Dr Guijie Sang
Lecturer Civil and Environmental Engineering
- Work email G.Sang@liverpool.ac.uk
Research
Research Overview
My research focuses on advancing the understanding of coupled Hydraulic-Mechanical-Chemical-Microbiological (HMCM) processes in near-surface and subsurface engineering contexts. I am interested in developing innovative, environmentally sustainable, and industrially applicable approaches to (1) enhance civil and geotechnical infrastructure resilience and (2) support geo-energy projects to meet the UK’s net zero targets.
Microbially induced carbonate precipitation (MICP) for ground improvement
The overarching goal of this topic is to develop an industrially applicable bio-grouting technique for ground improvement. I have collaborated with researchers from the University of Strathclyde (Glasgow) and the construction company BAM Ritchies to achieve this goal. My research began with understanding bacterial transport and attachment in saturated soil, monitoring and modeling hydraulic flow, and effectively delivering MICP fluids to the target treatment zone. I upscaled the MICP process from the column centimeter scale to the meter scale in the laboratory and later supervised a field project at BAM Ritchies (a cubic meter scale MICP trial under environmentally variable conditions).
From a microbiological perspective, my work has involved:
(i) Optimizing the growth of Sporosarcina pasteurii (the bacteria used for MICP) under various conditions such as pH, dissolved oxygen, carbon sources, and additives (e.g., nickel).
(ii) Exploring the spray drying method for long-term storage of Sporosarcina pasteurii to facilitate the industrial implementation of MICP.
I am also interested in studying the MICP process using a microfluidic cell. This work provides insights into the fundamentals of ureolytic bacteria transport in porous media and the coupled hydraulic-(bio)chemical MICP process, serving as a tool to model and optimize the MICP process for ground improvement.
Subsurface storage of hydrogen: role of microbial activity
Throughout my PhD at Pennsylvania State University, I studied hydro-mechanical properties of subsurface rocks (e.g. shale) by investigating water transport and condensation in shale through analysis of sorption isotherms, transport modelling, and in situ small angle neutron scattering (SANS); detecting mechanical damage and failure of shale under cyclic uniaxial loading using in situ acoustic monitoring and coda wave interferometry; characterizing gas-sorption-induced coal swelling under reservoir condition; and quantifying rock-brine-CO2 interactions using SANS, and synchrotron X-ray computed tomography.
I am keen to explore the coupled hydro-mechanical-(bio)chemical processes during hydrogen storage in deep saline aquifers, emphasizing the effects of microbial activity on hydrogen consumption and its byproducts, and alterations in hydromechanical properties.