ERT 211 BIOCHEMICAL ENGINEERING

Week 15: Bioconversion Technologies

Introduction: BIOCONVERSION

ABUNDANCE OF BIOMASS WHOLE OVER THE

WORLD

Sugarcane residue

Impose environmental problems

What is Biomass

Living and dead biological material that can be used for biofuel or industrial production.

Focus on biomass produced from agriculture activities.

How to use the biomass?

1. Convert to useful products.

2. Convert to energy.

What method can we use? Physically? Chemically? Biologically?

Energy from biomassBiofuels 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

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).

Physical Method

Mechanical processes; pelletization of wood waste, paddy straw.

Extraction process

Thermo chemical methods

A process where heat is the dominant mechanism to convert biomass into another chemical form

Three different classes of thermo chemical:

1. Combustion/burning

2. Gasification – convert carbonaceous materials into carbon monoxide&hydrogen (syngas)

3. Liquefaction

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:

1. Lactic acid bacteria

2. Acetic acid bacteria

3. Bacteria of alkaline fermentation

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:1. What to convert2. what to use3. What to get

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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BIOCONVERSION TECHNOLOGY

FOR

ACETIC ACID PRODUCTION

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

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.

Acetic acid production

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

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.

the efficiency depends on the ratio between the energy input necessary per unit weight of O2 transferred to the culture.

2. Over-oxidationwhen 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.

CITRIC ACID PRODUCTION

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

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

Biochemistry of production (Involves few steps)

a. Breakdown of hexoses (sugar) to pyruvate and acetyl CoA.

b. The anaplerotic formation of oxaloacetate from pyruvate and CO2

c. The accumulation of citrate within the tricarboxylic acid cycle

- The key enzyme is pyruvate carboxylase, constitutively produced in Aspergillus species.

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.

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.

Bioconversion technology for ethanol production

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.

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.

1. Sugar containing biomass2. Starch containing biomass

Bioethanol production

Substrate : Sugar containing biomass

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. Distillation4. Dehydration

Bioethanol production

Substrate : Starch containing biomass

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.

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 dioxideC6H12O6 + yeast 2C2H5OH + 2CO2

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.

Bioethanol production

Substrate : cellulose containing biomass

cellulose containing biomass : paddy straw, wood, coconut husk, paper waste

Production steps :1. biomass harvested2. 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.

3. Hydrolysis of cellulose with enzyme nto produce sugar

4. Fermentation of sugar with yeast

sugar + yeast ethanol + carbon dioxideC6H12O6 + 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).

Biodiesel production

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.

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.

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).

Production steps : biodiesel from soybean seeds1. Raw materials screeningRemove impurities/dirts from raw materials2. Oil extractionExtract oil by pressing or using solvent extraction3. PurificationRemove impurities from the oil (centrifuge)4. transesterificationReaction of oil with methanol+catalyst (NaOH, HCl,lipase)+heat. Will produce methyl ester and Glycerol

Transesterification

5. Purificationa) Separation of methyl ester with glycerine.Glycerine more dense than methyl ester. Soglycerine will settle at the bottom.

b)Wash biodiesel with water to remove contaminants.Water is heavier than biodiesel and absorb excessmethanol+NaOH

Advantages of bioconversion

Increase recycling-generate money from waste

Generation of renewable energy-bioethanol..biodiesel..biogas-not too dependent on fossil fuel

Reduce landfill effect- It saves space in landfills.

Offset to fossil fuel usage-expand energy freedom of choice.

Reduce carbon emission-reduce greenhouse gasses by using bioenergy

Remediate ecological disaster

-Municipal solid wastes – is getting out of control necessitating bigger landfills that are further away from our urban centers. This excess waste contributes to land, water, and air pollution

Convert solar energy into liquid fuels

Reduce Greenhouse Gases

Please read article entitle “Carbon’s New Math” to get full picture on thisAdvantages.

Remediate ecological disaster

1. Municipal solid wastes – is getting out of control necessitating bigger landfills that are further away from our urban centers. This excess waste contributes to land, water, and air pollution

2. Rural agricultural residues and damaged crops could have a higher value as soil amendments and biomass feedstock