WO2017046822A1

WO2017046822A1 - Multi-year cyclic biodigester

Info

Publication number: WO2017046822A1
Application number: PCT/IT2015/000225
Authority: WO
Inventors: Antonio Bertolotto
Original assignee: Marcopolo Engineering S.P.A. - Sistemi Ecologici
Priority date: 2015-09-16
Filing date: 2015-09-16
Publication date: 2017-03-23
Also published as: WO2017046822A8

Abstract

The present invention relates to a digester for the control of the anaerobic digestion of biomass.

Description

DESCRIPTION

"MUL I -YEAR CYCLIC BIODIGESTER"

Prior art

Among the increasingly recurrent problems in the environmental and energy field certainly are those concerning the methods for converting municipal solid waste, which is often transported long distances to the storage sites, often at too high a cost to the community.

Moreover, the problem of how the presence of a landfill can be integrated into the surrounding landscape in harmony with the population living in the area is not of minor importance.

The problem is particularly felt in all those areas with a potential for tourism, especially if the area is reduced, as typically is represented by the islands .

Such problems involve assimilable municipal and industrial solid waste, all non-hazardous but drastically poor, worthless and thus heterogeneous. The experience of these past fifty years teaches that any mechanical or thermal application to separate and/or destroy them energetically at 100% has only generated high costs for the community.

Summary of the invention

Therefore, it is object of the present invention to provide a plant and method for the biodigestion of waste, and specifically of the decomposable fraction of waste which, due to its cyclical nature, eliminates the need to search for new sites to be used as landfill.

Therefore, the present invention (hereinafter sometimes referred to as "MESB&B" for simplicity) has a basic philosophy which emerged from the awareness that such waste have minimal, if not zero, value and should be treated with a minimal energy of any kind in order to obtain an economic benefit, covering all costs of collection, creating jobs and protecting the environment .

Object of the invention

In a first object, the invention relates to a plant for the anaerobic digestion of waste biomass.

A method for waste management within such a plant is also described.

According to a further aspect of the invention, a method is described for biogas production, from which biomethane and/or electric and/or thermal energy can be obtained, as well as for obtaining a compost poor in organic matter but very rich in micro-biodiversity. Description of the drawings

Figure 1 shows the six-module configuration of the digester;

Figure 2 shows the twelve-module configuration of the digester;

Figures 3 and 4 show the configurations in figures 1 and 2 seen from the top, with the indication of the technological towers common to multiple modules, respectively;

Figure 5 is a diagrammatic representation of a portion of the digester comprising at least four modules and a technological tower common to them and the drainage channels of the process liquid conveyed to the respective tower are shown in a module;

Figure 6 shows the structure of the digester with the tarpaulins for covering the waste mass during the growing phase;

Figure 7 shows the structure of the digester which highlights the external openings of the technological tower, on the bottom the drainage channels of the process liquid conveyed towards the respective tower;

Figure 8 shows the structure of the digester which highlights the piping for recirculating the leached process liquid and for capturing the biogas;

Figure 9 shows the structure of the partially filled digester with the HDPE tarpaulin arranged on the upper part for the final covering at the end of the twelve-month growing period;

Figure 10 shows the digester, filled and covered with insulating material arranged underneath the final covering HDPE tarpaulin as shown in figure 9;

Figure 11 shows a further embodiment of the digester of the invention wherein there is the surface liquid recirculation network from the manhole arranged on top of the tower and underneath the final covering HDPE tarpaulin;

Figure 12 is a depiction of the last step of managing the biomass collected at the end of the 6 or 12 year cycle arranged heaped on the side of the digester to be dried by a special mobile machinery.

Detailed description of the invention

According to a first object, the present invention describes a plant for the multi-year cyclic management of waste biomass.

In the following description, reference will be made to waste management, according to the definitions provided hereinafter.

The waste mass described in the present invention will also be referred to as biomass (by virtue of the component of organic waste that it includes) and for present purposes, it may be of several types, such as: a) Biomass consisting of only wet kitchen waste collected separately in "door to door" manner (for the present purposes also referred to as a "pure wet waste") and represented by the organic waste of foods. In this case, it must be structured using a wooden portion, for example consisting of chipped pruning brushwood, for example, in a variable percentage from about 2% to 10% by volume, depending on its purity, i.e. depending on the percentage of dry component (paper and plastic, in particular) which acts as a physical structuring agent;

b) Biomass mechanically separate at the origin, which comprises about 15-25% of inert materials such as plastics, metals, paper, textiles, glass, wood (or wooden materials) .

