WO2012019977A1 - Apparatus for processing organic waste - Google Patents

Abstract

An apparatus for the processing of wet organic waste is disclosed. It comprises a heated treatment chamber (4) wherein a stirrer and an outflow circuit of vapor-rich air are housed, intended to carry on a drying treatment on said waste, said treatment chamber consisting of a heated, basket-shaped body (40) with an upper mouth (41, 10) sealed in an airtight manner by a relative lid (11), said outflow circuit is also arranged in an airtight manner and puts in communication said heated basket (4) with a condensation unit (5) in turn in airtight communication with a removable drawer (6b) for condensate collection, wherein the apparatus further houses a double mixing system comprising a mixing arm (42), rotatably mounted on a main rotation axis within said heated basket-shaped body (4), and a helical screw (44) housed in an auxiliary chamber (40a) in communication with and arranged on the side of said basket-shaped body (40), said helical screw (44) having a second rotating axis not parallel to said main axis and said helical screw (44) being apt to sweep at least an area adjacent to said arm (42) and wherein at least said helical screw (44) is able to be rotated clockwise and counter clockwise, in one of the two directions the screw (44) within the auxiliary chamber operating as a rising hopper.

Description

APPARATUS FOR PROCESSING ORGANIC WASTE

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Field of the Invention

The present invention refers to a processing apparatus for the disposal of organic waste, in particular for domestic use .

Background Art

As known, the processing of domestic waste is increasingly becoming of critical importance for city administrations . The increasingly smaller spaces for landfill sites and strict disposal laws, together with ecology and environmental conservation issues, impose city administrations to optimize the entire chain of waste collection, differentiation and disposal.

A significant proportion of domestic urban waste consists of so-called "wet" waste, i.e. non-dry organic matter. Typically this waste is separated at user level, in containers or biodegradable bags, and then collected and disposed of by the municipal street cleaning and refuse disposal services in suitable conversion areas, where the waste decomposes into compost or other recyclable organic material.

Of course, this requires to organize a specific collection service, often carried out "door-to-door" to avoid the accumulation of large amounts of perishable organic material, which would be detrimental from a hygienic point of view. As known, users are not keen on having to manage wet waste collection, as it is biologically active material rich in water which hence tends to perish, giving off odor and releasing sewage. Especially in a flat, wet waste collection implies a series of drawbacks connected with odor, space occupation and the centra- lized management of waste waiting for the collection by the municipal street cleaning and refuse disposal services (collection bags are subject to attacks by stray animals) . Those who have an outdoor space often resort to composters for the disposal of organic waste; but also composters are not devoid of problems, as they are a receptacle for insects and wild animals and a source of odors, especially with high outdoor temperatures .

In order to solve these problems, devices for the processing of organic waste have been proposed for installation within individual households . These apparatuses typically have the purpose of drying the organic material as much as possible, so as to reduce its volume and remove the bacterial flora which is the source of odors. They comprise a loading compartment, where the organic material is poured, provided with mixing means, for example in the shape of a rotating arm. The compartment is heated in order to cause the drying of the organic material. The heated air, rich in humidity, is caused to condense so as to extract and then dispose of the liquid component. Ideally these apparatuses should solve the problem of wet waste collection, since they greatly reduce the volume of waste, producing as a result a relatively small amount of compost, which can be used again for the growing of plants, or to be disposed of with dry waste.

Typical examples of such apparatuses are described in US5925321A, US2003036190A, WO08150059A, US5534042A.

Prior-art apparatuses, however, are subject to some drawbacks. Firstly, they are conceived with a complex and bulky construction, especially in a vertical direction; as a matter of fact, they normally provide a waste collection compartment, below which a series of parts for controlling, channelling and unloading waste are arranged, which remarkably increase the vertical bulk thereof.

