Effect of sorption process on cadmium transport

Mahdavi, Ali; Kashefipour, S. M.; Omid, M H

doi:10.1680/wama.11.00040

Cited by 10 publications

(16 citation statements)

References 25 publications

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“…where, C0 is the initial cadmium concentration (t = 0) and C is the cadmium concentration at different times (ppb), Ɐ is the volume of the water (130 lit), and W is the weight of the sediments (gr). For the kinetic modeling, a pseudo second order equation is used (Ho and McKay 1999;Azizian 2004;and Mahdavi et al 2013), as follows:…”

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confidence: 99%

Experimental and Numerical Investigation of Effect of Cadmium Sorption by River Sediments on Longitudinal Dispersion

Nasrabadi

Mazdeh

Omid

2021

Preprint

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This paper concerns the cadmium sorptive effects by river bed sediments on longitudinal coefficient in an open-channel flow via experimental and numerical study. For this purpose, a circular flume was used with mean diameter of 1.6 m and a width of 0.2 m. The adsorbing bed was considered as a thin layer of the sediment particles with mean diameter of 0.5 mm and three sediment concentrations of 3, 12, and 20 gr/lit. To determine the sorption parameters of the sediments, some experiments were conducted with three cadmium concentrations of 150, 460, and 770 ppb. Then, the dispersion experiments were carried out with and without the bed sediments. To solve the advection-dispersion equation with considering the sorption term by river bed sediments, a numerical model was then developed. The longitudinal dispersion coefficients were estimated by comparing the experimental and numerical breakthrough curves. The results showed that, with increasing the sediment concentrations, the sediment sorption rate increased and the longitudinal dispersion coefficient decreased by about 38, 36 and 33 percent, respectively, for cadmium concentrations of 150, 460 and 770 ppb. In addition, by increasing the cadmium concentrations, the changes in the longitudinal dispersion coefficient are decreased. Furthermore, a relationship was developed using non-dimensional longitudinal dispersion as a function of the new parameter of sorption ratio. From a practical point of view, the results of this study demonstrated that, at the presence of sediment, the cadmium is longitudinally dispersed with more delay in comparison with no sediment at the river bed.

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confidence: 99%

Experimental and Numerical Investigation of Effect of Cadmium Sorption by River Sediments on Longitudinal Dispersion

Nasrabadi

Mazdeh

Omid

2021

Preprint

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“…Ng (2000), Wu et al (2005) and Mahdavi et al (2009) concluded that phase exchange, including adsorption and detachment, would occur between both parts, indicating the significant role of sediment particles in transport transformation processes. As an example, in experimental work conducted by Mahdavi et al (2012), it was observed that the presence of bed load materials would result in a 20% decrease in dispersion coefficient.…”

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confidence: 99%

“…However, in TST experiments the advection parameter, which is a key factor in sediment and pollutant transport, is ignored; consequently, this technique does not offer a fair simulation of the natural conditions. In this regard, Mahdavi et al (2009Mahdavi et al ( , 2012 proposed a circular flume to better simulate natural conditions. This work paved a path towards a comparison of results taken from reactors and natural rivers with bed load movement.…”

Section: Introductionmentioning

confidence: 99%

“…This work paved a path towards a comparison of results taken from reactors and natural rivers with bed load movement. Mahdavi et al (2009Mahdavi et al ( , 2012 showed that the type of movement is ineffective in terms of ultimate adsorption but it significantly influences the time needed to achieve the equilibrium state. The work employed limited experiments and lacked suspended load, which could play an important role in the adsorption of polluting materials compared with bed loads.…”

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confidence: 99%

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The effect of sediment motion on adsorption of cadmium