In this case, it does not need to be structured.

c) Biomass mechanically pre-selected from municipal solid waste directly at the MESB&B center (the digester of the present invention) where the municipal waste is delivered, having already undergone macro- differentiation of plastics, paper, glass, metals in the citizens' home and/or at restaurants' and/or in the agroindustry (in practice, it is a biomass resulting from municipal solid waste from which plastics, paper, glass, metals have been separated) . In this case, the selection of the incoming waste will only be "macro" with a screen which allows recovering the noblest parts (glass, plastic and paper) which move from the screen to a belt where sorters take the best and the rest is grouped without structuring.

For the present purposes, the term duration "cycle" of the digester of the present invention means the period of time ranging from when a portion of waste is stowed to when the same portion of waste (of course converted by the process of the invention) is extracted from the digester .

The choice of the actual duration of the cycle depends on the following factors which should be taken into account :

agricultural energy; this factor also depends on the nature/origin of the incoming biomass

M Market and market needs when the invention is implemented

E Environment, meaning environmental healthiness.

As regards the "quantity" factor (Q) , this can range from about 50 to 250 tons per day (t/d) , where the possibility to absorb peaks up to 100/300 t/day must be contemplated.

"Space" (S) , on the other hand, must be within the parameters of about 8-16 tons per square meter (t/m²) , with a height of about 10-20 m.

Carbon (C) will vary greatly between being consumed to produce electric energy, thermal energy and biomethane, balancing such a need with that of obtaining agricultural energy.

It should be noted that Market (M) naturally tends to optimize the operating result without going against the interests of the Environment (E) .

Other factors, on the other hand, depend on environmental conditions and biophysical elements, such as:

pH

Natural corrective agents

Relative Humidity (R.H.)

Dynamics of liquid and gaseous flows Microbial load

Temperature

The pH of the system depends, in turn, on various factors, such as the quality of the substrate.

By natural corrective agents it is meant, instead, calcium carbonate or calcium dolostone.

With reference to the microbial load, it is meant not only the quantity of microorganisms capable of development, but also the type (quality) of the population, such as: aerobic and/or anaerobic.

As regards temperature, it is necessary to distinguish, in particular:

• aerobic bacterial population, which means those bacteria growing preferably in the first step of degradation in acidic pH condition.

• mesophilic bacterial population, which means those bacteria growing preferably at room temperature ranging from about +15°C to 55°C.

® thermophilic bacterial population, which means those bacteria growing preferably in warm environments from 55°C to 80°C.

As a further aspect, the concept of dynamism of liquid and gaseous flows is defined.

For the objects of the present invention, this aspect is of considerable importance, as will be described hereinafter .

The referenced digester (or biodigester) is in fact comparable to a landfill cell managed according to advanced mode.

In particular, the digester of the invention consists of a single module (shown in the figures with reference numeral 10) or of multiple modules, preferably implemented contiguously.

The configuration that includes multiple modules arranged next to each other allows implementing structures which are common to multiple modules, as will be described hereinafter.

To this end, according to a preferred aspect, a structure with at least four digesters is provided, arranged in two rows, which divide common structures arranged in the middle.

In order to manage a sufficient amount of biomass, the most common configuration is the one with 6 to 12 digesters, such as shown in Figures 1 and 3 or 2 and 4.

In the following description, reference will be made to "module", thereby indicating a single portion of the digester.

The digester, therefore, may consist of a single module or of a group of, for example, four, six, or twelve modules.

In one aspect of the invention, the group of 6/12 contiguous modules is delimited on three sides by a wall of about 15 meters, while it remains open on the fourth side.

Preferably, such walls are special anti-corrosion reinforced concrete with static and aseismic properties .

According to an aspect of the invention, the digester rests on a bottom which prevents the leachate and the process liquid from filtering in the underneath and surrounding ground and, thus, to the environment. Such a bottom is therefore preferably made of special anti- corrosion reinforced concrete (to withstand acids) and is also mechanically resistant, so as to withstand weights and scraping.

