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Conference paper2021Peer reviewed

Circularity in practice: reusing restaurant waste for in-house vegetable production

Asp, Håkan; Bergstrand, Karl-Johan; Hultberg, Malin


Production of biogas is a common way to handle organic waste products and it provides not only energy but also an anaerobic digestate (AD) rich in plant nutrients. In order to create a close loop between food consumption and vegetable production this project was undertaken to see if food waste from a restaurant, could be used to produce a liquid fertilizer for lettuce production to the same restaurant. Growth experiments in a hydroponic set up were made with nitrified AD. The AD was tested as a hydroponic fertilizer at two dilution levels. In one trial the solution was also amended with mineral nutrients and all the trials were compared to a mineral nutrient control. Results indicate that it is possible to use the digestate as a fertilizer for lettuce, and that amendment with certain mineral nutrients enhances the growth. Plant concentrations of Na and Cl indicates that there might be a problem with toxicity but it was not clarified by these experiments.


anaerobic digestate; food waste; hydroponic production; lettuce

Published in

Acta Horticulturae
2021, number: 1317, pages: 281-286


II International symposium on growing media, soilless cultivation, and compost utilization in horticulture, 210823-210827, Ghent, Belgium