Personal Research Database

Full Text: W\Wat Air Soi Pol150, 235.pdf

Abstract: Biological processes can achieve nitrate removal from groundwater. The sulfur/limestone autotrophic denitrification by Thiobacillus denitrificans was evaluated with three laboratory-scale column reactors. The optimum sulfur/limestone ratio was determined to be 2: 1 (mass/mass). Different hydraulic retention times were used during the column tests to examine nitrate removal efficiencies. Under an HRTs of 13 h, nitrate concentration of 60 mg NO₃-N L^-1 was reduced to less than 5 mg NO₃-N L^-1. On a higher HRT of 26 h the nitrate removal efficiency was close to 100% for all nitrate-nitrogen loading rates. Different initial nitrate-nitrogen concentrations (30, 60, and 90 mg NO₃-N L^-1) were used in the study. Column tests showed that the nitrate-nitrogen loading rate in this study was between 50 to 100 g NO₃-N m^-3 d^-1 to obtain a removal efficiency of 80-100%. It was found that approximately 6 mg SO₄^2- was produced for 1 mg NO₃-N removed. Nitrite-nitrogen in all cases was less than the maximum allowable concentration of 1 mg NO₂-N L^-1. Effluent pH was stable in the range of 7 to 8; the effluent dissolved oxygen was less than 0.15 mg L^-1 and the oxidation-reduction potential in all columns was in the range of -110 to -250 mV.

Keywords: Autotrophic Bacteria, Column Studies, Denitrification, Drinking Water, Groundwater, Limestone, Nitrate Removal, Sulfur, Thiobacillus Denitrificans, Autotrophic Denitrification Processes, Thiobacillus-Denitrificans, Elemental Sulfur, Drinking-Water, Systems, Batch

Vazquez, M.D., Wappelhorst, O. and Markert, B. (2004), Determination of 28 elements in aquatic moss Fontinalis antipyretica Hedw. and water from the upper reaches of the River Nysa (Cz, D), by ICP-MS, ICP-OES and AAS. Water Air and Soil Pollution, 152 (1-4), 153-172.

Full Text: W\Wat Air Soi Pol152, 153.pdf

Abstract: The concentrations of 28 elements in samples of the bryophyte F. antipyretica Hedw collected from various sites on the upper reaches of the River Nysa and its main tributaries were determined. These results were compared with similar analyses of water samples collected at the same sites. So, it was possible to determine the elemental composition of the water both directly and indirectly, using a bioindicator organism. Analyses were carried out using different instrumental techniques (ICP-MS, ICP-OES, AAS), some elements being analysed by both ICP-MS and ICP-OES. Functional regression analysis showed that for some of these elements, namely Al, Ba, Fe, Sr and Ti in moss, and Ba, Ca and Zn in water samples, there was no significant difference (p<0.05) in the concentrations determined by both techniques. The coefficients of correlation moss/water for each element were calculated, but they were in general low. However the coefficients of correlation between different elements were in general good. Finally, the elemental concentrations in the aquatic moss were also used to assess the level of contamination in the area of study, through the calculation of CF (Contamination Factor) values.

Keywords: AAS, Aquatic Moss, Bioaccumulation, Contamination Factor, Fontinalis Antipyretica, ICP, Multielement Analysis, River Nysa, Heavy-Metals, Multielement Analysis, Seasonal-Variations, Accumulation, Bryophytes, Germany, Samples

Martinson, L. and Alveteg, M. (2004), The importance of including the pH dependence of sulfate adsorption in a dynamic soil chemistry model. Water Air and Soil Pollution, 154 (1-4), 349-356.

