Effect of some operating variables on citrate recovery from model solutions by electrodialysis
The effect of pH and temperature (straight theta) on the overall performance indicators (i.e., solute recovery, rho, and Faraday, eta, efficiencies; specific energy consumption, epsilon, solute, JS, and water, JW, fluxes) of batch electrodialytic recovery of citric acid from model solutions was assessed at different values of feed solute concentration (cSf) and electric current density (j). Regardless of the initial feed concentration used, rho and JS were found to be independent of straight theta; eta and JW exhibited a positive trend with respect to straight theta, while epsilon a negative one. At the maximum temperature tested (33 degrees C), as the pH of the feed solution was varied from 3 to 7, rho increased from 0.90 +/- 0.08 to 0.97 +/- 0.02, eta grew from 0.09 +/- 0.02 to 0.50 +/- 0.01, JS practically doubled, epsilon reduced about 8 times, but JW increased from 3 to 4 times. So, the optimal conditions for this technique are to be determined by balancing the savings in the investment and maintenance costs against the energy costs. Copyright John Wiley & Sons, Inc.
Desalination of glutamine fermentation broth by electrodialysis
Abstract An electrodialytic process was proposed to achieve an efficient desalination of glutamine (Gln) fermentation broth. Several electrodialytic experiments using different combinations of anion- and cation-exchange membranes were carried out, and a set of satisfactory combination of membranes was selected for the desalination. The effects of operational current density and pH on desalination and glutamine recovery were investigated and discussed. The electrical current efficiency and the energy consumption were also studied. The loss of glutamine could be reduced effectively when the current density was kept at 204 A/m2 and pH was controlled near the isoelectric point of glutamine (pI: 5.65) during the process. The clear solution after this electrodialytic desalination can meet the further simple separation of glutamine from the solution using anion-exchange resin.
Lactic acid from acid whey permeate in a membrane recycle bioreactor
Whey permeate was obtained by ultrafiltration of cottage cheese whey and supplemented with yeast extract. The lactose in the permeate was converted into lactic acid by Lactobacillus bulgaricus in a high-performance membrane bioreactor configured in the cell recycle mode. At a cell concentration of 10 g l−1, optimum productivity of lactic acid was 35 g l−1 h−1. Increasing the cell concentration to 30 g l−1 enabled the use of a dilution rate of 1 h−1 with complete substrate utilization. At 60 g l−1, productivity was over 80 g l−1 h−1 with complete substrte utilization; this is vastly superior to conventional batch fermentations.