GB2524179A

GB2524179A - System and method for modular batch production of bio-methane from wet municipal solid waste (MSW)

Info

Publication number: GB2524179A
Application number: GB1505662.5A
Authority: GB
Inventors: Mohd Ejaz Sayani
Original assignee: GREEN CONSERVATION RESOURCES Ltd
Current assignee: GREEN CONSERVATION RESOURCES Ltd
Priority date: 2015-04-01
Filing date: 2015-04-01
Publication date: 2015-09-16
Also published as: GB201505662D0; GB2538115A; GB201516339D0; GB2538115B

Abstract

A system for production of bio-methane from wet municipal solid waste (MSW) comprises (i) a segregator subsystem 100 for separating MSW into dry fraction, wet fraction and inert fraction, (ii) a modular digestion subs-system 300 for receiving the wet fraction and converting the wet fraction to bio-methane under anaerobic conditions and and (iii) an automatic purification subsystem 400 for purification of the bio-methane. The segregator subsystem comprises a fractionaliser and an air density separator. The modular digestion subs-system comprises a plurality of digesters, a gas collection unit and an automatic sealing unit wherein the digesters 220 are held in a tank 250 and the space between is filled with water which acts as a jacket. The purification subsystem comprises a housing configured with a balloon, sensors and a purifier. A method for the production of bio-methane from MSW waste comprises layering wet MSW with mixtures comprising mother culture, water and alkali flakes in a sealed anaerobic digester.

Description

System and Method for Modular Batch Production of Bio-methane from Wet Municipal Solid Waste (MSW)

Field of the invention

The present invention relates to a system and method for modular production of bio-methane from Municipal Solid Waste (MSW). More particularly, the invention relates to a system and method for batch production of bio-methane from wet Municipal Solid Waste (MSW) with a modular set up, which can be efficient even at places having low/sub-zero atmospheric temperature.

Background of the invention

Million tons of solid waste is produced annually from municipal, industrial, and agricultural sources. The indiscriminate decomposition of these organic wastes results in large-scale contamination of land, water, and air. Municipal solid wastes (MSW), particularly including domestic household wastes, wastes from restaurants and food processing facilities, and wastes from office buildings comprise a very large component of organic material that can be further processed to energy, fuels and other useful products. At present only a small fraction of available MSW is recycled, the great majority being dumped into landfills. Important concern with the landfill method is waste of land and huge nuisance adding pollution faced with neighbouring locations.

The huge time lapse of 4-5 years is observed for the production of methane is also matter of concern.

Considerable interest has arisen in development of efficient and environmentally friendly methods of processing solid wastes, to maximize recovery of their inherent energy potential and, also, recovery of recyclable materials. One significant challenge in "waste to energy" processing has been the heterogeneous nature of MSW. Solid wastes typically comprise a considerable component of organic, degradable material intermingled with plastics, glass, metals and other non-degradable materials. Unsorted wastes can be directly used in incineration, as is widely practiced in countries such as Denmark and Sweden, which rely on district heating systems (Strehlik 2009). However, incineration methods are associated with negative environmental consequences and do not accomplish effective recycling of raw materials. Clean and efficient use of the degradable component of MSW combined with recycling typically requires some method of sorting to separate degradable from non-degradable material.

Major drawback observed with MSW treatment is that MSW does not dissolve in water to form slurry. Numerous systems have been disclosed in the prior art for making slurry of the MSW for the production of biogas from various sources like cattle dung or domestic vegetable waste. Most of the prior art references disclose continuous system of bio-methanation which is a general operational technique. In continuous process, the slurry is fed into the digester through pumps and the excess slurry which has been in the digester is discharged by pump. An important drawback of the continuous process is that opening the lid of the digester is avoided to make the process continuous.

Another important drawback of the continuous process is that it fails to treat solid waste as the slurry cannot be formed at all because of the nature of the solid raw materials.

Further, presently available biogas production set ups are not intensively equipped with efficient segregation of MSW and efficient anaerobic digestion.

Accordingly, there is a need to provide a system and method for a batch production of bio-methane using wet fraction organic MSW, which overcomes drawbacks of the prior art.

Objects of the invention Some of the objects of the system and the method of the present invention, which at least one embodiment herein satisfies, are as follows: It is an object of the system and the method of the present invention to ameliorate one or more problems of the prior art or to at least provide a useful alternative.

An object of the present invention is to provide technically-commercially feasible method and system for effective utilization of wet organic MSW, in-built with a capability to efficiently segregate MSW.

Another object of the present invention is to produce high yield of 91-93% pure bio-methane using less space.

Yet another object of the present invention is to provide 100% eco-friendly system for disposal of Municipal Solid Waste.

Summary of the invention

A system (500) and method for a batch production of bio-methane using wet fraction organic Municipal Solid Waste, the system characterized in that the system (500) comprises: a segregator sub-system (100), comprising (i) a fractionaliser; and (ii) an air density separator, the segregator sub-system (100) adaptably separate of MSW in a dry fraction, a wet fraction and an inert fraction; a modular digestion sub-system (300) receiving feed from the segregator sub-system (100), the modular digestion sub-system (300) having an automatic sealing unit (150), a plurality of digesters and a collection unit (290), wherein the automatic sealing unit (150) is having an overhead tank (120) coupled with a ball valve (114), an overflow pipe (122), a collection tank (124) and a pump (126), the overhead tank (120) is adaptably configured in-line at one end of the plurality of digesters through the ball valve (114) and another end of the plurality of digesters of the modular digestion sub-system (300) is adaptably connecting to the collection tank (124) through the overflow pipe (122), each modular digester (250) of the plurality of digesters is configured with an inner tank (220) and a flexible lid (230) adaptably facilitating anaerobic digestion therein, each adjacently placed modular digester (250) of the plurality of digester being adaptably configured by removing adjoining wall there-between forming the continuous uniform layer of water jacket therein, the collection unit (290) is adaptably coupled with the flexible lid (230) collecting evolved biogas from each modular digester (250); an automatic purification sub-system (400) connecting with the collection unit (290) of the modular digestion sub-system (300) facilitate purification of evolved biogas into 91- 93% of bio-methane, wherein the automatic purification sub-system (400) is having a housing configured with a balloon (410) coupled with a plurality of slideable ring (420) and a plurality of sensors and a purifier (450).

Brief Description of Drawings

Figure 1 shows a schematic view of a system for a batch production of bio-methane using wet fraction organic Municipal Solid Waste, comprising a segregation subsystem, a modular digester subsystem, and an automatic purifier subsystem.

Figure 2 shows a cross sectional view of a modular digestion sub-system.

Figure 3 shows a cross sectional view of an automatic sealing unit assembly with a plurality of digesters, in accordance with Figure 2.

Figure 4 shows a cross sectional view of a modular digester along with its components, in accordance with Figure 2.

Figure 4A shows schematic view of another embodiment of the modular digester.

FigureS shows a cross sectional view of an alternate modular digester.

Figure 6 shows a front view of a screw conveying unit of the alternate modular digester, in accordance with Figure 5, having stirring arrangement. Figure 6A shows a prior art stirrer arrangement.

Figure 7 shows a front view of a collection unit, in accordance with Figure 2.

