Molecular insight into variations of dissolved organic matters in leachates along China's largest A/O-MBR-NF process to improve the removal efficiency. (March 2020)

• Record Type: Journal Article
• Authors: Wang, Hui; Cheng, Zhaowen; Sun, Zhiyi; Zhu, Nanwen; Yuan, Haiping; Lou, Ziyang; Chen, Xiaoliang
• Is Part Of: Chemosphere. Volume 243(2020)
• Publication Date: 2020-03
• Subjects: Landfill leachate -- Dissolved organic matter -- Molecular characterization -- ESI FT-ICR MS -- Organosulfur compounds; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.125354
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Dissolved organic matter (DOM) is a critical component of high-strength organic wastewater, and the study of them from molecular perspective could improve the removal efficiency. Leachate samples were collected from China's largest two stage anaerobic/aerobic membrane bioreactor and nanofiltration (A/O-MBR-NF) process, with the treatment capacity of 5000 t/d, and characterized by electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) from molecular perspective. High molecular weight ( m / z > 500) compounds with 40–50 carbon atoms and 15–20 double bond equivalence (DBE) were biodegraded into medium molecular weight compounds with 10–20 carbon atoms and ∼10 DBE. Contribution of lipids and unsaturated hydrocarbons compounds in DOM turned into 42.1% and 2.5%, respectively, while contribution of condensed aromatics in DOM dramatically increased to 15.4% in leachates along the A/O-MBR process. Most of DOM was converted into higher polymerization degree and accumulated in concentrated leachate (CL). Sulfur-containing compounds, whose relative peak ratio accounted for 56.4%, were regarded as recalcitrant DOM in CL. Increase of retention time in anaerobic unit for raw leachate might be useful for decomposing the long-chain organic compounds, which could also reduce loadings for the following A/O-MBR process. Well-focus techniques such as sulfur-oxidation bacteria could be introduced into the MBR unit for better removing organo-sulfur compounds. Advanced oxidation processes for CL degradation would be efficiency for the removal of recalcitrant DOM. Thus, leachate could be disposed in a zero-discharge way based on the practical experience of such a typical working treatment process. Graphical abstract: Image 1 Highlights: Molecular level of dissolved organic matters (DOM) in leachate samples were investigated. ESI FT-ICR MS was firstly employed to evaluate DOM variation in leachate combined with UV/vis and EEM. A large-scale leachate treatment with typical A/O-MBR-NF processes were investigated. A total of 191 class species of recalcitrant DOM were firstly identified in concentrated leachate. Well-focus techniques were proposed for leachate zero-discharge.