Optimization for the Operational Parameters of the Partial Nitrification in a Fluidized Bed Bioreactor (PNFBR)

Partial nitrification combined with anaerobic ammonium oxidation (Anammox) process has been recognized as a promising technology for the nitrogen removal in wastewater treatment. This research aimed to focus on how to successfully achieve the partial nitrification in a fluidized bed bioreactor (PNFBR) for the treatment of synthetic wastewater with high ammonia concentration. The influence factors, including dissolved oxygen (DO) levels, free ammonia (FA)/free nitrous acid (FNA) concentration, ambient temperature, influent ammonia concentration, and alkalinity, were investigated to achieve the goal of high nitrite accumulation. Results exhibit that the optimal conditions for the PNFBR was 30 °C with the 7:1 of ratio of alkalinity to influent nitrogen, 1 mg/L of DO concentration, 28 day of SRT, 16.6 day of hydraulic retention time (HRT), and 400 mg/L of influent ammonia concentration. Additionally, at the lower temperature (20 °C), high nitrite accumulation was also attained by increasing the alkalinity (8:1 of ratio of alkalinity to influent nitrogen) in system. Compared with other biofilm system, the PNFBR with the new media mixture of acrylonitrile butadiene styrene (ABS) plastic and its modified one could achieve the effluent requirements for anammox, with the PNFBR effluent NO₂^--N:NH₄⁺-N ratio appropriately at 1:1.