Remediation of bentazone contaminated water by Trametes versicolor: characterization, identification of transformation products, and implementation in a trickle-bed reactor under non-sterile conditions

TL;DR

This study demonstrates that Trametes versicolor can effectively degrade bentazone in water through enzymatic activity, identifying transformation products and successfully implementing a non-sterile trickle-bed reactor for potential real-world bioremediation.

Contribution

It is the first to evaluate fungal bioremediation of bentazone at a pilot scale using a trickle-bed reactor under non-sterile conditions.

Findings

Complete removal of bentazone in Erlenmeyer incubation within three days.

Identification of 19 transformation products involving hydroxylations, oxidations, methylations, N-nitrosation, and dimerization.

Achieved 48% removal efficiency over 30 days in a pilot-scale reactor, with stable performance despite bacterial contamination.

Abstract

Bentazone, an herbicide widely applied in rice and cereal crops, is widespread in the aquatic environment. This study evaluated the capacity of Trametes versicolor to remove bentazone from water. The fungus was able to completely remove bentazone after three days at Erlenmeyer-scale incubation. Both laccase and cytochrome P450 enzymatic systems were involved in bentazone degradation. A total of 19 transformation products (TPs) were identified to be formed during the process. The reactions involved in their formation included hydroxylations, oxidations, methylations, N-nitrosation, and dimerization. A laccase mediated radical mechanism was proposed for TP formation. In light of the results obtained at the Erlenmeyer scale, a trickle-bed reactor with T. versicolor immobilized on pine wood chips was set up to evaluate its stability during bentazone removal under non-sterile conditions. After 30 days of sequencing batch operation, an average bentazone removal of 48 % was obtained, with a considerable contribution of adsorption onto the lignocellulosic support material. Bacterial contamination, which is the bottleneck in the implementation of fungal bioreactors, was successfully addressed by this particular system according to its maintained performance. This research is a pioneering step forward to the implementation of fungal bioremediation on a real scale.