JP3835930B2 - Organic waste treatment methods - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating organic waste in which a plurality of types of organic waste having different properties and concentrations are treated in the same treatment system, and useful substances are recovered.
[0002]
[Prior art]
Conventionally, organic waste has been recycled. For example, JP-A-9-201699 describes properties such as human waste, septic tank sludge, sewage sludge, agricultural sludge, livestock manure, garbage, food waste, etc. In other words, a method is disclosed in which organic wastes having different concentrations are processed in the same system to recover useful materials and recycle them.
[0003]
This method is as shown in FIG. 3. Human waste, septic tank sludge, agricultural sludge, sewage sludge, and livestock manure are removed in the debris process # 31, and liquid waste is obtained in the solid-liquid separation process # 32. 31 and the dehydrated sludge 32, and the liquid waste 31 is subjected to BOD decomposition in the biological treatment step # 33 and denitrified as necessary, and suspended matter is removed in the solid-liquid separation step # 34, and the advanced treatment step # In 35, heavy metals such as COD, pigment components and iron / manganese are removed and disinfected to be discharged or reused.
[0004]
On the other hand, food waste and food waste are crushed in the crushing / sorting step # 36, and after separating plastic bags, trays, etc., mixed with the dehydrated sludge 32 described above, fermented in the anaerobic fermentation step # 37, The generated methane gas 33 is collected and used in the form of electricity or heat by the power generation process # 38, etc., and the digested sludge 34 is converted to the dewatered sludge 35 in the dehydration process # 39 and sent to the composting process # 40, etc. In addition, it is recovered as solid fuel or dry sludge, and the dehydrated filtrate 36 is sent to the biological treatment step # 33 for processing.
[0005]
[Problems to be solved by the invention]
However, since the digested sludge 34 generated in the anaerobic fermentation process # 37 as described above has few organic components, the amount of heat and fertilizing components may be insufficient when composting the dewatered sludge 35 that has been dehydrated. is there. On the other hand, since phosphorus moves to the dehydrated filtrate 36 side, the phosphorus removal operation must be performed in the biological treatment process # 33 for treating the dehydrated filtrate 36 or other water treatment process.
[0006]
Moreover, there is a problem that food waste and food waste that has been crushed and sorted contain a large amount of small anaerobic fermentation inadequate materials such as fish bones, which accumulate in the fermenter.
[0007]
The present invention solves the above problems, and can efficiently separate anaerobic fermentation inadequate materials such as phosphorus and fish bones. Organic waste that can effectively use separated phosphorus and increase the efficiency of processing can be achieved. The object is to provide a processing method.
[0008]
[Means for Solving the Problems]
In order to solve the above problem, the organic waste processing method according to claim 1 of the present invention treats a plurality of types of organic waste having different properties and concentrations in the same processing system, and recovers useful substances. At this time, solid organic waste such as garbage is led to a crushing process and crushed, and the crushed material is mixed with sludge-like organic waste such as urine and septic tank sludge. Leading to a two-component coagulation dehydration process in which two types of coagulant are added, the phosphorus contained in the mixture is aggregated, separated into a solid substance containing aggregated phosphorus and a desorbed liquid, and separated phosphorus-containing solid Biomass such as methane generated by introducing the product into the composting process, fermenting it under aerobic conditions, collecting it as compost, introducing the effluent into the anaerobic fermentation process, fermenting it under anaerobic conditions To collect And it features.
[0009]
The organic waste processing method according to claim 2, in the crushing step, crushes organic waste by a compression crusher that has a fine crushing discharge hole and performs crushing by high pressure that is instantaneously loaded. It is characterized by that.
[0010]
The method for treating organic waste according to claim 3 is characterized in that organic waste having a low biodegradation rate is solubilized and liquefied before the two-component coagulation dehydration step.
According to the configuration of claim 1 described above, the two-component coagulation dehydration is performed, so that the phosphorus in the mixture is surely transferred to the solid side, and this phosphorus-containing solid is fermented under aerobic conditions. The organic matter present in the fermented material efficiently fermented while generating a large amount of heat, and a good compost sufficiently containing nitrogen and phosphorus as fertilizing components can be obtained. Further, since the desorbed liquid from which phosphorus has been removed is fermented under anaerobic conditions, a phosphorus removing operation for the dehydrated filtrate desorbed from the generated digested sludge is unnecessary.
[0011]
According to the configuration of claim 2, organic waste that has been difficult to be crushed in the past is also discharged while being crushed finely in the crushing discharge hole by a high pressure to be applied. Since it cannot enter the crushing discharge hole even under high pressure, it remains in the apparatus and is automatically separated. Finely crushed organic waste is efficiently fermented and organic components are recovered at a high rate.
