Triclosan transformation and impact on an elemental sulfur-driven sulfidogenic process

Elemental sulfur reduction has recently been demonstrated to be a promising sulfidogenic process for cost-effective treatment of various wastewaters. However, it remains unknown if sulfur reduction is capable of pharmaceuticals and personal care products (PPCPs) removal. Thus, this study investigated the feasibility of such process to remove PPCPs and how PPCPs influence the system performance during a long-term operation. Triclosan (TCS), a typical broad-spectrum antibacterial agent and a ubiquitous emerging organic contaminant in environments was chosen as the model compound. Results showed that TCS was removed principally via fast sorption followed by slow biodegradation. Amides, polysaccharides and hydroxyl groups in extracellular polymeric substances (EPS) provided adsorption sites. Both metabolism and co-metabolism of TCS with organic carbon removal were responsible for TCS biodegradation. Reductive dechlorination and hydroxylation of TCS were inferred during TCS biodegradation. The genera Georgenia, Soehngenia, Comamonas, Pseudomonas, Desulfovibrio and Sulfurospirillum were the potential TCS degraders in the sulfur-reducing system. Additionally, the presence of TCS at environmentally relevant concentrations did not negatively impact the performance of organic carbon removal, but altered functional bacteria groups (i.e. fermentative and sulfur-reducing genera). In summary, the sulfur-reducing system could be sufficiently robust to transform organohalide antimicrobials of PPCPs (e.g. triclosan) without compromising the performance.