In a preferred conformation, such a bottom is not flat or, at least, not flat on its entire surface.

In fact, it is expected that the opening section of the digester is inclined downwards from the outside to the inside of the digester, so as to prevent leakage of material and process liquids, as defined hereinafter .

For example, starting from the outermost end and by a length of about 10-15% of the entire length of the digester, a lowering can develop from about 0.20 m to about 1 m up to reaching the bottom of the digester. In turn, such a bottom can be more or less lowered with respect to the surrounding ground.

The soil removed to obtain the lowering can be used for the construction of the external edges of the digester .

The purpose of the lowering is to hold the rain, or other rainwater, fallen on the biomass collected in the year and/or period of relevance, which, since waste leaches, is enriched with substances and microbial load reaching the bottom in the form of "process liquid".

According to a preferred aspect of the present invention, each module comprises means for draining the process liquid (see for example reference numeral 103 in figure 7 ) .

In particular, these are dedicated drains a few centimeters wide, and suitably long, even as much as the entire module, which develop across the width on the bottom of the module up to entering the technological towers.

As for example shown in figure 5, such drainage channels (reference 103) converge at a common point, for example represented by one or more of the ends or corners of the single module (technological towers) . Note that the central modules, as shown in figures 3 and 4, are provided with two towers on the closed side, while the two modules on the sides have a single technological tower.

The arrangement of the drains is such as to allow the flow in the direction of their technological towers also by virtue of the slope of the bottom of the digester .

According to a further aspect of the present invention, the digester includes means for capturing and collecting the gas developed from the biomass (see reference numeral 106 in Fig. 8 or in Fig. 11) .

Such means are represented by a system of perforated pipes which develops on the bottom of the digester and in the thickness of the collected biomass.

For example, a network of biogas collecting pipes may be expected to be arranged about every 3-5 meters, preferably about every 3 or 4 meters.

Moreover, the walls of the same technological tower may be provided with openings for further biogas collection (see reference numeral 104 in Fig. 7).

In order to prevent other material from passing through such openings, these can be closed by a suitable material, such as a filtering cloth (see reference numeral 110 in Fig. 7).

The gas will thus be collected, together with that from the network of perforated pipes, in biogas capturing well heads.

In particular, compared to gases which develop from waste in the prior art landfills, which comprise about :

60% methane

28% carbon dioxide

10% nitrogen

2% oxygen

in the case of the digester of the present invention, oxygen will not be more than about 0.5%, while nitrogen is reduced to about 4-6%, increasing the share of methane and carbon dioxide.

According to a further aspect, the digester of the present invention may further comprise means for recycling the process liquid (see reference numeral 105 in Fig. 8) .

In particular, such means comprise suitable piping which, starting from the technological towers, at which the drainage channels collect the process liquid into special wells (see reference numeral 101 in Fig. 5) , suitably travel, such as herringbone and on planes located at different heights, through the whole area of the digester; draught and relaunch (recirculation) pumps of the leachate are further provided.

In a preferred aspect, prior to recycling the process liquid, the portion deriving from a module of the digester is mixed with the portions coming from one or more other modules.

In this way, the composition of the recycled process liquid on the biomass is advantageously kept as constant and homogeneous as possible.

If deemed necessary in view of the methanogenesis state, prior to recirculation, the leachate and thus the process liquid may also further be energized by heating between 50-60°C (possibly by recovering the heat from the cogeneration motor, the biogas produces electricity) , by special natural substances to alter the pH or the carbon content thereof and/or it may be treated with appropriate microbial, bacterial and/or fungal preparations.

As described above, the digester of the present invention comprises structures called "technological towers" (indicated with reference numeral 100 in Fig. 3, 4 and 7) .

These are structures within which one or more of the following are at least partially accommodated: means for collecting process liquids, means for collecting gases, means for mixing process liquids, means for recirculating process liquids.

The technological towers, which can be also be made of reinforced concrete or other anti-erosion materials, can be provided for each module or they can be common to multiple modules.

As shown for example in figure 3, a technological tower can be made at the point of convergence of 4 different modules.

