Recovery of Organic Acids From
Fermentation Broths
Southern Bio-Products Conference
March 4-6, 2004
Beau Rivage Resort
Biloxi, MS
Tim Eggeman, Ph.D., P.E.
Dan Verser, Ph.D.
ZeaChem Inc.
Organic Acids - Today
Organic Acid
Price, $/lb
(100% Basis)
US Demand,
MM lb/yr
Common
Route
Formic
0.46
50
Synthetic
Acetic
0.42
5,286
Synthetic
Oxalic
0.38
17
Synthetic
Propionic
0.49
202
Synthetic
Lactic
0.80
176
Fermentation
Tartaric
3.00
7
Fermentation
Succinic
1.00
3
Synthetic
Maleic
0.42
478
Synthetic
Adipic
0.70
1,725
Synthetic
Citric
0.75
600
Fermentation
Points of View
• Sugars:
– Inexpensive
– Under-Utilized
– More Sustainable
• Synthetic Routes will Eventually be Displaced
• Platform Viewpoint is Under-Utilized
Biology plus = Better Technology and
Chemistry
Market Diversification
Generic Platform
O
O
O
RCR
RCOH
RCOR
Ketone
Organic
Acid
Ester
O
RCH
RCH2OH
R CH2
Aldehyde
Alcohol
Olefin
C2 Platform
O
O
O
CH3CCH3
CH3COH
CH3COCH2CH3
Acetone
Acetic
Acid
Ethyl
Acetate
O
CH3CH
Acetaldehdye
CH3CH2OH
Ethanol
CH2
CH2
Ethylene
Issues in Recovery
• pH of Broth
– Unreactive Species at Near Neutral pH
– Commodity Scale Production is Constrained by
Need to Avoid Salt Coproduction
• Dilute Broths
– Evaporating Water is Expensive
– Prefer Selective Methods for Removing
Organic Acids from Water
Effect of pH
O
O
CH3COH
CH3CO-
Protonated
Acid
Dissociated
Acid
+
H+
100
90
% Dissociation
80
pKa = 4.75
70
60
Protonated Acid
50
Dissociated Acid
40
30
20
10
0
0
1
2
3
4
5
6
7
8
9
pH
Acidic
Basic
Neutral
10
11
12
13
14
pH Options
• Low pH Fermentation
• Neutral pH Fermentation
– Direct Acidification
– Amine Complex Formation
– Other
• Bipolar Electrodialysis
• Esterases
Lactic Acid - Traditional
Alcohol
Water
Lime
Sulfuric
Acid
Ester
Hydrolysis
Lactic
Acid
Sugars
Fermentation
Direct
Acidification
Gypsum
Esterification
Water
Direct Acidification
Fermentation:
Ca(Lac) 2  H 2SO4
C 6 H 12 O 6  Ca(OH) 2  H 2SO 4
Re-acidification:
Overall:
C6 H 12 O 6  Ca(OH) 2  Ca(Lac) 2  2 H 2 O
 2 HLac  CaSO 4
 2 HLac  CaSO 4  2 H 2 O
US Demand for Lactic Acid = 176 MM lb/yr,
Gypsum Coproduct = 252 MM lb/yr !!!
Lactic Acid – Amine Extraction
(From: Baniel, A.M. et. al., US Pat. 5,510,526)
Citric Acid – Lime/Acid
Lime
Sugars
Fermentation
Precipitation
Residue
Sulfuric
Acid
Water
Acidification
Crystallization
Calcium
Citrate
Gypsum
Citric
Acid
Citric Acid – Amine Extraction
Water
Fermentation
Residue
Back Extraction
Sugars
Forward Extraction
Water
Crystallization
Citric
Acid
Formic Acid
Water
CO
Carbonylation
Methanol
Methyl Formate
Formic
Acid
Hydrolysis
Methanol
O
Carbonylation:
CO
+
CH3OH
O
Hydrolysis:
HCOCH3
O
HCOCH3 +
H2O
HCOH
O
Net:
CO
+
H2O
HCOH
Some Common Themes
• Eliminating Salt Coproduction is Difficult
– Microbiology
– Careful Selection of Cations and Recovery
Scheme
• Common Purification Methods
– Amine Extraction
– Esterification
Routes to Ethanol
ZeaChem Indirect Route
Fermentation:
Dextrose
Esterification:
3 Acetic Acid + 3 Ethanol
Hydrogenation:
Net:
3 Ethyl Acetate + 6 H2
Dextrose + 6 H2
3 Acetic Acid
3 Ethyl Acetate + 3 H2O
6 Ethanol
3 Ethanol + 3 H2O
Direct Fermentation
Dextrose
2 Ethanol + 2 CO2
Lab Status - Fermentation
• Lab Scale Fermentation
– Strain: Moorella Thermoacetica ATCC 39073
– Media: Glucose+Corn Steep Liquor
• Batch Results
– First Run: 28 g/l acetate
– Goal: 35-50 g/l acetate, yield = 85+% of theoretical
Lab Status - Recovery
• Lab Scale
– Amine Complex Formation
w/ CaCO3 Precipitation
– Extraction of Amine
Complex
– Esterification
• Results to Date
– 97+% CaCO3 Recovery
– Excellent Extraction
(KD > 2)
– Ester Yield: 75% of
Theoretical
Conclusions
• Technical Issues
– pH and Avoidance of Salt Coproduction
– Dilute Broths
• Advantages of Platform Viewpoint
– New Routes Based on Biology and Chemistry
– Market Diversification
Acknowledgements
• US Department of Energy - Inventions and
Innovation Program (Grant Number DEFG36-03GO13010)
• Support by US DOE Does Not Constitute
an Endorsement by US DOE of the Views
Expressed in this Presentation