Full Text: W\Wat Air Soi Pol154, 349.pdf

Abstract: Sulfate adsorption is an important process when modeling the dynamics of recovery from acidification. In the dynamic soil chemistry model SAFE sulfate adsorption is modeled by a pH and sulfate concentration dependent isotherm. This isotherm has been parameterized by fitting it to data from batch experiments on soil samples using multiple linear regression. The soil samples were from the B-horizon from three sites, two from the Lake Gardsjon area in south-west Sweden and one from southern Poland. The pH dependency of sulfate adsorption is important. The batch experiments show that the adsorbed amount, at a specific sulfate concentration, increases considerably with decreasing pH. This implies that the adsorbed pool of anthropogenic sulfate in soils may remain fairly high during the recovery phase. Although a decrease of sulfate concentration is commonly seen, the modeled pH increase is often slow, and thus delays in the modeled desorption of anthropogenic sulfate can be expected.

Keywords: Acidfication, Dynamic Modeling, Recovery, SAFE, Acid Deposition, Forest, Catchments

Zhao, X.K., Yang, G.P. and Wang, Y.J. (2004), Adsorption of dimethyl phthalate on marine sediments. Water Air and Soil Pollution, 157 (1-4), 179-192.

Full Text: W\Wat Air Soi Pol157, 179.pdf

Abstract: Experiments were performed to investigate the sorption behaviors of dimethyl phthalate on marine sediments. The sorption of dimethyl phthalate on marine sediments reached equilibrium within 10 h. The sorption behavior of dimethyl phthalate on HCl-treated and untreated sediments accorded well with the linear sorption isotherm. The sorption occurred primarily via partition function of organic carbon of marine sediments. The sorption behavior of dimethyl phthalate on H₂O₂-treated sediment was nonlinear and conformed to Freundlich isotherm. Sorption of dimethyl phthalate on H₂O₂-treated sediment was chiefly through surface function of clay in marine sediments. Salinity of seawater had an important effect on the sorption of dimethyl phthalate. As the salinity of seawater increased, both the partitioning coefficients K_d and empirical constant K would increase.

Keywords: Dimethyl Phthalate, Marine Sediment, Sorption, Partition, Linear Isotherm, Freundlich Isotherm

Ho, Y.S. and McKay, G. (2004), Sorption of copper(II) from aqueous solution by peat. Water Air and Soil Pollution, 158 (1), 77-97.

Full Text: W\Wat Air Soi Pol158, 77.pdf

Abstract: The use of peat for removal of copper(II) from aqueous solution has been investigated at various initial copper ion concentrations and masses of peat. The equilibrium sorption study can be described by the Langmuir equation and defined in terms of the operating lines for each batch contacting system. The mechanisms of the rate of sorption of copper(II) were analysed using the Elovich equation and a pseudo-second-order model. Both rate mechanisms provided a very high degree of correlation of the experimental sorption rate data suggesting either model could be used in design applications.

Keywords: Copper, Kinetics, Peat, Sorption

? Dey, S., Goswami, S. and Ghosh, U.C. (2004), Hydrous ferric oxide (HFO) - A scavenger for fluoride from contaminated water. Water Air and Soil Pollution, 158 (1), 311-323.

Full Text: 2004\Wat Air Soi Pol158, 311.pdf

Abstract: Groundwaters contaminated with excess fluoride (above 1.5 mg, L) posed some risks to the public health in India. Methods available for fluoride contaminated water treatment are cogaulation filtration using alum+lime+bleaching powder (Nalgonda technique) and adsorption using activated alumina. Use of aluminium compounds for water treatment purpose needs replacement on neurological health problem. Objective to this, the synthesis and fluoride adsorption behavior of hydrous ferric oxide (HFO) are reported here. It is seen that fluoride adsorption density varies as a function of pH, contact time, aging time, drying temperature and particle size of HFO. Highest adsorption density for fluoride is found to be at pH 4.0. Effects of competing anions in removing fluoride from solution were tested. Arsenite, arsenate, phosphate and sulfate show strong interfering effect at high anions to fluoride molar ratio in solution. Adsorption of fluoride on HFO follows the Freundlich isotherm and the Lagergren first-order kinetic model. It was also determined that HFO is a better adsorbent in removing fluoride from high fluoride groundwater than some other adsorbents. Regeneration of fluoride-rich HFO results showed that 1.0 M NaOH solution could be used up to a maximum of 75% regeneration.

