WO1993001149A1

WO1993001149A1 - A composting method, composting apparatus and method and apparatus for delivering microwave energy to layered material

Info

Publication number: WO1993001149A1
Application number: PCT/SE1992/000499
Authority: WO
Inventors: Bror Ivar HULTSTRÖM; Lars Håkan HULTSTRÖM; Bo Göran HULTSTRÖM
Original assignee: Hultstroem Bror Ivar; Hultstroem Lars Haakan; Hultstroem Bo Goeran
Priority date: 1991-07-02
Filing date: 1992-07-02
Publication date: 1993-01-21
Also published as: CA2112662A1; SE9102062D0; EP0592545A1

Abstract

A composting method in which decomposable material, such as industrial waste, night soil and kitchen waste, is converted in a bed to mull in a mold-producing process with the aid of microorganisms. The method is mainly characterized in that the bed of decomposable material is heated, when necessary, by means of microwave energy in order to adjust the working temperature of the bed as a stage in controlling the mold-producing process so as to obtain a desired mold-producing rate and/or a desired final product. The invention also relates to a composting plant and to a method and an arrangement for delivering microwave energy to layered composting material.

Description

A Composting Method. Composting Apparatus and Method and Apparatus for Delivering Microwave Energy to Layered Material

Ihe present invention relates to a composting method by means of which decomposable material, such as industrial waste, night soil and kitchen waste is converted to mull in a moldering process with the aid of microorganisms.

The invention also relates to cσnposting plants.

In addition, the invention relates to a method and to apparatus fo livering microwave energy to layered material.

This type of cαmposting is essentially known. In order for the pro to be optimal, both the temperature of the bed and its moisture co should be maintained within given limits. When the temperature or moisture content of the bed is too low, the microorganisms will ce to grow. Conversely, when the temperature of the bed is too high, about 60°C, it is probable, in some cases, that the microorganisms will die. Problems concerning the delivery of air to the bed arise when the bed is too moist. Dirty liquid running from the compostin container can also create problems. On the other hand, a hard oute skin or crust forms readily when the bed dries out.

It will be understood from this that there is a need of a process apparatus which will enable temperature and moisture content to be kept at an optimal level. Many attempts have been made to insulate the container, to introduce agitators, heating elements, and the like, although none of these attempts has been truly successful.

Ihe present invention relates to a method and to apparatus which solve the aforesaid problems. Heating is effected directly within bed, preferably in the water present in the material. Heating with microwave energy can thereby ensure that the major part of the ene will be delivered to the wettest part of the bed. Ihe moisture con of the bed will, in this way, be redistributed throughout the whol of the bed treated. The method also enables the bed to be kept por without the formation of a skin or crust which would slow down th molding process.

Ihe invention also relates to a composting method with which decα posable material, such as industrial waste, night soil and kitch waste is converted in a bed to mull in a molding process with the of microorganisms.

Ihe method is mainly characterized by heating the bed composed of decomposable material when necessary by means of microwave energy the purpose of adjusting the working temperature of the bed as a stage in controlling the molding process in a manner to achieve th desired molding rate and/or the desired final product.

The invention also relates to a composting apparatus for convertin decomposable material, such as industrial waste, night soil and kitchen waste to mull in a molding process by means of microorgani

The apparatus is mainly characterized by devices which, when neces function to heat the bed composed of the decomposable material by means of microwave energy so as to adjust the working temperature the bed as a stage in controlling the molding process in a mariner achieve the desired molding rate and/or final product.

The invention also relates to a method of delivering microwave ene and preferably also air to layered decomposable material.

This method is specially characterized by delivering microwave ene a d preferably also air to layered material through gratings or gr which support the layered material.

The invention also relates to apparatus for delivering microwave e and preferably also air to layered decomposable material.

The apparatus is specially characterized by gratings or grids rtiic support the layered material and which also function to deliver microwave energy and preferably also air to said layered material. Ihe invention will now be described in more detail with reference exemplifying embodiments thereof and also with reference to the accompanying drawings, in which

- Figure 1 is a schematic, vertical section view of a first emb ment of a cαπposting apparatus in the form of a mold-producin toilet with which the concept of the invention is applied; Figure 2 is a schematic illustration of a mold-producing toil heated by microwave energy; - Figure 3 is a block schematic of a microwave system;

- Figure 4 is a simplified illustration of a halfwave voltage doubler circuit;

Figure 5 is a simplified illustration of a fullwave voltage doubler circuit; - Figure 6 is a simplified illustration of power control;

