid separator 6
Is stored in a supernatant liquid storage tank 8 via a pipe 7 and a pipe 11
To the high-efficiency anaerobic bioreactor 12. At this time, as the high-efficiency anaerobic bioreactor 12, three types of bioreactors are prepared according to the CODcr concentration of the supernatant 6b at the time of no dilution. That is, UASB when the CODcr concentration of the undiluted supernatant 6b is 6,000 mg / l or less, and UASB when the CODcr concentration is 6,000 to 15,000 mg / l or less,
In the case of a fixed bed and 15,000 mg / l or more, a fluidized bed is used.

In the high efficiency anaerobic bioreactor 12,
Since the supernatant 6b has a low concentration of the organic suspended solids (SS), the decomposition rate of the organic substances is dramatically improved, and only 9
A BOD removal rate of 0% or more is achieved, resulting in a large amount of methane gas. The generated methane gas is stored in a gas holder 17 via a pipe 16.

Next, the processing of the concentrate 6a will be described. Concentrate 6 containing high concentrations of organic suspended solids (SS)
a is a membrane separation device 24 having an ultrafiltration membrane or a microfiltration membrane.
The treatment is performed in the floating type bioreactor 10 combined with the above.

The concentrated solution 6a containing a high concentration of an organic suspended substance (SS) is sent to a floating bioreactor 10 via a pipe 9 communicating with the concentrated solution 6a side of the solid-liquid separation device 6. In the floating-type bioreactor 10, the BOD load is 1 to 5 kg-BOD while being stirred by the stirring action of the sludge circulating liquid and the stirring action of the air lift by the generated gas.
/ M ³ / day at a relatively high load. Then, the sludge in the floating-type bioreactor 10 is drawn out, and the sludge concentration is controlled to be 30,000 mg / l or less. At the same time, the circulating water tank 22 allows the floating bioreactor 1
The sludge within 0 is subjected to membrane separation processing by the membrane separation device 24.

As described above, since the supernatant 6b and the concentrated solution 6a are separately processed, the organic suspended substance (S
There are advantages such as that the residence time of S) can be kept extremely long, oxygen and bacteria can be kept at a high concentration, and the quality of treated water is good and stable. As a result, the treatment can be performed with a relatively high load of about 2 kg-BOD / m ³ / day, and the generation of excess sludge can be extremely reduced. The sludge generated is relatively easily concentrated and
Since it can be dewatered, energy and chemical costs for sludge treatment can be reduced.

Next, a case where the present invention is applied to a corn shochu waste liquid will be described. First, about the supernatant, C
Corn shochu waste liquid with an ODcr concentration of 18,000 mg / l
When processed using a flow-type bioreactor, BO
A D load of 13.5 kg-BOD / m ³ / day and a BOD removal rate of 85% or more were obtained. Further, 90% or more of CODcr could be recovered as methane.

Next, regarding the concentrated liquid, in the corn shochu waste liquid, 20,000 mg / l of an organic suspended substance (SS) of 9% was used.
0% or more was decomposable, and the removal rate of CODcr was 90% or more. Further, 90% or more of the removed CODcr could be recovered as methane.

2 and 3 are prepared based on this experiment. FIG. 2 shows the sludge conversion rate in the methane fermentation treatment of the corn shochu waste liquid, and FIG. 3 shows the COD removal in the methane fermentation treatment of the corn shochu waste liquid. Indicates the rate.

[0041]

As described above, according to the method and the apparatus for anaerobic treatment of high-concentration organic wastewater containing an organic suspended substance according to the present invention, a high-concentration organic suspended substance (S
In the anaerobic treatment of high-concentration organic wastewater containing S),
Organic suspended solids (SS) depending on dilution or treated water
Is thoroughly washed, solid-liquid separated, and an organic suspended substance (S
S) Separation into a supernatant having a relatively low concentration and a concentrate containing a high concentration of an organic suspended substance (SS), and the supernatant was subjected to UAS
B. High-speed anaerobic bioreactor such as solid bed and fluidized bed is used for high-speed processing, and the concentrated liquid is processed using a combination of a floating bioreactor and a membrane separation device. The decomposition rate of (SS) is dramatically improved, and a BOD removal rate of 90% or more is achieved only by anaerobic treatment, and as a result, a large amount of methane gas is obtained. The generated methane gas can be used as an energy source. The average load on the anaerobic bioreactor for treating the supernatant and the high-efficiency floating-type bioreactor for treating the concentrated solution is BOD load 3.3 kg-BOD
Since a high load of at least / m ³ / day can be achieved, the installation area of the device can be reduced, and the construction cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of an anaerobic treatment apparatus for high-concentration organic wastewater containing an organic suspended substance according to the present invention.

FIG. 2 is a graph showing a sludge conversion rate in a methane fermentation treatment of a corn shochu waste liquid.

FIG. 3 is a graph showing a COD removal rate in a methane fermentation treatment of a corn shochu waste liquid.

[Explanation of symbols]

 Reference Signs List 1 stock solution tank 3 washing device 6 solid-liquid separation device 10 floating bioreactor 12 anaerobic bioreactor 23 circulating water tank 24 membrane separation device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-5294 (JP, A) JP-A-4-110097 (JP, A) JP-A-4-131197 (JP, A) JP-A 62-294 279897 (JP, A) JP-A-64-70195 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 3/28, 11/04

Claims (7)

(57) [Claims] 1. A wastewater containing a high concentration of an organic suspended substance is washed, a solid-liquid separation is performed, and a supernatant liquid obtained by the solid-liquid separation is removed.
The suspension is supplied to an anaerobic bioreactor, treated by methane fermentation, and the solid suspended solids and liquids are supplied to a floating anaerobic bioreactor having a membrane separator to be treated by methane fermentation. An anaerobic treatment method for high-concentration organic wastewater containing an organic suspended substance, characterized by comprising: 2. The high-concentration organic wastewater containing an organic suspended substance according to claim 1, wherein the wastewater containing an organic suspended substance at a high concentration is washed with treated water or dilution water. Anaerobic treatment method. 3. The organic wastewater according to claim 1, wherein the high-concentration organic wastewater containing organic suspended substances is shochu wastewater, beer yeast washing wastewater, rice washing wastewater, and starch wastewater. Anaerobic treatment of high-concentration organic wastewater containing suspended substances. 4. The organic suspended matter according to claim 1, wherein the wastewater containing the organic suspended matter at a high concentration is washed to remove the organic suspended matter of 300 μm or more. Anaerobic treatment method for high-concentration organic wastewater containing. 5. A stock solution tank for storing wastewater containing organic suspended matter at a high concentration, a washing device for washing wastewater containing organic suspended matter at a high concentration, a solid-liquid separation device, An anaerobic bioreactor which takes in the supernatant of a liquid separation unit and treats it by methane fermentation, and takes in wastewater containing a high concentration of concentrated organic suspended solids in a solid-liquid separator and treats it by methane fermentation Floating anaerobic bioreactor and
An anaerobic treatment device for high-concentration organic wastewater containing organic suspended substances, comprising: a membrane separation device connected to a floating type anaerobic bioreactor. 6. The cleaning device according to claim 5, wherein the cleaning device for cleaning wastewater containing a high concentration of an organic suspended substance has a thickness of 300 μm.
An anaerobic treatment device for high-concentration organic wastewater containing organic suspended matter, comprising a filter member for removing the organic suspended matter described above. 7. The organic suspension according to claim 5, wherein a circulation device is interposed between the floating anaerobic bioreactor and the membrane separation device. Anaerobic treatment equipment for high-concentration organic wastewater.