Moreover, they provide a discharge of the condensation water extracted from the organic material, which discharge must be connected to a sewage drain, typically in correspondence of a sink drain: this implies a specific installation which is often not within the reach of the common user. Finally, they are often a source of odors, due to aerobic bacterial digestion, which escape out from the loading compartment and/or condensation drain. Normally these drawbacks do not represent a source of worry for manufacturers, because it is commonly believed that such apparatuses are meant for installation in an isolated area underneath a sink, in the suitable compartment normally provided for waste collection. In actual fact the Applicant has detected that users do not appreciate such traditional approach. As a matter of fact, the compartment below a sink is not easily accessible, especially if electric switches must be activated; moreover, localized heating, within a compartment which normally provides no ventilation, is a source of worry; again, the need to call a plumber or other expert for the cor- rect connection of the apparatus to the sewage drain discourages from installing the apparatus; finally, the exhalation of odors from the condensation drain or from the loading door leads to quickly abandoning this disposal practice.

Further disadvantages deriving from the known designs of this type of equipment are the jamming of the stirring mechanism , due to the presence of harder organic residues (such as bones, seafood shells, and so on), as well as the complexity and the cost of the temperature adjustment system.

Other prior-art machines are disclosed in WO2007/029954 and WO2008/150059. These apparatuses too are not fully satisfactory with respect to the technical problems indicated above. Summary of the Invention

The object of the present invention is hence to provide an apparatus for the treatment of organic waste which overcomes the drawbacks just cited. In particular, it is meant to provide a sufficiently economical and compact apparatus, suitable for processing effectively at least 2-3 Kg of organic waste without producing any odor and ready to use, i.e. which requires no specific connection or installation. Moreover, it is wished to provide such an apparatus which is sturdy and durable, also in consideration of possible tenacious organic waste , and which achieves a perfect dehydration without having to use complex control and adjustment systems.

Such objects are achieved through an apparatus as de- scribed in its essential features in the attached main claim.

Other inventive aspects of the apparatus are described in the dependent claims .

In particular, according to a first aspect of the invention, it is provided an apparatus for the treatment of wet or- ganic waste, comprising a heated treatment chamber wherein a stirrer and an outflow circuit of vapor-rich air are housed, intended to carry on a drying treatment on said waste, said treatment chamber consisting of a heated, basket-shaped body with an upper mouth sealed in an airtight manner by a relative lid, and said outflow circuit is also arranged in an airtight manner and puts in communication said heated basket (4) with a condensation unit (5) in turn in airtight communication with a removable drawer (6b) for condensate collection, wherein the apparatus

houses a double mixing system comprising a mixing arm, rotata- bly mounted on a main rotation axis within said heated basket- shaped body, and a helical screw housed in an auxiliary chamber in communication with and arranged on the side of said basket- shaped body, said helical screw having a second rotating axis not parallel to said main axis and said helical screw being apt to sweep at least an area adjacent to said arm and wherein at least said helical screw is able to be rotated clockwise and counterclockwise, in one of the two directions the screw within the auxiliary chamber operating as a rising hopper.

According to another aspect, below said basket-shaped body a gearmotor assembly) is arranged, apt to drive into rotation at least one first shaft of said mixing arm.

The auxiliary chamber ends above with an ejection opening communicating with a flanged mouth facing downwards and communicating in an airtight manner with a removable drawer for the collection of dry residues.

According to a further aspect, the helical screw is integral in rotation with a displacement tooth arranged in the proximity and downstream of said ejection opening to push dry residues towards said flanged mouth.

The auxiliary chamber communicates with the inside of said basket-shaped body through an opening flush with the bot- torn surface of said basket-shaped body.

Preferably, the gearmotor assembly drives into rotation also a second shaft integral in rotation with a drive shaft of said helical screw.

The helical screw has a longitudinal rotation axis pre- ferably inclined with respect to said main rotation axis of an angle ranging between 15° and 80° °, preferably lesser than 30°.

According to a further aspect, the condensation unit is arranged on a rear side of said basket-shaped body, opposite to said auxiliary chamber, and is connected through an inlet hose to the inner compartment of said basket-shaped body.

Preferably, the condensation unit is connected to the inner compartment of said basket-shaped body also through a vent hose which diverges towards a condensation chamber of said unit .

The condensation unit comprises a condensation chamber provided with a cold wall in contact with a flap dissipator (55) and Peltier cells (57) are installed on said cold wall.

According to a preferred aspect, the heated, basket- shaped body consists of a lower, vase-shaped portion and of an upper lid-shaped portion, mutually joined in an airtight manner, the upper lid portion comprising a loading opening consisting of a relief ribbing ending with a perimeter gasket.

