Biological-Origin Waste Materials

Field of the Invention

The present invention relates to the composition of a biodegradable mixture of waste materials of primarily biological origin containing biogenic elements, such as carbon, hydrogen, oxygen, sulphur, and nitrogen, intended for the production of fuel for direct combustion, located for the production start in conventional atmospheric gases. It also relates to a method for fuel producing from a biodegradable waste material mixture of biological origin.

Background of the Invention

There are several ways to dispose of or exploit waste materials of biological origin that are currently known. The best known method is composting, which is an aerobic process of decomposition of plant-origin material, proceeding under certain conditions with the help of microorganisms. The resulting product is usually used for fertilization or as part of a plant growing substrate. The disadvantage of this process is that harmful substances are not removed from the initial mixture, for example, petroleum substances, medication and drug residues, hormones, heavy metals, endocrine disruptors, poisons, dyes, etc.

In nature within a long-term process, so-called carbonation (or ulmification) of plant-material mixture can be observed, resulting in combustible material such as peat or coal. Due to a very long process, however, the practical usage of the disposal of bio- waste is difficult to use.

There is a continuing need for the disposal or recovery of bio- waste, substances hard-to-usable in their original form and dangerous or hazardous substances. A process of chemical and biological heating, which results in a readily combustible material with significant calorific value and good fuel properties, seems to be suitable. However, the process start and intensity are very dependent on the chemical, biological and physical properties of the initial mixture. This seems to be a major problem, because the process does not take place in the desired intensity or range at inappropriate mixture composition.

The invention aims to provide a composition and properties of the initial mixture of biological-origin waste materials and create such conditions that a process of chemical and biological heating may be started without delay and with sufficient speed, resulting in a material with neutralized or destroyed pollutants and a high energy value, usable as fuel for direct combustion.

Summary of the Invention The mentioned task is fulfilled by the invention, which is a mixture of biological-origin waste materials, biodegradable, containing the biogenic elements, such as carbon, hydrogen, oxygen, sulphur and nitrogen, for the production of direct combustion fuel, located in an aerobic environment in the presence of air oxygen and other atmospheric gases. The invention is based on the fact that the mixture contains initial humidity of 40-70% by weight of water and at least 25% by weight of organic substances, while the total weight of the mixture is at least 3,000 kg and is piled up to a height of max. 3 m to a vertical axial cross section shape in the form of an isosceles or equilateral triangle or trapezoid or rectangle. The mixture is composed of at least two basic groups of substances: for one thing, succulent substances having a water content of 5-98% by weight as a source of inoculum of microflora and water, and for another, non- succulent substances in a quantity of at least 15% of the total weight of the mixture as a source of reducing agents and structural substances. The succulent substances are meant at least one type of sludge-kind material that is composed of a liquid phase and a solid phase dispersed in the liquid phase. The non- succulent substances are meant materials containing cellulose with a fraction of 15-750 mm. The succulent substances are sludge from municipal wastewater treatment plants and/or sludge from industrial wastewater treatment plants and/or less sludgy materials. Non-succulent substances are lignocellulosic materials and/or packaging and their parts from commercial and/or communal areas and/or other materials containing cellulose. For the invention, it is also important that sludge from municipal wastewater treatment plants is selected from the sludge group: primary sludge, secondary sludge, tertiary sludge, raw sludge, anaerobically stabilized sludge, aerobically stabilized sludge, chemically stabilized sludge, physically stabilized sludge, and dewatered sludge. The sludge from industrial wastewater treatment plants is selected from the sludge group: sludge from pulp and paper production, sludge from plywood production and waste fibres from fibreboard production, manure, excrements, litter, and sludge from other production. Less sludgy materials are selected from the material group: cadavers, silage, haylage, fruits, vegetable fats and oils, residues from agar and gelatine production, culture medium of biotechnological production, biogas plant products, aquatic plants and animals, food wastes and surpluses.

The lignocellulosic materials are dendromass and/or phytomass. Packages and their parts from the commercial and/or communal areas are selected from the material group: paper, cardboard, paperboard, beverage and food packaging of composite materials, such as TetraPacks. Other materials are selected from the material group: banknotes, pulp products.

