JPH10216785A - Treatment of night soil, garbage and sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method of night soil, garbage and sludge by which sludge of an organic waste water treatment facility, sludge such as private sewage treatment tank sludge, night soil and garbage containing animal and plants wastes are treated with reduced energy consumption, and night soil and insanitary screen residue in the private sewage treatment tank sludge are sanitarily converted to compost and solid fuel. SOLUTION: The treatment method of night soil, garbage and sludge consists of (a) a pretreatment process 2 for performing solid-liquid separation of night soil mixed with sludge, (b) an anaerobic digestion process 4 for directly anaerobically digesting solid matter separated in the pretreatment process without dewatering it, (c) the an anaerobic digestion process 4 for anaerobically digesting garbage containing animal and plants wastes and solid matter, (d) a dewatering process 20 for dewatering and separating outflowing liquid of the anaerobic digestion process into solid matter and separated water and (e) a biological treatment process for biologically oxidizing and denitrifying separation water of the pretreatment process 2 and separation water separated from the dewatering process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy-saving method for treating sludge from organic wastewater treatment facilities, sludge such as septic tank sludge, night soil, and kitchen waste containing animal and plant residues. The suggestion relates to a method for treating compost, solid waste, human waste, kitchen waste, and sludge in a hygienic manner.

[0002]

2. Description of the Related Art Anaerobic digestion of human waste has conventionally been widely used as an energy-saving treatment method. However, at present, denitrification and dephosphorization are being performed to prevent eutrophication of enclosed water bodies. Anaerobic digestion facilities have not been built at present because they degrade BOD substances in urine, which is not necessary for denitrification. Most of the septic tank sludge is treated in human waste treatment facilities together with human waste. Although some of the garbage in combustibles discharged as general waste is directly buried in final disposal sites, most of it is currently incinerated in garbage incinerators.

[0003]

The denitrification treatment of night soil treatment involves the power consumption of a blower related to the nitrification of nitrogen, a large amount of sludge generated in the treatment process, dehydration, drying and unsanitary suggestion generated in the pretreatment. Since the power cost such as the power consumption of the drive unit of the device related to incineration is large and occupies about half of the entire processing cost, reduction of the cost has been a pending issue in human waste treatment.

[0004] Human waste contains a large amount of foreign substances such as toilet paper, vinyl pieces, cloth pieces, and the like. In order to prevent clogging of the pump by such foreign substances in the human waste processing, a rotary screen is usually used in the pretreatment step. Removes these contaminants. Separated water content 10
The suggestion of about% is covered with human waste and is extremely unsanitary, so it is not effectively used and dehydrated by a screw press and then incinerated.

[0005] Septic tank sludge has a problem in terms of treatment due to a large fluctuation in SS concentration, and combined septic tank sludge with a large amount of oil causes troubles such as floating of sludge in a settling tank during water treatment.

[0006] Kitchen garbage in general waste causes a change in calorific value during incineration, and there is a concern that dioxin may be generated due to salts in the kitchen garbage. In some cases, kitchen waste is separated and collected for composting, but due to the burden of composting consumption and the problem of distribution of manufactured compost, it is not always smooth.

[0007] The anaerobic digestion treatment of kitchen garbage in general waste is
Although it has been experimentally studied as a promising technology, it has not been put to practical use until now because the equipment and operation costs for digestion / elimination liquid treatment are high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and solves the above-mentioned problems. Thus, sludge from an organic wastewater treatment facility, sludge such as a septic tank sludge, human waste, and kitchen waste containing animal and plant residues are energy-efficiently treated. In addition, an object of the present invention is to provide a method for treating human waste, kitchen waste, and sludge which is made into compost and solid fuel in a sanitary manner, indicating unsanitary suggestions in human waste and septic tank sludge.

[0009]

According to a first aspect of the present invention, there is provided a method for treating human waste, kitchen waste, and sludge, comprising the following steps (a) to (f). It is in. (A) a pretreatment step of solid-liquid separation of human waste mixed with sludge,
(B) an anaerobic digestion step of directly anaerobic digestion of solids separated in the treatment step without dehydration, (c) an anaerobic digestion step of anaerobic digestion of animal and plant residues and kitchen waste containing solids,
(D) a dewatering step of dewatering and separating the effluent from the anaerobic digestion step into solids and separated water, and (e) a biological treatment of biologically oxidizing and denitrifying the separated water from the pretreatment step and the separated water from the dehydration step. Process.

[0010] The invention described in claim 2 is the same as the claim 1.
In the method for treating human waste, kitchen waste, and sludge described in (1), the pretreatment step is characterized in that it is mixed with sludge and urine at the same time or is separated into solid and liquid at different time periods.