Figure 8 shows a flowchart depicting steps required for batch production of bio-methane using wet organic MSW.

Figures 9A, 9B, 9C, 9D, and 9Ea, 9Eb, 9Ec show a fractionaliser arrangement forming part of the segregation subsystem.

Figures bA, lOB show an arrangement of regulated feeding device for the fractional iser.

Figures hA, biB, hiC, liD show a spreader arrangement for the fractionaliser.

Figures 12A, iZB show a rotating cage mechanism.

Figures i3A, 13B, 13C, i3D, 13E, 13F show an air density separator forming part of the segregation subsystem.

Detailed Description

hO The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The following description with reference to the accompanying drawing is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined bythe claims and their equivalents. It includesvarious specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

The terms and words used in the following description and the claims are not limited to the bibliographical meanings) but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

It is to be understood that the singular forms "a", "an" and "the" include plural referents unless the context clearly indicates otherwise.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

According to the present invention there is provided a system and method for modular batch production of bio-methane from wet Municipal Solid Waste (MSW).

The present invention provides a system for a batch production of bio-methane using wet fraction organic Municipal Solid Waste. The present invention provides technically-commercially feasible method and system for effective utilization of wet organic Municipal Solid Waste. The present invention is 100% eco-friendly system that produces high yield of 91-93% pure bio-methane using less space.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring now to figure 1, a system (500) for a batch production of bio-methane using wet fraction organic Municipal Solid Waste (MSW) is illustrated. The system (500) comprises of a segregator sub-system (100), a modular digestion sub-system (300) and an automatic purification sub-system (400).

The segregator sub-system (100) is used for processing MSW in order to separate out non-plastic portions from plastic portions in different sub-types. The system includes a fractionaliser arrangement and an air density separator arrangement. The segregator sub-system (100) adaptably improves efficiency and quality of separation of MSW in to a dry fraction, a wet fraction and an inert fraction through an air density separation principle.

The fractionaliser arrangement is depicted in Figures YA, YB, YC, YD, and 9Ea, 9Eb and YEc.

Figures 9A and YB illustrate an embodiment of the fractionaliser arrangement. Figures YB and YC represent another embodiment thereof. Figures YEa, YEb, and YEc represent various possibilities of configuration of a rotating cage of the fractionaliser arrangement.

The fractionaliser 9100 includes a first conveyor 9102, a spreader 9104, a rotating cage 9106, a side cover 9108 and a second conveyor 9110.

The first conveyor 9102 facilitates conveying of the heterogeneous material to be segregated to the spreader 9104 from where the heterogeneous material is conveyed to land upon the outer/external side of the rotating cage 9106.

Material falling upon the rotating cage 9106 gets segregated into two parts -one part comprising pieces bigger in size than the perforations/slats of the rotating cage 9106, and the other, comprising pieces smaller in size than the perforations/slats and therefore falling inside and passing through the cage, to land upon the conveyor 9110.

The mass comprising bigger particle size is separated by a small roller 9109 or alternatively by a striping roller 9208, and is rejected. This rejected part is nothing but big, oversize masses comprising dry fraction of the MSW.

In an embodiment the first conveyor 9102 may be equipped with a regulated feeding device as depicted in Figures 1OA and lOB. The device comprises a conveyor 1010 and a levelling screw 1020. The conveyor 1010 receives the lumps "L" of MSW formed during initial handling thereof by the loaders, wheeled backhoe, skid steer, and excavators. The conveyor 10 moves along the direction of arrows illustrated in Figure 1OA to cause the lumps "L' to move towards the levelling screw 1020. The levelling screw 1020 is disposed orthogonally to the direction of travel of the lumps on the conveyor 1010. The leveling screw 1020 rotates in a direction opposite to the direction of travel of the lumps on the conveyor 1010 and as the lumps i' strike the screws of the levelling screw 1020, the levelling screw transfers the material from the peak portion of the lumps to the valley portion, thereby levellingthe lumps and providing uniformly distributed MSW to the conveyor 30, which is equivalent to the first conveyor 9102.

A spreader/spreading arrangement (9104) is depicted in more details in Figures hA, 11B, 11C, and liD.

Referring to Figure hA of the accompanying drawings, a spreading arrangement 100 having a spreader 11102 for spreading granular material is illustrated. The spreader 11102 is provided with a convex surface 11104 on which granular material slides. The granular material to be uniformlyspread over a tray 11106 is transferred to the spreader 11102 via a conveyor 11108. The granular material received on the convex surface 11104 of the spreader 11102 slides over the convex surface 11104 and while sliding) the granular material is spread over the convex surface 11104. The convex surface 11104 is having a higher surface area and the passage defined by the convex surface is a diverging passage that diverges in the direction of the flow of the granular material on the convex surface 11104. More specifically, the convex surface on which granular material slides is a section of a cone) such a configuration of the convex surface 11104 facilitates in uniform spreading of the granular material and as the granular material leaves the convex surface 11104, the granular material is uniformly spread and distributed. The uniformly spread and distributed granular material leaving the convex surface 11104 is received on the tray 11106.

Referring to Figure 11B of the accompanying drawings, a spreading arrangement 200 having a spreader 11202 for spreading granular material is illustrated. The spreader 11202 is provided with a convex surface 11204 on which granular material slides. The granular material to be uniformlyspread over a tray 11206 is transferred to the spreader 11202 via a conveyor 11208. The granular material received on the convex surface 11204 of the spreader 11202 slides over the convex surface 11204 and while sliding) the granular material is spread over the convex surface 11204. The convex surface 11204 is having a higher surface area. More specifically, the convex surface on which granular material slides is a section of a cylinder, such a configuration of the convex surface 11204 facilitates in uniform spreading of the granular material and as the granular material leaves the convex surface 11204, the granular material is uniformly spread and distributed. The uniformly spread and distributed granular material leaving the convex surface 11204 is received on the tray 11206.

Referring to Figure 11C of the accompanying drawings, a spreading arrangement 300 having a spreader 11302 for spreading granular material is illustrated. The spreader 11302 is provided with a surface 11304 on which granular material slides. The granular material to be uniformly spread over a tray 11306 is transferred to the spreader 11302 via a conveyor 11308. The granular material received on the surface 11304 of the spreader 11302 slides over the surface 11304 and while sliding, the granular material is spread over the surface 11304. The surface 11304 is having a higher surface area. More specifically, the surface 11304 on which granular material slides is a section of a 3 dimensional triangle having two flat surfaces joined at an apex, such a configuration of the surface 304 facilitates in uniform spreading of the granular material and as the granular material leaves the surface 11304, the granular material is uniformly spread and distributed. The uniformly spread and distributed granular material leaving the surface 11304 is received on the tray 11306.

Referring to Figure 110 of the accompanying drawings, a spreading arrangement 400 having a spreader 11402 for spreading granular material is illustrated. The spreader 11402 is provided with a surface 11404 on which granular material slides. The granular material to be uniformly spread over a tray 11406 is transferred to the spreader 11402 via a conveyor 11408. The granular material received on the surface 11404 of the spreader 302 slides over the surface 11404 and while sliding, the granular material is spread over the surface 11404. The surface 11404 is having a higher surface area. More specifically, the surface 11404 on which granular material slides is a section of a 3 dimensional polygon having one flat surface and two inclined surfaces at either side of the flat surface, such a configuration of the surface 11404 facilitates in uniform spreading of the granular material and as the granular material leaves the surface 11404, the granular material is uniformly spread and distributed. The uniformly spread and distributed granular material leaving the surface 11404 is received on the tray 11406.

