JPH11309438A - Waste treating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste treating method by which organic wastes of various properties can effectively and easily be treated and the recovery efficiency of valuables can be improved. SOLUTION: Biologically treated sludge is subjected to solid-liquid separation into sludge contents and liquid filtrate by a first solid-liquid separation means 1. The sludge contents, liquid organic waste from which residue has been removed by a second pretreatment means 2, and solid organic waste from which impurities have been removed by a third pretreatment means 3 are tempered into a mixture. Magnesium compounds, phosphate compounds, iron compounds, nickel compounds, and cobalt compounds are added to the mixture, and the resultant matter is subjected to methane fermentation treatment in a methane fermentation tank 6. The fermented matter is subjected to solid-liquid separation into sludge to be made compost and treated liquid filtrate by a second solid-liquid separation means 7. After the liquid filtrate and the treated liquid filtrate are subjected to ammonia striping treatment, they are subjected to biological treatment by aerobic microorganisms and subjected to high treatment such as flocculation and membrane treatment by a high treatment means 11 to obtain treated water. Excess sludge and sludge of the high treatment means 11 are returned to the first solid-liquid separation means 1 and retreated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a waste treatment method for subjecting organic waste containing organic matter to methane fermentation.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, for example, liquid organic waste having fluidity such as human waste, livestock wastewater, septic tank sludge, agricultural settlement wastewater, sewage sludge, and food processing sludge which have been separately treated. And solid organic waste, such as kitchen garbage, are treated in one system, and at the time of disposal, solid fuel, fertilizers, and valuable resources such as methane gas are collected. Are known.

In the waste treatment method shown in FIG. 3, a solid-liquid separation step 22 is performed after a pre-treatment in a first pre-treatment step 21 such as pulverization of liquid organic waste or separation and removal of impurities.
The solid-liquid separation into a sludge component and a filtrate is performed, and the sludge component is separately subjected to methane fermentation in a methane fermentation tank 24 together with solid organic waste from which pulverization or impurities have been removed in advance in a second pretreatment step 23. Then, after recovering methane gas as a valuable material in the methane fermentation treatment, the dewatering step 25 dehydrates and separates the sludge into a treated filtrate, and the sludge is composted into fertilizers and collected as a valuable material, and the treated filtrate is separated into a solid and a liquid. In step 22, a nitrification and denitrification treatment is performed in a nitrification and denitrification step 26 together with a filtrate collected by solid-liquid separation of liquid organic waste, and further an advanced treatment step 27
For coagulation with a coagulant and treated as treated water. Excess sludge and coagulated sludge generated by the nitrification and denitrification treatment and coagulation treatment are returned to pretreatment of liquid organic waste and solid-liquid separation to be treated again.

[0004]

However, liquid organic waste such as human waste, livestock wastewater, fishery processing wastewater, etc.
It separates the sludge for methane fermentation by solid-liquid separation, but the filtrate has high BOD (Biochemical Oxyg
en Demand: biochemical oxygen demand) and a large amount of nitrogen compounds dissolved.
For this reason, it is necessary to perform a nitrification denitrification treatment which requires a complicated and large-sized apparatus for treating both the BOD and the nitrogen compound and requires a large energy for the treatment.
In addition, there is a problem that BOD and nitrogen compounds in the filtrate cannot be recovered as valuables.

[0005] In view of the above problems, the present invention can efficiently and easily treat various types of organic wastes,
An object of the present invention is to provide a waste disposal method that can improve the efficiency of collecting valuable resources.

[0006]

According to a first aspect of the present invention, there is provided a waste treatment method comprising the steps of solid-liquid separation of biologically treated sludge generated by biological treatment into a sludge component and a filtrate, and decomposing the sludge component and an anaerobic organism. The liquid organic waste with fluidity containing possible organic matter and the solid organic waste containing solid organic matter that can be decomposed by anaerobic organisms are stirred and mixed, and solidified after methane fermentation treatment. The treated filtrate is separated by liquid separation, and the treated filtrate is subjected to biological treatment with the filtrate by an aerobic microorganism.

[0007] The biologically treated sludge generated by the biological treatment is separated by solid-liquid separation into a sludge containing most of the total organic matter, and a liquid having a fluidity containing an organic matter decomposable by anaerobic organisms. The methane fermentation treatment is carried out by mixing and mixing liquefied organic waste in which a large amount of organic matter is present in part with solid organic waste containing solid organic matter that can be decomposed by anaerobic organisms. After the treatment, the treated filtrate separated and separated by solid-liquid separation and the filtrate separated and separated from the biologically treated sludge are subjected to biological treatment with aerobic microorganisms. Methane gas can be recovered as valuable resources, and the load of biological treatment by aerobic microorganisms in the post-process is reduced, resulting in downsizing of the device and reduction in operating energy.
It can be processed efficiently.

According to a second aspect of the present invention, there is provided a waste treatment method according to the first aspect, wherein excess sludge generated by biological treatment with an aerobic microorganism comprises sludge, liquid organic waste and solid organic waste. It is subjected to methane fermentation together with municipal waste.

[0009] The excess sludge generated by the biological treatment with the aerobic microorganisms is subjected to methane fermentation together with the sludge, liquid organic waste and solid organic waste to be collected as valuable methane gas. Since the methane fermentation treatment is surely performed and the methane gas is recovered as a valuable material, the treatment can be performed efficiently.

A waste treatment method according to a third aspect of the present invention is the waste treatment method according to the first or second aspect, wherein the total solid concentration is adjusted to a water content of 5% or more and 20% or less before the methane fermentation treatment. is there.

Since the water content is adjusted so that the total solid concentration becomes 5% or more and 20% or less before the methane fermentation treatment, an appropriate concentration for the methane fermentation treatment is obtained, and the methane fermentation treatment efficiency is improved. If the total solid concentration is lower than 5%, the concentration of the organic matter to be subjected to the methane fermentation treatment is reduced, and the amount of methane gas generated with respect to the operation energy is reduced, so that the efficiency of the methane fermentation is reduced. In addition, the total solid concentration is 20%
If it is higher, the viscosity increases and the presence of solid organic matter makes it impossible to uniformly decompose the organic matter in a short time, thereby lowering the efficiency of methane fermentation. Therefore, the total solid concentration is set to 5% or more and 20% or less before the methane fermentation treatment.

According to a fourth aspect of the present invention, there is provided the waste disposal method according to any one of the first to third aspects.
Prior to the methane fermentation treatment, impurities are removed from at least one of the liquid organic waste and the solid organic waste.

In order to remove impurities from at least one of the liquid organic waste and the solid organic waste before the methane fermentation treatment, the methane fermentation treatment is prevented from being hindered by the impurities. Efficiency is improved.

According to a fifth aspect of the present invention, there is provided a waste disposal method as set forth in any one of the first to fourth aspects.
A magnesium compound and a phosphate compound are added before or during the methane fermentation treatment.

Since the magnesium compound and the phosphate compound are added before or during the methane fermentation treatment, the nitrogen compounds remaining in the sludge of the biologically treated sludge and the nitrogen present in the liquid organic waste are removed. Since the compound reacts with the magnesium compound and the phosphate compound to generate and precipitate magnesium ammonium phosphate, the inhibition of the methane fermentation treatment by the nitrogen compound is prevented, and the methane fermentation treatment efficiency is improved.

According to a sixth aspect of the present invention, in the waste treatment method of the fifth aspect, when adding the magnesium compound and the phosphate compound, at least one of the iron compound, the cobalt compound and the nickel compound is added. It is to be added.

When adding the magnesium compound and the phosphate compound, at least one of the iron compound, the cobalt compound and the nickel compound is added. Even in such a state, the increased amount of the inactive effect of the iron, cobalt and nickel components of the nutrients is replenished, whereby the nutrient balance is secured and the methane fermentation treatment efficiency is improved.

