Augmented complete mineralization of glyphosate in wastewater via microbial degradation post CWAO over supported Fe-CNF

Glyphosate, a widely used post emergence broad spectrum herbicide, recognized for its harmful impact on the environment, is sequentially mineralized in a two-step process: catalytic wet air oxidation (cWAO) followed by microbial degradation. Iron nanoparticle (Fe NP)-tipped carbon nanofibers (CNFs) supported over activated carbon beads (ACBs) are used as a cWAO catalyst. Fe-CNF/ACB with a high specific surface area (similar to 296 m(2)/g), high thermal stability (25-1100 degrees C) and an increased exposure of the Fe NPs to the surrounding water causes similar to 70% degradation of the aqueous glyphosate (100 mg/L) in 2 h at 220 degrees C, 25 bar-air pressure, and 0.75 g/L of catalyst-dose. The residual glyphosate is, however, completely mineralized in the next 2 h at 37 degrees C, with 100% reduction in total organic carbon content, using a bacterium isolated from the industrial wastewater. The bacterium is phylogenetically identified as Providencia vermicola via 16s rRNA analysis. Non-toxicity of Fe-CNF/ACB towards the isolated bacterial strain eases the sequential remediation process by circumventing the necessity of removing the spent catalyst from the reaction mixture before switching over to microbial degradation. The present approach based on cWAO followed by microbial degradation is indicated to be efficient for the degradation and mineralization of toxic, biorefractory pollutants in wastewater.

Automated summary

Glyphosate, a commonly used herbicide known for its detrimental impact on the environment, is effectively mineralized through a two-step process involving catalytic wet air oxidation (cWAO) and microbial degradation. Iron nanoparticle-tipped carbon nanofibers supported on activated carbon beads serve as the cWAO catalyst, leading to significant degradation of glyphosate followed by complete mineralization with the assistance of a bacteria strain identified as Providencia vermicola. The non-toxicity of the catalyst towards the bacteria strain simplifies the remediation process, making it a promising approach for treating toxic pollutants in wastewater.