Removal of Cd and Zn from a mining company aqueous stream using artificial wetlands.

Metals from different industrial processes present in effluents can contaminate the environment causing damage such as the death of flora and fauna, and/or diseases in humans. Currently, several researches have focused on finding an efficient treatment for this type of pollutants, however, the problem remains unsolved. Among the options studied are artificial wetlands, which have proven to be efficient in the removal of metals and other pollutants present in wastewater from various industries. Therefore, this research focused on testing the removal efficiency of Cd and Zn contained in wastewater from a mining industry, using laboratory-scale systems that simulate an artificial wetland. Eight PVC reactors packed with volcanic slag (tezontle) were used. Aquatic plants or hydrophytes (Typha latifolia) were adapted to the laboratory conditions and the analytical follow-up of the metal removal process was carried out, quantifying the concentrations of cadmium and zinc in the effluents, as well as measuring pH and soluble COD. The results obtained show removal values in the order of 90% in the systems with plants and 40% in the systems without plants, for both metals. In addition, it was found that this plant species can withstand the acidic conditions, characteristic of this type of wastewater, and it was proved that it is a species that accumulates metals, since the concentrations of metals accumulated in the aerial part were higher compared to those found in the root zone.