According to a seventh aspect of the present invention, in the waste treatment method according to the fifth or sixth aspect, the amount of the magnesium compound and the phosphate compound is such that the concentration of the nitrogen compound in the methane fermentation treatment is 4000 ppm or less. It is the quantity which becomes.

The magnesium compound and the phosphate compound have a nitrogen compound concentration of 40 at the time of the methane fermentation treatment.
Since the addition is performed so as to be not more than 00 ppm, inhibition of the methane fermentation treatment by the nitrogen compound is reliably prevented, and the methane fermentation treatment efficiency is improved.

[0020] The waste disposal method according to claim 8 is the waste disposal method according to any one of claims 1 to 7,
It is to remove nitrogen compounds before biological treatment of the treated filtrate and the filtrate.

Further, since the treated filtrate and the filtrate are subjected to biological treatment to remove nitrogen compounds, the nitrogen compound is not required to be decomposed by nitrification and denitrification treatment, so that the apparatus configuration can be simplified and the treatment energy can be reduced. At the same time, the load of biological treatment is reduced, and the treatment efficiency is improved.

According to a ninth aspect of the present invention, in the waste disposal method of the eighth aspect, the nitrogen compound is removed by ammonia stripping.

In order to remove nitrogen compounds by ammonia stripping treatment before biological treatment, a filtrate obtained by solid-liquid separation of biologically treated sludge generated by biological treatment and containing relatively few organic substances and a large amount of nitrogen compounds, and In the treated filtrate with relatively little organic matter and many nitrogen compounds after methane fermentation, even in the state where nitrogen compounds can not be processed without additional organic matter in nitrification denitrification treatment,
Nitrogen compounds can be removed with a simple configuration and can be recovered as valuables. In addition, the load of biological treatment by aerobic microorganisms is reduced, and treatment efficiency is improved.

According to a tenth aspect of the present invention, there is provided the waste treatment method according to the eighth or ninth aspect, wherein the removal of the nitrogen compound comprises the step of removing the biologically treated oxygen from the treated filtrate and the mixture of the filtrate during the biological treatment. The removal is performed until the required amount (BOD) concentration becomes 15 times or more of the total nitrogen compound concentration.

Then, biological treatment is carried out to remove nitrogen compounds until the biochemical oxygen demand (BOD) concentration during the treatment filtrate and the mixture of the filtrate during the biological treatment becomes 15 times or more the total nitrogen compound concentration. Nitrogen compounds serving as a nutrient source to be ingested by the aerobic microorganisms are secured, the treatment efficiency is improved, and the nitrogen compounds remain at a high level without remaining.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a waste disposal method according to the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 denotes a first solid-liquid separation means, which is composed of surplus sludge and septic tank sludge separately generated by biological treatment with aerobic microorganisms or nitrification and denitrification treatment. , Sewage sludge, livestock wastewater sludge, agricultural settlement sludge, biologically processed sludge generated by the action of microorganisms such as food processing sludge, and dewatered into sludge and filtrate to solid-liquid separation, for example, a screw press Such a dehydrator is used.

On the other hand, reference numeral 2 denotes a first pre-processing means.
Is provided with, for example, a drum screen,
From liquid organic waste with fluidity such as human waste, livestock wastewater, agricultural settlement wastewater, sewage, and food processing wastewater to waste such as paper and cloth, textiles, and other impurities such as metal chips, glass, and plastic. Remove.

Reference numeral 3 denotes a second pre-processing means.
The pre-treatment means 3 is a solution (not shown) for breaking or crushing solid organic waste mainly containing solid organic matter such as business garbage such as garbage, kitchen waste, agricultural and marine waste, and food processing waste. A crushing device, a metal removing means (not shown) for magnetically sorting the crushed material crushed by the crushing device to remove impurities such as metal pieces, and a synthetic resin material contained in solid organic waste. A separation device (not shown) for removing impurities such as bags and plastics is provided.

The first solid-liquid separation means 1, the first pre-treatment means 2 and the second pre-treatment means 3 are provided with solid-liquid separated sludge and liquid organic waste from which impurities are removed. An adjusting tank 4 is connected as an adjusting means into which solid organic waste from which impurities are removed is input. The biologically treated sludge that has already been dehydrated, for example, dewatered sewage sludge, may be directly charged into the adjustment tank 4 without passing through the first solid-liquid separation means 1.

The adjusting tank 4 is provided with a stirring means (not shown) for stirring and mixing the introduced sludge, the liquid organic waste and the solid organic waste, and a means for heating to, for example, about 55-60 ° C. And a water adjusting means for adjusting the water content by appropriately adding water, and an adding means for adding a magnesium compound, a phosphoric acid compound, an iron compound, a cobalt compound and a nickel compound.

It is preferable to use steam when adding water and heating. By using steam,
There is no need to add water and separately heat with heating means, so that heating and water supply can be performed efficiently.

As the magnesium compound added by the adding means 5, for example, a magnesium salt, magnesium hydroxide, magnesium oxide or the like that dissociates magnesium ions is used. As the phosphate compound, for example, phosphate, which dissociates phosphate ions, Phosphoric acid, polycondensed phosphoric acid and the like are used. Further, iron compounds, cobalt compounds, and nickel compounds also use, for example, chlorides that dissociate as iron ions, cobalt ions, and nickel ions.

In the adjusting tank 4, a mixture prepared by mixing and stirring the sludge, the liquid organic waste and the solid organic waste while heating them to form a slurry in which lumps are mixed is also heated. A methane fermentation tank 6 as methane fermentation treatment means for performing methane fermentation treatment is connected. This methane fermenter 6
It is a biological suspension type that can process even concentrated slurry-like refining materials containing solid or massive organic waste, etc.
For example, an organic substance in the organic waste is subjected to methane fermentation treatment with anaerobic microorganisms such as methane-producing bacteria by appropriately stirring at 55 ° C to 60 ° C. The methane fermenter 6 is provided with methane gas collecting means (not shown) for collecting the generated methane gas. The methane gas recovery means is connected to a gas tank for storing the recovered methane gas. In addition, the recovered methane gas is used for heating of power generation and processing, and surplus energy can be supplied outside the facility.

The methane fermentation tank 6 further dehydrates the processed product obtained by methane fermentation of the mixture into treated filtrate and sludge to separate solid and liquid. For example, a centrifugal dehydrator, a rotating disk dehydrator, Second solid-liquid separation means 7 using a dehydrator such as a screw press is connected. The sludge separated by the second solid-liquid separation means 7 is transported to a composting step where the sludge is separately processed into fertilizer or the like.
The second solid-liquid separation means 7 may be provided with a coagulation means for adding a polymer coagulant to coagulate remaining contaminants.

The first solid-liquid separating means 1 and the second solid-liquid separating means 7 have the filtrate collected by the first solid-liquid separating means 1 and the second solid-liquid separating means 7, respectively. The nitrogen compound removing means 8 into which the treated filtrate is charged is connected. The nitrogen compound removing means 8 includes an ammonia stripping processing means for removing nitrogen compounds such as ammoniacal nitrogen (NH ₃ -N) by ammonia stripping the fed filtrate and the treated filtrate. That is, the ammonia stripping treatment means puts the filtrate and the treatment filtrate into an aeration tank provided with an aeration means (not shown), aerated and dissolved in the filtrate and the treatment filtrate such as ammonia nitrogen (NH ₃ -N). Stripping by air exposure to transfer nitrogen compounds into the air, and allowing the air containing the nitrogen compounds to permeate into an acidic aqueous solution that is an inorganic acid aqueous solution such as sulfuric acid or hydrochloric acid stored in an acidic tank, and The compound is precipitated and recovered, for example, as ammonium sulfate or ammonium chloride.

