Application of membrane filtration methods in cheese whey processing

Whey is an important by-product of milk technology. The byproduct of cheese-producing industries, cheese whey, is considered as an environmental pollutant due to its high biological oxygen demand (BOD) and chemical oxygen demand (COD) values. The high organic load of whey arises from the presence of residual milk nutrients. As demand for milk-derived products is increasing, it leads to increased production of whey, which has a serious waste management problem. To overcome this problem, various technological approaches have been employed to convert cheese whey into value-added products. Using membrane technology to whey processing, it became possible to demineralize, concentrate, and fractionate cheese whey in an efficient way and thus convert the waste by-product into highly valuable products. In this study, the potential of an integrated membrane process based on ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) was investigated for fractionation of cheese whey components and in addition to electrodialysis (ED) study, it is aimed to support future studies. Experimental studies were performed using a laboratory scale membrane test system (SEPA CF II GE-Osmonics). The pH, temperature, salinity, conductivity, and total dissolved solids (TDS) of the concentrate and permeate samples were measured by Hach Lange-HQD multi-meter. The protein contents of the samples were determined by Kjeldahl-N measurement and the lactose concentration with HPLC method. According to the results obtained, when the permeate of the UF membrane was passed through the NF-90 membrane, the conductivity, total dissolved solids (TDS) and salinity removal reached up to 90%, while the NF-270 membrane was removed at 40%. In the integrated UF-NF-90 and UF-NF-270 studies, the enrichment rate of protein was 26-28%, protein rejections were 69-74%, respectively, while the enrichment rate of lactose was 28% and 11%, lactose rejections were 99% and 97% respectively. Lastly, when the NF-270 concentrate composition was treated with the BW30-RO membrane, the enrichment rate of lactose reached up to 19-20% from 11% and lactose rejection was reached up to 99%. This shows us that the integrated membrane processes are more effective than the single membrane process in separating the fractions of the whey. Key words: cheese whey, integrated membrane process, utrafiltration, nanofiltration, reverse osmosis.