Steady-state and dynamic analysis of the single-stage anammox granular sludge reactor show that bulk ammonium concentration is a critical control variable to mitigate feeding disturbances

Chemosphere
Miao ZhangJun Wu

Abstract

One of the challenges for the application of the ANAMMOX (anaerobic ammonium oxidation) process for nitrogen removal in the mainstream municipal wastewater treatment is the disturbances in the feeding influent, in terms of the organic material, ammonium concentration, flow rate and temperature. Past experimental and mathematical simulation researches were mainly carried out under stable feeding condition. It is not clear how the ANAMMOX responds to the feeding disturbances. In this study, a 1D (one-dimensional) biofilm model was used to examine the behavior of feeding disturbances in the single-stage granule PN-A (partial nitrification -ANAMMOX) process. The results indicated that the feeding disturbances could be mitigated by maintaining a small amount of ammonium in the bulk liquid. A cascade control strategy based on DO (dissolved oxygen) manipulation to derive the preset bulk ammonium set-point value (i.e., 2 mg N/L) was shown to be successful in achieving the maximum TN (total nitrogen) removal percentage of above 95% under dynamic feeding conditions. The long-term simulation showed that the small bulk ammonium accumulation could also suppress the NOB (nitrite-oxidizing bacteria) growth.

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