COMPLETE SPECIFICATIONS Detailed description of figures
Fig. 1shows a sectional view of a complete biogas plant resting on ground. It comprises of two main parts: 1) Stationary shell and 2) free-floating gasholder dome. The components visible from the outside include the digester stationary shell resting on the ground, the floating gasholder dome on top, and a solar water heater on the side. Attached to the stationary shell are the combined feed and slurry manifold [102], the gas manifold [107], the pipes for organic feed, the discharged slurry and gas retrieval and a funnel for introducing the organic waste and a container to collect the discharged slurry.
The water jacket [105] is filled with water upon which the gasholder floats completely freely. The water jacket [105] is connected with inlet and outlet pipes to connect with an external heat source.
Fig 2shows the gasholder dome and the internal mechanical structure including the centre stirrer [203], supporting funnel [202], compartments [201] for balancing weights and stabilization slots [204].
The gasholder dome freely floats on the water jacket [105] shown in Fig 1 and it can be rotated 360 degrees without any obstruction. When the gasholder dome is rotated, it also turns the agitator [203] along with, which agitates the slurry and breaks the scum that forms on the top of the slurry inside the digester.
Fig 3shows a number of units placed in series, connected via piping going into and coming out of the manifold [102, 301].Each unit is provided with an eccentrically placed internal partition [302], thus dividing the digester space into two compartments.
Fig. 4 shows a conceptual view of the fully assembled system.
Detailed explanation of the claims
1. Prior art designs either are based on a central guide or external framework to support the gasholder which floats on the slurry. What is claimed in this invention is a gasholderdome [404]that floats 100% freely either on slurry or on a water jacket [105] without any internal support such as central guide or external support such as metal framework. Several other innovations allow making the gasholder dome completely free-floating:

• Biogas collected in the gasholder dome is conveyed through an internal pipe, of claim 8 to the gas manifold [107] of claim 9.
• Placement of weightsin special compartments [201] in the gasholder dome, of claim 15 and in the central agitator [203] of claim 13.

2. The stationary shell [401 ]of the biogas plant comprises of two components: 1) A cylindrical outer shell which is open on one end at the top, and 2) a cylindrical Inner shell which is open on both ends. The cylindrical outer shell tapers to a narrower diameter towards the bottom. The inner shell is of slightly smaller dimension and slides into the outer shell and interlocks [101] into the outer shall, forming an annular space for a water jacket [105]. Two shells (inner shell and outer shell) are precision designed and can be manufactured by a number of different techniques, such as, but not limited to Rotational moulding, injection moulding, Fibre Re-enforced Plastic and Glass Re-enforced Plastic. The two shells can be either joined together simply by press-fit or application of any adhesive material. What is claimed in this invention is the novel design that allows creating the water jacket in the annular space between two different components.
3. The water jacket [105]of claim (2) is filled with water and provided by appropriate piping and valves to allow connecting and controlling heat input from external heat source such as, but not limited to,solar heater, so that the biological conversion is carried out at the optimum temperature for maximum gas production.Valves are also provided to control the quantity of water in the water jacket for optimum heat transfer.
4. The biogas plant has been provided with an eccentrically placed internal partition [302] designed to segregate two different clusters of bacteria colonies - acid forming and Methane forming - so that each cluster type can have the necessary residence time to consume the organic waste or their intermediate products to allow higher production of methane. The partition allows the bacteria clusters to exist in different habitats with different pH value and nutritional compositions. This innovation claims any eccentrically placed partition.
5. The internal partition [302] of claim 4 is provided with a notch that is placed on the opposite end from the manifold [102], [402] of claim 6. This arrangement maximizes the travel path and travel time for organic waste within the digester to go from the inlet to the outlet. This innovation claims any notch or gate in the partition that maximizes travel time within the digester.
6. The biogas plant is provided with a single combined slurry manifold [102], [402] which is provided with two internal chambers - one for incoming organic feed and the other for discharge of the digested slurry. This

innovation claims a single combined manifold for inlet and outlet that can be manufactured by a number of different techniques, such as, but not limited to Rotational moulding, injection moulding, Fibre Re-enforced Plastic and Glass Re-enforced Plastic.
7. The single combined slurry manifold [102],[402] of claim 6is designed with two inlet and two outlet nozzles, allowing a) emergency discharge of the slurry, and b) placement of several units in series [301] to handle larger quantity of organic waste. This invention eliminates complex and longer piping to connect multiple units in series or parallel thus reducing likelihood of choking up of the lines.This innovation claims a single manifold that provides multiple inlet and outlet nozzles that enable connecting multiple units.
8. The biogas plantis provided with an internalpipeconnecting the open space inside the free-floating gasholder dome [404]of claim 1 and the gas manifold [107],[403]. This pipe allowsconveying biogas collected in the gasholder dome through the gas manifold[107], [403], isolation valve [106]and the exit gas pipe [103]. Prior art designs require extracting gas from the gasholder dome. This innovation allows making the gasholder dome [404] to rotate completely untethered.
9. The biogas generated is saturated with moisture which condenses into water and chokes up the gas pipe if it is not periodically drained. The gasmanifold [107],[403] is provided with an integral moisture trap to remove water condensate [104] that is collected within the gas manifold. The trap consists of an internal pipe, one end of which stays submerged in the water within the gas manifold [107],[403] and the other end discharges water to the outside. The height of this pipe is designed so that excess condensate water is automatically emptied by the pressureof the biogas within gasholder dome [404]. This design automatically empties the condensate water without requiring any manual action. What is claimed in this invention is a self-emptying condensate chamber as an integral part of the biogas plant.
10. Biogas generated from organic waste is accompanied by carbon and sulphur particulates which, over time, form a crust on the cooking burners and impart smell of rotten eggs. This necessitates periodic cleaning of the burner. The gas manifold [107],[403] of claim 9is designed to maintain a water column through which the biogas is passed. The manifold is filled with packing material to scrub the particulates. Scrubbed sulphur and carbon particulates are removed along with the condensate water that is removed from the self-emptying condensate chamber of claim 9. This innovation claims automated scrubbing of carbon and sulphur particulates from the biogas before the gas is distributed for use.

