Kim, Jihee Licto, Ana Gabriela Chuquer Cho, Kyungjin Kim, Eun-Ju 2025-04-09T08:00:06Z 2025-04-09T08:00:06Z 2025-04-09 2025-07 0304-3894 https://pubs.kist.re.kr/handle/201004/152195 Microplastics (MPs) entering wastewater treatment plants accumulate in sludge and are subsequently introduced into anaerobic digesters, a key sludge treatment process. However, little is known about how MPs undergo transformation during anaerobic digestion (AD). This study investigated the mechanism underlying the aging of polystyrene (PS) MPs in AD and its effect on heavy metal adsorption. In the AD batches containing an initial sulfate concentration of 5.1 mM, significant sulfate reduction (96.1 %) was observed, with reduced sulfur species accounting for 74 % of the total sulfur species deposited on the PS surface, as revealed by X-ray photoelectron spectroscopy. A positive correlation between sulfide formation and the selective proliferation of sulfur-reducing bacteria, particularly Desulfovibrio aminophilus, indicated the involvement of microorganisms in sulfur aging. The decomposition of in situ hydrogen peroxide (H2O2) and formation of hydroxyl radicals (center dot OH) under sulfidogenic conditions were more pronounced, suggesting that reactive oxygen species may induce structural changes in PS MPs and potentially facilitate sulfur aging. Finally, isothermal titration calorimetry results showed that sulfur- aged PS had higher binding constants for Pb2* and Cu2* compared to pristine PS, due to the presence of sulfur-containing functional groups and a more negative surface charge. These findings provide valuable insights into the fate of MPs during the sludge treatment and their potential environmental impacts. English Elsevier BV In situ formed sulfide-mediated aging of polystyrene microplastics and its impact on the fate of heavy metals in anaerobic digestion Article 10.1016/j.jhazmat.2025.137995 1 Journal of Hazardous Materials, v.491 Journal of Hazardous Materials 491 N scie scopus 001455849900001 2-s2.0-105000487649 Engineering, Environmental Environmental Sciences Engineering Environmental Sciences & Ecology Article SULFATE REDUCTION OXIDATION PRODUCTS OXYGEN Anaerobic digestion Sulfate-reducing bacteria Sulfur aging Reactive oxygen species Polystyrene microplastics