Electrodialysis of acetic acid fermentation broths
Chukwu, Uchenna Nkechi
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Permalink
https://hdl.handle.net/2142/22814
Description
Title
Electrodialysis of acetic acid fermentation broths
Author(s)
Chukwu, Uchenna Nkechi
Issue Date
1995
Doctoral Committee Chair(s)
Cheryan, Munir
Department of Study
Food Science and Human Nutrition
Discipline
Food Science and Human Nutrition
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Food Science and Technology
Language
eng
Abstract
Electrodialysis (ED) was studied as a method to recover and purify acetate from model solutions and fermentation broths such as vinegar and calcium magnesium acetate (CMA). An initial evaluation of the ED stack with model sodium chloride solutions revealed that increasing the flow rate increased the limiting current density. There appeared to be no limiting current density for model acetate solutions.
Increasing the initial feed concentration from 58 to 314 gL$\sp{-1}$ at pH 2.4 increased the acetate flux (from 541 to 920 grams per square meter per hour, GMH) but decreased the water flux (from 2.6 to 1.3 liters per square meter per hour, LMH) and energy consumption (from 1.2 to 0.7 kWh/kg acetate transported). Increasing the current from 43 to 174 A.m$\sp{-2}$ at pH 5.6 increased the energy consumption (0.2 to 0.4 kWh/kg), acetate (107.3 to 504.1 GMH) and water flux (1.0 to 3.0 LMH). When processing feed streams at a higher initial pH, the acetate flux is lower than the low pH feed streams, perhaps due to the lower mobility of Na$\sp{+}$, Ca$\sp{++}$ and Mg$\sp{++}$ ions with respect to H$\sp{+}$ ions.
When the objective was to maximize the concentration, excellent results were obtained with multiple-stage ED. For the low pH feeds (vinegar broth), initial feed concentration increased from 91 gL$\sp{-1}$ to 300 gL$\sp{-1}$ acetic acid with an 88% volume reduction. The cells in the vinegar broth appeared to have no effect on ED parameters. For the high pH experiment (clarified CMA broth at 50 gL$\sp{-1}$ acetic acid), a maximum concentration of 144 gL$\sp{-1}$ was reached in the third stage of the experiment with an 80% volume reduction.
A preliminary economic analysis showed that ED concentration of vinegar by three-fold to 300 gL$\sp{-1}$ costs $0.1165/gallon of single-strength (100 grain) vinegar and is justified if transportation exceeds 240 miles. For acetate broths at high pH, ED costs \$165/ton acetate and is warranted if a clarified, non-colored product is required.
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