Comparative assessment of diclofenac removal from water by different microalgae strains

Diclofenac has recently been included in the first watch list of substances to be monitored in all member states so as to evaluate its future inclusion in the priority substances list by the Water Framework Directive. Therefore, in view of upcoming limitations on diclofenac discharge, the objective of this work was to assess its removal from water by a microalgae-based treatment. Moreover, considering microalgae application inwastewater treatment, it was aimed to verify if their nutrient removal capacity was affected by the presence of diclofenac. For a comparison purpose, three different microalgae strains, namely Chlorella sorokiniana, Chlorella vulgaris and Scenedesmus obliquus, were cultured in photobioreactors under identical controlled conditions. For the three strains, the addition of diclofenac meant an organic carbon source and provided higher biomass concentration. C. sorokiniana was the strain showing the largest increase of growth rate and microalgae density, which were above 25% and 31%, respectively, compared with the positive control. However, S. obliquus showed the highest efficiency in the removal of diclofenac (>79%) and nutrients (>87% nitrates, >99% phosphates) per litre and per gram of biomass. These results pointed to the potential application of microalgae for the removal of pharmaceuticals in the bioremediation of wastewater. (C) 2016 Elsevier B.V. All rights reserved.