JP2003170141A - Method and apparatus for treating organic waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating organic waste by which the production of a biologically hardly decomposable organic material such as a color component in a methane fermentation is suppressed to lower the load on a biological treatment and a biological denitrification is carried out by obtaining an organic carbon source in the system and to provide apparatus therefor. <P>SOLUTION: The organic waste is methane-fermented in a methane fermentation process 33, the methane fermentation sludge is dehydrated and separated in a solid liquid separation process 34 and the dehydration filtrate is biologically denitrificated in the biological denitrification process 35. The previously divided prescribed quantity of the organic waste is directly supplied to the biological denitrification process 35 without passing through the methane fermentation process 33. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and equipment for treating organic waste, and relates to a technology for removing nitrogen and bio-degradable substances contained in organic waste and its separated liquid.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, in the treatment of organic waste such as raw garbage and livestock excrement, the input raw material 1 is introduced to a pretreatment step 2 to remove fermentation inappropriate substances. Liquefaction (slurry or paste) with a crusher, etc., and lead the entire amount of this liquefaction to the methane fermentation step 3 to methane ferment in a mesophilic temperature range such as a membrane methane fermentation tank to reduce and produce It was recovering methane gas. Further, the methane fermentation sludge discharged from the methane fermentation process 3 is guided to a solid-liquid separation process 4 and dehydrated and separated by a dehydrator, the solid matter is composted, and the separated liquid is guided to a biological denitrification treatment process 5 to perform membrane separation. It was denitrified in a biological treatment tank equipped with a device, and biologically denitrified water was discharged in the advanced treatment step 6 after advanced treatment with ozone or activated carbon.

[0003]

In the methane fermentation step 3 described above, the organic carbon compounds are decomposed and gasified, but the nitrogen content is not removed, so the separated liquid of the methane fermentation sludge is generally excessive in nitrogen, BOD / N ratio becomes low. Therefore, when the separated liquid is subjected to a biological denitrification treatment, an organic carbon source such as methanol must be added from the outside of the system in order to supplement an organic substance serving as a hydrogen donor for denitrification. Also,
In the methane fermentation step 3, sugars and nitrogen compounds react with each other, and COD, chromaticity, etc. tend to increase. Therefore, the load of bio-hardly decomposable components in the subsequent biological denitrification step 5 and advanced treatment step 6 Will increase. In addition, methane fermentation sludge generally has a poor solid-liquid separation property, and the solid recovery rate in the solid-liquid separation step 4 is low.

The present invention is intended to solve the above-mentioned problems, and suppresses the expression of bio-hardly-degradable organic substances such as chromaticity in the methane fermentation process to reduce the load on biological treatment, and to use an organic carbon source as a system. It is an object of the present invention to provide a method and equipment for treating organic waste that can be obtained and biologically denitrified.

[0005]

In order to solve the above-mentioned problems, the method for treating organic waste of the present invention according to claim 1 is a method of methane-fermenting an organic waste in a methane fermentation step,
This methane fermentation sludge is dehydrated and separated in a solid-liquid separation step, and this dehydrated filtrate is biologically denitrified in a biological denitrification processing step. A predetermined amount of organic waste is divided in advance. It is directly supplied to the biological denitrification process without going through the methane fermentation process.

According to the above-mentioned constitution, the organic waste supplied to the system is guided to the biological denitrification process through the methane fermentation process, and the biological denitrification process without the methane fermentation process. It is possible to reduce the amount of treatment in the methane fermentation process and suppress the amount of biodegradable components such as chromaticity generated in the treatment process by dividing into By supplying the product to the biological denitrification process, the organic carbon source necessary for the biological denitrification process of the dehydrated filtrate of the methane fermentation sludge having a low BOD / N ratio can be covered by the organic substances in the system. .

In the method for treating organic waste of the present invention according to claim 2, the organic waste is subjected to methane fermentation in a methane fermentation step, and the methane fermentation sludge is dehydrated and separated in a solid-liquid separation step, and the dehydrated filter is A biological denitrification process for a liquid in a biological denitrification process, in which a predetermined amount of organic waste that has been divided in advance is directly supplied to the solid-liquid separation process without going through the methane fermentation process. Is.

With the above-mentioned constitution, the organic waste supplied to the system is led to the biological denitrification treatment step through the methane fermentation step, and the organic waste is fed to the solid-liquid separation step without passing through the methane fermentation step. By dividing the organic waste into solids, the amount of treatment in the methane fermentation process can be reduced and the amount of bio-hardly-degradable components such as chromaticity generated in the treatment process can be suppressed. BO by supplying to the liquid separation process
It is possible to cover the organic carbon source necessary for the biological denitrification treatment of the dehydrated filtrate of methane fermentation sludge having a low D / N ratio with the organic matter in the system. Moreover, by removing SS of the divided organic waste in the solid-liquid separation step, it can be effectively used as an organic carbon source.

