Removal and degradation of diclofenac by Arundo donax L. and Streptomyces rochei

Efficient removal of pharmaceuticals (PhCs) from wastewaters before discharge into the environment is a key environmental topic. The applicability of aquatic plant-based technologies such as constructed wetlands (CWs) for the uptake and degradation of PhCs has been increasingly explored. In these systems, complex physical, chemical and biological process may simultaneously occur, including plant uptake and accumulation as well as microbial degradation. Although several studies reported significant removal of pharmaceuticals in CWs, data on the removal efficiency of microorganisms and on the direct uptake and removal of pharmaceuticals by plants are still restricted to few compounds and plant species. This study was focused on the removal of the diclofenac (DCF), a nonsteroidal anti-inflammatory drug widely found in the aquatic environment, from water by the bacteria Streptomyces rochei and the common reed Arundo donax L.. All the experiment were conducted in order to avoid photodegradation of DCF. We investigated the ability of Streptomyces rochei to degrade DCF in media under controlled conditions. Results showed a degradation of 10% in 46 h at the lowest tested concentration (1 mg L-1), with a positive correlation between the percentage of DCF degradation and both the initial concentration of DCF in the media and the time of sampling. We evaluated the growth of the plant and DCF-uptake in the common reed during 18 days of exposure at 1 and 7.4 mg L-1 of DCF in hydroponic conditions. Results showed that plants can survive to the lowest concentration of DCF with no signs of injuries, whereas the higher concentration showed initial toxicity symptoms on plants. DCF was taken up by plant and mainly accumulated in the roots (80 – 93%) with a relatively slow translocation to shoots due to DCF high hydrophobicity