Discoloration of rhodamine b dye by white-rot fungi in solid bleached sulfate paperboard coated with polyethylene terephthalate: scale-up into non-sterile packed-bed bioreactor

Abstract Treatment of dye-contaminated effluents and proper disposal of solid waste from the processing industry has been intensely studied. The use of basidiomycetes fungi has been highlighted over conventional treatments using green technologies. This work presents the first scale-up of a rhodamine B discoloration under non-sterile conditions using solid bleached sulfate (SBS) paperboard coated with polyethylene terephthalate (PET) by filamentous fungi. The dye discoloration was conducted first in agar plates and then in flasks and packed-bed bioreactor with SBS/PET. The fungus Agaricus brasiliensis (EF 03) presented the best dye discoloration results (42.94 ± 0.64) in agar plates. Optimization studies (flasks) of the culture medium showed a higher percentage of discoloration (93.65 ± 4.60) by A. brasiliensis (EF 03) when cultivated in solid-state fermentation with SBS/PET waste and Socarean medium and sodium nitrate variables. The pilot packed-bed bioreactor scaled-up and optimized medium were successful in discoloring of rhodamine B. The fungal population, later identified as the genera Agaricus and Phlebia by rRNA gene sequencing approach, was predominant up to 30 days and the highest laccase peaks were observed in 20 days (198.44 IU L−1) and 45 days (203.47 IU L−1). This packed-bed bioreactor operated with filamentous fungi in solid-state fermentation proved suitable for the discoloration of rhodamine B dye for 51 days, for repeated fed-batch under non-sterile conditions.