The ammonia stripping treatment means of the nitrogen compound removing means 8 is connected to an aerobic biological treatment means 9 for biologically treating the filtrate subjected to the ammonia stripping treatment and the treated filtrate with an aerobic microorganism. The aerobic biological treatment means 9 is provided with an aeration means (not shown) for aeration of the supplied filtrate after the ammonia stripping treatment and air for supplying oxygen to the treated filtrate. The aerobic biological treatment means 9 is provided with a third solid-liquid separation means (not shown) for solid-liquid separation of excess sludge, and the excess sludge collected by the third solid-liquid separation means is subjected to the first solid-liquid separation means. An excess sludge return means 10 for returning to the solid-liquid separation means 1 is connected.

Further, the filtrate treated biologically by the aerobic microorganism and the treated filtrate are added to the aerobic biological treatment means 9.
For example, the contaminants dissolved by the addition of a coagulant are aggregated and solid-liquid separated, the contaminants are separated by adsorption with activated carbon, etc., and the contaminants are removed by advanced membrane separation such as ultrafiltration or reverse osmosis membrane. An advanced processing means 11 for performing advanced processing is connected, and the filtrate and the processed filtrate are subjected to advanced processing by the advanced processing means 11 and discharged as a processing liquid.
The advanced treatment means 11 is connected to a sludge return means 12 for returning collected coagulated sludge or membrane separated sludge separated by membrane separation to the first solid-liquid separation means 1. In the case of advanced treatment with activated carbon, no sludge return means is provided.

Next, the operation of the above embodiment will be described.

First, the biologically treated sludge is dehydrated by a first solid-liquid separation means 1 into a filtrate and a sludge portion to be separated into a solid and a liquid.

Further, foreign substances are removed from the liquid organic waste by the first pretreatment means 2.

Further, the solid organic waste is broken or crushed by the second pretreatment means 3 to remove impurities such as synthetic resin bags and plastics, and is further subjected to magnetic separation to produce metal pieces and the like. Remove impurities.

Then, the sludge content from the first solid-liquid separation means 1, the liquid organic waste pretreated by the first pretreatment means 2, and the pretreatment by the second pretreatment means 3 The solid organic waste thus obtained is charged into the adjusting tank 4. In the adjusting tank 4, the mixture is stirred and mixed while being heated to about 55 ° C. using, for example, steam, and the total solids concentration (TS), which is the concentration of all evaporation residues that can be stirred and mixed, is 5% or more. Condition a slurry-like mixture in which lumps of 20% or less are mixed. If the TS concentration is higher than 20%, the stirring and mixing at the time of the methane fermentation treatment become insufficient and the methane fermentation treatment in the subsequent step cannot be performed efficiently.
Or less, preferably 18% or less. Further, when the TS concentration is lower than 5%, the water content is increased and the proportion of organic substances is reduced, and the efficiency of the methane fermentation treatment in the subsequent step is reduced. Therefore, the TS concentration is 5% or more, preferably 7.5.
Set to more than%. Also, by making the slurry in a state where there is little or almost no lump,
The methane fermentation treatment by microorganisms proceeds more efficiently.

At the time of tempering in the adjusting tank 4, the mixture TS
The concentration is measured, and the TS concentration is 5% or more, preferably 7.5.
% Or more, the addition means 5 adds at least one of iron compounds, nickel compounds and cobalt compounds as nutrients. These nutrients are
10 mg / l or more, preferably 10-300 mg / l as iron, 1 mg / l or more, preferably 1-30 mg / l as nickel and 1 mg / l or more, preferably 1-30 mg / l as cobalt are added to the mixture. .

When the TS concentration is lower than 5%, trace effects of iron, nickel and cobalt contained in the organic waste are reduced due to agglomeration, sedimentation, scale formation and the like, and anaerobic. Since a sufficient amount of nutrients necessary for the activity of the microorganism can be obtained, it is not necessary to separately add nutrients.

On the other hand, if the amount of iron added is less than 10 mg / l, no improvement in the methane fermentation treatment in the subsequent stage is observed, and if it is more than 300 mg / l, no difference in the effect due to the addition of iron is observed and the cost increases. Therefore, the amount of iron added is 10 mg / liter or more, preferably 10 to 300 mg.
Per liter of an iron compound. Similarly, when the amount of nickel added is less than 1 mg / liter, no improvement in the methane fermentation treatment in the subsequent stage is observed, and
Even if the amount is more than mg / liter, no difference in effect due to the addition of nickel is recognized and the cost increases. Therefore, the nickel compound is added so that the amount of nickel added is 1 mg / liter or more, preferably 1 to 30 mg / liter. Similarly, if the amount of cobalt added is less than 1 mg / liter, no improvement in the methane fermentation treatment in the subsequent stage is observed, and if it exceeds 30 mg / liter, no difference in the effect of the cobalt addition is observed and the cost increases. Therefore, the addition amount of cobalt is 1 mg / liter or more, preferably 1 to 3
A cobalt compound is added so as to be 0 mg / liter.

Further, a magnesium compound such as magnesium salt, magnesium hydroxide and magnesium oxide, and a phosphoric acid compound such as phosphate, phosphoric acid and polycondensed phosphoric acid are added by adding means 5. In addition, although ammonia nitrogen (NH ₃ -N) is already present in the adjusting tank 4, acid fermentation of the organic waste of each property is progressing in the adjusting tank 4, and the pH becomes about 5. Therefore, the addition of a magnesium compound and a phosphoric acid compound causes the compound to react with ammonium nitrogen (NH ₃ —N), which is a nitrogen compound in the mixture, to react with magnesium ammonium phosphate (Mg (NH ₄ ) PO).
₄ ) is not generated suddenly and adheres to the wall surface of the adjustment tank 4 as a scale.

The amounts of addition of the magnesium compound and the phosphate compound are such that the nitrogen compound is reduced to an amount that does not affect the methane fermentation in the subsequent methane fermentation treatment. That is, the methane fermentation treatment is 55 ° C to 60 ° C.
In high temperature fermentation, the ammonia nitrogen concentration is 2500pp
m, preferably 2000 ppm or less, 35 ° C to 40 ° C
4,000 ppm or less, preferably 3 ppm
The addition amount is set so as to reduce to 000 ppm or less.

Here, all of the ammoniacal nitrogen (NH ₃ —N), which is a nitrogen compound in the mixture, can be produced as magnesium ammonium phosphate (Mg (NH ₄ ) PO ₄ ). Since ammonium ammonium phosphate having a molecular weight ratio of 10 times the ammonia nitrogen concentration is generated, for example, if 4000 ppm of ammonia nitrogen is present in the mixture, 40,000 ppm of magnesium ammonium phosphate is generated, and this 40,000 ppm of magnesium phosphate is produced. Ammonium is equivalent to 4% in TS concentration, and as described above, there is a possibility that the TS concentration may be out of the appropriate range of 5% or more and 20% or less, so it is necessary to pay attention to moisture adjustment.

The magnesium compound is added so that the molar ratio of magnesium is 1 or less with respect to the total phosphoric acid concentration, which is the total amount of the phosphate compound to be added and the phosphate ions in the mixture. The generation of scale due to precipitation of a magnesium compound in a subsequent step is prevented.

Further, phosphate ions are a nutrient source for aerobic microorganisms in the subsequent aerobic biological treatment, but the removal operation is not easy.
The addition amount of the magnesium compound and the phosphoric acid compound is set so as to be at most 10 ppm, preferably at most 10 ppm.

