Transformation of dissolved organic matter during full-scale treatment of integrated chemical wastewater: Molecular composition correlated with spectral indexes and acute toxicity

Bingliang Zhang; Chao Shan; Zhineng Hao; Jingfu Liu; Bing Wu; Bingcai Pan

doi:10.1016/j.watres.2019.04.002

Transformation of dissolved organic matter during full-scale treatment of integrated chemical wastewater: Molecular composition correlated with spectral indexes and acute toxicity

Water Res. 2019 Jun 15:157:472-482. doi: 10.1016/j.watres.2019.04.002. Epub 2019 Apr 5.

Authors

Bingliang Zhang¹, Chao Shan², Zhineng Hao³, Jingfu Liu³, Bing Wu¹, Bingcai Pan⁴

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
² State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China.
³ State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
⁴ State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China. Electronic address: bcpan@nju.edu.cn.

PMID: 30981978
DOI: 10.1016/j.watres.2019.04.002

Abstract

As one of the key economic modes in China, chemical industry park (CIP) has made great contribution to the Chinese rapid economic growth. Concomitantly, how to effectively and safely dispose of the CIP wastewater (CIPWW) has been an unavoidable issue. Molecular transformation of dissolved organic matter (DOM) in CIPWW treatment is essential to optimize the employed process and to provide solid basis for risk evaluation of the discharged effluent as well. In this study, electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to characterize the molecular transformation of DOM during full-scale treatment of integrated chemical wastewater in a centralized wastewater treatment plant (CWWTP), where the combined process follows hydrolysis/acidification (HA)-flocculation/precipitation (FP)-A²/O-membrane bioreactor (MBR)-ultrafiltration (UF)-reverse osmosis (RO). Compared to municipal wastewater, DOM in CIPWW exhibited higher unsaturation degree, lower molecular weight, and higher toxicity. In FP unit, DOM of C_<24 and higher nominal oxidation state of carbon (NOSC) values was preferentially removed. The HA and anaerobic units are capable of significantly degrading DOM, resulting in great changes in molecular composition of DOM. However, the anoxic, oxic, and MBR units only lead to a slight change of the molecular formulae. The terminal units of UF and RO can remove most DOM, with the concentration of dissolved organic carbon (DOC) declining by 19.2% and 94.6% respectively. The correlation between spectral indexes and acute toxicity with the molecular formulae of DOM suggested that polyphenols and highly unsaturated phenols were positively correlated with the specific UV absorbance at 254 nm (SUVA₂₅₄). In addition, both compounds (0.32 < O/C < 0.63) as well as the aliphatic ones (0.22 < O/C < 0.56) presented positive correlation with acute toxicity. Further, the pairwise correlation analysis illustrated that SUVA₂₅₄, O/C_wa, double bond equivalence (DBE_wa), and NOSC_wa were positively correlated with each other, whereas the acute toxicity was positively correlated with humification index (HIX), O/C_wa, and DBE_wa.

Keywords: Acute toxicity; Chinese chemical industry park; Dissolved organic matter; FT-ICR-MS; Spectral indexes; Wastewater.

MeSH terms

China
Filtration
Mass Spectrometry
Ultrafiltration*
Wastewater*

Substances

Waste Water