Nitrogen Removal From Municipal Wastewater Using a Two‐Sludge Denitrification/Nitrification Batch Reactor: Performance and Mechanisms

Abstract

Biosorption is a common phenomenon, in that organics in wastewater are trapped by sludge flocs. To achieve high nitrogen removal efficiency from the treatment of low chemical oxygen demand (COD) content wastewater, a two‐sludge denitrification/nitrification batch reactor (TDNBR) is successfully established based on the sorption of organic matter by anoxic activated sludge. During 123 days of operation, the TDNBR achieved high ammonia (>99%) and total nitrogen (TN) (80%) removal efficiency. A higher C/N ratio and exchange frequency have no obvious effect on nitrification but effectively enhanced denitrification. The sorption assays indicated that anoxic sludge could take up a large amount of organic matter (23.79–55.62 mg COD g−1 TSS) but has a low sorption capacity of NH4+‐N. Nitrate utilization rate tests reveal that both the soluble and colloidal organics pre‐sorbed on the sludge can be utilized in denitrification with few organics stored as PHA in bacterial cells. Through cyclic study analysis, it was found that, by interchanging the supernatant in oxic and anoxic tanks alternately, nitrification and denitrification processes are successfully separated and high ammonia and TN removal efficiencies are achieved.

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“…The dissolved organic nitrogen is removed at an efficiency of 60−80% depending on the different technologies involved. 57 In this study, we have applied a mean 70% removal efficiency for the organic nitrogen removal. The remaining diethyl amine is discharged into the environment as COD and BOD.…”

“…Hydrazine can be degraded into N 2 . The dissolved organic nitrogen is removed at an efficiency of 60–80% depending on the different technologies involved . In this study, we have applied a mean 70% removal efficiency for the organic nitrogen removal.…”