Degradation of aniline via microbial treated post Fe(II) or Co(II)/PMS advanced oxidation processes

Abstract

Aniline, a common derivative pollutant found in non-ferrous metal(loid) tailings due to the usage of flotation reagents, is a significant residual chemical and requires remediation in tailings waste management. This research identified a Staphylococcus aureus CUGB-LJL5 as a proficient aniline-degrading bacterium isolated from tailings soil. This strain was successfully used to establish a two-step strategy of microbiological treatment followed by an advanced oxidation process (AOP) to eliminate high concentrations of aniline (1000 mg/L). The results indicate that the combined microbial AOPs technique exhibits superior efficiency in degrading aniline at high concentration of 1000 mg/L, achieving a degradation rate of 99.89% with only 1.08 mg/L remaining. Optimal conditions for this process involved the addition of 5 mM peroxymonosulfate (PMS) and 1 mM Fe(II) after inoculating with a 3% bacterial culture for 96 h at a pH of 7 and a temperature of 30°C. PCR and radical scavenger experiments suggest that the microbial phase primarily involves enzyme-mediated removal, while the subsequent AOPs phase was mainly driven by free radical (SO₄^•-) reactions. Three different degradation pathways are proposed based on the aniline degradation byproducts determined by GC–MS. Including the elimination of aniline by the aniline dioxase pathway during microbial degradation and promotes further mineralization by Fe(II) or Co(II)/PMS by both, hydroxylation and acetylation. Additionally, results from the cost analysis also highlight the potential and economic feasibility of the combined technology. In general, microbiological treatment post Fe(II)/PMS process is a green, efficient and economical method for remediating high concentrations of aniline in non-ferrous(loid) tailings environments.