Mycoremediation of Tunisian tannery wastewater under non-sterile conditions using Trametes versicolor: live and dead biomasses

Abstract

Tannery wastewater contains high concentration of pollutants (nitrogen, organic matter, toxic metals, etc.). The present study investigated the efficiency of mycoremediation on the removal of organic and inorganic pollutants and the reduction of the toxicity from a tannery wastewater (TW) using live and dead biomasses of Trametes versicolor under non-sterile conditions. Batch experiments were carried out at the normal pH of the raw TW (8.25) and at pH = 5.5. Monitoring of chemical oxygen demand (COD) reduction, chromium removal (Cr), laccase activity, color and toxicity removals, and the fungal functional groups involved in the mycoremediation was conducted before and after the treatment. The results revealed that COD removal using live biomass was significantly higher (31.2% for pH = 8.25 and 45% for pH = 5.5) than the removal obtained using dead biomass (only 19%). Laccase activity reached a maximum of 7.975 U/L (pH = 8.25) and 20 U/L (pH = 5.5) after 5 days of treatment. Color and Cr removal reached a maximum of 66% and 80%, respectively, for live biomass at pH = 5.5. FTIR spectra revealed the involvement of hydroxyl amino, phospholipids, carboxylic, and carbonyl groups in the elimination of TW pollutants. The phytotoxicity test showed that the decrease in the toxicity levels was significantly higher for live biomass, reaching 44.1% at pH = 5.5 and did not exceed 33% for dead biomass. Overall, this study advocates the potential of TW mycoremediation under non-sterile conditions and the efficiency of live biomass compared to dead biomass in reducing the organic and inorganic pollutants and consequently the toxicity levels in the TW.