Preferably, the lower vase-shaped portion is made of metal material and said upper lid portion is made of a plastic material .

According to a different aspect of the invention, it is provided a method of drying waste material in an apparatus as claimed in any one of the previous claims, wherein

the current temperature within said processing chamber is detected and compared against an upper threshold temperature just above 100°C,

upon the current temperature rising over said upper thre- shold temperature, a heating device of the apparatus is turned off,

the time delay (duty cycle) for the system to naturally drop from the upper threshold to a predetermined lower threshold is counted,

upon the current temperature reaching the lower threshold the heating device is turned on again,

the above cycle being continued until said time delay (duty cycle) has a duration longer than a predetermined time threshold (Emax) .

Brief Description of the Drawings

Further features and advantages of the apparatus according to the invention will in any case be more evident from the following detailed description of a preferred embodiment of the same, given by way of example and illustrated in the attached drawings, wherein:

fig. 1 is an exploded view of the apparatus according to the invention;

fig. 2 is a front perspective view of the processing chamber of fig. 1;

fig. 3 is a perspective view from the rear side of the chamber of fig. 2;

fig. 4 is a rear perspective view of the processing cham- ber with the lid portion removed;

fig. 5 is a cross-section view of the chamber of fig. 2 taken from below;

fig. 6 is a longitudinal-section view, passing through the centre of rotation of the mixing arm, of the chamber of fig. 2;

fig. 7 is a block diagram of the operation of the condensation unit; and.

figs. 8A, 8B and 9 are section views and top plane view, respectively, of a further embodiment of the invention.

Fig. 1 shows an overall view of the fundamental components assembled in the apparatus according to the invention.

An outer bodywork casing consists of two parts, a lower one la and an upper one lb which hold within the operative components of the apparatus . Lower bodywork component la acts as basement of the apparatus and has, for such purpose, a plurality of resting feet la'.

Within the bodywork casing, above basement la, there are arranged a box 2 housing electronic circuit boards, a gearmotor assembly 3, a treatment chamber (mixing and toasting) 4 and a condensation unit 5. A plurality of electric connections (not shown) apt to mutually connect the various components is further provided, with also a small base 2a for taking and distributing the electric supply from a network cable.

In the base portion la of the bodywork, on the front, there are furthermore provided two openings for the introduction of removable drawers 6a and 6b, for dry waste and for the collection of condensate, respectively. The two drawers can slide horizontally (with respect to the attitude of the appara- tus during use) and can hence be introduced into basement la and be fully extracted. The drawer for the collection of condensate 6b is put in airtight communication, for example through a pipe (not shown), with condensation unit 5. As better described further on, the dry waste drawer 6a has an upward- facing inlet, meant to abut in an airtight manner with a lower outlet of the hopper system of chamber 4.

Due to the different nature of the material which they are meant to receive, the two drawers are not required to have the same size. Typically, the drawer 6b for the water-based condensate has a greater volume than the dry matter drawer 6a.

According to a preferred embodiment, condensate drawer 6b houses inside a float system, suited to provide an overflow signal to the apparatus control system. When the preset maximum level is reached, the signal generated by the rise of the float prevents the execution of a new operation cycle of the apparatus, until the drawer is emptied. Advantageously, with the view of avoiding any complication and source of sealing disruption , the float is of a type equipped with a proximity switch: for example it is equipped with a magnet which determines the generation of an overflow signal when it is moved closer to a sensor arranged outside above the drawer. In this case it is not necessary to provide any electric contact entering the condensate drawer, because the effect of the magnetic field propa- gates also through the wall thickness.

Bodywork upper portion lb has a loading opening 10 which is closed by a door 11. According to the invention, opening 10 has a seal or perimeter lip suited to seal against the lower surface of door 11. Similarly, in the inner part of opening 10 a second seal or sealing lip is provided, suited to rest in an airtight manner against a perimeter edge of a corresponding loading opening 41 provided in the upper part of chamber 4.

Fig. 2 shows in greater detail the assembly of chamber 4 for the treatment and toasting of organic waste, as well as ad- jacent condensation unit 5.

A main body 40 of the toasting chamber has a generic basket shape, open above through a loading mouth 41.