Referring again to Figures 9A, 9B, 9C, 90, and 9Ea, 9Eb, and 9Ec: The heterogeneous material is fed over the first conveyor 9102 manually, automatically or semi-automatically. The first conveyor 9102 provides potential energy to the heterogeneous material for facilitating free flow of heterogeneous material over the rotating cage 9106.

In one embodiment, the first conveyor 9102 is disposed at a height that is in the range of 5 to 10 meters above the rotating cage. However, the present disclosure is not limited to any particular height of the first conveyor 9102 above the rotating cage 106. In one embodiment the first conveyor 9102 is a rubber conveyor. However, the present disclosure is not limited to any particular material used for manufacturing the first conveyor 9102.

The heterogeneous material from the first conveyor 9102 is dropped over the spreader 9104. The spreader 9104 facilitates controlled flow of the heterogeneous material towards the rotating cage 9106. More specifically, the spreader uniformly spreads the heterogeneous material over the rotating drum. The spreader 9104 is having more surface area and sometimes a divergent section, such configuration of the spreader facilitates in uniform spreading of heterogeneous material over the rotating cage 99106.

In one embodiment, the spreader 9104 facilitates flow of heterogeneous material over the outside surface of the rotating cage 9106, as mentioned above. Further, there is provided a predetermined gap between the spreader 9104 and the rotating cage 9106.

The rotating cage 9106 can have different configurations. For example, in accordance with an embodiment of the present disclosure the rotating cage 9306 may have a square cross section as illustrated in Figure 9Ea. In accordance with another embodiment, the rotating cage 9406 may have a polygonal cross section as illustrated in Figure 9Eb. In accordance with still another embodiment, the rotating cage 9506 may have a triangular cross section as illustrated in Figure 9Ec.

In one embodiment, the rotating cage 9106 has a plurality of slats configured on an outside surface of the rotating cage 9106 and over the length thereof. Alternatively, in another embodiment of the present disclosure the rotating cage 9106 has a plurality of slats configured on an inside surface of the rotating cage and over the length thereof.

Further, the perforations/gaps are formed between the slats. The perforations/gaps may be of different geometrical and non-geometrical shapes, such as circular, semi-circular, curved, elliptical, rectangular, square and the like. In one embodiment, there are no perforations formed between the plurality of slats and there is only opening formed between the pluralities of slats. In yet another embodiment, one or more layers of the pluralities of slats are formed one above another. Still further, one layer of the plurality of slats is followed by a wire mesh.

In one embodiment, the diameter of a perforation is in the range of 150mm to 600mm.

In one embodiment, the perforations have width equal to the distance between the two consecutive slats. However, the present disclosure is not limited to any particular dimensions of the perforation. In one embodiment, the rotating cage 9106 is powered by means of a motor by utilizing a central shaft disposed at a central portion of the cylinder 9106, wherein the central shaft is rotating at a speed of about 4 to 24 rpm. In one embodiment, the length of rotating cage 9106 is in the range of 2 to 8 m. The rotating cage 9106 has a diameter more than half of the length of the rotating cage 9106. However, the present disclosure is not limited to any particular dimension of the rotating cage 9106.

The mass received on the conveyor 9110 (first embodiment) or alternatively the conveyor 9212 (another embodiment), which is free of dry fraction of the MSW, is passed through another rotating cage (for further segregation), which is an internal rotating cage, having smaller perforations/slats than the rotating cage 9206, further separating out oversize dry fractions. This mass left comprises wet fraction of the MSW, made up of a mix of smaller stones, organic material, heavy plastic (making refuse derived fuel -"RDF') and light plastic.

Instead of placing in series with the fractionaliser, the internal rotating cage may also be placed as alternative to the fractionaliser.

Figures 12A and 12B provide a detailed depiction of the internally fed rotating cage (i.e., the material to be segregated is fed internally, instead of being received on its outer surface).

As shown, the rotating cage mechanism 100 is externally powered with internal feeding mechanism for feeding the material to be segregated into the rotating cage. Such a configuration of the rotating cage facilitates in effective handling of the material to be segregated, as the material is confined within the rotating cage, thereby preventing the material to be segregated from falling off from the rotating cage without being segregated. Such a configuration of the rotating cage also facilitates in better flow of the material to be segregated during the segregation operation. More specifically, as the material to be segregated is fed inside the rotating cage, the centrifugal action assists the flow of the material through the rotating cage. The internally fed rotating cage mechanism 100 includes a rotating cage 12102 and a chain drive mechanism 12104.

The rotating cage 12102 has a driven end 12106 and a non-driven end 12108. The rotating cage 12102 has a gradient towards the drive end 12106. Heterogeneous particles to be separated are fed towards the non-driven end 12108 of the rotating cage 12102. In one embodiment, the rotating cage 12102 has a plurality of slats configured on an inside surface of the rotating cage 12102 and over the length thereof. Further, perforations! gaps are formed between the slats. The perforations! gaps may be of different geometrical and non-geometrical shapes, such as circular, semi-circular, curved, elliptical, rectangular, square and the like. In one embodiment, there are no perforations formed between the plurality of slats and there is only opening formed between the pluralities of slats. In yet another embodiment, one or more layers of the pluralities of slats are formed one above another. Still further, one layer of the plurality of slats is followed by a wire mesh.

In one embodiment, the perforations have width equal to the distance between the two consecutive slats. However, the present disclosure is not limited to any particular dimensions of the perforation. In one embodiment, the length of rotating cage 12102 is in the range of 2 to Sm. The rotating cage 12102 has a diameter more than half of the length of the rotating cage 12106. However, the present disclosure is not limited to any particular dimension of the rotating cage 12102.

The heterogeneous elements having size less than perforation size falls through the perforations and carried over by a conveyor for further segregation! processing. The heterogeneous elements having size bigger than the distance between the two slats falls outside from the driven end 12106 of the rotating cage 12102 over another conveyor for further segregation.

As the heterogeneous particles to be separated are fed inside the rotating cage 12102, the rotating cage is externally driven by various external drive mechanisms such as the chain drive mechanism 12104. The chain drive mechanism 12104 includes a driven sprocket 12110, a drive sprocket 12112 and a chain 12114. The driven sprocket 12110 is disposed on the rotating cage 12102. Particularly, the driven sprocket 12110 is disposed on a drive end 106 of the rotating cage 12102. The drive sprocket 12112 may be powered by various powering devices such as motor and the like. The chain 114 is adapted to transfer power from the drive sprocket 12112 to the driven sprocket 12110 for facilitating rotation of the rotating cage 12102. In one embodiment, the rotating cage 12102 is rotated at a speed of about 4 to 24rpm.

Referring to Figure 12B, an internally fed rotating cage mechanism 200 is disclosed, in accordance one embodiment. The internally fed rotating cage mechanism 200 includes a rotating cage 12202 and a chain drive mechanism 12204. The rotating cage 12202 has a shape of rectangular prism.

