Coupling phytoremediation of Pb-contaminated soil and biomass energy production: A comparative Life Cycle Assessment

Phytoremediation is an in-situ remediation technology based on the ability of plants to fix pollutants from the soil. In this sense, plants such as Festuca arundinacea are a promising for heavy metal removal in contaminated soils. The present work studies phytoremediation for Pb removal from a contaminated soil located in Spain using F. arundinacea by applying the Life Cycle Assessment (LCA) approach. Two different options for biomass management were assessed: direct disposal in a security landfill (case 1A) and energy recovery (case 1B). For the latter option, cogeneration was simulated using SuperPro Designer 9.5. In addition, traditional treatments such as soil washing (case 2) and excavation + landfill (case 3) were evaluated in terms of environmental impacts by LCA. The former was simulated using SuperPro Designer 9.5, whereas data from literature were used for the latter to perform the LCA. Results showed that biomass disposal in a landfill was the most important contributor to the overall impact in case 1A. In contrast, biomass conditioning and cogeneration were the main steps responsible for environmental impacts in case 1B. Comparing cases 1A and 1B, the energy recovery from biomass was superior to direct landfill disposal, reducing the environmental impacts in most of the studied categories. Regarding the rest of the treatments, chemical production and soil disposal presented the most critical environmental burdens in cases 2 and 3, respectively. Finally, the comparison between the studied cases revealed that phytoextraction + energy recovery was the most environmentally friendly option for the studied conditions, reducing impacts by 30–100%.