A benchmark simulation to verify an inhibition model on decay stage for nitrification

Activated Sludge Models (ASMs) are widely used for biological wastewater treatment plant design, optimisation and operation. In commonly used ASMs, the nitrification process is modelled as a one-step process. However, in some process configurations, it is desirable to model the concentration of nitr...

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Bibliographic Details
Published in:Water science and technology 2013-01, Vol.68 (6), p.1242-1250
Main Authors: BING LIU, JARVIS, Ian, NAKA, Daisuke, GOEL, Rajeev, YASUI, Hidenari
Format: Article
Language:English
Subjects:
Activated sludge
Ammonia
Ammonium
Ammonium compounds
Applied sciences
Bacteria
Bacteria - metabolism
Benchmarks
Biological treatment
Biological wastewater treatment
Bioreactors - microbiology
Computer simulation
Datasets
Design optimization
Exact sciences and technology
Hydrogen-Ion Concentration
Influents
Inhibition
Kinetics
Marine environment
Models, Biological
Nitrification
Nitrifying bacteria
Nitrites
Nitrogen Compounds - analysis
Nitrogen Compounds - metabolism
Nitrogen Compounds - toxicity
Nitrogen dioxide
Oxygen consumption
Oxygen uptake
pH effects
Plant design
Poisoning
Pollution
Reaction kinetics
Reactors
Sludge
Toxicity
Uptake
Wastewater
Wastewater treatment
Wastewater treatment plants
Water Pollutants, Chemical - analysis
Water Pollutants, Chemical - metabolism
Water Pollutants, Chemical - toxicity
Water treatment and pollution
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Summary:Activated Sludge Models (ASMs) are widely used for biological wastewater treatment plant design, optimisation and operation. In commonly used ASMs, the nitrification process is modelled as a one-step process. However, in some process configurations, it is desirable to model the concentration of nitrite nitrogen through a two-step nitrification process. In this study, the benchmark datasets published by the Water Environment Research Foundation (WERF) were used to develop a two-step nitrification model considering the kinetics of Ammonium Oxidising Bacteria (AOB) and Nitrite Oxidising Bacteria (NOB). The WERF datasets were collected from a chemostat reactor fed about 1,000 mg-NH3-N/L synthetic influent with at different sludge retention times of 20, 10 and 5-d, whereas the pH in the reactor varied in the range of 5.8 and 8.8. Supplemental laboratory batch experiments were conducted to assess the toxicity of nitrite-N on nitrifying bacteria. These tests suggested that 500 mg-N/L of nitrite at pH 7.3 was toxic to NOB and resulted in continuous decrease in bulk oxygen uptake rate. To model this phenomenon, a poisoning model was used instead of the traditional Haldane-type inhibition model. The poisoning model for NOB and AOB with different threshold poisonings for unionised NO2-N and NH3-N concentrations could successfully reproduce the three WERF datasets.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2013.327