CA2542301A1 - Composting method and device - Google Patents

Abstract

The present invention relates to a composting device that incorporates high frequency vibration, preferably ultrasonic vibration.

Description

COMPOSTING METHOD AND DEVICE
FIELD OF INVENTION

[0001 ] The present invention relates to a method and device that enhances the efficiency of biological reactions, particularly the rate of production of compost, at both the domestic and industrial level.

BACKGROUND OF THE INVENTION

[0002] There is an ever-increasing demand to reduce the amount of waste that goes to landfill sites. The need to reduce waste is particularly pressing in densely populated areas. Many urban areas have introduced blue, grey and/or green boxes for recycling to try and address this need.

[0003] Composting is gaining popularity as a means of reducing or recycling organic waste. Composting is an appropriate way of handling various types of waste such as yard waste and kitchen waste. Materials such as grass clippings, leaves, twigs, fruits, vegetables, egg shells, grains and the like are all suitable for composting. It is estimated that between one-third and one-half of household waste can be composted. This would reduce the need to relocate as much garbage and also reduce the associated costs.

[0004] Composting devices typically comprise a receptacle for containing the waste material. Certain environmental factors are also required. These include moisture, air, warmth and certain bacteria or worms. For optimal results, the organic material must be kept damp and there must be sufficient airflow within the mass since oxygen is required for the process. Without a sufficient amount of air, an anaerobic process may take place that results in malodorous waste.

[0005] Waste is preferably digested to provide a welllgranulated compost material that is pleasant smelling. In order to expose as much of the material as possible to the air, it is necessary to occasionally mix the waste material.

[0006] United States Patent No. 6,855,527 describes a method of biotreating and recovering valuable metals from metal bearing refractory sulfide ore using a bioreactor. The process includes mixing the waste with coarse substrates, in particular rock. The rock is selected fro the group consisting of lava rock, gravel and barren rock containing carbonate minerals.

[0007] United States Patent No. 6,450,362 describes a compost bin that is basically a bendable circular wall that has closures at each sidewall to form a cylindrical compost device. The closure means make it easy to open the cylinder and mix the compost occasionally. When the cylinder is opened and the bin is removed from around the compost, the compost pile can be easily turned from all sides. No heavy lifting is required in order to move, rotate, or empty a compost filled bin.

[0008] United States Patent No. 6,576,462 describes another type of composting device that is a rectangular container. There is an opening door in the front panel. The door can be opened to extract compost or to stir the contents. The device also has a removable top, which has a reflective surface on one side and non-reflective surface on the other side.

[0009] United States Patent No. 6,029,918 discloses a kitchen waste composter. Vegetable matter is composed in an outer drum that can be rotated within an outer housing. By rotating the drum, the waste material is mixed for enhanced bioreactions.

[0010] United States Patent No. 5,730,524 is directed to a coupling device that interconnects the openings of two garbage cans like containers. When the connector is put on between the two garbage cans, the interiors of the two receptacles are in communication with each other. Waste material is deposited into one of the containers and then the connector and the second container are mounted on top. As the composting process proceeds, the material inside the receptacle can be mixed by inverting the system so that the waste moves from one receptacle to the other.

[0011] Many existing composting devices are labor intensive, mechanically complicated and/or do not produce a high enough compost production rate.
Particularly in urban areas, there may be a shortage of space to have multiple or large composters to increase the production rate. Thus there remained a need for a novel device and method to increase the rate of production of compost in a composting apparatus.

SUMMARY OF THE INVENTION

[0012] The present invention relates to bioreactors for the treatment of waste material. The waste is treated to increase the surface area available for reactions to take place and to increase the rate of reaction. While bioreactors that include means for mechanically mixing to increase surface area are known, the present invention works at a micro-level which leads to a much greater surface area. The present invention addresses the need to provide an improved bioreactor method and device.

[0013] In one aspect of the invention, an improved bioreactor for composting of waste material is provided.

[0014] A method of enhancing the rate of production of compost is also provided. The method comprises applying rapid vibration to waste in a compost receptacle. The rapid vibration is preferably, but not necessarily, achieved by ultrasonic vibration.

[0015] In one preferred embodiment the waste is suspended in a liquid medium and the ultrasonic waves are applied to the liquid.

[0016] In another embodiment, the ultrasonic waves are applied by a number of rods inserted into the interior of a waste receptacle.

[0017] In yet another embodiment, a stirring rod that stirs waste in a receptacle emits ultrasonic waves.

[0018] In another aspect of the invention, a bioreactor is provided. A
preferred bioreactor according to the invention is a composting device. The device comprises a bin for receiving waste material and a transducer for emitting ultrasonic waves.

[0019] The device of the present invention may be permanently installed or it may be portable.