For the waste material mixture of the invention, it is also essential that in order to achieve the maximum effect, it is piled up into a substantially pyramidal shape with a crest or peak height of at least 1.5 m and a maximum of 2.5 m, while the total mixture weight exceeds 3,000 kg, preferably 10,000 kg.

Water content of the mixture is advisable to be 50-65% by weight. At least a portion of the succulent substances may be replaced by excipients, as an agent enhancing reactive surface and/or a heat-insulating agent. These excipients are constituted by auxiliary lignocellulosic material and/or mining sludge and/or other wastes. Auxiliary lignocellulosic material is selected from the material group: sawdust and shavings, straw pulp, bones, fruits and their parts and shells, chaff and husks, groats, bran, grass, aquatic biomass; other waste is selected from the material group: bottom sediments, rubber products, and tanning waste.

The method of fuel production from biological-origin waste materials is based on the fact that individual components are deposited into layers under normal atmospheric conditions to form the mixture, while the individual components are selected and/or added according to the humidity content, the initial humidity of the mixture being 40-70% of mixture weight, while the resulting looseness of the mixture allows for the independent keeping of the piled up shape. Subsequently, they are mechanically mixed into a homogeneous composition and uniform distribution of the humidity, and they are piled up as a mixture into a shape with a maximum height of 4 m, which drops down to the required height of 3 m after sinking. Then, surface desiccation of the mixture related to the mixture flings is observed, where the mixture is mixed mechanically and/or pneumatically and re-homogenized if the flings occur. At the same time, leakages from the lower mixture part are monitored, where, if any leakage occurs due to an excessive sinking or humidity permeation into the lower layer, the mixture is mechanically and/or pneumatically mixed and re- homogenized. At the same time, the temperature progress is monitored at least 0.8 m above the base and at least 0.8 m below the mixture surface, while the mixture is re-mixed in the case of premature temperature stagnation, and the process ends after stopping the temperature fluctuations at a stable temperature of maximum 40 °C.

The advantage and the higher effect of the invention are not only the obtaining of fuel with significant calorific value, but in particular the neutralization and/or decomposition of the pollutants present in the initial mixture. Within the process of chemical and biological heating itself and transformation of the starting substances and, subsequently, during controlled combustion of the resulting substance - the fuel, the majority of undesirable substances is finally and completely destroyed. This minimizes their impact on the environment and, in addition, a usable fuel for direct combustion is obtained.

Overview of drawings

The mixture composition of the invention and the method of component processing is schematically illustrated in the Fig. 1. The Fig. 2 shows a diagram of the piled up mixture according to a technical solution in the phase after process- start-up. The Fig. 3 shows in detail a portion of the mixture with reaction zones and microorganisms after process-start-up.

The Fig. 2 and Fig. 3 show a natural process schematically in accordance with the conditions of the invention. The area A is a passive zone, the arrow B shows air transfer through the mixture, the arrow C is natural leakage of thermal energy from the zone of heated area, and the arrow D is natural leakage of thermal energy from the intensive heating zone. The areas E are single mixture particles, F is the surface particle humidity, G shows functional microorganisms on particle surface, and H is space between the particles, where the most important reactions occur.

Embodiments of the invention

Before describing a few examples of a specific mixture composition according to the technical solution, the basic characterization of the chemical and biological heating process is given.