In order to allow their maintenance, such structures may be provided with man-pass hatches (indicated with reference numeral 102 in Fig. 5 and 11) .

In a preferred embodiment of the invention, the described digester may comprise, possibly also partly accommodated into the "technological towers" themselves, means for activating the biomass.

Such means may be represented by a substance or mixture of substances able to stimulate, and possibly also accelerate, the degradation of the biomass.

An example of bioactivant mixture is represented for example by a mixture such as the product EZYVEBA (produced by MARCOPOLO) , consisting of a multxmicrobial fungal and bacterial consortium.

For the present objects, the digester of the invention may further comprise means for the thermal insulation and for keeping the temperature within the waste mass in the digester.

To this end, an appropriate waterproof sheath will be used in order to isolate the underlying material from the outside environment, and possibly also waterproof it.

Therefore, depending on the needs, a PE HDPE sheath may be used, for example, beneath which a 30-40 cm high layer of fibers recycled from wooden chips may be arranged .

According to a preferred aspect, the waste mass is kept at a temperature of about 35-40 °C.

In one aspect of the invention, the re-use of process liquid originated by the rain entering the digester during the year of growing with the collection of the waste is described.

Such a leachate is kept at a temperature of about 40°C, pretreated to obtain a process liquid with the proper pH and possibly also enriched through the inoculation of microorganisms, for example thanks to the ENZYVEBA consortium (produced by MARCOPOLO) .

The leachate thus pretreated obtained from the digester described above to produce electric energy, thermal energy and/or biomethane, is used as a process liquid to make the digester dynamic, combining the values of H, temperature and humidity.

According to a particular aspect of the present invention, it is possible to add organic non-polluted liquids to the process liquid.

More in detail, these are:

organic liquids from agro-industrial activities; and/or

- organic liquids from livestock activities; and/or

- organic liquids from the food industry.

This is preferably possible to up to 10% by volume of the digester module.

This possibility was tested from the data of a research conducted by Marcopolo (and called DISC-JET) , which included adding up to 10% of organic non- polluted liquids to rainwater, which on average accounts for 6%-8% by volume of the digester.

This has two main advantages: on the one hand, not producing liquids which require disposal, on the other, contributing to sustaining the economy of the companies producing such liquids, which activity will better integrate with the digester of the present invention .

This practice, which can be a useful alternative in areas or periods characterized by scarce rainfall, has surprisingly proven to increase biogas production by about 25-30%, with a remarkable improvement of the final composted product.

To this end, drafting pumps may be provided able to draw the process liquid conveyed by the drains and collected in the special collection tank inside the technological towers.

In this respect, one or more of the following means can be used: use appropriate microbial, bacterial and/or fungal preparations aimed at promoting methanogenesis , use of preparations for changing the pH, temperature change.

In another aspect thereof, the invention relates to a method for waste management within the plant described above .

In particular, such a method comprises the steps of A) preparing the biomass

The mass of municipal solid waste is treated at the inlet of the B&B plant of the present invention with a primary screening and selected so as to separate glass, plastic, paper, metals and wood (or wood-based materials) which are directed to separate and dedicated recycling processes, leaving the smaller fractions of such inerts into the mass (therefore, the remaining portion is added to the wet fraction of the waste) . B) stowage

The waste is collected according to a specific pattern in batches.

For example, they can be made on a daily basis by growing them with batches of about 16.5 X 16.5 meters, about 1 meter high, preferably properly compacted.

According to the present invention, the completion of one module of the digester is achieved within a year. In the case of six digester modules, the cycle lasts six years and therefore, when the sixth digester module is filled at the sixth year, the first digester module is emptied in the same year, thus continuing the cycles, the seventh year returning to fill the first module.

In a preferred aspect of invention, at the end of each working day, the batch is covered with a tarpaulin, preferably non-woven fabric, to prevent the material from flying away and the gases produced and not captured from being released to the environment.

Moreover, the non-woven fabric tarpaulin may be sprayed with an appropriate preparation called Enzyveba RC600 (produced by Marcopolo) in order to eliminate or reduce unpleasant odors.

To this end, it is possible to use a mixture comprising: the powder product ENZYVEBA NK12 in the amount of about 10-50 grams, and preferably about 15- 30 grams, per tons of waste.

