Application of untreated versus pyrolysed sewage sludge in agriculture: A life cycle assessment
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Application of untreated versus pyrolysed sewage sludge in agriculture : A life cycle assessment. / Rydgård, Maja; Bairaktari, Asimina; Thelin, Gunnar; Bruun, Sander.
In: Journal of Cleaner Production, Vol. 454, 142249, 2024.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Application of untreated versus pyrolysed sewage sludge in agriculture
T2 - A life cycle assessment
AU - Rydgård, Maja
AU - Bairaktari, Asimina
AU - Thelin, Gunnar
AU - Bruun, Sander
N1 - Funding Information: Sander Bruun reports financial support was provided by European Union Horizon 2020. Gunnar Thelin reports a relationship with EkoBalans Fenix AB that includes: board membership, employment, and equity or stocks. Funding Information: We thank Tobias Pape Thomsen for his support with energy balance calculations. We are grateful to the European Union\u2019s Horizon 2020 Framework and the FertiCycle project (Grant No. 860127) for their full support during this work.
PY - 2024
Y1 - 2024
N2 - Recycling of phosphorus (P) from waste streams such as sewage sludge to agriculture is essential in order to ensure future food security. Land application of sewage sludge is controversial due to its content of pollutants, such as heavy metals and toxic organic compounds. Pyrolysis is a technology that can eliminate harmful contaminants while enabling the recycling of P in the sludge. Organic pollutants are degraded during pyrolysis, while most of the P remains and approximately 40 % of the carbon is retained in a stable form in the biochar. When performing pyrolysis at a temperature of around 800 °C or more, cadmium is evaporated and can be separated from the biochar. Electricity-driven pyrolysis facilitates this by means of easier temperature control. The aim of the present study was to undertake a Life Cycle Assessment (LCA) to evaluate the environmental impacts of high-temperature electricity-driven pyrolysis of sewage sludge, including the separation of cadmium, and field application of sludge biochar as compared with sewage sludge storage and field application. The results showed that pyrolysis can offer a more climate-friendly solution due to avoided greenhouse gas emissions from the sludge and to carbon sequestration of the biochar. However, field application of untreated sludge resulted in a higher application of nitrogen (N) and more plant-available P. Agricultural modelling tools indicated that this produces higher crop yields than biochar application. In the LCA model, higher crop yields lead to savings in land use and water consumption as the higher yields can replace other crop production. The lower plant availability of biochar P implies a possible risk of lower yields when the P application is restricted based on total P, and a risk of greater P loss with soil erosion to the environment. Overall, the present study stresses the importance of including the long-term agronomic impacts of sludge and biochar field application in LCAs, and highlights the trade-offs that need to be considered in decision-making regarding the implementation of pyrolysis technology.
AB - Recycling of phosphorus (P) from waste streams such as sewage sludge to agriculture is essential in order to ensure future food security. Land application of sewage sludge is controversial due to its content of pollutants, such as heavy metals and toxic organic compounds. Pyrolysis is a technology that can eliminate harmful contaminants while enabling the recycling of P in the sludge. Organic pollutants are degraded during pyrolysis, while most of the P remains and approximately 40 % of the carbon is retained in a stable form in the biochar. When performing pyrolysis at a temperature of around 800 °C or more, cadmium is evaporated and can be separated from the biochar. Electricity-driven pyrolysis facilitates this by means of easier temperature control. The aim of the present study was to undertake a Life Cycle Assessment (LCA) to evaluate the environmental impacts of high-temperature electricity-driven pyrolysis of sewage sludge, including the separation of cadmium, and field application of sludge biochar as compared with sewage sludge storage and field application. The results showed that pyrolysis can offer a more climate-friendly solution due to avoided greenhouse gas emissions from the sludge and to carbon sequestration of the biochar. However, field application of untreated sludge resulted in a higher application of nitrogen (N) and more plant-available P. Agricultural modelling tools indicated that this produces higher crop yields than biochar application. In the LCA model, higher crop yields lead to savings in land use and water consumption as the higher yields can replace other crop production. The lower plant availability of biochar P implies a possible risk of lower yields when the P application is restricted based on total P, and a risk of greater P loss with soil erosion to the environment. Overall, the present study stresses the importance of including the long-term agronomic impacts of sludge and biochar field application in LCAs, and highlights the trade-offs that need to be considered in decision-making regarding the implementation of pyrolysis technology.
KW - Agricultural modelling
KW - Biochar
KW - Biosolids
KW - Environmental impact assessment
KW - LCA
KW - Agricultural modelling
KW - Biochar
KW - Biosolids
KW - Environmental impact assessment
KW - LCA
U2 - 10.1016/j.jclepro.2024.142249
DO - 10.1016/j.jclepro.2024.142249
M3 - Journal article
AN - SCOPUS:85191394972
VL - 454
JO - Journal of Cleaner Production
JF - Journal of Cleaner Production
SN - 0959-6526
M1 - 142249
ER -
ID: 393774769