For the spontaneous start of the process, a mixture of materials with certain biological, chemical and physical properties must be created. The mixture or its components are of biological origin and biodegradable, containing biogenic elements, such as carbon, hydrogen, oxygen, sulphur, and nitrogen. The materials may not be precisely defined but must meet certain parameters. In particular, following is important for the process itself: - Content of organic and inorganic components

- Chemical and biological properties of the components

- Percentage of individual components

- Content of bound and free humidity in the mixture

- Size of individual particles

- Percentage of smaller and larger particles

- Total volume and shape of the mixture

- Bulk density

- Porosity

- Thermal insulating properties of the mixture

- Concentration of gases

- Duration of the process

- Conditions in the surrounding atmosphere

During the process, the thermal fission of the bonds takes place in the components and their chemical composition changes to form other substances. The structure and construction of materials vary depending on the size of pores and capillaries, affecting the transfer of oxygen, heat and gas penetration. Particular shapes and sizes of particles, such as dimensions, number of edges and rounding, different angles on the particles, influence the ongoing processes. The process is faster and more intense for materials with a rough and porous surface than for materials with smooth particles. Thermodynamic properties, such as the mass and heat capacity of materials, thermal conductivity, heat transfer coefficient, etc. are also important.

For the own technical solution, it is essential to create the appropriate conditions for initiating and maintaining the above process. This is achieved by suitable mixture composition and by ensuring its important parameters.

The process starts immediately or after a very short period of time from formation of the basic mixture, first in individual centres, which are gradually increasing and expanding to the whole mixture. The process runs automatically in each stage, evolving over time. Since the very nature of the chemical and biological heating process cannot be a subject of the technical solution, its detailed explanation is not important here.

However, the important thing is how to ensure that the process proceeds efficiently, or what steps to do to achieve the process optimization. To do this, it is necessary to:

1. Monitor the composition of the mixture with a total organic content of at least 25% by weight, preferably above 35% by weight.

2. Achieve correct chemical and biological property of the mixture in such way that it is composed of at least two basic groups of substances: for one thing, succulent substances 1 having a water content of 5-98% by weight as a source of inoculum of microflora and water, and for another, non-succulent substances 2 in a quantity of at least 15%, preferably above 25% by weight, of the total weight of the mixture as a source of reducing agents and structural substances. A portion of the non-succulent substances 2may be replaced by excipients 3, as an agent enhancing reactive surface and/or a heat-insulating agent, i.e. to optimize the physical properties of the mixture.

3. Achieve the initial humidity of the mixture after mixing before starting the process of 40-70% by weight of water, preferably 50-65% by weight.

4. Ensure and maintain as much thermal energy as possible, changing at different stages of the process. However, the rule that cooling due to the surrounding environment must be less than warming due to the ongoing process applies. Ideal process development occurs when the temperature rises to about 50-55 °C within 72 hours of formation, and/or when the temperature rises by 5-7 °C in 24 hours. The highest process intensity is get at temperature above 60 °C. It is desirable for the mixture temperature to exceed 60 °C within 96-120 hours from the mixture formation, because the individual events proceed optimally under these conditions. As the temperature rises, the speed and intensity of the reactions increase. Upon raising the temperature by 10 °C, the reaction rate increases 2-times to 4-times.

5. Ensure the correct amount of oxidizing and reducing agents in the mixture. The oxidizing agents induce the process and maintain it, the reducing agents oxidize during the process. This technical solution it is characterized by use of the most available oxidizing agent, which is air oxygen. It is desirable for it to make approximately 21% of gaseous mixture component volume in the mixture with other atmospheric gases. To keep the air oxygen amount in the mixture, porosity and bulk density of the mixture, its shape and height, as well as the size of the individual fractions, the ratio of the proportion of larger and smaller particles, and the variety of particle shapes should be adapted. Larger amount of small particles increase the surface for reaction, larger particles ensure mixture porosity.

6. Adjust the size, structure, shape and amount of particles before mixing the initial material mixture. For the process, it is important to ensure and maintain its physical properties in particular. The minimum weight should be at least 3,000 kg, but preferably more than 10,000 kg. The ideal shape of the piled up mixture to achieve the maximum effect is essentially a pyramidal saddle shape with a crest or peak height of at least 1.5 m and a maximum of 2.5 m with a vertical axial cross section in the form of an isosceles or equilateral triangle or less preferably in the form of a trapezium or rectangle. Such shape and weight of the mixture ensures sufficient penetration for atmospheric gases, there are no excessive mixture sinking, while maintaining the desired mixture bulk density and porosity and its thermal insulating properties. Ideally, a layer of 1.5 to 2.5 m usually isolates very well the emerging centres of the self-heating process. To achieve the maximum effect, the layer should not be more than 3 m. In the case of layers higher more than 3 meters, the mixture becomes more compact due to its own weight, the porosity is reduced, and the oxygen content decreases. With regard to the process course, it is important to note that in many cases it is advisable to remove produced gases, in particular NH3, H2S, CO2, and CH4, or promote their releasing in order to optimize the process, otherwise, they may affect negatively the transformation processes.