Then, a nutrient salt such as an iron compound, a nickel compound and a cobalt compound is appropriately added, and a mixture prepared by adding a magnesium compound and a phosphoric acid compound is allowed to flow into the methane fermentation tank 6.
The mixture is allowed to stay for 8 days while being appropriately stirred, and the organic matter is subjected to methane fermentation treatment with methanogens or the like. The methane gas generated by the methane fermentation treatment is collected by a methane gas collection means (not shown) and stored in a gas tank, which is used for the operation energy for the treatment of the organic waste such as power generation, other sewage treatment, and cooling and heating. Use.

Since the methane fermenter 6 is in a stable state in an alkaline atmosphere having a pH of 7 or more, ammonia nitrogen (NH ₃ −), which is a nitrogen compound in the mixture flowing into the methane fermenter 6. N) reacts with the magnesium compound and the phosphoric acid compound added in advance in the adjusting tank 4 to react with magnesium ammonium phosphate (Mg (NH
₄₎ to generate the PO _4).

[0054] Iron, nickel and cobalt are substances constituting coenzyme components of microorganisms such as methanogens and are nutrient elements indispensable for improving the activity of microorganisms. In addition, iron is about 1000 mg / liter, nickel is about 80-240.
mg / liter and cobalt is about 50-150 mg /
On the other hand, when the amount becomes more than 1 liter, the activity of the microorganism starts to be inhibited.

In the methane fermentation tank 6, a slurry-like mixture containing a solid organic waste and having a high concentration is treated, so that physical and physical effects such as coagulation and precipitation, formation of scale fine particles, and coprecipitation adsorption effects are obtained. It is considered that a chemical reaction has occurred.

For this reason, when the TS concentration of the tempered material charged into the methane fermentation tank 6 which is the input TS concentration is lower than 5%, the concentration of the coagulation / precipitation and scale forming substances in the methane fermentation tank 6 is relatively low. The effect of micronutrients such as iron, nickel and cobalt due to physicochemical reactions such as coagulation / sedimentation and scale formation is relatively low, and anaerobic microorganisms such as methane-producing bacteria It absorbs active iron, nickel, and cobalt as nutrients to increase the activity and efficiently decompose organic substances. In addition,
In this case, in a biological suspension type methane fermentation treatment method capable of treating solid organic waste, BOD (Biochemica
l Oxygen Demand: biochemical oxygen demand)
At 50,000 ppm, the residence time is about 8 days and the treatment is almost the upper limit load (4 to 6 kg / m ³ · day in BOD load), that is, anaerobic microorganisms feed active iron, nickel and cobalt in the refining material. This is the upper limit of processing conditions under which organic matter can be decomposed by absorption as a source.

On the other hand, when the TS concentration is 5% or more, especially 7.5%
As a result, the inactive effect of iron, nickel, and cobalt increases due to precipitation and scale formation, the activity decreases due to the lack of iron, nickel, and cobalt required by anaerobic microorganisms, and the above-mentioned processable TOC is reduced. (Total Organic Carbo
n: Total organic carbon) load and chemical oxygen demand (CO
Even under the conditions of the processing load at which the D _Cr ) load and the BOD load are equal or lower, the methane fermentation efficiency is greatly reduced or stopped.

Therefore, as described above, in the above-described embodiment, methane fermentation treatment is performed when solid organic waste containing solid organic matter such as garbage, kitchen waste, and agricultural and marine waste is subjected to methane fermentation. When the TS concentration at the time of charging into the tank 6 is 5
% Or more, at least one of the iron compound, the nickel compound and the cobalt compound has an iron concentration of 1
0-300mg / liter, nickel concentration 1-30mg /
Liter and cobalt concentration to be 1 to 30 mg / liter.

Next, the fermentation product subjected to the methane fermentation treatment is solid-liquid separated by a second solid-liquid separation means 7 into a dewatered cake as sludge and a separated water as a treated filtrate. And the separated liquid is
The filtrate collected by the solid-liquid separation by the first solid-liquid separation means 1 is conveyed to the ammonia stripping treatment means of the nitrogen compound removing means 8 together with the filtrate, and the dehydrated cake is composted into fertilizer or the like and incinerated. Note that the first preprocessing means 2
And since the contaminants are sufficiently removed by the second pretreatment means 3 and the dehydrated cake contains magnesium ammonium phosphate, it is composted and contains fertilizers containing inorganic nutrients of nitrogen, phosphorus and magnesium. That is, by adding a buffering fertilizing component, the compost is recovered as a valuable material such as fertilizer which has been added to the function of the compost as a soil conditioner.

At the time of the solid-liquid separation by the second solid-liquid separation means 7, in order to reduce the load of biological treatment in a subsequent step, a flocculant is added to the BOD by adding a flocculant to reduce the BOD in the treated filtrate. The resulting organic matter is agglomerated, then dehydrated and solid-liquid separated.
Here, the dewatered cake, which is solid-liquid separated sludge, is preferably dewatered by adding a polymer flocculant in order to reduce the water content for composting used as a fertilizer and for reducing the amount of heat for drying. Various cationic coagulants can be used as the polymer coagulant.
Amidine-based flocculants that can be reduced to 0 ppm or less are preferred.

The filtrate and the treated filtrate conveyed to the ammonia stripping treatment means of the nitrogen compound removing means 8 are aerated in an alkaline atmosphere by aeration means (not shown), and are nitrogen compounds dissolved in the filtrate and the treated filtrate. Perform stripping by aeration that transfers ammoniacal nitrogen into the aerated air. Here, as the alkali atmosphere, an alkali such as sodium hydroxide, potassium hydroxide, slaked lime or the like is added to the filtrate and the treated filtrate, and stripping is performed by adding alkali. Then, the air containing the nitrogen compound is permeated into an acidic aqueous solution which is an inorganic acid aqueous solution such as sulfuric acid or hydrochloric acid stored in an acid tank, and the nitrogen compound is precipitated and recovered as, for example, ammonium sulfate or ammonium chloride. . The removal of the nitrogen compound is performed so that the BOD / N is 15 or more.

On the other hand, the stripped filtrate and the treated filtrate flow into the aerobic biological treatment means 9 and are biologically treated by aerobic microorganisms, that is, oxidatively decompose remaining organic substances to reduce BOD. At the time of this biological treatment, nitrogen compounds and phosphate compounds remaining without being removed by the ammonia stripping treatment are ingested as nutrients of aerobic microorganisms, and the BOD is reduced and the remaining trace amounts of nitrogen compounds and phosphate compounds are reduced. The components are also reduced.

Further, the biologically treated filtrate and the treated filtrate are subjected to advanced treatment such as acidic coagulation sedimentation, sand filtration, activated carbon adsorption treatment and membrane treatment by the advanced treatment means 11 to obtain chromaticity, BOD concentration and COD concentration. To obtain good treated water with low phosphate compounds. In the case of the coagulation treatment, an inorganic coagulant such as a ferric chloride or a sulfate band may be used. Further, by using the membrane treatment after the aggregation treatment, stable treated water can be efficiently obtained. Then, sludge such as coagulated sludge and membrane separation sludge generated by the advanced treatment is returned to the first solid-liquid separation unit 1 via the sludge return unit 12 and processed again.

As described above, the biologically treated sludge produced by biological treatment of the waste and the liquid organic liquid containing a large amount of the organic substance in the liquid portion having a fluidity containing an organic substance decomposable by anaerobic organisms. Waste and solid organic waste containing solid organic matter that can be decomposed by anaerobic organisms.
The sludge fraction obtained by solid-liquid separation and separation of biologically treated sludge, which contains most of the organic matter in the entire waste, is separated into liquid waste, liquid organic waste, and solid organic waste. While being recovered as valuables, the organic matter in the entire waste is reduced and the remaining organic matter can be treated only by biological treatment with a simple aerobic microorganism,
The apparatus can be reduced in size and operating energy can be reduced, and the entire waste can be efficiently treated.

