Enhanced Nitrogen Removal from Domestic Wastewater by Partial-Denitrification/Anammox in an Anoxic/Oxic Biofilm Reactor

Abstract

A partial-denitrification coupling with anaerobic ammonium oxidation (anammox) process (PD/A) in a continuous-flow anoxic/oxic (A/O) biofilm reactor was developed to treat carbon-limited domestic wastewater (ammonia (NH4+-N) of 55 mg/L and chemical oxygen demand (COD) of 148 mg/L in average) for about 200 days operation. Satisfactory NH4+-N oxidation efficiency above 95% was achieved with rapid biofilm formation in the aerobic zone. Notably, nitrite (NO2−-N) accumulation was observed in the anoxic zone, mainly due to the insufficient electron donor for complete nitrate (NO3−-N) reduction. The nitrate-to-nitrite transformation ratio (NTR) achieved was as high as 64.4%. After the inoculation of anammox-enriched sludge to anoxic zones, total nitrogen (TN) removal was significantly improved from 37.3% to 78.0%. Anammox bacteria were effectively retained in anoxic biofilm utilizing NO2−-N produced via the PD approach and NH4+-N in domestic wastewater, with the relative abundance of 5.83% for stable operation. Anammox pathway contributed to TN removal by a high level of 38%. Overall, this study provided a promising method for mainstream nitrogen removal with low energy consumption and organic carbon demand.

Special Issue on “Anammox-Based Processes for Wastewater Treatment”

“…Finally, Huang et al [9] coupled partial denitrification (PD) with anammox (PD/A) on a lab scale in a continuous-flow anoxic/oxic biofilm reactor to treat urban wastewater. Ammonium oxidation to nitrate occurred in the oxic zone, whereas nitrite accumulation occurred in the anoxic zone due to the insufficient availability of organic carbon to complete nitrate reduction to nitrogen gas.…”

Wastewater treatment from a science faculty during the COVID-19 pandemic by using ammonium-oxidising and heterotrophic bacteria

“…NO 3 − , can follow several transformation pathways, one of which is the assimilative reduction of NO 3 − to produce NH 4 + ; them used by microorganisms to synthesise new nitrogen-based cellular compounds, such as amino acids, peptides, proteins and nitrogenous sugars (Huang et al 2020 ). Under anaerobic conditions, NO 3 − is reduced by denitrification and released into the atmosphere as diatomic nitrogen (N 2 ), (Huang et al 2022 ; Marquez Fontalvo et al 2022 ).…”

Ceramic membrane bioreactor for low carbon source wastewater treatment: process design performance and membrane fouling

“…The concentration of organic matter in domestic wastewater is generally low, the traditional activated sludge method based on AO 1,2 and AAO 3,4 is limited to denitrification due to the relative lack of carbon sources, the overall denitrification effect is poor, the actual operation requires the addition of external carbon sources, 5,6 and some of the carbon sources such as methanol 7 are aerobic and potentially dangerous, which greatly increases the operating costs and the difficulty of operational control. The AOA process using postendogenous denitrification is simpler in structure and usually does not require an external carbon source, and it includes good denitrification and phosphorus removal for low C/N domestic wastewater, [8][9][10][11] but is limited by the slow rate of endogenous denitrification, making the postanaerobic zone require a long hydraulic retention time (HRT); 12 otherwise the denitrification intensity is still insufficient.…”