Enhanced biodegradation of triclosan by means of gamma irradiation

- Triclosan was irradiated to improve its biodegradability.
- Irradiation at 1-5 kGy could enhance its mineralization and dechlorination.
- Triclosan was removed by combined irradiation and biodegradation process.
- The kinetics and pathway of triclosan degradation was proposed.
- Irradiation can be an alternative pretreatment for recalcitrant pollutants.

Triclosan is an antimicrobial agent which has been frequently detected in the environment. In this paper, the biodegradation of triclosan after radiation-induced advanced oxidation was investigated. The results show that the removal efficiency of triclosan in the combined irradiation and biological treatment process ranged from 88% to 97%, depending on the absorbed dose, while it was only 54% in the single biological treatment process. The removal efficiency of total organic carbon (TOC) was in the range of 53.1%,−59.2% at dose of 1-5 kGy in the combined irradiation and biological treatment process. In comparison, the removal efficiency of TOC in the single biological treatment process was 24.5%, suggesting that irradiation can enhance the mineralization of triclosan. The dechlorination efficiency of triclosan ranged from 48.6% to 78.4% at dose of 1-5 kGy. The intermediates of triclosan degradation were tentatively identified by LC-MS analysis and the possible degradation pathway was proposed. Based on the above results, the combined irradiation and biological treatment process could be an alternative process for treating triclosan-containing wastewater.