Hotspot Life Cycle Assessment for Environmental Impacts of EICP for Ground Improvement

As part of the development of the emerging technology of enzyme induced carbonate precipitation (EICP), a hotspot, attributional life cycle analysis (LCA) was performed. EICP is a ground improvement technology that binds soil particles together with calcium carbonate precipitation via hydrolysis of urea. EICP seeks to replace traditional soil improvement methods. The purpose of this hot spot LCA was to proactively assess environmental benefits and costs and identify potential unintended consequences for the EICP process. This LCA considered the main components of the EICP treatment solution (urea, calcium, urease enzyme, and nonfat milk powder) with the aim to see if a particular component stood out in the assessment for three environmental impact indicator areas: energy use, CO₂-equivalent air emissions, and eutrophication potential. The results show that urea is responsible for 63% of energy use and 37% of CO₂-eq air emissions, nonfat milk powder is responsible for 38% of CO₂-eq air emissions, and the ammonium byproducts of the EICP process is responsible for 97% of eutrophication potential of EICP. Means for reducing these impacts include finding greener sources of urea, using waste milk as the source for nonfat milk powder, and extracting ammonium chloride from the ground after completion of EICP treatment.