Recovery of Cleaning Solutions from Dairy Manufacturing Effluents Using Membrane Technology

The recovery concept of cleaning solutions, based on single-phase detergents from cleaning-in-place (CIP) effluents from the dairy industry, is presented. The first step consists of ultrafiltration (UF) (with a cut-off of 5 or 10 kDa) to reduce the high load of milk proteins, followed by nanofiltration (NF) (with a cut-off of 200 Da) to separate low molecular weight lactose. Membrane steps were performed in the concentration mode, achieving a recovery of 75% of the solutions. UF modules reduced 70-85% of chemical oxygen demand (COD), 99% of milk proteins, and 45-70% of lactose, limiting the susceptibility of NF modules to fouling. Combined with nanofiltration, the efficiency of the purification system is 100% for proteins and more than 99% for lactose. The solutions recovered in the proposed purification variants are recognized as sodium hydroxide solutions with a surfactant admixture, and they can be successfully re-used for cleaning processes in the production plant.