Abstract

The use of biochar to stabilize soil contaminants is emerging as a technique for remediation of contaminated soils. In this study, an environmental assessment of systems where biochar produced from wood waste with energy recovery is used for remediation of soils contaminated with polycyclic aromatic hydrocarbons (PAH) and metal(loid)s was performed. Two soil remediation options with biochar (on-and off-site) are considered and compared to landfilling. The assessment combined material and energy flow analysis (MEFA), life cycle assess-ment (LCA), and substance flow analysis (SFA). The MEFA indicated that on-site remediation can save fuel and backfill material compared to off-site remediation and landfilling. However, the net energy production by pyrol-ysis of wood waste for biochar production is 38% lower than incineration. The LCA showed that both on-site and off-site remediation with biochar performed better than landfilling in 10 of the 12 environmental impact catego-ries, with on-site remediation performing best. Remediation with biochar provided substantial reductions in cli-mate change impact in the studied context, owing to biochar carbon sequestration being up to 4.5 times larger than direct greenhouse gas emissions from the systems. The two biochar systems showed increased impacts only in ionizing radiation and fossils because of increased electricity consumption for biochar production. They also resulted in increased biomass demand to maintain energy production. The SFA indicated that leaching of PAH from the remediated soil was lower than from landfilled soil. For metal(loid)s, no straightforward conclusion could be made, as biochar had different effects on their leaching and for some elements the results were sensitive to water infiltration assumptions. Hence, the reuse of biocharremediated soils requires further evaluation, with site-specific information. Overall, in Sweden's current context, the biochar remediation technique is an environmentally promising alternative to landfilling worth investigating further.(c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

Keywords

Metal(loid)s; Polycyclic aromatic hydrocarbons; Material and energy flow analysis; Life cycle assessment; Substance flow analysis

Published in

Science of the Total Environment
2021, Volume: 776, article number: 145953
Publisher: ELSEVIER

SLU Authors

• Sundberg, Cecilia

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    
  • Royal Institute of Technology (KTH)

Sustainable Development Goals

Ensure access to affordable, reliable, sustainable and modern energy for all
Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss
Take urgent action to combat climate change and its impacts


UKÄ Subject classification

Environmental Sciences


Publication identifier

DOI: https://doi.org/10.1016/j.scitotenv.2021.145953

Permanent link to this page (URI)

https://res.slu.se/id/publ/112072