title: Is polymeric substrate in influent an indirect impetus for the nitrification process in an activated sludge system?
abstract: Different from monomeric substrate, polymeric substrate (PS) needs to undergo slow hydrolysis process before becoming available for consumption by bacteria. Hydrolysis products will be available for the heterotrophs in low concentration, which will reduce competitive advantages of heterotrophs to nitrifiers in mixed culture. Therefore, some links between PS and nitrification process can be expected. In this study, three lab-scale sequencing batch reactors with different PS/total substrate (TS) ratio (0, 0.5 or 1) in influent were performed in parallel to investigate the influence of PS on nitrification process in activated sludge system. The results showed that with the increase of PS/TS ratio, apparent sludge yields decreased, while NO3--N concentration in effluent increased. The change of PS/TS ratio in influent also altered the cycle behaviors of activated sludge. With the increase of PS/TS ratio from 0 to 0.5 and 1, the ammonium and nitrite utilization rate increased ∼2 and 3 times, respectively. The q-PCR results showed that the abundance of nitrifiers in activated sludge for PS/TS ratio of 0.5 and 1 were 0.7-0.8 and 1.4-1.5 orders of magnitude higher than that for PS/TS ratio of 0. However, the abundance of total bacteria decreased about 0.5 orders of magnitude from the former two to the latter. The FISH observation confirmed that the nitrifiers' microcolony became bigger and more robust with the increase of PS/TS ratio. This paper paves a path to understand the role of PS/TS in affecting the nitrification process in biological wastewater treatment systems.
authors.affiliation: College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang, China.
authors.forename: Bin-Bin
authors.initials: BB
authors.lastname: Wang
authors.affiliation: College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang, China.
authors.forename: Ya-Wei
authors.initials: YW
authors.lastname: Gu
authors.affiliation: College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang, China.
authors.forename: Jian-Meng
authors.initials: JM
authors.lastname: Chen
authors.affiliation: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Yao
authors.affiliation: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, China.
authors.forename: Hui-Juan
authors.initials: HJ
authors.lastname: Li
authors.affiliation: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, China.
authors.forename: Dang-Cong
authors.initials: DC
authors.lastname: Peng
authors.affiliation: College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang, China. Electronic address: fenghe@zjut.edu.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: He
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D058465:Nitrification; D009584:Nitrogen / Q000302:isolation & purification / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D062065:Wastewater / Q000382:microbiology*
chemical_list: D009584:Nitrogen; D011108:Polymers; D012722:Sewage; D062065:Wastewater
keywords: Activated sludge; Fluorescence in situ hybridization; Nitrification; Polymeric substrate; Quantitative polymerase chain reaction