title: Inhibition of total oxygen uptake by silica nanoparticles in activated sludge.
abstract: Nanoparticle toxicity to biological activities in activated sludge is largely unknown. Among the widely used nanoparticles, silica nanoparticles (SNP) have a limited number of studies associated with inhibition to the activated sludge process (ASP). We demonstrated SNP inhibition of activated sludge respiration through oxygen uptake rate (OUR) measurement. Based on the percentage inhibition of total oxygen consumption (IT), we observed that smaller SNPs (12 nm, IT=33 ± 3%; 151 nm, IT=23 ± 2%) were stronger inhibitors than larger SNPs (442 and 683 nm, IT=5 ± 1%). Transmission electron micrographs showed that some of the SNPs were adsorbed on and/or apparently embedded somewhere in the microbial cell membrane. Whether SNPs are directly associated with the inhibition of total oxygen uptake warrants further studies. However, it is clear that SNPs statistically significantly altered the composition of microbial membrane lipids, which was more clearly described by principal component analysis and weighted Euclidian distance (PCA-ED) of the fatty acid methyl ester (FAME) data. This study suggests that SNPs potentially affect the biological activity in activated sludge through the inhibition of total oxygen uptake.
authors.affiliation: Department of Environment and Energy, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Republic of Korea.
authors.forename: Mark
authors.initials: M
authors.lastname: Sibag
authors.affiliation: School of Civil, Environmental & Architectural Engineering, Korea University, 145, Anam-ro, Sungbuk-ku, Seoul 136-701, Republic of Korea.
authors.forename: Byeong-Gyu
authors.initials: BG
authors.lastname: Choi
authors.affiliation: Energy Lab, Environment Group, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803, Republic of Korea.
authors.forename: Changwon
authors.initials: C
authors.lastname: Suh
authors.affiliation: Department of Environmental Engineering & Program in Environmental Technology and Policy, Korea University, Sejong 339-700, Republic of Korea.
authors.forename: Kwan Hyung
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Environmental Engineering & Program in Environmental Technology and Policy, Korea University, Sejong 339-700, Republic of Korea.
authors.forename: Jae Woo
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Republic of Korea.
authors.forename: Sung Kyu
authors.initials: SK
authors.lastname: Maeng
authors.affiliation: Department of Environment and Energy, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Republic of Korea. Electronic address: jinwoocho@sejong.edu.
authors.forename: Jinwoo
authors.initials: J
authors.lastname: Cho
mesh_terms: D001419:Bacteria / Q000378:metabolism; D019149:Bioreactors; D005227:Fatty Acids / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles; D010100:Oxygen / Q000032:analysis*; D025341:Principal Component Analysis; D012722:Sewage / Q000737:chemistry*; D012822:Silicon Dioxide; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D005227:Fatty Acids; D012722:Sewage; D012822:Silicon Dioxide; D010100:Oxygen
keywords: Activated sludge; Inhibition; Oxygen uptake rate; Silica nanoparticle; Wastewater treatment