Fungal solid state fermentation on agro-industrial wastes for acid wastewater decolorization in a continuous flow packed-bed bioreactor

This study was aimed at developing a process of solid state fermentation (SSF) with the fungi Pleurotus ostreatus and Trametes versicolor on apple processing residues for wastewater decolorization. Both fungi were able to colonize apple residues without any addition of nutrients, material support or water. P. ostreatus produced the highest levels of laccases (up to 9 U g−1 of dry matter) and xylanases (up to 80 U g−1 of dry matter). A repeated batch decolorization experiment was set up with apple residues colonized by P. ostreatus, achieving 50% decolorization and 100% detoxification after 24 h, and, adding fresh wastewater every 24 h, a constant decolorization of 50% was measured for at least 1 month. A continuous decolorization experiment was set up by a packed-bed reactor based on colonized apple residues achieving a performance of 100 mg dye L−1 day−1 at a retention time of 50 h.

► A process of solid state fermentation (SSF) with the fungi Pleurotus ostreatus and Trametes versicolor on apple processing residues was developed for production of ligninolytic and (hemi)cellulolytic enzymes and wastewater decolourization. ► P.ostreatus produced the highest levels of laccases (up to 9 U g−1 of dry matter, at the 3rd day) and xylanases (up to 80 U g−1 of dry matter, at the 4th day). ► A continuous decolourization experiment was set up by a packed-bed reactor based on apple residues colonized by P. ostreatus, achieving a performance of 100 mg dye L−1 day−1 at a retention time of 50 h.