Bioconversion Ert 317

7/29/2019 Bioconversion Ert 317

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CHAPTER 6:

BIOCONVERSIONTECHNOLOGIES


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Course Outcome

Ability to discuss the technologies available in

bioconversion.


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Introduction: BIOCONVERSION

ABUNDANCE OF BIOMASS

WHOLE OVER THE

WORLD

Sugarcane

residue

Impose environmental

problems


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What is Biomass

Living and dead biological material that can be

used for biofuel or industrial production.

Focus on biomass produced from agriculture

activities.


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How to use the biomass?

1. Convert to useful products.

2. Convert to energy.

What method can we use?

Physically?

Chemically? Biologically?


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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


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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).


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Physical Method

Mechanical processes; pelletization of wood waste,

paddy straw.

Extraction process
http://rds.yahoo.com/_ylt=A9G_bHLfIOtH0FEAwNejzbkF/SIG=127pv8gsi/EXP=1206678111/**http%3A//www.flickr.com/photos/rmarinello/1514636725/


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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


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Biological methods use of the enzymes of bacteria and other micro-

organisms to break down biomass.

micro-organisms are used to perform the conversionprocess: anaerobic digestion, fermentation andcomposting.

The importance group of bacteria in bioconversionare:

1. Lactic acid bacteria

2. Acetic acid bacteria

3. Bacteria of alkaline fermentation
http://en.wikipedia.org/wiki/Anaerobic_digestionhttp://en.wikipedia.org/wiki/Fermentation_%28biochemistry%29http://en.wikipedia.org/wiki/Compostinghttp://en.wikipedia.org/wiki/Compostinghttp://en.wikipedia.org/wiki/Fermentation_%28biochemistry%29http://en.wikipedia.org/wiki/Anaerobic_digestion


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What is bioconversion

Bioconversion is the conversion of organicmaterials, such as plant or animal waste, into usableproducts or energy sources by biological processesor agents, such as certain microorganisms orenzymes.

Things to consider:

1. What to convert

2. what to use3. What to get


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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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Types of Bioconversion

Solid state fermentation process can be

defined as the growth of microorganisms

especially fungus on insoluble substratewith sufficient moisture but not free water.

On the contrary, in liquid state

fermentation, microorganisms are grown inliquid media with existence of water.


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Types, Advantages & Disadvantages

of Bioconversion

Factor Solid-state fermentation Liquid state fermentationSubstrates Polymer insoluble substrates: starch, cellulose, pectin,

lignin. Substrate requires pretreatment (size reduction

by grinding, chopping, homogenization etc)Soluble substrates do not require pretreatment.

Aseptic conditions Vapor treatment, non-sterile conditions Heat sterilization and aseptic controlWater Limited consumption of water, no effluent High volumes of water consumed and effluent

discardedMetabolic heating Low heat transfer capacity Easy control of temperatureAeration Easy aeration and high surface exchange air or

substrate Limitation of soluble oxygen, high level of airrequiredpH control Buffered solid substrates Easy pH controlMechanical agitation Agitation is difficult, therefore static conditions

preferred Good homogenizationScale up Need for engineering and new design equipment Industrial equipments availableInoculation Spore inoculation, batch, high inoculum volume

needed, spore have longer lag time due to the need

for germinationEasy inoculation, continuous process

Contamination Risk of contamination for low rate growth fungi Risks of contamination for single strain bacteriaEnergetic consideration Low energy consuming High energy consumingVolume of equipment Low volumes and low cost of equipments High volumes and high cost technology


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BIOCONVERSION TECHNOLOGY

FOR

ACETIC ACID PRODUCTION


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Acetic acid

CH3COOH, also known as ethanoic acid

is an organic acid that gives vinegar its sour taste andpungent 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


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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.


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Type of culture : highly aerated fermentation

Raw material : diluted purified ethanol from grapejuice, 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 onemole each of acetic acid and water;

- C2H

5OH + O

2 CH

3COOH + H

2O


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Factors influence acetic acid production

Factors influence - Oxygen supply and the concentrationgradients of ethanol and acetate.

1. Lack of oxygen

lack of O2 will killed the bacteria because they areextremely sensitive.

to overcome this problem, has to use efficient aeration

efficient aeration can be achieved with the used ofcompressed air and proper mechanical device.

for efficient aeration also have to consider shear stressimparted by the fluid and the microorganisms itself.


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the efficiency depends on the ratio between the energy inputnecessary 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.


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CITRIC ACID PRODUCTION


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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 ofcarbohydrates or citrus juices

Usage :

- to add an acidic or sour taste to foods and soft drinks.

- general additive in the confectionery industry.

- pharmaceutical industries


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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


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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.


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Factor influence citric acid production using submergedculture method.

sensitive to iron. Medium used must be iron-deficient.Fermentor must be stainless steel to prevent leaching ofiron frm fermentor wall

Oxygen supply

pH should maintain below 2.0. At higher values, A.nigeraccumulates gluconic acid rather than citrate.


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Ethanol production


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Bioconversion technology for ethanol

production Ethanol or ethyl alcohol (C2H5OH) is a clear colourless

liquid, it is biodegradable, low in toxicity and causeslittle environmental pollution if spilt.

