title: Enhancement of sludge granulation in hydrolytic acidogenesis by denitrification.
abstract: Acidogenesis is an important pretreatment process for various industrial wastewater treatments. Granular sludge is an efficient form of a microbial community in anaerobic methanogenic reactors, such as upflow anaerobic sludge blanket (UASB), but it is hard to develop in the acidogenic process due to the short hydraulic retention times (HRTs) of acidogenesis. In this study, nitrate was added into an acidogenic reactor as an electron acceptor to enhance electron exchange between acidogenic and denitrifying bacteria to accelerate sludge growth in the acidogenesis process. The results showed that it developed solid and mature granular sludge with a mean size of 410 ± 35 μm over 84 days of operation. Comparatively, the sludge in a no-nitrate acidogenic reactor showed a flocculent appearance with a mean size of 110 ± 18 μm. Analysis of the microbial community indicated that denitrifying bacteria interwoven with propionate-oxidizing bacteria were distributed in the outer granule layer, which provided an ideal shield for susceptible microorganisms inside the granules. This microbial structure was favorable for the development of granular sludge and made the system possible to respond well to shocks in the operation.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China. zhangyb@dlut.edu.cn.
authors.forename: Yaobin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Zisheng
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Songlan
authors.initials: S
authors.lastname: Sun
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Xie
authors.initials: X
authors.lastname: Quan
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Zhao
mesh_terms: D000693:Anaerobiosis; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D019149:Bioreactors; D058440:Denitrification / Q000502:physiology*; D005427:Flocculation; D006801:Humans; D006868:Hydrolysis; D059013:Microbial Consortia / Q000235:genetics*; D009566:Nitrates / Q000378:metabolism; D010084:Oxidation-Reduction; D011422:Propionates / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D014865:Waste Disposal, Fluid
chemical_list: D009566:Nitrates; D011422:Propionates; D012722:Sewage
keywords: Acidogenic; Denitrification; Electron exchange; Sludge granulation