Rapid start-up and performance of denitrifying granular sludge in an upflow sludge blanket (USB) reactor treating high concentration nitrite wastewater
Denitrifying granular sludge reactor holds better nitrogen removal efficiency than other kinds of denitrifying reactors, while this reactor commonly needs seeding anaerobic granular sludge and longer period for start-up in practice, which restricted the application of denitrifying granular sludge reactor. This study presented a rapid and stable start-up method for denitrifying granular sludge. An upflow sludge blanket (USB) reactor with packings was established with flocculent activated sludge for treatment of high concentration nitrite wastewater. Results showed mature denitrifying granular sludge appeared only after 15 days with highest nitrogen removal rate of 5.844 kg N/(m3 day), which was much higher than that of compared anoxic sequencing batch reactor (ASBR). No significant nitrite inhibition occurred in USB and denitrification performance was mainly influenced by hydraulic retention time, influent C/N ratio and internal reflux ratio. Hydraulic shear force created by upflow fluid, shearing of gaseous products and stable microorganisms adhesion on the packings might be the reasons for rapid achievement of granular sludge. Compared to inoculated sludge and ASBR, remarkable microbial communitiy variations were detected in USB. The dominance of Proteobacteria and Bacteroidetes and enrichment of species Pseudomonas_stutzeri should be responsible for the excellent denitrification performance, which further verified the feasibility of start-up method.
KeywordsDenitrification High nitrite concentration Upflow sludge blanket Granular sludge Rapid start-up Microbial community analysis
This research was supported by the Specialized Applied Technology Research and Development (major) of Guangdong Province in 2015 (2015B020235013), the Specialized Applied Science and Technology Research, Development and Major Transformation Project of Guangdong Province in 2017 (2017B020236004) and The Pearl River S&T Nova Program of Guangzhou (201610010069).
- China EPA (2002) Standard methods of examination of water and wastewater, 4th edn. Chinese Environmental Sciences Press, BeijingGoogle Scholar
- Wu JL, Bi L, Zhang JB, Poncin S, Cao ZP, Li HZ (2012) Effects of increase modes of shear force on granule disruption in upflow anaerobic reactors. Water Res 46:3186–3196Google Scholar