Further, surplus sludge generated by biological treatment by aerobic microorganisms and sludge generated by advanced treatment are returned to the first solid-liquid separation means 1 to be separated into solid and liquid, and the sludge, liquid organic waste and solid Since the methane fermentation treatment is performed together with the shaped organic waste and collected as valuable methane gas, the organic matter can be surely subjected to methane fermentation treatment and collected as valuable methane gas, thereby improving the treatment efficiency.

Since the biologically treated sludge is dehydrated and solid-liquid separated by the first solid-liquid separation means 1, the organic matter to be subjected to methane fermentation can be surely separated into solid and liquid on the sludge side, and the recovery efficiency as methane gas is improved. It is possible to reduce the load of the biological treatment in the post-process, and to improve the waste treatment efficiency.

Further, since the water content is adjusted so that the total solid concentration becomes 5% or more and 20% or less before the methane fermentation treatment, the concentration becomes suitable for the methane fermentation treatment, and the methane fermentation treatment efficiency can be improved.

In addition, prior to the methane fermentation treatment, a pretreatment for removing impurities from the liquid organic waste and the solid organic waste is performed in advance, so that the methane fermentation treatment can be prevented from being hindered by the impurities. Processing efficiency can be improved.

Further, before or during the methane fermentation treatment, a magnesium compound and a phosphate compound are added, and the nitrogen compound is reacted with the magnesium compound and the phosphate compound in the methane fermentation tank 6 in which the pH becomes alkaline, whereby phosphoric acid is added. Since it is produced and precipitated as magnesium ammonium, inhibition of the methane fermentation treatment by a nitrogen compound can be prevented, and methane fermentation treatment can be performed efficiently.

Further, the magnesium compound and the phosphate compound were replaced with a nitrogen compound having a concentration of 400 at the time of the methane fermentation treatment.
Since it is added so as to be 0 ppm or less, inhibition of the methane fermentation treatment by a nitrogen compound can be reliably prevented, and the methane fermentation treatment efficiency can be improved.

Since at least one of the iron compound, the cobalt compound and the nickel compound is added when adding the magnesium compound and the phosphate compound, the total solid concentration and the nitrogen compound concentration are increased during the methane fermentation treatment. Even in such a state, the increased amount of the inactive effect of the nutrients of iron, cobalt and nickel can be replenished, and the nutrient balance can be secured and methane fermentation can be performed efficiently.

Further, the filtrate collected by the solid-liquid separation of the biologically treated sludge and the treated filtrate collected by the solid-liquid separation after the methane fermentation treatment are used to remove nitrogen compounds before the biological treatment by the aerobic microorganisms. Decomposition treatment of nitrogen compounds by nitrification denitrification treatment is not required, so that the apparatus configuration can be simplified and treatment energy can be reduced, and the load of biological treatment can be reduced, thereby improving treatment efficiency.

Further, in order to remove the nitrogen compound, the ammonia stripping treatment is carried out with a simple structure, so that a filtrate obtained by solid-liquid separation of the biologically treated sludge generated by the biological treatment is relatively free from organic matter and contains a large amount of nitrogen compound, and In the treated filtrate with relatively little organic matter and many nitrogen compounds after methane fermentation, even in the state where nitrogen compounds can not be processed without additional organic matter in nitrification denitrification treatment,
The nitrogen compound can be removed with a simple configuration and can be recovered as a valuable resource, and the load of biological treatment by aerobic microorganisms can be reduced and the treatment efficiency can be improved. Then, ammonia stripping is performed between the filtrate from which the sludge has been removed from the biologically treated sludge and the treated filtrate that has been subjected to solid-liquid separation after the methane fermentation treatment. The nitrogen compound can be stably removed without preventing the ripping treatment.

The magnesium compound and the phosphate compound have a nitrogen compound concentration of 40 at the time of the methane fermentation treatment.
Since it is added so as to be not more than 00 ppm, inhibition of the methane fermentation treatment by the nitrogen compound can be reliably prevented, and the methane fermentation treatment efficiency can be improved.

Further, in order to remove nitrogen compounds until the concentration of organic substances in the treated filtrate and the mixture of the filtrates at the time of biological treatment becomes 15 times or more of the total nitrogen compound concentration, the nutrient source ingested by the aerobic microorganisms to be biologically treated. Nitrogen compound can be secured, the processing efficiency can be improved, and the nitrogen compound can be highly reduced without remaining.

In the above embodiment, the first solid-liquid separation means 1 and the second solid-liquid separation means 7 have been described as being solid-liquid separated by dehydration using a dehydrator. Solid-liquid separation may be performed, or solid-liquid separation may be performed by precipitation separation.

Further, biologically treated sludge, liquid organic waste,
Depending on the content of nitrogen compounds in various forms of solid organic waste and the residual amount of nitrogen compounds during biological treatment, nitrification and denitrification may be performed during biological treatment. Further, by using the nitrification and denitrification treatment having a simple structure, the structure of the preceding ammonia stripping treatment can be simplified.

Further, when the amount of the nitrogen compound contained is small, a step of removing the nitrogen compound such as an ammonia stripping treatment may not be provided. In addition, liquid organic waste such as septic tank sludge and livestock wastewater sludge covering all waste containing organic matter, liquid organic waste such as human waste and livestock wastewater, and various forms of solid organic waste are: Since a large amount of nitrogen compounds is contained, a treatment apparatus for treating waste is generally provided with a structure for removing nitrogen compounds. The removal of the nitrogen compound is not limited to the ammonia stripping treatment. Further, the ammonia stripping treatment is not limited to the submerged gas diffusion method, but may be, for example, a packed tower method using Raschig ring or the like. However, the liquid submerged gas diffusion method is preferable in consideration of clogging of the packed bed by SS.

In the second solid-liquid separation means 7, the coagulation / separation treatment is performed, but the coagulation / separation processing may not be performed by the solid-liquid separation method. By using the coagulation treatment together, solid-liquid separation can be performed in a short time with a simple structure.

On the other hand, the liquid organic waste and the solid organic waste are preliminarily treated to remove impurities, but the pretreatment may be omitted when the content of the impurities is small. .

In the above description, the magnesium compound and the phosphate compound are added before and during the methane fermentation treatment. However, when the amount of the nitrogen compound is small, the magnesium compound and the phosphate compound are added. You don't have to. In addition, liquid organic waste such as septic tank sludge and livestock wastewater sludge covering all waste containing organic matter, liquid organic waste such as human waste and livestock wastewater, and various forms of solid organic waste are: Since a large amount of nitrogen compounds is contained, a treatment apparatus for treating waste is generally provided with a configuration in which these magnesium compounds and phosphoric acid compounds are added.

In the above description, a nutrient of any one of an iron compound, a cobalt compound and a nickel compound is added. However, when the nature of the treatment does not increase the inactive effect, it may not be added. In addition, similarly, when processing waste in various forms such as biologically treated sludge, liquid organic waste, and solid organic waste covering the entire waste containing organic substances, the inert effect generally increases. To do
It is added to ensure nutritional balance.

[0083]

EXAMPLE A comparison was made on the difference in treatment efficiency depending on the type of waste to be treated.