Keywords: Adsorbent, Fluoride, Groundwater, Hydrous Ferric Oxide, Ions, Isotherm, Regeneration

? El-Shafey, E.I. (2005), Behaviour of reduction-sorption of chromium(VI) from an aqueous solution on a modified sorbent from rice husk. Water Air and Soil Pollution, 163 (1-4), 81-102.

Full Text: W\Wat Air Soi Pol163, 81.pdf

Abstract: A carbonaceous sorbent produced from rice husk via sulphuric acid treatment was used to remove Cr(VI) from aqueous solutions varying contact time, pH, Cr(VI) concentration and sorbent status (wet and dry). Cr(VI) was removed from the aqueous solution via reduction to Cr(III) and sorption. Reduction and sorption processes were investigated in terms of kinetics and equilibrium. The rate of reduction removal of Cr(VI) at pH 2 followed a pseudo first-order model while the rate of sorption of total chromium followed pseudo second-order model. Chromium sorption was highly dependent on the initial pH value with reduction taking place in solution with pH up to 7 showing sorption maxima in the pH range 1.8-2.8 for concentration range 100-500 mg/l with an increase in the equilibrium pH. Carbon dioxide evolved from the sorption media was determined. Reduction-sorption mechanism was investigated via physicochemical tests including cation exchange capacity, base neutralization and sorbent acidity in addition to FTIR studies for sorbent samples before and after sorption reaction.

Keywords: Carbon, Chromium(VI), Reduction, Rice Husk, Sorption, Surface Functional-Groups, Activated Carbon, Hexavalent Chromium, Removal, Adsorption, Peat, Adsorbent, Kinetics, Water

? Ahmad, R. (2005), Sawdust: Cost effective scavenger for the removal of chromium(III) ions from aqueous solutions. Water Air and Soil Pollution, 163 (1-4), 169-183.

Full Text: 2005\Wat Air Soi Pol163, 169.pdf

Abstract: Cr(III) ions sorption onto sawdust of spruce (Picea smithiana) has been studied thoroughly using radiotracer technique. Maximum sorption (94%) of Cr(III) ions (8.98×10⁻⁵ M) onto sorbent surface is achieved from deionized water in 20 min agitation time using 200 mg of sawdust. The sorption data followed the Freundlich, Dubinin-Radushkevich (D-R) and Langmuir isotherms. Freundlich constants l/n = 0.86 ± 0.07 and C_e = 85.0 ± 25.8 mmole g⁻¹ have been estimated. Sorption capacity, X_m = 0.82± 0.3 mmole g⁻¹, β = −0.00356± 0.00017 kJ² mole⁻² and energy, E = 11.9± 0.3 kJ mole⁻¹ have been evaluated using D-R isotherm. The Langmuir constants Q = 5.8± 0.2 μmole g⁻¹ and b = (7.4± 0.5)×10⁴ dm³ mole⁻¹ have been calculated. The variation of sorption with temperature yields thermodynamic parameters Δ H = −11.6± 0.3 kJ mole⁻¹, Δ S = −16.2± 0.9 J mole⁻¹ K⁻¹ and Δ G = −6.8± 0.3 kJ mole⁻¹ at 298 K. The negative value of enthalpy and free energy reflect the exothermic and spontaneous nature of sorption respectively. Among the anions studied oxalate, citrate, carbonate and borate have reduced the sorption. The cations Y(III), Ce(II) and Ca(II) suppressed sorption. The sawdust column can be used to separate Cr(III) ion from Cs(I), I(I), Tc(VII) and Se(IV).

