We investigated separation of lactic acid solutions from model fermentation broth using a dynamically formed ultrafiltration membrane. The model fermentation broth was prepared from whey and Lactobacillus acidophilus bacteria. The research evaluates the influence of select lactic acid bacteria on fermentation product quality. The specific objectives of the study were to evaluate the performance of an ultrafiltration membrane consisting of zirconium oxide stainless steel (ZOSS) on lactic acid purification. We measured the effects of transmembrane pressure, cross-flow velocity, and initial bacteria concentration of the feed stream on permeate flux and lactic acid recovery. Experiments to test the lactic acid recovery were conducted at two pressure levels (1.0 and 2.0 MPa), one bacteria concentration (1 g/dm³), and three values for the cross flow velocity (0.5 m/s, 1 m/s, and 2.6 m/s). We also evaluated the influence of select lactic acid bacteria on fermentation product quality.