Study on two operating conditions of a full-scale oxidation ditch for optimization of energy consumption and effluent quality by using CFD model

2011 ◽  
Vol 45 (11) ◽  
pp. 3439-3452 ◽  
Author(s):  
Yin Yang ◽  
Jiakuan Yang ◽  
Jiaolan Zuo ◽  
Ye Li ◽  
Shu He ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Full Scale ◽  
Operating Conditions ◽  
Oxidation Ditch ◽  
Cfd Model ◽  
Effluent Quality

A Critical Look into the Deviation of Full Scale Performance from Design Expectations

1989 ◽  
Vol 21 (10-11) ◽  
pp. 1389-1402 ◽  
Author(s):  
R. Zaloum
Keyword(s):  
Expert Systems ◽  
Waste Treatment ◽  
Full Scale ◽  
Operating Conditions ◽  
Organic Load ◽  
Computer Assisted ◽  
Uniform Load ◽  
Effluent Quality ◽  
Simulation Techniques ◽  
Steady Level

Deviations from design expectations appear to stem from views which assume that a unique response should result from a given set of operating conditions. The results of this study showed that two systems operating at equal organic loads or F/M ratios and at the same SRT do not necessarily give equal responses. This deviation was linked to the manner in which the HRT and influent COD are manipulated to obtain a constant or uniform load, and to subtle interactions between influent COD, HRT and SRT on the biomass and effluent responses. Increases of up to 200% in influent COD from one steady level to the next did not significantly influence the effluent VSS concentration while an effect on filtered COD was observed for increases as low as 20%. Effluent TKN and filtered COD correlated strongly with the operating MLVSS while phosphorus residual depended on the operating SRT and the organic load removed. These results point to the inadequacy of traditional models to predict effluent quality and point to the need to consider these effects when developing simulation techniques or computer assisted expert systems for the control of waste treatment plants.

Reliability analysis of stabilisation pond systems

2007 ◽  
Vol 55 (11) ◽  
pp. 127-134 ◽  
Author(s):  
S.M.A.C. Oliveira ◽  
M. von Sperling
Keyword(s):  
Reliability Analysis ◽  
Coefficient Of Variation ◽  
High Variability ◽  
Full Scale ◽  
Operating Conditions ◽  
Effluent Quality ◽  
Standard Values ◽  
Expected Compliance

This article presents a reliability analysis of 116 full-scale pond systems in Brazil, comprising 73 primary facultative ponds and 43 anaerobic–facultative pond systems. A methodology developed by Niku et al. (1979) is used for the determination of the coefficients of reliability, in terms of the compliance of effluent BOD, COD, TSS and FC to discharge standards or effluent quality targets. The design concentrations necessary to meet the prevailing discharge standards and the expected compliance percentages have been calculated from the coefficients of reliability obtained. The results showed that few units, under the observed operating conditions, would be able to present reliable performances in terms of compliance with the analyzed standards. For the four constituents (BOD, COD, TSS and FC) and both systems (facultative ponds and anaerobic-facultative systems), the variability of the effluent quality was very large, leading to a high variability of the coefficient of variation (CV) and the coefficient of reliability (COR). The effluent quality from the facultative ponds showed a larger distance to both the desired values and the discharge standard values, compared with the anaerobic–facultative systems.

Design and operating experiences of municipal MBRs in Europe

2008 ◽  
Vol 58 (12) ◽  
pp. 2319-2327 ◽  
Author(s):  
H. Itokawa ◽  
C. Thiemig ◽  
J. Pinnekamp
Keyword(s):  
Membrane Bioreactor ◽  
Membrane Damage ◽  
Full Scale ◽  
Operating Conditions ◽  
Small Scale ◽  
Membrane Unit ◽  
Effluent Quality ◽  
Membrane Flux ◽  
The Moment ◽  
And Control

