title: Start-up of granule-based denitrifying reactors with multiple magnesium supplementation strategies.
abstract: In the present work, the effect of Mg(2+) supplementation on the start-up of a denitrification process and the granulation of denitrifying sludge was investigated in three upflow anaerobic sludge blanket (UASB) reactors. The reactors R1 and R2 were continuously and intermittently, respectively, supplied with 50 mg L(-1) Mg(2+), whereas R0 was used as the control. The nitrogen loading rate (NLR) and organic loading rate (OLR) gradually increased, and extremely high values were obtained (36.0 kgN m(-3) d(-1) and 216.0 kgCOD m(-3) d(-1), respectively). Granulation occurred in R1 first, but the reactor capacities were comparable. Suffering from starvation, the R0-R2 performances were comparable. At the end of the experiment, the average diameter of the granules in R0, R1, and R2 were 1.67, 1.72 and 1.68 mm, respectively, and the settling velocities of the granules in R1 and R2 were 1.14-fold the speed of R0. The specific denitrifying activity (SDA) of the sludge from the reactors supplied with Mg(2+) was greater than the reactor without Mg(2+). Intermittent Mg(2+) supplementation was identified as the best choice to be utilized to cultivate denitrifying granules, which was consistent with kinetic analysis.
authors.affiliation: Department of Environmental Science and Engineering, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Environmental Science and Engineering, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Li-Ling
authors.initials: LL
authors.lastname: He
authors.affiliation: Department of Environmental Science and Engineering, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: An-Na
authors.initials: AN
authors.lastname: Liu
authors.affiliation: Department of Environmental Science and Engineering, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Department of Environmental Science and Engineering, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Zheng-Zhe
authors.initials: ZZ
authors.lastname: Zhang
authors.affiliation: Department of Environmental Science and Engineering, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China. Electronic address: jrczju@aliyun.com.
authors.forename: Ren-Cun
authors.initials: RC
authors.lastname: Jin
mesh_terms: D019149:Bioreactors; D058440:Denitrification; D006801:Humans; D008274:Magnesium / Q000737:chemistry*; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D012722:Sewage; D008274:Magnesium
keywords: Denitrification; Granulation; Kinetic; Magnesium; Mineral content