Recovery of Ammonium Lactates from Fermentation Broth by Nanofiltration

Abstract

For the recovery of ammonium lactate by nanofiltration, TFC-SR2 membrane was selected through a permeation test with single-salt and glucose solutions. For the optimization of operating conditions under various operating pressures (50~250 psig.), the effects of lactateconcentration (0.5~2.0 M), flow rate (0.5~2.5 L/min), temperature (15~35℃), and pH (5.0~8.0) on the solution flux and lactate rejection were investigated with model solutions. The optimal lactate concentration was found to be 2.0 M, flow rate 1.5 L/min, temperature 30℃, and initial pH 7~8. For a model solution containing 1.0 M ammonium lactate at an operating pressure of 200 psig, the rejections of lactate, acetate, phosphate, sulfate and total protein were 22.7%, 6.9%, 47.7%,91.5% and 94.4%, respectively under the optimal conditions. Finally, ammonium lactate was recovered from an actual fermentation broth containing 1.5 M lactate under the optimal conditions. At an operating pressure of 200 psig, the rejections of lactate, acetate, phosphate,sulfate and total protein were 19.4%, 9.8%, 43.4%, 69.8% and 97.1%, respectively.