The number of membrane bioreactor (MBR) installations is increasing worldwide, not only for small-scale industrial WWTPs but also for larger-scale municipal WWTPs. In Europe, MBR has been installed in municipal WWTPs since late 1990s, and more than 100 full-scale plants are operated at the moment. In this paper, present state of European municipal MBRs is described in terms of design and operating conditions, as well as operating problems and their solutions, based on the information collected from 17 full-scale WWTPs by interview and questionnaire survey. Decisive factors of MBR installation at these plants were footprint and effluent quality. Full-aerobic and pre-denitrification were the most common reactor configurations, nearly half of them being equipped with independent filtration tanks. Operating conditions of bioreactor and filtration, including membrane flux and cleaning strategy, were different from plant to plant, as a result of plant-specific optimization experiences, even among the similar type of membrane. Operating problems specific for MBR were reported, including blocking/failure of pre-screen, sludging/hair-clogging of membrane, damage on membrane unit, air in permeate pipes, as well as conventional troubles including occurrence of scum and initial trouble in instrumentation and control systems. Aspects for further optimization of MBR design were also pointed out by the operators.

Optimization design of submerged propeller in oxidation ditch by computational fluid dynamics and comparison with experiments

2016 ◽  
Vol 74 (3) ◽  
pp. 681-690 ◽  
Author(s):  
Yuquan Zhang ◽  
Yuan Zheng ◽  
E. Fernandez-Rodriguez ◽  
Chunxia Yang ◽  
Yantao Zhu ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Consumption ◽  
Flow Field ◽  
Flow Pattern ◽  
Operating Conditions ◽  
Oxidation Ditch ◽  
Actual Measurement ◽  
Operating Condition ◽  
Rotating Speed

The operating condition of a submerged propeller has a significant impact on flow field and energy consumption of the oxidation ditch. An experimentally validated numerical model, based on the computational fluid dynamics (CFD) tool, is presented to optimize the operating condition by considering two important factors: flow field and energy consumption. Performance demonstration and comparison of different operating conditions were carried out in a Carrousel oxidation ditch at the Yingtang wastewater treatment plants in Anhui Province, China. By adjusting the position and rotating speed together with the number of submerged propellers, problems of sludge deposit and the low velocity in the bend could be solved in a most cost-effective way. The simulated results were acceptable compared with the experimental data and the following results were obtained. The CFD model characterized flow pattern and energy consumption in the full-scale oxidation ditch. The predicted flow field values were within −1.28 ± 7.14% difference from the measured values. By determining three sets of propellers under the rotating speed of 6.50 rad/s with one located 5 m from the first curved wall, after numerical simulation and actual measurement, not only the least power density but also the requirement of the flow pattern could be realized.

scholarly journals Modelling Mechanically Induced Non-Newtonian Flows to Improve the Energy Efficiency of Anaerobic Digesters

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2995
Author(s):  
Andrew Oates ◽  
Thomas Neuner ◽  
Michael Meister ◽  
Duncan Borman ◽  
Miller Camargo-Valero ◽  
...  
Keyword(s):  
Power Consumption ◽  
Anaerobic Digester ◽  
Full Scale ◽  
Operating Conditions ◽  
Cfd Model ◽  
Total Solids ◽  
Helical Ribbon ◽  
Newtonian Flows ◽  
Solids Concentration ◽  
Water Glycerol

In this paper, a finite volume based computational fluid dynamics (CFD) model has been developed for investigating the mixing of non-Newtonian flows and operating conditions of an anaerobic digester. A CFD model using the multiple reference frame has been implemented in order to model the mixing in an anaerobic digester. Two different agitator designs have been implemented: a design currently used in a full-scale anaerobic mixing device, SCABA, and an alternative helical ribbon design. Lab-scale experiments have been conducted with these two mixing device designs using a water-glycerol mixture to replicate a slurry with total solids concentration of 7.5%, which have been used to validate the CFD model. The CFD model has then been scaled up in order to replicate a full-scale anaerobic digester under real operating parameters that is mechanically stirred with the SCABA design. The influence of the non-Newtonian behaviour has been investigated and found to be important for the power demand calculation. Furthermore, the other helical mixing device has been implemented at full scale and a case study comparing the two agitators has been performed; assessing the mixing capabilities and power consumption of the two designs. It was found that, for a total solids concentrations of 7.5%, the helical design could produce similar mixing capabilities as the SCABA design at a lower power consumption. Finally, the potential power savings of the more energy efficient helical design has been estimated if implemented across the whole of the United Kingdom (UK)/Austria.