[0011] The invention according to claim 3 is based on claim 1.
In the method for treating night soil, kitchen waste, and sludge, the pretreatment step includes a sludge solid-liquid separation step for sludge and a night soil-liquid separation step for night soil.

The invention described in claim 4 is the first invention.
4. The method for treating night soil, kitchen waste, and sludge according to any one of the above-described items 3, wherein a coagulant is injected into the sludge in the treatment step.

The invention described in claim 5 is the first invention.
5. The method for treating night soil, kitchen waste, and sludge according to any one of Items 4 to 4, wherein the anaerobic digestion step includes an acid fermentation (solubilization) step and a methane fermentation step subsequent to the step.

[0014] The invention according to claim 6 is the first invention.
In the method for treating night soil, kitchen waste, and sludge according to any one of the above items 5, the solid content of the sludge discharged from the pretreatment step is adjusted to 12% or less.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to this embodiment. FIG. 1 is a diagram showing an example of a flow of a method for treating human waste, kitchen waste, and sludge according to the present invention. Night soil 1
In the pretreatment step 2 in which a solid-liquid separator such as a rotary screen is provided, coarse solids in the human waste 1 are removed, and the sieving residue (coarse solids) is anaerobically digested via the sieving residue / sludge pipe 3. Introduced to step 4.

The filtrate 14 from which impurities have been removed is stored in the storage tank 5.
Is introduced into the nitrification denitrification step 6 through which nitrogen is biologically treated. In the nitrification denitrification step 6, a conventional technique such as a circulating nitrification denitrification method can be used. The denitrification treatment water 7 is further introduced into an advanced treatment step 8 for treating COD, phosphorus, etc., as required, and the treated water 9 is discharged. In the advanced treatment step 8, conventional techniques such as coagulation sedimentation and activated carbon adsorption can be used.

The wastewater sludge 10 and the excess sludge 11 from the nitrification and denitrification step 6 are agglomerated by a polymer (organic polymer flocculant) 13 injected into a mixing tank 12, followed by a pretreatment step 2.
The separated sludge is introduced into the anaerobic digestion step 4 via the sieve residue / sludge pipe 3. The filtrate 14 is processed through the storage tank 5 in the same manner as in the case of urine filtration.

The anaerobic digestion step 4 can use a conventional methane fermentation technique such as a methane fermentation tank alone digestion or a two-phase digestion in which an acid fermentation tank and a methane fermentation tank are connected.

The solid-liquid separation device of the pretreatment step 2 uses a simple device such as a rotary screen, a granulating and thickening tank, and an inclined wedge wire screen which is more energy-saving than a centrifugal separator. The injection amount of the polymer 13 is S
Although it is about 1.0% of S (suspended solids), it differs depending on the type of solid-liquid separator and sludge properties, so it is necessary to determine the appropriate amount by changing the injection amount at the beginning of operation and by mistake.
Depending on the properties of the septic tank sludge 10, solid-liquid separation can be performed without adding the polymer 13. In the pretreatment step 2, sludge relating to organic wastewater treatment such as septic tank sludge, groundwater sludge of surplus sludge, and agricultural settlement wastewater sludge can be treated.

If the anaerobic digestion process 4 becomes unstable due to, for example, overload conditions,
Although not shown, it can be introduced into the dehydration step 20 to perform a dehydration treatment.

The urine 1 may be injected into the solid-liquid separation apparatus in the form of coagulated sludge 33 in a mixed state. Alternatively, the urine 1 may be introduced separately at different injection time zones.

The garbage-containing combustibles 15 are introduced into the anaerobic digestion step 4 after the garbage bag is crushed in the pre-treatment step 16 and separated and removed into combustibles 19 such as metals 18 and plastics. Is done. A conventional device such as a crusher, a separator, or a magnetic separator can be used as the separation and removal device for separating and removing the combustible material 19 such as metal 18 and plastic from the garbage-containing combustible material 15.

The effluent from the anaerobic digestion step 4 is separated in a dehydration step 20 into a dehydration separation liquid 21 and a dehydration sludge 22. As a result, impurities 26 such as plastics in the compost are removed, and a product compost 27 is produced. Separable combustibles 19, impurities 26
Is introduced into the solid fuel production device 28, and the solid fuel 29 is produced.

