Evaluation of the textile dye removal process using the residual substrate from Pleurotus ostreatus mushroom production

The release of textile effluents without treatment, or subjected to ineffective treatment, causes serious problems in aquatic ecosystems. In this context, the objective of this study was to evaluate the capacity and process of removing the textile dye Drimaren Red CL-7B, using the residual compound resulting from the production of the Pleurotus ostreatus mushroom. For this purpose, a 32 experimental planning was first developed, considering the variables pH and substrate concentration, seeking to evaluate the removal of dye from synthetic textile effluent, during six hours of contact time. The substrate concentrations applied to the effluent were 50, 100 and 150 g L-1 and the pH values used were 5, 7 and 9. After determining the best experimental condition among those evaluated, the possible removal mechanisms that occurred and the evaluation of the enzymatic activity of the mycelium present in the substrate were also studied. It was found that the best operational condition was obtained at pH 5 and concentration of 150 g L-1. Under these conditions, the achieved dye removal efficiency was close to 70%. It was observed that the main removal mechanism was adsorption and a contact time of 30 minutes already allows to obtain satisfactory results. Additionally, the results of the laccase activity demonstrated that its efficiency is high under acidic pH conditions and it becomes inactive under alkaline pH conditions. It was concluded that the residual substrate has high potential for the treatment of textile effluents due to the simultaneous action of lignolytic enzymes and adsorption in the removal of dyes, as well as the possibility of valuing an agro-industrial residue.