Nitrogen Removal in an Oxidation Ditch with Intermittent Aeration

1987 ◽  
Vol 19 (1-2) ◽  
pp. 209-218 ◽  
Author(s):  
Katsuto Inomae ◽  
Hiroyuki Araki ◽  
Kenichi Koga ◽  
Youichi Awaya ◽  
Tetsuya Kusuda ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Carbon Sources ◽  
Full Scale ◽  
Operating Conditions ◽  
High Rate ◽  
Oxidation Ditch ◽  
Intermittent Aeration ◽  
Plant System ◽  
Anoxic Zones ◽  
Typical Process

The typical process of nitrogen removal in the oxidation ditch is achieved through the control of oxygen supply ( forming aerobic and anoxic zones within the ditch channel) or alternating aeration using intermittently operating aerator(s). The operating conditions for efficient nitrogen removal with any of these methods have yet to be clarified. The purpose of this study is to establish an oxidation ditch system with a high rate of nitrogen removal by intermittent aeration. Effects of intermittent aeration on nitrogen removal characteristics were studied by experiments with a bench scale- and full scale-plant and by simulation. The conditions of optimum operation (aerobic and anoxic periods) for a high rate of nitrogen removal were found. These conditions principally depend upon the rates of nitrification and denitrification. By operating the full scale plant system with intermittent aeration ( cycle time is 45 minutes and aerobic ratio is 0.42 ), a high rate nitrogen removal efficiency of 81% was achieved without adding any alkaline matter or organic carbon sources. It was shown that the results of simulation agree with the observed data of the full scale plant system, and that the rate of denitrification depends upon the conditions of intermittent aeration.

Simulation of flow field and sludge settling in a full-scale oxidation ditch by using a two-phase flow CFD model

2014 ◽  
Vol 109 ◽  
pp. 296-305 ◽  
Author(s):  
Hao Xie ◽  
Jiakuan Yang ◽  
Yuchen Hu ◽  
Hao Zhang ◽  
Yin Yang ◽  
...  
Keyword(s):  
Flow Field ◽  
Two Phase Flow ◽  
Full Scale ◽  
Phase Flow ◽  
Oxidation Ditch ◽  
Cfd Model ◽  
Two Phase ◽  
Sludge Settling

Multidimensional Numerical Modeling of Combustion Dynamics in a Non-Premixed Rotating Detonation Engine with Adaptive Mesh Refinement

2021 ◽  
pp. 1-32
Author(s):  
Pinaki Pal ◽  
Gaurav Kumar ◽  
Scott Drennan ◽  
Brent Rankin ◽  
Sibendu Som
Keyword(s):  
Performance Optimization ◽  
Adaptive Mesh Refinement ◽  
Design Space Exploration ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Full Scale ◽  
Operating Conditions ◽  
Cfd Model ◽  
Combustion Dynamics ◽  
Frequency Wave

Abstract In the present work, a novel computational fluid dynamics (CFD) methodology was developed to simulate full-scale non-premixed RDEs. A unique feature of the modeling approach was incorporation of adaptive mesh refinement (AMR) to achieve good trade-off between model accuracy and computational expense. Unsteady Reynolds-Averaged Navier-Stokes (RANS) simulations were performed for an Air Force Research Laboratory (AFRL) non-premixed RDE configuration with hydrogen as fuel and air as the oxidizer. The finite-rate chemistry model along with a 10-species detailed kinetic mechanism were employed to describe the H2-Air combustion chemistry. Three distinct operating conditions were simulated, corresponding to the same global equivalence ratio of unity but different fuel/air mass flow rates. For all conditions, the capability of the model to capture essential detonation wave dynamics was assessed. An exhaustive verification and validation study was performed against experimental data in terms of number of waves, wave frequency, wave height, reactant fill height, oblique shock angle, axial pressure distribution in the channel, and fuel/air plenum pressure. The CFD model was demonstrated to accurately predict the sensitivity of these wave characteristics to the operating conditions, both qualitatively and quantitatively. A comprehensive heat release analysis was conducted to quantify detonative versus deflagrative burning for the three simulated cases. The present CFD model offers a potential capability to perform rapid design space exploration and/or performance optimization studies for realistic full-scale RDE configurations.

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