Photodegradation and Removal of Diclofenac by the Green Alga Nannochloropsis oculata

The emerging contaminants (ECs) are organic compounds including pharmaceuticals. These products are consumed in large quantities, favoring their continuous entrance to the environment and affecting the health of living beings. Diclofenac is a non-steroidal anti-inflammatory drug with analgesic properties of prolonged release. It is the commonest postoperative analgesic, and it is highly consumed without prescription. In recent years, the capability of microalgae to remove pharmaceuticals in water has been tested as a promising tool. In this work, the removal efficiency of diclofenac (16 mu g/mL) by the microalga Nannochloropsis oculata CCAP 186/7 was evaluated. The major nutrient concentrations in Bold's Basal Medium were modified (nitrogen and carbon: 50 and 100% of their original concentration) to know their effect in the removal of diclofenac. Drug degradation by light was also evaluated. The maximum removal capacity of diclofenac in the medium was 68.8%. The percentage of diclofenac adsorbed on the cell wall was between 6 and 12.7%. Around 23.6% of diclofenac was degraded by light after 18 days. N. oculata did not show growth inhibition due to the presence of diclofenac. The results obtained point to the promissory application of N. oculata as a bioremediation system for diclofenac removal.