In particular, such a powder is put in water, soaked for 48 hours and then sprayed on the surface of the waste collected during the day.

At the end of the filling year, the module is covered as described above in order to keep the temperature as constant as possible and prevent the entry of rainwater, as shown for example in Figure 9, insulating the digester as shown for example in Figure 10, wherein reference numeral 107 indicates the layer of insulating material, such as recycled fibers.

According to the present invention, up to about 110, 000 tons of biomass may be collected over one year .

C) activation

From the second year, the step of activating the stowed waste begins.

To this end, the mass with the pretreated leachate which becomes process liquid is treated.

In particular, the rainwater which fell during the module filling year washes the waste mass, thus enriching with all the chemical and biological substances present in the waste.

In a preferred aspect of the invention, such a liquid can be further properly treated and activated, for example with suitable microbial, bacterial and/or fungal preparations, aimed at promoting methanogenesis, modification of pH and of temperature (as described above) .

As already described above, moreover, the process liquid is obtained from the leachate collected, when possible, from different portions of the module or from different modules so as to homogenize the characteristics and the microbiological and chemical composition .

Moreover, one of the suitable preparations described above may be used to accelerate the activation of the biomass .

D) biogas capture

This step starts approximately already after the first six months of collecting and continues in parallel throughout the management period of the digester.

E) co-generation step

During this step, the production of electric energy and thermal energy takes place starting from the biogas captured, as shown for example in Figure 8 (wherein reference numeral 106 indicates the biogas capturing and conveying piping) .

In particular, greenhouses, private houses and small industries can take advantage of this heat and energy source .

In a further aspect of the invention, the installation of a biogas (methane) recovery system may be provided, to be used for transport or co-generation,

f) emptying

In the last step, the digester of the invention is progressively emptied, each module within a year.

In particular, the emptying takes place at the same rate, in terms of amount of waste by weight with respect to time, used for the previous filling thereof and, therefore, the same amount of biomass collected each day will be collected on a daily basis (the daily batch, as indicated with reference numeral 108 in Fig. 9) .

To this end, the waste biodegraded over the previous five/ten years is carried to a dedicated yard outside the digesters (fig. 12) and placed stacked in the appropriate lane to be subjected to aeration in order to reduce the humidity thereof which, at the end of the digester cycle, is about 80-90%.

Such a process can be implemented, for example, through the use of aeration with hot and dry air at 40°C in appropriate composting yards (such as shown for example in Fig. 12), wherein the biomass, sheltered from the rain and near the wall of the digester, can be naturally aerated and subjected to periodic upturning, for example every 2 or 3 months. In this way, it is possible to obtain a final relative humidity of 50%, thus falling within the European parameters of mixed soil improving composts.

A portion is thus obtained from this step which is represented by soil usable as compost for energy cultivation .

Moreover, the dry material initially not separated in the initial screening (plastic, glass, metals, paper, wood or wooden materials) may also be recovered.

Such a dry portion can therefore be used as fuel in suitable gasifiers (pyrolysis) , obtaining ashes which can be used in construction (plastic cement or sound and/or thermal insulation panels) or sent to dedicated landfills .

g) use of the resulting compost

The resulting compost can be used for non-food energy cultivation .

h) Control of the digester and biokinetic correction

In a preferred aspect of the invention, during any of the steps described above, checks may be carried out on the liquid and gaseous flows and on the biomass to check the carbon consumption and the methanogenesis pattern .

To this end, a rate of the leachate or biogas may be suitably collected and, through special analyzers, subjected to checks on the composition.

The analysis, in particular, may be carried out continuously or in sample batches.

From the results of the analysis it is possible to understand how the biodigestion process is proceeding and, therefore, implement any necessary corrective behaviors to control the methanogenesis, such as:

- changing the recycling speed of the leachate;

- changing the amount of recycled leachate;

changing the treatment with microbial, bacterial and/or fungal systems;

- changing the pH;

- changing temperature.

Moreover, the data collected are used to decide the best destination of the biomass extracted from the digester at the end of the cycle, which must contain a sufficient amount of carbon for agronomic crops.

According to the present invention, the method described can be carried out over a period of five or ten years.

