Coupling chemical oxidation processes and Leptosphaerulina sp. myco-remediation to enhance the removal of recalcitrant organic pollutants in aqueous systems

This research evaluated for the first time, the coupling of chemical oxidation processes with Leptosphaerulina sp. (a Colombian fungus), to degrade a refractory pollutant. For such purpose, a model contaminant (crystal violet, CV) was considered. Initially, the pollutant, at high concentrations (i.e., 200 and 50 mg L-1), was submitted to the fungus action. However, the CV inhibited the growth and enzymatic production of the fungus. Then, three chemical oxidation processes: TiO2-photocatalysis, sonochemistry, or electrochemistry (with a Ti/IrO2 anode in sodium chloride) were used as treatments previous to the myco-remediation. These oxidative treatments led to the pollutant degradation (similar to 100%) by the action of radicals or active chlorine species, but they showed low mineralization. Indeed, the total organic carbon removal (TOC) was 54, similar to 15, and 31% to TiO2-photocatalysis (after 12 h), sonochemistry (after 12 h), and electrochemistry (after 1.33 h), respectively. Thus, the resultant solutions from the chemical oxidations were submitted to the action of Leptosphaerulina sp. (this time effective fungus growth and enzymes production were observed). It was found that the TOC removals by the fungus were 87, 84, and 83% for solutions pre-treated by TiO2-photocatalysis (12 h), sonochemical (12 h), and electrochemical (1.33 h) treatments, respectively. Regarding the enzymatic production, TiO2-photocatalysis/Leatosphaertilina sp., ultrasonication/Leptosphaerulina sp., and electrochemical oxidation/Leptosphaerulina sp. combinations reached the highest activities of lactase (0.6 U mg(-1), at day 15), manganese peroxidase (135 U mg(-1), at day 7) and versatile peroxidase (1.72 U mg(-1), at day 15). respectively. The results from this work evidence feasibility of the pre-treatment with chemical oxidation processes as a strategy to enhance Leptosphaerulina sp. action toward recalcitrant organic pollutants (as CV) in water. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This research evaluated the coupling of chemical oxidation processes with Leptosphaerulina sp. to degrade a refractory pollutant for the first time. Pre-treatment with TiO2-photocatalysis, sonochemistry, or electrochemistry enhanced the fungus's action on pollutant degradation. The study demonstrated the feasibility of using chemical oxidation processes to enhance Leptosphaerulina sp. action towards recalcitrant organic pollutants in water.