According to a third aspect of the present invention, there is provided an organic waste treatment facility for methane fermentation of pretreatment means for liquefying an organic waste as a raw material and organic liquid waste discharged from the pretreatment means. A methane fermentation means for performing a solid-liquid separation means for solid-liquid separation of the fermentation sludge discharged from the methane fermentation means, and a biological denitrification treatment for biologically denitrifying the dehydrated filtrate dehydrated and separated by the solid-liquid separation means And a bypass line for branching the liquid feed line for feeding the organic liquid waste from the pretreatment unit to the methane fermentation unit to feed the organic liquid waste to the biological denitrification treatment unit. It is a thing.

According to a fourth aspect of the present invention, there is provided a facility for treating organic waste, comprising: a first valve provided in a liquid feed line for supplying the organic liquid waste from the pretreatment means to the methane fermentation means;
A second valve provided in a bypass pipe branching from a liquid feed pipe upstream of the valve to supply the organic liquid waste to the biological denitrification treatment means, and a water quality meter for measuring the water quality of the dehydrated filtrate. Then, based on the water quality value measured by the water quality meter, the opening amount of the first valve and the second valve is adjusted, and the divided amount of the organic liquid waste to be supplied to the biological denitrification treatment means through the bypass pipeline is calculated. And an automatic control device for controlling.

According to a fifth aspect of the present invention, there is provided a facility for treating organic waste, comprising a pretreatment means for liquefying an organic waste as a raw material for input, and a methane fermentation of the organic liquid waste discharged from the pretreatment means. A methane fermentation means for performing a solid-liquid separation means for solid-liquid separation of the fermentation sludge discharged from the methane fermentation means, and a biological denitrification treatment for biologically denitrifying the dehydrated filtrate dehydrated and separated by the solid-liquid separation means And a bypass line for branching the liquid feed line for feeding the organic liquid waste from the pretreatment unit to the methane fermentation unit to feed the organic liquid waste to the solid-liquid separation unit. .

According to a sixth aspect of the present invention, there is provided a facility for treating organic waste, comprising: a first valve provided in a liquid feed line for supplying the organic liquid waste from the pretreatment means to the methane fermentation means;
A second valve provided in a bypass pipe branching from the liquid supply pipe upstream of the valve to supply the organic liquid waste to the solid-liquid separation means, a water quality meter for measuring the water quality of the dehydrated filtrate, and a water quality An automatic control device for adjusting the opening amount of the first valve and the second valve based on the water quality value measured by the meter to control the divided amount of the organic liquid waste supplied to the solid-liquid separation means via the bypass pipe line; It is equipped with.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a treatment facility using organic waste such as raw garbage and livestock excrement as a raw material 31 has a pretreatment step 32 in which pretreatment means is a crusher or the like.
The methane fermentation step comprises an acid fermentation tank and a membrane-type methane fermentation tank having a membrane separation device provided in the tank, and the like, and a solid-liquid separation step in which the solid-liquid separation means includes a dehydrator. Biological denitrification process step 35 in which the denitrification treatment means is a multi-stage arrangement of denitrification tank, nitrification tank, denitrification tank, and nitrification tank provided with a membrane separation device, and advanced treatment means is an ozone treatment tank or an activated carbon treatment tank. And the advanced processing step 36.

The pretreatment step 32, the methane fermentation step 33, the solid-liquid separation step 34, the biological denitrification treatment step 35, and the advanced treatment step 36 are connected by a liquid feed conduit 37,
A first valve 38 is arranged in a liquid feeding conduit 37 for supplying an organic liquid waste from the pretreatment process 32 to the methane fermentation process 33. The bypass pipe 39 branches upstream from the first valve 38 from the liquid feeding pipe 37 to supply the organic liquid waste to the biological denitrification treatment step 35.
Has 0.

A water quality meter 41 for measuring the water quality of the dehydrated filtrate is provided in a liquid feed pipe 37 for supplying the dehydrated filtrate from the solid-liquid separation step 34 to the biological denitrification treatment step 35, and an automatic controller is provided. 42 is the first based on the water quality value measured by the water quality meter 41
The opening amounts of the valve 38 and the second valve 40 are adjusted to control the divided amount of the organic liquid waste supplied to the biological denitrification treatment step 35 via the bypass pipe 39.

The operation of the above structure will be described below. The input raw material 31 consisting of organic waste such as raw garbage and livestock excrement is guided to a pretreatment step 32 to remove unsuitable materials for fermentation and liquefied (slurried or pasted) by a crusher or the like. The liquefied organic liquid waste of the input raw material 31 is supplied to the methane fermentation process 33 through the liquid feeding conduit 37, and a predetermined amount of the organic liquid waste is divided and biologically removed through the bypass conduit 39. Supply to the nitrogen treatment step 35. The opening ratio of the first valve 38 and the second valve 40 is adjusted depending on the ratio of the amount of the organic liquid waste supplied to the methane fermentation process 33 and the amount of the organic liquid waste supplied to the biological denitrification treatment process 35. And control.

