title: Retention of titanium dioxide nanoparticles in biological activated carbon filters for drinking water and the impact on ammonia reduction.
abstract: Given the increasing discoveries related to the eco-toxicity of titanium dioxide (TiO2) nanoparticles (NPs) in different ecosystems and with respect to public health, it is important to understand their potential effects in drinking water treatment (DWT). The effects of TiO2 NPs on ammonia reduction, ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in biological activated carbon (BAC) filters for drinking water were investigated in static and dynamic states. In the static state, both the nitrification potential and AOB were significantly inhibited by 100 μg L(-1) TiO2 NPs after 12 h (p < 0.05), and the threshold decreased to 10 μg L(-1) with prolonged exposure (36 h, p < 0.05). However, AOA were not considerably affected in any of the tested conditions (p > 0.05). In the dynamic state, different amounts of TiO2 NP pulses were injected into three pilot-scale BAC filters. The decay of TiO2 NPs in the BAC filters was very slow. Both titanium quantification and scanning electron microscope analysis confirmed the retention of TiO2 NPs in the BAC filters after 134 days of operation. Furthermore, the TiO2 NP pulses considerably reduced the performance of ammonia reduction. This study identified the retention of TiO2 NPs in BAC filters and the negative effect on the ammonia reduction, suggesting a potential threat to DWT by TiO2 NPs.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai, 200092, China.
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai, 200092, China. 8566liliu@tongji.edu.cn.|Department of Municipal Engineering, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China. 8566liliu@tongji.edu.cn.
authors.forename: Shuili
authors.identifier: 0000-0003-2773-9342
authors.initials: S
authors.lastname: Yu
authors.affiliation: School of Civil, Environmental and Architectural Engineering, Korea University, Seoul, 136-714, South Korea.
authors.forename: Heedeung
authors.initials: H
authors.lastname: Park
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai, 200092, China.
authors.forename: Guicai
authors.initials: G
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai, 200092, China.
authors.forename: Qingbin
authors.initials: Q
authors.lastname: Yuan
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000378:metabolism; D001673:Biodegradation, Environmental; D002606:Charcoal; D060766:Drinking Water / Q000032:analysis*; D005374:Filtration; D053758:Nanoparticles / Q000032:analysis*; D014025:Titanium / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water; C009495:titanium dioxide; D002606:Charcoal; D000641:Ammonia; D014025:Titanium
keywords: Ammonia-oxidizing archaea; Ammonia-oxidizing bacteria; Biological activated carbon filter; Drinking water treatment; Titanium dioxide nanoparticle