title: How UV photolysis accelerates the biodegradation and mineralization of sulfadiazine (SD).
abstract: Sulfadiazine (SD), one of broad-spectrum antibiotics, exhibits limited biodegradation in wastewater treatment due to its chemical structure, which requires initial mono-oxygenation reactions to initiate its biodegradation. Intimately coupling UV photolysis with biodegradation, realized with the internal loop photobiodegradation reactor, accelerated SD biodegradation and mineralization by 35 and 71 %, respectively. The main organic products from photolysis were 2-aminopyrimidine (2-AP), p-aminobenzenesulfonic acid (ABS), and aniline (An), and an SD-photolysis pathway could be identified using C, N, and S balances. Adding An or ABS (but not 2-AP) into the SD solution during biodegradation experiments (no UV photolysis) gave SD removal and mineralization rates similar to intimately coupled photolysis and biodegradation. An SD biodegradation pathway, based on a diverse set of the experimental results, explains how the mineralization of ABS and An (but not 2-AP) provided internal electron carriers that accelerated the initial mono-oxygenation reactions of SD biodegradation. Thus, multiple lines of evidence support that the mechanism by which intimately coupled photolysis and biodegradation accelerated SD removal and mineralization was through producing co-substrates whose oxidation produced electron equivalents that stimulated the initial mono-oxygenation reactions for SD biodegradation.
authors.affiliation: Department of Environmental Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai, 200234, People's Republic of China.
authors.forename: Shihui
authors.initials: S
authors.lastname: Pan
authors.forename: Ning
authors.initials: N
authors.lastname: Yan
authors.forename: Xinyue
authors.initials: X
authors.lastname: Liu
authors.forename: Wenbing
authors.initials: W
authors.lastname: Wang
authors.forename: Yongming
authors.initials: Y
authors.lastname: Zhang
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Rittmann
mesh_terms: D001673:Biodegradation, Environmental; D010782:Photolysis; D013411:Sulfadiazine / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D013411:Sulfadiazine