Effect of process parameters and operational mode on nitrous oxide emissions from a nitritation reactor treating reject wastewater

Nitrogen is a main contaminant of wastewater worldwide. Novel processes for nitrogen removal have been developed over the last several decades. One of these is the partial nitritation process. This process includes the oxidation of ammonium to nitrite without the generation of nitrate. The partial nitritation process has several advantages over traditional nitrification-denitrification processes for nitrogen removal from wastewaters. In addition, partial nitritation is required for anammox elimination of nitrogen from wastewater. Partial nitritation is affected by operational conditions and substances present in the influent, such as quinolone antibiotics. In this review, the impact that several operational conditions, such as temperature, pH, dissolved oxygen concentration, hydraulic retention time and solids retention time, have over the partial nitritation process is covered. The effect of quinolone antibiotics and other emerging contaminants are discussed. Finally, future perspectives for the partial nitritation process are commented upon.

Section: Effect Of Ph and Domentioning

confidence: 99%

The Effect of Influent Characteristics and Operational Conditions over the Performance and Microbial Community Structure of Partial Nitritation Reactors

Rodríguez-Sánchez

González‐Martínez

Martı́nez-Toledo

et al. 2014

“…Factors affecting N2O emission during nitrification and denitrification include DO (or aeration rate), SRT, NO2-N, intermittent aeration operating mode, the NH4-N loading rate, and so on [14][15][16][17][18][19]. During treatment of high ammonium containing wastewater, achieving nitritation means the production of high concentrations of nitrite, which may lead to increased N2O emission [14].…”

Section: Introductionmentioning

confidence: 99%

Nitritation and N2O Emission in a Denitrification and Nitrification Two-Sludge System Treating High Ammonium Containing Wastewater

Zheng

Xing

2014

Abstract:The effective management of high ammonium containing wastewater is important for the sustainable development of the wastewater industry. A pre-denitrification and post-nitrification two-sludge system was proposed to treat high ammonium containing wastewater with low carbon-to-nitrogen (C/N) ratios. In the system, pre-denitrification was adopted to use organic carbon in raw wastewater efficiently for nitrogen removal, while post-nitrification was adopted to achieve nitritation. System performance and the characteristics of nitrous oxide (N2O) emission were examined. As to the influent chemical oxygen demand (COD) and ammonium nitrogen (NH4-N) concentration, both 800 mg/L, nitrogen removal was mainly through pre-denitrification, and the nitrogen removal percentage was 43.4%. In post-nitrification, nitritation was achieved with a nitrite accumulation efficiency of 97.8% and a NH4-N removal loading rate of 0.45 g/(L·d). With nitrite as the electron acceptor during denitrification, its removal rate increased, while the N2O emission factor decreased with increasing C/N ratios. Nitrification was affected significantly by the aeration rate. When the aeration rate was below 0.6 L/min, the NH4-N removal rate increased, while the N2O emission rate decreased with increasing aeration rates. However, when the aeration rate was above 0.6 L/min, it had little influence on N2O OPEN ACCESSWater 2014, 6 2979 emission. During nitrification, N2O emission factors decreased exponentially with increasing ammonium oxidation rates.

“…N 2 O emissions during nitrifier denitrification and heterotrophic denitrification have been known to be executed by certain bacteria species, mainly AOB and denitrifiers [14,15]. To determine the mechanism of N 2 O emission in aerobic granular sludge, the genes nirK and nosZ, which represented the denitrification of AOB, and denitrifiers were quantified using qPCR method.…”

Section: N 2 O Emission Of Aerobic Granular Sludgementioning

confidence: 99%

Effects of the Food-to-Microorganism (F/M) Ratio on N2O Emissions in Aerobic Granular Sludge Sequencing Batch Airlift Reactors

Guo

Zhang

Xie

et al. 2017

The present study investigated the effect of the food-to-microorganism (F/M) ratio on nitrous oxide (N 2 O) emissions in aerobic granular sludge sequencing batch airlift reactors. Three identical sequencing batch airlift reactors were fed with sodium acetate-based wastewater at different chemical oxygen demand (COD) concentrations, resulting in F/M ratios from 0.2 to 0.67 g COD/g SS. The results indicated that N 2 O emissions increased with an increase of the F/M ratio. N 2 O emissions at the high F/M ratio of 0.67 g COD/g SS were the highest (4.4 ± 0.94 mg/d). The main source of the high N 2 O emissions at the F/M ratio of 0.67 g COD/g SS was nitrifier denitrification, rather than heterotrophic denitrification, confirmed by the qPCR (quantitative real-time PCR) results. The heterotrophic denitrification was destroyed by the DO (dissolved oxygen) diffusing into the sludge particles with porous structures. This study offers theoretical support to study the N 2 O emissions in aerobic granular sludge, and can provide guidance for conducting risk assessment and enhancing our ability to predict N 2 O production in aerobic granular sludge at different F/M ratios.