[0084] The form of the waste is as follows: the remaining rice, such as vegetables, fruits, meat, fish, cooked rice, etc., is crushed into a slurry by mixing and stirring to obtain a water content of about 80% (TS concentration of about 20%). Prepare garbage as solid organic waste. Further, as the liquid organic waste, used was human waste collected from a human waste processing plant, which had been pre-treated to remove the waste by a 10-mm sieve. Furthermore, as biologically treated sludge, septic tank sludge collected from a human waste treatment plant was used, and ferric chloride was added to the wastewater treatment plant.
After adding 000 ppm and stirring and mixing, a cationic polymer flocculant is added to the TS concentration by 2% to perform a flocculation treatment, filtered through a coarse filter cloth and sufficiently squeezed to remove dewatered sludge as sludge. Solid-liquid separation was performed with the filtrate. Table 1 shows these properties. Table 2 shows the properties of the filtrate of the septic tank sludge.

[0085]

[Table 1]

[Table 2] As a treatment method, a method of dividing waste into three forms of biologically treated sludge, liquid organic waste, and solid organic waste by treating the waste of the embodiment shown in FIG. A method of separating waste into two forms, liquid organic wastewater and solid organic waste shown in FIG. 3 as an example, and mixing various forms of waste shown in FIG. 4 as a conventional example. Then, the method of treating the waste as one form of waste was evaluated by observing the treatment state.

First, the process of separating waste into the three forms shown in FIG. 1 will be described.

10 kg of the excrement removed from the above-mentioned pretreatment, 0.5 kg of dewatered sludge separated by solid-liquid separation of septic tank sludge (the amount of dewatered sludge obtained from 10 kg of septic tank sludge) and 5 kg of synthetic garbage are mixed by stirring. Temper the mixture. Table 3 shows the properties of the tempered mixture.

[0088]

[Table 3] Then, the tempered mixture was put into a methane fermentation tank that had already been acclimated, and subjected to methane fermentation at about 55 ° C.
The result is shown in FIG. At the beginning of the treatment, the residence time was 30 days.

From the results shown in FIG. 2, the ammonia concentration in the methane fermentation tank was as high as 3200 to 3800 mg / l, and the organic acid accumulated in a considerable amount of 4000 to 8000 mg / l. Although the pH and the methane production rate did not change due to the accumulation of the organic acid, the BOD concentration in the treated filtrate obtained by solid-liquid separation after the methane fermentation treatment increased, and the load of the biological treatment in the subsequent process increased. Needs to be reduced. Therefore, in order to increase the activity of the anaerobic microorganism methanogen, 500 mg / liter of iron as a nutrient element as ferric chloride, 50 mg / liter of nickel as nickel chloride, and 50 mg / liter as cobalt as cobalt chloride. One liter was added continuously. As a result, the organic acid concentration was reduced to about 1000 mg / liter.

When a large amount of organic acid was not recognized and the treatment state was stabilized, the residence time was set to 15 days. Due to the increase in the load of the methane fermentation treatment due to the shortening of the residence time, the organic acids started to accumulate again and increased to about 10,000 mg / liter.

It is considered that the increase in the load strongly affected the ammonia nitrogen (NH ₄ -N), and as a result, methane fermentation was inhibited.

In general, since ammonia inhibits methane fermentation, the operation is performed at an ammonia nitrogen concentration of about 2000 mg / liter. However, even if a trace element such as a nutrient element is added, the inhibition of methane fermentation by ammonia nitrogen can be prevented. It turns out that it cannot be prevented.

Then, a magnesium compound and a phosphoric acid compound were added, and the ammonia nitrogen concentration was increased to about 2000 mg /
When reduced to liters, the accumulation of organic acids was prevented and reduced to 300-560 mg / liter. In this state, even if the residence time was reduced to 7.5 days, the organic acid could not be accumulated and could be treated stably. Then, in this state, the methane content in the digested gas was about 59%, and the amount of digested gas generated was 0.35 liter / g · input COD _Cr , indicating that good results were obtained.

After that, when the addition of the trace element was stopped, the organic acid concentration gradually increased and the pH became acidic even when the ammonia nitrogen concentration was about 2,000 mg / liter, and it became rancid.

As described above, when the TS concentration and the ammonia nitrogen, which is a nitrogen compound, are high, the addition of a trace element can prevent a certain amount of organic acid from accumulating. The effect appears,
The accumulation of organic acids indicates that it is necessary to reduce the amount of ammonia nitrogen by adding a trace element and adding a magnesium compound and a phosphate compound in order to allow the methane fermentation treatment to proceed stably and efficiently.

On the other hand, when the residence time is 15 days and the organic acid concentration is 50
The mixture subjected to methane fermentation treatment in a stable state at about 0 mg / liter is subjected to a coagulation treatment using a polyamidine-based strong cationic polymer coagulant and a general polyacrylate ester-based strong cationic polymer coagulant, followed by dehydration. Solid-liquid separation was carried out into a dewatered cake as sludge and a treated filtrate. Table 4 shows the properties of the dehydrated cake and the treated filtrate, and Table 5 shows the results of component analysis in the dehydrated cake obtained by coagulation treatment with a polyamidine-based strong cationic polymer coagulant.

[0097]

[Table 4]

[Table 5] From the results shown in Table 4, the water content of the dehydrated cake of the polyacrylic acid ester-based strong cationic polymer coagulant was 82.
In contrast to 4%, the polyamidine-based strong cationic polymer flocculant was 77.8%, indicating a large difference.
Also, the BOD in the treated filtrate was 430 mg / liter for the polyamidine-based strong cationic polymer flocculant, and was 500 mg.
/ Liter or less. However, it can be seen that the total nitrogen concentration (TN) is as high as about 2200 mg / liter. In addition, from the results shown in Table 5, fertilizer components that produce an effect as a fertilizer with nitrogen (N) 7.2%, phosphorus (P) 12.1%, and magnesium (Mg) 5.3% per dry weight. It can be seen that many are included.

Then, the collected treated filtrate is subjected to an aerobic microorganism treatment together with the filtrate separated by solid-liquid separation of the septic tank sludge in advance. Here, the volume ratio between the treated filtrate and the filtrate is almost the same since the ratio between human waste and septic tank sludge is 1: 1. Therefore, from the results shown in Tables 2 and 4, the mixture of the filtrate and the treated filtrate had a BOD of about 70.
0mg / liter, total nitrogen concentration (TN) about 1300mg
By removing nitrogen compounds by ammonia stripping or the like, the biological treatment by aerobic microorganisms in the subsequent step has a BOD of about 700 mg / liter.
Activated sludge treatment with a low load of treating liters of sewage is required.

Next, equal amounts of the filtrate and the treated filtrate were mixed,
Ammonia stripping was performed. In this treatment method, first, sodium hydroxide is added to the filtrate and the treatment filtrate put in the pH adjustment tank to adjust the pH to 11, and then a 1-liter capacity tank flows into a stripping tank connected in two stages in series. Then, air was diffused from an air diffuser provided in each tank to perform an ammonia stripping treatment. Table 6 shows the results.

[0100]

[Table 6] From the results shown in Table 6, the ammonia nitrogen concentration was 14%.
It could be reduced from 60 mg / liter to 31 mg / liter. The properties shown in Table 7 were obtained by the ammonia stripping treatment.

[0101]

[Table 7] Thereafter, by the activated sludge method, which is a biological treatment with aerobic microorganisms, treated water shown in Table 8 in which BOD, SS, and total nitrogen were satisfactorily reduced was obtained.

[0102]

[Table 8] On the other hand, in Comparative Example 1 shown in FIG. 3, the synthetic garbage of the above-described example, waste in two forms in which human waste and septic tank sludge were mixed at a ratio of 1: 1 was used as a starting material, and a solid-liquid separation step 22 was performed. Liquid separation, that is, a cationic polymer flocculant is added to the mixed human waste and septic tank sludge at 2% with respect to the TS concentration, and the mixture is subjected to flocculation treatment.
The solid-liquid separation was carried out into dewatered sludge as kg of sludge and about 18.5 kg of filtrate. Table 9 shows the properties of the dewatered sludge and the filtrate.