[0012]
According to the configuration of claim 3, since the organic waste having a low biodegradation rate is liquefied in advance, the liquefied organic waste is subjected to a two-component coagulation dehydration step and an anaerobic fermentation step and compost. It can be efficiently fermented in any of the conversion steps.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
Fig. 1 shows the flow of recovering useful materials by recycling organic waste such as human waste, septic tank sludge, sewage sludge, agricultural sludge, livestock manure, garbage, food waste, etc. in the same treatment system. Indicates.
[0014]
Sludge-like organic waste such as human waste, septic tank sludge, sewage sludge, agricultural sludge, livestock manure, etc. is led to the concentration step # 1, and depending on the nature, organic polymer flocculant 1 is added and solid-liquid separated. Concentrated sludge 2 and separated liquid 3 are used. This concentration step # 1 may be performed by granulation concentration, screen concentration or the like according to the desired sludge moisture content, and can be omitted if not necessary. A debris process may be provided before the concentration process # 1.
[0015]
The separation liquid 3 is introduced into the biological treatment step # 2, and BOD decomposition and denitrification are performed as necessary, and the biologically treated water 4 is guided to the subsequent treatment, not shown.
The excess sludge 5 generated in the biological treatment step # 2 is appropriately extracted, but since the biodegradability is low, it is led to the solubilization step # 3 together with other low biodegradable organic wastes, and solubilized. Liquefaction and low molecular weight. As the solubilization treatment, maintain at about 70 to 80 ° C. for 3 days; maintain at 70 ° C. and high temperature and high pressure of about 0.3 MPa; add alkali such as caustic soda and slaked lime and maintain at about 70 ° C .; Various methods such as blowing; maintaining at 130 to 175 ° C. are exemplified. This solubilization step # 3 is not necessarily performed, but biodegradability can be enhanced by liquefaction and low molecular weight. The obtained liquefied product 6 is sent to the biological treatment step # 2 through the concentration step # 1 for processing, or when there is no concentration step # 1, it is processed as described later.
[0016]
On the other hand, other organic wastes that contain unfit fermentation materials such as food waste, food waste, etc., or that contain inhomogeneous solids, are compressed and crushed in the crushing / sorting step # 4. To do.
[0017]
The crusher to be used is, for example, a compression crusher as shown in FIG. 2, and the crushing object introduced from the inlet 111 into the chamber 113 by the feeder 112 is uniformly applied with pressure depending on the properties. After being adjusted with dilution water as described above, it is compressed at a high pressure of 200 to 250 kg / cm ² that is instantaneously loaded by the hydraulic cylinder 114, and extruded from a fine crushing discharge hole (not shown) formed in a slit shape. In this way, it is crushed into fine particles (becomes paste or flakes depending on the properties of the object to be crushed), discharged through the crushed discharge port 115, and the residue is separately taken out from the residue discharge port 116. ing.
[0018]
For this reason, organic waste such as garbage is discharged as fine particles 7 that are flowable and have a particle size of 1 to 2 mm, and cannot be crushed, such as plastics, metals, stones / sand, fish bones, etc. The unsuitable fermentation product 8 is automatically separated at the same time by remaining. The moisture content of the unsuitable fermentation material 8 is low, and organic waste adheres to the unsuitable fermentation material 8 very little. Depending on the properties of food waste and food waste, a rough crushing step can be provided to increase the input amount to the compression crusher and increase the processing amount.
[0019]
Next, this fine particulate matter 7 and the above-described concentrated sludge 2 (in some cases, sludge-like organic waste or liquefied matter 6) are mixed, and the mixture 9 is guided to the two-component coagulation dehydration step # 5 and centrifuged. While introducing into dehydrators, such as a dehydrator, a belt press, a filter press, and a screw press, two kinds of flocculants 10 and 11 are sequentially added to the mixture 9 in the introduction path, mixed, and dehydrated.
[0020]
At this time, it is essential that one flocculant 10 has a phosphorous aggregating effect, and the other flocculant 11 may or may not have a phosphorous aggregating effect. Examples of the flocculant 10 include sulfuric acid bands, aluminum flocculants such as aluminum chloride, aluminum sulfate, and TK floc, iron-based flocculants such as polyiron, ferrous sulfate, ferric sulfate, and ferric chloride, magnesium chloride. As the inorganic flocculant such as slaked lime and the flocculant 11, organic polymer flocculants such as amphoteric polymers and cationic polymers can be suitably used. By adding such two kinds of flocculants 10, 11, the phosphorus contained in the mixture 9 is reliably agglomerated, the dehydrating property of the mixture 9 is improved, and the solids 12 containing the agglomerated phosphorus are detached. The liquid 13 is well separated.