[0020] This summary of the invention does not necessarily describe all features of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021 ] These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings wherein:

[0022] FIGURES 1A and B shows a compost device in accordance with one embodiment of the present invention;

[0023] FIGURES 2A and B shows a compost device in accordance with another embodiment of the invention;

[0024] FIGURES 3A and B shows yet another embodiment of a compost device of the present invention;

[0025] FIGURES 4A-C illustrate the effect of ultrasonic vibration on the decomposition of cabbage;

[0026] FIGURE 5 is a graphic comparison of the rate of decomposition of carrot with and without ultrasound; and [0027] FIGURE 6 illustrates the effect of ultrasound on decomposition of onion.

DETAILED DESCRIPTION

[0028] While composting is clearly an advantageous way to deal with waste, many people are reluctant to compost kitchen waste. This may be because current compost devices are often perceived as producing a rotting mass of foul smelling matter. The present invention addresses this problem by providing a method and device that increases the surface area of the waste so that more efficient biodegradation occurs. An efficient aerobic process results in a well-granulated compost that is odorless.

[0029] In the present invention rapid vibration is are applied to waste material in a receptacle. A preferred means of applying rapid vibration is through the use of ultrasound. However, for heavy equipment at the industrial level it may be difficult to apply sufficient ultrasonic vibration and other means of applying rapid vibration may be used. The present invention encompasses the use of all types of rapid vibration for the methods and devices. Although specific examples are provided for ultrasonic vibration, it should be understood that other types of rapid vibration may be used.

[0030] For ultrasonic vibration, the ultrasonic waves may be applied through a liquid medium, such as water in which the waste material is soaked. The receptacle is subject to the ultrasonic vibration. The receptacle is preferably made from a corrosion resistant material such as stainless steel, tiny hard materials such as wood chips, ceramics, glass or metal may be added to the liquid to enhance the effect. Preferably a decomposable material, such as wood chips, is used. This results in increasing the surface area that is exposed for composting activities.

[0031] Referring now to the Figures, Figures 1A and 1 B illustrate a rectangular shaped compost receptacle 10. The receptacle 10 comprises a base 12, four walls 14 and a top 16. It is shown containing waste material 20 and a liquid medium 22. A coarse material such as wood chips 24 may be dispersed within the waste material. In the illustrated embodiment an ultrasonic transducer 28 is mounted on the bottom of the compost receptacle.
The transducer applies ultrasonic rays to the compost receptacle and through the liquid medium and the waste material.

[0032] Ultrasonic waves can be applied as a pretreatment or during the composting period. In one embodiment the ultrasonic waves are applied by a number of pins or thin rods that can penetrate through the waste material deposited on the soil. The pins or rods are attached to a plate that provides the ultrasonic vibration. The pins may be permanently inserted into the material or they may be temporarily inserted and then removed after application of the waves.

[0033] In the embodiment shown in Figures 2A and 2B, a rectangular shaped composter is provided. The composter 30 comprises a receptable 32 and a lid 34. Waste material is put inside the receptacle of the compost device. An ultrasonic transducer 36 is associated with the lid of the composter. In this embodiment, a series of pins or rods 38 are associated with the transducer.
When the transducer 36 with the rods 38 is inserted into the waste material 40, ultra sonic vibration is applied along the rods to the waste material. In a preferred embodiment, the surface of the pins or rods may be grooved or etched to provide a scrubbing effect to the waste material.

[0034] In another embodiment the ultrasonic waves can be applied via stirring tools that are provided in the compost device. Stirring tools are sometimes provided in compost devices since mechanical mixing is known to be effective in accelerating decomposition. In devices and methods according to the present invention, various types of stirring tools or agitators are connected to a transducer to deliver ultrasonic waves to the waste material. It is clearly apparent that various types of configurations can be used to apply the ultrasonic waves to the waste material and that the invention is not limited to the specific examples given above.

[0035] Another embodiment of a compost system according to the present invention is illustrated in Figures 3A and 3B. The compost system includes a screw mechanism 52 that can be used to transport and/or mix waste. In this embodiment, an ultrasonic transducer 54 is operatively associated with the screw transporter or screw mixer. The surface of the screw threads may be grooved or otherwise roughened to provide an improved scrub effect on the waste material 56. As waste material flows through the screw mechanism, it is treated with ultrasonic vibration.

