ert 211 biochemical engineering n.
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  2. Week 15: Bioconversion Technologies

  3. ABUNDANCE OF BIOMASS WHOLE OVER THE WORLD Impose environmental problems Introduction: BIOCONVERSION Sugarcane residue

  4. What is Biomass • Living and dead biological material that can be used for biofuel or industrial production. • Focus on biomass produced from agriculture activities.

  5. How to use the biomass? • Convert to useful products. • Convert to energy. What method can we use? • Physically? • Chemically? • Biologically?

  6. Energy from biomass Biofuels • Bioethanol – made from crops eg sugarcane, corn, potato, kenaf • Biodiesel – made from oils/fats using transesterification process • Biogas (methane, CO2, N2) – produce by the biological breakdown of organic matters in the absence of O2

  7. Products from bioconversion • Industrial chemicals (organic acids, acetic acids, giberellic acids, biopolymers) • Food additives (amino acids, nucleosides, vitamins, fats and oils) • Health care products (antibiotics, steroid, vaccines, monoclonal antibodies) • Industrial enzymes (amylases, proteases, diastases).

  8. Physical Method • Mechanical processes; pelletization of wood waste, paddy straw. • Extraction process

  9. Thermo chemical methods • A process where heat is the dominant mechanism to convert biomass into another chemical form • Three different classes of thermo chemical: • Combustion/burning • Gasification – convert carbonaceous materials into carbon monoxide&hydrogen (syngas) • Liquefaction

  10. Biological methods • use of the enzymes of bacteria and other micro-organisms to break down biomass. • micro-organisms are used to perform the conversion process: anaerobic digestion, fermentation and composting. • The importance group of bacteria in bioconversion are: • Lactic acid bacteria • Acetic acid bacteria • Bacteria of alkaline fermentation

  11. What is bioconversion • Bioconversion is the conversion of organic materials, such as plant or animal waste, into usable products or energy sources by biological processes or agents, such as certain microorganisms or enzymes. • Things to consider: • What to convert • what to use • What to get

  12. What bioconversion can do • Bioconversion can be carried out physically, thermochemically and biologically. • This process has been applied in the production of foodstuffs, organic chemicals and energy. • Biological methods for bioconversion has given priority with the use of microorganisms as less expensive yet effective agents. • This process is also known as fermentation.

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  15. Acetic acid • CH3COOH, also known as ethanoic acid • is an organic acid that gives vinegar its sour taste and pungent smell. • Acetic acid is one of the simplest carboxylic acids. • Usage : - in vinegar making (4%-18% acetic acid) - solvent - cellulose acetate used in photographic film

  16. Acetic acid production • Microorganism used : Acetobacter • is a genus of acetic acid bacteria • have the ability to convert ethanol to acetic acid in the presence of oxygen • They are Gram-negative, • aerobic • rod-shaped bacteria.

  17. Type of culture : highly aerated fermentation • Raw material : diluted purified ethanol from grape juice, apple juice, barley malt etc. • Acetic acid fermentation : - Acetobacter convert alcohol to acetic acid in the presence of excess oxygen. - The oxidation of one mole of ethanol yields one mole each of acetic acid and water; - C2H5OH + O2 → CH3COOH + H2O

  18. Factors influence acetic acid production • Factors influence - Oxygen supply and the concentration gradients of ethanol and acetate. 1. Lack of oxygen • lack of O2 will killed the bacteria because they are extremely sensitive. • to overcome this problem, has to use efficient aeration • efficient aeration can be achieved with the used of compressed air and proper mechanical device. • for efficient aeration also have to consider shear stress imparted by the fluid and the microorganisms itself.

  19. the efficiency depends on the ratio between the energy input necessary per unit weight of O2 transferred to the culture. • 2. Over-oxidation • when there is over-oxidation, acetic acid will convert to CO2 and H2O. • will decrease acetic acid production. • have to maintain acetic acid concentrations above 6% of the total culture. • and avoid the total depletion of ethanol.


  21. Citric acid • is a weak organic acid C6H8O7 • exists in greater than trace amounts in a variety of fruits and vegetables, most notably citrus fruits • commercial citric acid is produced by fermentation of carbohydrates or citrus juices • Usage : - to add an acidic or sour taste to foods and soft drinks. - general additive in the confectionery industry. - pharmaceutical industries

  22. Citric acid production • Microorganism used : Aspergillus niger or Candida sp. (yeast) • Culture method : submerged fermentation system and surface fermentation • Raw materials : Molasses, sugarcane syrup, sucrose

  23. Biochemistry of production (Involves few steps) • Breakdown of hexoses (sugar) to pyruvate and acetyl CoA. • The anaplerotic formation of oxaloacetate from pyruvate and CO2 • The accumulation of citrate within the tricarboxylic acid cycle - The key enzyme is pyruvate carboxylase, constitutively produced in Aspergillus species.

  24. Factor influence citric acid production using submerged culture method. • sensitive to iron. Medium used must be iron-deficient. Fermentor must be stainless steel to prevent leaching of iron frm fermentor wall • Oxygen supply • pH should maintain below 2.0. At higher values, A.niger accumulates gluconic acid rather than citrate.

  25. Ethanol production

  26. Bioconversion technology for ethanol production • Ethanol or ethyl alcohol (C2H5OH) is a clear colourless liquid, it is biodegradable, low in toxicity and causes little environmental pollution if spilt. • Ethanol burns to produce carbon dioxide and water. • Ethanol is widely used in Brazil and in the United States. • Most cars on the road today in the U.S. can run on blends of up to 10% ethanol and 90% petrol • Application of ethanol : raw material, solvent, used in fuel and in chemical, pharmaceutical & food industries.

