FR2792330A1 - Decomposition of food waste, comprising periodically mixing the waste with aerobic bacteria on carriers - Google Patents

Abstract

A process for decomposing food waste comprises co-culturing obligate and facultative aerobic bacteria on sterile dry carriers, introducing food waste into a device containing the carriers in a predetermined amount per day for 6 months, and mixing the carriers and waste at regular intervals at 25 to 35 deg C. An Independent claim is also included for a device for decomposing food waste, comprising a receptacle made of thermally insulating material, a fermentation chamber having a waste chute with a sprung holding arm, a hexagonal axle extending across the fermentation chamber and having six agitator blades arranged at an angle of 60 deg (each blade having two auxiliary blades of triangular cross section) and a deodorizing device fitted inside the receptacle and connected to a gas outlet pipe.

Description

The present invention relates to a method and a device for destroying

  food waste at low and ordinary temperatures, using microbes. More particularly, the present invention relates to a method for destroying food waste completely and cleanly with little

production of foul odors.

  Food waste is an organic mass which can be almost completely broken down into lees if there are appropriate conditions given such as temperature and oxygen supply. For example, as food waste, consisting mainly of C, H, N and O, provides nutrients to microorganisms, if the organic waste is placed in a certain

  device or location in which various micro-

  organisms are abundant in an appropriate condition, the waste can ultimately be converted into construction sequences or end products such as C02, H20, NO2, and the like. So even if food waste is thrown away every day in a certain place or device, there is no pile of waste there for a period of time

significant.

  When condition factors, such as temperature, oxygen, nutrition and the like are appropriately provided, microbial populations with balanced proliferation increase about double in a certain period of time. After this exponential phase, they excrete enzymes outside their cells. These extracellular enzymes (exoenzymes) are inactivated after their function to break down macromolecules into other

  smaller that can be digested by microbes.

  Since enzymes are necessary for the growth and proliferation of microbes, they are expressed continuously during the proliferation of microbes. So microbes can be used for easy destruction

  food waste, without producing pollution.

  Organic matter is generally broken down aerobically or anaerobically depending on the fermentation patterns of the enzymes. Aerobic fermentation does not produce foul odors, but is slow. On the other hand, anaerobic fermentation produces a large amount of gas, giving an odor

  foul-smelling, but leads to rapid catabolism.

  With the background in mind, the object of the present invention is to provide a method for

  properly destroy food waste.

  Another object of the present invention is to provide a device in which a large quantity of food waste is continuously destroyed and

properly.

  According to one aspect of the present invention, there is provided a method for destroying food waste at low and ordinary temperatures, comprising the steps of: joint culture of aerobic and optional active bacteria, grown together on sterile dry carriers; introduction into the device comprising the carriers of a predetermined quantity of food waste per day for six months; and mixing of the supports with the food waste introduced, at regular intervals and at a temperature of 25 to 35 C, as a result of which the food waste is decomposed for 6 months by the action of fermentation and / or oxidation of bacteria on media. According to another aspect of the present invention, there is provided a device for destroying food waste at low and ordinary temperatures, comprising: a container made of a thermally insulating material; a fermentation tank with a waste chute and a hexagonal axis, the waste chute being opened and closed by a cover with a spring-type content so as not to shock the fermentation tank, the hexagonal axis extending through the fermentation tank and having six stirring fins on each of which are mounted 2 auxiliary fins having a cross section A, the stirring fins being arranged at an angle of with additional adjacent and functioning fins so as to mix the food waste, together with the auxiliary fins; and deodorizing means with an exhaust pipe, the fermentation tank and the deodorizing means being installed inside the container, where food waste can be completely

  decomposed into producing little offensive odors.

  The above objects and aspects of the invention, as well as others, will become apparent to

  from the following description of modes of

  embodiment, taken with reference to the accompanying drawings, in which: Figure 1 is a partially exploded perspective view showing the device of the present invention; Figure 2 is a rear perspective view showing a heater mounting device, according to a first aspect of the present invention; Figure 3 is a rear perspective view showing a device for mounting a fan heater, according to a second embodiment of the present invention; Figure 4 is a sectional view showing the device according to the first embodiment, taken along the line AA '; and Figure 5 is a partially enlarged perspective view showing a fermentation tank according to the

  second embodiment of the present invention.