When regrouping the mixture, additional substances can be added to improve the parameters to positively influence the process, speed it up, and make it more efficient.

Termination of the process results in a spontaneous decrease in the mixture temperature, the change in the original humidity, structure and appearance.

For the groups of substances referred to in the point 2:

There are practically three groups of substances, namely succulent substances 1, non-succulent substances 2, and excipients 3.

The succulent substances 1 are at least one type of sludge-kind material that is composed of a liquid phase and a solid phase dispersed in the liquid phase. They are sludge from municipal wastewater treatment plants la and/or sludge from industrial wastewater treatment plants lband or less sludgy materials lc.

Sludge from municipal wastewater treatment plants la is selected from the sludge group: primary sludge lal, secondary sludge la2, tertiary sludge la3, raw sludge la4, anaerobically stabilized sludge la5, aerobically stabilized sludge la6, chemically stabilized sludge la7, physically stabilized sludge la8, and dewatered sludge la9.

The sludge from industrial wastewater treatment plants lb is selected from the sludge group: sludge from pulp and paper production lbl, sludge from plywood production and waste fibres from fibreboard production lb2, manure, excrements, litter lb3, and sludge from other production lb4.

Less sludgy materials lc are selected from the material group: cadavers, silage, haylage lcl, fruits lc2, vegetable fats and oils lc3, residues from agar and gelatine production lc4, culture medium of biotechnological production lc5, biogas plant products lc6, aquatic plants and animals lc7, food wastes and surpluses lc8.

The non-succulent substances 2 are materials containing cellulose with a fraction of 15-750 mm. They are lignocellulosic materials 2a and/or packaging and their parts from commercial and/or communal areas 2b and/or other materials 2c containing cellulose.

The lignocellulosic materials 2a are dendromass 2al and/or phytomass

2a2.

Packages and their parts from the commercial and/or communal areas 2b are selected from the material group: paper 2bl, cardboard 2b2, paperboard 2b3, beverage and food packaging 2b4of composite materials, such as TetraPacks. Other materials 2c are selected from the material group: banknotes 2cl, pulp products 2c2.

These excipients 3 are constituted by auxiliary lignocellulosic material 3a and/or mining sludge 3b and/or other wastes 3 c.

Auxiliary lignocellulosic material 3a is selected from the material group: sawdust and shavings 3al, straw pulp 3a2, bones, fruits and their parts and shells 3a3, chaff and husks, groats, bran, 3a4grass 3a5, aquatic biomass 3a6.

Other waste 3c is selected from the material group: bottom sediments 3c 1, rubber products 3c2, and tanning waste 3c4.

All the materials should be suitably modified prior to mixing. The succulent substances lare usually a subject of drying or desiccation, sedimentation or other kind of component separation, drainage, sterilization or pasteurization, etc., as necessary. The non-succulent substances 2 are usually mechanically treated, crushed, split, cut, milled, and sorted. Excipients 3 are modified chemically and/or mechanically by their nature, for example through drying and desiccation, draining, separating, sanitization, etc.

After treatment, each component is weighed, dosed and mixed in a relatively homogeneous bulk mixture. This is pile up into the appropriate shape of the pyramid mentioned above or saddle-shaped with the ridge line. Under normal atmospheric conditions, the desired process is started practically within a few hours if the mixture composition and parameters are as per the invention.

