Experimental Investigation of the Sweet Whey Concentration by Nanofiltration

The main goal of our work was to examine the possibility of using membrane separation to concentrate sweet whey, which could then be used as the basis of more products (e.g., ice cream, soft drinks containing whey).Whey from cheese making was concentrated by nanofiltration. The operating parameters were determined in permeate recirculation mode, and the concentration experiment was carried out under optimal conditions. The analytical assay of the permeate and concentrate such as total soluble solid content (TSS), protein content, and lactose content was determined using infrared measurements. The retention of lactose was over 95% up to 3.0 volume concentration ratio (VCR) at 20-bar transmembrane pressure. The analysis of the process was based on the resistance in series model and the van’t Hoff law. The model parameters were determined on the basis of lactose content, assuming that lactose is the key component of whey. The values of these parameters are the concentration polarization (β = 1.68) and total resistance (R TOT = 1.60 × 1014 m−1). The procedure was also repeated based on TSS, and the value of the total resistance was almost the same (R TOT = 1.59 × 1014 m−1). Due to this, the applied models describe appropriately the batch membrane concentration process of whey. The lactose concentration can be used for the calculation instead of TSS, which simplifies the job of estimating the model parameters.