  The present invention relates to a method for cleaning food waste by the use of microbes. Microbes are saprophytic bacteria that are found everywhere in soils, rivers and currents. Are available those which can decompose organic matter, such as carbohydrates, proteins, fats, starches, cellulose, etc., and those which are preferred are

aerobic or optional.

  After culture in a broth, the available bacteria are inoculated and cultivated jointly on supports. As carriers, sawdust, rice bran, peat, wood chips, and porous ceramic beads are useful. Before inoculation, the supports are sterilized and dried until they

have a water content of 10%.

  These supports are placed in a space which is maintained at a temperature of 25 to 35 C, and mixed with food waste at regular intervals for a certain period of time. During this time, food waste is decomposed by the actions of oxidation and fermentation of bacteria cultivated jointly on the supports. For this purpose, a device is provided, which is equipped with a temperature control system, a mixing system, an air supply system and a deodorizing system,

  in accordance with the present invention.

  A better understanding of the present invention can be obtained by the following examples which are presented for purposes of illustration, but should not be understood as constituting a limitation of the present invention.

Example I

  Selection of microbes First group (Aerobacter; Enterobacter spp.) - The selection was made for bacteria which can oxidize food waste consisting mainly of C, H and O into carbon dioxide and water in the presence of oxygen molecules, as shown by (CH20) x -> C02 + H20, and can ferment them in the absence of molecules

  oxygen, as represented by (CH20) x -> CH3COOH.

  Second group (Bacillus spp.) - During proliferation, strains belonging to this group excrete exo-enzymes which break down extracellular macromolecules into smaller molecules which can be transported inside the cells of their own strain or those of 'other strains. Examples of exo-enzymes include lipases, proteases and amylases which hydrolyze lipids, proteins and starches, respectively. Thus, the strains selected from this group can convert suspended solids, such as fats, proteins and starches, into solid suspended solids which can now be used for digestion.

intracellular by microbes.

  Third group (Pseudomonas spp.) - Like the bacteria in the first group, the bacteria in this group oxidize food waste consisting mainly of C, H and O to carbon dioxide and water, as expressed by (CH20) x -> C02 + H2O. Furthermore, the present bacteria can decompose the waste resulting from petrochemical materials, such as H2S,

  harsh detergents (ABS), mild detergents (LAS), N-

  hexane, phenol, hydrocarbons, etc. Fourth group (Cellulomonas spp.) - Bacteria of this genus hydrolyses cellulose by conversion of o-glycosidic bonds into P-glycosidic bonds which

  are used more easily by bacteria.

  Fifth group (Rhodopseudomonas spp.) - In an aerobic condition, the present bacteria function like the Pseudomonas bacteria. On the other hand, in the absence of oxygen molecules, the bacteria undergo a fermentative proliferation. During fermentation, the energy source (CH20) x is broken down into two stages: (CH20) x -> CH3COOH; CH3COOH -> CH4 + C02. The selection was made for bacteria which can maintain this fermentation in two stages and carry out the CH3COOH -> C02 + H2O reaction. The selected strains could play an important role in

  elimination of the foul odor factor, CH4 gas.

  Sixth group (Nitrosomonas spp.) - When proteins are broken down, ammonium (NH3-N) is produced. These nitrifying bacteria oxidize ammonium to nitrite (NO2-N). This oxidation must be carried out in the presence of oxygen molecules as follows: 2NH3 + 302

-> 2NO2- + 2H20 + 2H +.

  Seventh group (Nitrobacter spp.) - These nitrifying bacteria oxidize nitrite (NO2-N), a stable compound, still in nitrate (NO3-N), playing an important role in making food waste interesting as fertilizers. Just like Nitrosomonas, these bacteria actively operate at low and ordinary temperatures under one condition

  weak aerobic, as follows: 2NO2- + 02 -> 2NO3-.

