Fed-batch bioreactor intensifies degradation and detoxification of anthraquinone dyes by an immobilized white-rot fungal consortium.

The textile industry produces enormous quantities of highly polluted wastewater that is usually contaminated with recalcitrant dyes, salts, and toxic metals; hence, it urgently requires efficient and sustainable treatment strategies. Considering the above scenario, mycoremediation using an immobilized white rot fungal consortium (WRFC) of Trametes cubensis OR394063, Polyporus umbellatus OR398647, Leiotrametes flavida MTCC 12927, and Pleurotus pulmonarius MTCC 1805 was used in the present study to treat Anthraquinone (AQ) dye-induced synthetic textile effluent (STE) in batch, continuous, and fed-batch bioreactors. The prepared STE was composed of 200 mg/L mixed AQ dyes (Acid Blue 129, Alizarin Cyanin Green, Remazol Brilliant Blue R) along with high levels of salts, surfactants and heavy metals to simulate real textile wastewater. Among the three reactor configurations, the highest decolorization efficiency (99.06 ± 3.5%) of AQ dyes was observed in the fed-batch reactor within 120 h, followed by continuous (93.68 ± 3.5%), and batch (91.99 ± 3.6%). Enhanced activities of laccase (0.67 ± 0.01 U/mL), Lignin Peroxidase (LiP) (79.25 ± 0.33 U/mL), and Manganese Peroxidase (MnP) (157.35 ± 0.53 U/mL) were observed within 64 h in the fed-batch reactor. The kinetic studies showed that the degradation of AQ dyes in all reactors followed pseudo-first-order kinetics. Also, significant reduction in COD (75.04 ± 0.50%), BOD (96.05 ± 0.25%), TDS (65.96 ± 0.15%) and heavy metals such as Cd (50.00 ± 2.40%) and Pb (39.47 ± 2.20%) were observed in the fed-batch reactor compared to the batch and continuous systems. Moreover, the toxicity assessments using Vigna radiata and Allium cepa showed significant decrease in the toxicity of the treated effluent, particularly for the fed-batch process as evidenced by increased germination index (99.39 ± 0.29%), decrease in the phytotoxicity % (14.51 ± 0.31%), relative toxicity (16.12 ± 0.33%) and mitotic index (8.89 ± 0.19%) and reduced chromosomal aberrations (7.35 ± 0.28%).