TiO₂ and halloysite-modified ultrafiltration membranes for treating wastewater treatment plants effluent

The aim of this study was to determine the possibility of using polymeric ultrafiltration membranes modified with titanium dioxide and nanohalloysite nanoparticles to remove selected micropollutants from wastewater treatment plants (WWTP) effluent. Four types of membranes were used, which were prepared from polyacrylonitrile and polyethersulfone and then modified with halloysite and titanium(IV) oxide (TiO₂). The feed water was obtained by adding organic micropollutants to the effluent obtained from Gliwice's wastewater treatment plant. Due to the different properties of the organic micropollutants, the following compounds were selected for this study: benzotriazole, bisphenol A, carbamazepine, and caffeine. The treatment efficiency of the effluent spiked with selected micropollutants varied depending on the membrane polymer and the type of nanoparticles used to modify the membranes. The results showed that titanium(IV) oxide nanoparticles improved the volumetric permeate flux, which improved the transport properties of the modified membranes. Polyacrylonitrile membranes, although highly hydrophilic, were the most susceptible to fouling, regardless of the type of nanoparticle they were modified with, which may be due to their high porosity. The PES16-HNT membrane showed the highest reduction in typical quality parameters, while the PES16-TiO₂ membrane showed the highest micropollutant retention. From these results, it can be concluded that the modified ultrafiltration membranes can be used to treat WWTP effluent, which is a source of micropollutants that enter the environment.