Paper Title
Bioremediation of Soil with High Heavy Metal Concentration, at Laboratory Scale, Using Native Microorganisms from Mining Waste in Colquijirca, Peru

Abstract
This study aims to evaluate the bioremediation potential of indigenous microorganisms from areas impacted by mining. Following this approach, two soil samples were extracted from mining sites in Colquijirca, Pasco. Subsequently, 1 kg of each sample was sent to the CEIMIC S.A.C laboratory for mass spectrophotometry analysis to determine the initial concentration of all heavy metals present in the samples. Prior to the isolation of native soil microorganisms, a preenrichment was conducted to ensure the presence of Bacillus, Pseudomonas, and fungi. Two strains with potential growth were identified: strain CP-11 (extracted from a culture medium for Bacillus sp.) and CP-08 (extracted from a culture medium for Pseudomonas sp.), which were isolated and cryo-preserved. Then, using bioaugmentation technique, biomass broths were prepared for each strain. For the laboratory-scale bioremediation stage, two soil systems were prepared with the collected samples to simulate the piles of mining waste material. Soil system 1 and soil system 2 were treated with the bioaugmented solutions of Bacillus sp. and Pseudomonas sp., respectively. The treatment lasted for one month with constant mechanical ventilation. Finally, a mass spectrophotometry analysis was conducted for each post-treatment sample, determining that the removal efficiency of CP-11 in sample 1 for heavy metals (As, Cu, Pb, Hg, Cr, and Cd) was 8.2%, 29.6%, 56.8%, 57.2%, 20.8%, respectively. Similarly, the elimination efficiency of CP-08 in M2 for the same metals was 12.2%, 22.7%, 52.8%, 13.2%, 76.6%, and 36.3%, respectively. Keywords - Bioremediation, native microorganisms, mining-affected soils, heavy metals, bioaugmentation, removal efficiency, mass spectrophotometry.