Comprehensive utilization of sunflower seed hulls in a Circular Economy model: Production of mushrooms, enzymes, and biogas and biofertilizer

Abstract

This study addresses a Circular Economy proposal to utilize sunflower seed hulls (SSH), an abundant waste in the oilseed industry, as a substrate for the cultivation of edible and medicinal mushrooms, particularly for the Pleurotus genus. This process not only produces food but also generates a by-product, spent mushroom substrate (SMS) with potential for the production of biofertilizers, biogas, and enzymes for bioremediation. The ability of an aqueous extract of SMS to degrade dyes was evaluated, showing a 62% degradation of malachite green, followed by aniline blue (24%). Phenol red showed no significant decolorization. Additionally, the capacity of SMS to produce biogas in co-digestion with bovine manure was evaluated, showing higher production in mixtures with higher dry matter concentration. To close the cycle, it is proposed to use the obtained biogas as an energy source for pasteurization in mushroom cultivation. In conclusion, this strategy offers a sustainable solution that generates both economic and environmental value.