Figure 7 illustrates a first embodiment of a measuring system intended for controlling temperature and moisture content; Figure 8 illustrates schematically another embodiment of com¬ posting apparatus in the form of a water-flushing system inte for cσπposting and microwave heating in accordance with the invention;

Figure 9 is a schematic, vertical sectioned view of a third embodiment of the inventive composting plant; Figure 10 illustrates part of the plant shown in Figure 9 as obliquely from the left in said Figure;

Figure 11 is a schematic cross-sectional view which illustrat two levels of grates, each of which is intended to support a respective layer of decomposable material with the aid of tub elements, and also to deliver microwave energy; - Figure 12 illustrates schematically grates vrtiich are supplied directly with microwave energy, said grates being shown trans versely to the direction of their longitudinal axes; and Figure 13 illustrates schematically grates which are supplied microwave energy indirectly, said grates being seen in the sa view as that of Figure 12.

Figure 1 illustrates an embodiment of a mold-producing toilet whic includes a container 1 to which night soil 3 and optionally also kitchen waste and garden waste is delivered through a toilet 2 or like. The reference numeral 4 identifies a bed which includes mul like material. In the illustrated case, the bed also includes an upper layer 5 of garden soil. The bed 3, 4 is constructed on a sl surface 7 which is inclined towards a container-errptying flap or 6 and which includes downwardly open grate-like devices 8 through which air is delivered to the bed from a separate air intake 9. Extending from the container 1 is a ventilating pipe 10 through w air, water vapour (steam) and other gases are intended to depart. plant also includes a suction fan 11 for the withdrawal of air an gases, thereby creating a sutpressure in the container. As shown i Figure 2, the inventive plant also includes devices 12 whereby the bed 4 and the material 3 supplied thereto can be heated with micrc energy when required, so as to adjust the working temperature of t bed 3, 4 as a stage in steering the mold-producing process to a desired mold-producing rate and/or a desired final product. The te bed 3,4, as used here, is meant to include both the mull bed, etc. the material delivered thereto. In the present case, the container includes a casing 13 which prevents microwaves from spreading from the interior of the container to the surroundings, such as a metal casing 13, for instance. In the present case, the casing 13 is constructed to form a microwave cavity, preferably a cavity of the ultimode type. The cavity is preferably given a configuration so that the bed will be heated as homogeneously as possible.

According to one preferred embodiment, the container is lined inte ally with a corrosion-resistant layer 14, ccmprised, for instance, a plastic, rubber material or seme equivalent material whose diele properties are such that the layer will not be heated or at least heated to any significant extent, by microwaves.

The invention is suitable, among other things, for aerobic bacteri strains which require oxygen in order to function and also anaerob bacteria strains which will function only in the absence of oxygen.

In the aerobic process, the carbon present in the biological mater is combined with the oxygen contained in the air so as to form car dioxide. In many cases, the optimum temperature lies around 40°C an the material shall be roughly as wet as a bath sponge from which t water has newly been squeezed.

In the case of the anaerobic process, where no oxygen is present, methane gas is formed instead. In this case, the optimum temperatu is normally higher, about 60°C, and it is important also in this c that the level of the moisture content of the bed is the correct l

It is preferred in many cases to adapt or control the bed temperat with respect to those microorganisms which provide the best rate o decomposition, at each stage of the mold-producing process.

The aerobic process is applicable in the case of a mold-producing toilet in which it moist be necessary to be able to open flaps or doors, Figures 1 and 2, and endeavours to improve the supply of oxygen have been made by blowing air into the bed through gill-lik devices or equivalent devices. Ihe anaerobic process may be applic in other contexts, for example in water-flushing systems, Figure 8. It is conceivable to give such systems a more comprehensive design with a plurality of toilets connected to one and the same containe Ihe methane gas generated can be collected and used as fuel.

As illustrated in Figure 2, at least one microwave generator 12, preferably in the form of a magnetron, is connected to the contain 1 either directly or through the intermediary of a waveguide 15, having the form, for instance, of a metallic tube 16 of specific dimensions.

Figure 3 illustrates schematically a system for generating microwa energy which includes a system control unit 17, a power unit 18 wh is intended to power the microwave generator 12 which, in turn, is connected to an applicator, in this case to the container 1. The r values 19 are intended to be measured in the proximity of the cont 1 and are applied to the control unit 17 for comparison with the s point values, this comparison forming the basis on which the power unit, and therewith the generator, is controlled. Microwaves, such those used in microwave ovens for domestic use and which are also suitable for heating purposes in the illustrated case, work with t frequency 2450 MHz, which corresponds to a wave length in air of about 12.25 cm.

