VERMICOMPOST AND SHEEP MANURE USED TO STABILIZE POTENTIALLY TOXIC ELEMENTS IN MINE RESIDUES

Abstract

A selection of amendments was carried out to reduce the availability of Cu, Pb, Cd and Zn from a mine residue of Zimapan, Hidalgo. Vermicompost (V) and sheep manure (E) were used as organic amendments (1=5%, 2=10% y 3=15% mass/mass) and expanded perlite as inorganic amendment (PE1=2%, PE2=5%, PE3=10% y PE4=20%). The stabilization (availability) of potentially toxic elements (PTE) was evaluated after incubation for 75 days of the mine residue with the amendments. Infrared analysis (IR) was performed to determine functional groups that were possibly involved in the stabilization of the PTE. The amendments V2, V3 and E1 stabilized the highest proportion of Pb (16%, 16% and 18%, respectively). Likewise, E1, E2 and E3 reduced Cu availability in a range from 14% to 18%. A decrease of availability in Zn was not observed with any of the amendments. In contrast, Cd was solubilized with all amendments. The IR analysis showed modification in phosphate and NH groups as well as aromatic groups linked to OH and NH from the amendments when mixed with the mine residue. These groups could interact with PTE and stabilize them. Based on the results obtained, the use of V and E is recommended. However, a longer incubation time is suggested to increase PTE stabilization.