Keywords: Cr(III) Ions, Kinetics, Radiotracer Technique, Sawdust, Sorption, Sorption Isotherms, Thermodynamics

? Kannan, N. and Rengasamy, G. (2005), Comparison of cadmium ion adsorption on various activated carbons. Water Air and Soil Pollution, 163 (1-4), 185-201.

Full Text: W\Wat Air Soi Pol163, 185.pdf

Abstract: Studies on the removal of cadmium(II) ions from aqueous solutions by adsorption on various activated carbons [commercial activated carbon (CAC) and chemically prepared activated carbons (CPACs) from raw materials such as straw, saw dust and datesnut] have been carried out with an aim to obtain information on treating effluents containing Cd(II) ions. Factors influencing the adsorption of Cd(II) ions from aqueous solution by ACs have been investigated by following a batch adsorption technique at 30±1C. The percentage removal increased with decrease in initial concentration and particle size of CPACs and an increase in contact time, dose and initial pH of the solution. Adsorption process was inhibited by the added electrolytes. The adsorption data were fitted with the Langmuir, Dubinim-Radushkevich and Freundlich isotherms and first-order kinetic equations viz., first-order, Lagergren and Bhattacharya-Venkobachar equations and intra-particle diffusion model. The kinetics of adsorption is first order with intra-particle diffusion as one of the rate determining steps. Thermodynamic parameters were obtained from equilibrium constants measured at 30, 35 and 40°C (Error = ± 1°C). Results of the studies on adsorption of Cd²⁺ ions from simulated wastewater were compared with that of CAC and Tulsion CXO-9(H), a commercial ion exchange resin/cationic resin (CR). Straw carbon showed the maximum adsorption capacity towards Cd²⁺ ions and a high value of rate constant of adsorption. Straw carbon is an alternative low-cost adsorbent to CAC.

Keywords: Adsorption, Cadmium(II) Ions, Chemically Prepared Activated Carbons (Cpacs), Comparison, Intra-Particle Diffusion, Isotherms, Kinetic Equations, Aqueous-Solution, Zinc, Lead, Equilibrium, Sorption, Removal, Copper, Cd, Pb

? Kim, J.H., Shin, W.S., Song, D.I. and Choi, S.J. (2005), Multi-step competitive sorption and desorption of chlorophenols in surfactant modified montmorillonite. Water Air and Soil Pollution, 166 (1-4), 367-380.

Full Text: 2005\Wat Air Soi Pol166, 367.pdf

Abstract: Single- and bi-solute sorption and desorption of 2,4-dichlorophenol (2,4-DCP) and 2,4,5-trichlorophenol (2,4,5-TCP) in montmorillonite modified with hexadecyltrimethylammonium (HDTMA) were investigated using multi-step sorption and desorption procedure. Effect of pH on the multi-step sorption and desorption was investigated. As expected by the magnitude of octanol-water partition coefficient, K_ow, both sorption and desorption affinity of 2,4,5-TCP was higher than that of 2,4-DCP at pH 4.85 and 9.15. For both chlorophenols, the protonated speciation (at pH 4.85) exhibited a higher affinity in both sorption and desorption than the predominant deprotonated speciation (about 95% and 99% of 2,4-dichlorophenolate and 2,4,5-trichlophenolate anions at pH 9.15, respectively). Desorption of chlorinated phenols was strongly dependent on the current pH regardless of their speciation in the previous sorption stage. Freundlich model was used to analyze the single-solute sorption and desorption data. No appreciable desorption-resistant (or non-desorbing) fraction was observed in organoclays after several multi-step desorptions. This indicates that sorption of phenols in organoclay mainly occurs via partitioning into the core of the pseudo-organic medium, thereby causing desorption nearly reversible. In bisolute competitive systems, sorption (or desorption) affinity of both chlorophenols was reduced compared to that in its single-solute system due to the competition between the solutes. The ideal adsorbed solution theory (IAST) coupled to the single-solute Freundlich model successfully predicted bisolute multi-step competitive sorption and desorption equilibria.

