The invention belongs to the sector of mechanical engineering and refers to a method and to a hybrid system for drying organic biodegradable waste aiming to the production of a low granulometry stabilized mass for multiple uses.

The term organic biodegradable waste includes a wide variety of waste from the municipal solid waste such as:

^■ Waste from kitchens, such as vegetable and fruit peels

^■ Waste from gardens, such as grass and twigs due to pruning

^■ Cartons and newspapers (in some cases)

The new European and national institutional framework for the management of solid waste constantly sets stricter specifications, which are expected to demand from the local societies significant -and expensive- changes regarding the way they manage their waste. More specifically, the Ministerial Decision 29407/3508/2002 incorporating into national law the European Directive for landfill (1999/31 EU) sets gradually increasing targets to redirect biodegradable solid waste (BSW) from the territorial disposal, starting as from year 2010.

In order to achieve the redirection of BSW the following can be developed:

(a) minimization programs (mostly composting at home, remains of cut grass on the ground and reduction of paper consumption),

(b) separate sorting and biological treatment (that is, composting or anaerobic digestion) of the net organic fraction,

(c) mechanic-biological treatment (MBT) of the lower purity organic fraction, that is received after the mechanic sorting and

(d) thermal treatment (combustion, gasification, cracking) of mixed waste.

In the E.U. 120-140 million tons of bio-waste are produced every year of which almost 90 million tons is food waste. According to the present institutional framework of the E.U. and of each country-member separately, the best way to process bio-waste, whose creation cannot be prevented, should be chosen considering the special conditions prevailing on each area. Some member states have already reduced significantly and are expected to reduce even more the landfill of bio- waste and to increase their biological treatment. Yet in 2010, of the bio- waste produced in E.U. 40% (on average) is led to landfills whereas this percentage in some countries reaches 100%.

According to the ECN (European Compost Network) data it is estimated that 25% of the produced bio-waste is led to composting and anaerobic digestion units for management, with Germany (800 units) and Austria (461) to possess the largest percentage and Italy (240), Gr. Britain (220) and Netherlands (70) to follow.

The main methods currently used for bio-waste management in household level, is household composting and household anaerobic digestion with household composting being the most widespread technique between the two. However these two techniques present several problems in their implementation, such as: difficulty in correct implementation by residents, production of undesirable odours, appearance of insects and micro organisms dangerous to health etc.

The present invention constitutes a drying method of organic biodegradable waste which combines the synergistic action of the photo degradation and of the mechanical degradation and of the waste.

Through technical methods of ageing of the material to be treated into special hybrid systems, their instant degradation and gradual dehumidification is achieved, resulting to the production of an organic stabilized mass of low granulometry suitable for multiple uses.

The required actions that can be fulfilled for the instant drying and granulation of the material to be treated, are: a) Adiabatic treatment of the material via an appropriate device (special lamp) of photo degradation and drying. This process takes place firstly as a part of the pre-treatment of the entering material so that the inactivation of some micro-organisms is achieved and the required drying time is reduced. In this way, the produced steam under vacuum is removed (no humid residue) and the probability of natural and chemical dangers for the environment is decreased. b) The continuous mechanical degradation of organic waste into low granulometry through continuous vertical rotary agitation so that the final drying and the material's transformation into low granulometry stabilized mass is achieved. This activity occurs simultaneously with the photo degradation process for a rapid and more effective performance of the method.

The invention also refers to a system that applies this method.

Below, there is an omnibus revealing of the method's stages and of the system applying it:

1 ^st step: Input of the organic biodegradable waste into the system- operation planning

2 ^nd step: Photo degradation-exposure to a drying lamp, as a pre- treatment stage

3 ^rd step: Mechanical waste degradation in order to receive particles with a desirable size smaller than 3 cm using for this purpose a continuous horizontal rotary agitation device (7)

4 step: Parallel continuous photo degradation -Final drying

5 ^th step: Parallel under-pressure suction and removal of the produced gases

6 ^th step: Remaining material to be dried and to be removed safely

The current invention refers to a hybrid drying system of organic biodegradable waste and it consists of:

^■ The main drying unit of organic biodegradable waste (1). It constitutes a chamber of metal robust manufacture and it can have various forms (cylindrical or rectangular cross-section etc.).

^■ At least one transparent durable container (2), of a preferably crystal manufacture for the collection of the final stabilized mass, of suitable cross-section that is precisely adjacent to the bottom of the main drying unit (1).