Ethanol burns to produce carbon dioxide and water.

Ethanol is widely used in Brazil and in the UnitedStates.

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.


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Bioethanol, unlike petroleum, is a form of renewable

energy that can be produced from agriculturalfeedstocks.

It can be made from very common crops such as

sugar cane, potato, manioc and maize.
http://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/wiki/Cropshttp://en.wikipedia.org/wiki/Sugar_canehttp://en.wikipedia.org/wiki/Potatohttp://en.wikipedia.org/wiki/Maniochttp://en.wikipedia.org/wiki/Maizehttp://en.wikipedia.org/wiki/Maizehttp://en.wikipedia.org/wiki/Maniochttp://en.wikipedia.org/wiki/Potatohttp://en.wikipedia.org/wiki/Sugar_canehttp://en.wikipedia.org/wiki/Cropshttp://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/wiki/Renewable_energy


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Basic biology and technological method

- biologically, alcohol was formed when there is an action of

microorganisms in the form ofyeast 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 ofpre-treatment.

1. Sugarcontaining biomass

2. Starch containing biomass


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Bioethanol production

Substrate : Sugar containing

biomass


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27/11/2012


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Sugar containing biomass : sugar cane, molasses,sugar beet

Production steps :

1. milling/grinding (extract juices)

2. fermentation of juices (sugar)

with yeastsugar + yeast ethanol + carbon dioxide


3. Distillation

4. Dehydration


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Substrate : Starch containing

biomass


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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 (68-74C). Gelatinization is the formation ofstarch paste.


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3.Dextrinization

Dextrinization is the breakdown of gelatinized starch into smallerfragments or dextrins by means of - or -amylase. The action of-amylase on gelatinized starch results in dramatic reduction ofviscosity.

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 whereyeast is added. It is catalyzed by the action of enzymes present inmicroorganisms like yeasts with ethyl alcohol as the end product.




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6.Distillation

After fermentation, the fermented liquor is transferred to a

distillation process where the ethanol is separated from theremaining stillage (residue non-fermentable solids and water).Distillation is the process in which a liquid or vapor mixture oftwo or more substances is separated into its component fractionsof desired purity by the application or removal of heat. This

process can usually produce a 95.6% by volume ethanolproduct.

7.Dehydration

Ethanol from distillation process is sent to the molecular sieves

column for further dehydration to produce 99.7% v/v ethanol.


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Substrate : cellulose containing

biomass


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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 sugarsincluding e.g. xylose, mannose and glucose, depending on the type of biomass. Lignin is abranched polymer of aromatic compounds.


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3. Hydrolysis of cellulose with enzyme nto produce

sugar 4. Fermentation of sugar with yeast



5. Distillation

After fermentation, the fermented liquor is transferredto a distillation process where the ethanol isseparated from the remaining stillage (residue non-fermentable solids and water).


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Biodiesel production


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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, palmoil, jathropa, sunflower oil, canola) with an alcohol.

Biodiesel can be used in pure form or may be blendedwith petroleum diesel at any concentration in most

injection pump diesel engines.


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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 fromalgae, vegetable oils, animal fats or recycled restaurantgreases; it can be produced locally in most countries.

It is safe, biodegradable and reduces air pollutants, such asparticulates, carbon monoxide and hydrocarbons.

Blends of 20 percent biodiesel with 80 percent petroleum

diesel (B20) can generally be used in unmodified dieselengines.

Biodiesel can also be used in its pure form (B100), but mayrequire certain engine modifications to avoid maintenance andperformance problems.


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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-chainaliphatic alcohols (typically methanol or ethanol).
http://en.wikipedia.org/wiki/Biodieselhttp://en.wikipedia.org/wiki/Transesterificationhttp://en.wikipedia.org/wiki/Alcoholysishttp://en.wikipedia.org/wiki/Vegetable_oilshttp://en.wikipedia.org/wiki/Vegetable_oilshttp://en.wikipedia.org/wiki/Fathttp://en.wikipedia.org/wiki/Aliphatic_compoundhttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/Aliphatic_compoundhttp://en.wikipedia.org/wiki/Fathttp://en.wikipedia.org/wiki/Vegetable_oilshttp://en.wikipedia.org/wiki/Vegetable_oilshttp://en.wikipedia.org/wiki/Alcoholysishttp://en.wikipedia.org/wiki/Transesterificationhttp://en.wikipedia.org/wiki/Biodiesel


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Production steps : biodiesel from soybean seeds1. Raw materials screening

Remove impurities/dirts from raw materials

2. Oil extractionExtract 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 andGlycerol


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Transesterification


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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


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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


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Remediate ecological disaster

-Municipal solid wastes is getting out of control

necessitating bigger landfills that are further

away from our urban centers. This excess wastecontributes to land, water, and air pollution


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Convert solar energy into liquid fuels


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Reduce Greenhouse Gases

Please read article entitle Carbons New Math to get full picture on this

Advantages.


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Remediate ecological disaster

1. Municipal solid wastes

is getting out of controlnecessitating bigger landfills that are further awayfrom our urban centers. This excess waste contributesto land, water, and air pollution

2. Rural agricultural residues and damaged crops couldhave a higher value as soil amendments and biomassfeedstock

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Bioconversion Ert 317