[0036] While simple types of compost devices have been described above for exemplary reasons, it is clearly apparent that the present invention encompasses any type of compost device that includes an ultrasonic inducer.
It is contemplated that any type of compost system can be adapted to a device of the invention including an ultrasonic transducer. Compost devices may be manufactured incorporating a transducer or existing devices may be modified by an "add-on" transducer. According to the present invention, an ultrasonic transducer can be applied to any configuration of composter device including large-scale industrial devices. Both large and small-scale devices are encompassed. This includes, for example, small kitchen units, units for multi-unit dwellings such as apartment houses, devices for treatment of food waste from institutions and restaurants and large-scale municipal or regional composting devices. In addition, while the ultrasonic device has been described primarily for use with a composting device, the method of the invention of applying ultrasonic vibration to waste material to increase the reactive surface can be applied to other applications. A compost device can be generally referred to as a bioreactor. According to the present invention, ultrasonic vibration is applied to any type of bioreactor to increase the rate of reaction. This may include bioremediation reactions, production of biofuels, treatment of sludge, etc.

[0037] A method of accelerating decomposition in a compost heap is provided. The method comprises providing a compost device having appropriate environmental factors such as soil, moisture, air, bacteria and/or worms, inserting waste material into the compost device and applying ultrasonic vibration to the device. The method of the present invention can be easily adapted to various types of composters currently on the market.

[0038] A single transducer can be used for a maximum effect. For industrial scale composting, it may be desirable to have more than one transducer. If more than one transducer is used, they should produce a constructive wave.
The position of the transducer can be varied without altering the effectiveness of the method.

[0039] Good results can be obtained using a wide range of frequencies. For optimal results, a strong ultrasonic field is required and the energy produced by the transducers is transmitted into the liquid containing waste material.
Ultrasonic waves having a frequency from about 1 to about 10,000 kHz can be used in the method and device of the present invention. More preferably about 25 to 500 kHz waves are used.

[0040] The effect of ultrasonic vibration on the rate of decomposition was assessed using various types of vegetable matter. Specific methods are discussed in the Examples below. The rate of decomposition can be determined by analyzing the weight of the waste material. As waste is decomposed and water and gas are formed, the weight of the waste is decreased. Application of ultrasonic vibration significantly increased the rate of decomposition as compared to non-treated waste. The ultrasonic treatment is particularly effective at the early stages of decomposition. By accelerating the rate of decomposition, more waste can be processed in a shorter time. This provides significant benefits at both the household and industrial level. As shown in Figures 4A, B, and C and discussed further in the examples below, cabbage is decomposed at a significantly faster rate in the presence of ultrasonic vibration. Figure 4A illustrates that the total weight decreases more rapidly in the sample treated with ultrasonic vibration. The effect is especially important at the early stages as shown in Figure 4B.
Figure 4C illustrates the decrease in terms of % weight loss. The untreated sample takes 36 hours longer to reach the same stage. These results indicate that applying ultrasonic waves significantly increases the rate of production of compost. Thus, more waste can be processed in a shorter time.

[0041 ] The rates of production of compost from the decomposition of carrot (Figure 5) and onion (Figure 6) are also significantly enhanced by ultrasonic treatment. The results demonstrate that the method can be applied to various types of organic material and the efficiency of composting can be significantly increased by the methods of the present invention.

[0042] The above disclosure generally describes the present invention. It is believed that one of ordinary skill in the art can, using the preceding description, make and use the compositions and practice the methods of the present invention. A more complete understanding can be obtained by reference to the following specific examples. These examples are described solely to illustrate preferred embodiments of the present invention and are not intended to limit the scope of the invention. Changes in form and substitution of equivalents are contemplated as circumstances may suggest or render expedient. Other generic configurations will be apparent to one skilled in the art. Documents such as patents or patent applications referred to herein are hereby incorporated by reference.

EXAMPLES
[0043] Although specific terms have been used in these examples, such terms are intended in a descriptive sense and not for purposes of limitation.
Methods of microbiology and physics referred to but not explicitly described in the disclosure and these examples are reported in the scientific literature and are well known to those skilled in the art.

Example 1. Controlled composting of cabbage [0044] A cabbage was cut into strings and divided in two. The control (A) was placed in lukewarm water. The treated half (B) was placed in an ultrasonic bath for one hour. The samples were then placed in sealed plastic bags along with moist soil. The starting amounts were as follows:

A (g) B (g) (reference) (ultrasonic) cabbage (g) Original 10.397 10.425 soaked with water for 1 hour 11.370 11.560 Soil (g) original, non-dry 157.709 157.420 total (g) 169.079 168.980 [0045] The samples were inspected and weighed at various time points and the percent weight loss was recorded. The results are shown below:

time elapsed weight loss %
Memo A (g) B (g) (h:m:s) A B
0:00:00 169.079 168.980 0.000 0.000 58:40:00 168.955 168.760 0.073 0.130 134:00:00 bag opened 168.701 168.452 0.224 0.312 160:00:00 bag opened 168.571 168.351 0.300 0.372 227:00:00 bag opened & shaken up 168.242 168.023 0.495 0.566 279:30:00 bag opened & shaken up 167.970 167.725 0.656 0.743 447:50:00 bag opened & shaken up 167.583 167.312 0.885 0.987 i i .

