The effect of dissolved organic matter on soybean peroxidase-mediated removal of triclosan in water

•DOM significantly suppressed triclosan (TCS) removal by soybean peroxidase (SBP).•Phenolic moiety of DOM was the active substrate of SBP, and competitive with TCS.•Cross-coupling between DOM and TCS affected products distribution of TCS.•Self-coupling or co-polymers of TCS with DOM was innocuous to the growth of alga.

Dissolved organic matter (DOM) is ubiquitous in water and involved in numerous important chemical processes in aqueous systems, enabling it a unique challenge for a variety of water treatment processes. Soybean peroxidase (SBP)-based enzymatic process, as a promising treatment technique, has been successfully applied to remove pollutants in wastewaters such as coal-tar and refinery wastewater. In this study, the effect of DOM on the removal of polychlorinated aromatic antimicrobials triclosan (TCS) by SBP was investigated. Our results suggested that DOM significantly suppressed the catalytic performance of SBP to TCS, presumably resulting from the competition of the phenolic moiety in DOM structure as the active substrate of SBP via the analysis of excitation emission matrix (EEM) spectra of DOM. Although the product species of TCS in SBP-mediated system with DOM has no change compared with the system without DOM, the yields of self-coupling products relative to total transformed TCS were remarkably reduced in the presence of DOM, suggesting that DOM participated in the oxidative coupling reactions. Cross-coupling between TCS and DOM was also verified using guaiacol as a model DOM constituent. Moreover, the products including self-coupling products and co-polymers in SBP-mediated TCS reaction system with DOM were innocuous through growth inhibition assay of S. obliquus.