Understanding the Effect of Environmental Conditions on Bio-Based Ground Improvement Strategies for Infrastructure Resilience

Abstract:

We are developing a biogeochemical model to investigate the behavior of Microbially Induced Desaturation and Precipitation (MIDP) via denitrification as a potentially non-disruptive bio-based ground improvement technique under existing structures. Urban infrastructure is becoming increasingly vulnerable to climate change and its associated threats. Current ground improvement techniques to improve the resiliency of existing infrastructure can be costly, impractical, and unsustainable. The results of this model will be used to compare MIDP to current ground improvement techniques. MIDP has been shown to improve the ground in laboratory-based conditions and at field-scale in two ways: 1) biogenic gas desaturation in the short-term (treatment within hours to days) and 2) calcium carbonate precipitation and soil strengthening in the long-term (treatment within weeks to months). We aim to identify the best MIDP recipe (i.e., using acetate or glucose as the electron donor) under varying environmental biochemical conditions when considering de-ionized water, drinking water, groundwater, and seawater as the substrate recipe solute. We compare the predicted products and by-products when aiming for desaturation and/or precipitation as the ground improvement mechanism under all conditions. In the model, we consider resource competition between denitrifiers and other present microbial species (e.g., sulfate reducers), along with microbial inhibitions, including from free nitrous acid, salinity, and hydrogen sulfide. The comparison has demonstrated that substrate selection and environmental conditions significantly affect the process performance in terms of yield and rate. These details are critical to develop comprehensive treatment plans for upcoming field trials to demonstrate MIDP treatment effectiveness and develop process considerations for the wide range of future applications.