TY - JOUR
T1 - Stimulation of native microorganisms for biocementation in samples recovered from field scale treatment depths
AU - Gomez, Michael G.
AU - Graddy, Charles M.R.
AU - DeJong, Jason T.
AU - Nelson, Douglas C.
AU - Tsesarsky, Michael
N1 - Funding Information:
This material is based upon work supported by the National Science Foundation grants CMMI-1539774 and CMMI-1234367, and by the Engineering Research Center Program of the National Science Foundation under NSF Cooperative Agreement No. EEC- 1449501. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. The authors also thank Gabby Hernandez, Alexandra San Pablo, Kevin Kuei, and Andreas Gavras of the University of California, Davis for their assistance with the project and Teichert Aggregates Woodland for providing access to and support with the project testing location.
Publisher Copyright:
© 2017 American Society of Civil Engineers.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - Microbially induced calcite precipitation (MICP) is a biomediated cementation process that uses natural microbial enzymatic activity to improve the geotechnical properties of granular soils. In this study, two sets of experiments are completed using soil samples obtained from different depths to evaluate the feasibility of stimulating native ureolytic microorganisms for MICP at depths relevant to geotechnical applications. Batch and column experiments completed using five different stimulation solutions demonstrate that stimulation of native microbial ureolysis is improved with an enhanced stimulation solution, which differs from a standard stimulation solution used in previous studies through initial solution pH adjustment to 9.0 and higher concentrations of ammonium chloride and yeast extract of 100 mM and 0.2 g/L, respectively. A sterile sampling and column testing program is completed using soil materials obtained at shallow (2 m), middle (5.9 m), and deep (12 m) depths from a geotechnical boring and treated with both standard and enhanced stimulation solutions. Despite significant differences in stimulated urea degradation between soil depths and stimulation solution types, all tested columns achieved ureolysis rates sufficient to induce MICP, although at different times. Following 14 cementation treatments, soil columns achieved final Vs values as high as 1,020 m/s and unconfined compressive strengths as high as 1.9 MPa. The results of this study suggest that native ureolytic microorganisms may be successfully stimulated in natural soil deposits to induce calcite precipitation at treatment depths up to 12 m for geotechnical ground improvement.
AB - Microbially induced calcite precipitation (MICP) is a biomediated cementation process that uses natural microbial enzymatic activity to improve the geotechnical properties of granular soils. In this study, two sets of experiments are completed using soil samples obtained from different depths to evaluate the feasibility of stimulating native ureolytic microorganisms for MICP at depths relevant to geotechnical applications. Batch and column experiments completed using five different stimulation solutions demonstrate that stimulation of native microbial ureolysis is improved with an enhanced stimulation solution, which differs from a standard stimulation solution used in previous studies through initial solution pH adjustment to 9.0 and higher concentrations of ammonium chloride and yeast extract of 100 mM and 0.2 g/L, respectively. A sterile sampling and column testing program is completed using soil materials obtained at shallow (2 m), middle (5.9 m), and deep (12 m) depths from a geotechnical boring and treated with both standard and enhanced stimulation solutions. Despite significant differences in stimulated urea degradation between soil depths and stimulation solution types, all tested columns achieved ureolysis rates sufficient to induce MICP, although at different times. Following 14 cementation treatments, soil columns achieved final Vs values as high as 1,020 m/s and unconfined compressive strengths as high as 1.9 MPa. The results of this study suggest that native ureolytic microorganisms may be successfully stimulated in natural soil deposits to induce calcite precipitation at treatment depths up to 12 m for geotechnical ground improvement.
UR - http://www.scopus.com/inward/record.url?scp=85032172363&partnerID=8YFLogxK
U2 - 10.1061/(ASCE)GT.1943-5606.0001804.
DO - 10.1061/(ASCE)GT.1943-5606.0001804.
M3 - Article
AN - SCOPUS:85032172363
SN - 1090-0241
VL - 144
SP - 1804
JO - Journal of Geotechnical and Geoenvironmental Engineering - ASCE
JF - Journal of Geotechnical and Geoenvironmental Engineering - ASCE
IS - 1
ER -