Ghoveisi¹,

Mazdeh²,

Frounchi³

et al. 2014

Proceedings of the Institution of Civil Engineers - Water Manag

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This paper describes the results of experimental work in a circular flume and a reactor device to show the role and importance of flow velocity, sediment movement type and concentration in the kinetic adsorption and transport of cadmium in both bed and suspended load conditions. The results show that the rate of adsorption is directly connected with sediment motion type and flow velocity. Considering a specific sediment concentration for the bed load condition, it was observed that the equilibrium capacity increased by 20% as the flow velocity changed from 0 . 35 to 0 . 7 m/s. Moreover, the use of batch reactors overestimates sorption capacity. However, for suspended load conditions, the equilibrium capacity was not significantly affected by the flow velocity or sediment motion type (comparing flume and batch reactor results). It was experimentally deduced that increasing the sediment concentration load by 300% would decrease the equilibrium cadmium adsorption in unit mass by 170% and 250% for bed and suspended loads respectively. Notation C 0 concentration of solution at t ¼ 0 (ìg/l) C t concentration of solution at t ¼ t (ìg/l) k rate of adsorption (1/s) k 1 constant for first order of adsorption rate (1/s) k 2 constant for second order of adsorption rate (1/s) q e amount of cadmium adsorbed per unit mass of sediment at equilibrium state (ìg/g) q t amount of cadmium adsorbed per unit mass of sediment at time t (ìg/g) V volume of water (l) W mass of sediment (g)

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“…Sediment transport also plays an important role in pollutant transport. Mahdavi et al (2013) investigate sorption of cadmium in sediment, transport of cadmium with sediment and desorption back into the water. An experimental setup with a circular flume simulating river flow was applied for modelling adsorption of cadmium in sediment.…”

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Editorial

Marenče¹

2013

Proceedings of the Institution of Civil Engineers - Water Manag

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By the end of the nineteenth century the first hydraulic laboratories had been established, mostly in the current technical universities. Physical modelling allows insight into the complex interactions between water flow and hydraulic structures. Hydraulic physical modelling became an effective support tool in solving complex hydraulic problems. Results from model tests acted as a driving force for further theoretical developments of analytical and later also numerical methods. Today the development of mathematical models and numerical simulations, as a cheaper and faster approach, decreases the significance of hydraulic laboratory tests but cannot fully substitute for physical modelling. Physical modelling is still used in solving very complex problems and in the verification of new developed mathematical and numerical models. Mathematical models often need input parameters that can only be determined through physical modelling. Therefore, both physical modelling in hydraulic laboratories and mathematical and numerical models are complement and irreplaceable in practical design and research work in hydraulic engineering today. This issue of Water Management illustrates the implementation of experimental and numerical methods and their combinations in solving typical hydraulic problems.Two papers in this issue discuss local scour around bridge piers, including interference of water flow, structure and river bed sediments. Local scour is often a reason for bridge collapse and is therefore also a topic with great public interest. The problem of scouring is a complex topic dependent on a large number of parameters. These different parameters are discussed in the first two papers.The paper by Chreties et al. (2013) presents the influence of flow conditions on local scour around pier groups. The authors chose physical modelling and concentrate their research on equilibrium scour depth with 'no memory' effect -scour depth does not depend on the flow conditions used to obtain the actual scour state. The results confirm that sediment characteristics are the most dominant factor defining form and depth of the scour hole.The experimental results also demonstrate that the 'no memory' hypothesis is valid for pier groups where the pier cap does not interfere with the flow.The second scour paper (Dehghani et al., 2013) is a detailed study of scouring around bridge piers under unsteady flow conditions. The authors chose to use a three-dimensional numerical model, combining Navier-Stokes equations and the sediment continuity equation. In the study, stepwise defined hydrographs with different peak discharges and period shapes were used, simulating timedependent scour development around a circular pier. The suggested numerical procedure provides good agreement with scour depth measured in the experiment and could be applied to assess scour development in real flood, unsteady state, conditions. The paper by Wallerstein and Arthur (2013) deals with the estimation of trash screen blockage by organic and manmade debris. More than 100...

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Effect of sorption process on cadmium transport

Cited by 10 publications

References 25 publications

Experimental and Numerical Investigation of Effect of Cadmium Sorption by River Sediments on Longitudinal Dispersion

Experimental and Numerical Investigation of Effect of Cadmium Sorption by River Sediments on Longitudinal Dispersion

The effect of sediment motion on adsorption of cadmium

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