No abstract

Emerging microcontaminants benzophenone (BP), benzophenone-3 (BP-3) and caffeine (CF) are widely used anthropogenic markers from a group of pharmaceuticals and personal care products. They have different logD values and charges at neutral pH (2.96 neutral for BP; 3.65 negative and neutral for BP-3; 0.28 and neutral for CF). The goal of this study was to assess the efficacy of coagulation/flocculation/sedimentation (C/F/S), adsorption onto two types of powdered activated carbon (PAC)/sedimentation (PAC/S) and the combination of these two processes in different dosing sequences (PAC/C/F/S) and with/without ultrafiltration (powdered activated carbon/ultrafiltration—PAC/UF, coagulation/UF—CoA/UF) for the removal of selected micropollutants from river water. It was shown that the removal efficiency of benzophenones by coagulation depends on the season, while CF was moderately removed (40–70%). The removal of neutral BP by two PACs unexpectedly differed (near 40% and ˃93%), while the removal of BP-3 was excellent (>95%). PACs were not efficient for the removal of hydrophilic CF. Combined PAC/C/F/S yielded excellent removal for BP and BP-3 regardless of PAC type only when the PAC addition was followed by C/F/S, while C/F/S efficiency for CF diminished. The combination of UF with PAC or coagulant showed also high efficacy for benzophenones, but was negligible for CF removal.

In this study, hybrid ultrafiltration which involves adsorption onto activated carbon and/or coagulation was tested for the removal of ibuprofen, caffeine and diclofenac from the municipal wastewater treatment plant effluent (c0 = 2–3 µg/L). Ultrafiltration was tested in combination with powdered activated carbon dose of 5 mg/L separately or with coagulants (FeCl3, dose 4 mg Fe (III)/L and, natural coagulant isolated from bean seeds, dose 33 µL/L). In addition to the removal of organic micropollutants, the removal of As, Cr, Cu and Zn was also tested (c0~100 µg/L). The research was conducted on a laboratory pilot plant (capacity 30 L/h, in-out dead-end filtration, flux of 80 L/m2h). The best results were obtained for caffeine when adsorption on PAC is combined with a FeCl3 (removal efficiency 42–87%). The addition of a natural coagulant did not show benefits for the removal of organic micropollutants compared to the other tested processes, but both coagulants had similar effects on the content of metals and As Hybrid membrane processes proved to be the most efficient for Zn (44–87%) and Cr (33–87%) removal. The lowest efficiency was determined for As (˂19%). Ultrafiltration with PAC and coagulants removed 5–33% of effluent organic matter, depending on the type of coagulant; 57–87% of total nitrogen and PAC/FeCl3/UF was also partially effective for removing total phosphorus (11–39%).