Removal of diclofenac from a non-sterile aqueous system using <i>Trametes versicolor</i> with an emphasis on adsorption and biodegradation mechanisms

Abstract

This paper describes the search for procedures through which the xenobiotic pollutant diclofenac can be removed from non-sterile aquatic systems. Specifically, adsorption to solid supports (carriers) in combination with biodegradation by non-immobilized and immobilized white rot fungus <i>Trametes versicolor</i> were investigated. Batch experiments using polyurethane foam (PUF)-carriers resulted in 99.9% diclofenac removal after 4 h, with monolayer adsorption of diclofenac to carrier and glass surfaces accounting for most of the diclofenac decrease. Enzymatic reactions contributed less, accounting for approximately < 0.5% of this decrease. In bioreactor experiments using PUF-carriers, an initial 100% removal was achieved with biodegradation contributing approximately 7%. In batch experiments that utilized polyethylene-carriers with negligible immobilization of <i>Trametes versicolor</i>, a 98% total diclofenac removal was achieved after one week, with a biodegradation contribution of approximately 14%. Five novel enzyme-catalyzed biodegradation products were tentatively identified in the batch-wise and bioreactor experiments using full scan ultra-high-performance liquid chromatography-quadrupole/time of flight mass spectrometry. Both reduction and oxidation products were found, with the contents estimated to be at µg L^-1 concentration levels.