scholarly journals Effect of Porous Baffles on the Energy Performance of Contact Tanks in Water Treatment

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1084 ◽  
Author(s):  
M. A. Kizilaslan ◽  
E. Demirel ◽  
M. M. Aral
Keyword(s):  
Energy Efficiency ◽  
Water Treatment ◽  
Porous Layer ◽  
Hydraulic Efficiency ◽  
Tracer Transport ◽  
Dispersion Effects ◽  
Conventional Design ◽  
Flow Through ◽  
Contact Tanks ◽  
Porous Zone

Three-dimensional numerical simulations are performed to evaluate the effect of porous baffles on the efficiency of water treatment contact tanks. A second-order accurate numerical model is employed for the solutions of unsteady flow and tracer transport through the porous baffles. The flow through the porous medium is characterized while using the Darcy-Forchheimer relationship. Large Eddy Simulation (LES) model is used to simulate the instantaneous mixing of the tracer in the chambers of the contact tank. Three different porosities are considered to evaluate the effect of porosity on the hydraulic and mixing efficiencies of the contact tank. Simulated time-averaged flow field shows that porous baffles that are placed at the entrance of each chamber could successfully mitigate short-circuiting and yield plug-flow conditions through the system for low porosities. Flow in the contact tank becomes laminar as the flow velocities decrease due to viscous effects and inertial resistance in the porous zone. For this case, the tracer is transported with bulk flow through the system and leaves the contact tank with a high peak seen in the Residence Time Distribution (RTD) plot. Porous layer increases the hydraulic efficiency of the conventional design from “poor” to “good” according to the baffling factor and increases the overall efficiency from “compromising” to “good” according to the AD index. Comparison of the performance of the porous layer with the previously developed slot-baffle design shows that the slot-baffle design increases the efficiency of the tank with increasing dispersion effects, whereas the porous design increases hydraulic efficiency and reduces the dispersion effects. While the porous design reduces energy efficiency by 33% due to a drastic increase in drag in the flow through porous zone, the slot-baffle design increases the energy efficiency of the conventional design by 67%.

STABILITY OF COUPLE STRESS FLUID FLOW THROUGH A HORIZONTAL POROUS LAYER

2016 ◽  
Vol 19 (5) ◽  
pp. 391-404 ◽  
Author(s):  
B. M. Shankar ◽  
I. S. Shivakumara ◽  
Chiu-On Ng
Keyword(s):  
Fluid Flow ◽  
Porous Layer ◽  
Couple Stress ◽  
Couple Stress Fluid ◽  
Flow Through

scholarly journals Phosphate and Ammonium Removal from Water through Electrochemical and Chemical Precipitation of Struvite

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 150
Author(s):  
Kyösti Rajaniemi ◽  
Tao Hu ◽  
Emma-Tuulia Nurmesniemi ◽  
Sari Tuomikoski ◽  
Ulla Lassi
Keyword(s):  
Energy Efficiency ◽  
Water Treatment ◽  
Chemical Precipitation ◽  
Phosphate Removal ◽  
Nutrient Recovery ◽  
Ammonium Removal ◽  
Synthetic Water

Batch electrocoagulation (BEC), continuous electrocoagulation (CEC), and chemical precipitation (CP) were compared in struvite (MgNH4PO4·6H2O) precipitation from synthetic and authentic water. In synthetic water treatment (SWT), struvite yield was in BEC 1.72, CEC 0.61, and CP 1.54 kg/m3. Corresponding values in authentic water treatment (AWT) were 2.55, 3.04, and 2.47 kg/m3. In SWT, 1 kg struvite costs in BEC, CEC, and CP were 0.55, 0.55, and 0.11 €, respectively, for AWT 0.35, 0.22 and 0.07 €. Phosphate removal in SWT was 93.6, 74.5, and 71.6% in BEC, CEC, and CP, respectively, the corresponding rates in AWT were 89.7, 77.8, and 74.4%. Ammonium removal for SWT in BEC, CEC, and CP were 79.4, 51.5, and 62.5%, respectively, rates in AWT 56.1, 64.1, and 60.9%. Efficiency in CEC and BEC are equal in nutrient recovery in SWT, although energy efficiency was better in CEC. CP is cheaper than BEC and CEC.

