WO2019111202A1

WO2019111202A1 - Digester vessel for treating sewage

Info

Publication number: WO2019111202A1
Application number: PCT/IB2018/059715
Authority: WO
Inventors: Asim C. BOSE
Original assignee: Alutec Environmental Systems International Inc.
Priority date: 2017-12-06
Filing date: 2018-12-06
Publication date: 2019-06-13

Abstract

A scalable digester vessel for digesting and decomposing sewage or sludge and producing hydrogen and carbon dioxide gas to be used for commercial purposes. It provides the unique arrangement of electrodes for efficient processing of waste sludge and to minimize methanogenesis thereby expediting the process with digestion time reduced to less than 10 days. A typical direct current capable of generating a controlled electrical field is passed with the voltage approximately 2-3 volts. The hydrogen produced through the vessel does not require the use of fossil fuels, sunlight and used to provide useful energy to the communities having relatively undeveloped electricity distribution.

Description

DIGESTER VESSEL FOR TREATING SEWAGE

FIELD OF THE INVENTION

The present invention relates to an apparatus for digesting and decomposing waste and collection of Hydrogen and Carbon Dioxide gas. More particularly, the present invention relates to a scalable design of a digester vessel for the treatment of waste and production of volume of gases for commercial application.

BACKGROUND OF THE INVENTION The ever increasing population of world is expected to accommodate approximately 2.1 billion more people by 2030. The increasing population is further exerting pressure in various sectors such as food requirements and production, energy requirements and production and pollution control. An average of 1.42 kg of municipal solid waste is expected to be produced per day by each person which is more than double the current average of 0.64 kg per day. However, only a small percentage of this waste is being treated in the developing World.

Sewage is a mixture of domestic and industrial wastes and contains more than 99% water with some ions, suspended solids and harmful bacteria that must be removed before the water is released into any water body or finally disposed. The sewage water is treated for removal of large solids and further treated for removal of scum and solids settling down in the bottom. Furthermore, the sludge is treated in sludge digesters wherein chemical decomposition of sludge is catalysed by microorganisms. The most common digestion techniques include aerobic digestion and anaerobic digestion. Here, anaerobic digestion is a combination of various processes by which microorganisms break down biodegradable material in the absence of oxygen.

In anaerobic digestion, bacterial hydrolysis of the sludge takes place initially wherein insoluble organic polymers breakdown to soluble derivatives to turn accessible for other bacteria. Now, the acidogenic bacteria convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. These bacteria convert the resulting

l organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide. Finally, methanogens convert these products to methane and carbon dioxide.

Anaerobically decomposed organic materials if treated by passage of a relatively small and/or intermittent electric current; production of hydrogen is enhanced while formation of methane is suppressed. Such treatment permits production of hydrogen from typical waste materials such as are found in municipal waste sites and sewage treatment plants, in amounts such that the chemically stored potential energy of the hydrogen produced exceeds the energy required to generate the electric current, whilst simultaneously reducing the mass of the waste material and/or reducing the time required to treat or dispose of such material.

In anaerobic digestion in the conventional Digesters, in the existing methods there is virtually no return on investment and consequently when there is no funding support the investment suffers, resulting in total loss and the lack of availability of sewage treatment services. The ecology and the environment is severely impacted, resulting in rise in pollution hazards.

US9127244B2 discloses digester assembly for providing renewable resources and associated systems, apparatuses and methods. A renewable energy system includes a digester assembly to anaerobically digest the liquid waste with microorganisms to supply renewable byproducts such as methane, hydrogen, carbon dioxide. US20020079266A1 discloses an integrated anaerobic digester system for converting animal waste, sewage sludge and other biodegradable feedstock into methane gas, carbon dioxide gas, ammonia, carbon black, organic acid, charcoal, a fertilizer. The system comprises a feedstock slurry feeder, a plurality of conduits connecting various components of the system and digester is pressurized to about 10 psi to form an enriched effluent and a discharge gas comprising at least methane during anaerobic digestion of the feedstock slurry.

FR1496288A discloses the method and apparatus for the treatment of waste water by anaerobic digestion of night soil. It relates to the treatment of water and sewage and management of di anaerobic waters sewer night soil. The method comprises transforming group I bacteria of fatty acids to water, methane gas to carbon dioxide. WO201048225A2 discloses a system and method for thermophilic anaerobic digester process to generate bio- methane from certain organic energy sources. The thermophilic anaerobic digester comprises a cylindrical vessel mounted horizontally above ground and sloped to maximize hydraulic plug flow and a mechanical agitator to propel inorganic material along the bottom.

Although state of the art offers several solutions to resolve the issue of sewage waste, however the scalability of the concepts has been a deterrent factor. The presently available digesters deviate from projections of scalability. The expected volume reduction of solids and productivity of gases is seldom met in available digesters.

OBJECT OF THE INVENTION

Accordingly, the main object of the present invention is to provide a scalable digester vessel for treatment of waste.

Yet another object of the present invention is to provide a digester vessel with unique arrangement of electrodes for efficient processing of the waste sludge and to minimize methanogenesis.

Yet another object of the present invention is to provide a digester that maximizes the hydrogen output.

Yet another object of the present invention is to provide a digester that provides for efficient and leak-proof collection of gaseous output.

Yet another object of the present invention is to provide a digester thatexpedites the process with the digestion time reduced to less than 10 days. It further reduces the spent sludge volume by 35 to 40%, which is a huge reduction of the spent sludge volume that involves handling and disposal costs.

Yet another object of the present invention is to provide a method of producing hydrogen which does not require the use of fossil fuels, which does not depend on the appearance of sunlight, and may be used to provide communities having relatively undeveloped electricity distribution and other energy infrastructures with a system that provides useful energy from collected wastes.

SUMMARY OF THE INVENTION

The present invention relates to a scalable design of a digester vessel for production of volume of gases for commercial application. It comprises a square or a rectangular vessel of industrial capacity, a plurality of aluminium and graphite electrodes to be used as cathode and anode respectively, outlets for gaseous outputs, and externally connected collection chambers for collecting gases. A typical direct current capable of generating a controlled electrical field is passed with the voltage approximately 2-3 volts and the current applied is around lOOamp. In another embodiment of the present invention, method of producing hydrogen and suppressing methane from anaerobically decomposed organic materials such as landfill material or sewage sludge by passage of an electric current. The electrical field thus created changes the anaerobic digestion process to thermophilic from methanogenesis period. The Hydrogen Gas volume is 65-70% of Electrical conversion efficiency. The process decrease the time required to process such materials.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described with reference to the following drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention:

Fig. 1 is a schematic illustration of a existing digester.

Fig. 2 is a top view of the frame in accordance with an embodiment of the present invention.

Fig. 3 is a top view showing equipment and piping in accordance with an embodiment of the present invention.

Fig. 4 A, 4B, 4C and 4D are the view of a digester in accordance with an embodiment of the present invention. Fig. 5A and 5B are the view of a raw gas holding tank in accordance with an embodiment of the present invention.

Fig. 6 A and 6B are the view of a H₂ gas holding tank in accordance with an embodiment of the present invention.

Fig. 7A, 7B and 7C are the view of an absorber in accordance with an embodiment of the present invention.

Fig. 8A, 8B and 8C are the view of a boiler in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. While the following description details the preferred embodiments of the present invention is not limited in its application to the details of construction and arrangement of the parts illustrated in the accompanying drawings.

With reference to the figures, numerical designation has been given for each element to facilitate the reader's understanding of the present invention, and particularly with reference to the embodiments of the present invention illustrated in the figures; various preferred embodiments of the present invention are set forth below. The enclosed description and drawings are merely illustrative of preferred embodiments and represent several different ways of configuring the present invention. Although specific components, materials, configurations and uses of the present invention are illustrated and set forth in this disclosure, it should be understood that a number of variations to the components and to the configuration of those components described herein and in the accompanying figures can be made without changing the scope and function of the invention set forth herein.

The present invention relates to a scalable design of a digester vessel for production of volume of gases for commercial application. Digester vessel comprises a square or a rectangular vessel of industrial capacity, a plurality of aluminium and graphite electrodes to be used as cathode and anode respectively, outlets for gaseous outputs, and externally connected collection chambers for collecting gases. A typical direct current capable of generating an electrical field is passed with the voltage approximately 2-3 volts and the current applied is around 100 ampere.

In an exemplary embodiment of the present invention the digester vessel consists of a square or a rectangular stainless steel vessel of 500gallon capacity. It is fitted with aluminium and graphite electrodes arranged in the form of an array that are used as cathode and anode of a typical direct current capable of generating an electrical field. The voltage is approximately 2-3 volts and the current applied is around lOOampere. The energy requirement of electrolysis of volatile acids is very small. The electrical field created changes the anaerobic digestion process to thermophilic from acidogenesis period. This leads to suppression of methane production and production of Hydrogen Gas and Carbon Dioxide. The Hydrogen Gas volume is 65-70% of electrical conversion efficiency. Carbon dioxide gas is approximately 30%and rest 5-10% is other gases. The arrangement of electrodes maximises the hydrogen output by 88.2%. The anaerobic digestion material consists of untreated sewage or sludge mostly containing domestic waste, industrial waste, hospital waste, laboratory waste, animal waste, and is usually designated as 2-10% BOD organic content. The more the organic content is, the better hydrogen production that results from it. The gases generated are a classic renewable energy source, and hydrogen gas produced when burnt the effluents are pure water no other pollutants.

The present invention uses anaerobic digestion where sludge is treated in three stages. In the first stage, hydrolysis takes place and enzymes in sludge convert higher molecular weight organic compounds into compounds suitable for use as a source of energy and cell carbon. In the second stage, acidogenesis takes place and bacteria known as acid- formers convert the compounds from the first stage into identifiable lower molecular mass intermediate compounds such as acetic acid and propionic.

Acid formers convert one molecule of glucose to three molecules of acetic acid as given in equation (1):

Conventionally, methanogenesis take place after acidogenesis where conversion of acetic acid to end products varies depending on whether methane formers or hydrogen formers predominate and end products formed are primarily methane and carbon dioxide.

Methane formers reaction is given in equation (2):

Hydrogen- formers reaction is given in equation (3):

After hydrogen is produced from hydrogen formers, still methanogens again interfere as given in equation (4):

Therefore, if methanogens are suppressed while acid-formers and hydrogen-formers are active in reaction with glucose, the resultant products i.e. hydrogen is generated from both the glucose and water is given in equation (5):

The present invention replaces methanogenesis by electrolysis where electric field is introduced in the sludge and resulting gas is mainly hydrogen and carbon dioxide with minor traces of other gases. The presence of an electric potential also suppresses the methane.

Electrolytic breakdown of acetic acid (and other carboxylic acids from fermentation of glucose) provides an alternative route for the final step to the production of hydrogen given by equation (6) - (8):

Fig. 1 shows existing digester in which suitable electrodes such as concentric electrodes receive intermittently applied voltage to influence solvated organic waste between the electrodes to produce hydrogen. In operation, voltage is applied by a voltage source to facilitate hydrogen generation and to prevent substantial methane production. Fig. 2 is a top view of the frame 10 made up of using ISMC 150 fabrication structure. Frame 10 is made up of materials such as but not limited to like mild steel (M.S.), stainless steel (S.S.), etc., with special coatings to prevent corrosion on the surface. Frame 10 is designed to accommodate the other supporting equipments like digester 20, raw gas holding tank 30, H₂ gas holding tank 40, absorber 50 and boiler 60.

Fig. 3 is a top view showing equipment and piping of systeml having, framelO made up of using ISMC 150 fabrication structure. FramelO is made up of materials such as but not limited to like mild steel (M.S.), stainless steel (S.S.), etc., with special coatings such as Fiber reinforced plastic (FRP) coating to prevent corrosion on the surface. FRP coating is a non-toxic highly cross-linked coating with exceptional chemical resistance to a wide range of chemicals and gases even at elevated temperatures. FRP lining can withstand temperatures up to 100 degrees centigrade, resistant to most of corrosive chemicals and protective to digester. Since the temperature of digester is maintained at 35 degree centigrade and sludge is highly toxic which corrodes the digester. So this special coating extends the life of digester. Frame 10 is designed to accommodate the other supporting equipments like digester20, raw gas holding tank30, H₂ gas holding tank40, absorber50 and boiler60. Digester20 is connected to raw gas holding tank via pipe70 and H₂ gas holding tank40 is connected to absorber50 via pipe80. Further, pumps90, 100 and 110 are provided to transfer the produced gas within the system. The raw gas obtained after the treatment in digester is majorly 92% H₂ by volume and 6% C0₂ by volume and remaining is methane (CH₄) which is collected in raw gas holding tank30 with the capacity of 485 Liters. TheH₂ gas holding tank40is connected to Digester20 and the raw gas from the digester 20first enters the raw gas holding tank30. Once the raw gas holding tank 30is full, a limit switch at the top of the raw gas holding tank30 sends signal to the booster blower to start and flow the raw gas from raw gas holding tank 30to absorber50 where 15% lean monoethanolamine (MEA) with water is sprayed from the top in the absorber50 at 45 Deg Centigrade. The lean monoethanolamine (MEA) captures the C0₂ and becomes rich monoethanolamine (MEA) (as it is now carrying C0₂) and rest of the gases in the absorber column50 mainly H₂ is transferred from top of the absorber 50to H₂gas holding tank40. The rich monoethanolamine (MEA) is then heated to 100 Degree Centigrade in boiler 60 where the C0₂ is released and same is captured in 1 m³ C0₂ balloon. The process continues till the limit switch keeps on sending signal to the booster blower for further processing as it indicates raw gas holding tank 30 is full.

Fig. 4 A, 4B, 4C and 4D are the view of a digester20 used in the system 1. Digester20 is squared in shape and made up of stainless steel 316 walls 112 and provided with angle iron supportll4 at the middle made up of stainless steel 304. Further a cover platell6 made up stainless steel 304 is provided to cover it from top. Inside digester20 there is an array of 5mm thick aluminium platesll8 and 12mm thick graphite platesl20 across them voltage will be applied using a voltage source. In order to feed in the sewage into digester20, an inletl34 is provided and to drain the digested material an outletl36 is provided. Further, the digester20 is provided with support standsl38 made up of ISMC 100 and have mounting plates at its end in mild steel. Further, the digester20 is provided with plurality of nozzles; nozzlel22 is used for mounting a pressure transducer to indicate pressure in sludge, nozzlel24 is used as gas outlet to transfer the raw gas from digester to raw gas holding tank 30, nozzlel26 is used for spraying monoethanolamine (MEA), when a signal is received for topmost level of sludge said signal being transmitted by level transmitter, nozzle 128 is for resistance temperature detector (RTD) to measure temperature of the sludge, nozzlel30 is for mounting pH sensor to measure the hydrogen-ion activity indicating its acidity or alkalinity and nozzlel32 is used to mount level transmitter which in turn records the bottom most level and/or low level of sludge in the digester tank.

Fig. 5A and 5B are the view of a raw gas holding tank30. A raw gas holding tank30 includes plurality of counter-weight pulley systeml40a, 140b and 140cwhich are in connection with the movable tankl44 assembled into the fixed tankl42. Both the tanks 142 and 144 are made up of stainless steel 304. Further, an inlet pipel48 and an outlet pipel46 are provided in fixed tankl42.When the gas in raw gas holding tank exceeds the capacity, it gets shifted to the movable tanks via counter- weight pulley systems.

Fig. 6A and 6B are the view of a H₂ gas holding tank40. A H₂ gas holding tank30 includes plurality of counter- weight pulley system 150a, 150b and 150c which are in connection with the movable tankl54 assembled into the fixed tankl52. Both the tanks 152 and 154 are made up of stainless steel 304. Further, an inlet pipel58 and an outlet pipe 156 are provided in fixed tank 152 when the gas in raw gas holding tank exceeds the capacity, it gets shifted to the movable tanks via counter- weight pulley systems.

Fig. 7A, 7B and 7C are the view of an absorber50used in the system. The absorber50 is provided with plurality of nozzles; nozzlel60 is for mounting funnel used for charging MEA solution, nozzlel62 is used for mounting level gauge to ensure the level of raw gas , nozzlel64 is used for draining, nozzlel66 is for mounting level transmitter to measure the continuous level of raw gas, nozzlel68 is used for connecting pump, nozzlel70 is used for spraying lean monoethanolamine (MEA) with water to capture C0₂, nozzlel72 is used for taking hydrogen gas out to H₂ gas holding tank 40, nozzlel74 is used for taking raw gas in from the digester 20 and nozzlel76 is for resistance temperature detector (RTD)to measure temperature of raw gases. Further, absorber50 is provided with a meshl78 in its circular bodyl80.

