Pilot-Scale Evaluation of ANITATM Mox for Centrate Nitrogen Removal at the Joint Water Pollution Control Plant

The Sanitation Districts of Los Angeles County (Districts) evaluated two variants of Kruger/Veolia’s ANITA Mox process for removing centrate nitrogen at the Joint Water Pollution Control Plant (JWPCP) in Carson, California. One variant was based on the Moving Bed Biofilm Reactor (MBBR) technology, while the other was based on the Integrated Fixed-Film Activated Sludge (IFAS) technology. Two different centrate streams (“Pre-DAF” and “Post-DAF”) were tested as feed to the MBBR pilot; one (“Pre-DAF”) was tested with the IFAS pilot. Due to dilution by other process water, both centrate streams contained lower concentration of NH4 than typical centrate. Median feed NH4 concentrations during this study were 634 mgN/L (Pre-DAF) and 469 mgN/L (Post-DAF).Despite its low strength, JWPCP centrate was treatable by ANITA Mox. With Post-DAF as feed, the MBBR pilot demonstrated removal rates of 1.3 gN/m2-d (NH4) and 1.1 gN/m2-d (TIN), with corresponding removal efficiencies of 85% (NH4) and 70% (TIN). With Pre-DAF as feed, after process optimization, the MBBR pilot achieved higher removal rates of 2.1 gN/m2-d (NH4) and 1.9 gN/m2-d (TIN), with corresponding removal efficiencies of 75% (NH4) and 68% (TIN). Removal rates showed attenuated response to operating temperature. The IFAS pilot demonstrated significantly higher rates than the current generation of single-stage deammonification technologies. With Pre-DAF as feed, removal rates of 7.8 g/m2-d (NH4) and 6.7 g/m2-d (TIN), with corresponding removal efficiencies of 78% (NH4) and 68% (TIN), were achieved.Robustness of the MBBR pilot was evaluated in six scenarios designed to simulate various commonly-encountered operational outages/events: (1) Power Outage; (2) No Feed NH4; (3) Overfeed; (4) Excess Mannich Polymer in Feed; (5) No Aeration; and (6) Over-aeration. Of these scenarios, “No aeration”, “Overfeed”, and “Excess Mannich Polymer in Feed” resulted in temporary performance loss. Even in the worst case, performance fully recovered within 2 days. No special shut-down/start-up procedure was necessary. The offgas of both pilots were analyzed for two potent greenhouse gases, N2O and CH4. The MBBR pilot emitted 0.52% of the influent TKN as N2O, substantially lower than had been reported for the competing DEMON process (1.3%). The IFAS pilot emitted 1.7% of the influent TKN as N2O.