From a construction point of view, it is preferable for basket-shaped body 40 to be obtained in two pieces, mutually joined in an airtight manner: a lower, vase-shaped portion and an upper, lid-shaped portion. The lower portion of basket 40 (fig. 4) is advantageously made of metal material, for example of cast or pressure-injected aluminum alloy, so as to facilitate the conduction of heat from the heating system which may be located underneath; the upper lid portion can instead be advantageously made of plastic material and be mounted in an airtight manner, for example arranging it in between a gasket, on the underlying metal vase by means of bolts or similar fasteners .

Loading mouth 41 is obtained through a projecting ribbing in the lid portion. As already mentioned, loading mouth 41 is provided, along the perimeter edge, with a sealing gasket 41a, suited to define a seal with the above-lying opening of bodywork upper portion lb.

In the walls of basket 40, in particular of the lower metal portion thereof, there are provided electric resistances suited to internally heat the compartment of chamber 4 as high as a toasting temperature of about 105-130°C. Alternatively, should the machine be sufficiently large, a hollow space is provided in the walls of basket 40, wherein oil is apt to circulate, heated in turn by a separately arranged heater.

For the heating of chamber 4 alternative means can also be used, such as electromagnetic induction, infrared microwaves, , and so on.

In the front part of basket 40, preferably offset by about 20° to the left, an auxiliary chamber 40a is provided, housing an auxiliary mixer; this chamber acts as discharge hop- per and has a cylindrical shape having a perimeter intersecting/touching the internal boundary perimeter of basket 40, as will be detailed further on.

Inside the main compartment of basket-shaped body 40 a mixing arm 42 (clearly shown in fig. 6) is rotatably mounted. Arm 42 is generically U-shaped, with the two U legs 42a and 42b brushing the bottom surface of basket 40 and rising back up to different lengths along the internal lateral surfaces of the basket. A first leg 42a of a longer arm 42 rises back up to a radial distance from the centre of rotation substantially equivalent to that of the inner surface of basket 40. The opposite leg 42b of a shorter arm 42 rises back up at a smaller radial distance (about half of the radial distance of the long- er arm), as clearly visible in fig. 6, thus making the stirring action more effective.

Arm 42 is preferably made of a hard metal material, profiled so as to mix - but also to grind and crumble - the material to be processed. This allows to widen the range of or- ganic wastes which can be processed by the apparatus, for example - in addition to pulpous and soft material - also nuts, shellfish shells, and fish bones, which are typically hard materials .

Arm 42 is rotatably mounted on a shaft axis 43, standing substantially vertically and coming from below-lying gearmotor assembly 3, which will be illustrated in greater detail further on. Arm 42 is intended to rotate on shaft axis 43 at modest speed, in the order of 12-15 rpm.

In the rear part of basket 40, condensation unit 5 is housed, which is contained in a bulk not taller than that of basket 40. Condensation unit 5 communicates with the inside of basket-shaped body 40 through two ports, a vent 44a and an inlet 44b. The two ports 44a and 44b are obtained in the upper part of basket-shaped body 40 (see figs. 2 and 3) and communi- cate with two respective elbow hoses 45a and 45b, preferably obtained integrally with the lid portion of basket 40.

At the exit of elbow hoses 45a and 45b there is engaged, in an airtight manner, the mouth of the respective vent and inlet pipes of condensation unit 5. In particular, a vent pipe 51 opens funnel-like (square section, as can be seen in fig. 2 and in the section of fig. 5) starting from hose 45a, so as to facilitate a first cooling due to the expansion of the air extracted from chamber 40. In the lower terminal part of vent pipe 51 a fan or pump 51a is installed, suited to extract humid air from the chamber inside basket 40 and to push it towards an actual condensation chamber 52. Said condensation chamber, of a flat shape, is in communication also with inlet hose 45b, arranged on the opposite side with respect of pipe 51, through an inlet pipe, also engaged in an airtight manner. The rear side of condensation chamber 52 is sealed by a cold condensation plate 53, typically consisting of an aluminum plate. In the lower part of condensation chamber 52, preferably on the side corresponding to inlet port 45b for reintroduction, a short discharge tube 54 is provided, wherefrom condensed water flows out. Discharge tube 54 is put in airtight communication with the drawer of condensate 6b, as previously mentioned, for example by means of a small pipe of plastic material.