In the dewatering step 20, it is necessary to obtain a dewatered sludge 22 having a low water separation rate suitable for composting. Therefore, a sludge dewatering polymer 30 is injected at about 1.0% of SS, and centrifugal dewatering, which is a conventional dewatering apparatus, is performed. Water content by a dehydrator such as a press, belt press, screw press, filter press, etc.
%, Preferably around 70%.
As the impurity removing device 25, a rotating screen, a vibrating screen or the like is recommended. As the solid fuel production device 28, a high-pressure compression molding machine that is currently spreading is recommended.

The biogas 30 'generated from the anaerobic digestion step 4 is stored in a gas tank 32 after hydrogen sulfide in the gas is removed by a desulfurizer 31, and is used for power generation.

Although not shown, the coagulated sludge 33 in the advanced treatment step 8 is preferably concentrated in a concentration tank or directly introduced into the dewatering step 20. This is because the coagulated sludge 33 is occupied by a biologically inactive substance that hardly undergoes anaerobic digestion. On the other hand, if the coagulated sludge 33 is concentrated by introducing it into the pretreatment step 2 together with the septic tank sludge 10, the concentration tank can be omitted, and such a method is also recommended.

FIG. 2 is a diagram showing an example of the flow of the method for treating human waste, kitchen waste, and sludge according to the present invention. Pretreatment process 2-1 in which human waste 1 is provided with a solid-liquid separation device such as a rotary screen.
The coarse solids in the human urine 1 are removed, and the sieve residue (coarse solids) is introduced into the methane fermentation tank 4-2 in the anaerobic digestion step 4 via the sieve residue / sludge pipe 3. The filtrate 14-1 from which impurities have been removed is processed via the storage tank 5 in the same manner as in FIG.

Septic tank sludge 10 and excess sludge 11 from nitrification and denitrification step 6 are agglomerated by polymer (organic polymer flocculant) 13 injected into mixing tank 12, and then pretreatment step 2-
The separated sludge is introduced into an anaerobic digestion step 4 through a sieve residue / sludge pipe 3. The filtrate 14-2 is processed in the same manner as the filtrate 14-1 via the storage tank 5.
When a granulation concentration function is added to the mixing tank 12, the sludge can be concentrated and separated in the mixing tank 12, so that the pretreatment step 2-2 can be omitted.

In the pretreatment step 16, the garbage-containing combustibles 15 are separated into garbage bags, separated into combustibles 19 such as metals and plastics, and after the garbage content rises, the acid fermentation in the anaerobic digestion step is performed. It is introduced into the tank 4-1. A circulating separation liquid (a part of the dehydration separation liquid 21) 21-1 for adjusting the SS concentration and supplying hot water is injected into the acid fermentation tank 4-1.
The concentration is adjusted to around 15%. It is recommended that the water temperature of the acid fermentation tank 4-1 be about 55 ° C.
1 may be heated to 55 ° C. or more corresponding to the temperature of the inflow kitchen waste.

In the acid fermentation tank 4-1, the acid fermentation of the garbage proceeds to promote the methane fermentation in the subsequent methane fermentation tank 4-2. In the methane fermentation tank 4-2, by adjusting the stirring intensity, lightweight impurities such as plastics can float, sediment the weight of soil and the like during the stagnation period of the garbage, and can be separated and removed. It can also have a function as a pretreatment step of the contaminant of 4-2. The floating matter of the acid fermenter 4-1 is periodically discharged,
The dehydration process can be performed in the dehydration step 20.

The total temperature of the methane fermentation tank 4-2 is 5
It can be about 5 ° C. Example 1 Next, an example in which human waste, septic tank sludge, and sorted garbage are treated based on FIG. 2 will be described. Treatment conditions Human waste 10 m ³ / day Septic tank sludge 10 m ³ / day Excess sludge 6.5 m ³ / day Separated kitchen waste 10 t / day Pretreatment process Rotary screen Aperture 0.7 mm Cationic polymer injection amount (for sludge) vs. SS Ratio 1.0% Filtrate treatment system Biological treatment process Nitrification liquid circulation method Advanced treatment process Aggregation treatment with ferric chloride and activated carbon treatment Total amount of sewage / separated sludge 2.1 m ³ / day Sieve residue / sludge mixed concentration 6 ~ 12% sorting garbage pre-treatment machine Selective crushing and sorting equipment Impurities 30% (3t) Garbage 70% (7t) Acid fermentation tank (vertical screw stirrer, with sediment discharge pipe) Effective volume 20m ³ Water temperature 55 ° C Circulating nitrification desorbed liquid injection amount 12.1 m ³ / day Methane fermentation tank (with gas stirring equipment) Effective volume 320 m ³ Water temperature 55 ° C Dehydrator Screw press dehydrator Injection amount of cationic polymer (for sludge) vs. SS 1.0% Composting device Buddle type fermenter Dirt removal device Vibrating sieve Solid fuel conversion device Compression molding machine Generator Gas engine generator

Processing result Biogas generation 919 m ³ / day (methane content 65%) Gas power generation 1324 kwh / day Compost production 2.8 t / day (water content 30%) Solid fuel production 5.8 t / day Acid Fermenter sediment discharge 20 L / 7 days The results of treatment of the night soil and the filtrate of the septic tank sludge are shown in FIG.

