Degradation of a Leather-Dye by the Combination of Depolymerised Wood-Chip Biochar Adsorption and Solid-State Fermentation with Trametes Villosa SCS-10

Abstract

Adsorption into biochar-derived materials and mycoremediation are promising technologies for removing dyes from solid and liquid matrices. This study presents a combined treatment with adsorption into wood-chip biochar and mycodegradation under solid-state ermentation by Trametes villosa for removing the leather-dye Acid Blue 161. In the first stage, untreated wood-chip biochar, NaOH-depolymerised-biochar and KMnO 4 -depolymerised-biochar were assessed for their dye removal efficiency by adsorption. KMnO 4 -depolymerised-biochar exhibited the highest adsorption (85.1 ± 1.9%) after 24 h of contact. KMnO 4 -depolymerisation modified some physical and chemical properties on the untreated wood-chip biochar, increasing the surface area (50.4 m 2 g –1 ), pore size (1.9 nm), and resence of surface functional groups. Response Surface Methodology coupled with a Box-Behnken design was used to optimise the AB 161 adsorption into the KMnO 4 -depolymerised-biochar. The optimised conditions, pH 3.0, dye concentration 100 mg L –1 and sorbent dosage 2 g L –1 , led to a higher dye removal efficiency by adsorption (91.9 ± 1.0%). In a second stage, the wood-chip biochar supplemented with nutrients (1% malt extract and 0.5% peptone) was employed as a solid matrix for growing T. villosa and regenerating the dye-saturated material. After 15 days, T. villosa was able to grow (86.8 ± 0.8%), produce Laccase activity (621.9 ± 62.3 U L –1 ), and biodegrade (91.4 ± 1.3%) the dye adsorbed into the KMnO 4 -depolymerised-biochar. Finally, the mycoregenerated was reutilised in a new cycle of adsorption reaching 79.5 ± 2.0% of dye removal efficiency by adsorption. This study revealed the potential of the combined treatment and is an initial assessment for developing commercial alternatives for treating leather industry wastewaters.