Mainstream ANITA Mox Pilot Testing at the Joint Water Pollution Control Plant

The IFAS (Integrated Fixed-film Activated Sludge) variant of Kruger’s ANITA Mox process was tested in a ten-month pilot study at the Joint Water Pollution Control Plant (JWPCP) for mainstream nitrogen removal via deammonification. The system was used to treat a mixture of non-nitrified secondary effluent (SE) from the facility’s High Purity Oxygen Activated Sludge (HPOAS) and primary effluent (PE). Effects of feed C/N on process performance were evaluated by adjusting the proportion of SE to PE fed to the system. Over the course of the study, the system exhibited median NH4 and TN removal efficiencies of 90% and 71%, and NH4 and TN surface removal rates of 1.29 g/m2-d and 0.97 g/m2-d, at a median process temperature of 25°C. Higher feed C/N correlated with higher TN removal efficiency but lower TN removal rate and poorer sludge settling characteristics. Installation of a selector and switching to the use of fresh instead of stored PE improved sludge settling and effluent quality, and initiated and maintained enhanced biological phosphorus removal (EBPR). Routine media biomass density and Anammox activity testing conducted over the course of the study indicated that anammox activity on the media remained stable under the mainstream conditions tested.