4. DESCRIPTION
Field of the Invention
The present investigation relates to a method of producing bioethanol from biomass (agricultural waste residues) especially from region specific crops that are not used either as food or fodder and not given much importance and thrown as a common waste.
Background of the Invention
Process for bioethanol production has been established earlier. The method included digestion of biomass (food crops like barley, sweet sorghum, maize straw etc.) with 70% acid pre-digestion followed by 40% acid digestion (Sun, Y. and Cheng, J. 2004, Biores. Technol S3: 1-11). The process, however, might have some undesirable effects; The formation of aldehydes such as furfural via the degradation of the produced monosaccharide is essentially inevitable in this process; this in turn lowers the conversion yield of polysaccharides and inhibits the ethanol fermentation process (Palmqvist, E. and Hahn- Hagerdal, B. 2000, Bioresour. Technol. 74: 17-24). As an additional problem, sulfuric acid used at such high percentages might corrode the reaction vessels. The recovery of the spent acid or neutralization of the acid also complicates the down streaming processing steps (Teramoto, Y., Lee, S. H., Endo, T 2009, Bioresource Technol. 100: 4783-4789). The earlier methods also iincluded alkali pretreatment on treatment with sodium hydroxide which led to inhibition of yeast activity (Chen, Y., Sharma, R.R, Keshvani, d., and Chen, C, 2007, Appl. Biochem. Bioethanol. 142: 276-290).
An additional technology also involved using enzymes such as cellulose for digestion of cellulose to convertible sugars (Wu, M.M., Chan;, K., Gregg, D.J., Boussaid, A., Beatson, R.P., Saddler, J.N. 1999, Appl. Biochem. and Biotechnol, 77-79, 47-54. But these enzymes did not prove to be cost effective.
Thereby the objective of the present investigation is to produce ethanol efficiently from agricultural wastes. Our method involves 2% acid digestion which solves the problem of neutralization and causes no hindrance in yeast activity. Thereby giving rise to an economic method.
Summary of the Invention
The objective of the present investigation is to producing bioethanol from biomass (agricultural waste residues) especially from region specific crops. Our process is as follows:
a) Chemical pretreatment for digestion of agricultural waste biomass,
b) Estimation of total and reducing sugar
c) Filtration and neutralization,
d) Estimation of lignin content,
e) Fermentation,
f) Distillation and estimation of alcohol in the distillate and
g) Calculation of percentage yield of alcohol.
The process adopted is therefore, a simple and economical method for the production of bioethanol
from agricultural waste biomass.

Detailed Description of the Invention:
Any waste biomass of agricultural origin can be processed by the process of the present invention. The method is especially suitable for the hydrolysis of agricultural waste that contains hemicellulose and lignin in various quantities in the raw material. In this case, the residue left behind after acid pretreatment can be used as bio-adsorbent. The residue left after neutralization of acid hydrolysate can be used in the cement industry. Each step in the process is conducted as per standard norms. The process adopted for the production of bioethanol is now explained below:
a) Biomass weighing lOg (w/w) is treated with 300 ml of 2% sulphuric acid and subjected to high pressure (15 psi) digesting at 120" C for 10 min and further digesting for 1.5 hrs at 90° C is continued
b) The solubiJized sample is cooled to room temperature and filtered through Whatman 1 filter paper.
c) The total sugar and reducing sugar content in the filtrate is estimated, which will be end product of hydrolysis of cellulose and hemicellulose.
d) Undigested lignin mass remaining on filter paper is oven dried and weighed to find out the proportion of hgnin to cellulose and hemicellulose in the biomass under study.
e) The filtrate is neutralized with thick slurry of calcium hydro.\ide until it reaches the pH of 6.0.
