Enhanced removal of pharmaceutical compounds and organic matter from drinking water and wastewater by novel and sustainable activated carbons

Abstract

Water treatment improvement is mandatory to face current water quality challenges, being a focus of the United Nations’ 2030 sustainable development goals. Activated carbon (AC) adsorption is one of the best available technologies to control pharmaceutical compounds (PhCs) in water. In this work, we developed renewable source derived powdered ACs (PACs), which were tested for the control of PhCs and natural organic matter in conventional urban wastewater treatment (UWWT) and in drinking water treatment (DWT) plants. Lab-made PACs were synthetized from food industry by-products (i.e., carob processing waste, pine cones and pine nut shells (PNS)) an tested in operational environment, i.e. under competitive adsorption of three PhCs (carbamazepine, diclofenac and sulfamethoxazole) spiked in effluents from UWWT plants and in a pre-oxidized water from a DWT plant with source water quality challenges (i.e. high organic matter content). For both applications, PNS-derived PACs obtained by steam or CO2 activation outperformed commercial counterparts for the removal of the three target PhCs (spiked in the tested waters) and the water background organic matter. Advanced data modelling allowed estimating the PAC dose for a given overall removal of the target-PhCs in UWWT. A multivariate analysis, involving water, PhC and PAC related descriptors, show that hydrophobic PhC-PAC interactions play the major role in the adsorption process (i.e. solvation energy and log Kow). For the PACs tested, the results point the BET area as a good descriptor of the PAC capacity, while the short-term adsorption kinetics appears to be better related to supermicropore volume and density.