Reverse osmotic purification of permeates obtained by nanofiltration of dairy raw materials

Permeate of nanofiltration of dairy raw materials (NFP) in modern industry is not considered as a waste from which it is advisable to extract valuable components. Its use, for example, for washing equipment or restoring dry products is problematic due to the high residual content of dry substances. Due to these circumstances, the NFP has not yet had practical significance and has not been described in detail in the scientific literature. The composition and properties of NFP obtained on industrial equipment have been studied. Its main components are lactose and typical mineral vemilk, with the exception of calcium and magnesium, the content of which did not exceed 10 mg / kg. NFP purification was carried out by filtration through a reverse osmotic membrane. Water samples obtained after NFP purification at pressure were studied 20–55 bar and different concentration factors. The specific electrical conductivity of water varied in the range of 34–273 microns / cm depending on the pressure and degree of concentration. Calculation of the cost of reverse osmotic purification of NFP, taking into account the consumption of electricity, service and detergents, amortization of equipment and membrane elements showed that, at cost, the water obtained from the NFP is comparable to the reverse osmotic obtained by filtration of mains water, with the volumes of processing of the NFP more than 200 m3 / day.