In the methane fermentation step 33, methane fermentation is carried out in a medium temperature range or a high temperature range in a membrane type methane fermentation tank or the like. The methane fermentation sludge discharged from the methane fermentation process 33 is led to a solid separation process 34, a polymer flocculant is added and dehydrated and separated by a dehydrator, and the dehydrated solid matter is sent to a composting process (not shown) to be composted. , Dehydration filtrate biological denitrification treatment step 3
Lead to 5.

In the biological denitrification treatment step 35, the dehydrated filtrate is biologically denitrified in the denitrification tank, the nitrification tank, the denitrification tank, and the nitrification tank arranged in multiple stages. The dewatered filtrate of methane fermentation sludge has a low BOD / N ratio for biological denitrification, and thus lacks an organic carbon source. Therefore, bypass line 39
The organic liquid waste that is supplied to the first denitrification tank through is used as an organic carbon source. The amount of the organic liquid waste supplied is such that the BOD / N ratio in the first denitrification tank of the biological denitrification treatment step 35 is about 3 times.

For this reason, the automatic controller 42 uses the water quality meter 41.
The water quality value (ammonia concentration) measured in step 2 is constantly monitored, and the first valve 38 and the second valve 4 are monitored based on the water quality value.
The opening degree of 0 is adjusted to control the division amount of the organic liquid waste supplied to the biological denitrification treatment step 35 via the bypass conduit 39, and the BOD / N of the dehydrated filtrate is judged from the water quality value. When the ratio is lower than the set value, the opening amount of the second valve 40 is increased to increase the divided amount of the organic liquid waste supplied to the biological denitrification treatment step 35 via the bypass line 39, The BOD / N ratio in the first denitrification tank of the biological denitrification treatment step 35 is maintained at an appropriate value.

In this way, the input raw material 31 supplied to the system
Through a methane fermentation step 33 and a biological denitrification step 3
The COD produced in the methane fermentation step 33 is reduced by dividing the methane fermentation step 33 into the biological denitrification treatment step 35 and the biological denitrification treatment step 35 without the methane fermentation step 33. In addition, the amount of biodegradable components such as chromaticity can be suppressed, and the biological denitrification treated water becomes treated water with lower chromaticity. By supplying the divided organic waste to the biological denitrification treatment step 35, the organic carbon source necessary for the biological denitrification treatment of the dehydrated filtrate of the methane fermentation sludge having a low BOD / N ratio is introduced in the system. Can be covered by organic matter.

Biological denitrification treated water is processed by the advanced treatment process 36.
It is discharged after advanced treatment with ozone or activated carbon.
In this advanced treatment step 36, the biological denitrification treated water is treated water having a low chromaticity, so that the load is reduced and the ozone injection rate and the activated carbon consumption can be reduced.

FIG. 2 shows another embodiment of the present invention, in which components having the same functions as those of the previous embodiment are designated by the same reference numerals and the description thereof will be omitted. In FIG.
The bypass line 39 is connected to the solid-liquid separation process 34.

In this structure, the organic liquid waste supplied through the bypass line 39 is solid-liquid separated together with the methane fermentation sludge in the solid-liquid separation step 34, and the dehydrated filtrate is sent to the biological denitrification processing step 35. Inflow. Therefore, the separated organic liquid waste flows into the biological denitrification treatment step 35 after SS is removed in the solid-liquid separation step 34, and is effectively used as an organic carbon source. In this case, since the dehydrated filtrate has already added the organic carbon source, its BOD / N ratio is about 3 times.

For this reason, the automatic controller 42 uses the water quality meter 41.
The water quality value (ammonia concentration) measured in step 2 is constantly monitored, and the first valve 38 and the second valve 4 are monitored based on the water quality value.
The opening amount of 0 is adjusted to control the division amount of the organic liquid waste supplied to the solid-liquid separation step 34 via the bypass pipe 39,
When the BOD / N ratio of the dehydrated filtrate is lower than the set value (about 3 times) as judged from the water quality value, the opening degree of the second valve 40 is increased to pass through the bypass pipe 39 and the solid-liquid separation step 34. Increase the divided amount of organic liquid waste supplied to
B in the first denitrification tank of the biological denitrification treatment step 35
Maintain the OD / N ratio at a proper value.

