Designing renewable-source derived activated carbons for the adsorption of pharmaceutical compounds from urban wastewater

Abstract

The removal of pharmaceutical compounds (PhCs) from water has numerous challenges mainly associated with their low concentration and varied nature and physicalo-chemical properties. Activated carbon adsorption and ozonation are considered consolidated technologies, with confirmed cost-efficient elimination of organic microcontaminants and toxicity in several full-scale wastewater treatment plants (WWTPs), namely in Switzerland and in Germany. Several biomass precursors, activation agents, and routes were explored at lab-scale (including cork processing by-products and carob processing acid residues pinpointing pine nut shell (PNS) as the most promising raw material: PAC steam activated sample PNS77/Steam performed similarly to the commercial golden standards (from Cabot-Norit and Chemviron). PNS-derived PAC production was scaled-up using CO2 activation and results prove that, for similar burn-off degrees, steam and CO2 activation attain similar and excellent textural properties. PACs were tested in WWTP mixed liquor and secondary effluent. Data modelling (HSDM – Freundlich isotherm) allowed estimating the PAC dose to the CAS bioreactor required for a given overall removal of the target-PhCs. Currently, EMPOWER+ project builds on the promising PNS-derived PACs, is focused on testing their performance for drinking water treatment (DWT) in both conventional and advanced treatment (adsorption/low-pressure membrane) technologies. Preliminary data prove that these lab-made materials also attain a high performance in this high- value application.