On the rear side of cold plate 53 a flap dissipator 55 is arranged, of a type known per se, preferably forcedly cooled by a pair of small fans 56.

According to a preferred embodiment, between cold plate 53 and dissipator 55 a pair of Peltier cells 57 is also ar- ranged, suitably energized by corresponding electric connectors (not shown) .

With reference to fig. 6, the gearmotor assembly below basket-shaped body 40 can be appreciated. In the gearmotor assembly an electric motor M is integrated, which drives into ro- tation a series of transmission gears which, in turn, drive two drive shafts. On one side, transmission drives shaft 43 for the rotation of mixing arm 42. On the other side, the transmission drives an auxiliary shaft 31 of an auger or helical screw 44 rotatably mounted within cylindrical auxiliary chamber 40a.

According to an embodiment, in order to reduce bulk and achieve a better performing transmission, auxiliary shaft 31 consists of two parts, a first part 31a mounted on bearings according to an axis parallel to main shaft 43, a second part 31b, inclined according to the longitudinal axis of auxiliary chamber 40a and connected to the first part 31a through a cardan joint or other bevel gear. The first part 31a and the main shaft 43 of mixing arm 42 are mutually connected in rotation, for example through a transmission belt 32 acting on two transmission wheels 33 and 34.

Preferably, both shafts 31 and 43 are provided with a gasket at the intersection with the bottom of auxiliary chamber 40a and of basket 40, respectively. This ensures a perfect, airtight seal also in the lower part of toasting chamber 4. A similar configuration is shown in figg.8A, 8B and 9 representing a further embodiment.

Auxiliary chamber 40a projects along the inclined wall of basket-shaped body 40, forming a hopper-like channel wherein helical screw 44 is rotatably mounted. For bulk optimization and an efficient operation of the rising hopper, helical screw 44 has a rotation axis inclined with respect to the main rotation axis of the arm 42 by an angle ranging between 15° and 80°, preferably in the order of 20-30°.

As clearly visible in figg. 6 and 8A, according to the invention the auxiliary chamber 40a partly intersects the inner volume of basket 40, which leads the coils of helical screw 44 to sweep an area, at the bottom of the basket 40, very close (adjacent) to the area swept by arm 42. The two mixing devices (arm 42 and helical screw 44) hence operate on two converging rotation axes and have mixing members (the legs and the auger) intended to cooperate closely with one another (they operate at a distance no greater than 1-2 cm, preferably up to a maximum of a few millimeters) .

For this purpose, auxiliary chamber 40a is open on one side towards the inner compartment of basket 40: in particular, it has an inlet port 45 which communicates with the inner chamber of basket 40 flush with the lower area, i.e. it connects with the bottom surface of basket 40.

This configuration causes an excellent mixing of the product to be dried: as a matter of fact, the waste is pushed to the periphery by arm 42, i.e. towards auxiliary chamber 40a, wherefrom it is collected by the auger and pushed again backwards. As a matter of fact, during the mixing step, the auger is put in rotation so as to create a downward movement, or a movement towards the bottom of auxiliary chamber 40a, which causes a sort of squeezing of the waste material between the auger and the rotating arm. This action is highly effective also for crushing hard materials, such as bones and shells of seafood, without transversal stresses to the rotation axes of arm 42 and of helical screw 44 being produced

As visible in figs. 4 and 6, auxiliary chamber 40a is closed below and above. At the top a partition 44a defining a partial ejection opening 44b is provided. Shaft 31b of helical screw 44 projects slightly above partition 44a: on the projecting end a pushing tooth 44c is keyed on, integral in rotation with shaft 31b, the usefulness of which will be illustrated in the following.

Partition 44a is arranged perpendicularly to the rotation axis of helical screw 44 and hence inclined with respect to the horizontal: it hence determines an inclined sliding surface, the usefulness of which will be understood in the following of the description.

