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Nonhalogenated Aromatic DBPs in Drinking Water Chlorination: A Gap between NOM and Halogenated Aromatic DBPs
Jingyi Jiang1, Jiarui Han1, Xiangru Zhang1
1Department of Civil and Environmental Engineering , Hong Kong University of Science and Technology , Hong Kong 999077 , China.
Environmental Science & Technology
|January 8, 2020
Summary
Researchers identified nine new nonhalogenated aromatic compounds as intermediate disinfection byproducts (DBPs) during drinking water chlorination. These compounds bridge the gap between natural organic matter and toxic halogenated DBPs, and can be removed by granular activated carbon.
Area of Science:
- Environmental Chemistry
- Water Treatment
- Organic Chemistry
Background:
- Chlorination of drinking water produces halogenated disinfection byproducts (DBPs) from natural organic matter (NOM).
- The transformation pathways from large NOM molecules to halogenated aliphatic DBPs are not fully understood.
- Previously identified halogenated aromatic DBPs are thought to be intermediates that decompose into halogenated aliphatic DBPs.
Purpose of the Study:
- To identify and characterize new intermediate disinfection byproducts formed during drinking water chlorination.
- To investigate the formation pathways and kinetics of these novel intermediate DBPs.
- To assess the role of these intermediates in the overall DBP formation process and their removal potential.
Main Methods:
- Identification of nine nonhalogenated aromatic compounds as novel intermediate DBPs using analytical techniques.
- Proposal of formation pathways for these nonhalogenated aromatic DBPs.
- Modeling of formation kinetics for selected nonhalogenated aromatic DBPs and their chlorinated derivatives.
- Evaluation of granular activated carbon (GAC) adsorption for removing these nonhalogenated aromatic DBPs.
Main Results:
- Nine nonhalogenated aromatic compounds were identified as new intermediate DBPs during chlorination.
- These nonhalogenated aromatic DBPs formed rapidly at low chlorine doses and short contact times.
- Nonhalogenated aromatic DBPs contributed significantly to the formation of monochloro- and dichloro-substituted DBPs, acting as intermediates between NOM and halogenated aromatic DBPs.
- Granular activated carbon adsorption removed over 50% of the formed nonhalogenated aromatic DBPs.
Conclusions:
- Nonhalogenated aromatic compounds represent a crucial, previously unrecognized intermediate step in the formation of halogenated DBPs from NOM during chlorination.
- Understanding these intermediates provides a more complete picture of DBP formation pathways in drinking water.
- Granular activated carbon shows promise for removing these newly identified intermediate DBPs.
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