Microbially Enhanced Carbon Capture and Storage by Mineral-Trapping and Solubility-Trapping

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• 作者：Andrew C. Mitchell ; Knud Dideriksen ; Lee H. Spangler ; Alfred B. Cunningham ; Robin Gerlach
• 刊名：Environmental Science & Technology
• 出版年：2010
• 出版时间：July 1, 2010
• 年：2010
• 卷：44
• 期：13
• 页码：5270-5276
• 全文大小：255K
• 年卷期：v.44,no.13(July 1, 2010)
• ISSN：1520-5851

文摘

The potential of microorganisms for enhancing carbon capture and storage (CCS) via mineral-trapping (where dissolved CO₂ is precipitated in carbonate minerals) and solubility trapping (as dissolved carbonate species in solution) was investigated. The bacterial hydrolysis of urea (ureolysis) was investigated in microcosms including synthetic brine (SB) mimicking a prospective deep subsurface CCS site with variable headspace pressures [p(CO₂)] of ¹³C−CO₂. Dissolved Ca²⁺ in the SB was completely precipitated as calcite during microbially induced hydrolysis of 5−20 g L⁻¹ urea. The incorporation of carbonate ions from ¹³C−CO₂ (¹³C−CO₃²⁻) into calcite increased with increasing p(¹³CO₂) and increasing urea concentrations: from 8.3% of total carbon in CaCO₃ at 1 g L⁻¹ to 31% at 5 g L⁻¹, and 37% at 20 g L⁻¹. This demonstrated that ureolysis was effective at precipitating initially gaseous [CO₂(g)] originating from the headspace over the brine. Modeling the change in brine chemistry and carbonate precipitation after equilibration with the initial p(CO₂) demonstrated that no net precipitation of CO₂(g) via mineral-trapping occurred, since urea hydrolysis results in the production of dissolved inorganic carbon. However, the pH increase induced by bacterial ureolysis generated a net flux of CO₂(g) into the brine. This reduced the headspace concentration of CO₂ by up to 32 mM per 100 mM urea hydrolyzed because the capacity of the brine for carbonate ions was increased, thus enhancing the solubility-trapping capacity of the brine. Together with the previously demonstrated permeability reduction of rock cores at high pressure by microbial biofilms and resilience of biofilms to supercritical CO₂, this suggests that engineered biomineralizing biofilms may enhance CCS via solubility-trapping, mineral formation, and CO₂(g) leakage reduction.