During the process, it is possible to check the parameters such as humidity and temperature, or the presence of various gases, etc. If necessary or to speed up the process, it is advisable to rearrange the mixture, mix it, or add additional substances to adjust the parameters. The result is a combustible material - a fuel of good calorific value, which can be directly combusted for subsequent heat or electric energy production. The whole process is characterized by a synergistic effect in gaining the energy potential of the mixture. The calorific value of the final fuel is higher than the sum of the calorific values of input materials.

Mixture handling and method of its creation in practice is usually such that the input components, for which at least 80% of resulting mixture weight form fractions of maximum of 750 mm, are piled up to a height of maximum of 4 m, which achieves the required height of 3 m after homogenization by mixing and sinking. The advantage of the triangular or trapezoidal vertical cross-section of the mixture is based on the fact that air is intake from the surrounding environment to the mixture base. As the air passes through the mixture core, it is heated intensely and the heated air exits and escapes through the mixture peak, causing movement through the mixture.

When creating a pile, the components are combined and stacked into layers. The total humidity is monitored taking into account that the resulting starting humidity of the mixture is 40-70% by weight of the mixture. In addition, the resulting looseness of the mixture enabling independent holding of the piled- up shape is monitored. The components are mechanically mixed into homogeneous composition and even distribution of humidity, and they are piled up as the mixture into a shape. If the shape is sufficiently homogeneous after the pilling up the components and holds its shape due to the appropriate looseness, another mixing is not necessary. Independent holding of the shape is a sign of proper mechanical composition with appropriate humidity. Then, surface mixture drying is monitored in relation to mixture flings where the mixture is mechanically and or pneumatically mixed and re-homogenized, if any fling occurs. The flings occur when the mixture is too dry on its surface. In addition, leakages from the lower mixture part are monitored, where, if any leakage occurs due to an excessive sinking or humidity permeation into the lower layer, the mixture is mechanically and/or pneumatically mixed and re-homogenized, the humidity is distributed into the entire volume, the mixture is aerated, the oxygen consumed intensively through the process is added. Too sunk, possibly excessively humidity-soaked lower layer would cause the gaseous component necessary for the process to be limited. At the same time, the temperature progress is monitored at least 0.8 m above the base and at least 0.8 m below the mixture surface. The temperature must be measured regularly, optimally daily, or continuously using special probes. The basic monitored parameter is the steadily rising trend of temperature. It is not as important as how fast the temperature rises, but it must be increased. Increase in the temperature is not infinite, but if stagnation or temperature drop is detected, the mixture is necessary to be remixed. The mass automatically cools, but the temperature increases again due to ongoing reactions. In this way, the mixture is repeatedly heated and cooled, resulting in a typical tooth-like progress of the temperature. At the beginning of the process, changes are very significant, but they diminish over time and fluctuations become flat, which is a typical feature of the gradual depletion of usable energy. Normally, temperatures above 55 °C are reached during the process; ideally, the temperature rises above 70-75 °C, sanitizing the mixture.

Through repeated temperature increasing and subsequent cooling, which is ensured by mechanical and/or pneumatic mixing, the appropriate values are achieved to keep the process working:

- The oxygen content in the gaseous component of the mixture does not fall below 12% of the gaseous component volume.

- The C02 content in the gaseous component of the mixture does not exceed 30% of the gaseous component volume.

- The nitrogen content in the gaseous component of the mixture does not exceed 25% of the gaseous component volume.

- The moisture content in the mixture is uniform throughout the whole volume.

- Due to the structure, air pockets, where the most intense reactions take place, are formed.

If the temperature after repeated mixing does not rise above 40 °C when measured, it is a sign of depletion of usable energy for the mixture processes and the process ends. In this case, the mixture has reached its maximum capacity and can be used as fuel. It is not unavoidable to always wait for this state to be reached, the process can be terminated earlier, but the fuel properties will be worse.

Before using, this fuel can be sorted, crushed, complemented by some additives to improve the parameters, or dried and granulated, extruded, etc. According to the character of the input materials, especially with regard to the pollutants contained therein, an analysis is carried out for the control of chemical and physical fuel properties and for the control of elimination of pollutants, ideally for their complete degradation to non-hazardous substances.