The rotating cage 12202 has a driven end 12206 and a non-driven end 12208. The rotating cage 12202 has a gradient towards the drive end 12206. Heterogeneous particles to be separated are fed towards the non-driven end 12208 of the rotating cage 12202. In one embodiment, the rotating cage 12202 has a plurality of slats configured on an inside surface of the rotating cage 12202 and over the length thereof. Further, perforations! gaps are formed between the slats. The perforations! gaps may be of different geometrical and non-geometrical shapes, such as circular, semi-circular, curved, elliptical, rectangular, square and the like. In one embodiment, there are no perforations formed between the plurality of slats and there is only opening formed between the pluralities of slats. In yet another embodiment, one or more layers of the pluralities of slats are formed one above another. Still further, one layer of the plurality of slats is followed by a wire mesh.

In one embodiment, the perforations have width equal to the distance between the two consecutive slats. However, the present disclosure is not limited to any particular dimensions of the perforation. In one embodiment, the length of rotating cage 12202 is in the range of 2 to Sm. However, the present disclosure is not limited to any particular dimension of the rotating cage 12202.

The heterogeneous elements having size less than perforation size falls through the perforations and carried over by a conveyor for further segregation! processing. The heterogeneous elements having size bigger than the distance between the two slats falls outside from the drive end 12206 of the rotating cage 12202 over another conveyor for further segregation.

As the heterogeneous particles to be separated are fed inside the rotating cage 12202, the rotating cage is externally driven by various external drive mechanisms such as the chain drive mechanism 12204. The chain drive mechanism 12204 includes a driven sprocket 12210, a drive sprocket 12212 and a chain 12214. The driven sprocket 12210 is disposed on the rotating cage 12202. Particularly, the driven sprocket 12210 is disposed on a drive end 12206 of the rotating cage 12202. The drive sprocket 12212 may be powered by various powering devices such as motor and the like. The chain 12214 is adapted to transfer power from the drive sprocket 12212 to the driven sprocket 12210 for facilitating rotation of the rotating cage 12202. In one embodiment, the rotating cage 12202 is rotated at a speed of about 4 to 24 rpm.

In another embodiment, the rotating cages 12102 and 12202 are externally driven by means of a miller gear mechanism. The miller gear mechanism is disposed outside of the rotating cages 12102 and 12202. In one embodiment, the miller gear mechanism is of mild steel. Although, the rotating cages 12102 and 12202 described in the above-mentioned embodiments has a cylindrical and a rectangular prism shape respectively.

The present invention is not limited to any particular shape of the rotating cage. In other embodiments) the rotating cage may have spherical shape, triangular prism shape) pentagonal prism shape) hexagonal prism shape, cube shape and the like.

Referring back to Figures 9A, 9B, 9C, 9D, and 9Ea, 9Eb, 9Ec: If any material particle is stuck between the slats of the rotating cage 9106 in such a way that the material is half inside and half outside, then such a material is stuck between the rotating cage 9106 and the side cover 9108. In such condition, the side cover 9108 acts as a brake and stops the rotation of the rotating cage 9106. Consequently, the stuck material has to be removed manually for continuation of the operation of the rotating cage 9106.

Referring to Figure 9A, the fractionalizer 100 further includes a small roller 9109 that is disposed near the exterior surface of the rotating cage 9106. More specifically, the center of the smaller roller 9109 is disposed operatively below the center of the cage 9106 and both the small roller 9109 and the cage 9106 rotate in counter-clock wise direction, with such a configuration of the small roller 9109 and the cage 9106, the smaller roller 9109 receives heterogeneous material from the rotating cage 106 and throws the heterogeneous material away from the exterior surface of the rotating cage 9106 thereby facilitating in directing the heterogeneous material towards a predetermined area. In accordance with an embodiment, the cage 9106 is rotating at a speed of 8-10 rpm whereas the smaller roller 109 is rotating at a speed of 60-80 rpm.

Referring to Figures 9C and 9D, a fractionaliser 200 is disclosed, in accordance one embodiment. The fractionalizer 200 includes a first conveyor 9202, a spreader 9204, a rotating cage 9206, a striping roller 9208, a side cover 9210 and a second conveyor 9212.

The first conveyor 9202 facilitates conveying of the heterogeneous material to be segregated to the spreader 9204 from where the heterogeneous material is conveyed to the rotating cage 9206. The heterogeneous material is fed over the first conveyor 9202 manually, automatically or semi-automatically. The first conveyor 9202 provides potential energy to the heterogeneous material for facilitating free flow of heterogeneous material over the rotating cage 9206. In one embodiment, the first conveyor 9202 is disposed at a height that is in the range of 5 to 10 meters above the rotating cage. However, the present disclosure is not limited to any particular height of the first conveyor 9202 above the rotating cage 9206. In one embodiment the first conveyor 9202 is a rubber conveyor. However, the present disclosure is not limited to any particular material used for manufacturing the first conveyor 9202.

The heterogeneous material from the first conveyor 9202 is dropped over the spreader 9204. The spreader 9204 facilitates controlled flow of the heterogeneous material towards the rotating cage 9206. More specifically, the spreader uniformly spreads the heterogeneous material over the rotating drum. The spreader 9204 is having more surface area and sometimes a divergent section, such configuration of the spreader facilitates spreading of heterogeneous material over the rotating cage 9206.

In one embodiment, the rotating cage 9206 has a plurality of slats configured on an outside surface of the rotating cage and over the length thereof. Alternatively, in another embodiment of the present disclosure the rotating cage 9206 has a plurality of slats configured on an inside surface of the rotating cage and over the length thereof.

Further, perforations! gaps are formed between the slats. The perforations! gaps may be of different geometrical and non-geometrical shapes, such as circular, semi-circular, curved, elliptical, rectangular, square and the like. In one embodiment, there are no perforations formed between the plurality of slats and there is only opening formed between the pluralities of slats. In yet another embodiment, one or more layers of the pluralities of slats are formed one above another. Still further, one layer of the plurality of slats is followed by a wire mesh.

In one embodiment, the diameter of a perforation is in the range of 150mm to 600 mm.

In one embodiment, the perforations have width equal to the distance between the two consecutive slats. However, the present disclosure is not limited to any particular dimensions of the perforation. In one embodiment, the rotating cage 9206 is powered by means of a motor by utilizing a central shaft disposed at a central portion of the cylinder 9206, wherein the central shaft is rotating at a speed of about 4 to 24rpm. In one embodiment, the length of rotating cage 9206 is in the range of 2 to 8 m. The rotating cage 9206 has a diameter more than half of the length of the rotating cage 206.

However, the present disclosure is not limited to any particular dimension of the rotating cage 9206.

The material having size less than perforation size falls through the perforations and is carried over by the second conveyor 9212 for further segregation! processing. The materials having size bigger than the distance between the two slats move over the stripping roller 9208 and falls into a conveyor for further segregation. If any material particle is stuck between the slats of the rotating cage 9206 in such a way that the material is half inside and half outside, then such an element is stuck between the rotating cage 9206 and the side cover 9210. In such condition, the side cover 9210 acts as a brake and stops the rotation of the rotating cage 9206. Consequently, the stuck material has to be removed manually for continuation of the operation of the rotating cage 9206.

