Evaluation of five filter media in column experiment on the removal of selected organic micropollutants and phosphorus from household wastewater.

A bench-scale column experiment was performed to study the removal of 31 selected organic micropollutants (MPs) and phosphorus by lignite, xyloid lignite (Xylit), granular activated carbon (GAC), Polonite® and sand over a period of 12 weeks. In total 29 out of the 31 MPs showed removal efficiency >90% by GAC with an average removal of 97 ±â€¯6%. Xylit and lignite were less efficient with an average removal of 80 ±â€¯28% and 68 ±â€¯29%, respectively. The removal efficiency was found to be impacted by the characterization of the sorbents and physicochemical properties of the compounds, as well as the interaction between the sorbents and compounds. For instance, Xylit and lignite performed well for relatively hydrophobic (log octanol/water partition coefficient (Kow) ≥3) MPs, while the removal efficiency of moderately hydrophilic, highly hydrophilic and negatively charged MPs were lower. The organic sorbents were found to have more functional groups at their surfaces, which might explain the higher adsorption of MPs to these sorbents. The removal of several MPs improved after four weeks in sand, Xylit, GAC and lignite which may be related to increased biological activity and biofilm development. GAC and sand had limited ability to remove phosphorus (12 ±â€¯27% and 14 ±â€¯2%, respectively), while the calcium-silicate material Polonite® precipitated phosphorus efficiently and increased the total phosphorus removal from 12% to 96% after the GAC filter.

Removal of pharmaceuticals, perfluoroalkyl substances and other micropollutants from wastewater using lignite, Xylit, sand, granular activated carbon (GAC) and GAC+Polonite® in column tests - Role of physicochemical properties.

This study evaluated the performance of five different sorbents (granular activated carbon (GAC), GAC + Polonite® (GAC + P), Xylit, lignite and sand) for a set of 83 micropollutants (MPs) (pharmaceuticals, perfluoroalkyl substances (PFASs), personal care products, artificial sweeteners, parabens, pesticide, stimulants), together representing a wide range of physicochemical properties. Treatment with GAC and GAC + P provided the highest removal efficiencies, with average values above 97%. Removal rates were generally lower for Xylit (on average 74%) and lignite (on average 68%), although they proved to be highly efficient for a few individual MPs. The average removal efficiency for sand was only 47%. It was observed that the MPs behaved differently depending on their physicochemical properties. The physicochemical properties of PFASs (i.e. molecular weight, topological molecular surface area, log octanol water partition coefficient (Kow) and distribution coefficient between octanol and water (log D)) were positively correlated to observed removal efficiency for the sorbents Xylit, lignite and sand (p < 0.05), indicating a strong influence of perfluorocarbon chain length and associated hydrophobic characteristics. In contrast, for the other MPs the ratio between apolar and polar surface area (SA/SP) was positively correlated with the removal efficiency, indicating that hydrophobic adsorption may be a key feature of their sorption mechanisms. GAC showed to be the most promising filter medium to improve the removal of MPs in on-site sewage treatment facilities. However, more studies are needed to evaluate the removal of MPs in field trials.