The embodiments of the power unit, halfwave voltage doubler circu and fullwave voltage doubler circuit respectively, illustrated in

Figures 4 and 5, include a high voltage transformer 20. Other typ stabilizing means for avoiding variations in microwave power as a result of variations in voltage supply are also conceivable.

The embodiments illustrated in Figures 4 and 5 also include heatin coil or winding 21, a capacitor 22, a diode 23 and a magnetron 24. These power unit variants have a good stabilizing effect within a given range of mains voltage and are very reliable in operation.

According to one embodiment, Figure 6, the power unit, Figures 4 a 5, for supplying the microwave generator is power-controlled by a and-frσm control means, wherein devices 25, a power-control unit, provided for holding the unit active over a predetermined number o mains periods and non-active over a predetermined number of mains periods, and wherein thyristors or so-called triacs 26 are prefera provided for switching the unit on and off, the illustrated embodi including a fullwave voltage doubler circuit by way of example.

According to one embodiment, the means for controlling the generat of microwaves is designed to reduce the active time of the microwa generator provided, for instance with the aid of a thermostat (not shown) having a so-called dead zone.

The control unit 17, Figure 7, is intended to adjust the mean tem- perature of the bed on the basis of real values 19 and set-point values 19', so as to maintain a predetermined ideal temperature, i the case of an aerobic process a temperature of about 40°C for instance, and to limit the maximum temperature in the bed so as no to exceed a predetermined value, in the case of an aerobic process temperature of about 60°C, for instance. The system includes at le one thermoelement 27 for measuring bed temperature, vάierein sensor 28 and conductors 29 of said element are screened from microwaves means of metallic devices (not shown) in some suitable manner so a to achieve correct measurements that are undisturbed by the micro Similar to Figure 3, Figure 7 illustrats a relatively general pla according to the invention, in vΛiich power unit and power control be constructed in accordance with Figures 4-6, for instance.

According to one embodiment of the invention, devices 30 of some suitable kind are provided for indirect measurement of the moistu content of the bed by measuring the humidity of the exiting air, wherein the measuring location is placed outside the container 1, namely in the ventilation pipe, or duct, in the illustrated case. According to one embodiment, the control unit is intended to brin heating of the bed to a stop and, when appropriate, to cause wate be delivered to the bed when the moisture content of the bed, i.e. this case the humidity of the exiting air, falls beneath a given value. Although the bed -temperature will fall when water is added, therewith retarding the process, the bed will be prevented from drying out. Heating of the bed is continued when the moisture con again increases, thereby accelerating the process. According to preferred embodiments of the invention, the moisture content, or i other words the dry solids content of the bed, is controlled by redistribution of water in the bed, evaporation of water from the or the supply of water to the bed, or by combinations of these fe as a stage in steering the mold-producing process to a desired mol producing rate and/or a desired final product.

For safety reasons, such openings as the emptying flap or door 6 a the toilet opening 2, and also container seams and ventilation pi etc., are constructed so that microwaves are unable to leak out. These seals against microwaves can be achieved with a fine-mesh metallic net 31 or some like material, as illustrated in Figure 2. Although not shown, it is preferred to provide devices vftiich will interrupt the generation of microwaves when the toilet lid 32 is lifted. Examples of seams, are found in so-called chokes, such as those fitted to the doors of domestic microwave ovens and in waveg flanges.

In the water-closet or water-flushing plant illustrated in Figure solid waste, etc. , is separated from flushing liquid and urine and these liquids are passed preferably to a BDT-sewage pipe via a UV- filter. In order for the mold-producing process, such as an anaero process, to function satisfactorily, it may be necessary to add a given quantity of nitrogen, in the form of nitrogen compounds, to process system.

The plant illustrated in Figures 9 and 10 includes a rotatable or oscillatable container 1 of generally cylindrical shape, for instan with which decomposition, or cc posting, of the material is intende to take place continuously or almost continuously. As indicated by arrows 33, material is delivered to the container 1 at one end 34 thereof while bed material which is assumed to have decomposed to a mold is removed at the other end 35 thereof, the container being disposed so that the bed is fed towards said other end 35.