In one embodiment, the stripping roller 9208 has a length equal the length of the rotating cage 9206. In one embodiment, the stripping roller 9208 has a diameter in the range of 150 mm to 500 mm. Further, in one embodiment, the stripping roller 9208 is adapted to rotate at a speed of 100 to 300 rpm. The stripping roller 9208 rotates at a comparatively higher speed than the rotating cage 9206. The stripping roller 9208 has a plurality of stripping blades 9214 provided on a circumference thereof for facilitating rotation in conjunction with the rotating cage 9206.

Material from the second conveyor (9212) or alternatively 9110 of the fractionaliser, fractionalised by the rotating cage and/or the internal rotating cage, is received by an air density separator arrangement) which separates non-plastic (i.e. organic) portions from the plastic portion. The former are used for anaerobic digestion and biogas production.

The air density separator arrangement is depicted in Figures 13A, 13B, 13C, 13D and 13E.

According to one embodiment of the present invention as shown in Figure 13A, the system comprises feeding conveyor (132) having an evener roller (133) for evening/levelling the MSW (131) received from the second conveyor (9212); a feeding hopper (135) comprised of an eccentric spreader plate (134), eccentric bearing (1314) and a fan (136); an inclined conveyor (138) carrying away and removing as a continuous flow) a part separated from the MSW; an RDF (Refuse Derived Fuel) carrying conveyor (1310) having a cover (139); a conveyor at right angles (1311) to the RDF carrying conveyor, and a light plastic collection bin (1312).

Segregated MSW (1) received from the second conveyor (9110/9212) is continuously fed at a fix flow rate with a feeding conveyor (1316). The feeding conveyor has an evener roller (132) which ensures that the MSW (1) is levelled to a particular height before passing it on for further processing) thereby maintaining a controlled feeding of MSW.

Construction of the evener is depicted in Figures 13C and 13D. As shown, the evener has ribs on its outer surface, spirally running along its length. The evener roller (132) rotates in a direction opposite to that of the feeding conveyor (1316). When the MSW heap reaches the ribs after travelling along the feeding conveyor) the heap is flattened due to the ribs, and a uniform height of MSW is obtained, which is moved forward.

The evened MSW is then fed into a feeding hopper (135) having an eccentric spreader plate (134) and an eccentric bearing (1314) for vibrating the eccentric spreader plate.

Figures 13E and 13F depict construction of the eccentric spreader plate. The eccentric spreader plate has corrugations (1315) over its surface, the width thereof increasing towards its lower end. Due to the vibrations of the eccentric spreading plate the fed MSW is also vibrated and thereby spread into multiple streams corresponding to the corrugations, thereby improving efficiency and quality of separation of MSW through air density separation.

The spread MSW is then subjected to air blow from a fan (136) which is combination of axial and radial fan. Due to the blow lighter plastic material flies and lands on the RDF carrying conveyor (1310). This conveyor (1310) is erected at a sufficient distance from the feeding hopper (135) (around 500 mm away in a preferred embodiment) from the spreader plate (132) so all material that falls on the RDF carrying conveyor is by the force of air and whatever is heavy falls on the first conveyor (138) placed at some distance below the feeding hopper (135) and goes down as heavy rejects.

The material falling on the first conveyor 138 is the wet fraction of the MSW, used for anaerobic digestion for bio-methane production.

The RDF carrying conveyor has an upward gradient, which causes stones and other heavy particles to roll down the conveyor 1310, which are collected on the bottom conveyor 137, and taken away as rejects.

From the lighter material that falls on the RDF carrying conveyor still more light plastic is further segregated. This is done by maintaining the length of the RDF carrying conveyor around 10 feet and providing a cover (139) over the length. The cover (139) ensures that there is no escape of air and thus air blow does not wane out, and hence the still more light plastic pieces do not drop on the RDF conveyor; but keep flying in air.

Arrangement of the cover (139) over the RDF carrying conveyor (1310) is depicted in Figure 13B.

Due to the blow of the air the still more light plastic pieces keep flying, as explained above; and the not-so-light pieces continue to rest on and travel along the RDF-carrying conveyor. There is another conveyor (1311) placed at right angles to the RDF carrying conveyor.

The not-so-light pieces are dry matter (i.e. RDF) are taken away by the conveyor at right angles (1311). The RDF is useful as alternate fuel, e.g. as replacement of coal in boiler.

The still more light plastic pieces, however, do not fall on the conveyor at right angles (1311); instead) they keep flying along and even beyond the passage of the RDF carrying conveyor under the cover (139) and beyond the conveyor at right angles (1311), and are finally collected in a light plastic collection bin (1312).

The fan 136 is a combination of radial and axial fan (not a centrifugal fan). The fan has a particular design to obtain air flow at a very low pressure compared to that obtained by centrifugal fans. The air outlet of the fan 136 is wide extending over a breadth, unlike in case of centrifugal fans, wherein the same is like a hose, giving a jet of very high pressure air but covering far lesser area.

In a preferred embodiment the size of the feeding hopper is 36" X 36" having an rpm of 400 to 800 of eccentric movements for the spreader activity; the size of fan is 42" of 15 HP having rpm of around 700 to 1000; and the rpm of the various conveyors described above is around 45 to 100.

Referring back to the batch production system 500 and the Figures 1, 2, 3,4, 4A, 5, 6, 6A, 7, and 8: In a preferred embodiment, the raw material includes municipal solid waste, kitchen waste, food waste, paper, leaves, fruit skin and seeds, wood pieces, bagasse, animal excreta such as cow dung, horse dung, pig dung, chicken litter, thermocol, cardboards, cartons, thick wood, cloth, coconut, plastic metal, rubber, glass, sand stones and the like.

Referring to figures 2-4, the modular digestion sub-system (300) is illustrated. The modular digestion sub-system (300) in an embodiment of present invention includes an automatic sealing unit (150), a plurality of digesters and a collection unit (290). The automatic sealing unit (150) of the present invention as shown in figure 3 includes an overhead tank (120), an overflow pipe (122), a collection tank (124) and a pump (126).

The automatic sealing unit (150) maintains the constant circulation of the water around the plurality of digesters. The overhead tank (120) includes an inlet (not numbered) and an outlet (not numbered). The outlet of the overhead tank (120) is adaptably coupled with a ball valve (114) positioned above height of the digester. The outlet of the overhead tank (120) is configured in-line at one end of the plurality of digesters of the modular digestion sub-system (300) through the ball valve (114).The ball valve (114) is preferably position 500mm above the modular digestion sub-system (300).

The overflow pipe (122) is connecting another end of the plurality of digesters of the modular digestion sub-system (300) to the collection tank (124). The overflow pipe (122) is preferably position 300mm above the modular digestion sub-system (300). The collection tank (124) is specially designed tank which has a sensor (124a). The sensor (124a) senses the complete filing of the collection tank (124) and activates the pump (126). The pump (126) helps in re-circulation water from the collection tank (124) to the overhead tank (120).

