The permeate flux and chemical oxygen demand (COD) reduction were investigated in dairy process waters using a vibratory shear-enhanced filtration system (VSEP) and various nanofiltration (NF) and reverse osmosis (RO) membranes. Dairy process waters were simulated by UHT skim milk diluted 1:3 to obtain an initial COD of 36000mgO 2 l - 1 . In NF the highest permeate flux (270lh - 1 m - 2 at 4MPa, 45 o C and initial concentration) was obtained with a Filmtec membrane which yielded also the highest permeate COD (94mgO 2 l - 1 ). The best compromise was obtained with a Desal 5 DK membrane which yielded a COD of 36mgO 2 l - 1 and a flux of 240lh - 1 m - 2 under same conditions. In concentration tests, the permeate flux decreased with increasing volume reduction ratio (VRR) to reach 25lh - 1 m - 2 for the 5 DK membrane at VRR=7 while permeate COD soared to 1050mgO 2 l - 1 .A comparison with published data collected using a spiral module and same test fluid at 25 o C and 1.9MPa showed a definite advantage for the VSEP equipped with the same 5 DL membrane and operated at same pressure and temperature. The VSEP yielded a permeate COD of 24mgO 2 l - 1 versus 128mgO 2 l - 1 for the spiral module together with a higher flux 71lh - 1 m - 2 versus 24lh - 1 m - 2 . The better performance of the VSEP can be attributed to its higher membrane shear rate which reduces lactose concentration at membrane and its transmission. As expected, permeate COD was further reduced to less than 22mgO 2 l - 1 at a VRR of 5.6 by using an RO membrane.