Fig. 8A, 8B and 8C are the view of a boiler60used in the systeml. The boiler60 is provided with a plurality of nozzles; nozzlel82 is used for taking carbon dioxide gas out and releasing it in C0₂ balloon, nozzlel84 is used for resistance temperature detector (RTD) to measure the temperature of rich monoethanolamine (MEA), nozzlel86 is used for spraying, nozzlel88 is for mounting level gauge to measure the level of rich monoethanolamine (MEA) and carbon dioxide gas released, nozzlel90 is used for draining, nozzlel92 is used for connecting pump, nozzlel94 is for resistance temperature detector (RTD) and nozzlel96 is used for mounting level transmitter for recording high and low level of carbon dioxide in tank. Further, boiler60 is provided with a meshl98in its circular body200; and two heaters of 1.5 KW each installed inside it to bring the temperature of MEA to 100 degree centigrade which releases C0₂.

EXAMPLE 1

TREATING AND TESTING SLUDGE SAMPLE

A day-wise test was carried out for 10 days in various batches. The digester vessel treats the untreated sludge and produces mixture of raw gases such as hydrogen, carbon dioxide. The example shows the test report of Batch -1. Day 1:- 1 Mixture of raw gases obtained after the treatment of sludge in digester vessel 20 gets filled in 6 raw gas holding tanks30 in 4 hours with a capacity of 485 litres for each tank. Therefore, the overall capacity of 6 raw gas holding tanks30 is 2910 litres. Thus, the sludge treatment leads to the mixture of raw gas of volume 2.91 mV day. The percentage of hydrogen production achieved is 0.17% which is 0.494 mV day.

1 day = 6 full tanks

1 tank capacity 485 litres

6 tank * 485 litres = 2910 litres

2910/1000 = 2.91 M3/day H2% = 0.17 %

2.91*0.17 = 0.494 M3/day

Day 2:-Same production as day 1 but percentage of hydrogen production rises to 0.60%. which is 1.314 mV day.

2.91*0.60 = 1.314 M3/day Day 3:- Mixture of raw gases filled in 4 raw gas holding tanks30 in 6 hours with tank capacity of 485 litres. The overall capacity of 4 raw gas holding tanks30 is 1940 litres. Thus, the sludge treatment leads to the mixture of raw gas of volume 1.94 mV day. The percentage of hydrogen production achieved is 0.71% which is 1.377 mV day.

1 day = 4 full tanks 4 tank * 485 litres = 1940 litres

1940/1000 1.94 M3/day

H2% 0.71 %

1.94*0.71 1.377 M3/day

Day 4:-Same production as day 3 but percentage of hydrogen production rises to 0.79%. which is 1.532 mV day. 1.94*0.79 1.532 M3/day

Day 5:- Mixture of raw gases filled in 3 raw gas holding tanks30in 8 hours with tank capacity of 485 litres. The overall capacity of 3 raw gas holding tanks30is 1455 litres. Thus, the sludge treatment leads to the mixture of raw gas of volume 1.455 m³/ day. The percentage of hydrogen production achieved is 0.83% which is 1.207 mV day.

1 day 3 full tanks

3 tank * 485 litres 1455 litres 1455/1000 1.455 M3/day

H2% 0.83 % 1.45*0.83 1.207 M3/day

Day 6:-Same production as day 5 but percentage of hydrogen production rises to 0.87%. which is 1.261 mV day.

1.45*0.87 1.261 M3/day

Day 7:-Mixture of raw gases filled in 2.5 raw gas holding tanks30 in 10 hours with tank capacity of 485 litres. The overall capacity of 2.5 raw gas holding tanks30 is 1212 litres. Thus, the sludge treatment leads to the mixture of raw gas of volume 1.21 mV day. The percentage of hydrogen production achieved is 0.88% which is 1.064 mV day.

1 day 2.5 full tanks

2.5 tank * 485 litres 1212 litres 1212/1000 1.21 M3/day

H2% 0.88 %

1.21*0.88 1.064 M3/day

Day 8:-Same production as day 7 but percentage of hydrogen production rises to 0.89%. which is 1.076 mV day. 1.21*0.89 1.076 M3/day Day 9:-Same production as day 8 but percentage of hydrogen production rises to 0.91%. which is 1.101 mV day.

1.21*0.91 = 1.101 M3/day

Day 10 :-Same production as day 9 but percentage of hydrogen production rises to 0.919%. which is 1.111 mV day.

1.21*0.919 = 1.111 M3/day

H2 Production : 11.528 M3

After the 10 day test it is found that the overall hydrogen production in batch -1 is 11.528 mV day.

Various parameters such as temperature conditions and electrode voltages supplied to electrodes for treating the sludge over the period of 10 days is listed in Table 2

Table 2

EXAMPLE 2 COMPOSITION OF HYDROGEN AND CARBON DIOXIDE GAS

A day-wise test was carried out for 10 days in various batches. The digester vessel treats the untreated sludge and produces mixture of raw gases such as hydrogen, carbon dioxide, nitrogen, oxygen. The example shows the test report of Batch -2.

Day 1:- Mixture of raw gases obtained after the treatment of sludge in digester vessel gets filled in 2 raw gas holding tanks30 with tank capacity of 485 litres. The overall capacity of 2 raw gas holding tanks30 is 970 litres. Thus, the sludge treatment leads to the mixture of raw gas of volume 0.97 m³/ day. The percentage of hydrogen production achieved is 0.24% which is 0.232 mV day.

1 day 2 full tanks 1 tank capacity 485 litres

2 tank * 485 litres 970 litres

970/1000 = 0.97 M3/day

H2% = 0.24 %

0.97*0.24 = 0.232 M3/day

Day 2:- Same production as day 1 but percentage of hydrogen production rises to 0.43%. which is 0.417 mV day.

0.97*0.43 = 0.417 M3/day

Day 3:-Same production as day 2 but percentage of hydrogen production rises to 0.62%. which is 0.601 mV day.

H₂% Rise at 0.62 %

0.97*0.62 = 0.601 M3/day

Day 4:- Mixture of raw gases obtained after the treatment of sludge in digester vessel 20 gets filled in 1.5 raw gas holding tanks30 with tank capacity of 485 litres. The overall capacity of l.5raw gas holding tanks30 is 727.5 litres. Thus, the sludge treatment leads to the mixture of raw gas of volume 0.72 m³/ day. The percentage of hydrogen production achieved is 0.73% which is 0.525 mV day.

1 day 1.5 full tanks

1 tank capacity 485 litres

1.5 tank * 485 litres 727.5 litres

727.5/1000 0.72 M3/day

¾% 0.73 %

0.72*0.73 0.525 M3/day

Day 5 :-Same production as day 4 but percentage of hydrogen production rises to 0.78%. which is 0.561 mV day.

0.72*0.78 0.561 M3/day

Day 6:-Same production as day 5 but percentage of hydrogen production rises to 0.84%. which is 0.604 mV day. 0.72*0.84 0.604 M3/day

Day 7:-Same production as day 6 but percentage of hydrogen production rises to 0.85%. which is 0.612 mV day.

0.72*0.85 = 0.612 M3/day

Day 8:-Same production as day 7 but percentage of hydrogen production rises to 0.87%. which is 0.6264 mV day.

H₂% Rise at 0.87 %

0.72*0.87 = 0.6264 M3/day

Day 9:- Mixture of raw gases obtained after the treatment of sludge in digester vessel20 gets filled in 1 raw gas holding tanks30 with overall tank capacity of 485 litres. Thus, the sludge treatment leads to the mixture of raw gas of volume 0.48 mV day. The percentage of hydrogen production achieved is 0.88% which is 0.422 mV day.

1 day 1 full tanks

1 tank capacity 485 litres

1 tank * 485 litres 485 liters

485/1000 0.48 M3/day

H2% 0.88 %

0.48*0.88 0.422 M3/day

Day 10:-Same production as day 9 but percentage of hydrogen production rises to 0.88%. which is 0.422 mV day.

0.48*0.88 0.422 M3/day

H₂ Production: 5.022 M3

After the 10 day test it is found that the overall hydrogen production in batch -2 is 5.022 mV day.

Various parameters such as temperature conditions and electrode voltages supplied to electrodes for treating the sludge over the period of 10 days is listed in Table 3. Table 3

EXAMPLE 3

SLUDGE TEST AND GAS ANALYSIS

A sludge sample- 1 is tested for its composition and contents using standard test methods are:3025 P-l 1-1984, APHA 22^nd edition, SRTL/SOP/19 and results obtained are presented in T able 4.

TABLE 4

A sludge sample-2 is tested for its composition and contents using standard test methods IS:3025 P-11-1984, APHA 22^nd edition, SRTL/SOP/19 and results obtained are presented in table 5.

TABLE 5

The gas analysis report after the treatment of sludge by GC-MS test is given in Table 6:

TABLE 6

Therefore, the hydrogen obtained is 69.42%. In another preferred embodiment of the present invention, the scaled version of the Digester for commercial application is made of reinforced concrete walls. This is economically advantageous as contain costs of typical Sewage Treatment Plants.

In an alternative embodiment of the present invention, the electrical energy is generated using renewable energy sources like solar energy, wind energy, hydropower, to arrive at self-sustained process. This further reduces the cost of Hydrogen Gas production. The cost of production is thus further reduced by the renewable energy source.

Claims

CLAIMS We claim:

1. A system for treating sewage comprising: a frame (10); a scalable digester (20), a raw gas holding tank (30), a hydrogen gas holding tank (40), an absorber (50) with a mesh(l78), and a boiler (60) with a mesh (198); wherein, said digester (20) comprises of walls (112) with at least one inlet (134) to feed sewage to be digested, at least one outlet (136) to drain digested sewage, a plurality of nozzles, an array of electrodes and pumps (90,100,110), said digester (20) being connected to the raw gas holding tank (30) via a pipe (70); the hydrogen gas holding tank (40) is connected to said absorber (50) via a pipe (80); the digester (20) treats the sewage through hydrolysis, acidogenesis and electrolysis producing hydrogen while suppressing methanogenesis; and the array of electrodes increases hydrogen output by 88.2%.

2. The system as claimed in claim 1, wherein the walls (112) are made of material including but not limited to stainless steel and reinforced concrete.

3. The system as claimed in claim 1, wherein said frame (10) is made up of a material not limited to mild steel, stainless steel and coated with fiber reinforced plastic material (FRP) to withstand high temperature and provide resistance to corrosion.

4. The system as claimed in claim 1, wherein said electrodes are given a direct current in the range of 2-3 volts.

5. The system as claimed in claim 4, wherein the direct current is generated using renewable energy sources like solar energy, wind energy, hydropower.

6. The system as claimed in claim 1, wherein said array of electrodes comprises anodes made preferably of aluminium plates (118) having thickness of 5 mm and cathodes made preferably of graphite plates (120) having thickness of l2mm.

7. The system as claimed in claim 1, wherein the nozzles are used for mounting pressure indicator (122), gas outlet (124), for spraying (126), for resistance temperature detector (128), for mounting pH sensor(l30) and mounting level transmitted! 32) for recording high and low level in tank.

8. The system as claimed in claim 1, wherein the raw gas holding tank (30) comprises a plurality of counter weight pulley system (l40a ,l40b, l40c) in connection with a movable tank (144) assembled into a fixed tank (142) with inlet pipe (148) and outlet pipe (146).

9. The system as claimed in claim 1, wherein the hydrogen gas holding tank comprises of plurality of counter weight system (l50a, l50b, l50c) in connection with movable tank (154) assembled into fixed tank (152) with inlet pipe (158) and outlet pipe (156).

10. The system as claimed in claim 1, wherein the absorber (50) includes a plurality of nozzles for mounting funnel (160), for mounting level gauge (162), for draining (164), for mounting level transmitter (166), for connecting pump (168), for spraying (170), for taking hydrogen gas out (172), for taking raw gas in (174) and for resistance temperature detector (176).

11. The system as claimed in claim 1, wherein the boiler(60) includes a plurality of nozzles for taking gas out (182), for resistance temperature detector (184, 194), for spraying (186), for mounting level gauge (188), for draining (190), for connecting pump (192), for mounting level transmitter (196).