| 1. |
- Haque, Nazmul, et al.
(författare)
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Characteristics of arsenic adsorption to sorghum biomass
- 2007
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 1873-3336 .- 0304-3894. ; 145:1-2, s. 30-35
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Tidskriftsartikel (refereegranskat)abstract
- The development of efficient and economic new adsorbent materials for the removal of arsenic from groundwater is a priority in regions where human health is directly affected by elevated arsenic concentrations. Adsorption of arsenic on sorghum biomass (SB) was investigated for the removal of arsenic from aqueous solutions. Potentiometric titrations and FTIR analysis evidenced two potential binding sites associated with carboxyl and hydroxyl groups. Batch experiments were carried out to determine the equilibrium time for arsenic adsorption to SB. The effect of pH on arsenic adsorption to SB was investigated for a pH range of 2.0-10.0. A strong influence of pH was demonstrated with a maximum removal of arsenic at pH 5.0. Freundlich and Langmuir isotherms were applied to equilibrium data. The Freundlich model fitted the equilibrium data and provided evidence for site heterogeneity at the binding surface. Column experiments were performed to obtain the breakthrough curves for both non-immobilized sorghum biomass and immobilized sorghum biomass.
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| 2. |
- Haque, Nazmul, et al.
(författare)
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Sorption of arsenic on sorghum biomass: a case study
- 2005
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Ingår i: Natural Arsenic in Groundwater. - : CRC Press. - 9780415367004 ; , s. 247-253
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Large scale, field experiments were conducted for the removal of arsenic from the groundwater of a well located in Guanajuato, Mexico region using non-immobilized sorghum biomass (NISB) as a sorbent, which was found highly efficient to adsorb As in previous laboratory experiments. The columns were run under gravity and pump flow conditions. Removal of arsenic under pump flow was slightly higher than the gravity flow due to the steady-state flow conditions. The maximum arsenic accumulation measured was 3.2 and 3.3 mg of As/g of NISB for gravity and pump flow conditions, respectively. To determine the optimal hydraulic detention time, columns were operated under different flow rates and the maximum sorption occurred at a flow rate of 10 mL/min. Columns of different dimensions were run to obtain the optimal design parameter between surface loading and volumetric loading of the system. The optimal sorption condition can be achieved through the volumetric design of the system.
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| 3. |
- Mark, O., et al.
(författare)
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Prediction of locations with sediment deposits in sewers
- 1996
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Ingår i: Water Science and Technology. - : IWA Publishing. - 1996-9732 .- 0273-1223. ; 33:9, s. 147-154
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Tidskriftsartikel (refereegranskat)abstract
- The present paper presents an application of MOUSE ST, a general deterministic sediment transport model for sewer systems. MOUSE ST is used to predict the locations subjected to sedimentation in the sewer system of Ljubljana, Slovenia. The prediction is made by means of a sediment transport model with a movable bed. This model is run in parallel with the hydrodynamic MOUSE model. The results, in terms of locations with sediment deposits, are compared with field data from the sewer system in Ljubljana. Further, the model is used to predict the effect of the removal of the sediment deposits on the combined sewer overflows. The present paper presents an application of MOUSE ST, a general deterministic sediment transport model for sewer systems. MOUSE ST is used to predict the locations subjected to sedimentation in the sewer system of Ljubljana, Slovenia. The prediction is made by means of a sediment transport model with a movable bed. This model is run in parallel with the hydrodynamic MOUSE model. The results, in terms of locations with sediment deposits, are compared with field data from the sewer system in Ljubljana. Further, the model is used to predict the effect of the removal of the sediment deposits on the combined sewer overflows.
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| 4. |
- Ota, J. J., et al.
(författare)
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Particle velocity and sediment transport at the limit of deposition in sewers
- 2013
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Ingår i: Water Science and Technology. - : IWA Publishing. - 1996-9732 .- 0273-1223. ; 67:5, s. 959-967
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on the sediment particle while it is transported at the limit of deposition in storm sewers, i.e. as bed load at the limit of concentration that leads to sediment deposition. Although many empirical sediment transport equations are known in the literature, there is only limited knowledge concerning particle velocity. Sediment particle and sphere velocity measurements were carried out in two pipe channels and these results led to the development of a semi-theoretical equation for sediment transport at the limit of deposition in sewers. Even in the transport process without deposition, sediment movement is slower than water velocity and depends on the angle of repose of sediment with a diameter d on the roughness k of the pipe channel. Instead of classical dimensionless bed shear stress psi, a modified dimensionless bed shear stress psi(d/k)(2/3) was suggested, based on the angle of repose and this parameter was proved to be significant for quantifying the transport capacity. The main purpose of this article is to emphasize the importance of careful observation of experiments. Not only number of tests, but physical understanding are essential for better empirical equations.
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| 5. |
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| 6. |
- Perrusquía, Gustavo, 1954
(författare)
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An Experimental Study on the Transport of Sediment in Sewer Pipes with a Permanent Deposit
- 1992
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Ingår i: Water Science and Technology. - : IWA Publishing. - 1996-9732 .- 0273-1223. ; 25:8, s. 115-122
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Tidskriftsartikel (refereegranskat)abstract
- An experimental study of the transport of sediment in a part-full pipe was carried out in a concrete pipe. The experiments were confined to bedload transport. The purpose of this study was to analyze the flow conditions that characterize the stream traction in pipe channels and their relationship to flow resistance and sediment transport rate. Three procedures used in this kind of experimental study were tested and found valid: 1) the vertical velocity distribution near the sediment bed can be described by the velocity-defect law, 2) the side wall elimination procedure can be used to compute the hydraulic radius of the sediment bed, and 3) the critical shear stress of the sediment particles can be obtained by using Shields' diagram. A relationship to estimate bedload transport, based on dimensional analysis, was proposed. This was expressed in terms of both flow and particle parameters as well as geometric factors. Further experimental work is recommended before this relationship can be fully incorporated in a simulation model for the analysis of storm sewers.
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| 7. |
- Perrusquía, Gustavo, 1954, et al.
(författare)
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Bedload transport in pipe channels
- 1996
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Ingår i: Journal of Hydrology and Hydromechanics. ; 44:1, s. 12-23
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Tidskriftsartikel (refereegranskat)abstract
- Six series of experimental results on bedload transport in pipe channels with deposited alluvial bed were collected. The observed values were compared with existing formulae for the description of sediment transport in alluvial channels. It was shown that a relationship as simple as those based on one or two parameters is not sufficient for the description of bedload transport in pipe channels and a new relationship for the estimation of this type of transport, based on dimensional analysis, was proposed using 66 observations. The new relationship was verified using the remaining 95 observations and finally modified to cover all 161 observations. With the inclusion of the shape factory B/Y the effectiveness of this relationship was improved.
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| 8. |
- Perrusquía, Gustavo, 1954
(författare)
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Bedload transport in storm sewers
- 1991
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Ingår i: Proc. First international workshop on origin, occurrence and behaviour of sediments in sewer systems.
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Konferensbidrag (refereegranskat)
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| 9. |
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| 10. |
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