scholarly journals Squeeze Flow of Bingham Fluids through Reticulated, Compressed Foams

Lubricants ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 86
Author(s):  
Turtoi ◽  
Pascovici ◽  
Cicone
Keyword(s):  
Porous Layer ◽  
Normal Force ◽  
Central Zone ◽  
Squeeze Flow ◽  
High Plasticity ◽  
High Porosity ◽  
Viscoplastic Material ◽  
Shock Absorbers ◽  
Flow Through ◽  
Original Approach

The paper presents experimental and theoretical results for the planar squeeze flow of a finite volume of viscoplastic material through a highly deformable porous layer. The central zone of an annular disc made of a reticulated polyurethane foam with high porosity (ε > 0.97) was fully filled with tooth paste. The porous disc placed between two flat, impermeable, parallel, and rigid discs was subjected to compression and the normal force was recorded. After compression, the radial extension of the squeezed fluid was measured. The visualisation of the compressed disc managed to provide evidence of a tortuous flow inside the porous structure. An original analytical model is proposed for the prediction of the front of the flow inside the porous layer and corresponding resistant normal force. The model combines the Covey and Stanmore (1981) model for squeeze flow of a Bingham fluid inside the central zone, with an original approach for flow through the reticulated foams, based on the concept of “equivalent flow tubes” with variable tortuosity. This explorative investigation is of interest for innovative shock absorbers. The model validity covers both low and high plasticity numbers and was experimentally validated for low speed.

scholarly journals Designing a robust index for WWTP energy efficiency: The ENERWATER water treatment energy index

2020 ◽  
Vol 713 ◽  
pp. 136642 ◽  
Author(s):  
Miguel Mauricio-Iglesias ◽  
Stefano Longo ◽  
Almudena Hospido
Keyword(s):  
Energy Efficiency ◽  
Water Treatment ◽  
Energy Index

Micropolar fluid flow through the membrane composed of impermeable cylindrical particles coated by porous layer under the effect of magnetic field

2019 ◽  
Vol 43 (4) ◽  
pp. 1925-1937 ◽  
Author(s):  
Pramod Kumar Yadav ◽  
Sneha Jaiswal ◽  
Jaikanth Yadav Puchakatla
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Porous Layer ◽  
Micropolar Fluid ◽  
Micropolar Fluid Flow ◽  
Flow Through ◽  
Cylindrical Particles

scholarly journals Energy-Efficient Coding with Discrete Stochastic Events

2002 ◽  
Vol 14 (6) ◽  
pp. 1323-1346 ◽  
Author(s):  
Susanne Schreiber ◽  
Christian K. Machens ◽  
Andreas. V. M. Herz ◽  
Simon B. Laughlin
Keyword(s):  
Energy Efficiency ◽  
Energy Efficient ◽  
Information Transfer ◽  
Energy Use ◽  
Bimodal Distribution ◽  
Fixed Cost ◽  
Signaling Cost ◽  
Trade Offs ◽  
Flow Through ◽  
Stochastic Events

We investigate the energy efficiency of signaling mechanisms that transfer information by means of discrete stochastic events, such as the opening or closing of an ion channel. Using a simple model for the generation of graded electrical signals by sodium and potassium channels, we find optimum numbers of channels that maximize energy efficiency. The optima depend on several factors: the relative magnitudes of the signaling cost (current flow through channels), the fixed cost of maintaining the system, the reliability of the input, additional sources of noise, and the relative costs of upstream and downstream mechanisms. We also analyze how the statistics of input signals influence energy efficiency. We find that energy-efficient signal ensembles favor a bimodal distribution of channel activations and contain only a very small fraction of large inputs when energy is scarce. We conclude that when energy use is a significant constraint, trade-offs between information transfer and energy can strongly influence the number of signaling molecules and synapses used by neurons and the manner in which these mechanisms represent information.

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