Industrial Production of Citric Acid

Industrial Production of Citric Acid
Application of Citric Acid: (text,p.524)
- Acidulant in food, confectionary, and beverage
(75%)
- Pharmaceutical (10%), e.g. soluble aspirin
preparation
- industrial (15%): complexes with metals such as
iron and copper to be stabilizer of oil and fats.
Citric Acid Production by Aerobic Bioprocesses
Wikipedia
Industrial Production of Citric Acid
- Microorganism: Aspergillus niger (mainly), Candida
yeast (from carbohydrates or n-alkanes)
- Citric acid production is mixed growth associated, mainly
take place under nitrogen and phosphate limitation after
growth has ceased.
- Medium requirements for high production
- Carbon source: molasses or sugar solution.
- Na-ferrocyanide is added to reduce Iron (1.3 ppm) and
manganese (<0.1ppm).
- High dissolved oxygen concentration
- High sugar concentration
- pH<2
- 30 oC.
Industrial Production of Citric Acid
Bioreactor: batch or fed-batch (100m3)
- 5-25X106 A. niger spores/L may be introduced to the
fermentor.
- Aeration is provided to the fermenter by air sparging (0.1-0.4
vvm)
- Temperature is controlled by cooling coil.
- Agitation: 50-100rpm to avoid shear damage on molds.
- Fed-batch is used to reduce substrate inhibition and prolong
the production phase one or two days after growth
cessation.
- Volumetric yield: 130 kg/m3
Industrial Production of Citric Acid
Separation:
- The biomass is separated by filtration
- The liquid is transferred to recovery process:
- Separation of citric acid from the liquid: precipitation
calcium hydroxide is added to obtain calcium citrate
tetrahydrate → wash the precipitate→ dissolve it with
dilute sulfuric acid, yield citric acid and calcium
sulfate precipitate → bleach and crystallization →
anhydrous or monohydrate citric acid.
Industrial Production of Ethanol
Application of Ethanol:
- Medical
- Fuel
- Industrial
Ethanol Production by Anaerobic Bioprocesses
Glycolysis
Industrial Production of Citric Acid
- Microorganism:
S. cerevisae for hexose
Candida sp. for lactose or pentose
Genetically modified E. coli
- Ethanol production is growth-associated with S.
cerevisae.
- Medium requirements for high production
- Carbon source: sugar cane, starch materials (e.g. corn,
wheat), cellulosic materials (?!). yield: 0.51 g ethanol/g
glucose.
- N, P, minerals.
- Anaerobic
- 100g/L glucose are inhibitory for yeast.
- 5% (v/v) of ethanol are inhibitory for yeast.
- pH:4-6 for 30-35 oC.
Industrial Production of Citric Acid
Bioreactor: batch, continuous or with cell recycle
95% conversion of sugars with a residence time of
40 h in batch reactor
21 h in continuous reactor without cell recycle
1.6 h in continuous reactor with cell cycle
By-products: glycerol, acetic acid, succinic acid.
Separation:
- Distillation to obtaining 95% (w/w) of ethanol-water
mixture, followed by
- Molecular sieves to removing water from the
mixture to get anhydrous ethanol.
Ethanol Production
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