According to the illustrated emtodiment, the container is intended maintain a given angle of inclination so as to facilitate forward feeding of the bed. In the case of the illustrated embodiment, feed 36, e.g. at leasst in the form of an essentially helical or screw- like flanged element, are provided for achieving at least partial forward feeding of the bed. The flanged element may for instance be sealingly mounted at the inner wall of the container such as to prevent liquid from ininning along the container bottom 37, i.e. the container part that temporarily constitutes the lower part. The feeders 36 also have a mixing effect. Naturally, it is conceivable provide more than one flanged element, in which case the flanged elements will extend mutually parallel in a screw-like configuratio for instance.

The container 1 may, of course, be rotated or oscillated in several ways. In the case of the illustrated embodiment, an electric motor acts on the container with the container journalled on supports 39, as shown schematically in Figure 2.

AcαDrding to the illustrated embodiment, the rσtatably mounted con¬ tainer is heated with microwaves that are produced fcy a microwave generator 12, such as a so-called magnetron, which is located exter ally of the container, wherein a waveguide 40, for instance in the form of a metallic tube of specific dimensions, is provided for introducing the microwaves into the container and wherein outlets a preferably provided in the waveguide for the purpose of distributin microwave energy within the container.

The illustrated, rotatably mounted container is housed in a housing which may be made of metal sheet for instance, into rtiich material be composted is delivered through a tube 42 which passes into the container, and is removed from the container through a flap or door 43. Means 44 are provided for collecting and removing liquid that h left the container.

As illustrated in Figure 10, the container includes means, such as perforations 45, for removing surplus liquid from the container. Th housing, or encapsulation, is also intended to remove water vapour and, when applicable, other gases that are formed during the compos process, as illustrated ty way of a chimney 47 provided with a fan

The frequency at which the container is rotated or oscillated and t time taken for the material to pass through the container are adapt to the cαrrposting process concerned. In many instances, it may be appropriate to rotate or oscillate the container through one turn each calendar day and the material throughflow time to be from two more weeks.

Openings that are present in the apparatus illustrated in Figures 9 10, such as the flap or door 43, are constructed so that microwaves unable to leak out. This feature has been earlier discussed.

As with the earlier embodiments, the embodiment according to Figure 9 and 10 includes devices 17, 27, 30 for measuring bed temperature and bed moisture content, either directly or indirectly, and for controlling the operating temperature of the bed and preferably the moisture content of the bed. These devices have not been shown in Figures 9 and 10.

Embodiments are also conceivable in which the composting process is intended to take place batchwise, wherein a rotatable or oscillatab container, or an agitator, not shown, is provided and wherein the material is delivered and removed batchwise, and wherein, when an agitator is provided, the container may be stationary or moveable. The process is controlled and the microwave energy delivered, etc. in the same manner as that earlier described.

Although not shown, certain embodiments of the invention include devices for measuring the amount of carbon dioxide exiting from t bed, wherein this emission of carbon dioxide is used as a measure of the rate at which mold is produced and as a basis for controll the delivery of air to the bed. Although not shown, other embodime are conceivable in which devices are provided for measuring and controlling the flow of air through the bed as a stage in controll the mold-producing process towards a desired mold-producing rate and/or a desired final product.

In same cases, it is preferred to layer the material in the bed, a shown at 48 in Figures 11-13, with each layer having a given large thickness, such as a thickness of about 200 mm, so as to ensure th the microwaves will penetrate to an effective depth. The term laye and layered, as used here, shall be given a wide interpretation, a these terms are intended to cover all conceivable possibilities fr a continuous, integral layer of material to material in the form o more or less densely-packed entities. To this end, the embodiment illustrated in Figures 11-13 includes grates or grids 49 which for supports for layers of material 48 and, at the same time, form mea for supplying microwave energy and, preferably, means for supplyin air to the bed, said grates, when appropriate, also forming wavegu for the microwaves. According to one embodiment, the grates includ elongated mutually adjacent and preferably at least generally mutu parallel elements 50, 51 which are intended to support a layer of the material to be composted and to guide and emit microwave energ and, when appropriate, to guide and emit air. The grates may be comprised of waveguides 50 having a rectangular cross-section, or some other cross-section, Figures 11 and 12, through which microwa can be guided. By suitable configuration of the waveguides, the waveguides are able to emit microwave energy, for instance through appropriately shaped and positioned slots (not shown) to layers 11 located beneath and/or above the grate arrangement. The waveguides may have the form of metallic tubes or of rods of a dielectric mate which will not be heated by micrcwave energy delivered from one or more microwave generators, Figure 11, or which will only be heated an insignificant extent, or which in certain cases may be construct in a manner such that each separate waveguide 51 will absorbe micro energy present in the container and then retransmit microwave energ in the aforedescribed manner. This arrangement is also called a secondary antenna arrangement.