[0103]

[Table 9] Here, BOD / N in the normal nitrification denitrification treatment is 3.5 to
When the filtrate shown in Table 9 is subjected to nitrification and denitrification in the subsequent nitrification and denitrification step 26, the BOD becomes insufficient, and an organic carbon source such as methanol is added. There is a need to. For this reason, the actual load at the time of the nitrification denitrification treatment is such that the BOD concentration is 6700 to 7680.
mg / l, total nitrogen concentration 1920 mg / l. Therefore, the sludge has a much larger load than the activated sludge treatment with a BOD concentration of 700 mg / liter in the three embodiments, which results in an increase in the size of the treatment apparatus and an increase in the consumption energy. According to the example, it is understood that the configuration of the biological treatment in the post-process can be simplified and the energy consumption can be reduced, and waste can be efficiently processed with a simple configuration.

Further, in order to perform methane fermentation treatment in the methane fermentation tank 24, 5 kg of synthetic garbage is added to 1.5 kg of dewatered sludge collected from a mixture of human waste and septic tank sludge, and water is added to reduce the TS concentration to 10%. %. Table 10 shows the properties.

[0105]

[Table 10] From the results shown in Tables 1 and 9, 10 kg of human waste and 10 liters of septic tank sludge at the time of introducing the reconditioned material obtained by conditioning the mixture of dehydrated sludge and synthetic garbage into the methane fermentation tank 24 into which the mixture flows.
When the amount of COD _Cr per kg and 5 kg of synthetic garbage is calculated by the following method, 1.5 [kg] × 180 [g / kg] +5 [kg] × 307 [g / kg] = 1
805 [g], and the comparative example 1 shown in FIG. 3 weighs about 1.8 kg.

On the other hand, the waste of the above embodiment was put into a methane fermentation tank into which a mixture of 10 kg of human waste in three forms, 0.5 kg of solid-liquid separated sludge of a septic tank sludge, and 5 kg of synthetic garbage was introduced. COD _Cr amount is 10 [kg] x 32 [g / kg] + 0.5 [kg] x 307 [g / kg] x 5
[kg] × 169 [g / kg] = 1940 [g], which is about 2.0 kg. Further, since the methane recovery rate in methane fermentation is substantially determined by the amount of COD _Cr to be input, the methane recovery rate in the treatment method according to Comparative Example 1 shown in FIG. That is, it can be seen that the treatment as in the present embodiment can improve the methane recovery rate by 10% compared to the conventional method.

Next, in Comparative Example 2 shown in FIG. 4, the synthetic garbage, human waste and septic tank sludge of the above embodiment were mixed.
The waste city of the form is treated as a starting material.
That is, the liquid organic waste and the solid organic waste of the conventional example which is Comparative Example 1 shown in FIG. 3 are subjected to a pretreatment such as pulverization or separation and removal of impurities in a pretreatment step 31 at a time. After that, in a solid-liquid separation step 32, solid-liquid separation is performed into sludge and a filtrate, and the sludge is subjected to methane fermentation in a methane fermentation tank 33. Furthermore, after recovering methane gas as a valuable material in the methane fermentation treatment, the sludge and the treated filtrate are dehydrated and separated in a dehydration step 34, and the sludge is composted into fertilizers and collected as a valuable material, and the treated filtrate is subjected to a phosphate removal step. At step 35, magnesium ammonium phosphate is formed by the addition of a magnesium compound and a phosphate compound and separated, and the treated filtrate from which phosphoric acid has been removed is subjected to a nitrification and denitrification step together with the filtrate collected at the solid-liquid separation step 32.
A nitrification denitrification treatment is performed at 36, and a coagulation treatment is performed with a coagulant at an advanced treatment step 37, which is treated as treated water. Excess sludge generated by the nitrification and denitrification treatment is returned to pretreatment of liquid organic waste or solid-liquid separation for treatment again.

According to the treatment process of Comparative Example 2 shown in FIG. 4, 20 kg of a mixture of human waste and septic tank sludge 1: 1 was added.
5 kg of synthetic garbage is mixed and subjected to solid-liquid separation corresponding to the solid-liquid separation step 32, that is, coagulation treatment is performed by adding a cationic polymer coagulant to the TS concentration by 2%, and filtered through a coarse filter cloth. The mixture was sufficiently squeezed and solid-liquid separated into about 3.9 kg of dewatered sludge as sludge and about 21.1 kg of filtrate. Table 11 shows the properties of the dewatered sludge and the filtrate.

[0109]

[Table 11] Then, when the amount of COD _Cr supplied to the methane fermentation tank 33 is calculated in the same manner as described above, the amount is about 1.4 kg. In the treatment method according to Comparative Example 2 shown in FIG. It turns out that a recovery rate falls. Furthermore, comparing the BOD amount of the filtrate, Table 2 and Table 11 show that (21.1 [kg] × 12000 [mg / l]) / (9.5 [kg] ×
880 [mg / l]) = 30.3, which is about 30 times higher than that of the above example, and it can be seen that the load of biological treatment in the subsequent process increases.

Further, Comparative Example 1 shown in FIG. 3 and Comparative Example 2 shown in FIG. 4 were subjected to an ammonia stripping treatment in the same manner as in the above example. As a result, the foaming was so severe that the ammonia stripping treatment could not be continued.
This corresponds to Comparative Example 1 shown in FIG. 3 and Comparative Example 2 shown in FIG.
Then, it is considered that liquid waste that has not undergone biological treatment, such as liquid waste and garbage, is rich in protein and high-molecular organic matter. Therefore, an ammonia defoaming agent such as silicon was added to suppress foaming, and the ammonia stripping treatment was continued under the same conditions as in the example. Table 12 shows the results.
Shown in

[0111]

[Table 12] From the results shown in Table 12, it can be seen that the removal ratio of ammonia nitrogen is lower than that of the above-mentioned Example. This is considered to be because the defoaming agent silicon is prevented from gathering on the gas-liquid surface and ammonia nitrogen from being diffused from the liquid phase to the gas phase.

On the other hand, in order to prevent the adverse effects of these foams, it is conceivable to carry out ammonia stripping after reducing the BOD by biological treatment. However, aeration for supplying dissolved oxygen during biological treatment is considered. Ammonia nitrogen causes a nitrification reaction to generate nitric acid or nitrous acid, and cannot perform only oxidative decomposition of BOD. Since the generated nitric acid and nitrous acid cannot be removed by the ammonia stripping treatment, the total nitrogen concentration does not decrease so much even if the ammonia stripping treatment is performed after the biological treatment, resulting in a high nitrogen content. Therefore, FIGS. 3 and 4
In the comparative example shown in the above, the ammonia stripping process having a simple configuration cannot be used, and if the apparatus is large and complicated, and the nitrification denitrification process that consumes a large amount of processing energy is not performed,
Processed water having a total nitrogen concentration of 10 mg / liter or less, which is a standard for advanced treatment, cannot be obtained.

Therefore, in the above embodiment, if the total nitrogen concentration is reduced to about several tens of mg / liter, the total nitrogen concentration, which is a standard for advanced treatment of nitrogen compounds by the biological treatment in the subsequent step, is 10 mg / liter. Since it can be reduced to liters or less, it can be seen that the processing apparatus can be simplified and reduced in size and the consumption energy for processing can be reduced.