11. Free-floating gasholder dome [404] of claim 1 is provided with stabilization slots [204] near the bottom edge which release excess gas to maintain stability of the system. When there is excess biogas, the gasholder lifts up over the water level until the height of the slots [204] exceeds that of the water level, which allows releasing the excess biogas. Prior art designs require tilting of the gasholder dome on one side, thus destabilizing the gasholder dome. This innovation claims provision of the stabilization slots.
12. Free-floating gasholder dome [404] of claim 1is provided with a central agitator [203]comprising of a number of fins. The agitator [203] stays submerged in the slurry. When the free-floating gasholder dome [404]is rotated manually, the agitator [203] also rotates breaking the scum layer and providing fresh nutrient to the bacterial colonies thus increasing conversion of organic material into biogas. This innovation claims specifically designed and centrally connected agitator that thoroughly mixes the slurry. Prior art designs provide internal framework within the biogas holder that only provide partial mixing.
13. The fins of the central agitator [203] of claim 12 are provided with slots to reduce torque when the agitator is rotated in the slurry. This innovation claims slots in the fins of the agitator that allow reduced torque even while providing adequate mixing and scum breaking action.
14. The gasholder dome [404] has been provided with compartments for weights or sand-bags [201]along the circumferenceat the bottom edge of the gasholder dome. Weights at the lowest point on the gasholder dome provide stability and allow dispensing of any support framework. The weights impart pressure to the biogas which is required to convey the gas through the gas pipeline [103]. Necessary pressure can be obtained by adjusting the weights in the compartments. This innovation claims specifically designed compartments for weight on the gas holder dome.
15. The central agitator [203] of claim 12 is provided with a cavity that can be filled with sand or other heavy weights. Placement of weight at the lowest portion of the gasholder dome lowers the centre of gravity of the gasholder dome, therebystabilizing it.Prior art designs do not offer strategic placement of weight to stabilize the free floating biogas dome.

CLIAMS:1. A pre-fabricated portable household biogas plant which is provided with a gasholder dome that is completely free of any external or internal support, anchor or guide and that can be rotated 360 degrees by a gentle push.

2. The gasholder dome in the biogas plant of claim (1) floats on water that can be stored in an annular space that is created when two precision fabricated shells are pressed together to form the outer shell of the biogas digester.

3. The quantity and temperature of the water contained in the annular space of claim (2) can be controlled for maximum conversion of organic waste into biogas.

4. The plant of claim (1) is provided with an internal partition to segregate bacterial colonies that increases conversion of organic waste into biogas and reduces likelihood of digester content becoming acidic.

5. The partition of claim (4) is provided with a notch to increase the travel path and travel time for organic waste to go from the inlet to the outlet which increases conversion of organic waste into biogas.

6. The digester of claim (1) is provided with a single combined manifoldfor incoming organic feed and outgoing digested slurry to reduce cost of manufacturing and enable self-assembly by end-user.

7. The single manifold of claim (6) is designed with two inlet and two outlet nozzles allowing flexibility of emergency discharge and scalability by connecting multiple units in series.

8. The digesterof claim (1) is provided with a pipeline inside the digester to allow extracting biogas collected in the gasholder dome without touching the gasholder dome thus enabling it to rotate completely untethered.

9. The internal pipeline of claim (8) conveys the biogas into a gas-manifold provided with a self-emptying trap which automatically removes water condensate.

10. The gas-manifold of claim (9) is designed to automatically scrub out sulphur and carbon particulates before conveying biogas for end-use.

11. The gasholder dome in the plant of claim (1) is provided with stabilization slots towards the bottom edge through which excess biogas releases to maintain stability of the system

12. The gasholder dome in the plant of claim (1) is provided with a central agitator with fins which when the gasholder dome is rotated also rotates 360 degrees and agitates the slurry thus providing fresh nutrient to the bacterial colonies and breaking the scum layer.

13. The central agitator of claim (12) is provided with a cavity that can be filled with sand or other heavy weights that stabilizes the gasholder dome and provides pressurized biogas for end-use.

14. The fins in the central agitator of claim (12) are provided with a number of slots to reduce torque when the agitator is rotated in the slurry.

15. The gasholder dome in the digester of claim (1) is provided with compartmentsat the circumference of the gasholder dome which can be filled with sand or other heavy weights that stabilizes the gasholder dome and provides pressurized biogas for end-use.
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