title: Leaching of polycyclic aromatic hydrocarbons (PAHs) from industrial wastewater sludge by ultrasonic treatment.
abstract: Ultrasonic treatment for sludge reduction in wastewater treatment plants (WWTPs) can substantially affect the fate of trace pollutants. However, their fates in the different phases of sludge and mass balances have rarely been reported. In this study, wastewater sludge samples were ultrasonicated at 600W for 0-30min. Then, the leaching of the 16 priority polycyclic aromatic hydrocarbons (PAHs) from the sludge solids (sediment) to the liquid phase (supernatant) was investigated. The total concentration of PAHs (∑16 PAHs) in the sludge sediment (2.10μg/g) was comparable with those of previous worldwide studies. Among the 16 PAHs, naphthalene and acenaphthylene were dominant. The total concentrations of PAHs in the supernatant generally increased with sonication time, indicating that PAHs associated with sludge materials, such as microorganisms, were released into the supernatant. Lighter and more water soluble PAHs were released preferentially into the supernatant in dissolved form, whereas heavier and more hydrophobic PAHs were strongly bound to particles. According to mass balance calculations, 21% of the PAHs in the sludge sediment moved to the supernatant without discernible sonodegradation. An additional experiment for degradation of PAHs supported this interpretation, and several reasons for the no significant sonodegradation were discussed. This result suggests that leaching trace pollutants may significantly contaminate the sludge filtrate after ultrasonic treatment, and therefore their fates should be investigated.
authors.affiliation: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
authors.forename: Joo-Yeon
authors.initials: JY
authors.lastname: Oh
authors.affiliation: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea. Electronic address: sdchoi@unist.ac.kr.
authors.forename: Sung-Deuk
authors.initials: SD
authors.lastname: Choi
authors.affiliation: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
authors.forename: Hye-Ok
authors.initials: HO
authors.lastname: Kwon
authors.affiliation: School of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea.
authors.forename: Sung-Eun
authors.initials: SE
authors.lastname: Lee
mesh_terms: D007221:Industry; D011084:Polycyclic Aromatic Hydrocarbons; D012722:Sewage; D014465:Ultrasonics; D062065:Wastewater; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Leaching; PAHs; Sludge; Sonication; Ultrasonic treatment