Keywords: Chlorophenols, Competition, Desorption, Hexadecyltrimethylammonium, Ideal Adsorbed Solution Theory, Montmorillonite, Organoclay, Sorption

? Jensen, P.E., Ottosen, L.M. and Pedersen, A.J. (2006), Speciation of Pb in industrially polluted soils. Water Air and Soil Pollution, 170 (1-4), 359-382.

Full Text: 2006\Wat Air Soi Pol170, 359.pdf

Abstract: This study was aimed at elucidating the importance of original Pb-speciation versus soil-characteristics to mobility and distribution of Pb in industrially polluted soils. Ten industrially polluted Danish surface soils were characterized and Pb speciation was evaluated through SEM-EDX studies, examination of pH-dependent desorption, distribution in grain-size fractions and sequential extraction. Our results show that the first factors determining the speciation of Pb in soil are: (1) the stability of the original speciation and (2) the contamination level, while soil characteristics are of secondary importance. In nine of ten soils Pb was concentrated strongly in the soil fines (< 0.063 mm). In all soils, particles with a highly concentrated Pb-content were observed during SEM-EDX. In eight of the soils, the particles contained various Pb-species with aluminum/iron, phosphate, sulfate and various metals (in solder and other alloys) as important associates. In the one soil, where Pb was not concentrated in the soil fines, Pb was precipitated solely as PbCrO₄, while pure (metallic) Pb was repeatedly observed in the last soil. Pb was bound strongly to the soils with > 50% extracted in step III (oxidizing) and IV (residual) of sequential extraction for all soils but one. A significant amount of exchangeable Pb existed only in severely contaminated soils, where the bonding capacity of organic matter and oxides was exceeded. Among soil constituents, Pb was observed to adsorb preferentially to feldspars and organic matter while presence of phosphate increased the strength of the Pb-bonding in phosphate-rich soils.

Keywords: Alloys, Capacity, Cd, Central Sweden, Competitive Adsorption, Contaminated Soils, Contamination, Cu, Desorption, Distribution, Examination, Extraction, Fines, Fractions, Grain Size, Heavy-Metals, Importance, IV, Lead Speciation, Matter, Metals, Mobility, Organic, Organic Matter, Organic-Matter, Oxides, Oxidizing, Particles, Pb, Phosphate, Pollution, SEM-EDX, Sequential Extraction, Shooting-Range Soils, Soil, Soils, Sorption, Speciation, Stability, Strength, Sulfate, Surface, Surface Soils, XRD

? Zeroual, Y., Kim, B.S., Kim, C.S., Blaghen, M. and Lee, K.M. (2006), Biosorption of bromophenol blue from aqueous solutions by Rhizopus stolonifer biomass. Water Air and Soil Pollution, 177 (1-4), 135-146.

Full Text: 2006\Wat Air Soi Pol177, 135.pdf

Abstract: The removal of bromophenol blue dye (BPB), from aqueous solutions, by biosorption on a non-living biomass of Rhizopus stolonifer was investigated in a batch system. Pretreatment of the biomass with NaOH was found to be the most effective means to enhance the biosorption of BPB. The fungal biomass exhibited the highest dye sorption capacity at pH 2 and the uptake process followed the pseudo-second order reaction model. The equilibrium sorption capacity of the biomass increased as the initial dye concentration increased, and the maximum uptake value was estimated at 1111 mg/g according to Langmuir adsorption isotherm. The adsorbed dye was easily desorbed from a fungal biomass with 0.1 M NaOH solution and the regenerated biomass could be reused for other biosorption essays with similar performances.

Keywords: Biosorption, Bromophenol Blue, Rhizopus Stolonifer, Reactive Dyes, Textile Effluent, Color Removal, Fungal Biosorption, Acid Dyes, Decolorization, Adsorption, Wastewaters, Kinetics, Sorption

? Liu, L., Tindall, J.A., Friedel, M.J. and Zhang, W.X. (2007), Biodegradation of organic chemicals in soil/water microcosms system: Model development. Water Air and Soil Pollution, 178 (1-4), 131-143.