As described above, it has been found that a large amount of biogas can be generated by the present invention, and that the power of the entire treatment facility can be almost self-sufficient by gas power generation. Night soil and impurities in septic tank sludge are separated silently in the separation step 2.
5, the product compost 27 and the contaminants 26 were distributed. However, neither the product compost 27 nor the contaminants 26 had an unpleasant odor due to human urine, and the appearance was hygienic. As a result of compression molding after mixing the separated combustibles 19 with the contaminated portion 26, a solid fuel with excellent ignitability and high calories was produced.

In addition, human waste, septic tank sludge, and excess sludge are shown in FIG.
As a result of performing processing under the same conditions as in Example 1 after performing the processing in the preprocessing step 2 of Example 1, the same processing results as in Example 1 were obtained.

[0035]

[Effect of the Invention] Since the night soil sieve residue can be treated without dewatering by a dehydrator such as a screw press, installation and operation management of the dehydrator become unnecessary.

Since dirt and malodorous substances adhering to the excrement of human waste can be decomposed and removed in the anaerobic digestion step, compost or solid fuel can be made without urine odor and sanitary.

Although the anaerobic digestion treatment method has been constructed as a main technology of human waste treatment, it is not suitable for removing nitrogen and phosphorus which are deeply impregnated in human waste, and has not been constructed at present. In the present invention, denitrification of human wastewater,
Since dephosphorization is performed and biogas energy can be obtained for the treatment, it is possible to denitrify and dephosphorize excreta and sludge filtrate at low treatment cost.

The sludge generated in the treatment of human waste by subjecting kitchen waste to methane fermentation (hereinafter simply abbreviated as sludge) alone can greatly increase the insufficient treatment energy.

Since the amount of sludge and kitchen garbage can be reduced by anaerobic digestion, equipment costs and processing costs related to the processing of sludge and kitchen garbage can be reduced.

The digestion / desorption liquid, which is the biggest problem that methane fermentation of kitchen waste has not been put into practical use economically, can be highly treated with a small treatment cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a flow example of a method for treating human waste, kitchen waste, and sludge of the present invention.

FIG. 2 is a diagram showing a flow example of a method for treating human waste, kitchen waste, and sludge according to the present invention.

FIG. 3 is a view showing the results of treating filtrate of human waste and septic tank sludge according to the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiro Suzuki 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Hideo Aishima 11-1 Haneda Asahi-cho, Ota-ku, Tokyo EBARA CORPORATION

Claims (6)

[Claims] 1. A method for treating human waste, kitchen waste, and sludge, comprising the following steps (a) to (f). (A) a pretreatment step of solid-liquid separation of human waste mixed with sludge; (b) an anaerobic digestion step of directly anaerobic digestion of the solid matter separated in the treatment step without dehydration; (c) animal and plant residues and the above The anaerobic digestion step of anaerobic digestion of garbage containing solids; (d) a dehydration step of dehydrating the anaerobic digestion step effluent into solids and separation water; (e) a separation water of the pretreatment step A biological treatment step of biologically oxidizing and denitrifying water separated from the dehydration step. 2. The treatment of night soil, kitchen waste and sludge according to claim 1, wherein the pre-treatment step is to mix the sludge and the urine with the urine simultaneously or separate the sludge into the solid and liquid at different time periods. Method. 3. The human waste, kitchen garbage, and sludge according to claim 1, wherein the pretreatment step comprises a sludge solid-liquid separation step for the sludge and a night soil solid-liquid separation step for the night soil. Processing method. 4. The method for treating night soil, kitchen waste and sludge according to claim 1, wherein a coagulant is injected into the sludge in the treatment step. 5. The anaerobic digestion step comprises acid fermentation (solubilization).
The method for treating night soil, kitchen waste and sludge according to any one of claims 1 to 4, comprising a step and a methane fermentation step subsequent to the step. 6. The sludge discharged from the pretreatment step is adjusted to have a solid content of 12% or less.
6. The method for treating night soil, kitchen waste, and sludge according to any one of Items 1 to 5.