ABSTRACT
The COVID-19 pandemic has resulted in an increased use of disinfectants worldwide. One of the most popular active ingredients is triclosan (TRC), which is added to personal care products such as soap, wet wipes and dish soap. Negative aspect of TRC in wastewater is its release into the environment, since TRC is not completely removed in WWTPs. In the context of the rapidly increasing concentration of disinfectants in the wastewater influent, the aim of the study was to develop a method for treating wastewater containing TRC. Biological treatment in a sequential batch reactor (SBR) was used, and then the SBR effluent was treated in one of the tertiary processes i.e. ultrafiltration/adsorption/ozonation/ozonation+UV. In the ultrafiltration step, innovative membranes were used, such as membranes prepared from recycled polystyrene (rec-PS) or polyethersulfone mixed with single-walled carbon nanotubes (PES-SWCNT). Adsorption was conducted in fixed-bed columns packed with novel composite adsorbent containing halloysite and single-walled carbon nanotubes. TRC impaired the removal of phosphate and caused the degradation of activated sludge. Phosphate removal in the SBR-2 reactor (wastewater with TRC) decreased throughout the 6 weeks from 48.1 % to 38.1 %;in contrast, for SBR-1 (wastewater without TRC), it increased from 34.3 % to 71.8 %. The phosphate concentration of the effluent exceeded the permissible values, necessitating further treatment. Flocs from SBR-2 were smaller and looser compared to those from the control SBR. Biodegradation of TRC was noted in the 5th week of the operation as methyl TRC was detected in the effluent (0.07 mg/L). In ultrafiltration with PES-SWCNT membrane, phosphate, TRC, and methyl TRC were reduced by 33.7 %, 27.8 %, 36.8 %, respectively. On the other hand, adsorption, ozonation and ozonation+UV processes were highly suitable to treat SBR effluent. The phosphate, TRC and TRC byproducts removal degrees exceeded 90 % both for adsorption in the fixed-bed column as well as the ozonation and ozonation+UV processes.