In an embodiment of present invention, each modular digester (250) of the plurality of digester is a rectangular open tank. Each modular digester (250) includes an inner tank (220) and a flexible lid (230). Each modular digester (250) of the plurality of digester is preferably in range of 12 to 20 m length, 8 to 15 m breath and 2000-3000 m in height.

The space between the modular digester (250) and inner tank (220) is allowed to be filled with water jacket. Each adjacently placed modular digester (250) of the plurality of digester are adaptably configured by removing adjoining wall so as to be lined alongside for forming a continuous and uniform layer of water jacket therein.

The inner tank (220) is a smaller dimension tank enclosed in each of the modular digester (250) therein so as to facilitate a continuous and uniform layer of water jacket for providing anaerobic condition. The inner tank (220) is anaerobically covered with the flexible lid (230) adaptably connecting to the collection unit (290).

Figure 4A depicts another embodiment of the modular digester arrangement. As shown, the inner tank extends below the ground level, and is jacketed with a hot material. In a preferred embodiment, the hot jacketing material is sludge remained after an aerobic digestion process. Alternatively, hot water may also be used. The jacket is along the sides of the inner tank from ground level upwards, covering its height.

There are two balloons. A first balloon acts as lid, and is always deflated. This balloon serves to maintain anaerobic condition. A second balloon extends over the first balloon, and is inflated with hot air, the hot air thus forming a jacket over the first balloon. The hot air jacket serves as insulation, preventing the low/sub-zero atmospheric temperature conditions from affecting the anaerobic digestion and biogas generation process. In a preferred embodiment the digester extends around 1.5 metres below the ground level, and has a height of around 3 metres.

Referring to figures 5-6, an alternate embodiment of an inner tank (220a) is illustrated.

The inner tank (220a) of each the modular digester (250) is partitioned in at least three compartments (222a) and has at least two screw conveying unit. Each screw conveying unit (230a) of the at least screw conveying unit comprises a screw agitator (224a), an 0-seal ring (226a) and a motor (228a). Each screw conveying unit (230a) facilitates agitation while maintaining anaerobic condition through the inner tank (220a).

Figure 6 depicts a stirring arrangement for stirring the MSW mass in the modular digester tank. Figure GA provides reference of a stirrer arrangement according to prior art.

The collection unit (290) in the present embodiment as shown in figure 2 includes a collecting tube (292), a non-return valve (294), a flow meter (296) and a central duct (298). The central duct (298) is designed in increasing diameter to maintain atmospheric pressure condition in each modular digester (250) of the plurality of digester as shown in the figure 2. The central duct (298) is of increasing diameter being narrower at the initial end of plurality of digesters increasing broader towards of final end of plurality of digesters. In an embodiment of the present invention, the central duct (298) is in increasing diameter of 4 m, 8 m and 12 m. The collection unit (290) is connected to the automatic purification sub-system (400).

Referring now to figure 7, the automatic purification sub-system (400) in the present embodiment is shown. The automatic purification sub-system (400) includes a housing (not numbered), a balloon (410), a plurality of slideable ring (420), a plurality of sensors and a purifier (450). The balloon (410) is an inflatable elastic member which performs collection of the evolved biogas from the plurality of digesters. The balloon (410) is secured with the plurality of slideable ring (420) in a manner such that upon collection of biogas from the central duct (298), the balloon (410) rises upwardly in the housing wherein the plurality of slideable rings (420) slides along the side panel of the housing.

Each sensor (430) of the plurality of sensors is positioned so perform controlled operation of collection of biogas in the balloon (410). In an embodiment of the present invention, at least one first sensor in positioned on a first end of the housing in proximity of the central duct (298) and at least one second sensor in positioned on a second end of the housing. Upon evolution of the biogas from the plurality of digesters the central duct (298) passes the biogas in to the balloon (410), at this step the at least one first sensor is activated. Further, the balloon (410) rises upwardly in the housing up to the height of the housing till the at least one second sensor is activated. The at least one second sensor send signal to a pump (not shown) of the purifier (450) to suck the biogas and initiate the process of purification of the collected biogas from the balloon (410) in to bio-methane. The purifier (450) includes a chiller (not shown), a cooler (not shown), a moisture remover (not shown), a desulfurizer (not shown) and an absorber (not shown) through which the biogas is purified to 91-93% of bio-methane.

Referring now to figure 8, there is shown a flowchart of a method (1000) for a batch production of bio-methane using wet fraction organic Municipal Solid Waste (MSW) in an anaerobic modular digester (250), in aspect of the present invention.

The method (1000), at step (1100) includes collecting and segregation of raw materials from the MSW in to dry, wet and inert fraction using the segregator sub-system (100).

In preferred embodiment, the raw material includes municipal solid waste, kitchen waste, food waste, paper, leaves, fruit skin and seeds, wood pieces, bagasse, animal excreta such as cow dung, horse dung, pig dung, chicken litter, thermocol, cardboards, cartons, thickwood, cloth, coconut, plastic metal, rubber, glass, sand stones and the like are separated in to dry, wet and inert fraction.

At step (1150), in accordance with method (1000); the modular digester (250) is filled with a first layer of a mixture A having predefined amount of mother culture, water and alkali flakes. In the present embodiment, the mixture A includes 2500 litres of mother culture, 50000 litres of water and 175 kg of alkali flakes. The alkali flakes in the present embodiment is sodium hydroxide (NaOH) flakes.

The mother culture is prepared from rice bran. For a digester tank of capacity 20000 litres, around 20 kg of rice bran is mixed with around 100 litres of water and pumped into the digester tank. The mixture is left for a week in anaerobic condition, whereupon the mother culture is ready. For next quantum of mother culture, after removal of the first quantum around 10000 litres of water is added to the tank and around 10 kg of rice bran is mixed, and left in anaerobic condition for a week. The process is repeated for meeting next requirement.

At step (1200), the modular digester (250) is added with separated / segregated wet fraction of the MSW from the segregator sub-system (100), which mainly includes of organic raw materials. The modular digester (250) in the present embodiment is charged with 350 Mt of separated wet fraction of the MSW.

At step (1250), the modular digester (250) is added with a second layer of a mixture B having predefined amount of mother culture and alkali flakes. The water is further added till the entire content of the modular digester (250) are submerged. In the present embodiment, the mixture B includes 2500 litres of mother culture and 175 kg of alkali flakes. The alkali flakes in the present embodiment is sodium hydroxide (NaOH) flakes.

At step (1300), anaerobically sealing of the inner tank (220) is done using the flexible lid (230) thereby allowing the automatic sealing unit (150) to maintain the constant circulation of the water over each modular digester (250), in order to maintain anaerobic condition. The modular digester (250) is allowed to undergo anaerobic digestion for a period of 70-120 days. In the preferred embodiment, the modular digester (250) is allowed to undergo anaerobic digestion for a period of 90 days.

At step (1350), the modular digester (250) is added with a third layer of a mixture C having predefined amount of having digested sludge, mother culture and alkali flakes.

In the present embodiment, the mixture C includes 2OMt of digested sludge, 500 litres of mother culture and 175 kg of alkali flakes. The alkali flakes in the present embodiment is sodium hydroxide (NaOH) flakes.