[0021]
The separated phosphorus-containing solid material 12 is led to the composting step # 6, fermented under aerobic conditions, and recovered as compost 14. At that time, the fine particulate matter 7 is not only finely divided by compression crushing as described above, but also part of the cell membrane is destroyed, so that the biodegradability is very large, and conventionally, crushing is difficult. Organic waste that has been excluded as being, and organic waste that has been eliminated by adhering to the unsuitable fermentation 8 are also included in the fine particulate matter 7, as well as garbage and food waste In addition, there is an effect of mixing different components of human waste, septic tank sludge, etc., such as trace elements (Fe, Ni, Co, etc.), while abundant organic matter generates a large amount of heat. Fermentation efficiently, and good compost 14 sufficiently containing nitrogen and phosphorus as fertilizing components is obtained.
[0022]
The separated effluent 13 is introduced into an anaerobic fermentation step # 7 and fermented in an acid fermentation tank and then in a methane fermentation tank under anaerobic conditions, but the detachment liquid 13 containing no solid content is used as a raw material. Both acid fermentation and methane fermentation are fast. The biogas 15 such as methane generated in the methane fermenter is recovered, desulfurized, etc., and then used in the same manner as before.
[0023]
The fermented sludge 16 generated in the methane fermenter is guided to the dehydration step # 8 and dehydrated and recovered as a dehydrated cake 17 to be used as solid fuel or the like as before, or mixed with the phosphorus-containing solid material 12. May be composted. The detachment liquid 18 is returned to the biological treatment step # 2 for processing. However, since phosphorus is not contained, a conventional phosphorus removal operation is unnecessary.
[0024]
In addition, the organic substance load supplied to the anaerobic fermentation process # 7 can be adjusted by adjusting the dehydration rate in the two-component agglomeration dehydration process # 5, and thus the size of the fermenter can be reduced.
[0025]
In the anaerobic fermentation process # 7, the fermentation can be further promoted by increasing the concentration of methane bacteria in the fermenter. For example, the UASB method (upward flow sludge blanket method) or the membrane separation type can be used. A fermenter can be used.
[0026]
【The invention's effect】
As described above, according to the present invention, a mixture of crushed material obtained by crushing garbage and human waste, septic tank sludge, etc. is guided to a two-liquid coagulation dehydration step to aggregate phosphorus contained in the mixture, Separation into solids containing aggregated phosphorus and detachment liquid, and the phosphorus-containing solids are fermented under aerobic conditions, so abundant organic matter will be efficiently fermented while generating a large amount of heat. In addition to obtaining good compost that sufficiently contains nitrogen and phosphorus as fertilizing components, the amount of heat supplied from the outside for adjusting the fermentation environment can also be reduced. Further, since the desorbed liquid from which phosphorus has been removed is fermented under anaerobic conditions, the phosphorus removal operation is not necessary for the dehydrated filtrate desorbed from the digested sludge.
[0027]
In addition, since the compression crusher was used, organic waste, which was difficult to crush in the past, can be finely crushed and efficiently fermented, and organic components can be recovered at a high rate. Inferior fermentation materials such as bones can be automatically separated at the same time, and transfer of inappropriate fermentation materials to acid and methane fermentation tanks and accumulation in the tank can be prevented. Is possible.
[0028]
In addition, organic waste with a low biodegradation rate was solubilized and liquefied before the two-liquid coagulation dehydration process, so this liquefied organic waste was subjected to the two-liquid coagulation dehydration process. In either an anaerobic fermentation process or a composting process, the fermentation can be carried out efficiently.
[Brief description of the drawings]
FIG. 1 is a flowchart illustrating a method for treating organic waste according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a schematic configuration of a compression crusher used in the organic waste processing method shown in FIG. 1;
FIG. 3 is a flowchart showing a conventional organic waste processing flow.
[Explanation of symbols]
5 Excess sludge 6 Liquefaction material 7 Crushed material 9 Mixture
10,11 flocculant
12 Solid
13 Release liquid
14 Compost
15 Biogas

Claims (3)

When processing multiple types of organic wastes with different properties and concentrations in the same treatment system and collecting useful materials, solid organic wastes such as garbage are led to the crushing process and crushed. As a mixture with sludge-like organic waste such as human waste, septic tank sludge, etc., at least one leads to a two-liquid coagulation dehydration process in which two types of coagulant having a phosphorus coagulation effect are added, and the phosphorus contained in the mixture Is separated into solids containing aggregated phosphorus and desorbed liquid, the separated phosphorus-containing solids are introduced into the composting process, fermented under aerobic conditions, recovered as compost, and desorbed A method for treating organic waste, characterized in that a liquid is introduced into an anaerobic fermentation process, fermented under anaerobic conditions, and biogas such as methane generated is recovered. 2. The organic waste according to claim 1, wherein in the crushing step, the organic waste is crushed by a compression crusher having a fine crushing discharge hole and performing crushing by high pressure that is instantaneously loaded. Processing method. The organic waste processing method according to claim 1, wherein organic waste having a low biodegradation rate is solubilized and liquefied before the two-component coagulation dehydration step.

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