KR20080032292A - Method and apparatus for producing resources from food waste - Google Patents

Abstract

A method and an apparatus for producing resource from food waste are provided to produce liquid fertilizer and manure from the food waste, and generate cleaned water for treatment of sewage and drainage of reused water. Food waste is fermented under a high-temperature and aerobic condition, thereby generating fermented materials. A first condensation process is performed on the fermented materials to generate condensed materials. A first solid-liquid separation process is performed on the condensed materials to separate the condensed materials into solid materials and liquid materials. A second condensation process and a second solid-liquid separation process are performed on the separated liquid materials. Solid materials obtained by the second solid-liquid separation process are removed. An advanced treatment process is performed on liquid materials obtained by the second solid-liquid separation process, thereby generating enriched water and filtered water. The enriched water is separated, and the filtered water is drained. Further, the fermentation step is performed at 60 to 70°C, pH of 8 to 9, for 24 to 48 hrs.

Description

Method and apparatus for producing resources from food waste

1 is a schematic process diagram of a food waste recycling method according to the present invention.

The present invention relates to a method for recycling food waste, and more specifically, using food waste, not only can produce liquid fertilizer and compost, but also can produce clean water capable of sewage-related and heavy water discharge, excellent calorific value The present invention relates to a food waste recycling method capable of producing solids and biogas.

Food waste has 80 ~ 85% moisture content and easily decomposes, causing odors and sewage, so it is difficult to separate and transport.In case of landfill, a large amount of leachate flows out and causes secondary environmental pollution such as groundwater pollution. Not only does it cost a lot of money, but the calorific value is low even when incinerated, and there is a problem such as the additional use of auxiliary fuel due to the incineration temperature decrease.

In 2003, the average amount of food waste generated in Korea is 15,075 tons per day. The disposal of such food waste has been largely dependent on landfill, but since 2005, due to the depletion of the landfill, direct disposal of food waste has been banned. Therefore, it is urgent to develop resources for the disposal of food waste and to effectively deal with it. Is required.

In general, food waste treatment includes anaerobic digestion, composting, microbial fermentation, and wet / dry feed, which produce methane and biogas. Ii) a method of entrusting to a marine dumper, iv) a method of concatenating or consigning with sewage treatment after primary treatment, and iv) a method of treating effluent in the treatment plant.

However, due to the characteristics of food wastes that generate many by-products, generate odors, are difficult to incinerate and landfill, and have low weight reduction, conventional food waste recycling methods provide the cause of livestock mortality in feed, and high water content. Due to its content and low calorific value, it causes secondary pollution problems when incinerated, and due to high salinity, dilution of process water is inevitable when composting. There was a problem that this was low.

The present invention is to solve the problems of the prior art as described above, by using food waste, not only can produce excellent liquid fertilizer and compost, but also obtain clean water that can discharge sewage system and heavy water discharge, It is an object of the present invention to provide a food waste recycling method and apparatus for producing solids and biogas having excellent calorific value.

The present invention to achieve the above object, the step of fermenting food waste under high temperature aerobic conditions; Performing a first flocculation process on the fermentation product; Separating a solid phase and a liquid phase by performing a first solid-liquid separation process on the agglomeration product; Separating the solid phase and performing a second flocculation process and a second solid-liquid separation process on the liquid phase; Separating the solid phase obtained in the second solid-liquid separation process and performing a high treatment process on the liquid phase; And separating the R / O concentrated water obtained in the advanced treatment process and discharging the permeate.

In addition, the present invention is another embodiment for achieving the above object, a high-temperature exhalation fermenter for fermenting food waste under high temperature aerobic conditions; An aggregator performing a coagulation process for the product of the high temperature expiratory fermenter; A solid-liquid separator for separating a solid phase and a liquid phase by performing a solid-liquid separation process on the resultant of the flocculator; And an advanced processor for separating the solid phase obtained from the solid-liquid separator and performing a high-treatment process for the liquid phase, and the coagulation process and the solid-liquid separation process are performed again for the liquid phase of the result of the solid-liquid separator. After the advanced processing is carried out, the R / O concentrated water is separated from the result of the advanced processor, and the permeate is discharged to provide a food waste recycling apparatus.

According to the present invention, it is possible not only to produce useful resources such as liquid fertilizer and compost by using food waste, but also to obtain a high degree of clean water capable of direct discharge to sewage.

Hereinafter, the food waste recycling method according to the present invention will be described in more detail.

1, a schematic process diagram of a food waste recycling method according to the present invention is shown.

Referring to FIG. 1, the method according to the invention first performs fermentation on food waste under high temperature aerobic conditions. This increases the coagulation efficiency in the formation of a solid in a later coagulation step, and in this step, almost all of the volatile lower fatty acids in the fermentation effluent are removed, thereby exhibiting an excellent odor reduction effect. In addition, the fermentation process may perform a function of stabilizing the desorption liquid of the unstable food waste in a state capable of subsequent processing.