In the top part, auxiliary chamber 40a, which ends slightly below the top of basket 40, is further sealed in an airtight manner by a cap 46. Said cap encloses the top area, where pushing tooth 44c is housed, as well as a side portion of flanged mouth 47, projecting frontally from auxiliary chamber. The cap is preferably integral with the lid portion of basket 40 and is fastened to auxiliary chamber 40a by removable fastening means, such as Allen screws 46a, so as to be able to be disassembled and allow access to the below-lying auxiliary chamber. Also in this area a seal below cap 47 is suitably provided so as to guarantee an airtight seal.

Similarly, also partitioning 44a is removably fastened, so that it may be disassembled to remove helical screw 44 and facilitate any maintenance work.

Flanged mouth 47 opens downwards (throughout the present application, the terms "down" and "up" refer to the attitude of the apparatus in its normal operation condition) and is coupled with a further collector 48 which puts in communication - always in an airtight manner - auxiliary chamber 40a with the be- low-lying drawer of dry residues 6a.

Since collector 48 is arranged substantially vertically above drawer 6a, the pouring off of material from the top of the auxiliary chamber to the drawer occurs by simple fall. It can be appreciated (fig. 6) that the drawer of dry residue 6a is housed in the space below auxiliary chamber 40a which is inclined vertically, thus obtaining an advantageous compacting of bulks .

During its standard operation, helical screw 44 is caused to rotate so as to push downwards any material it may catch as explained above: thereby a sort of recirculation of the material is obtained, which material is pushed into the auxiliary chamber by rotating arm 42 upon its passing in front of side opening 45.

When the operation cycle is completed, it is provided to invert the direction of rotation of the motor and hence of screw 44 and of arm 42. With such rotation, screw 44 tends to lift the material upwards, which material is pushed into the auxiliary chamber 40a by arm 42. At the end of the cycle, hence, the dry and crumbled material is lifted by helical screw 44 until it comes out of the opening 44b of partition 44a. In this position, rotating tooth 44c provides to push the dry material towards flanged mouth 47, along the inclined plane of partition 44a, so as to cause it to fall into drawer 6a.

The operation cycle of the apparatus is controlled so as to dry the waste material, removing water-based liquid towards drawer 6b, and then expelling it towards drawer 6a. For performing such work cycle it is sufficient to determine when the waste material has reached a negligible degree of humidity: according to the invention this is established by verifying a duty cycle of the basket cooling , through a single temperature probe .

In particular, one begins from the consideration that the heating of the wet waste results in the generation of vapor due to the aqueous component of all organic materials . The change of state of water (evaporation) contained in the material to be processed causes the temperature of the main basket to remain substantially constant around 100°C during this change. The va- por is continuously and progressively taken from the basket and caused to condense, obtaining water in its liquid state which is channelled into the suitable watertight container. The continuous condensing progressively reduces the water content in the system and prevents the basket pressure from exceeding ac- ceptable values. As a safety measure, however, a bleed valve can be provided, which may be automatically actuated upon the exceeding of a preset pressure value , also equipped with anti- odor filter. Continuing in the dehydration cycle, the amount of water contained in the waste drops and with it also the energy required for the evaporation of the same. The system hence receives a surplus of thermal energy - which is delivered based on a preset nominal value - which hence translates into a progressive increase of the temperature of the basket and of the product therein contained, even beyond 100°C, up until reaching a set higher threshold temperature Tl (for example 105°C) . Upon reaching such threshold temperature, the control system of the apparatus cuts off the supply to the heating element. At this point it is measured for how long the heating element remains turned off, until a lower threshold temperature is reached T2 (for example 95°C) . This natural cooling time from Tl to T2 is called duty cycle. When the system temperature drops below T2, the heating device is activated again and the maximum duration and the measure of the duty cycle is memorized. In the subsequent repetitions of the event the duty cycle time is compared with the previous stored one and the longer one is stored. Continuing in the dehydration cycle, the Duty Cycle increases (the amount of water to be evaporated dropping) up until it reaches a preset Emax time, determining the end of the cycle.

This simple check on the duty cycle times makes the control system very simple , reliable and economic, since one can resort to simply a temperature probe and to a time counter.

Based on the detailed description reported above, it is now possible to understand the operation of the apparatus.

The user opens airtight door 11 and easily introduces from above the organic waste into basket 40. Due to its specific construction, the machine is capable of accepting a wide va- riety of different waste, except very hard and bulky ones (for example large cattle bones) . In the household version, the apparatus has a basket capable of receiving about 2-2.5 Kg of residue .

