Removal of diclofenac by filtration: experimental results and modelling

Resúmen del póster presentado en SETAC Europe 34th Annual Meeting 5-9 May 2024, Sevilla (España)

The occurrence of organic micropollutants in surface waters is of serious concern because of their ubiquity and adverse effects on humans and environment. Wastewater treatment plants are the main disposal of these pollutants into the environment due to their inefficient removal in the course of water purification. The European Union established a watch list of substances for their potential inclusion in a list of priority substances in the field of water policy, in which diclofenac (DC) was included (Decision 2015/495/EC). Recently, the new EU Directive proposal for urban wastewater treatment (2022/0345) set a list of 16 substances, including DC stayed, that classified them into three categories based on ease of their removal. The analysis of removal of DC by using bed filtration with two different adsorbents was analyzed by a model that considers convection and adsorption/desorption, which was extended by accounting for degradation during filtration. The sorbents used were a granular activated carbon (GAC) and an enzyme-based complex. The validity of the model was demonstrated. In the particular case of the enzyme-based complex, the removal of DC is initially due mostly to adsorption and hardly degradation. The model yields in parallel to the experimental results an increase of the concentration of emerging DC with time for a range of times, but the model predicts attainment of a steady state which is reached earlier in the case of a larger degradation constant and in the case of a longer filter. The analysis of the filtration data with the model enabled to determine parameters for generating predictions for other sets of operational conditions. This enables to determine the capacity of the filters for economic estimates.

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