title: Mixing regime as a key factor to determine DON formation in drinking water biological treatment.
abstract: Dissolved organic nitrogen (DON) can act as precursor of nitrogenous disinfection by-products formed during chlorination disinfection. The performances of biological fluidized bed (continuous stirred tank reactor, CSTR) and bio-ceramic filters (plug flow reactor, PFR) were compared in this study to investigate the influence of mixing regime on DON formation in drinking water treatment. In the shared influent, DON ranged from 0.71mgL(-1) to 1.20mgL(-1). The two biological fluidized bed reactors, named BFB1 (mechanical stirring) and BFB2 (air agitation), contained 0.12 and 0.19mgL(-1) DON in their effluents, respectively. Meanwhile, the bio-ceramic reactors, labeled as BCF1 (no aeration) and BCF2 (with aeration), had 1.02 and 0.81mgL(-1) DON in their effluents, respectively. Comparative results showed that the CSTR mixing regime significantly reduced DON formation. This particular reduction was further investigated in this study. The viable/total microbial biomass was determined with propidium monoazide quantitative polymerase chain reaction (PMA-qPCR) and qPCR, respectively. The results of the investigation demonstrated that the microbes in BFB2 had higher viability than those in BCF2. The viable bacteria decreased more sharply than the total bacteria along the media depth in BCF2, and DON in BCF2 accumulated in the deeper media. These phenomena suggested that mixing regime determined DON formation by influencing the distribution of viable, total biomass, and ratio of viable biomass to total biomass.
authors.affiliation: School of Civil Engineering, HeFei University of Technology, 193 Tunxi Road, Hefei 230009, China.
authors.forename: Changqing
authors.initials: C
authors.lastname: Lu
authors.affiliation: Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Li
authors.affiliation: Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China.
authors.forename: Song
authors.initials: S
authors.lastname: Gong
authors.affiliation: School of Civil Engineering, HeFei University of Technology, 193 Tunxi Road, Hefei 230009, China. Electronic address: sjyuan@hfut.edu.cn.
authors.forename: Shoujun
authors.initials: S
authors.lastname: Yuan
authors.affiliation: Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China. Electronic address: xyu@iue.ac.cn.
authors.forename: Xin
authors.initials: X
authors.lastname: Yu
mesh_terms: D018533:Biomass; D002516:Ceramics / Q000737:chemistry; D004203:Disinfection; D060766:Drinking Water / Q000737:chemistry* / Q000382:microbiology; D054879:Halogenation; D009584:Nitrogen / Q000032:analysis* / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D060766:Drinking Water; D009584:Nitrogen
keywords: Bio-ceramic filter; Biological fluidized bed; Dissolved organic nitrogen; Drinking water; PMA-qPCR