Assessment of molecularly imprinted polymers for selective removal of diclofenac from wastewater by laboratory and pilot-scale adsorption tests

This study investigated the potential of Molecularly Imprinted Polymers (MIPs) to integrate schemes for wastewater reuse and to serve as effective adsorbent for the removal of a target emerging contaminant (i.e., diclofenac – DCF), after or within pilot scale anaerobic biological treatments. Batch tests were performed to evaluate the effect on DCF removal during anaerobic biological processes by enriching activated sludge of an Upflow Anaerobic Sludge Blanket (UASB) reactor (TSS =19.6 g/L), and an Anaerobic Membrane Bioreactor (AnMBR) (TSS = 120 mg/L) reactors with MIPs (3 mg/L). Therefore, tertiary treatments were investigated by columns adsorption tests that were performed first at lab scale using DCF (15 mg/L) solution in deionized water, and then in-site by treating the anaerobic permeate effluent from the AnMBR at pilot scale level (DCF 500 μg/L). Clogging or blockage of the column bed was not observed during these field tests, where the saturation process of MIPs was slower compared to laboratory tests that used deionized water. In addition, the empirical Thomas Model, Yoon-Nelson Model, Dose-Response Model and Adam Bohart Model showed very good fittings with the experimental data obtained during experiments performed with both synthetic water and anaerobic effluents showing their suitability for the description of breakthrough curves. Finally, it was observed that after regeneration the MIPs can be efficiently reused since adsorption capacity is sufficiently preserved.