Industrial production of solvents especially ethanol

1. MICROBIAL PRODUCTION OF
SOLVENTS

2. SOLVENT
Liquid that dissolves any kind of solute.
Common solvents
* Ethanol
* Acetone
* Butyl alcohol
* Glycerol etc..

3. COMMON USES
 Dry cleaning (tetrachloroethylene)
 Paint thinner (toluene, turpentine)
 Nail polish removers & glue solvents( acetone,
ethyl acetate, methyl acetate)
 Spot removers(hexane, petrol ether)
 Detergents( citrus terpenes)
 Perfumes (ethanol) &
 Chemical synthesis..

4. Ethanol production
Petrochemical – hydration of ethylene
Biological – fermenting sugars with yeast
Chemical ethylene hydration :
 Raw materials: petrochemical feedstocks
 Process : acid- catalyzed hydration of ethylene
 Reaction : C₂H₄ + H₂O CH₃CH₂OH
 Catalyst : phosphoric acid – adsorbed onto a
porous support(diatomaceous earth/charcoal)

5. Biological fermentation :
Dry mill process or wet mill process.
DRY MILL PROCESS
Overall reaction involved
 fermentation of starch portion of corn into sugar
 distillation into alcohol

7. Steps involved in dry mill process
SACCHARIFICATION
Cooled mash + glyco amylase - Liquefied sugars to fermentable sugars (dextrose)
LIQUEFICATION
Meal + water +alpha amylase -Cookers (120 -150)˚c & 95˚C – starch is liquefied
MILLING
Feed stocks passed through Hammer mill - Fine powder ( meal)
FERMENTATION
Sugars ethanol & CO₂
Continuous flow of mash through several fermenter–fully fermented & leaves the tank
Batch process – mash in one fermentor for 48 hrs (beer) before distillation is started
yeast

9. DENATURING
Ethanol used for fuel must be denatured or made unfit for human consumption, with
a small amount of gasoline (2-5%) This is done at ethanol plant
DEHYDRATION
Alcohol from top of the column – dehydration system (remaining water removed)
Most ethanol plants use molecular sieve to capture last bit of water in the ethanol
Alcohol product at this stage (anhydrous ethanol – pure, without water) – 100% proof
DISTILLATION
Fermented mash(beer)–10% alcohol & all non-fermented solids from corn & yeast cells.
Mash – pumped into continuous flow, multi-column distillation system – alcohol
Alcohol leaves the top of final column at 96% strength & residue mash (stillage)
transferred from base of the column to the co-product processing area

11. Co- Products
Distillers grain :
used wet or dry – highly nutritious livestock feed
CO₂ :
Given off in great quantities during fermentation
Many ethanol plants collect ,compress & sell it for use in other
industries.
 Most ethanol from microbial fermentation-preparation of beverages.
 Ethanol production from sugary substrates-expensive than naturally
available petroleum.
 Microbial conversion of sugar to alcohol is limited by the toxicity of
alcohol which cannot accumulate in the fermenter beyond a limit.
 The recovery process which involves distillation requires energy input.

12. Ethanol production by bacteria
 Bacteria which can ferment sugar faster than yeast have
been found
eg. Zygomonas mobilis &
Thermophilic Thermobacter ethanolicus.
 As sugary substrates are expensive & are used for food, it
may be possible to use cellulosic materials & photosynthetic
MOs.
 Process:
1. Cellulose Sugar
2. Sugar Alcohol
Clostridium sp.
Zygomonas mobilis (or)
Thermobacter ethanolicus

13.  The anaerobic bacterium Clostridium ljungdahlii, (in
commercial chicken wastes) can produce ethanol from
single carbon sources including
* synthetic gas,
* a mixture of CO and H
that can be generated from the partial combustion of
either fossil fuels or biomass.
 If these techniques coupled with genetic engineering
techniques - possible to produce cheap ethanol to meet
the organic solvents & automative fuel requirements of the
world.

14. Advantages of Z.mobilis over S.cerevisiae
 Higher sugar uptake & ethanol uptake
 Lower biomass production
 Higher ethanol tolerance
 Doesn’t require controlled addition of oxygen during the
fermentation
 Amenability to genetic manipulations
Limitations compared to yeast
 Difficulties in converting large amount of complex CHO
polymers like cellulose, hemicelluloses and starch to ethanol.
 Its utilizable substrate range is restricted to glucose, fructose and
sucrose.
 Its resulting in by-products such as sorbitol, acetoin, glycerol
and acetic acid.
 Formations of extracellular levan polymer.

15. ACETONE & BUTYL ALCOHOL
 Chaim Weizmann, England in the early part of this
century when
acetone: production of explosives &
butanol: making synthetic rubbers.
 N-butanol is used in brake fluids, urea-formaldehyde
resins & in lacquers used as protective coatings in
automobiles.

16. Organism:
1. Clostridium acetobutylicum – 1st organism – industrial
production of acetone from starch.
2. Clostridium saccharoacetobutylicum – convert molasses
into acetone & butanol.
 submerged cultures
 Substrate: sterile diluted molasses or cooked corn meal.
 pH : 7.2
 Type of fermentation: anaerobic
 By-products : CO₂( preparation of dry ice) & H (fuel)
 Product recovery : fractional distillation

17. GLYCEROL
Main uses :
 solvent in food colouring agents
 Lubricant in toothpastes, candies, cake icings
 Cosmetic & pharmaceutical industries
 Production of explosives & propellants.
Production:
 organism : yeast - Saccharomyces cerevisiae or
bacteria – Bacillus subtilis

18. BY
R.ABARNA
BTH-12-001
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