Figures 11-13 illustrate a construction in which grates are arrange on at least two different levels. In this case, the grates can be arranged to deliver microwave energy and preferably air to an under ing layer of material. According to one embodiment, which is prefer in some cases, the arrangement may include several levels of elemen and layers, wherein the distance between the layers is adapted so that microwave energy can be delivered to the layers from two sides thereof, among other things.

The inventive method and the manner in which the inventive composti plant operates will be understood in all essentials from the above. bed is heated fcy means of microwaves and the container 1 is constru to form a microwave applicator, with the intention of maintaining a high mold-producing rate.

The advantages afforded by the invention in comparison with known techniques will also have been understood from the aforegoing. Thus heat is developed immediately within the bed material, thereby avoi a high surface temperature which would result in drying of the oute layers of the bed. The microwave power can be controlled in respons to the temperature and the moisture content of the bed material, so as to retain ideal conditions throughout the whole of the bed. As a result of the conditions favourable to decomposition of the materia the bed will be smaller than in known plants which lack a microwave heating facility, and consequently the container may be smaller tha the containers of said comparable plants.

In the case of plants in which the container can be rotated so as t 12 achieve continuous decomposition of the material, the bed is turn continuously, thereby guaranteeing, among other things, that an effective amount of oxygen will be supplied. Because the bed mate is constantly moved forwards, waste materials which have reached different stages of molding will not be intermixed, and because t mold-producing plant, or composting plant, is automatic, only the minimum inspection is necessary and because the bed is rotated an fed forwards along the cylinder, the ∞ntainer, the bed can be di into a layer of effective thickness adapted to the mold-producing process concerned.

The invention has been described in the aforegoing with reference exemplifying embodiments thereof. It will be understood, however, other embodiments and minor changes are conceivable without depa from the scope of the inventive concept.

For example, according to one preferred embodiment, the container of a mold-producing toilet is constructed from two generally ident halves l¹. According to one embodiment, which is preferred in cert instances, the container is comprised of plastic-coated metal shee such as aluminium sheet. In this regard, an internal plastic layer can be provided when forming the cylinder.

In the case of the embodiment illustrated in Figures 9 and 10, the container 1 is preferably comprised of plastic-coated metal sheet, thereby enabling the container to be used safely without being enc sulated in an external metal housing, when the container is sealed against the leakage of microwaves. The container may also be compr of a plastic material or some other material which does not screen microwaves, in which case an encapsulating metallic housing is re¬ quired. Thus, in certain instances, the opening through whic the material is discharged from the container 1 shall be sealed agains the leakage of microwaves at said discharge end 35. This can be achieved in several ways, for instance with the aid of a so-called cell feeder of the carrousel door type, not shown.

With regard to the delivery of microwave energy in the embodiment lustrated in Figures 9 and 10, this can also be effected at the en 13 walls of the container in a manner not shown, wherein one or more microwave generators, magnetrons, are arranged at said end-walls f supplying microwaves to the bed directly, in which case the microw are not distributed through the medium of waveguides extending in container.

Two applications of the invention have been described in the afore ing, namely one application with mold-producing toilets in which night soil and optionally kitchen waste and garden waste is delive to the plant for decomposition into compost, and one application f continuous composting processes, primarily intended for composting a larger scale industrial waste, e.g. waste that derives from ex¬ perimental industrial kitchens, waste from the production of food¬ stuffs, etc. Several more applications are, of course, conceivable. One such application concerns a microwave-heated composting contai for single-family or multi-family use, intended for composting kitc waste, garden waste, etc. There is nothing to prevent continuous plants, Figures 9 and 10, from being used for toilet use and singl family or multi-family buildings, or for industrial waste to be composted batchwise, i.e. non-continuously.

The invention is thus not restricted to the aforedescribed and il¬ lustrated embodiments thereof, since modifications and variations c be made within the scope of the attached Claims.

Claims

1. A composting method in which decomposable material, such as industrial waste, night soil and kitchen waste, is converted to mul in a compost bed by means of a mold-producing process effected wit the aid of microorganisms, char a c t er i z e d fcy heating t bed (3, 4) containing waste material (3) when required fcy means of microwave energy, for the purpose of controlling the working tem- perature of the bed as a stage in guiding the mold-producing proces to a desired mold-producing rate and/or a desired final product.

2. A method according to Claim 1, ch a r a c t e r i z e d in the moisture content of the bed is controlled by redistributing wat in the bed, evaporating water from the bed or supplying water to th bed, or combinations hereof, as a stage of controlling the mold- producing process to a desired mold-producing rate and/or a desired final product.

3. A method according to Claims l or 2, char a ct er i z e fcy controlling the flow of air through the bed as a stage in contro ling the mold-producing process to a desired mold-producing rate and/or final product.

4. A method according to Claims 1, 2 or 3, char a c t er i z e d by measuring the carbon dioxide emitted from the bed and using measured value as an indication of the mold-producing rate and, whe appropriate, for adjusting the supply of air to the bed.

5. A method according to Claims 1, 2, 3 or 4, ch ar a ct er i z e d fcy encapsulating the container (1) in a housing (13) which functions to prevent spreading of microwaves from the container interior to the surroundings, said housing having the form of a metallic casing (13) , for instance.

6. A method according to Claim 5, c h a r a c t e r i z e d by lining a container (1) for the bed (3,4) internally with a corrosio resistant layer (14) , for instance a layer of plastic, rubber or sce other material having dielectric properties such as not to be heated by the microwaves, or not heated to any significant extent.

7. A method according to Claims 1, 2, 3, 4, 5 or 6, c h a r a c - t e r i z ed by connecting at least one microwave generator (12) t a container (1) for the bed (3,4) directly car through the medium of waveguide (15, 40), for instance in the form of a tube (16, 40) of specific dimensions.

8. A method according to Claims 1, 2, 3, 4, 5, 6 or 7, c h a ¬ r a ct e r i z ed fcy effecting the control process in a manner to reduce the neoesary active period of the microwave generator (12) , f instance with the aid of a thermostat having a dead zone.

9. A method according to Claims 1, 2, 3, 4, 5, 6, 7 or 8, cha ¬ r a c t er i z ed by adjusting the bed temperature with regard to those microorganisms which will provide the best decomposition rate at each stage of the process.

10. A method according to Claims 1, 2, 3, 4, 5, 6, 7, 8 car 9, chara ct er i z ed fcy adjusting the average bed tenperature as to maintain a predetermined ideal temperature of, for instance, about 40°C in the case of an aerobic process and so that the maximum bed temperature will not exceed a predetermined value, for instance about 60°C in the case of an aerobic process.

11. A method according to Claims 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, ch a r a ct er i z ed by sustaining an anaerobic process.

12. A method according to Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, chara cter i z ed fcy interrupting heating of the bed and, when applicable, delivering liquid to the bed vΛien the bed moisture content falls belcw a predetermined value.

13. A method according to any one of the preceding Claims, cha ¬ r a c t er i z ed fcy sealing the openings present in a bed contain against microwaves with the aid of a fine-mesh metal net (31) or equivalent means.

14. A method according to any one of the preceding Claims, cha r act er i z e d by connecting existing lids (32) and flaps (45 with switch means which function to switch-off the micrcwave unit vdien said lid or said flap is opened.

15. A method according to Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 12, 13 or 14, ch a r a ct e r i z e d fcy carrying out the compo ting process batchwise, using a rotating or oscillating container o agitator and delivering the material to the bed and removing the material from the bed batchwise.

16. A method according to Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 12, 13 or 14, ch a r a c t e r i z e d by carrying cut the compo ting process generally continuously in a rotating or oscillating container (1) and by supplying material (3) to the bed in the vicin of one container end (34) and removing said material frcm the bed i the proximity of the other container end (35) , and by advancing the bed towards said other end.

17. A method according to Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16, characteri zed by removing surpl liquid from the bed, for instance through perforations (45) in the container.

18. A method according to Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17, characteri z ed by layering t bed material, said layers having a given largest thickness, for instance a thickness of about 200 mm.

19. A method according to any one of the preceding Claims, char acter i z ed by layering said bed material with the aid of grates v ch, at the same time, form layer supports and means for delivering and distributing microwave energy and, preferably, also a air supply means.

20. A method according to Claims 18 or 19, character¬ i z ed fcy spacing apart the material layers in a plant which inclu several layers so that microwave energy can be delivered from two sides of respective layers.

