Nutrient recovery from apple pomace waste by vermicomposting technology

• Earthworms were able to convert apple pomace waste into a value added product.
• The addition of straw to apple pomace did not enhance earthworm biomass.
• The resulting vermicomposts were characterized by slightly acidic to neutral pH.
• The total content of nutrients increased during vermicomposting.

The present work was focused on vermicomposting apple pomace waste and its mixtures with straw in volume proportions of 25%, 50%, and 75%. The feasibility was evaluated on the basis of agrochemical properties and earthworm biomass. Vermicomposting was able to reduce the weight and volume of the feedstock by 65% and 85%, respectively. The resulting vermicomposts were characterized by slightly acidic to neutral pH (5.9–6.9), and optimal EC (1.6–4.4 mS/cm) and C:N ratios (13–14). The total content of nutrients increased during vermicomposting for all of the treatments with the following average final values: N = 2.8%, P = 0.85%, K = 2.3%, and Mg = 0.38%. The addition of straw to apple pomace did not enhance earthworm biomass, but did increase the available content of nutrients during vermicomposting. The data reveals that vermicomposting is a suitable technology for the decomposition of apple pomace waste into a value added product.