At step (1400), anaerobically sealing of the inner tank (220) is done using the flexible lid (230) thereby allowing the automatic sealing unit (150) to maintain the constant circulation of the water over the modular digester (250) maintain anaerobic condition.

The modular digester (250) is allowed to undergo anaerobic digestion for a period of 70-days. In the preferred embodiment, the modular digester (250) is allowed to undergo anaerobic digestion for a period of 90 days.

At step (1450), post anaerobic digestion, the biogas generated in the modular digester (250) is collected through the collection unit (290) and the solid digested / digested sludge is removed to be used in fresh digester or Window floor. The slurry produced in anaerobic digestion is allowed to remain in the modular digester (250).

At step (1500), the modular digester (250) is re-filled with a first layer of a mixture D having predefined amount of mother culture, water and alkali flakes. In the present embodiment, the mixture D includes 500 liters of mother culture, 20000 liters of water and 175 kg of alkali flakes. The alkali flakes in the present embodiment is sodium hydroxide (NaOH) flakes.

At step (1550), the modular digester (250) is added with separated wet fraction of the MSW from the segregator sub-system (100), which mainly includes of organic raw materials. The modular digester (250) in the present embodiment is charged with 350 Mt of separated wet fraction of the MSW.

At step (1600), the modular digester (250) is layered with a second layer of a mixture E having predefined amount of mother culture and alkali flakes. The water is further added till the entire content of the modular digester (250) are submerged. In the present embodiment, the mixture E includes 500 liters of mother culture and 175 kg of alkali flakes. The alkali flakes in the present embodiment is sodium hydroxide (NaOH) flakes.

At step (1650), anaerobically sealing of the inner tank (220) is done using the flexible lid (230) thereby allowing the automatic sealing unit (150) to maintain the constant circulation of the water over each the modular digester (250) maintain anaerobic condition. The modular digester (250) is allowed to undergo anaerobic digestion for a period of 70-120 days. In the preferred embodiment, the modular digester (250) is allowed to undergo anaerobic digestion for a period of 90 days.

At step (1700) of the method (1000), the biogas generated in the modular digester (250) is further allowed to be passed in to automatic purification sub-system (400) through the collection unit (290) thereby results in generation of 91-93% purified bio-methane.

The purified bio-methane gas comprises of methane, carbon dioxide (C02), gross calorific value (GCV) and hydrogen sulphide (H2S) and Moisture. In an embodiment of the present invention, the purified bio-methane comprises of methane composition is 91-93%, C02 is 45%, GCV and H2S is 8200-8500 kg, and the moisture content is less than ppm after scrubbing.

In present embodiment the mother culture is prepared using rice bran with water thereby the contents are further allowed to undergo anaerobic digestion for 7-15 days.

Tabular experimental results: ____________ 3xV "ru Q 4$'tt\-I _______ 13 I 3E LZ4 __________ $12 _________ ftr% C $3S 5tnrt 1W 11t -.----.,.--..

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:.: ____ ______st MT Ml tiC t.tdt&trsrø .*nu m tkcr --;nztns s ns4 nn* 124.c)b LL __-a --Dl? IX4' L)EL!!.. i i -.

Li$sss:4aLs..

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-. Iv Advantages of the invention: 1. The system (500) and method (1000) facilitates effective utilization of wet organic MSW.

