title: Pathways of nitrobenzene degradation in horizontal subsurface flow constructed wetlands: Effect of intermittent aeration and glucose addition.
abstract: Intermittent aeration and addition of glucose were applied to horizontal subsurface flow constructed wetlands in order to investigate the effect on pathways of nitrobenzene (NB) degradation and interactions with microbial nitrogen and sulphur transformations. The experiment was carried out in three phases A, B and C consisting of different NB loading and glucose dosing. For each phase, the effect of aeration was assessed by intermittently aerating one wetland and leaving one unaerated. Regardless of whether or not the wetland was aerated, at an influent NB concentration of 140 mg/L, both wetlands significantly reduced NB to less than 2 mg/L, a reduction efficiency of 98%. However, once the influent NB concentration was increased to 280 mg/L, the aerated wetland had a higher removal performance 82% compared to that of the unaerated wetland 71%. Addition of glucose further intensified the NB removal to 95% in the aerated wetlands and 92% in the unaerated. Aeration of wetlands enhanced NB degradation, but also resulted in higher NB volatilization of 6 mg m(-2) d(-1). The detected high concentration of sulphide 20-60 mg/L in the unaerated wetland gave a strong indication that NB may act as an electron donor to sulphate-reducing bacteria, but this should be further investigated. Aeration positively improved NB removal in constructed wetlands, but resulted in higher NB volatilization. Glucose addition induced co-metabolism to enhance NB degradation.
authors.affiliation: Key Laboratory of Clean Utilization Technology for Renewable Energy in Ministry of Agriculture, College of Engineering, China Agricultural University, 100083 Beijing, PR China.
authors.forename: Wesley K
authors.initials: WK
authors.lastname: Kirui
authors.affiliation: Key Laboratory of Clean Utilization Technology for Renewable Energy in Ministry of Agriculture, College of Engineering, China Agricultural University, 100083 Beijing, PR China. Electronic address: wushubiao@cau.edu.cn.
authors.forename: Shubiao
authors.initials: S
authors.lastname: Wu
authors.affiliation: Key Laboratory of Clean Utilization Technology for Renewable Energy in Ministry of Agriculture, College of Engineering, China Agricultural University, 100083 Beijing, PR China; College of Agricultural and Environmental Science, Makerere University, P.O. Box, 7062 Kampala, Uganda.
authors.forename: Simon
authors.initials: S
authors.lastname: Kizito
authors.affiliation: Department of Bioscience, Aarhus University, 8000C Aarhus, Denmark.
authors.forename: Pedro N
authors.initials: PN
authors.lastname: Carvalho
authors.affiliation: Key Laboratory of Clean Utilization Technology for Renewable Energy in Ministry of Agriculture, College of Engineering, China Agricultural University, 100083 Beijing, PR China.
authors.forename: Renjie
authors.initials: R
authors.lastname: Dong
mesh_terms: D001673:Biodegradation, Environmental; D005947:Glucose / Q000737:chemistry*; D009578:Nitrobenzenes / Q000032:analysis*; D010100:Oxygen / Q000737:chemistry*; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D053833:Wetlands
chemical_list: D009578:Nitrobenzenes; D014874:Water Pollutants, Chemical; D005947:Glucose; D010100:Oxygen
keywords: Constructed wetlands; Intermittent aeration; Nitrobenzene; Nitrogen; Sulphur