Effect of Solids Retention Time on Nitrogen Removal and Microbial Consortium in a Novel Algal-Bacterial Shortcut Nitrogen Removal System

2017 ◽  
Vol 2017 (3) ◽  
pp. 225-230
Author(s):  
Nadezhda Zalivina ◽  
Ryan Keeley ◽  
Larissa T Arashiro ◽  
Angelica Rada-Ariza ◽  
Meng Wang ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Retention Time ◽  
Microbial Consortium ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Shortcut Nitrogen Removal ◽  
Removal System

Nitrogen removal in activated sludge systems including denitrification in secondary clarifiers

1994 ◽  
Vol 30 (6) ◽  
pp. 101-111 ◽  
Author(s):  
H. Siegrist ◽  
W. Gujer
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Retention Time ◽  
Secondary Clarifier ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Activated Sludge Systems

Denitrification in the secondary clarifier can contribute substantially to the nitrogen removal of activated sludge systems. This is illustrated on two treatment plants with different secondary clarifier systems. A model to estimate denitrification capacity and to design activated sludge systems for nitrogen removal is developed and verified with data from two treatment plants. The model includes denitrification in the secondary clarifier, wastewater composition (soluble readily biodegradable COD, particulate degradable COD), oxygen input into the anoxic volume, temperature, and solids retention time (SRT). The influence of aerated grit chambers and primary sedimentation on denitrification is discussed.

Shall we upgrade one-dimensional secondary settler models used in WWTP simulators? – An assessment of model structure uncertainty and its propagation

2011 ◽  
Vol 63 (8) ◽  
pp. 1726-1738 ◽  
Author(s):  
Benedek Gy. Plósz ◽  
Jeriffa De Clercq ◽  
Ingmar Nopens ◽  
Lorenzo Benedetti ◽  
Peter A. Vanrolleghem
Keyword(s):  
Nitrogen Removal ◽  
Retention Time ◽  
Dispersion Model ◽  
Model Structure ◽  
One Dimensional ◽  
Biokinetic Model ◽  
Solids Concentration ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Simulation Results

In WWTP models, the accurate assessment of solids inventory in bioreactors equipped with solid-liquid separators, mostly described using one-dimensional (1-D) secondary settling tank (SST) models, is the most fundamental requirement of any calibration procedure. Scientific knowledge on characterising particulate organics in wastewater and on bacteria growth is well-established, whereas 1-D SST models and their impact on biomass concentration predictions are still poorly understood. A rigorous assessment of two 1-DSST models is thus presented: one based on hyperbolic (the widely used Takács-model) and one based on parabolic (the more recently presented Plósz-model) partial differential equations. The former model, using numerical approximation to yield realistic behaviour, is currently the most widely used by wastewater treatment process modellers. The latter is a convection-dispersion model that is solved in a numerically sound way. First, the explicit dispersion in the convection-dispersion model and the numerical dispersion for both SST models are calculated. Second, simulation results of effluent suspended solids concentration (XTSS,Eff), sludge recirculation stream (XTSS,RAS) and sludge blanket height (SBH) are used to demonstrate the distinct behaviour of the models. A thorough scenario analysis is carried out using SST feed flow rate, solids concentration, and overflow rate as degrees of freedom, spanning a broad loading spectrum. A comparison between the measurements and the simulation results demonstrates a considerably improved 1-D model realism using the convection-dispersion model in terms of SBH, XTSS,RAS and XTSS,Eff. Third, to assess the propagation of uncertainty derived from settler model structure to the biokinetic model, the impact of the SST model as sub-model in a plant-wide model on the general model performance is evaluated. A long-term simulation of a bulking event is conducted that spans temperature evolution throughout a summer/winter sequence. The model prediction in terms of nitrogen removal, solids inventory in the bioreactors and solids retention time as a function of the solids settling behaviour is investigated. It is found that the settler behaviour, simulated by the hyperbolic model, can introduce significant errors into the approximation of the solids retention time and thus solids inventory of the system. We demonstrate that these impacts can potentially cause deterioration of the predictive power of the biokinetic model, evidenced by an evaluation of the system's nitrogen removal efficiency. The convection-dispersion model exhibits superior behaviour, and the use ofthis type of model thus is highly recommended, especially bearing in mind future challenges, e.g., the explicit representation of uncertainty in WWTP models.

Bulking and Foaming Organism Control at Phoenix, AZ WWTP

1992 ◽  
Vol 26 (3-4) ◽  
pp. 461-472 ◽  
Author(s):  
O. E. Albertson ◽  
P. Hendricks
Keyword(s):  
Wastewater Treatment ◽  
Nitrogen Removal ◽  
Retention Time ◽  
Oxygen Transfer ◽  
Average Rate ◽  
Oxygen Transfer Efficiency ◽  
Solids Retention ◽  
Total Nitrogen Removal ◽  
The Cost ◽  
The City

A 1630 L/s activated sludge plant at Phoenix was limited to an average rate of 1050 L/s and operated, at 400-600 mg/L MLSS and 0.8-1.3 day solids retention time (SRT) due to bulking sludge and limited clarification capacity. Higher SRTs also produced uncontrolled Nocardia foaming and low dissolved oxygen due to partial nitrification. The City retained the services of a team of consultants to resolve these problems as well as to upgrade the plant to provide nitrification and total nitrogen removal. An anoxic selector design was implemented within the existing basin and the clarifiers were modified to improve inlet design and sludge transport. The modified advanced wastewater treatment (AWT) plant operating at 1450 L/s has averaged an effluent of 7.6 mg/L BOD5, 8.2 mg/L TSS, 1.3 mg/L NH4N, 4.1 mg/L NO3N and 2.9 mg/L TP. Oxygen transfer efficiency has increased about 80% in the nitrification-denitrification (NdeN) mode. The cost of modification/upgrading to AWT was approximately $730,000 and a 400 L/s increase in hydraulic capacity was realized. Upgrading costs were $5.63/m3 ($0.02/gal.)

Impact of solids retention time on dissolved organic nitrogen and its biodegradability in treated wastewater

2016 ◽  
Vol 92 ◽  
pp. 44-51 ◽  
Author(s):  
Halis Simsek ◽  
Murthy Kasi ◽  
Jae-Bom Ohm ◽  
Sudhir Murthy ◽  
Eakalak Khan
Keyword(s):  
Retention Time ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Treated Wastewater ◽  
Solids Retention Time ◽  
Solids Retention

scholarly journals Effect of solids retention time on Microthrix parvicella growth

Water SA ◽  
2007 ◽  
Vol 32 (3) ◽  
Author(s):  
C Noutsopoulos ◽  
D Mamais ◽  
A Andreadakis
Keyword(s):  
Retention Time ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Microthrix Parvicella
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