The last and additional period, on the other hand, is dedicated to emptying the biodigester. EXAMPLE

The comparison between a traditional landfill and a MESB&B plant according to the present invention, which covers an area of 90, 000 m ² (9 ha) shows that the cyclical nature of the plant is able to manage the waste generated daily by about 280,000 inhabitants (equal to approximately 210 tons/day and about 75,000 tons/year) equivalent to approximately 450,000 tons in 6 years .

Over a 30 year period, therefore, up to 3, 000, 000 cubic meters (or 2,700,000 tons) may be treated in 6 consecutive cycles.

A traditional landfill could collect the same amount of waste in about 10 years, followed by 30 years of post-management but requiring as much as 340,000 m² (four times the area required for the plant of the present invention) .

The several advantages offered by the present invention will be apparent to the man skilled in the art from the description above.

Further advantages will be identified over time, such as the utility of the method and the plant described. Among the first ones that can be mentioned, without wishing to apply any special logic or priority, is the possibility of reusing the module every 5 or 10 years to achieve zero waste, i.e. the recovery of all the matter previously treated and stored.

This allows the huge advantage of eliminating the search for new sites to use as a landfill or waste disposal center which, as stated above, is a problem particularly felt in tourist areas, especially islands .

In the traditional landfill example shown above, at the end of 10-year filling period, a new landfill should be prepared, occupying a ground area of equal to additional 340,000 m².

The possibility of covering the storage site, due to the fact that the modules are covered and grass, plants and flower bushes can then be grown on its surface, allows for better integration into the landscape, within which it may represent a real green oasis .

From an economic point of view, moreover, the plant described allows a good "economic return"; in fact, the investment/profit ratio is constantly improving and from the 4th to the 6th year it enters the profitability stage, with profits growing exponentially after the 5th and 10th year when construction works are completed and the equipment and plants are completed.

The cost for the construction of the plant, in fact, is significantly lower than that required for traditional systems.

As a result, the cost of waste management is 3 to 5 times lower than the most advanced systems (such as selection and composting plants, as well as incinerators) towards which the cost is reduced to about one-third and is in any case up to 1.5 times less expensive than the traditional landfill, which is considered as the most cost-effective management method .

Moreover, such a cost is further reduced with each cycle of management, while the cost of managing a traditional landfill, in the best case, remains constant .

It was surprisingly found that the plant of the invention significantly reduces odors, up not to emitting any odor and/or dispersion of waste and parts of waste; in this way, accepting the presence of the biodigester by the population may be easier.

Moreover, it was verified that at the end of the process there is no production of leachate, which must undergo purification.

This allows a clear saving of time and money and reduces the possibility of toxic or malodorous environment-polluting vapors developing from the leachate .

The shorter distance required, or at least tolerable, from cities allows reducing the time and costs of waste transportation, with a first immediate positive result of the invention.

Other productive activities may therefore be installed next to the plant, such as companies or crops, without the well-known obstacles or diffidence existing today. A further advantage offered by the present invention is the ability to implement the digestive modules with current materials available anywhere, such as for example anticorrosion reinforced concrete, and capable of lasting over time, even up to 250 years, until the concrete containing structures (bottom and walls) allow it.

Claims

1. A biodigester for the multi-year management of a waste biomass comprising means for recirculating the process liquid, wherein such a process liquid comprises the liquid leached from said waste.

2. A biodigester for the multi-year management of a waste biomass according to the preceding claim, further comprising means for draining the process liquid from said mass.

3. A biodigester for the multi-year management of a waste biomass according to claim 1 or 2, further comprising means for capturing or collecting the gases developed by said waste biomass.

4. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims, further comprising means for treating said waste with appropriate microbial, bacterial and/or fungal preparations.

5. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims, further comprising means for the thermal insulation and/or for keeping a specific temperature of/in said waste mass.

6. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims, further comprising means for mixing the process liquid before it is recirculated.

7. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims, wherein said process liquid comprises rainwater .

8. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims, wherein the means for recirculating the process liquid comprise means for distributing said liquid in the mass and/or on said waste.

9. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims, wherein said biodigester comprises one or more modules .

10. A biodigester for the multi-year management of a waste biomass according to the preceding claim, wherein said modules are in a number of 6 or 12 or multiples of six.

11. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims, comprising a bottom able to prevent the process liquid from filtering into the surrounding environment and/or able to withstand loads and/or scraping .

12. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims, wherein said means for draining the liquids comprise one or more channels located on the bottom of the digester.

13. A biodigester for the multi-year management of a waste biomass according to any one of claims 9 to 12, wherein said means for recirculating the process liquid comprise means for collecting and mixing the process liquid coming from different modules.

14. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims 11 to 13, wherein said bottom is inclined so as to prevent the process liquid from leaking from the biodigester .

15. A biodigester for the multi-year management of a waste biomass according to any one of the preceding claims, wherein one or more of the following:

- means for collecting the process liquid,

- means for capturing and collecting the gases,

- means for mixing the process liquid,

- means for recirculating the process liquid,

are at least partially accommodated within the same structure .

16. A biodigester for the multi-year management of a waste biomass according to the preceding claim, wherein said structure is common to two or more modules .

17. A method for the cyclic multi-year management of a waste biomass in a biodigester comprising one or more modules, each containing a mass of collected waste, comprising the step of activating said mass by means of a treatment with the process liquid, said liquid comprising the liquid leached from said waste biomass.

18. A method for the cyclic multi-year management of a waste biomass in a biodigester according to the preceding claim, wherein said process liquid is collected by two or more of said modules and possibly mixed prior to said activation.

19. A method for the cyclic multi-year management of a waste biomass in a biodigester according to the preceding claim 17 or 18, wherein said process liquid is activated by means of one or more of the following actions :

using microbial, bacterial and/or fungal preparations aimed at promoting methanogenesis ,

- using preparations for changing the pH;

- changing the carbon content;

- changing temperature;

- adding organic liquids selected from: i) organic liquids from agro-industrial activities; and/or

ii) organic liquids from zootechnical activities; and/or

iii) organic liquids from the food industry.

20. A method for the cyclic multi-year management of a waste biomass in a biodigester according to the preceding claim 19, wherein said organic liquids are added to said waste within a module up to 10% by volume of the module of the digester.

21. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of claims 17 to 20, wherein said step of activating further comprises one or more of the following treatments of the waste mass:

- treating said mass with a microbial bacterial and/or fungal preparation;

- adjusting the pH of said mass;

- adjusting the temperature of said mass.

22. A method for the cyclic multi-year management of a waste biomass in a biodigester according to the preceding claim 19, wherein said process liquid is heated to a temperature of about 50-60°C.

23. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 22, wherein said waste mass is collected over a period of about a year within each module .

24. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 23, wherein at the end of the step of collection of the biodigester, the waste mass is covered with a layer of insulating and/or waterproof material.

25. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 24, wherein said material is treated with a product which contributes to eliminating or reducing the formation of smell.

26. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 25, wherein said collected waste mass is kept at a temperature of 35-40°C.

27. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 26, comprising the further step of capturing and collecting gases developed from the collected waste mass.

28. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 27, wherein the process liquid is recirculated on top or into the collected waste mass.

29. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 28, comprising the further step of progressively emptying the biodigester at a speed (amount of waste/time) equal to that of filling each module.

30. A method for the cyclic multi-year management of a waste biomass in a biodigester according to the preceding claim, comprising the further step of reducing the relative humidity of the waste mass emptied from each module, obtaining a dry residue.

31. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 30, wherein the percentage of relative humidity at the end of said step is about 50%.

32. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 31, comprising the further step of producing electric energy and/or thermal energy and/or methane starting from biogas.

33. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 32, comprising the further step of producing one or more of the following: electric energy, thermal energy, soil or compost starting from the dry residue of said waste.

34. A method for the cyclic multi-year management of a waste biomass in a biodigester according to any one of the preceding claims 17 to 33, wherein said biomass comprises :

- a biomass made of only wet kitchen waste collected separately and represented by the organic waste of food, to which a structuring portion of a wooden organic constituent may optionally be added, in a percentage of about 2% to 10% by volume; or

a biomass mechanically separated from municipal solid waste and comprising about 15-25% of inert materials such as plastics, metals, paper, textiles, glass, wood or wooden materials; or

- a biomass obtained from municipal solid waste from which plastics, paper, glass, metals, wood or wooden materials have been separated.