The proliferation and possible adverse effects of emerging contaminants such as pharmaceutical and personal care products (PPCPs) in waters and the environment is causing increased concern. We investigated the dissipation of three PPCPs: ibuprofen (IBP), diclofenac (DCF) and triclosan (TCS), separately or in mixture, in the ppm range in microcosm biopurification systems (BPS), paying special attention to their effect on bacterial ecotoxicity and on bacterial community structure and composition. The results reveal that the BPS efficiently dissipates IBP and DCF with 90% removal after 45 and 84 days of incubation, respectively. However, removal of TCS required longer incubation, 127 days for 90% removal. Furthermore, dissipation of the three PPCPs was slower when all three were applied to the BPS as a mixture. TCS had an initial negative effect on bacterial viability by a decrease of 34-43%; however, this effect was mitigated when all three PPCPs were present simultaneously. The bacterial communities in the BPS were affected much more by incubation time than by the applied PPCPs.Nonetheless, the PPCPs affected differentially the composition and relative abundance of bacterial taxa. IBP and DCF initially increased bacterial diversity and richness while exposure to TCS generally provoked the opposite effect. TCS had the largest effect on bacterial groups negatively affecting the relative abundance of Acidobacteria, Rickettsiales, Methylophilales, Methylacidiphilae and Phycisphaerae. On the other hand, all three PPCPs stimulated the dominant bacterial families Promicromonosporaceae, Caulobacteraceae, Xanthomonadaceae, Cyclobacteriaceae, Sphingobacteriaceae and Verrucomicrobiaceae, whose members could harbour mechanisms for resistance by degradation and/or detoxification.

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