Example II

  Joint culture of microbes on supports Supports such as sawdust, rice bran, peat, wood shavings and porous ceramic beads were sterilized and dried to have a water content of 10%. . On these supports were cultivated in joint culture the microbes which belong to the 7 groups of Example II. These bacteria carriers, sold under the trademark "Bio-Chip", were used to destroy food waste

  in a device which will be described in Example III.

Example III

  Device for destroying food waste at low and ordinary temperatures The present invention provides an optimal device in which the Bio-Chip, a support for bacteria on which various bacteria of Example I are cultivated in joint culture, can be used. Usually organic matter breaks down faster in an anaerobic condition than in an aerobic condition. For example, the speed of aerobic decomposition of organic materials is 7 times higher than the speed of anaerobic decomposition. With this in mind, the

  present invention used optional bacteria.

  In addition, since anaerobic fermentation produced a foul smelling gas, aerobic bacteria were also used. These bacteria are cultivated in joint culture on a support which is introduced into the

  device, together with food waste.

  The device of the invention will be described in

relationship with the attached drawings.

  Referring to Figure 1, there is a partial exploded perspective view of a device according to a

  first embodiment of the present invention.

  As shown in Figure 1, the device comprises a container 25 made of a thermally insulating material, a fermentation tank 18 with a waste chute 1 which is opened and closed by a cover 3 using a content of the type with spring 4, and deodorant means 5 with an exhaust pipe 6, the fermentation tank 18 and the deodorant means being installed inside the container. A hexagonal pin 21 which extends through the fermentation tank 18 is fixed to the fermentation tank by means of a support fixing adapter 9 and is connected directly to a rotary transmission 10 which rotates by energy of rotation transmitted via a chain 11 from an operational transmission 13 mounted in a motor 14. The voltage of

  the chain is controlled by a tension pulley 12.

  Figure 2 shows the device in rear perspective view. As shown in this figure, the fermentation tank 18 comprises a plurality of heating wires 29 on its surface to maintain the interior of the fermentation tank 18 at a predetermined temperature, for example 25 to 35 C. Six stirring fins, having each two auxiliary fins of cross section A, extend at angular intervals of 60 from a circumference of the axis 21 with a hexagonal cross section, as the

shows Figure 4.

  A second embodiment according to the present invention is shown in Figure 3. In this embodiment, an air supply system comprises a blower heater 299 and a blast air supply pipe 300 is disposed at instead of heating wires

29 in Figure 2.

  Referring to Figure 5, there is an enlarged view of a fermentation tank 18 of the second embodiment, in which a plurality of air inlets 301 connected to the supply air supply pipe 300 are established at a regular distance. At an upper site of the fermentation tank 18, an exhaust gas filter 2 is provided, from which the exhaust gas pipe 6 passes through the deodorant means to an outer surface in the rear side of the container. Exhaust gas, such as CO2, which is generated from food waste in the fermentation tank 18, passes from the exhaust gas filter 2, via the exhaust gas pipe 6, to the deodorant means 5 in which the offensive odors are eliminated by its neutralizing agent and a layer of activated carbon, and ventilated outside along the exhaust gas pipe 6. At another upper site of the fermentation tank 18 , an air inlet 8 equipped with a fan (not shown) is provided to supply a necessary quantity of air for the microbes inside the reservoir of

fermentation 18.

  As a variant, the deodorizing means 5 may comprise a honeycomb coated with platinum, in place of the neutralizing agent and the layer of activated carbon, in order to eliminate the foul odors generated by

food waste.