Upon starting, a management programme starts the heating of basket 40, as high as 105-110°C, controlling the temperature thereof through a thermocouple. At the same time gearmotor 3 is put into motion, so that arm 42 and screw 44 are driven into rotation at the desired speed. The waste material is thus mixed and crushed , also due to the cooperation between arm 42 and screw 44 simultaneously operating (said screw rotating so as to push the material downwards) . At the same time the wet waste is heated and begins to evaporate. The vapor is continuously removed from the main chamber and caused to condense in the condensing unit.

Fig. 7 shows a block diagram of the operation of the condensation cycle obtained with condensation unit 5. Hot air, rich in vapor extracted from the organic waste in chamber 40, is extracted by pump 51a through vent port 44a and caused to pass into unit 5. The hot air undergoes a first cooling by expansion in pipe 51 and a second cooling upon contact with cold plate 53 in condensation chamber 52. The cooling causes water condensation (more or less rich in organic molecules, such as proteins, but free from bacteria - killed by the previous thermal cycle in chamber 40), which is then drained and channelled - through tube 54 - to the drawer of condensate 6b. The dehumidified air is reintroduced into chamber 40 through inlet port 44b and hose 45b.

The mixing and toasting cycle of the organic waste can last on average 2.5-3 hours for a load in the order of 2-2.5 Kg. According to a preferred embodiment, the controller of the apparatus relies on the temperature probe and on the calculation of the duty cycle for determining when the waste material is fully dried: when an acceptable, preset threshold duty cycle value is reached, the toasting cycle is ended. Typically, at the end of the cycle the organic waste has dropped in weight by 75-80%, which has been collected as condensed water in the suitable drawer.

At the end of the toasting cycle, the rotation of the motor is inverted, so as to reverse rotation of screw 44 and to evacuate the basket chamber and pour the dry waste into the suitable drawer. At this point the machine can be stopped and is prepared for the execution of a new cycle.

Depending on the user' s preferences and on the amount/nature of the organic waste treated, the drawers for the collection of the condensate and of the dry matter may be emptied upon each operation cycle or more occasionally, provided the fact that the safeguard represented by the overflow system in the condensate drawer exists .

As can be guessed, the apparatus according to the invention is very effective and convenient, allowing to fully achieve the objects set forth in the premises.

The apparatus is compact and free-standing; it requires no connection to the sewage system and is hence immediately operative and requires no particular installation devices . The gearmotor arrangement which simultaneously controls the main stirrer and the lifter/pusher screw arranged adjacent to the basket, on the front, is particularly compact and effective for mixing the organic waste and for ejecting the dry matter.

The function of the double mixer according to the invention is multiple:

1. It grinds and mixes the contents of the basket

2. By mixing, it allows the even heating of the basket contents and allows the vapor to exit from the wet mass, displacing it

3. It conveys the mass to be treated towards the auxiliary chamber and then towards the drawer in the final expulsion step , allowing to keep the system fully sealed in each operating steps .

In a short time the apparatus is capable of treating the entire volume of organic waste produced by a family in the course of a day, providing as by-product condensation water, which can be disposed of or used for watering plants, as well as a very low volume of solid material, which may be used as compost or disposed of in the dry waste. Neither one of the two by-products gives off odors, nor does it contain bacteria, be- cause it has undergone a sterilizing thermal treatment. Since the entire mixing and toasting chamber and the various pipes are assembled in an airtight manner and form a closed circuit, also during treatment no odor is released.

However, it is understood that the invention is not li- mited to the particular configuration illustrated above, which represents only a non-limiting example of the scope of the invention, but that a number of variants are possible, all within the reach of a person skilled in the field, without departing from the scope of the invention.

For example, it is not ruled out that, instead of a condensation unit with Peltier cells, a condensation unit employing a classic frigorific cycle may be similarly used.

Moreover, although in the description reference has always been made to a finished bodywork casing, it is not ruled out that the operating components of the apparatus may be assembled in a raw frame to be fitted into a piece of furniture; for example, the reduced vertical bulk of the invention would advantageously allow the introduction into a drawer of a piece of kitchen furniture.

