Effect mechanism of biological aerated filter on disinfection byproducts and their precursors
Disinfection has become an indispensable part of water treatment systems,but dissolved organic matter(DOM)in water inevitably produces toxic and harmful disinfection by-products(DBPs)when reac-ting with disinfectants,thereby affecting the safety of drinking water.To explore the influence of biological aerated filter(BAF)on the removal of dissolved organic matter(DOM)and the generation of disinfection byproducts(DBPs),we used Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)combined with optical spectrum technology and chromatography-mass spectrometry to comprehensively in-vestigate the effect of BAF on DBPs and their precursors,and the formation pathways of DBPs were clari-fied through mass difference network analysis.The results show that BAF partially removes the aromatic proteins in the influent,and reduces the concentrations of trihalomethanes,haloacetic acids and haloacetoni-triles produced after disinfection,but increases the concentrations of halonitromethanes.These conventional DBPs account for less than 60%of the total organic chloride concentration.At the molecular level,BAF tends to convert molecules with a low oxidation degree and high saturation into molecules with a high oxi-dation degree and high unsaturation,resulting in less DBPs with low unsaturation and more DBPs with high unsaturation during subsequent chlorination,which may facilitate the removal of DBPs and their precursors in the subsequent coagulation and sedimentation unit of the water plant.Mass difference network analysis shows that chlorine substitution(+Cl—H),chlorine addition(+HClO)and hydroxylation and chlorine substitution(+ClO—H)are the dominant pathways to generate DBPs,and the unsaturation of DBPs pre-cursors participating in addition reaction is higher than that of the precursors participating in substitution reaction.This study can provide basic information for the DBPs control of drinking water.
biological aerated filter(BAF)dissolved organic matter(DOM)disinfection by-products(DB-Ps)FT-ICR MS