Upgrading municipal lagoons in temperate and cold climates: Total nitrogen removal and phosphorus assimilation at ultra-low temperatures

Abstract

In this study, a municipal lagoon with high wintertime effluent total ammonia nitrogen (TAN) concentrations was upgraded with a pilot-scale NIT-NIT-DENIT moving bed biofilm reactor (MBBR) treatment train to characterize its effluent over wintertime operation, investigate the feasibility of upgrading lagoons to achieve substantial biological total nitrogen removal across ultra-low temperatures (0.6 – 3.0°C) and investigate nitrification inhibition pathways in facultative lagoon systems at ultra-low temperatures. Throughout the study, it was observed that the system substantially reduced total nitrogen (TN) and total phosphorus (TP) effluent concentrations by an average of 69.0 ± 24.5% and 74.7 ± 20.1%, respectively, with average TN and TP concentrations exiting the treatment train of 7.60 ± 5.60 mg-N/L and 0.05 ± 0.02 mg-P/L, respectively, indicating the feasibility of upgrading municipal lagoons to meet increasing stringent effluent standards to ensure the perenniality of water resources. Furthermore, it was observed that sulfide toxicity may play an important role in the inhibition of nitrifying organisms in lagoons.