[0114]

According to the first aspect of the present invention, there is provided a waste treatment method comprising the steps of solid-liquid separation of biologically treated sludge and separation of the sludge where most of the total organic matter is present, and liquid where a large amount of organic matter is present in the liquid portion. Organic waste, solid organic waste containing solid organic matter is stirred and mixed and methane fermented,
After the methane fermentation treatment, the treated filtrate obtained by solid-liquid separation and separation and the filtrate obtained by solid-liquid separation and separation of biologically treated sludge are subjected to biological treatment by aerobic microorganisms. Methane fermentation treatment can be recovered as valuable methane gas, improving the recovery efficiency as methane gas, reducing the load of biological treatment by aerobic microorganisms in the post-process, simplifying and downsizing the equipment and reducing operating energy The waste can be treated efficiently.

According to the waste disposal method of the second aspect,
In addition to the effect of the waste treatment method according to claim 1, surplus sludge generated by biological treatment with aerobic microorganisms is subjected to methane fermentation together with sludge, liquid organic waste and solid organic waste to produce methane gas. Since the organic matter can be reliably collected by methane fermentation and collected as valuable methane gas, it can be more efficiently treated because it is recovered as a valuable resource.

According to the waste disposal method of the third aspect,
In addition to the effects of the waste disposal method according to claim 1 or 2,
5% or more 20% of total solids concentration before methane fermentation
Since the water content is adjusted to be as follows, an appropriate concentration for methane fermentation treatment is obtained, and the methane fermentation treatment efficiency can be improved.

According to the waste treatment method of the fourth aspect,
In addition to the effects of the waste treatment method according to any one of claims 1 to 3, in addition to removing impurities from at least one of a liquid organic waste and a solid organic waste before performing methane fermentation treatment, It is possible to prevent the methane fermentation treatment from being hindered by substances, improve the methane recovery rate with respect to the operating energy, and improve the methane fermentation treatment efficiency.

According to the waste disposal method of the fifth aspect,
In addition to the effects of the waste treatment method according to any one of claims 1 to 4, the magnesium compound and the phosphate compound are added before or during the methane fermentation treatment, so that they remain in the sludge of the biologically treated sludge. Nitrogen compounds,
Nitrogen compounds present in the liquid organic waste react with magnesium compounds and phosphate compounds to form and precipitate magnesium ammonium phosphate, preventing the inhibition of methane fermentation treatment by nitrogen compounds and improving methane fermentation treatment efficiency. it can.

According to the waste disposal method of the sixth aspect,
In addition to the effect of the waste treatment method according to claim 5, when adding a magnesium compound and a phosphoric acid compound, at least one of an iron compound, a cobalt compound and a nickel compound is added. Even in the state where the solid matter concentration and the nitrogen compound concentration are high, the increased amount of the inactive effect of the nutrients of iron, cobalt and nickel can be replenished, and the nutrient salt balance can be ensured to improve the methane fermentation treatment efficiency.

According to the waste disposal method of claim 7,
In addition to the effects of the waste disposal method according to claim 5 or 6,
Since the magnesium compound and the phosphate compound are added so that the concentration of the nitrogen compound during the methane fermentation treatment becomes 4000 ppm or less, the inhibition of the methane fermentation treatment by the nitrogen compound can be surely prevented, and the methane fermentation treatment efficiency can be improved.

According to the waste treatment method of the eighth aspect,
In addition to the effects of the waste treatment method according to any one of claims 1 to 7, nitrogen compounds are removed before biological treatment of the treated filtrate and the filtrate, so that nitrogen compound decomposing treatment by nitrification denitrification treatment becomes unnecessary. In addition, the size of the apparatus can be simplified and reduced, the processing energy can be reduced, the load of biological treatment can be reduced, and the processing efficiency can be improved.

According to the ninth aspect of the present invention,
In addition to the effect of the waste treatment method according to claim 8, since nitrogen compounds are removed by ammonia stripping treatment before biological treatment, relatively organic substances obtained by solid-liquid separation of biologically treated sludge generated by biological treatment are obtained. A filtrate with a small amount of nitrogen compounds and a filtrate with a relatively small amount of organic compounds after methane fermentation and a relatively large amount of nitrogen compounds.Even in a state where nitrogen compounds cannot be treated without additional organic matter in nitrification and denitrification, With such a configuration, the nitrogen compound can be removed and recovered as a valuable resource, the load of biological treatment by aerobic microorganisms can be reduced, and the treatment efficiency can be improved.

According to the waste treatment method of the tenth aspect, in addition to the effect of the waste treatment method of the eighth or ninth aspect, the treatment filtrate during the biological treatment and the biochemical oxygen demand during the mixing of the filtrate. Nitrogen compounds are removed until the amount (BOD) concentration becomes 15 times or more of the total nitrogen compound concentration, so that a nitrogen compound as a nutrient source ingested by the aerobic microorganisms to be biologically treated can be secured, and the treatment efficiency can be improved. Highly reduced without leaving nitrogen compounds.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a waste disposal method according to the present invention.

FIG. 2 is a graph showing the results of an experiment in which methane fermentation was performed using human waste, septic tank sludge, and synthetic garbage in the processing step shown in FIG.

FIG. 3 is a block diagram showing a configuration of a conventional waste disposal method.

FIG. 4 is a block diagram showing a configuration of another conventional waste disposal method.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 first solid-liquid separation means 2 first pretreatment means 3 second pretreatment means 6 methane fermentation tank as methane fermentation treatment means 7 second solid-liquid separation means 8 ammonia stripping as nitrogen compound removal means Treatment process 9 Biological treatment means 10 Excess sludge return means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Sasaki 2-9-1-9, Noribori, Nishi-ku, Osaka, Osaka Inside Ataka Industry Co., Ltd. (72) Kazuhiro Akamine 2-9-1, Noribori, Nishi-ku, Osaka, Osaka Ataca Industry Co., Ltd.

Claims (10)

[Claims] 1. A liquid organic waste having a fluidity, comprising a liquid-solid separation of a biologically treated sludge generated by a biological treatment into a sludge component and a filtrate, and the sludge component and an organic substance decomposable by anaerobic organisms. The mixture is stirred and mixed with a solid organic waste containing a solid organic substance that can be decomposed by an anaerobic organism, subjected to methane fermentation treatment, and then subjected to solid-liquid separation to collect a treatment filtrate. A waste treatment method, comprising biologically treating an aerobic microorganism with a filtrate. 2. The waste according to claim 1, wherein the excess sludge generated by the biological treatment with the aerobic microorganism is subjected to methane fermentation together with the sludge, liquid organic waste and solid organic waste. Processing method. 3. The waste treatment method according to claim 1, wherein the water content is adjusted to a total solid concentration of 5% or more and 20% or less before the methane fermentation treatment. 4. The waste disposal method according to claim 1, wherein impurities are removed from at least one of a liquid organic waste and a solid organic waste before the methane fermentation treatment. . 5. The waste treatment method according to claim 1, wherein a magnesium compound and a phosphate compound are added before or during the methane fermentation treatment. 6. The waste treatment method according to claim 5, wherein at least one of an iron compound, a cobalt compound and a nickel compound is added when adding the magnesium compound and the phosphate compound. 7. The addition amount of the magnesium compound and the phosphoric acid compound is determined when the concentration of the nitrogen compound in the methane fermentation treatment is 4%.
7. The method according to claim 5, wherein the amount is 000 ppm or less. 8. The process filtrate according to claim 1, wherein nitrogen compounds are removed before biological treatment of the filtrate.
The waste disposal method according to any one of the above. 9. The waste treatment method according to claim 8, wherein the removal of the nitrogen compound is performed by ammonia stripping. 10. The removal of nitrogen compounds is carried out until the concentration of biochemical oxygen demand (BOD) in the treated filtrate and the mixing of the filtrate during the biological treatment is at least 15 times the total nitrogen compound concentration. The waste disposal method according to claim 8 or 9, wherein