Bio eathnolo Production for environmental biotechnology

BT

1. Prof. (Dr). Hardik Pathak Jaipur

2. Bioethanol refers to the alcohol produced by the fermentation of starch and lignocellulosic substrates via microorganisms, releasing recyclable carbon dioxide, water and heat . The carbon dioxide released by the combustion of bioethanol can recycle in microalgae production as a carbon source. The generation of bioethanol typically includes four stages of operation: Pretreatment  of cellulose substrate to produce Hemicellulose or lignin. Hydrolysis  of cellulose to obtain fermentable sugars. Fermentation  of sugar into ethanol by the biomass. Distillation  and purification of ethanol.

3. Generations of Bioethanol There are four generations of bioethanol that uses different feedstocks . First-generation bioethanol : It makes the use of kernels and  starchy crops  biomass like sugar-beet, sugar-cane, wheat, corn etc. The production process requires more land area for the cultivation of crops, due to which the capital cost in the first generation is quite higher. Second-generation bioethanol : It makes the use of  lignocellulosic biomass  like wood, straw, grass and wastes etc. The production process does not require much capital cost for the maintenance and operation of sophisticated equipment. Third generation bioethanol : It makes the use of  algal biomass  whose cultivation is easy (can be cultivated on marginal land). Bioethanol derived through the cultivation of algal biomass needs low capital and has high energy density and conversion energy. Fourth-generation bioethanol : It makes the use of industrial waste  carbon dioxide . The bioethanol produced by this process is considered a carbon-negative biofuel .

4. Generations of Bioethanol

5. Bioethanol Production The production process of bioethanol can be generalized into the following five stages: Sample preparation Bioethanol can be produced by using different substrates like simple sugar (cane sugar), starch (corn) and lignocellulosic (wheat straw) biomass. For the sample preparation, it is essential to prevent  pre-fermentation  and  bacterial contamination  once the feedstock is delivered to the ethanol plant. The raw materials must include washing, cutting and drying stages for up to three days. Pretreatment Sources containing simple sugars and starch does not require pretreatment as the microorganisms or their enzymes can quickly process these during the fermentation process. But the feedstock having lignocellulosic content requires a pretreatment to separate  cellulose  from lignin and hemicellulose . lignocellulosic sources are suspended in 75%  anhydrous peroxide , to which  NaOH  is added to adjust the pH to 11.5. The mixture is then  incubated  at 35 degrees Celsius and then  centrifuged  at 250 rpm for 24 hours. concentrated  HCl  is added to adjust the pH to 4.8 before hydrolysis. Filtration is not required after the pretreatment. The liquid phase with solubilized hemicellulose and solid phase with the cellulose of the sample is subjected to enzymatic hydrolysis.

6. Process of Bioethanol Produc tion

7. Enzyme Hydrolysis The degradation of starch content like corn, wheat etc., involves the association of amylase enzyme. In contrast, degradation of cellulosic material like wheat straw, grasses etc., consists of the association of cellulase enzyme. In 10 grams of dried sugarcane, 200 ml of distilled water is added. Then add the above solution into a solution containing 0.5 ml of NaOH at a pH of 4.5. After that, 0.2 µl of enzyme α-amylase is diluted with the phosphate buffer, and the temperature is maintained at 50 degrees Celsius. The mixture is then cooled to 32 degrees Celsius. The hydrolysis of starch requires alpha-amylase and glucoamylase under high-temperature conditions. Second stage hydrolysis, the cellulose biomass into glucose by concentrated or dilute acid or  cellulase  enzyme.

8. Different Feedstock for Bioethanol Production

9. Fermentation It is a biological process that mediates the conversion of simple sugars into ethanol via the association of microorganisms like yeasts, bacteria etc. Saccharomyces cerevisiae and Escherichia coli are the most common organisms that are being used in the fermentation stage. S. cerevisiae can ferment the simple sugar into ethanol and carbon dioxide at a temperature of 37 degrees Celsius at a pH ranging from 3-5. But in the case of starch and cellulose, the fermentation process can carry out in two possible ways. The enzyme hydrolysis and the fermentation can occur separately and simultaneously by a method known as separate hydrolysis and fermentation ( SHF ) and simultaneous saccharification and fermentation ( SSF ). The SSF process yields much ethanol with reduced formation of inhibitory end products comparative to the SHF method.

10. Distillation After fermentation, the  recovery  of ethanol from the whole suspension or fermentation broth refers to the process of distillation. This stage filters out the fermentation broth to extract bioethanol from the remaining residue through Whatsmann filter paper. Then  boil  the liquid mixture of water and ethanol. As the water has a high boiling pressure ( 100 degrees Celsius ) than the ethanol having 78.3 degrees Celsius, so the ethanol will get separated from the solution mixture as vapours via the  rotary evaporator . During this process, all the co-products and impurities or residues, enzymes, ash etc., settle down at the bottom of the distillation column.

11. Advantages Bioethanol has a high octane number It has a low boiling point. It also comprises a high heat of vaporization. Water discharged from the bioethanol production plant is environmentally neutral that does not harm the ecology. It improves energy safety and the operation of transport facilities. Applications Used in petrol engines as an alternative for gasoline. It is suitable for residential use as it does not require a chimney. It is fuel for power generation and cogeneration systems. Bioethanol is also used as a feedstock in the chemical industry.

12. Thank You