^■ At least one supporting base of the system (3) that is of plastic manufacture.

^■ A mechanically opening input door (4), for the safe and controlled waste input.

^■ At least one removable perforated chamber of metal robust manufacture (5) which can have various forms (cylindrical or rectangular cross-section etc.) which is placed concentrically and coaxially inside the main drying unit (1) of organic biodegradable waste. The dimensions of the removable perforated chamber are such, so that suitable space can be available between its exterior covering and the interior of the main drying unit (1), enabling its easy removal and placement. ^■ At least one photo degradation and drying device (special lamp) (6), which is placed in the internal space of the input door (4).

^■ At least one continuous horizontal rotary agitation device (7), which is placed at a suitable height inside the removable perforated chamber of metal robust manufacture (5).

^■ At least one device for the gas under-pressure suction (8)

^■ Control and handling unit, placed on the upper exterior surface of the main unit (1), which has all the appropriate buttons and activation switches, via which all the required operations are achieved such as: control of operation parameters, planning of operation time etc.

The current invention can be fully understood with the help of the detailed description that follows, in relation to the attached drawings, in which:

Drawing 1 presents a front and a side view of a hybrid drying system of organic biodegradable waste.

Drawing 2 presents a perspective aspect of a hybrid drying system of organic biodegradable waste according to the present invention.

Drawing 3 presents a section of the front and of the side view of a hybrid drying system of organic biodegradable waste according to the current invention.

Below, there is a concise reveal of the method's stages and of the mechanical system applying it:

1 ^st step: Input of the organic biodegradable waste into the system- operation start

As shown in Drawing 1, the mechanically opening input door (4) is placed on the upper external part of the main drying unit (1), for the safe and controlled waste input. When the input door (4) is opened, the inner surface of the removable perforated chamber of metal robust manufacture (5) is visible, where the organic biodegradable waste to be dried is placed.

As soon as the waste input is completed, the user can close the mechanically opening input door (4) so that the operation of the system can start. The input door (4) is firmly closed so that there is no gas leakage to the surrounding space. Via the use of the external control unit, the planning and the continuous operation control is achieved. Additionally, the input door is a safety door that enables the automatic interruption of operation during its opening.

2 ^nd step: Photo degradation-Exposure to a drying lamp, as a pre- treatment stage

Photo degradation is the degradation with the effect of solar light. This degradation constitutes a basic case of 'ageing', since solar light constitutes a basic element of atmospheric conditions. Photo degradation offends the ill places of the material and the offence's extent increases as long as the energy increases, that is to say as long as the wavelength of light is decreased. The light absorption leads to the alteration of the electronic imaging (configuration) and to the transition towards a molecular excited state, in which partial inactivation of the contained micro-organisms occurs with a parallel beginning of the shrinkage (reduction of the special surface of the material and the contained humidity) of the material to be processed. Especially in the case of organic biodegradable waste, with humidity percentage above 70%, the pre-treatment with radiant emittance achieves the reduction of drying time but mainly the avoidance of humid residue production.

The device (special lamp) of photo degradation and drying (6), is placed in the inner space of the input door (4), is covered by a special material for its protection and the power depends on the entering volume and the dimensions of the main unit.

3 ^r step: Mechanical waste degradation achieving particles with a desirable size smaller than 3cm and using for this purpose a continuous horizontal rotary agitation device (7).

Parallel to the photo degradation of the entering material, its continuous agitation is also fulfilled, so as to achieve the final drying and the transformation of the material into a low granulometry stabilized mass.

The continuous horizontal rotary agitation device (7), includes at least one agitation ring of metal manufacture and of horizontal axis, of appropriate cross section, so that during the rotation it will be adjacent to the inner walls and the bottom of the inner removable perforated chamber of metal robust manufacture (5). The planning has been predicted beforehand so that during its rotation it can drift and stir all the entering material as well as that assembling in the inner walls of the internal perforated chamber of metal robust manufacture (5).

It can be of various dimensions depending on the needs and the size of the main drying unit and it can turn itself in high rotational speed and towards both directions.

Movement occurs via a gear motor (9) which has power equal to the system's size and capabilities.

The synergistic process of agitation is essential in the case of organic biodegradable waste due to the particularity of the drying application. More specifically:

Immediately after the initial contact of the material with the light degradation device, the temperature of the solid is altered until it reaches a constant rate. This stage is known as constant-rate drying period.