21. A composting plant for converting decomposable material, such industrial waste, night soil and kitchen waste, to a mull in a mold-producing process with the aid of microorganisms, c h a r a t e r i z e d by means (12) for heating the bed (4) of decαπposabl material (3) when necessary with the aid of microwave energy in a manner to control the working tenperature of the bed (3,4) as a sta in controlling the mold-producing process to a desired mold-produci rate and/or a desired final product.

22. A plant according to Claim 21, ch a r a c t e r i z e d by means for controlling the moisture content of the bed by redistrib water in the bed, evaporating water from the bed or delivering wate to the bed or a combination of these features as a stage in control the mold-producing process to a desired mold-producing and/or a desired final product.

23. A plant according to Claims 21 or 22, ch a r a c t e r i z e by means for controlling the flow of air to the bed as a stage in controlling the mold-producing process to a desired mold-producing rate and/or a final product.

24. Plants according to Claims 21, 22 or 23, ch a r a c t e r¬ i z e d fcy means for measuring the amount of carbon dioxide leavin the bed, wherein the value measured is intended for use as an indic tion of the mold-producing rate and, when applicable, as a basis fo controlling the delivery of air to the bed.

25. A plant according to Claims 21, 22, 23 or 24, charac¬ ter i z ed in that a container (1) for the bed (3, 4) includes casing (13) which is constructed to prevent spreading of microwaves from the interior of the container to the surroundings, for instanc in the form of a metallic casing (13) .

26. A plant according to Claims 21, 22, 23, 24 or 25, c h a r a c t e r i z e d in that a bed container is coated internally with a corrosion resistant coating (14) , for instance a coating comprised plastic, rubber or seme other material having dielectric propertie such as not to be heated, or at least not heated to any significan extent, fcy the microwaves.

27. A plant according to Claims 21, 22, 23, 24, 25 or 26, cha r a ct er i z e d fcy at least one microwave generator (21) whic connected to a bed container (1) directly or throu the intermedi of a waveguide (15, 40) , for instance in the form of a tube (16, 4 of specific dimensions.

28. A plant according to Claims 21, 22, 23, 24, 25, 26 or 27, ch ar a ct er i z ed fcy control means intended for reducing required active time of microwave generators included in the plant, for instance with the aid of a thermostat having a dead zone.

29. A plant according to Claims 21, 22, 23, 24, 25, 26, 27 or 28, cha r a c t e r i z e d fcy means for adapting bed temperature w regard to those microorganisms which provide the best decompositio rate at each stage of the process.

30. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28 or

29, ch a r a ct er i z ed fcy means (17) for adjusting the ave tenperature of the bed in a manner to maintain a predetermined idea temperature, in the case of an aerobic process a tenperature of abo 40°C for instance, and such as to restrict the maximum bed tenperat so as not to exceed a predetermined value, for instance a tenperatu value of about 60°C in the case of an aerobic process.

31. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30, ch ar a ct er i z ed by means for sustaining an anaer process.

32. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29 30 or 31, ch ar a ct er i z ed fcy means (17) for interruptin heating of the bed and, when appropriate, for suppling water to the bed when the bed moisture content falls beneath a predetermined val

33. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29 30, 31 or 32, c h a r a c t e r i z e d fcy means for sealing con¬ tainer openings and, when appropriate, container seams against microwaves, for instance with the aid of a fine-mesh metal net (31) or equivalent means.

34. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29 30, 31, 32 or 33 ch a r a c t e r i z e d by means for interrupt the generation of microwave energy when container closures (32, 45) are opened, for instance to deliver material to the bed.

35. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29 30, 31, 32, 33 or 34, c h a r a c t e r i z e d fcy at least one thermoelement (27) for measuring bed tenperature, and fcy metallic devices intended for screening sensors (28) and lines (29) of the element from microwaves.

36. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29 30, 31, 32, 33, 34 or 35, c h a r a c t e r i z e d fcy means (30) for measuring the moisture content of the bed indirectly, fcy measur the moisture content of the exiting air, said measuring location being placed outside the bed container.

37. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29

30, 31, 32, 33, 34, 35 or 36, ch a r a c t e r i z e d fcy a slop surface (7) which is intended to support the bed and which includes downwardly open grate means (8) through which air is delivered to t bed.

38. A plant according to Claims 21, 22, 23, 24, 25, 26, 27,. 28, 2 30, 31, 32, 33, 34, 35, 36 or 37, ch a r a c t e r i z e d in th composting of the material is intended to be effected batchwise, wherein a rotatable or oscillatable container and/or a rotatable or oscillatable agitator is provided and wherein material is intended be delivered to the bed and removed therefrom batchwise.

39. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29 30, 31, 32, 33, 34, 35, 36 or 37, cha r a c t e r i z e d in t composting is intended to be effected mainly continuously, wherein rotatable or oscillatable container (1) , for instance a generally cylindrical container, to which bed material is delivered to the proximity of one end (34) of the container and removed in the prox of the other end (35) of said container, and wherein the container constructed so that the bed will move towards said other end.

40. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 2 30, 31, 32, 33, 34, 35, 36, 37, 38 or 39, ch a r a ct er i z e by means for removing surplus liquid from the bed, for instance perforations in the container.

41. A plant according to Claims 38, 39 or 40, c h a r a c t e r i e d in that the container is rotatably mounted in an encapsulating casing (41) which is constructed for the delivery and removal of material and for the removal of liquid and vapour.

42. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29 30, 31, 32, 33, 34, 35, 36 or 37, ch ar a ct e r i z e d fcy means for layering the bed at a maximum thickness of up to about 20 mm.

43. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41 or 42, c h a r a c t er i z ed fcy grate means on which the layer or layers of mater is/are disposed and which are intended, at the same time, to form supports for said layer or layers and also to provide means for supplying and distributing microwave energy and, preferably, also a to said layer or layers.

44. A plant according to Claims 42 or 43, ch ar a ct e r i z e by grate means which are intended to form supports for a first laye and to form a microwave applicator for a second, underlaying layer.

45. A plant according to Claims 42, 43 or 44, c h a r a c t e r i e d in that the distances between the material layers in a multi- layer plant is adapted so that microwave energy can be delivered to two sides of the layers.

46. A plant according to Claims 42, 43, 44 or 45 c h a r a c - t e r i z e d by means for delivering microwave energy directly to grate means.

47. A plant according to Claims 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45 or 4 ch a r a ct er i z ed in that it is comprised of a mold-produc toilet intended primarily for night soil and optionally kitchen waste, or is intended as a compost plant for primarily kitchen was and garden waste, primarily for multi-family use, or a compost plan for composting waste material, such as industrial experimental kitc waste and the like, on an industrial scale.

48. A method for delivering microwave energy and preferably also a to layered material, ch a r a ct e r i z e d by delivering micr wave energy and preferably also air to the layered material through the medium of grate means which support the layered material.

49. A method according to Claim 48, ch a r a c t e r i z e d fcy delivering microwave energy and preferably air to the layered mater through the medium of overlying grate means which support a layer o material.

50. A method according to Claims 48 or 49, c h a r a c t e r ¬ i z e d by adapting the spacing between layers in a multi-layer plant so that microwave energy can be delivered to the layers from two sides thereof.

51. A method according to Claims 48, 49 or 50, c h a r a c t e r- i z e d by delivering microwave energy to said grate means directl

52. A method according to Claims 48, 49, 50 or 51, c h a r a c ¬ t er i z ed by delivering microwave energy to said grate means indirectly and herewith form secondary antennas for capturing and emitting microwave energy.

53. An arrangement for delivering microwave energy and preferably air to layered material, c h ar a c t e r i z e d fcy grate mean which support layers of the material to be composted and which fun to deliver microwave energy and preferably also air to said layere material.

54. An arrangement according to Claim 53, c h a r a c t e r i z in that said grate means are intended to deliver microwave energy preferably air to an underlying layer of said material.

55. An arrangement according to Claims 53 or 54, c ha r a c ¬ t e r i z e d in that the distance between the layers of a multi- arrangement is adapted so that microwave energy can be delivered t layers from two sides thereof.

56. An arrangement according to Claims 53, 54 or 55, cha r a c t er i z ed in that said grate means are intended to be supplie with microwave energy and preferably air directly.

57. An arrangement according to Claims 53, 54, 55 or 56, ch a ¬ r a ct er i z ed in that said grate means include elongated mutually adjacent and essentially mutually parallel elements, e.g. tubular elements, which are intended to support a layer of material to be composted and to conduct and emit microwave energy and prefer to conduct and emit air.

58. An arrangement according to Claims 53, 54, 55, 56 or 57, c h r a cter i z ed in that said grate means include elongated, mutually adjacent and essentially mutually parallel elements which are intended to be supplied with microwave energy indirectly and herewith form secondary antennas for capturing and emitting microwa energy.

59. An arrangement according to Claims 53, 54, 55, 56, 57 or 58, character i z ed fcy grate means which are disposed in at least two different levels.