Performance and stability of the partial nitrification process for nitrogen removal from monosodium glutamate wastewater

The feasibility of using a partial nitrification process for the treatment of monosodium glutamate waste-water was investigated. An airlift bioreactor fed with wastewater produced an appropriate NO2--N/NH4+-N mixture that could serve as an input for an anaerobic ammonium oxidation process. Moreover, the impact of transient overload, resulting in an increase in the ammonium concentration, on the stability of the PN process was also explored. Strict control of the pH, dissolved oxygen concentration, temperature, and ammonium concentration and load was adopted as the main combination operational strategy to maintain a stable partial nitrification process. A nitrite yield of up to 87.0% and an effluent NO2--N/NH4+-N ratio of 1.33, suitable for the influent of the subsequent ANAMMOX process, was observed. In addition, the capacity for ammonium conversion determined by increasing the influent NH4+-N concentration and reducing the hydraulic retention time were 1.2 and 1.83 g N/(L d), respectively. The shock experiment validated that this PN reactor has a good resistance to overload, even at a high concentration of substrate (1260 mg N/L), and that the performance of PN can be quickly restored after cessation of the shock. (C) 2012 Elsevier B.V. All rights reserved.