[0025]

As described above, according to the present invention, by dividing a predetermined amount of the input raw material to be fed into the system and guiding it to the biological denitrification process without passing through the methane fermentation process, The organic carbon source necessary for biological denitrification treatment of dehydrated filtrate of methane fermentation sludge with low BOD / N ratio is controlled in the system by suppressing the amount of bio-hardly-degradable components such as chromaticity generated in the fermentation process. Can be covered by organic matter. By removing SS of the divided organic waste in the solid-liquid separation step, it can be effectively used as an organic carbon source.

[Brief description of drawings]

FIG. 1 is a flow sheet showing an organic waste treatment facility according to an embodiment of the present invention.

FIG. 2 is a flow sheet showing a facility for treating organic waste according to another embodiment of the present invention.

FIG. 3 is a flow sheet showing a conventional organic waste treatment facility.

[Explanation of symbols]

31 Input material 32 Pretreatment process 33 Methane fermentation process 34 Solid-liquid separation process 35 Biological denitrification process 36 Advanced treatment process 37 Liquid transfer line 38 First valve 39 Bypass line 40 Second valve 41 Water quality meter 42 Automatic control device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiyuki Shibata             2-47 Shikitsuhigashi, Naniwa-ku, Osaka-shi, Osaka               Kubota Corporation (72) Inventor Toshihiro Komatsu             2-47 Shikitsuhigashi, Naniwa-ku, Osaka-shi, Osaka               Kubota Corporation (72) Inventor Tomoko Fujita             2-47 Shikitsuhigashi, Naniwa-ku, Osaka-shi, Osaka               Kubota Corporation F-term (reference) 4D004 AA02 CA04 CA10 CA13 CA18                       CB04 DA02 DA06 DA10                 4D040 BB02 BB13 BB15 BB24 BB42                       BB52 BB82 BB91 BB93                 4D059 AA07 BA12 BA32 BE01 CA21                       CA23 DA43 DA61 EA20 EB06                       EB11

Claims (6)

[Claims] 1. An organic waste is subjected to methane fermentation in a methane fermentation step, the methane fermentation sludge is dehydrated and separated in a solid-liquid separation step, and the dehydrated filtrate is biologically denitrified in a biological denitrification step. What is claimed is: 1. A method for treating an organic waste, which comprises directly supplying a predetermined amount of a divided organic waste directly to a biological denitrification treatment step without passing through a methane fermentation step. 2. An organic waste is subjected to methane fermentation in a methane fermentation step, the methane fermentation sludge is dehydrated and separated in a solid-liquid separation step, and the dehydrated filtrate is biologically denitrified in a biological denitrification step. A method for treating organic waste, which comprises treating a predetermined amount of the organic waste that has been divided in advance and directly supplying it to a solid-liquid separation step without passing through a methane fermentation step. 3. A pretreatment means for liquefying organic waste, a methane fermentation means for methane fermenting the organic liquid waste discharged from the pretreatment means, and a solid-liquid separation of fermented sludge discharged from the methane fermentation means. Solid-liquid separation means, a biological denitrification treatment means for biologically denitrifying the dehydrated filtrate dehydrated and separated by the solid-liquid separation means, and an organic liquid waste from the pretreatment means to the methane fermentation means And a bypass line for supplying the organic liquid waste to the biological denitrification treatment means. 4. A first valve provided in a liquid feeding pipeline for supplying an organic liquid waste from the pretreatment means to the methane fermentation means,
A second valve provided in a bypass pipe branching from the liquid supply pipe upstream from the first valve to supply the organic liquid waste to the biological denitrification treatment means and the water quality of the dehydrated filtrate are measured. Water quality meter and division of organic liquid waste to be supplied to biological denitrification treatment means through bypass line by adjusting opening of first valve and second valve based on water quality value measured by water quality meter The organic waste treatment facility according to claim 3, further comprising an automatic control device for controlling the amount. 5. A pretreatment means for liquefying an organic waste as an input material, a methane fermentation means for methane fermenting the organic liquid waste discharged from the pretreatment means, and a fermentation sludge discharged from the methane fermentation means. Solid-liquid separation means for solid-liquid separation,
Biological denitrification processing means for biologically denitrifying the dehydrated filtrate that has been dehydrated and separated by the solid-liquid separation means, and branching from a liquid feeding pipeline for supplying organic liquid waste from the pretreatment means to the methane fermentation means And a bypass line for supplying the organic liquid waste to the solid-liquid separation means. 6. A first valve provided in a liquid feeding pipeline for supplying an organic liquid waste from the pretreatment means to the methane fermentation means,
A second valve provided in a bypass pipe branching from the liquid supply pipe upstream of the first valve to supply the organic liquid waste to the solid-liquid separation means, and a water quality meter for measuring the water quality of the dehydrated filtrate. ,
An automatic control device for adjusting the opening amount of the first valve and the second valve based on the water quality value measured by the water quality meter to control the division amount of the organic liquid waste supplied to the solid-liquid separation means through the bypass pipe line. The organic waste treatment facility according to claim 5, further comprising: