Title of Invention

"A PROCESS FOR BIOMETHANATION OF ORGANIC WASTE AND AN APPARTUS THEREFOR"

Abstract

This invention relates to a process for the biomethanation of organic waste. According to the process the organic waste is first digested in the presence of water to extract the organic acids and in the absence of the addition of microbes to the biomass. The leachate obtained after the first step is subjected to a second step of digestion in the presence of methanogenic consortium to obtain methane gas. Also this invention relates to an apparatus for carrying out the process of biomethanation of organic waste. The apparatus has a solid bed reactor having an inlet for introduction of water to produce a leachate comprising essentially of organic acids. A storage tank for receiving the leachate and wherein the pH of the leachate is adjusted to a neutral pH. A second reactor having a gas outlet is provided for receiving said leachate from the storage tank.

Full Text

FIELD OF INVENTION This invention relates to a proc.ess and apparatus for biomethanation of organic waste„ BACKGROUND OF THE INVENTION The disposal of municipal solid waste & orqanic waste presents a serious problem in developing countries because of the harmful environmental effects associated with it„ known processes consist in introducing the or panic waste into a reactor and the process of fermentation or digestion takes place in the presence of an inocu„ H disadvantage associated with such a known process is the formation of scum,, Such a scum 'forms an upper layer" and prevents a further digestion and release of biogas,, Agitation of the slurry cannot be efficiently effected in view of the volume o f the slurry„ Thus ,, anotherr method known in the art is that of the pretreatment of the orqanic or leafy biomass waste,, Thus,, the waste is preshaved and pulverized to effect, a size reduction,, However, such a step contributes to the end cost of the process,, Thus, the known processes are associated with various limitation such as large area requirement , emission of toxic material and high energy requirement. Even by adequate shredding to cut the fibrous portion, the scum formation can be delayed but not completely eliminated . Continuous stirring of the material requires additional power and in large scale it is even more difficult to maintain a homogeneous mixture. Periodical removal of the scum is also done in certain designs. Such problems will not arise in the present design since there is extraction of soluble organic material in the initial stage and hence no additional arrangements needed for preventing the floating problem associated with the lighter materials. OBJECTS OF THE INVENTION An object of this invention is to propose a novel process and apparatus for biomethanation of organic waste. Another object of this invention is to propose a process and apparatus for bimethanation of preparation is not needed which requires a pretreatment process such as shredding to fine particle size and mixing of sold with water. Still another object, of this invention is to propose a process and apparatus for biomethanation of organic waste and wherein a scum layer is no longer for med„ Yet another object of this invention is to propose a process and apparatus for biomethanation of organic waste and wherein the retention time for d iciest ion is reduced,, A futhers object of this invention is t o propose a process and apparatus for biomethanation of organic waste and which operates at. high total solids c: o n c e n t. r a t i o n „ A still further object of this invention is to propose a process and apparatus for biomethanation of organic waste which utilizes a low water requirement in comparison to the conventional apparatuses,, Yet a further object of this invention is to propose a process and apparatus for biomethanation of organic waste which produces a high quality organic manure DESCRIPTION OF. THE_ INVENTION According to this in vent, ion there is provided a process for the biomethanation of organic waste which comprises in a first, step of disgestion of the organic waste in the presence of water to extract the organic acids. in the absence of the addition of microbes to the biomass, subjecting the leachate obtained by the first step of digestion to a second step of digestion in the presence of methanogenic consortium to obtain methane a as,, Further ace:: or ding to this invention there is provided an apparatus for carrying out the process of biomethanation of organic: waste comprising a solid bed reactor having an inlet for introduction of water to produce a leachate comprising essentially of organic acids. a storage tank for receiving the leachate and wherein the pH of the leachate is ad lusted to a neutral pH,, a second reactor for receiving said leachate from the storage tank,, said second reactor having a gas outlet,, In ace: or dance with this invention,, the organic waste material is packed into a solid bed reactor. In distinction to the known art, the solid waste material does not require a ore treat merit of shaving and pulverization. Water is introduced into the reactor at. a controlled rate of 0=5 1/m to 1,,5 1/m. The leachate from the reactor is fed to a tank through a collector. and where the pH is raised by addition of alkali. The 1eachate is then fed to an up flow anaerobic sludge blanket reactor and wherein a digestion is caused in the presence of an inoculum. DESCRIPTION OF INVENTION WITH REFERENCE TO