514:00:00 bag opened 167.426 167.156 0.978 1.079 [0046] The percent weight loss correlates with decomposition as the vegetable matter is transformed into compost, methane and water. In the first three days, the majority of the cabbage was decomposed.

[0047] Since vegetables comprise mainly water (>90%), a weight decrease of about 1% is a significant indicator of the decomposition rate. As shown in Figures 4A, 4B and 4C, the majority of the decomposition occurs in the first few days with the ultrasound treated sample having an accelerated rate of decomposition.

Example 2. Controlled decomposition of carrot [0048] Carrots were cut into strings and divided into two samples. One sample (A = control) was placed in lukewarm water for one hour. The second sample (B = experimental) was placed in a 35kHz ultrasonic bath for one hour. The samples were then placed in separate sealed plastic bags together with moist soil. The samples were stored at 30'C. The starting amounts were as follows:

A (g) B (g) (reference) (ultrasonic) Carrot (g) Original 20.354 20.129 soaked with water for 1 hour 20.394 20.232 Soil (g) original, non-dry 167.426 167.156 total (g) 187.144 186.866 [0049] The samples were examined and the amount of weight loss was measured at various times. The results are shown below:

time elapsed Memo A(g) B(g) weight loss %
(h:m:s) A B
0:00:00 carrot inserted, well shaken 187.144 186.866 0.000 0.000 21:26:00 186.944 186.643 0.107 0.119 67:40:00 186.152 185.791 0.530 0.575 95:59:00 185.826 185.298 0.704 0.839 119:28:00 A: still identifiable 185.435 184.814 0.913 1.098 B: mostly gone 167:33:00 A: mold, very wet (clay) 185.082 184.328 1.102 1.358 B: no mold, almost all gone 226:55:00 A: still identifiable 184.771 183.890 1.268 1.593 B: hard to identify [0050] The results are shown graphically in Figure 5. It is clearly apparent that the rate of decomposition is accelerated in the ultrasonic treated sample.
Example 3. Controlled decomposition of onion [0051] The onion was cut into thin slices and the segments separated. The onion was divided into two samples. The first "control" sample (A) was placed in lukewarm water for an hour. The second "experimental" sample was put in an ultrasonic bath for one hour. Each sample was then placed in a sealed plastic bag along with some moist soil. The starting concentrations were:

p- (g) B (g) (reference) (ultrasonic) Onion (g) Original 20.470 20.174 soaked with water for 1 hour 20.179 20.202 soil (g) original, non-dry 159.946 159.979 total (g) 179.933 180.020 [0052] The samples were examined and the weight was recorded as various times. The results are shown below:

time elapsed weight loss %
(h:m:s) memo A(g) B (g) A B
0:00:00 onion inserted, well shaken 179.933 180.020 0.000 0.000 21:35:00 179.751 179.806 0.101 0.119 67:40:00 179.248 179.228 0.381 0.440 96:06:00 178.917 178.868 0.565 0.640 119:29:00 A: white, identifiable 178.553 178.494 0.767 0.848 B: small, separated 167:40:00 A: mold, some left 178.232 178.091 0.945 1.072 B: no mold, All gone 179:00:00 A: still some identifiable 177.905 177.778 1.127 1.245 B: not identifiable [0053] The results are shown graphically in Figure 6. As can be seen from the diverging lines, the rate of decomposition is accelerated in the sample pretreated with ultrasound.

[0054] The present invention has been described with regard to one or more embodiments. However, it will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims.

Claims (15)

1. A method of accelerating a reaction in organic waste material, said method comprising applying rapid vibration to the waste material.

2. A method according to claim 1, wherein the rapid vibration is ultrasonic vibration.

3. A method according to claim 2 wherein ultrasonic waves have a frequency from about 1 to about 10,000 kHz.

4. A method according to claim 3 wherein the frequency is from about 25 to about 1000 kHz.

5. A method according to claim 4 wherein the frequency is from about 25 to 500 kHz.

6. A method according to claim 1 wherein said ultrasonic waves are applied to organic waste in a compost device.

7. A method according to claim 1 wherein said ultrasonic waves are supplied via a plurality of rods inserted into the waste.

8. A method according to claim 6 wherein ultrasonic vibration is applied to liquid in the compost device.

9. A method according to claim 6 wherein the ultrasonic waves are applied via a stirring tool.

10.A bioreactor comprising a waste receptacle and an ultrasonic transducer.

11.A bioreactor according to claim 10 comprising a composting device.

12.A bioreactor according to claim 10 wherein the ultrasonic transducer is associated with a wall.

13.A bioreactor according to claim 10 wherein the transducer is associated with a stirring tool.

14.A bioreactor according to claim 10 wherein the transducer is associated with a rod.

15.A bioreactor according to claim 10 comprising a biofuel generator.