title: Effect of different molecular weight organic components on the increase of microbial growth potential of secondary effluent by ozonation.
abstract: Ozonation has been widely applied in advanced wastewater treatment. In this study, the effect of ozonation on assimilable organic carbon (AOC) levels in secondary effluents was investigated, and AOC variation of different molecular weight (MW) organic components was analyzed. Although the removal efficiencies were 47%-76% and 94%-100% for UV254 and color at ozone dosage of 10mg/L, dissolved organic carbon (DOC) in secondary effluents was hardly removed by ozonation. The AOC levels increased by 70%-780% at an ozone dosage range of 1-10mg/L. AOC increased significantly in the instantaneous ozone demand phase, and the increase in AOC was correlated to the decrease in UV254 during ozonation. The results of MW distribution showed that, ozonation led to the transformation of larger molecules into smaller ones, but the increase in low MW (<1kDa) fraction did not contribute much to AOC production. The change of high MW (>100kDa and 10-100kDa) fractions itself during ozonation was the main reason for the increase of AOC levels. Furthermore, the oxidation of organic matters with high MWs (>100kDa and 10-100kDa) resulted in more AOC production than those with low MWs (1-10kDa and <1kDa). The results indicated that removing large molecules in secondary effluents could limit the increase of AOC during ozonation.
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: zhaox04@mails.tsinghua.edu.cn.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Microorganism Application and Risk Control, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China. Electronic address: hyhu@tsinghua.edu.cn.
authors.forename: Hong-Ying
authors.initials: HY
authors.lastname: Hu
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Yu
authors.affiliation: College of Environment and Resources, Inner Mongolia University, Huhhot 010021, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Su
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Haochi
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Shuming
authors.initials: S
authors.lastname: Liu
mesh_terms: D064307:Microbiota / Q000187:drug effects*; D008970:Molecular Weight; D009930:Organic Chemicals / Q000737:chemistry / Q000494:pharmacology*; D010126:Ozone / Q000737:chemistry*
chemical_list: D009930:Organic Chemicals; D010126:Ozone
keywords: Assimilable organic carbon (AOC); Biological stability; Molecular weight distribution; Ozonation; Wastewater reclamation and reuse