Abstract
Tannery effluents contain high chromium concentrations, posing a significant environmental and public health risk. Most electrodialysis studies for chromium removal have used synthetic solutions; therefore, this study investigates total chromium removal from actual tannery effluents using an electrodialysis system with titanium electrodes and an MA-MK-MA membrane configuration. Preliminary tests with a synthetic basic chromium sulfate solution (1,521 mg/L) at three voltages (12.2 V, 15 V, and 9 V) yielded reductions of 66.42%, 44.06%, and 32.21%, respectively. The progressive current decrease between tests, attributed to membrane fouling, prompted a cleaning procedure by recirculating 0.05 M HCl for 20 minutes, which restored system efficiency. The actual effluent (2,363 mg/L), due to its high suspended solids content, underwent preliminary coagulation-flocculation, reducing chromium to 1,301 mg/L. The final test at 15 V for 5 hours achieved 99.79% reduction, yielding a final effluent of 2.64 mg/L total chromium. The results demonstrate that electrodialysis is an efficient alternative for treating actual tannery effluents, and that HCl cleaning effectively restores system performance.