2. The system (500) and method (1000) enables production of high yield of 91-93% pure bio-methane using less space.

3. The system (500) and method (1000) provides 100% eco-friendly system for disposal of Municipal Solid Waste.

Claims

We claim: 1. A system (500) for a batch production of bio-methane using wet fraction organic Municipal Solid Waste, characterized in that the system (500) comprises: a segregator sub-system (100), comprising (iii) a fractionaliser; and (iv) an air density separator, the segregator sub-system (100) adaptably separate of MSW in a dry fraction, a wet fraction and an inert fraction; a modular digestion sub-system (300) receiving feed from the segregator sub-system (100), the modular digestion sub-system (300) having an automatic sealing unit (150), a plurality of digesters and a collection unit (290), wherein the automatic sealing unit (150) is having an overhead tank (120) coupled with a ball valve (114), an overflow pipe (122), a collection tank (124) and a pump (126), the overhead tank (120) is adaptably configured in-line at one end of the plurality of digesters through the ball valve (114) and another end of the plurality of digesters of the modular digestion sub-system (300) is adaptably connecting to the collection tank (124) through the overflow pipe (122), each modular digester (250) of the plurality of digesters is configured with an inner tank (220) and a flexible lid (230) adaptably facilitating anaerobic digestion therein, each adjacently placed modular digester (250) of the plurality of digester being adaptably configured by removing adjoining wall there-between forming the continuous uniform layer of water jacket therein, the collection unit (290) is adaptably coupled with the flexible lid (230) collecting evolved biogas from each modular digester (250); an automatic purification sub-system (400) connecting with the collection unit (290) of the modular digestion sub-system (300) facilitate purification of evolved biogas into 92-93% of bio-methane, wherein the automatic purification sub-system (400) is having a housing configured with a balloon (410) coupled with a plurality of slideable ring (420) and a plurality of sensors and a purifier (450).
2. The system (500) as claimed in claim 1, wherein the collection tank (124) having a sensor (124a) therein facilitates re-circulation of water to the overhead tank (120) from the collection tank (124) in assistance of the pump (126).
3. The system (500) as claimed in claim 1, wherein the ball valve (114) is positioned 500mm above the modular digestion sub-system (300).
4. The system (500) as claimed in claim 1, wherein the overflow pipe (122) is positioned 300 mm above the modular digestion sub-system (300).
5. The system (500) as claimed in claim 1, wherein the inner tank (220a) of each the modular digester (250) is partitioned in at least three compartments (222a) and have at least two screw conveying units.
6. A method (1000) for a batch production of bio-methane using wet fraction organic Municipal Solid Waste (MSW) in a modular digester (250), characterized in that the method (1000) comprising the steps of: collecting and segregating the MSW in to a dry fraction, a wet fraction and an inert fraction using the segregator sub-system (100); layering of a first layer having a mixture A in the modular digester (250), wherein the mixture A have a predefined amount of mother culture, water and alkali flakes; adding segregated wet fraction from the segregator sub-system (100) over the first layer in the modular digester (250); layering of a second layer having a mixture B above the contents of the modular digester (250) and adding water for submerging the contents, wherein the mixture B have a predefined amount of mother culture and alkali flakes; allowing anaerobic digestion of the water submerged contents by anaerobically sealing the inner tank (220) for a period of 70-120 days; layering of a third layer having a mixture C in the modular digester (250), wherein the mixture C have a predefined amount of digested sludge, mother culture, water and alkali flakes; allowing anaerobic digestion of the mixture C added contents by anaerobically sealing the inner tank (220) for a period of 70-120 days; collecting evolved biogas and removing of digested sludge from the modular digester (250) thereby leaving anaerobic slurry therein; refilling of the modular digester (250) with a first layer having a mixture D in the modular digester (250), wherein the mixture D have a predefined amount of mother culture, water and alkali flakes; adding segregated wet fraction from the segregator sub-system (100) over the first layer of mixture Din the modular digester (250); layering of a second layer having a mixture E upon the first layer of mixture D of the modular digester (250) and adding water for submerging the contents, wherein the mixture B have a predefined amount of mother culture and alkali flakes; allowing anaerobic digestion of the water submerged contents by anaerobically sealing the inner tank (220) for a period of 70-120 days; and purifying the evolved biogas from the modular digester (250) by subjecting the biogas in an automatic purification sub-system (400) for producing purified bio-methane.
7. The method (1000) as claimed in claim 1, wherein the mixture A includes 2500 liters of mother culture, 50000 liters of water and 175 kg of alkali flakes.
8. The method (1000) as claimed in claim 1, wherein the mixture B 2500 liters of mother culture and 175 kg of alkali flakes.
9. The method (1000) as claimed in claim 1, wherein the mixture C includes 2OMt of digested sludge, 500 liters of mother culture and 175 kg of alkali flakes.
10. The method (1000) as claimed in claim 1, wherein the mixture D includes 500 liters of mother culture, 20000 liters of water and 175 kg of alkali flakes.
11. The method (1000) as claimed in claim 1, wherein the mixture E includes 500 liters of mother culture and 175 kg of alkali flakes.
12. The system in accordance with Claiml, wherein the fractionaliser further comprises a first conveyor having a regulated feed device, to feed in the MSW uniformly and regularly; a spreader for spreading the uniformly fed MSW; a rotating cage having perforations/slats/wire mesh to receive on its outer surface and further segregate, the spread MSW according to the physical qualities of its granules, an internal rotating cage receiving portion of MSW passed through the rotating cage and further segregating it by passing the same through its perforations/slats/wire mesh) and a second conveyor for collecting and feeding the segregated MSW further to the air density separator; and the air density separator further comprising: a feeding conveyor (2) for moving the MSW; a feeding hopper (5) having a fan (6), being, the hopper receiving the MSW, spreading the received MSW, and subjecting the spread MSW to air blow from the axial fan (6); and a refuse derived fuel (RDF) carrying conveyor (10) placed at a horizontal distance from the feeding hopper (5) and receiving portions of the MSW moved due to air blow from the axial fan (6); characterized in that, the feeding conveyor comprises (i) an evener roller (3) having ribs along its outer surface and moving in a direction opposite to that of the feeding conveyor and evening out the MSW into a layer of uniform thickness and volume; and (ii) an eccentric bearing (14) vibrating the eccentric spreader plate (4); the feeding hopper (5) further comprises (i) an eccentric spreading plate (4) placed at an angle with vertical, the plate having corrugations (15) over its surface, and (ii) an eccentric bearing connected to and vibrating the eccentric spreading plate; the fanG is a combination of axial and radial fan and has an air outlet extending over a breadth and thus covering much broader area than centrifugal fan, and emitting air at pressure lower than centrifugal fan; and the refuse derived fuel (RDF) carrying conveyor (10) has a cover (9) along its length, and is inclined forward, having an upward gradient; wherein first heavy and non-plastic granules are separated from the MSW and carried away along a first conveyor 8, and the MSW is segregated further into (i) RDF moving along the RDF carrying conveyor 10, (ii) heavy rejects rolling down the conveyor 10, and (iii) light plastic flying due to blow of the fan 6 and moving within and under the cover 9 in air; and the separated non-plastic granules, carried along the firs conveyor 8, are nothing but wet fractions of the MSW, and are used for anaerobic digestion.
13. The system according to Claim 12, wherein the corrugations (15) are narrower at an upper end of the eccentric spreading plate and get wider towards a lower end of the eccentric spreading plate.
14. The system according to Claim 12, further comprising a conveyor at right angles to the RDF carrying conveyor (11), for taking away the MSW portion resting on and moving along the RDF carrying conveyor.
15. The system according to Claim 12, further comprising a bin (12) for collecting portion of the MSW mainly plastics as they are the lightest objects moving in air along the passage formed by the RDF carrying conveyor (10) and the cover (9) due to air blow from the axial fan (6).
16. The system according to Claim 12, further comprising a bottom conveyor (7) for collecting parts of the MSW material not falling on the first conveyor (8) but not landing upon the RDF carrying conveyor (10), such parts, being organic dry MSW, to be used for anaerobic digestion.
17. The system according to Claim 12, wherein the horizontal distance between the feeding hopper (5) and the RDF carrying conveyor (10) is around 500 millimetres.
18. The system according to Claim 12, wherein the ROE carrying conveyor (10) is around feet long.
19. The system according to Claim 12, wherein size of the feeding hopper (5) is 36" X 36", rpm of vibrations of the eccentric bearing (14) is 400 to 800; the size and power of the axial fan (6) are 42" and 15 HP and the rpm thereof is around 700 to 1000; and the rpm of the various conveyors described above is around 45 to 100.
20. The system according to Claim 12, wherein the rotating cage further comprises a drive end, a driven end, and slats and/or perforations and/or wire mesh following the slats.
21. The system according to Claim 12, wherein the spreader has a convex surface (104) for receiving granular material to be spread, the convex surface having a higher surface area, and the passage defined thereby being a diverging passage, wherein the granular material is received at the tip of the convex surface, and is uniformly spread along the diverging passage of the convex surface as it slides along the convex surface towards its bottom.
22. The system in accordance with Claim 1, wherein the anaerobic digester subsystem comprises one or more partitions and a stirring arrangement, comprising: a lid comprising channels (223a) in its frame) the lid covering an inner tank (220a) of an anaerobic digester and partitioning the inner tank into multiple compartments (222a) by providing a slab on top with water jacket whereby the tank is separated at the top but below it is one tank; at least one screw conveyor unit (230a) fitted in the channel (223a) on the slab, thus ensuring multiple screw conveyor units for the inner tank; at least one 0-seal ring (226a) contained in the lid, sealing the inner tank from the water jacket and thereby making the tank anaerobic; and at least one taper-shaped screw agitator (224a) attached to the screw conveyor unit, in order to penetrate through and stir solid/dry MSW, wherein processing without downtime is ensured due to removability of a single screw conveyor unit in a compartment (222a) while operation continues in the remaining compartments (222a).
23. The system in accordance with Claim 1, wherein the modular digester subsystem comprises: a digester tank having the inner tank extending below the ground level and has jacket around and adjacent to the inner tank formed by sludge from material digested in an aerobic digestion process, covering the height of the modular digester tank; an inner balloon forming lid and maintaining anaerobic conditions; and an outer balloon inflated with hot air, the hot air forming insulation and preventing the low/sub-zero atmospheric temperature from affecting the anaerobic digestion.
24. The method of Claim 6 wherein the mother culture is prepared from rice bran, such that for a digester tank of capacity 20000 litres, around 20kg of rice bran is mixed with around 100 litres of water and pumped into the digester tank; the mixture is left for a week in anaerobic condition, whereupon the mother culture is ready; for next quantum of mother culture, after removal of the first quantum around 10000 litres of water is added to the tank and around 10kg of rice bran is mixed, and left in anaerobic condition for a week; and the process is repeated for meeting next requirement.
25. The system in accordance with Claim 12 wherein the air outlet of the fan 6 is around inches (breadth/horizontal dimension) by 4 inches (height/vertical dimension).