Life cycle sustainability assessment of enzyme-induced carbonate precipitation (EICP) for fugitive dust control
Fugitive dust caused by infrastructure construction reduces air quality and may cause serious respiratory problems. Earthwork contractors apply dust control strategies to meet environmental regulations for dust mitigation. A life cycle sustainability assessment (LCSA) was performed to compare the impacts of two dust control methods: water application—currently considered the best available technology by industry—and enzyme-induced carbonate precipitation (EICP), a new bio-mediated technology being developed at Arizona State University. For each dust control method, indicators of resource depletion (e.g., primary energy and water consumption), climate change (e.g., global warming potential), acidification, eutrophication, respiratory inorganics, ozone depletion, and smog formation were evaluated. The system boundary of the LCSA included the raw materials extraction, materials and energy processing, transportation, and treatment phases of the life cycle for each method. The potential impacts associated with water application exceed those of EICP across all impact categories, except acidification, eutrophication, human health particulate, and ozone depletion potentials. The transportation phase is the primary contributor to impacts for water application due to the need for daily treatments. In contrast, most of the impacts of EICP stem from materials processing and EICP process emissions. In arid climates where runoff to surface or ground water is of little concern, EICP process emissions depend largely on the volatilization of ammonia following the application of EICP on the soil. With respect to the economic impacts of each method, water application costs nearly double EICP. A sensitivity analysis was performed to evaluate the effects of critical modeling assumptions, such as ammonia losses from volatilization and watering frequency. Due to its predicted impacts, EICP is potentially more sustainable than water application, particularly as watering frequency increases. With further development focused on preventing EICP process emissions and reducing production costs, EICP could become more viable for fugitive dust control.