Effect of Additional Sorption Treatment by Cross-Linked Starch of Wastewater from a Surface Finishing Plant

Cross-linked starch, a nonconventional sorbent, was used for the final treatment of industrial wastewater discharges from a surface-treatment plant. Batch experiments showed that the material exhibited high sorption capacities toward metal and fluoride ions, leading to concentrations under current regulation values. In particular, 40−50% of the aluminum was removed, as well as 50−60% of the fluoride. Moreover, the treatment led to a significant decrease of boron and of the chemical oxygen demand (COD). Measurements of the germination rate of Lactuca sativa seeds, used as a phytotoxicity test, were carried out on discharged industrial waters before and after the finishing sorption treatment. The results indicated a synergistic negative effect of the inorganic pollutants on seed germination, whereas each element taken alone presented a considerably lower impact. Both the chemical abatement and toxicity mitigation of wastewater showed that sorption onto a nonconventional sorbent might constitute an interesti...