The previous period ends when the material acquires a transitional, but fixed moisture rate for each material that is called critical moisture content. After this point its surface temperature rises and the drying rate falls quickly. The falling-rate drying period is larger in duration than the constant-rate drying period although moisture dehumidification is comparatively greatly smaller.

In organic biodegradable waste, moisture constitutes an essential part of their structure or is trapped in fibers or pores. Moisture flow is slow and is likely to happen with the diffusion of liquid into the structure of solid. As a result, the drying curves of these materials show very small constant-rate periods that end up in high rates of critical moisture content. Moisture balance is generally high, suggesting that a significant amount of water is withheld so steadily by the structure of the solid or into its tiny pores, so that its vapor pressure is significantly reduced. The outer layers tend to dry earlier than the inner ones.

Via continuous agitation, the process of the desirable drying is accelerated, since due to the rotary speed, the moisture reduction rate increases and the mechanic degradation is achieved.

4 ^th step: parallel continuous photo degradation -final drying

As it has already been mentioned, parallel to the mechanic degradation via the device of continuous horizontal rotary agitation, exposure to a special lamp of light degradation and drying is fulfilled for the effective and rapid drying of the material. During the operation, the continuous separation of the dried-stabilized mass from the removable perforated chamber of metal robust manufacture is realized, based on granulometry, towards the transparent durable container, preferably of plastic manufacture, for the collection of the final stabilized product.

5 ^th step: Parallel under-pressure suction of the produced gases and their removal

Via an appropriate suction pump (9), connected to the inner surface of the removable perforated chamber of metal robust structure (5), the safe and parallel under pressure suction of the produced gases-steam is realized, as well as their condensation and their safe transport to every sink's siphon.

The motor is outside the gas flow and has a high suction capacity. The absorption occurs in the inner space of the removable perforated chamber of metal robust manufacture (5) and then the safe transport and release to each sink's siphon occurs.

6 ^th step: Remaining of the material to be dried and its safe removal

As mentioned in step 1 , through the use of the external control unit the planning and the continuous control of operation is achieved. Also the duration of the staying of the material to be dried is precisely determined so that it can turn into low granulometry stabilized mass. The required time fluctuates according to the system's size- and the required capacity.

After this procedure, the mechanically opening input door (4) is unsealed, and via handles (10), the main drying unit (1) is removed, the transparent durable container (2) is removed, is evacuated, it is placed again to the supporting base of the system (3) and then the main drying unit is absolutely adjacent and fixed (1) precisely above the transparent durable container (2) and the system is ready for a new use.

The first important advantage presented by this method is that it is an absolutely ecological treatment method of organic biodegradable waste, since no gaseous pollutants are emitted into the atmosphere nor liquid hazardous waste, which would require proper disposal, is created. The current method contributes to the reuse and utilization of waste, it contributes to energy recovery and therefore it does not present all the dangers that the current waste management practices involve for the environment and humans.

Another advantage of the current method is that it converts the organic waste streams into low granulometry stabilized mass which can have multiple uses such as fuel without pre-treatment, bio-ethanol production after management, as compost or raw material for compost etc.

Furthermore, through this method there is a significant reduction in waste volume, since organic biodegradable waste consists of at least 70 % humidity. Through the synergistic effect of mechanical degradation and photo degradation, the reduction of original volume is realized up to 90% while reducing the microbial load.

A subsequent advantage of this is that the implementation of the current method does not further burden the environment, since it is a method of waste management extremely safe for the environment. This results in high benefit for the environment and economic profit for the system holders since they can sell the final product (stabilized mass of low granulometry) to any recipient for any possible exploitation.

Finally, an important technological advantage of this method in relation to other drying systems is its effective and rapid implementation, taking advantage of both actions of degradation (mechanic and photo).

In most drying methods, hot air is used to alter the surface of the material per weight unit and it contributes to the development of a hard layer, impenetrable to moisture flow. This means that moisture cannot be easily extracted from the interior at the solid surface or at the boundary where drying takes place. This decreases drying significantly both quantitatively and qualitatively.

In the current method, besides the rapid shrinkage by the action of photo degradation, the simultaneous action of continuous agitation (mechanic degradation) occurs and contributes to the continuous movement of moisture and therefore to the faster and more efficient drying of the material.