Bioremediation of Remazol Red Dye Using Calcium Carbonate–Immobilized Fungal Strains Aspergillus niger TB1, Cladosporium cladosporioides TB31, and Trametes polyzona TB4

Large volumes of textile industrial effluent containing toxic synthetic dyes pose severe environmental hazards. However, the operational effectiveness of mineral-associated fungal pellets for dye removal remains insufficiently clarified. This study evaluated the decolorization performance of CaCO3-associated fungal pellets prepared from three native strains—Aspergillus niger TB1, Cladosporium cladosporioides TB31, and Trametes polyzona TB4—for the removal of Remazol Red (RR) dye (100 mg/L), while assessing biomass weight and oxidative enzyme dynamics (manganese peroxidase [MnP], lignin peroxidase [LiP], and laccase [Lac]). A completely randomized factorial design was employed across four treatments: (A) CaCO3-associated fungal pellets, (B1) free mycelial pellets, (B2) free mycelial pellets with separate CaCO3 addition, and (C) abiotic control without fungi or CaCO3. Destructive sampling was conducted in triplicates (n = 3) at 2, 4, 6, 16, 20, 24, 48, 72, and 96 h. Three-way ANOVA demonstrated that the interaction among fungal strain, treatment formulation, and incubation time significantly affected decolorization. Treatment A markedly enhanced process performance over other treatments; maximum decolorization reached 98.2% at 96 h using T. polyzona TB4 under Treatment A. Furthermore, MnP activity peaked earlier than LiP and Lac, reaching maximum levels of 100 U/mL in Treatment A. These findings demonstrate that CaCO3-associated fungal pelletization substantially enhances dye decolorization efficiency, fungal biomass yield, and oxidative enzyme production.