Full Text: 2007\Wat Air Soi Pol178, 131.pdf

Abstract: The chemical interactions of hydrophobic organic contaminants with soils and sediments may result in strong binding and slow subsequent release rates that significantly affect remediation rates and endpoints. In order to illustrate the recalcitrance of chemical to degradation on sites, a sorption mechanism of intraparticle sequestration was postulated to operate on chemical remediation sites. Pseudo-first order sequestration kinetics is used in the study with the hypothesis that sequestration is an irreversibly surface-mediated process. A mathematical model based on mass balance equations was developed to describe the fate of chemical degradation in soil/water microcosm systems. In the model, diffusion was represented by Fick’s second law, local sorption-desorption by a linear isotherm, irreversible sequestration by a pseudo-first order kinetics and biodegradation by Monod kinetics. Solutions were obtained to provide estimates of chemical concentrations. The mathematical model was applied to a benzene biodegradation batch test and simulated model responses correlated well compared to measurements of biodegradation of benzene in the batch soil/water microcosm system. A sensitivity analysis was performed to assess the effects of several parameters on model behavior. Overall chemical removal rate decreased and sequestration increased quickly with an increase in the sorption partition coefficient. When soil particle radius, a, was greater than 1 mm, an increase in radius produced a significant decrease in overall chemical removal rate as well as an increase in sequestration. However, when soil particle radius was less than 0.1 mm, an increase in radius resulted in small changes in the removal rate and sequestration. As pseudo-first order sequestration rate increased, both chemical removal rate and sequestration increased slightly. Model simulation results showed that desorption resistance played an important role in the bioavailability of organic chemicals in porous media. Complete biostabilization of chemicals on remediation sites can be achieved when the concentration of the reversibly sorbed chemical reduces to zero (i.e., undetectable), with a certain amount of irreversibly sequestrated chemical left inside the soil particle solid phase.

Keywords: Biodegradation, Organic Chemicals, Sequestration, Soil/Water Microcosms System, Mathematical Model, Nonequilibrium Sorption, Intraparticle Diffusion, Aquifer Material, Soil, Kinetics, Rates, Degradation, Desorption, Transport, Sediments

? Chevalier, L.R. and Yesuf, J.N. (2007), Spreadsheet optimization for parameter estimation of pressure-saturation equations used for two-phase groundwater flow. Water Air and Soil Pollution, 179 (1-4), 57-65.

Full Text: 2007\Wat Air Soi Pol179, 57.pdf

Abstract: Spreadsheet optimization using a range of nonlinear error functions was utilized for parameter estimation of the two-phase pressure-saturation models developed by van Genuchten, Brutsaert, Russo and Kosugi. The data was obtained from the UNSODA database (US Salinity Laboratory, Riverside, California). Results show that spreadsheet optimization is a practical platform for evaluations based on minimizing nonlinear error functions, consequently allowing for a broader mathematical approach to parameter estimation. An error function representing the sum of the squares of errors provided the best fit for a majority of the soils evaluated, although the fractional error function provided the best fit for silts and loams. Outcomes indicated that the van Genuchten parameters m and n may also be estimated individually as opposed to following the published relationship of m=1-1/n.

Keywords: Pressure-Saturation Relationship, Optimization, Parameter Estimation, Two Phase Flow, Groundwater Flow, Lognormal-Distribution Model, Soil Hydraulic-Properties, Conductivity, Isotherm, Sorption

? Cortés-Martínez, R., Solache-Ríos, M., Martínez-Miranda, V. and Ruth Alfaro-Cuevas V. (2007), Sorption behavior of 4-chlorophenol from aqueous solutions by a surfactant-modified mexican zeolitic rock in batch and fixed bed systems. Water Air and Soil Pollution,