0 The neutralized filtrate is allowed to remain overnight at room temperature for settling.
g) The supernatant is filtered once again through Whatman I filter paper.
h) The filtrate is inoculated with yeast granules {Saccharomyces cerevisiae) at a concentration
of 0.5g/lt,2.5g/lt,5g/lt,7.5g/lt and lOg/lt and subjected to fermentation at 30V in shaker
incubator maintained at 125 rpm for 48 hrs. i) The fermented sample is subjected to distillation in rotary flask evaporator at TS^C. j) The ethanol in the distillate obtiained fi-om the fermented hydrolyzate of the biomass is
estimated by titrimetric method using potassium dichromate against, potassium iodide
sodium thio-sulphate with starch as indicator and using absolute alcohol at 1.2mg/ml
concentration as standard, k) The percentage yield of ethanol per kg of biomass is calculated considering the equation
CeHuOe C2H5OH + 2 CO2 wherein 180 g of glucose produces 92 g of alcohol, thereby
the alcohol percraitage is calculatesd corresponding to the reducing sugar contait.
Results:
a) Total sugar content in dry areca nut fiber, fresh arecanut fibre, dry coconut fiber, fresh coconut fibre, dry coffee, wet coffee, dry arecanut and coconut fibres, fi-esh arecanut and coconut fibres, weed and rice husk was found to be 6.12, 2.31, 10.41, 2.06, 5.5, 0.48, 3.25, 2.43,2.37 and 4.25 X 10"-3g per ml of hydrolyzate respectively.
b) The reducing sugar content for the above referred biomass inputs-3per ml of hydrolyzate respectively.
c) The percentage yield of bioethanol per kg of biomass for the above referred biomass input was found to be 52.16, 19.26, 16.06, 47, 46.33, 22.46, 49.29, 19.01, 13.4 and 40.26 respectively.

We claim that:
1. The process adopted for Bioethanol production from various types of biomass can be effectively used for commercial production. This process comprises of (a) Chemical pretreatment for digestion of agricultural waste biomass, (b) Estimation of total and reducing sugar, (c) Filuration and neutralization, (d) Estimation of lignin content (e) Fermentation, (0 Distillation and estimation of alcohol in the distillate and (g) Calculation of percentage yield of alcohol.
2. The biomass referred in claim I includes dry areca nut fiber, fresh arecanut fibre, dry coconut fiber, fresh coconut fibre, dry coffee, wet coffee pulp, dry arecanut and coconut fibres mixture, fresh arecanut and coconut fibres mixture, weed and rice husk.
3. The process according step (a) of claim 1, digests the raw material in 2% sulfuric acid to solubilize cellulose, hemicellulose and separate insoluble lignin from the biomass.
4. The process according step (b) of claim 1, produces solubilized cellulose and hemicellulose from the biomass.
5. Further, the process according to step (b) of claim 1, gives rise to filtrate in which total and reducing sugar content are estimated, which is the end product of hydrolysis of cellulose and hemicellulose
6. According to step (c) of claim 1, the filtrate is neutralized with calcium hydroxide to pH 6.0
7. According to step (d) of claim 1, the solid mass left on the filter paper is oven dried to find out the lignin mass in proportion to hemicellulose and cellulose in the biomass used, which is already hydrolysed as indicated in step (a) of claim 1
8. The neutralized filtrate, according to process referred in claim 6, is allowed to settle overnight and the supernatant is filtered once again to get rid of calcium sulfate particles.
9. Continuing the process, according to step (e) of claim 1, the filtrate resuhing out of process according to claim 8, is subjected to fermenation by adding yeast (Saccharomyces cerevisiae) at a concentration of 2.5 g/L, kept atrotary incubator maintained at 125 rpm for 48 hrs.
10. Continuing the process according to step (0 of claim 1, the fermented broth, as a result of process according to claim 9, is subjected to distillation to find out the alcohol content.
11. Further, according to step (f) of claim 1, the ethanol in the distillate obtained from the fermented hydrolyzate of the biomass is estimated by titrimetric method using potassium dichromate, potassium iodide ag;ainst sodium thio-sulphate with starch as indicator and using absolute alcohol at 1.2mg/ml concentration as standard.
12. According to step (g) of claim 1, the yield of alcohol is calculated with reference to weight of input raw material and the sugar content in the hyrolyzate of the raw material according to claim 5.
13. The entire sequence of process, according to claim 1, can produce bioethanol varying from 13 to 52 %, based on the input material used, and this process can effectively be used for production of bioethanol on commercial scale.