  Below will be given a detailed description

  the operation of the device. In order to use Bio-

  Chips of the invention, there is a need for a device for decomposing food waste, such as that shown in Figure 1. A minimum quantity of oxygen (air) is introduced inside the tank

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  of fermentation 18 so that food waste ferments quickly and without odor. From this point of view, Bio-Chips and food waste are mixed for as short a time as possible, to decompose food waste only with the air they contain. For example, a timer or gear operation can be used to continuously repeat a 30 minute cycle during which food waste and Bio-Chips are mixed for 5 minutes, followed by a 25 minute break . During the break, the decomposition of food waste takes place quickly by aerobic microbes. If the decomposition takes place only in the absence of oxygen molecules, very foul smells are produced. Thus, anaerobic fermentation is quickly induced just before the time when decomposition is completely converted to an anaerobic type, and then aerobic fermentation is caused by mixing food waste for 5 minutes through operation.

by timer or gear.

  Food waste can contain as much as 80-85% water. Water is slowly consumed while being absorbed in the environment of Bio-Chips, such as sawdust, peat, shavings

  of wood, porous ceramic beads, and the like.

  In the device of the present invention, the temperature of the fermentation tank is maintained at -35 C and can be brought to 40-45 C by the heat generated during the fermentation, consuming the water. The temperature inside the fermentation tank increases rapidly during fermentation, but is slowly decreased to low temperatures or

  ordinary (35 C or less) by means of a fan.

  Fermentation, which is a process in which microbes decompose organic materials, is divided into three types depending on the temperature: low temperature fermentation at 30 C or less; fermentation at medium temperature at 30-45 C; and fermentation at high temperature at 45-60 C. This fermentation at high temperature requires means to collect water because the fermentation takes place quickly. In addition, fermentation at high temperature forces organic materials to be rapidly broken down into acetate, CH4, C02 and / or H2S, producing significant odors. Thus, special deodorizing means are necessary for the fermentation at high temperature. On the contrary, fermentation at low or medium temperature does not produce acetate, which is significantly responsible for the foul smells generated during the fermentation of food waste. Certain odors, which are unavoidable, are completely eliminated by the means

  air fresheners 5 in the device.

  As mentioned, the acetate production process, its subsequent process (acetate -> CH4 + C02), and the H2S production process, are limited in the destruction device of the present invention. Thus, by virtue of this advantage of absence of odor, the device of the invention can be installed inside or outside dwellings or

catering establishments.

  In order to uniformly mix the Bio-Chips of the invention with food waste, a fin

  agitation extends from one side of the hexagonal axis 21.

  Thus, a stirring fin forms an angle of 60 with an additional adjacent fin. Auxiliary fins 20 having a cross section A are disposed on the stirring fins to facilitate mixing by the stirring fins. Auxiliary fins are also useful for stretching Bio-Chips

when reintroduced.

  Regarding the content of the spring type 4, it serves to dampen the significant weight of the cover 3, so as to absorb the shock which is provided to the fermentation tank by the cover 3. Thus, damage which may occur on the device when the cover 3

  is slammed is avoided by the grade 4.

  When the cover 3 is opened and closed, the mixing is automatically stopped and started, respectively. From this point of view, a limitation switch 7 of the spring projection type is disposed on a contact between the cover 3 and the fermentation tank 18 and

  connected to the electrical circuit for the mixing axis.

  When the lid is opened for the introduction of food waste into the fermentation tank, if the mixing continues to continue, an unpleasant scene is visualized and a foul odor is released. Therefore, it is preferable that the mixture

  be interrupted when the cover is open.

  To counter a drop in temperature inside the fermentation tank 18, the heating wires 29 or the fan heater 299 are mounted at the rear of the fermentation tank 18. For example, when it is cold, as in winter, the Heating wires or the fan heater work automatically to keep the inside of the fermentation tank at a temperature of 25 C or more. On the other hand, at a temperature above 35 C, only the fan of the fan heater 299 or a deodorizing fan (not shown) in the deodorizing means 5 is automatically actuated to lower the temperature of the

  fermentation tank 18 in a preferred range.

  In fermentation at low and ordinary temperatures according to the present invention, the odor which is generated during the fermentation of food waste is limited to as low a value as possible. However, like the smells that the food itself has

  are inevitable, the deodorizing means 5 are provided.

