Processing of food industry waste streams by compost worms: Experiments in 2021

This report describes five experiments to observe the growth of Dendrobaena veneta and Eisenia fetida on substrates originating from Avebe (potato starch and protein producer), Holland Malt (maltings) or others ( kitchen and garden wastes). The substrates include Tarra (Avebe), Secondary food industry Sludge (Holland Malt and Avebe), Barley Dust (Holland Malt), Germinated Barley (Holland Malt), Bokashi (Jansen Wijhe), Potato Peels (van Vulpen voeders), vegetable fruit and garden waste (van der Wal and Ogar), Apple pulp (van Vulpen voeders), Champost (Koolen champignons CNN) and Carrot and Pumpkin Peels (van Vulpen voeders). The compost worms’ growth was monitored for 4-6 weeks. The compost worms were able to convert the substrates into dry, light and powdery vermicompost high in nutrients and organic matter. The compost worms themselves increased in biomass and produced eggs. The protein content of the compost worms ranged between 57.1 and 68.3 % of DM, whereas the fat content ranged between 7.8 and 9.1% of DM. Tarra and Secondary food industry Sludge (Avebe) are suitable substrates for vermicomposting, when mixed with other substrates. Germinated Barley and Secondary Food Industry Sludge (Holland Malt) are less suitable for vermicomposting, due to substrate instability, even when mixed with other substrates. Additions of barley dust and chalk make the substrates’ texture and composition more suitable for the worms to feed on.