Environmental impact of recycling digested food waste as a fertilizer in agriculture—A case study

•Digested food waste contributed to larger GWP than chemical fertilizer.•Digestate fertilizer used more primary energy than chemical fertilizer.•Paper bags, methane losses and digestate handling were large contributors to GWP.•Digestion of food waste can surpass incineration if the above aspects are...

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Bibliographic Details
Published in:Resources, conservation and recycling conservation and recycling, 2015-02, Vol.95, p.1-14
Main Authors: Chiew, Yoon Lin, Spångberg, Johanna, Baky, Andras, Hansson, Per-Anders, Jönsson, Håkan
Format: Article
Language:English
Subjects:
Biogas production
Cadmium
Digestate
Energisystem
Energy Systems
Environmental Management
Eutrophication
Fertilizer
Fertilizing
Food waste treatment
Foods
LCA
Miljöledning
Phosphates
Recycling
Rock
Wastes
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Summary:•Digested food waste contributed to larger GWP than chemical fertilizer.•Digestate fertilizer used more primary energy than chemical fertilizer.•Paper bags, methane losses and digestate handling were large contributors to GWP.•Digestion of food waste can surpass incineration if the above aspects are improved.•Digested food waste added relatively large amounts of cadmium to arable soil. This study assessed the environmental impacts of recycling the plant nutrients in anaerobically digested food waste as fertilizer in agriculture. This was compared with the impacts of using chemical fertilizer, where the food waste was incinerated, producing heat. The study site was a biogas plant in central Sweden and life cycle assessment methodology was used. The impacts studied were primary energy use, global warming potential (GWP), potential acidification, potential eutrophication, cadmium flow to farmland and use of phosphate rock. Use of digested food waste as fertilizer proved to have larger negative results than use of chemical fertilizer in all categories assessed except use of non-renewable phosphate rock. Sensitivity analyses showed that the scenarios were comparable in terms of primary energy use and better for GWP if some improvements in the anaerobic digestion system were made. However, acidification and eutrophication caused by digestate handling and the cadmium content of digestate should still be considered.
ISSN:0921-3449
1879-0658
1879-0658
DOI:10.1016/j.resconrec.2014.11.015