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

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.

II International Symposium on Growing Media, Soilless Cultivation, and Compost Utilization in Horticulture

H. Asp, K.-J. Bergstrand, M. Hultberg

anaerobic digestate, food waste, hydroponic production, lettuce

https://doi.org/10.17660/ActaHortic.2021.1317.32