Volatile fatty acids recovery by electrodialysis from a simulated anaerobic fermentation broth

Abstract

It was designed and built an electrodialysis unit to study the recovery like acetic acid of the acetate taken place during the anaerobic digestion of organic waste experimentally, using watery solutions of acetate of sodium to different concentrations (5 g/l, 15 g/l and 30 g/l) to simulate the liquor of anaerobic fermentation. The electrodialysis was carried out applying 8 different voltages periodically to the unit and monitoring the behavior of the main variables of the process. The maximum rate of achieved production of acetic acid was of 1674 mg/l and it was found that this went proportional to the applied voltage, flow of liquor of fermentation fed to the unit and the density of used current. The acetic acid was recovered in distilled water and additionally in a watery solution of Ethanol and it was rehearsed with success the estherification of this last mixture, being able to produce ethyl Acetate. The electrodialysis turned out to be a technically competitive alternative in principle, for the production of volatile fatty acids; because the obtained results demonstrate that it is possible to make it with relative easiness.