ETHANOL PRODUCTON

Anaerobic Fermentation of alcohol

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

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

YeastPrimary 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)

RAW MATERIALSSaccharine Starch &Cellulose materials

SACCHARINE:-Simple, directly fermentable, 6 & 12 C moleculesGlucose, 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%

MOLASSES:-Beet or cane molasses Contain 52 – 55 % fermentable sugars Molasses with above 15 – 20 % sugar cont will need to be diluteA ton yeild-70-80 gallons CANE SORGUM :-14% fermentable sugar contentExtraction requires heavy duty13-14 gallons of alcohol / tonAcidification is necessary

SUGAR BEET :-Mostly preferred 15% sugar, 82% water, small amount of starchJuice Is extracted by crushingA 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 tonBack slopping in the range of 20-25%Acidification is necessary

Sugar beet sugar corn

Starchy materials:-Materials that contain more complex carbohydratesGrains :-Grains must be milled, diluted & coked & fermentedContain large amounts of fermentable materialsAlcohol yield is dependent on converted starchJerusalem artichokes :-Abundant source of alcohol ( 16 – 18%) fermentable

materialA 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)

grains artichokes

potatoes sweet potato

PH is adjusted & fermentation is carried outPotato:-15 -18% fermentable sugar A ton yield 20-25% of alcoholCooked with steam under pressureAfter cooking mash is cooled to conversion for 15-20 minOnce converted PH should be adjusted mash is fermentedSweet potato:-27-28% fermentable sugarA ton should yield 40 gallons of alcohol Similar manner to potatoes Dilution is required (66%water)

Processing stepsStarchy materials are of 2 categories1. Encased by grain hulls 2. Starch is readily availableMalting:-Seeds are moistened & allowed to sprout These seeds are powdered & the powder is called

malt Milling:-Grains are milled to expose the starchMaterial is ground as fine as possible

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 pressureTo dissolve the water soluble starches Always done with steam under pressure at 100°cUse less water during cooking & water may be

added to dilute the mash So cooling time may be savedNew method :- Milling & cooking in one operation without use of water The cooked malt is called mash

Conversion :-Conversion of starch to fermentable sugar (Maltose)

by certain enzymes in the malt or by acid hydrolysisEnzyme extracts:-Commercially available3 basic types :1. α amylase - produce dextrose2. Β amylase - produce maltose3. Gluco amylase – reduce the remaining starch

Acid hydrolysis:-Conversion by the action of acidRequires acid proof equipment and high tempDilute mineral acid(H₂SO₄) is added to grain slurryThen immediately neutralized with calcium

hydroxide Mash cooling:-Mash is cooled after conversion & PH is checked Cooling coils are used for coolingCooling time is reduced as much as possible

FermentationBatch 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%.

Continuous fermentation not commonly usedIn US 10 large scale plants among them 4 are used

con fermentationNutrient solution was molasses with di ammonium

phosphate PH was adjusted to 5 with H₂SO₄ Fermentation temp -35°cAfter fermentation cells were separated by

centrifugation and channeled back into the first fermenter

PRODUCT RECOVERYCell 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]

Separation of cell biomassFlocculation flotation Filtration centrifugationflocculation:- Flocculating agent is added hydrocolloids inorganic salts organic poly electrolyte produce large aggregate which still settle more

readily

Flotation :-by introducing gas into liquidCells gets adsorbed to the gas bubbles & rise to the

foam layer at the top of vessel That can be collected & removed from the

bioreactorFiltration:-Bacterial cultures – absolute filters filamentous Fungi- depth filtersstatic & cross flow filtration

DistillationSeparation 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

Ethanol B.P - 78.5°C Water B.P - 100°CPurification:-By chromatography HPLC GLCApplicationssolvent in the manufacture of varnishes and

perfumesPreservative for biological specimensIn the preparation of essence and flavorings

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

ByproductDDGS (distillers dried grain with solubles)Co₂– used for the production of dry ice and preparation

of soft drinksYeast biomass- animal fodder (contains proteins &vit)