Examinando por Autor "Velastegui, Edgar"

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    Ítem
    Investigation of the key factors favouring the biocementing effect of microbially induced calcite precipitation when applied to mine tailings
    (Elsevier, 2025) Zuñiga Barra, Hector; Velastegui, Edgar; Toledo-Alarcón, Javiera; Jorquera, Lorena; Rivas, Mariella; Jeison, David
    Recent research has suggested the applicability of microbially induced calcite precipitation (MICP) to improve wind erosion resistance across diverse media, from clay to sandy soils. While various factors influencing MICP performance have been investigated, comprehensive studies considering the synergistic interactions between biocementation media composition, dosages, available urease activity, and urea-calcium ratios are limited. Consequently, identifying key factors governing MICP during tailings biocementation remains crucial for optimizing treatment strategies. This is specially the case for MICP application for mine tailings biocementation, due to the limited available research dealing with this substrate. This research studied the effect of several factors, when biocementing mine tailings, using a factorial design. The results confirm the key role of the biocementation media dosage and the urea-calcium ratio, and their synergistic interaction during biocementation of tailings, as they determine the calcium and inorganic carbon available to produce calcium precipitates. Biocementation of tailings by applying MICP substantially improved surface strength, leading to a drastic reduction in wind erosion resistance. These results confirm the potential of MICP to become an interesting tool to reduce windblown dust emissions from tailings deposits.
  • Miniatura
    Ítem
    Sustainable biocementation of mine tailings: Reduction of urea requirements through bicarbonate-based MICP
    (Elsevier, 2025) Zuñiga Barra, Hector; Pardo-Vasquez, Camila; Velastegui, Edgar; Martinez-Ruano, Jimmy Anderson; Rivas, Mariella; Jeison, David
    Microbially induced calcite precipitation (MICP) has emerged as a promising technique to contribute to a more sustainable management of mine tailings deposits. While ureolytic activity has been the predominant driver of conventional MICP to date, the associated release of ammonia poses significant environmental hazards. This study explores a novel, environmentally friendly approach by replacing urea with sodium bicarbonate as the carbon source for MICP, with the aim of reducing urea requirements and thus ammonia release. Leveraging the principles of the MICP, it was observed that when urea concentration was reduced to 0.7 M, by replacing it with bicarbonate, surface strength was close to 400 kPa. Furthermore, wind tunnel testing showed a significant reduction in dust emission, where the mass loss rate of the biocemented sample was below 10 kg m⁻ 2 h⁻ 1 , which means a 9-fold reduction compared to untreated samples. So, it was demonstrated that bicarbonate can effectively replace urea, achieving a relevant reduction of up to 75 % in urea use without compromising the surface strength of the biocemented tailings and reducing the environmental hazards of ammonia release. These results highlight the potential of bicarbonate-based MICP as an innovative and sustainable approach to mitigate the environmental impacts associated with tailings deposits.