The effect of dissolved oxygen concentration (DO) on oxygen diffusion and bacterial community structure in moving bed sequencing batch reactor (MBSBR). (1st January 2017)

• Record Type: Journal Article
• Authors: Cao, Yongfeng; Zhang, Chaosheng; Rong, Hongwei; Zheng, Guilin; Zhao, Limin
• Is Part Of: Water research. Volume 108(2017)
• Page Start: 86
• Page End: 94
• Publication Date: 2017-01-01
• Subjects: Moving bed sequencing batch reactor (MBSBR) -- Dissolved oxygen concentration (DO) -- Microelectrode -- Simultaneous nitrification and denitrification (SND) -- Real-time PCR; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2016.10.063
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: The effect of dissolved oxygen concentration (DO) on simultaneous nitrification and denitrification was studied in a moving bed sequencing batch reactor (MBSBR) by microelectrode measurements and by real-time PCR. In this system, the biofilm grew on polyurethane foam carriers used to treat municipal sewage at five DO concentrations (1.5, 2.5, 3.5, 4.5 and 5.5 mg/L). The results indicated that the MBSBR exhibited good removal of chemical oxygen demand (92.43%) and nitrogen (83.73%) when DO concentration was 2.5 mg/L. Increasing the oxygen concentration in the reactor was inhibitory to denitrification. Microelectrode measurements showed that the thickness of oxygen penetration increased from 1.2 to 2.6 mm when the DO concentration (from 1.5 mg/L to 5.5 mg/L) in the system increased. Oxygen diffusion was not significantly limited by the boundary layer surrounding the carrier and had the largest slope when DO concentration was 2.5 mg/L. The real-time PCR analysis indicated that the amount of the ammonia-oxidizing bacteria and nitrite-oxidizing bacteria increased slowly as DO concentration increased. The proportions of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, as a percentage of the total bacteria, were low with average values of 0.063% and 0.67%, respectively. When the DO concentration was 2.5 mg/L, oxygen diffusion was optimal and ensured the optimal bacterial community structure and activity; under these conditions, the MBSBR was efficient for total inorganic nitrogen removal. Changing the DO concentration could alter the aerobic zone and the bacterial community structure in the biofilm, directly influencing the simultaneous nitrification and denitrification activity in MBSBRs. Graphical abstract: Highlights: DO concentration should be strictly controlled to achieve SND in the MBSBR. Microelectrodes gives suitable information for optimization of MBSBR system. The relation between community structure and DO concentrations was analyzed in system.