Effect of self-alkalization on nitrite accumulation in a high-rate denitrification system: performance, microflora and enzymatic activities
The self-alkalization of denitrifying automatic circulation(DAC)reactor resulted in a large increase of pH up to 9.20 and caused a tremendous accumulation of nitrite up to 451.1±49.0 mgN·L-1 at nitrate loading rate(NLR)from 35 kgN·m-3·d-1 to 55 kgN·m-3·d-1.The nitrite accumulation was greatly relieved even at the same NLR once the pH was maintained at 7.6±0.2 in the system.Enzymatic assays indicated that the long-term bacterial exposure to high pH significantly inhibited the activity of copper type nitrite reductase(NirK)rather than the cytochrome cd1 type nitrite reductase(NirS).The terminal restriction fragment length polymorphism(T-RFLP)analysis revealed that the dominant denitrifying bacteria shifted from the NirS-containing Thauear sp.27 to the NirK-containing Hyphomicrobium nitrativorans strain NL23 during the self-alkalization.The significant nitrite accumulation in the high-rate denitrification system could be therefore,due to the inhibition of Cu-containing NirK by high pH from the self-alkalization.The results suggest that the NirK-containing H.nitrativorans strain NL23 could be an ideal functional bacterium for the conversion of nitrate to nitrite,i.e.denitritation,which could be combined with anaerobic ammonium oxidation(Anammox)to develop a new process for nitrogen removal from wastewater.
Denitrification High-load Self-alkalization Nitrite accumulation Microbial mechanism
Wei Li Ping Zheng
Department of Environmental Engineering,College of Environmental and Resource Science,Zhejiang University,Hangzhou,China
国内会议
上海
英文
1-30
2015-11-06（万方平台首次上网日期，不代表论文的发表时间）