ethanol production and product recovery from starchy materials

1. ETHANOL
PRODUCTON

2. Anaerobic Fermentation of alcohol

3.  Ethanol is used as
solvent
chemical intermediate
fuel
Solvent:-
Resins, pharmaceuticals , cosmetics ,household
cleaning products, industrial solvent
Fuel:-
Used as a bio fuel , In internal combustion engines
Chemical intermediate :-
• petroleum derived chemicals
• Butadiene production

4. Organisms for ethanol production:-
Bacteria:-
Many bacteria can produce ethanol
Many produce end products
• Other alcohol
• organic acids
• Polyols
• Ketones gasses
Many bac metabolize glucose by EMP pathway
• Clostridium sps
• Spirochaeta sps
• Sarcina sps
• Streptococcus sps

5. Yeast
Primary interest are saccharomyces sps
Organisms are selected by
• High growth and fermentation rate
• High ethanol yield
• Osmotolerance
• Low PH
• High temp
• Hardiness under physical and chemical stress
• Ethanol and glucose tolerance(allows conversion of
conc feeds to conc products)

6. RAW MATERIALS
Saccharine
Starch &
Cellulose materials

7. SACCHARINE:-
Simple, directly fermentable, 6 & 12 C molecules
Glucose, fructose, maltose
FRUITS:-
Grapes – 15%
Banana – 13.8%
Apples – 12.2%
Pineapples – 11.7%
Pears – 10%
Peaches – 7.6%
Oranges – 5.4%
Watermelon – 2.5%

8. MOLASSES:-
Beet or cane molasses
Contain 52 – 55 % fermentable
sugars
Molasses with above 15 – 20 %
sugar cont will need to be dilute
A ton yeild-70-80 gallons
CANE SORGUM :-
14% fermentable sugar content
Extraction requires heavy duty
13-14 gallons of alcohol / ton
Acidification is necessary

9. SUGAR BEET :-
Mostly preferred
15% sugar, 82% water, small amount of starch
Juice Is extracted by crushing
A ton yield 20 – 25 gallons of alcohol
Enzymes improve the alcohol yield
SUGAR CORN WASTE :-
7 – 15% sugar
Sugar is extracted as same as sorghum
8 – 18% gallons of alcohol per ton
Back slopping in the range of 20-25%
Acidification is necessary

10. Sugar beet sugar corn

11. Starchy materials:-
Materials that contain more complex carbohydrates
Grains :-
Grains must be milled, diluted & coked & fermented
Contain large amounts of fermentable materials
Alcohol yield is dependent on converted starch
Jerusalem artichokes :-
Abundant source of alcohol ( 16 – 18%) fermentable
material
A ton should yield about 25 gallons of alcohol
Material should be crushed to pulp & cooked for 2-
3 hrs, dilution is not necessary ( 79 – 80% water)

12. grains artichokes
potatoes sweet potato

13. PH is adjusted & fermentation is carried out
Potato:-
15 -18% fermentable sugar
A ton yield 20-25% of alcohol
Cooked with steam under pressure
After cooking mash is cooled to conversion for 15-20
min
Once converted PH should be adjusted mash is
fermented
Sweet potato:-
27-28% fermentable sugar
A ton should yield 40 gallons of alcohol
Similar manner to potatoes
Dilution is required (66%water)

15. Processing steps
Starchy materials are of 2 categories
1. Encased by grain hulls
2. Starch is readily available
Malting:-
Seeds are moistened & allowed to sprout
These seeds are powdered & the powder is called
malt
Milling:-
Grains are milled to expose the starch
Material is ground as fine as possible

16. But the fine flour is difficult to remove in distillation
process . Pot stills may reduce the problem
Cooking (preparation of mash):-
Starch is liquefied by boiling under pressure
To dissolve the water soluble starches
Always done with steam under pressure at 100°c
Use less water during cooking & water may be
added to dilute the mash
So cooling time may be saved
New method :- Milling & cooking in one operation
without use of water
 The cooked malt is called mash

17. Conversion :-
Conversion of starch to fermentable sugar (Maltose)
by certain enzymes in the malt or by acid hydrolysis
Enzyme extracts:-
Commercially available
3 basic types :
1. α amylase - produce dextrose
2. Β amylase - produce maltose
3. Gluco amylase – reduce the remaining starch

18. Acid hydrolysis:-
Conversion by the action of acid
Requires acid proof equipment and high temp
Dilute mineral acid(H₂SO₄) is added to grain slurry
Then immediately neutralized with calcium
hydroxide
Mash cooling:-
Mash is cooled after conversion & PH is checked
Cooling coils are used for cooling
Cooling time is reduced as much as possible

19. Fermentation
Batch fermentation is commonly employed.
Fermenter volume -- 600mᶟ.
3% inoculum(3×10⁶/ml)
With in 12 days yeast produce 10% ethanol
 when the process carried out at 35- 38°c , ph.4-4.5
max productivity was 1.9 g/h.
80%cells were removed in separator and brought
back again into fermenter.
When the high quality molasses is used, the max
yield is 95%.

20. Continuous fermentation not commonly used
In US 10 large scale plants among them 4 are used
con fermentation
Nutrient solution was molasses with di ammonium
phosphate
PH was adjusted to 5 with H₂SO₄
Fermentation temp -35°c
After fermentation cells were separated by
centrifugation and channeled back into the first
fermenter

22. PRODUCT RECOVERY
Cell biomass is separated by centrifugation or
sedimentation.
M.o desired end product – heated ( aggregate)
readily separated from broth by sedimentation.
Desired end product metabolite.
intracellular - n.a , vit ,enz, a.b (gresofulvin)
extracellular - a.a, acitic acid, citric acid, alcohol,
[ penicillin, streptomycin]

23. Separation of cell biomass
Flocculation flotation
Filtration centrifugation
flocculation:-
Flocculating agent is added
hydrocolloids
inorganic salts
organic poly electrolyte
 produce large aggregate which still settle more
readily

24. Flotation :-
by introducing gas into liquid
Cells gets adsorbed to the gas bubbles & rise to the
foam layer at the top of vessel
That can be collected & removed from the
bioreactor
Filtration:-
Bacterial cultures – absolute filters
 filamentous Fungi- depth filters
static & cross flow filtration

25. Distillation
Separation for a mixture of liquids
It relies on differences in B.P of component liquids
to be separated
The mixture to be separated is added to the
distilled pot & is heated
Low B.P will vaporize first. this vapors passes into
distilling head & then into condenser.
With in the condenser the vapor is cooled & it
liquefies.
The resulting liquid is then collected in receiving
flask

28. Ethanol B.P - 78.5°C
Water B.P - 100°C
Purification:-
By chromatography
HPLC
GLC
Applications
solvent in the manufacture of varnishes and
perfumes
Preservative for biological specimens
In the preparation of essence and flavorings

29. In many medicines and drugs.
As a disinfectant and in tinctures.
Used as a biofuel (99.2%).
Medically ethanol is soporific.
Used as antiseptic.
Fluid in many alcohol thermometer.
92.4%ethanol is used as solvent in cosmetics
pharmaceuticals and chemical industry
Byproduct
DDGS (distillers dried grain with solubles)
Co₂– used for the production of dry ice and preparation
of soft drinks
Yeast biomass- animal fodder (contains proteins &vit)