Title of Invention

A PROCESS FOR PRODUCTION OF BIOGAS FROM BRIQUETTES OF FRUIT AND VEGETABLE PROCESSING WASTE

Abstract A process for production of biogas from briquettes of fruit and vegetable processing waste which comprises (a) dissolving the briquette of fruit and vegetable processing waste in water to make a homoginised slurry, (b) characterized in that feeding the above said homoginised slurry obtained in step(a) to an anaerobic digester at a loading rate ranging from 6 to 18%, (c ) feedling the slurry to the said digester at hydraulic retention time (HRT) ranging between 35 to 60 days, (d) recovering the biogas from the digester.
Full Text The present invention relates to a process for production of biogas from briquettes of fruit and vegetable processing waste.
The process relates to a novel aspect of using briquettes made from fruit and vegetable processing wastes for biogas generation, thereby solving the waste disposal problems in fruit and vegetable processing industries.
Of all the alternative energy sources studied in recent years, biogas production appears to be the most favoured, especially when the feedstock is agro- industrial and fruit and vegetable processing wastes. In addition to energy generation, it reduces pollution. Both the liquid and solid residues may be utilised for aquaculture, and animal and poultry feeds.
Anaerobic digestion of wastes from process plants is the only simple method which can be readily operated at farm, domestic and community levels for fuel production. The annual availability of these wastes amounts to 1050 million tonnes. A major portion of these wastes is mostly discarded and thus becomes a source of pollution. In some cases, disposal becomes expensive because of the high cost of transportation.
The majority of wastes from the fruit and vegetable processing industries are seasonal, and as they decompose rapidly, they are available for only a limited period of 2-4 months. The use of fruit and vegetable wastes as feed material in an anaerobic digester makes this process highly economical for the production of biogas.
This process becomes helpful when the installation of biogas digesters is not possible in the site where the waste is generated. In such cases, the briquettes can be either transported to places where biogas digesters are installed or briquettes can be sold to people who own biogas digesters.
Due to the increasing fertilizer value of the conventional feed materials for the biogas digesters like animal/poultry excreta, usage of such materials are no more economical to generate biogas. Moreover, there is acute shortage of such feed materials. Hence, the briquettes can be used as an alternate feed material, and the yield of biogas is also more in the case of fruit and vegetable waste, than the conventional feed material. Briquetted wastes can easily be transported to other places where acute shortage of other fuels is a problem. Biogas digesters can be installed at such places and briquettes can be used as the feed materials.
Reference may be made to Lane (1979) wherein fruit and vegetable waste is used for methane generation. Overloading of digesters with citrus processing wastes above 4 kg/m3/day is reported to result in a fall in pH and gas yield and an increase in the CO2 gas content produced.
Reference may be made to Gollakota et al. (1983) wherein biogas production by anaerobic digestion of oil cake by a mixed culture isolated from cow dung is reported. Starting with cow dung, a mixture capable of producing biogas by the anaerobic digestion of castor cake has been isolated and stabilised.
Reference may be made to US Patent 4,935,038 (Wolf et al., 1990),' wherein the process for recovery of usable gas from garbage is described. The garbage is pressed into pellets in a range of 1 -50 mm and were dried to a maximum moisture of 25%. The heavy vegetable fraction of the garbage is taken to a biomass converter in which it is used to generate methane gas.
Reference may be made to Madhukara et al. (1993) wherein ensilaging of mangopeel Is used for methane generation. Ensilaging of mangopeel for six months, the effect of ensilage on its physico-chemical characteristics and methane generation by an anaerobic digestion process were studied. The ensilaged mangopeel is found to be useful substrate for anaerobic digestion for methane generation, and the biogas yield is as high as 0.68 m3/kg VS added with a methane content of 52%.
Reference may be made to Srilatha et al. (1995) wherein fungal pretreatment of orange processing waste by solid state fermentation for improved production of methane is reported using strains of Sporotrichum, Aspergillus, Fusarium and Penicillium. Fungal pretreatment improved overall production of biogas yield of 0.5-0.6 m3/kg VS added at a loading rate of 8% with a hydraulic retention dme of 25 days.
Reference may be made to Griffin et al. (1998) wherein an aggressive start up strategy is used to Initiate codigestlon in two anaerobic, continuously mixed bench top reactors at mesophilic and thermophilic conditions. Methanobacteriacea
were the most abundant hydrogenotropic methanogens in the digesters tested, but
their levels were higher in the thermophilic digester.
Reference may be made to Zayed and Winter (2000) wherein a whey
solution is used as a substrate for methane production in an anaerobic fixed bed
reactor at a hydraulic retention time of 1 0 days, equivalent to a space loading of
3.3 kg m 3/ day. 90% of the chemical oxygen demand is converted to blogas.
The technical know how of briquettes made up of fruit and vegetable processing wastes to be used for biogas production is not established so far.
The main object of the present invention is a process for preparation of biogas production from briquettes of fruit and vegetable processing waste.
Accordingly, the present invention provides a process for production of biogas from briquettes of fruit and vegetable processing waste which comprises
(a) dissolving the briquette of fruit and vegetable processing waste in water to make a homoginised slurry,
(b) characterized in that feeding the above said homoginised slurry obtained in step(a) to an anaerobic digester at a loading rate ranging from 6 to 18%,
(c ) feedling the slurry to the said digester at hydraulic retention time (HRT)
ranging between 35 to 60 days,
(d) recovering the biogas from the digester.
Before going into the description of present invention, in our copending application number 437/DEL/2001 a binder composition for use in forming briquettes from fruit and vegetables processing waste with method of forming briquettes has been described.
in yet another embodiment, the loading rate of briquettes may be from 6-18%.