Preferably, the fermentation step is carried out in a temperature range of 60 ℃ to 70 ℃, if the fermentation temperature is less than 60 ℃ there is a problem of a second infection, such as pathogenic microorganisms, if exceeding 70 ℃ odor generation And it is not preferable because there is a problem that cannot be fermented. In particular, in the present invention, since the fermentation process is performed at a high temperature as described above, most fermentative microorganisms can be killed in the fermentation step.

The pH of the fermentation step is preferably maintained at 8.0 to 9.0, if the pH is less than 8.0, there is a problem of immature, if it exceeds 9.0 there is a problem of the fermentation state due to overaeration is not preferred. On the other hand, the desorbing liquid of the incoming food waste usually has a pH of about 4.0.

In the aerobic fermentation step as described above, microorganisms such as Bacillus bacteria and high temperature Bacillus bacteria are used.

Preferably, the fermentation step is carried out for 24 to 48 hours.

Next, a first flocculation process is performed on the fermentation product that has undergone the fermentation step. The primary flocculation process is performed by adding ferric sulfate (Fe2 (SO4) 3) and a polymer flocculant to the fermentation product. As the polymer flocculant, those commonly used in the wastewater treatment industry may be used. Although, for example, polymer flocculants such as Hi-pax, HanFloc-P or Yangfloc may be used. In addition, preferably, the mixing weight ratio of the ferric sulfate and the polymer flocculant is 1: 0.01 to 1: 0.02.

Subsequently, the first solid-liquid separation process is performed on the resultant of the first coagulation process, whereby the solid phase and the liquid phase are separated. The solid-liquid separation process may be performed using a conventional filter press, etc., and as a result, it is possible to obtain a solid phase and a sewage-linkable liquid phase including a cover material and RDF (Refuse Derived Fuel).

At this time, the solid phase has a high calorific value and a large amount of ash generated, and thus may be usefully used as a regenerated fuel. In addition, the liquid phase can be connected to sewage, but in order to convert to a high degree of clean water capable of heavy water discharge, the coagulation process and the solid-liquid separation process must be performed again.

Therefore, in the present invention, the secondary coagulation process is performed again on the liquid phase obtained in the primary coagulation process, and the same ferric sulfate and polymer coagulant as the primary coagulation process may be used in the secondary coagulation process. Here, the inflow water newly introduced through the fermentation step is mixed with the liquid phase, that is, the treated water, which has completed the first flocculation process and the first solid-liquid separation process, and the mixing ratio of the inflow water and the treated water is preferably 1: 0.5. Do.

Next, the solid phase obtained in the second solid-liquid separation process is separated and a high-treatment process is performed on the liquid phase.

The advanced treatment process is to separate the liquid phase into concentrated R / O water and reusable permeate using foil, and then recycle the R / O concentrated water again so that the liquid phase can be recycled. It means a treatment process to ensure that.

Subsequently, finally, the R / O concentrated water obtained in the above advanced processing step is separated, and the permeate is discharged to complete the food waste recycling method according to the present invention. At this time, the R / O concentrated water is recycled through the fermentation tank, pH control of the desorption liquid in the fermentation tank may be made by an external influent.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples are only for illustrating the present invention and do not limit the scope of the present invention.

<Example>

240 liters of the food waste was fermented for 24 hours at an operating temperature of 63.7 ° C. on average, and the pH of the fermentation stage was maintained at an average of 8.5. Table 1 schematically shows the characteristics of the influent flowing into the high temperature fermentation step and the discharge water after the high temperature fermentation step.

Item Influent Discharge Remarks Temperature 58.53 ℃ 68.33 ℃ Maintain high temperature fermentation pH 7.33 8.93 Good liquid composting TS (Total Solid) 5.09% 5.20% Primary pretreatment VS (Volatile Solid) 2.77% 2.63% Primary pretreatment VS / TS 45.54% 49.73% - Total Nitrogen (T-N) 2200 g 520 g 77% Total Phosporous (T-P) 380 g 170 g 54% Chemical Oxygen Demand (CODcr) 28000 g 6500 g 77% sCOD (Soluble Chemical Oxygen Demand) 11000 g 1500 g 87% Biochemical Oxygen Demand (BOD) 17000 g 7900 g 95% Volatile Fatty Acids (VFAs) 3700 g 68 g 98%

Subsequently, 1.5% of the total amount of ferric sulfate (Fe2 (SO4) 3) was added to the fermentation product, and Yangfloc 100mg / L to 150mg / L of Y company was added as a polymer coagulant to carry out the first aggregation process. . The first solid-liquid separation process was performed using the filter press (solidifying machine, Alpyeong machine) for the flocculation product.

The solid phase obtained in the solid-liquid separation process (about 10 kg to 100 kg throughput) was separated, and the first flocculation process and the first solid-liquid separation were performed on the liquid phase (90% of the throughput) and the fresh influent (90% of the total amount) from the fermentation step. In the same manner as the process, a second flocculation process and a second solid-liquid separation process were performed.

As a result of the second solid-liquid separation process, the treated water (90% of the throughput) and the solid phase (10% of the throughput) were obtained, and the obtained treated water was subjected to a high treatment process. In the advanced treatment process, a reverse osmosis membrane device (Greenwell Co., Ltd.) was used. R / O concentrated water (20% of the highly treated influent) and permeate (80% of the highly treated influent) were obtained in the advanced treatment process.

Tables 2 and 3 show the properties of the food desorption solution before performing the method according to the invention (Table 2) and the properties of the results of each step during the method according to the invention (Table 3).

Item Average pH 4.0 TS (%) 8 to 12 VS (%) 84 to 86 T-N (mg / L) 3,000 to 5,000 T-P (mg / L) 900 to 1,000 BOD5 (mg / L) 40,000-53,000 CODcr (mg / L) 100,000 to 120,000 SCODcr (mg / L) 80,000-100,000 CODMn (mg / L) 30,000-40,000 VFA (mg / L) 2,400-2,600

Item Agglomerated samples Primary filtrate Secondary filtrate Permeate Ph 7.57 7.29 4.48 5.31 SS (mg / L) Suspend Solid 25,129 1,043 203 0.0 T-N (mg / L) 2,332 1,492 1,352 50 T-P (mg / L) 767 25 1.4 0.1 BOD5 (mg / L) 7,785 2,718 2,089 1.0 CODcr (mg / L) 41,762 9,501 5,053 50 CODMn (mg / L) 21,000 4,000 1,035 39

According to the present invention, the food waste can be used to produce not only liquid fertilizer and compost, but also to produce clean water capable of sewage-related and heavy water discharge.

In addition, the solids produced in the process according to the present invention has an excellent calorific value and thus can be usefully resourceized, and biogas produced in the process can also be utilized as a useful resource.

Claims (14)

Fermenting food waste under high temperature aerobic conditions; Performing a first flocculation process on the fermentation product; Separating a solid phase and a liquid phase by performing a first solid-liquid separation process on the agglomeration product; Separating the solid phase and performing a second flocculation process and a second solid-liquid separation process on the liquid phase; Separating the solid phase obtained in the second solid-liquid separation process and performing a high treatment process on the liquid phase; And Separating the R / O concentrated water obtained in the high-treatment process, and discharge the permeate water. The method according to claim 1, wherein the fermentation step is carried out at a temperature range of 60 ℃ to 70 ℃. The method of claim 1, wherein the fermentation step, the pH of the food waste, characterized in that performed at 8.0 to 9.0. The method of claim 1, wherein the fermentation step is performed for 24 to 48 hours. The method of claim 1, wherein the primary flocculation process is a method of recycling the food waste, characterized in that by adding ferric sulfate (Fe2 (SO4) 3) and a polymer flocculant to the product of the fermentation step. The method of claim 5, wherein the mixing weight ratio of the ferric sulfate and the polymer flocculant is 1: 0.01 to 1: 0.02. The method of claim 1, wherein the freshly introduced inflow water through the fermentation step is mixed with the liquid phase having a ratio of 1: 0.5 and the liquid phase after the first flocculation process and the first solid-liquid separation process. . A high temperature aerobic fermenter for fermenting food waste under high temperature aerobic conditions; An aggregator performing a coagulation process for the product of the high temperature expiratory fermenter; A solid-liquid separator for separating a solid phase and a liquid phase by performing a solid-liquid separation process on the resultant of the flocculator; And Separation of the solid phase obtained in the solid-liquid separator, and equipped with a high processor for performing a high processing process for the liquid phase, For the liquid phase in the result of the solid-liquid separator, the high-treatment process is performed after the coagulation process and the solid-liquid separation process are performed again, R / O concentrated water is separated from the result of the advanced processor, permeate is discharged, characterized in that the food waste recycling apparatus. The apparatus of claim 8, wherein the fermentation in the high temperature exhalation fermenter is performed at a temperature in a range of 60 ° C. to 70 ° C. 10. The apparatus of claim 8, wherein the fermentation in the high temperature exhalation fermenter is performed at a pH of 8.0 to 9.0. 10. The apparatus of claim 8, wherein the fermentation in the high temperature exhalation fermenter is performed for 24 to 48 hours. The apparatus of claim 8, wherein the flocculating step of the flocculator is performed by adding ferric sulfate (Fe (SO)) and a polymer flocculant to the product of the high temperature expiratory fermenter. The food waste recycling apparatus of claim 12, wherein the mixed weight ratio of the ferric sulfate and the polymer coagulant is 1: 0.01 to 1: 0.02. The food waste recycling apparatus according to claim 8, wherein the inflow water newly introduced into the flocculator through the high temperature exhalation fermenter is mixed with the liquid phase which is the result of the solid-liquid separator at a mixing ratio of 1: 0.5.

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