Unveiling interactions between anammox and denitrification from long-term steady-state scale and transient kinetic
Hao Tan1, Fengjun Yin2, Jinjin Zheng2
1Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Abstract:
Interactions in hybrid anammox and denitrification sludge (HADS) systems were unveiled through the effects of carbon to nitrogen (C/N) and nitrite to nitrate (Nit/Nat) ratios in long-term steady-state scale and transient kinetic scale. In nitrite-only feed (SAD1), increasing C/N ratio in long-term operation reduced effluent nitrate to 2.9 mgN/L, achieving a total nitrogen removal efficiency (TNre) of 88.6%. Competitive interaction with full denitrification dominated in SAD1 as revealed by the transient experiment, causing that C/N ratio higher than 0.75 was unsustainable for HADS maintenance. In mixed feed (SAD2), reducing Nit/Nat ratio from 4 to 0 resulted in a TNre of 93.8%, with anammox contributing 98.3%. Excellent synergistic interaction with partial denitrification in SAD2 was derived from the electron competition effect of nitrate on nitrite reduction. The optimal HADS operation occurred with C/N between 2-3 and Nit/Nat below 0.5. These results deepen the understanding of HADS system and facilitate its operation.
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