Specific examples of mixture composition:

Example 1:

Mixture composition of total weight of 126,000 kg:

43,000 kg of anaerobically stabilized sludge la5 from a wastewater treatment plant

10,000 kg of biogas plant product lc6 - digestate

34,000 kg of phytomass 2a2 - wheat straw

13,000 kg of dendromass 2al - wood chips

In order to adjust the parameters, following was added after 10 days: 6,000 kg sawdust and shavings3al - wood sawdust 20,000 kg of dendromass 2al - wood chips

Initial humidity of the mixture: 62.3% by weight

Process of chemical and biological self-heating took 29 days.

Humidity before combustion of the resulting material - fuel: 33.6 % by weight

Calorific value: 9.52 MJ/kg. Example 2:

Mixture composition of total weight of 108,000 kg:

26,000 kg of raw sludge la4 from a wastewater treatment plant

18,000 kg of mining sludge 3b

20,000 kg_of phytomass 2a2 - wheat straw

2,000 kg of mowed grass 3a5

30,000 kg_of dendromass 2al - wood chips

4,000 kg of bran 3a4 - cereal husks

Initial humidity of the mixture: 64.2% by weight

Process of chemical and biological self-heating took 19 days.

Humidity before combustion of the resulting material - fuel: 43.5 % by weight

Calorific value: 7.34 MJ/kg. Example 3:

Mixture composition of total weight of 110,000 kg:

28,000 kg of anaerobically stabilized sludge la5 from a wastewater treatment plant

6,000 kg of cow's manure lb_3

27,000 kg of dendromass 2al - tree leaves

21,000 kg of straw pulp3a2 - fine pulp of rape straw

26,000 kg_of dendromass 2al - wood chips

2,000 kg of rubber products 3c2 - crushed tires

Initial humidity of the mixture: 66.1 % by weight

Process of chemical and biological self-heating took 18 days.

Humidity before combustion of the resulting material - fuel: 54.9 % by weight

Calorific value: 6.78 MJ/kg.

Example 4:

Mixture composition of total weight of 102,000 kg:

20,000 kg of sludge from pulp and paper production lbl 15,000 kg of culture medium of biotechnological production lc5 - deactivated, from pharmaceutical production

12,000 kg of sludge from other productionlM - from industrial wastewater treatment plant for pharmaceutical production

42,000 kg_of dendromass 2al - wood chips

3,000 kg of mowed grass 3a5

4,000 kg of beverage and food packaging 2b_4 - crushed packages of TetraPack-type

6,000 kg of crushed cardboard 2b2

Initial humidity of the mixture: 61.8% by weight

Process of chemical and biological self-heating took 21 days.

Humidity before combustion of the resulting material - fuel: 45.5 % by weight

Calorific value: 7.24 MJ/kg.

Example 5:

Mixture composition of total weight of 106,000 kg:

57,000 kg of anaerobically stabilized sludge la5 from a wastewater treatment plant

2,000 kg of tanning production wastes 3c3 - membrane, subcutaneous fat and hairs from bovine skin processing 19,000 kg of dendromass 2al - tree bark

10,000 kg of scrap paper 2bl and crushed cardboard 2b_2 - unsorted crushed mixture

2,000 kg ofhaylage lcl

8,000 kg of food surpluses lc8 - solid waste from the production of pastries and breadstuffs in the form of fragments of products not meeting the qualitative parameters and samples taken during production

6,000 kg of dendromass 2al - biodegradable waste from a fruit orchard in the form of tree branches, leaves, and cuttings

2,000 kg of mowed grass 3a5 and fruits lc2 - from a fruit orchard

Initial humidity of the mixture: 67.2% by weight

Process of chemical and biological self-heating took 42 days.

Humidity before combustion of the resulting material - fuel: 39.4 % by weight

Calorific value: 8.58 MJ/kg.

Industrial applicability

The composition of the waste material mixture according to the technical solution for the production of direct combustion fuel and the method of production of this fuel are intended for the industrial disposal of bio-waste, as well as the production of fuel for direct combustion or further treatment.