Removal of artificial sweeteners in wastewater treatment plants and their degradation during sewage sludge composting with micro- and nano-sized kaolin

This study surveyed the fates of artificial sweeteners in influent, effluent, and sewage sludge (SS)via the wastewater treatment process, and investigated the effects of Micro-Kaolin treatment (Micro-KL) and Nano-Kaolin treatment (Nano-KL) on nitrogen transformation and sucralose (SUC) and acesulfame (ACE) degradation during the SS composting. The results showed the average concentrations of ACE and SUC in the influent were 1637 and 1896 ng/L, and reduced to 298 and 267 ng/L in the effluent, achieving removal rates of 82.0% and 85.9%, respectively. However, the cumulative rate of ACE and SUC in SS was ~76%. During SScomposting, kaolin reduced NH3 emissions by 30.2-45.38%, and N2O emissions by 38.4-38.9%, while the Micro-KL and Nano-KL reduced nitrogen losses by 14.8% and 12.5%, respectively. Throughout the composting process, Micro-KL and Nano-KL increased ACE degradation by 76.8% and 84.2%, and SUC degradation by 75.3% and 77.7%, and significantly shifted microbial community structure. Furthermore, the addition of kaolin caused a positive association between Actinobacteria and sweetener degradation. Taken together, the addition of kaolin effectively inhibited nitrogen loss and promoted the degradation of ACE and SUC during the SS composting, which is of great significance for the removal of emerging organic pollutants in SS.