Membrane-based process for the recovery of lactic acid by fermen

Details Membrane-based process for the recovery of lactic acid by fermen Membrane-based process for the recovery of lactic acid by fermen

1993-10-04

1996-04-02

Spear, Frank

Liquid purification or separation

Processes

Liquid/liquid solvent or colloidal extraction or diffusing...

210651, 210259, B01D 6158

Patent

active

055037500

ABSTRACT:
A substantially continuous membrane separation process has been discovered in which the known benefits of a cell-recycle fermentor are unexpectedly enhanced because pH is controlled from 4.0 to 5.5 with a nitrogen-containing base. The ammonium lactate formed is not precipitated, allowing continuous removal of lactic acid so as to maintain a concentration of lactic acid about 12% by wt in the broth. When combined with recycle of UF retentate, operating this cell-recycle fermentor allows the build-up of a cell population in the range from above 5.times.10.sup.9 CFU/ml to 5.times.10.sup.10 CFU/ml, which population is much denser than one which can be produced with the specified pH control in a batch fermentor, after self-termination of the fermentation. This super-dense population of cells, In turn, not only accelerates production of lactic acid but also minimizes contamination by foreign cells. UF retentate is recycled to produce a specified high fluid velocity when the effluent stream is flowed over UF membranes used in the UF modules. The high fluid velocity at relatively low pressure produces a scrubbing action over the membrane surfaces which are therefore not fouled over long periods of operation. In a batch fermentation with pH control, when the fermentation is self-terminated the total lactic acid present is about 10% by wt (measured by HPLC), though free lactic acid is always <4%, and the live cell population is lower than 5.times.10.sup.9 CFU/ml because many cells die as pH drops.

REFERENCES:
patent: 3472765 (1969-10-01), Budd et al.
patent: 4444881 (1984-04-01), Urbas
patent: 4771001 (1988-09-01), Bailey et al.
patent: 5068419 (1991-11-01), Kulprathipanja
patent: 5250182 (1993-10-01), Bento et al.
"Adsorptive Purification of Carboxylic Acids" by Elizabeth E. Ernst and Donald W. McQuigg Paper #5ae at the AIChE 1992 national meeting, Separation Division preprints.
"Production of Lactic Acid from Lignocellulosic Biomass" by N. Padukone, S. Schmidt et al. Abstract only.
"Recovery of Lactic Acid by Adsorption: Resin Evaluation" by R. L. Evangelista and Z. L. Nikolov--Abstract only.

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