  The odorant gas inside the fermentation tank enters the exhaust gas filter 2 and circulates through the exhaust pipe 6 towards the deodorant means 5 at the level of which the odors are eliminated by the neutralizing agent and the layer of activated carbon, and the odorless gas is expelled through the exhaust pipe 6. Alternatively, an oxidizing system with platinum catalyst, in place of the neutralizing agent and the layer of activated carbon, can be used for

eliminate the odor.

  Optionally, a dashboard can be provided to detect the temperature and humidity of the fermentation tank, the target temperature and humidity and the practical temperature and humidity of the

platinum oxidizing catalyst.

Example IV

  Method for destroying food waste using the device A destruction device comprising a 700-liter fermentation tank was manufactured according to the

  description of Example 3. This device containing the

  carrier of bacteria, the Bio-Chips, was placed for 6 months, from June 24, 1996 to December 24, 1996, in a popular residential area in which there were 300 families. Food waste was introduced two or three times into the device, for a total amount of 100 kg per day. A fermentation cycle in which the food waste was mixed for 5 minutes, followed by a 25-minute break, was repeated, while the tank of

  fermentation was maintained at 25-35 C.

  During fermentation, a clean state was maintained with no foul odors, such as those

  attributed to H2S, CH4 and acetate.

  As described above, the device for destroying food waste can effectively ferment food waste at 25-35 C both in the presence and absence of oxygen molecules, so that food waste can be broken down quickly while that few odors are produced during fermentation. Therefore, the present invention is

  very useful in the environmental industry.

  The present invention has been described in an illustrative manner, and it should be understood that the terminology used is intended to be descriptive rather than limiting. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, we

  must understand that within the scope of the claims

  annexed, the invention may be put into practice other than in the manner which has been specifically

described.

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Claims (7)

  1. A method for destroying food waste at low and ordinary temperatures, characterized in that it comprises the steps of: joint culture of aerobic and optional active bacteria on sterile dry supports; introduction into a device containing the supports of a predetermined quantity of food waste per day for six months; and mixing of the supports with the food waste introduced, at regular intervals and at a temperature of 25 to 35 C, as a result of which the food waste is decomposed for 6 months by the action of fermentation and / or oxidation of bacteria on media. 2. Method according to claim 1, characterized in that the aerobic and optional bacteria are chosen from Aerobacter spp., Bacillus spp., Pseudomonas spp., Cellulomonas spp., Rhodopseudomonas spp., Nitrosomonas spp., Nitrobacter spp., And their combinations. 3. Method according to claim 1, characterized in that the sterile dry supports are chosen from the group consisting of sawdust, corn bran, peat, wood shavings, ceramic beads and their combinations.   4. Method according to claim 1, characterized in that the mixing step is carried out by repeating a mixing cycle in which the food waste and the supports are well stirred for 5   minutes, operations followed by a 25-minute break.   5. Device for destroying food waste at low and ordinary temperatures, characterized in that it comprises: a container (25) made of a thermally insulating material; a fermentation tank (18) with a waste chute (1) and a hexagonal axis (21), said waste chute being opened and closed by a cover (3) using a spring type content ( 4) so as not to shock said fermentation tank, said hexagonal axis extending through said fermentation tank and having six stirring fins on which are mounted two auxiliary fins (20) of cross section A, said fins d the stirring being arranged at an angle of 60 with additional adjacent fins and operating so as to mix the food waste, together with said auxiliary fins; and deodorizing means (5) with an exhaust pipe (6), said fermentation tank and said deodorizing means being installed inside said container, where said food waste can be completely decomposed while   producing little offensive odors.   6. Device according to claim 5, characterized in that said deodorizing means comprise a deodorizing system consisting of a neutralizing agent and a layer of activated carbon, or an oxidizing system with platinum catalyst in which a nest matrix of bees is coated with platinum.   7. Device according to claim 5, characterized in that said fermentation tank has an outer surface on which are mounted a plurality of heating wires (29) or in which are established a plurality of air inlets which are connected to a air supply system comprising a fan heater (299) and a supply air hose (300).