Chromium Removal from Wastewater by Reverse Osmosis

This study describes the removal of chromium from wastewater using pressure-driven membrane separation processes. It describes the rejection of trivalent chromium using a commercial membrane for reverse osmosis typed RO98pHt (Alfa Laval, Sweden). Model solutions of chromium were used for performing of separation experiments. The effects of feed pH, chromium concentration and temperature were investigated and conductivity values of all streams were observed. The results showed that pH of the feed solution and the form of occurrence have influence on the stability of dissolved particles with possible negative impact on membrane fouling. The stability of prepared solutions was managed by the diagram of area of prevailing existence. Membrane rejected almost 100% of Cr(III) at various pH values using 100 mg.L model solution, operating pressure 1.5 MPa and at temperature 20°C. Similar results showed separation experiments using various Cr(III) concentration from 10 till 560 mg.L and pH=5±0.2. Increase of operating temperature causes higher permeate flux and has no significant influence on the rejection level of Cr(III). Obtained results show differences between various feeds separations containing the same pollutant and usage possibility of reverse osmosis for wastewater treatment. Key-Words: chromium, tanning, pollutant, membrane separation, reverse osmosis, wastewater treatment, leather industry