In yet anotlier embodiment, the HRTs may be in the range of 30-50 days.
In yet another embodiment, the biogas yield may be 0.60m3 to 0.89m3 per kg VS added.
In yet another embodiment, the methane gas production may be 56 to 68%.
The briquetted fruit and vegetable wastes lack the bacteria which are needed for anaerobic digestion. Initially 100-150 litre cowdung slurry prepared by diluting the cow dung with water in the ratio of 4:5 is fed to the digester. Start up studies were initiated by using 5% v/v of starter cultures collected from fruit and vegetable fed operated digesters of 1.5 m3 and sewage and sludge samples. These digesters were left undisturbed for 15 days at 300C and the total biogas, methane, carbon dioxide and pH were determined every day. It is evident that in the beginning of these investigations, the gas production is almost negligible and continued for 15 days, and thereafter the gas yield increased. After two weeks, the digesters were fed with the cow dung and homogeneous briquettes slurry in the proportions of 80:20, 60:40, 40:60, 20:80, and 0:100 for a week, each for five successive weeks at different hydraulic retention time (HRT) with different loading rates.
Experiments were carried out in a series of 1.5 m3 biodigesters working equipped with inlet for feeding and outlet for discharging the effluent. These
digesters were also provided with an outlet for biogas. The digesters were fed once in a day and gas production is measured by the wager displacement method or by a Toshniwall Gas flow meter. Composition of the gas produced is analysed by using CIC gas chromatograph using Chromosorb column, equipped with a thermal conductivity detector, using a Porapaq Q column, with an oven temperature of 600C.
Total solids, volatile solids, volatile fatty acids, ash, cellulose, hemicellulose, pectin, protein, non-reducing sugars, reducing sugars, lignin, and C/N ratio and pH were analysed weekly once according to the method of American Public Health Association (Tablet).
After achieving the steady state of the digesters, the effect of loading rate of briquettes on biogas and methane production is investigated. Different loading rates tried in this set of investigations were 4- 12% of briquettes. The maximum gas yield and methane production is observed at 4-8% of loading rate, and declined markedly thereafter. After achieving the maximum gas yield and methane content at 4-8 % of loading rate, different hydraulic retention time (HRT) were tried from 10-50 days.
After achieving the steady state of the digesters, the effect of hydraulic retention rate of briquettes on biogas production and methane content is carried out. Different HRTs tried in this experiment were 10-50 days. The maximum gas yield and methane is observed at 40-50 days of HRT, and declined thereafter.
The novelty in the present invention is use of briquettes from fruit and vegetable processing wastes for biogas production.
Table 1. Composition of briquette of fruit and vegetable processing wasted used for biogas production
(Table Removed)
The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention.
EXAMPLE 1
The briquettes of fruit and vegetable wastes were mixed In sufficient quantity of water and made it into a homogenous slurry. The pH Is adjusted to 7.0. The slurry is fed to the 1.5 m3 anaerobic digester at different loading rates of 4-12% of briquettes. These digesters were operated in a semi-continuous mode of operation by loading once In every 24 hours. Biogas yield and the methane content were calculated at every 24 hours. Anaerobic digestion is carried out with different loading rates of 4-12% of briquettes (Table 2). The digester is operated for 2 months for each loading rate and when it attained again steady state, it is further operated for the subsequent higher loading rate In the increasing order. There is a good correlation between the yield of biogas and methane with the substrate utilised. Between 2-12% of loading the biogas yield varied in the range of 0.41 to 0.89 per kg VS added, and the methane content ranged from 41-68%. At higher loading rates of 10-12%, there Is a marked decline in the yield of biogas with a low methane content. The specific rates of gas production increased with a gradual increase in the loading rates from 2-12 kg TS m3/day and decreased thereafter. During this period, the pH ranged from 6.0 to 7.0.
Table 2: Influence of loading rate on biogas yield, methane
(Table Removed)
The yield is highest however, at the loading rate of 6-8% and then decreased gradually. This is associated with a drop in pH at higher loading rates and consequently increased levels of VFA. The methane production increased during the start up of anaerobic digestion. As the methane content increased, there is concomitant decrease in the amount of carbon dioxide produced.
EXAMPLE 2
The briquettes of fruit and vegetable processing waste is mixed in sufficient quantity of water and made it into a homogenous slurry. The slurry is fed to a 1.5 m3 digester. The influence of different HRTs on anaerobic digestion is observed. Gas production is found to be less at 15 days HRT and below bringing about a marked deterioration in the overall performance of the digester. The yield of biogas and its methane content at 20 days HRT were 0.45 m3/kg VS added and 45% respectively (Table 3). After 20 days of HRT, biogas yield and methane content
started increasing slowly. At a loading rate of 6-8%, TS/m3 day, the maximum yield of biogas and methane is obtained at 40 to 50 days HRT. The yield of biogas and methane were found to be 0.60-0.83 m3/kg VS added and 56-68% at 40 to 50 days of HRT respectively. At higher HRTs, inhibition of biogas yield and the rate of biogas production is observed. At lower and higher HRTs, there is decrease in the yield of biogas and methane content. The inhibition of biogas generation at higher HRT is associated with the increase in the level of VFA in the digesters and the consequent lowering of pH.
Table 3. influence of HRT on biogas yield, methane
(Table Removed)
The main advantages of the present invention are
1. The briquettes can be used as an alternate feed materials for biogas digesters where conventional materials like animal/poultry excreta is used.
2. This process invites less investment for the waste disposal problems.
3. This method can be employed when the installation of biogas digesters at the site is not feasible, or not even possible due to the space constraints.
4. The briquettes can easily be transported to other places where acute shortage of other fuels is a problem.
5. The yield of biogas is more in the case of briquettes made from fruit and vegetable waste than the conventional feed material.





