Effects of recirculation in a three-tank pilot-scale system for pharmaceutical removal with powdered activated carbon
(English)Manuscript (preprint) (Other academic)
The removal of pharmaceutically active compounds by powdered activated carbon (PAC) in municipal wastewater is a promising solution to problem of polluted recipient waters. Today, an efficient design strategy is however lacking in particular with regard to high-level overall, but also specific, substance removal for operation in the large scale. The performance of PAC-based removal of pharmaceuticals was studied in pilot-scale with respect to the critical parameters; contact time and PAC dose using one PAC product selected by screening in bench-scale. The goal was a minimum of 95% removal of the pharmaceuticals present in the evaluated municipal wastewater. A set of 21 pharmaceuticals was selected from an initial 100 due to their high occurrence in the effluent water of two selected wastewater treatment plants (WWTPs) in Sweden, whereof candidates discussed for future EU regulation directives were included. A combination of the benefits of powdered and granular carbon performance was achieved by the recirculation of PAC over a three-tank sequential contact line, where recirculation could be introduced in any of the three tanks to investigate the importance for the adsorption performance. This was compared to use of the setup, but without recirculation. A higher degree of pharmaceutical removal was achieved in all recirculation setups, both with respect to overall and specific substances, as compared to without recirculation. Recirculation was tested with nominal contact times of 30, 60 and 120 minutes and the goal of 95% removal could be achieved already at the shortest times at a PAC dose of 10-15 mg/L. In particular the overall removal could be increased even to 97% and 99%, at 60 and 120 min, respectively, when the recirculation point was the first tank. Recirculation of PAC to either the first or the second contact tank proved to be comparable, while a slightly weaker performance was observed with introduced in the third tank. With regards to individual substances, clarithromycin and diclofenac were ubiquitously removed according to the set goal and in contrast, a few substances (fluconazole, irbesartan, memantine and venlafaxine) required specific settings to reach an acceptable removal.
Adsorption, Advanced wastewater treatment, Municipal wastewater, PAC, Pharmaceuticals, Recirculation
Research subject Biotechnology
IdentifiersURN: urn:nbn:se:kth:diva-195707OAI: oai:DiVA.org:kth-195707DiVA: diva2:1045243
FunderMistra - The Swedish Foundation for Strategic Environmental Research
QC 201611242016-11-082016-11-082016-11-24Bibliographically approved