DRAWINGS Further objects and advantages of this invention will be more apparent "from the ensuing description when read in conjunction with the accompanying drawings and wherein s shows a schematic view of the apparatus for carrying out. the process of the present invention, and Fig,, 2 shows the solid bed reactor employed in the apparatus of fig,, 1,, Referring to the drawings, and with particular reference to fig,, 1 , the apparatus comprises solid bed reactor' 1 for digestion of the leafy biomass waste,, Microbes are not introduced into reactor .1. and,, instead the microbes Present in the biomass is used for the step of digestion. Water is added to reactor" through a spray la so as to enhance the leaching process,, The step of digestion is continued for a period of approximately 7 days and till the acid concentration and COD becomes constant. The leachate formed by the step of digestion essentially consists of organic acids which is introduced into collector 2 from reactor .1 The leachate from collector 2 is introduced into a storage tank 3 and where the pH is increased to a neutral pH „ Though fig,, 1 illustrates a collector 2., the leachate from reactor 1. may be introduced directly to collector 3 from reactor 1„ A pump 4 is connected to the outlet of storage tank 3 so as to pump the effluent to an up flow anaerobic, sludge blanket reactor 5 in which microbes are introduced so as to produce methane gas The microbes introduced into reactor 5 are methanogenic consortium Reactor" 5 has a lied 6 of stone chips so as to uniformly distribute the effluent or leachate within said reactor,, When leachate is introduced through inlet 12 of reactor 5,, microbes act on it so as to cause a further step of deoradation ,, and the organic acid present in the leachate further breaks down into methane gas and CO2 which escape through outlet 8.. The exhaust 1 each at. e1 is collected 'from liquid outlet 9,, As shown in Fiq., I,, solid bed reactor 1 is connected to a reservoir .1(3 through a pump 11,, Thus, the organic acid formed by the step of digestion in solid bed reactor 1 is recycled through reservoir 10 so as to increase the concentration of the acid,, Reactor 5 has a temperature control system comprising a heat convector 7 connected to a heat convector control system 13,, A temperature monitor 14 is connected to a thermocouple 15. Reference is now made to Fig,, 2, which illustrates the solid bed reactor to comprise a reactor .1 covered by a lid 16. A pipe 17 connects a sprinkler la to a water source so as to enhance the process. The biomass is supported on a perforated base 1.8,, which can be slided. A water seal 19 is provided at the upper end of reactor 1. Reactor 1 is supported on Reservoir 10. A pump 11 connects reservoir reactor 1 so as to recyle -the acid and thereby increase its concentration,. A level indicator 20 is provided with reservoir 10. WE CLAIM: 1,, A or"ocess for the biomethanation of organic waste which comprises in a first step of digestion of the organic waste in the presence of water to extract the organic acids,, in the absence of the addition of microbes to the biomass,, subjecting th e leacha t e obtained by the first step of digestion to a second step of cli.qest.ion in the presence of methanogenic consortium to obtain methane gas,, 2,, A process as claimed in claim 1 wherein the pH of the 1eachate from the first step of digestion is ad lusted to a neutral pH „ 3,, A process as claimed in claim 1 wherein the leachate from the first step of digestion is recycled so as to .increase the? concentration of the organic acid,, 4,, A process for the biomethanation of organic waste substantially as herein described and illustrated. 5,, An apparatus for carrying out the process of biomethanation of organic waste comprising a solid bed reactor having an inlet for introduction of water to produce a leachate comprising essentially of organic acids, a storage tank for receiving the leachate and wherein the pH of the leachate is adjusted to a neutral pH,, a second reactor for receiving said leachate from the storage tank, said second reactor having a gas out. 1 et „ 6,, An apparatus as claimed in claim 5 wherein said second reactor is an upflow anaerobic sludge blanket reactor„ 7,, An apparatus as claimed in claims 5 & 6 wherein said second reactor has a bed of stone chips at or in the proximity of the base so as to uniformly distribute the leachate therein . 8,, An apparatus as claimed in claims 5 & 6 comprising a collector provided between said solid bed reactor" and storage tank. 9,, An apparatus as claimed in claim 5 comprising a reservoir disposed below of said solid bed reactor, a sliding door provided with said reactor' so as to be in flow communication with the storage tank. 10,, An apparatus as claimed in claim 9 comprising a pump connected to said storage tank so as to allow a rec ircu la t. ion of the leachate into said solid bed reactor, 11,, An apparatus for carrving out the process of biomethanation o f organic waste substantially as herin described and illustrated.,

Documents:

2655-del-1997-abstract.pdf

2655-del-1997-claims.pdf

2655-del-1997-correspondence-others.pdf

2655-del-1997-correspondence-po.pdf

2655-del-1997-description (complete).pdf

2655-del-1997-drawings.pdf

2655-del-1997-form-1.pdf

2655-del-1997-form-13.pdf

2655-del-1997-form-19.pdf

2655-del-1997-form-2.pdf

2655-del-1997-form-3.pdf

2655-del-1997-form-5.pdf

2655-del-1997-form-6.pdf

2655-del-1997-gpa.pdf