We claim
1. A process for production of biogas from briquettes of fruit and vegetable processing waste
which comprises
(a) dissolving the briquette of fruit and vegetable processing waste in water to make a homoginised slurry,
(b) characterized in that feeding the above said homoginised slurry obtained in step(a) to an anaerobic digester at a loading rate ranging from 6 to 18%,
(c ) feedling the slurry to the said digester at hydraulic retention time (HRT) ranging between
35 to 60 days,
(d) recovering the biogas from the digester.
2. A process as claimed in claim 1 wherein the loading rate of briquettes is preferably in the range of 6 to 12%.
3. A process for production of biogas from briquettes of fruit and vegetable processing waste, as herein described with reference to examples accompanying the specifications.

Documents:

436-del-2001-abstract.pdf

436-del-2001-cancelled claims.pdf

436-del-2001-claims.pdf

436-del-2001-complete specification(granted).pdf

436-del-2001-correspondence-others.pdf

436-del-2001-correspondence-po.pdf

436-del-2001-description (complete).pdf

436-del-2001-form-1.pdf

436-del-2001-form-18.pdf

436-del-2001-form-2.pdf

436-del-2001-form-3.pdf


Patent Number 242406
Indian Patent Application Number 436/DEL/2001
PG Journal Number 35/2010
Publication Date 27-Aug-2010
Grant Date 25-Aug-2010
Date of Filing 30-Mar-2001
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG NEW DELHI-110001,INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 DASARI SWAROOPA RANI DEPARTMENT OF FOOD MICROBIOLOGY CENTRAL FOOD TECHNOLOGICAL RESEARCH INSTITUTE,MYSORE,INDIA.
2 KRISHNA NAND DEPARTMENT OF FOOD MICROBIOLOGY CENTRAL FOOD TECHNOLOGICAL RESEARCH INSTITUTE,MYSORE,INDIA.
PCT International Classification Number C12P 065/02
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA