Development of a flocculation sub-model for a 3-D CFD model based on rectangular settling tanks

2011 ◽  
Vol 63 (2) ◽  
pp. 213-219 ◽  
Author(s):  
M. Gong ◽  
S. Xanthos ◽  
K. Ramalingam ◽  
J. Fillos ◽  
K. Beckmann ◽  
...  
Keyword(s):  
New York ◽  
Suspended Solids ◽  
Cfd Model ◽  
Mixed Liquor ◽  
City College ◽  
Solids Loading ◽  
Before And After ◽  
Computational Fluid Dynamics Cfd ◽  
3D Computer Model ◽  
Relationship Of

To assess performance and evaluate alternatives to improve the efficiency of rectangular Gould II type final settling tanks (FSTs), New York City Department of Environmental Protection and City College of NY developed a 3D computer model depicting the actual structural configuration of the tanks and the current and proposed hydraulic and solids loading rates. Fluent 6.3.26™ was the base platform for the computational fluid dynamics (CFD) model, for which sub-models of the SS settling characteristics, turbulence, flocculation and rheology were incorporated. This was supplemented by field and bench scale experiments to quantify the coefficients integral to the sub-models. The 3D model developed can be used to consider different baffle arrangements, sludge withdrawal mechanisms and loading alternatives to the FSTs. Flocculation in the front half of the rectangular tank especially in the region before and after the inlet baffle is one of the vital parameters that influences the capture efficiency of SS. Flocculation could be further improved by capturing medium and small size particles by creating an additional zone with an in-tank baffle. This was one of the methods that was adopted in optimizing the performance of the tank where the CCNY 3D CFD model was used to locate the in-tank baffle position. This paper describes the development of the flocculation sub-model and the relationship of the flocculation coefficients in the known Parker equation to the initial mixed liquor suspended solids (MLSS) concentration X0. A new modified equation is proposed removing the dependency of the breakup coefficient to the initial value of X0 based on preliminary data using normal and low concentration mixed liquor suspended solids values in flocculation experiments performed.

Development and Validation of a 3-Dimensional Computational Fluid Dynamics (CFD) Model for Rectangular Settling Tanks in New York City Water Pollution Control Plants

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
K. Ramalingam ◽  
J. Fillos ◽  
S. Xanthos ◽  
M. Gong ◽  
A. Deur ◽  
...  
Keyword(s):  
Water Pollution ◽  
Fluid Dynamics ◽  
New York ◽  
Computational Fluid Dynamics ◽  
New York City ◽  
Pollution Control ◽  
York City ◽  
Three Dimensional ◽  
Cfd Model ◽  
Computational Fluid Dynamics Cfd

New York City provides secondary treatment to approximately 78.6 m3/s among its 14 water pollution control plants (WPCPs). The process of choice has been step-feed activated sludge. Changes to the permit limits require nitrogen removal in WPCPs discharging into the Long Island Sound. The City has selected step feed biological nitrogen removal (BNR) process to upgrade the affected plants. Step feed BNR requires increasing the concentration of mixed liquors, (MLSS), which stresses the Gould II type rectangular final settling tanks (FSTs). To assess performance and evaluate alternatives to improve efficiency of the FSTs at the higher loads, New York City Department of Environmental Protection (NYCDEP) and City College of New York (CCNY) have developed a three-dimensional computer model depicting the actual structural configuration of the tanks and the current and proposed hydraulic and solids loading rates. Using Computational Fluid Dynamics (CFD) Model, Fluent 6.3.26TM as the base platform, sub-models of the SS settling characteristics as well as turbulence, flocculation, etc. were incorporated. This was supplemented by field and bench scale experiments to quantify the co-efficients integral to the sub-models. As a result, a three-dimensional model has been developed that is being used to consider different baffle arrangements, sludge withdrawal mechanisms and loading alternatives to the FSTs.

Remembering Joseph A. Pechman, 1918–1989

1990 ◽  
Vol 4 (4) ◽  
pp. 121-124
Author(s):  
Henry J Aaron
Keyword(s):  
New York ◽  
World War Ii ◽  
World War ◽  
Brookings Institution ◽  
City College ◽  
University Of Wisconsin ◽  
Before And After ◽  
The University ◽  
The City ◽  
Treasury Department

Joe Pechman joined the staff of the Brookings Institution in 1960. He graduated from the City College of New York in 1937 and the University of Wisconsin in 1942. During World War II, he worked in the war time Office of Price Administration and later served in the U.S. Army. After the war he worked in the Treasury Department, the staff of the Council of Economic Advisers, and the Committee for Economic Development, a policy-oriented organization sponsored by major businesses. Before and after coming to Brookings he taught at M.I.T., Yale, Stanford (twice), Georgetown, Dartmouth, and Williams College. He was a fellow at the Center for Advanced Studies in the Behavioral Sciences and at the Hoover Institution, both at Stanford University.

Critical modeling parameters identified for 3D CFD modeling of rectangular final settling tanks for New York City wastewater treatment plants

2012 ◽  
Vol 65 (6) ◽  
pp. 1087-1094 ◽  
Author(s):  
K. Ramalingam ◽  
S. Xanthos ◽  
M. Gong ◽  
J. Fillos ◽  
K. Beckmann ◽  
...  
Keyword(s):  
New York ◽  
New York City ◽  
Wastewater Treatment ◽  
York City ◽  
Wastewater Treatment Plants ◽  
Settling Tank ◽  
Cfd Modeling ◽  
Cfd Model ◽  
Conventional Activated Sludge ◽  
City College

New York City Environmental Protection is in the process of incorporating biological nitrogen removal (BNR) in its wastewater treatment plants (WWTPs) which entails operating the aeration tanks with higher levels of mixed liquor suspended solids (MLSS) than a conventional activated sludge process. The objective of this paper is to discuss two of the important parameters introduced in the 3D CFD model that has been developed by the City College of New York (CCNY) group: (a) the development of the ‘discrete particle’ measurement technique to carry out the fractionation of the solids in the final settling tank (FST) which has critical implications in the prediction of the effluent quality; and (b) the modification of the floc aggregation (KA) and floc break-up (KB) coefficients that are found in Parker's flocculation equation (Parker et al. 1970, 1971) used in the CFD model. The dependence of these parameters on the predictions of the CFD model will be illustrated with simulation results on one of the FSTs at the 26th Ward WWTP in Brooklyn, NY.

Assessing the Wind-Heel Angle Relationship of Traditionally-Rigged Sailing Vessels

2009 ◽  
Author(s):  
William C. Lasher ◽  
Diana R. Tinlin ◽  
Bruce Johnson ◽  
John Womack ◽  
Jan C. Miles ◽  
...  
Keyword(s):  
Model Uncertainty ◽  
Significant Error ◽  
Future Research ◽  
Experimental Measurements ◽  
Cfd Model ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Computationally Expensive ◽  
Experimental Values ◽  
Relationship Of

A program to assess the wind-heel relationship of traditionally-rigged sailing vessels has been undertaken with the eventual goal of being able to provide sailing guidance to the masters and crews. This program uses Computational Fluid Dynamics (CFD) with full-scale experimental measurement to develop and validate a windheel model, as well as understand the nature of how these vessels respond to different wind situations. The CFD simulations are used to assess errors in measured wind angle and direction, and the experimental data are used to establish the CFD model uncertainty. The model has been validated against a limited set of data from Pride of Baltimore II. In some cases the agreement between the model and experimental values is excellent; in other cases there is significant error. The CFD-based model is computationally expensive, so a different approach for determining the sail forces is proposed. The experimental measurements indicate that the ship is almost never in static equilibrium, which raises questions about the validity of models based on equilibrium principles. These questions have not yet been answered and are the topic of ongoing future research.

Characterizing shallow secondary clarifier performance where conventional flux theory over-estimates allowable solids loading rate

2016 ◽  
Vol 74 (2) ◽  
pp. 324-332 ◽  
Author(s):  
Glen T. Daigger ◽  
John S. Siczka ◽  
Thomas F. Smith ◽  
David A. Frank ◽  
J. A. McCorquodale
Keyword(s):  
Suspended Solids ◽  
Loading Rate ◽  
Fluid Dynamic ◽  
Flux Analysis ◽  
Stress Tests ◽  
Mixed Liquor ◽  
Cfd Models ◽  
Solids Loading ◽  
Cfd Analyses ◽  
The City

The performance characteristics of relatively shallow (3.3 and 3.7 m sidewater depth in 30.5 m diameter) activated sludge secondary clarifiers were extensively evaluated during a 2-year testing program at the City of Akron Water Reclamation Facility (WRF), Ohio, USA. Testing included hydraulic and solids loading stress tests, and measurement of sludge characteristics (zone settling velocity (ZSV), dispersed and flocculated total suspended solids), and the results were used to calibrate computational fluid dynamic (CFD) models of the various clarifiers tested. The results demonstrated that good performance could be sustained at surface overflow rates in excess of 3 m/h, as long as the clarifier influent mixed liquor suspended solids (MLSS) concentration was controlled to below critical values. The limiting solids loading rate (SLR) was significantly lower than the value predicted by conventional solids flux analysis based on the measured ZSV/MLSS relationship. CFD analysis suggested that this resulted because mixed liquor entering the clarifier was being directed into the settled sludge blanket, diluting it and also creating a ‘thin’ concentration sludge blanket that overlays the thicker concentration sludge blanket typically expected. These results indicate the need to determine the allowable SLR for shallow clarifiers using approaches other than traditional solids flux analysis. A combination of actual testing and CFD analyses are demonstrated here to be effective in doing so.

Locating Al in the DABCO catalyst before and after Al extraction

1990 ◽  
Vol 48 (4) ◽  
pp. 265-267
Author(s):  
Kathleen B. Reuter
Keyword(s):  
Active Site ◽  
Inverse Relationship ◽  
Transverse Direction ◽  
Reaction Rate ◽  
Acid Phosphate ◽  
Fracture Surfaces ◽  
Al Content ◽  
Before And After ◽  
Relationship Of

The reaction rate and efficiency of piperazine to 1,4-diazabicyclo-octane (DABCO) depends on the Si/Al ratio of the MFI topology catalysts. The Al was shown to be the active site, however, in the Si/Al range of 30-200 the reaction rate increases as the Si/Al ratio increases. The objective of this work was to determine the location and concentration of Al to explain this inverse relationship of Al content with reaction rate.Two silicalite catalysts in the form of 1/16 inch SiO2/Al2O3 bonded extrudates were examined: catalyst A with a Si/Al of 83; and catalyst B, the acid/phosphate Al extracted form of catalyst A, with a Si/Al of 175. Five extrudates from each catalyst were fractured in the transverse direction and particles were obtained from the fracture surfaces near the center of the extrudate diameter. Particles were also obtained from the outside surfaces of five extrudates.

Book Reviews

2020 ◽  
Vol 8 (1) ◽  
pp. 209-228
Author(s):  
Martin Van Bruinessen ◽  
Michael M. Gunter ◽  
Joost Jongerden ◽  
Michiel Leezenberg ◽  
Stanley Thangaraj
Keyword(s):  
United States ◽  
New York ◽  
The Netherlands ◽  
Academic Publishing ◽  
Ethnic Cleansing ◽  
Cambridge University ◽  
City College ◽  
Tennessee Technological University ◽  
Technological University

Michael M. Gunter (ed.), Routledge Handbook on the Kurds, London and New York: Routledge, 2019, 483 pp., (ISBN: 9781138646643). Reviewed by Martin van Bruinessen, Utrecht University, The Netherlands Kardo Bokani, Social Communication and Kurdish Political Mobilisation in Turkey, Balti, Republic of Moldova: Lambert Academic Publishing, 2017, 252 pp., (ISBN: 978-3-330-33239-3) Reviewed by Michael M. Gunter, Tennessee Technological University, United States Emel Elif Tugdar & Serhun Al, eds., Comparative Kurdish Politics in the Middle East: Actors, Ideas, and Interests, Cham: Palgrave-MacMillan, 2018, pp. 235, (ISBN: 978-3319537146) Reviewed by Joost Jongerden, Wageningen University, The Netherlands Christoph Markiewicz, The Crisis of Kingship in Late Medieval Islam: Persian Emigres and the Making of Ottoman Sovereignty, Cambridge: Cambridge University Press, 2019, 364 pp, (9781108684842). Reviewed by Michiel Leezenberg, University of Amsterdam, The Netherlands Thomas Schmidinger, The Battle for the Mountain of the Kurds: Self-Determination and Ethnic Cleansing in the Afrin Region of Rojava, Oakland, CA: PM Press, 2019, 192 pp. (ISBN: 978-1629636511). Reviewed by Stanley Thangaraj, City College of New York, United States

Effects of Over Fire Air on the Combustion and NOx Emission Characteristics of a 600 MW Opposed Swirling Fired Boiler

2012 ◽  
Vol 512-515 ◽  
pp. 2135-2142 ◽  
Author(s):  
Yu Peng Wu ◽  
Zhi Yong Wen ◽  
Yue Liang Shen ◽  
Qing Yan Fang ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Empirical Method ◽  
Nox Emission ◽  
Emission Characteristics ◽  
Cfd Model ◽  
Nitrogen Release ◽  
Computational Fluid Dynamics Cfd ◽  
Low Nox Emission

A computational fluid dynamics (CFD) model of a 600 MW opposed swirling coal-fired utility boiler has been established. The chemical percolation devolatilization (CPD) model, instead of an empirical method, has been adapted to predict the nitrogen release during the devolatilization. The current CFD model has been validated by comparing the simulated results with the experimental data obtained from the boiler for case study. The validated CFD model is then applied to study the effects of ratio of over fire air (OFA) on the combustion and nitrogen oxides (NOx) emission characteristics. It is found that, with increasing the ratio of OFA, the carbon content in fly ash increases linearly, and the NOx emission reduces largely. The OFA ratio of 30% is optimal for both high burnout of pulverized coal and low NOx emission. The present study provides helpful information for understanding and optimizing the combustion of the studied boiler

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