After extensive market research, the CERTH colleagues selected three commercial hollow fiber nanofiltration membranes (HF NF) based on the manufacturers' data sheets and the treatment objectives defined in the CORNERSTONE project (maximum calcium and magnesium retention, minimum retention of monovalent ions, high water flux, minimum fouling tendency). A series of tests were then carried out to evaluate the treatment of the HKM steelworks wastewater with one of the three HF-NF modules. A lab-scale NF cross-flow pilot unit (designed and built at CERTH) was used for process monitoring and optimization using the STREAMETRIC platform (AI flow predictions performing various boundary analyzes) after being upgraded with a PLC, recording and control instruments, and a remote terminal unit (STREAM-M) provided by i2M GmbH. Tests under different cross-flow velocities showed an insignificant impact on the permeate flux, while the quite stable transmembrane pressure (TMP) values indicate low membrane fouling. A water recovery of 72.5% was achieved, followed by a high rejection of divalent cations (>80% for Ca2+ and >95% for Mg2+) and a low rejection of monovalent ions (<5% for Na+ and Cl-, 12% for K+).
Centre for Research and Technology – Hellas (CERTH), January 2025