  27. Bioethanol, unlike petroleum, is a form of renewable energy that can be produced from agricultural feedstocks. • It can be made from very common crops such as sugar cane, potato, manioc and maize.

  28. Basic biology and technological method • biologically, alcohol was formed when there is an action of microorganisms in the form of yeast anaerobs on sugar or carbon containing solution. • sugar + yeast ethanol + carbon dioxide • C6H12O6 + yeast 2C2H5OH + 2CO2 • For commercialization of ethanol production, two different types of substrates are available for fermentation. • Both substrates need different type of pre-treatment. • Sugar containing biomass • Starch containing biomass

  29. Bioethanol production Substrate : Sugar containing biomass

  30. Sugar containing biomass : sugar cane, molasses, sugar beet • Production steps : 1. milling/grinding (extract juices) 2. fermentation of juices (sugar) with yeast sugar + yeast ethanol + carbon dioxide C6H12O6 + yeast 2C2H5OH + 2CO2 3. Distillation 4. Dehydration

  31. Bioethanol production Substrate : Starch containing biomass

  32. Starch containing biomass : maize, cassava, grain, potato • Production steps : 1.Slurry preparation • The starch-containing substrate (Cassava powder) is mixed with water to form slurry. 2.Gelatinization • The slurry is then gelatinized with steam (68-74°C). Gelatinization is the formation of starch paste.

  33. 3.Dextrinization • Dextrinization is the breakdown of gelatinized starch into smaller fragments or dextrins by means of α- or Β-amylase. The action of α-amylase on gelatinized starch results in dramatic reduction of viscosity. 4.Saccharification • Saccharification is the complete conversion of dextrins into glucose (sugar) through the action of glucoamylase. 5.Fermentation • The resulting sugar is cooled and transferred to a fermentor where yeast is added. It is catalyzed by the action of enzymes present in microorganisms like yeasts with ethyl alcohol as the end product. • sugar + yeast ethanol + carbon dioxide • C6H12O6 + yeast 2C2H5OH + 2CO2

  34. 6.Distillation • After fermentation, the fermented liquor is transferred to a distillation process where the ethanol is separated from the remaining stillage (residue non-fermentable solids and water). Distillation is the process in which a liquid or vapor mixture of two or more substances is separated into its component fractions of desired purity by the application or removal of heat. This process can usually produce a 95.6% by volume ethanol product. 7.Dehydration • Ethanol from distillation process is sent to the molecular sieves column for further dehydration to produce 99.7% v/v ethanol.

  35. Bioethanol production Substrate : cellulose containing biomass

  36. cellulose containing biomass : paddy straw, wood, coconut husk, paper waste • Production steps : 1. biomass harvested 2. biomass pretreatment with heat or chemicals (NaOH, HCL) - Cellulose is a polymer of glucose. Hemicellulose is a copolymer of different C5 and C6 sugars including e.g. xylose, mannose and glucose, depending on the type of biomass. Lignin is a branched polymer of aromatic compounds.

  37. 3. Hydrolysis of cellulose with enzyme nto produce sugar • 4. Fermentation of sugar with yeast sugar + yeast ethanol + carbon dioxide C6H12O6 + yeast 2C2H5OH + 2CO2 • 5. Distillation After fermentation, the fermented liquor is transferred to a distillation process where the ethanol is separated from the remaining stillage (residue non-fermentable solids and water).

  38. Biodiesel production

  39. Biodiesel • Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl (methyl, propyl or ethyl) esters. • Biodiesel is typically made by chemically reacting lipids (e.g., vegetable oil, animal fat, soybean, palm oil, jathropa, sunflower oil, canola) with an alcohol. • Biodiesel can be used in pure form or may be blended with petroleum diesel at any concentration in most injection pump diesel engines.

  40. Biodiesel is a light to dark yellow liquid. • It is practically immiscible with water, has a high boiling point and low vapor pressure. • Biodiesel is a renewable fuel that can be manufactured from algae, vegetable oils, animal fats or recycled restaurant greases; it can be produced locally in most countries. • It is safe, biodegradable and reduces air pollutants, such as particulates, carbon monoxide and hydrocarbons. • Blends of 20 percent biodiesel with 80 percent petroleum diesel (B20) can generally be used in unmodified diesel engines. • Biodiesel can also be used in its pure form (B100), but may require certain engine modifications to avoid maintenance and performance problems.

  41. Biodiesel production • Biodiesel production is the act of producing the biodiesel, through either transesterification or alcoholysis. The process involves reacting vegetable oils or animal fats catalytically with a short-chain aliphatic alcohols (typically methanol or ethanol).

  42. Production steps : biodiesel from soybean seeds 1. Raw materials screening Remove impurities/dirts from raw materials 2. Oil extraction Extract oil by pressing or using solvent extraction 3. Purification Remove impurities from the oil (centrifuge) 4. transesterification Reaction of oil with methanol+catalyst (NaOH, HCl, lipase)+heat. Will produce methyl ester and Glycerol

  43. Transesterification

  44. 5. Purification a) Separation of methyl ester with glycerine. Glycerine more dense than methyl ester. So glycerine will settle at the bottom. b)Wash biodiesel with water to remove contaminants. Water is heavier than biodiesel and absorb excess methanol+NaOH