Claims

1. Apparatus for the processing wet organic waste, comprising a heated treatment chamber (4) wherein a stirrer and an outflow circuit of vapor-rich air are housed, intended to carry on a drying treatment on said waste, said treatment chamber consisting of a heated, basket-shaped body (40) with an upper mouth (41, 10) sealed in an airtight manner by a relative lid (11), and in that said outflow circuit is also arranged in an airtight manner and puts in communication said heated basket (4) with a condensation unit (5) in turn in airtight communication with a removable drawer (6b) for condensate collection, characterized in that it houses a double mixing system comprising said stirrer in the shape of a mixing arm (42), rotatably mounted on a main rotation axis within said heated basket-shaped body (4), and a helical screw (44) housed in an auxiliary chamber (40a) in communication with and arranged on the side of said basket-shaped body (40), said helical screw (44) having a second rotating axis not parallel to said main axis and said helical screw (44) being apt to sweep at least an area adjacent to said arm (42) and wherein at least said helical screw (44) is able to be rotated clockwise and counter clockwise, in one of the two directions the screw (44) within the auxiliary chamber operating as a rising hopper.

2. Apparatus as in claim 2, wherein below said basket- shaped body (40) a gearmotor assembly (3) is arranged, apt to drive into rotation at least one first shaft (43) of said mixing arm (42) .

3. Apparatus as claimed in claim 1 or 2, wherein said auxiliary chamber (40a) ends above with an ejection opening (44b) communicating with a flanged mouth (47) facing downwards and communicating in an airtight manner with a removable drawer (6a) for the collection of dry residues.

4. Apparatus as claimed in claim 3, wherein said helical screw is integral in rotation with a displacement tooth (44c) arranged in the proximity and downstream of said ejection opening (44b) to push dry residues towards said flanged mouth (47) .

5. Apparatus as claimed in any one of the previous claims, wherein said auxiliary chamber (40a) communicates with the inside of said basket-shaped body (40) through an opening (45) flush with the bottom surface of said basket-shaped body (40) .

6. Apparatus as claimed in any one of claims 2 to 5, wherein said gearmotor assembly (3) drives into rotation also a second shaft (33) integral in rotation with a drive shaft (31b) of said helical screw (44) .

7. Apparatus as claimed in any one of the previous claims, wherein said helical screw (44) has a longitudinal rotation axis inclined with respect to said main rotation axis of an angle ranging between 15° and 80°, preferably lesser than 30°.

8. Apparatus as claimed in any one of the previous claims, wherein said condensation unit (5) is arranged on a rear side of said basket-shaped body (40), opposite to said auxiliary chamber (40a), and is connected through an inlet hose (45b) to the inner compartment of said basket-shaped body (40) .

9. Apparatus as claimed in claim 8, wherein said condensation unit (5) is connected to the inner compartment of said basket-shaped body (40) also through a vent hose (45a) which diverges towards a condensation chamber (52) of said unit (5) .

10. Apparatus as claimed in any one of the previous claims wherein said condensation unit (5) comprises a condensation chamber (52) provided with a cold wall (53) in contact with a flap dissipator (55) and Peltier cells (57) are installed on said cold wall (53) .

11. Apparatus as claimed in any one of the previous claims, wherein said heated, basket-shaped body (40) consists of a lower, vase-shaped portion and of an upper lid-shaped portion, mutually joined in an airtight manner, the upper lid portion comprising a loading opening (41) consisting of a relief ribbing ending with a perimeter gasket (41a) .

12. Apparatus as claimed in any one of the previous claims, wherein said lower vase shaped portion is made of metal material and said upper lid portion is made of a plastic material.

13. Method of drying waste material in an apparatus as claimed in any one of the previous claims, wherein

the current temperature within said processing chamber is detected and compared against an upper threshold temperature (Tl) just above 100°C,

upon the current temperature rising over said upper threshold temperature, a heating device of the apparatus is turned off,

the time delay (duty cycle) for the system to naturally drop from the upper threshold (Tl) to a predetermined lower threshold (T2) is counted,

upon the current temperature reaching the lower threshold (T2) the heating device is turned on again,

the above cycle being continued until said time delay (duty cycle) has a duration longer than a predetermined time threshold (Emax) .