title: Improving oxygen dissolution and distribution in a bioreactor with enhanced simultaneous COD and nitrogen removal by simply introducing micro-pressure and swirl.
abstract: Increasingly, environmental regulations are demanding more exacting chemical oxygen demand (COD) and nitrogen removal from wastewater, which come at a high economic cost. A very simple novel bioreactor, the micro-pressure swirl reactor (MPSR), can improve the dissolution and distribution of oxygen by the introduced micro-pressure swirl. Comparison with a conventional sequencing batch reactor (SBR) over 76 days of operation showed that this method can enhance simultaneous COD and nitrogen removal. By installing an aeration diffuser on one side of the two-dimensional MPSR, a swirl formed in the bioreactor that extended the retention time of the air bubbles. This unique flow regime, combined with the micro-pressure caused by the elevated water surface at the bubble outflow point, resulted in a higher level of dissolved oxygen (DO) in the MPSR. Aerobic and anaerobic zones that created appropriate conditions for simultaneous COD and nitrogen removal also formed in the MPSR. As the organic loading rate increased from 0.29 to 1.68 g COD/(L · day) over the test period, the COD removal efficiencies of the MPSR were generally 10-20 % greater than those of the SBR. In particular, the total nitrogen (TN) removal efficiencies of the MPSR and SBR were 40-50 and 20-35 %, respectively, whereas the TN concentrations in the MPSR effluent were always around 10 mg/L lower than those of the SBR. Further, because of the unique DO distribution, the bacterial species in the MPSR were more diverse and contributed to enhanced TN removal.
authors.affiliation: School of Environment, Northeast Normal University, Changchun, 130024, China.|School of Water Conservancy and Environment, Changchun Institute of Technology, Changchun, 130012, China.|Key Laboratory of Urban Sewage Treatment of Jilin Province, Changchun, 130012, China.
authors.forename: Dejun
authors.initials: D
authors.lastname: Bian
authors.affiliation: School of Environment, Northeast Normal University, Changchun, 130024, China. zhoudandan415@163.com.
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhou
authors.affiliation: School of Environment, Northeast Normal University, Changchun, 130024, China. huomx097@nenu.edu.cn.
authors.forename: Mingxin
authors.initials: M
authors.lastname: Huo
authors.affiliation: School of Water Conservancy and Environment, Changchun Institute of Technology, Changchun, 130012, China.|Key Laboratory of Urban Sewage Treatment of Jilin Province, Changchun, 130012, China.
authors.forename: Qingkai
authors.initials: Q
authors.lastname: Ren
authors.affiliation: School of Water Conservancy and Environment, Changchun Institute of Technology, Changchun, 130012, China.|Key Laboratory of Urban Sewage Treatment of Jilin Province, Changchun, 130012, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Tian
authors.affiliation: School of Water Conservancy and Environment, Changchun Institute of Technology, Changchun, 130012, China.|Key Laboratory of Urban Sewage Treatment of Jilin Province, Changchun, 130012, China.
authors.forename: Liguo
authors.initials: L
authors.lastname: Wan
authors.affiliation: School of Environment, Northeast Normal University, Changchun, 130024, China.
authors.forename: Suiyi
authors.initials: S
authors.lastname: Zhu
authors.affiliation: School of Environment, Northeast Normal University, Changchun, 130024, China.|School of Water Conservancy and Environment, Changchun Institute of Technology, Changchun, 130012, China.|Key Laboratory of Urban Sewage Treatment of Jilin Province, Changchun, 130012, China.
authors.forename: Shengshu
authors.initials: S
authors.lastname: Ai
mesh_terms: D000332:Aerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D003470:Culture Media / Q000737:chemistry*; D009584:Nitrogen / Q000378:metabolism; D010100:Oxygen / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D003470:Culture Media; D009584:Nitrogen; D010100:Oxygen
keywords: Dissolved oxygen; Isocline; Micro-pressure; Simultaneous nitrification and denitrification; Swirl