Personal Research Database

Full Text: 2006\Wat Res40, 943.pdf

Abstract: The impacts of distribution water quality changes caused by blending different source waters on lead release from corrosion loops containing small lead coupons were investigated in a pilot distribution study. The 1-year pilot study demonstrated that lead release to drinking water increased as chlorides increased and sulfates decreased. Silica and calcium inhibited lead release to a lesser degree than sulfates. An additional 3-month field study isolated and verified the effects of chlorides and sulfates on lead release. Lead release decreased with increasing pH and increasing alkalinity during the 1-year pilot study; however, the effects of pH and alkalinity on lead release, were not clearly elucidated due to confounding effects. A statistical model was developed using nonlinear regression, which showed that lead release increased with increasing chlorides, alkalinity and temperature, and decreased with increasing pH and sulfates. The model indicated that primary treatment processes such as enhanced coagulation and RO (reverse osmosis membrane) were related to lead release by water quality Chlorides are high in RO-finished water and increase lead release, while sulfates are high following enhanced coagulation and decrease lead release. (c) 2006 Elsevier Ltd. All rights reserved.

Keywords: Lead Corrosion, Water Blending, Water Quality, Statistical Regression, Pipe Distribution Systems, Solubility, Carbonate

? Zhang, Y. and Banks, C. (2006), Adsorption of Cu(II) to schwertmannite and goethite in presence of dissolved organic matter. Water Research, 40 (5), 969-974.

Full Text: 2006\Wat Res40, 969.pdf

Abstract: Sorption processes involving secondary iron minerals may significantly contribute to immobilisation of metals in soils and surface waters. In the present work the effect of dissolved organic matter (DOM) from a concentrated bog-water on the adsorption of Cu(II) onto schwertmannite (Fe₈O₈(OH)₆SO₄) and goethite (α-FeOOH) has been studied. The acid/base behaviour of DOM up to pH 6 was explained by assuming a diprotic acid with a density of carboxylate groups of 6.90 μeq (mg C)⁻¹. The resulting acidity constants, recalculated to zero ionic strength were and .

The uptake of DOM to schwertmannite and goethite was highest at low pH although adsorption was significant also under mildly alkaline conditions. Adsorption to the two minerals was similar although at high pH more DOM was adsorbed to schwertmannite than to goethite.

DOM enhanced the adsorption of Cu(II) at moderately low pH in the goethite system but there was no effect of DOM in the case of schwertmannite. The presence of Cu(II) resulted in a decreased adsorption of DOM to goethite at weakly acidic pH and increased adsorption at high pH. In the case of schwertmannite, Cu(II) did not affect DOM uptake.

Keywords: Adsorption, Schwertmannite, Goethite, Dissolved Organic Matter, Metal Attenuation, Acid Mine Drainage

? Saleh, M.M. (2006), On the removal of cationic surfactants from dilute streams by granular charcoal. Water Research, 40 (5), 1052-1060.

Full Text: 2006\Wat Res40, 1052.pdf

Abstract: Adsorption of a cationic surfactant; cetylpyridinium chloride (CPyCl) on granular charcoal (GC) was used to remove the surfactant from dilute solutions. The removal process was performed using both batch and continuous processes. In the batch process, the effects of different operating parameters on the removal efficiency were studied. The GC was found to be efficient and removal efficiencies up to 98% were obtained at certain conditions. The removal efficiency was found to increase with the amount of charcoal, shaking speed and temperature. It increased with the surfactant concentration and reaches quickly to maximum constant ranges but it decreases at higher concentrations near the cmc of the surfactant. The resistance for further decreases in the removal efficiency was dependent of the operating conditions. Adsorption of CPyCl on the GC was found to follow the kinetics of a first-order reaction. Activation energy of adsorption and SEM images suggested that diffusion inside the porous matrix could be a controlling step. Modified Frumkin isotherm was applied to the collected data at different temperatures. The results of removal of CPyCl using packed bed of GC at flowing conditions were also discussed. Higher values of the conversion efficiency, Ψ were obtained at low flow rates and thicker beds. The results were discussed on the light of a dimensionless conversion factor, Φ=υr2/2DLθ, which includes important structural and hydrodynamic parameters. The experimental data showed a satisfactory agreement with the theoretical trends.

Keywords: Cetylpyridinium, Charcoal, Granular, Removal, Porous

? Lemić, J., Kovačević, D., Tomašević-Čanović, M., Kovačević, D., Stanić, T. and Pfend, R. (2006), Removal of atrazine, lindane and diazinone from water by organo-zeolites. Water Research, 40 (5), 1079-1085.

Full Text: 2006\Wat Res40, 1079.pdf

Abstract: Systematic adsorption tests were carried out to determine the efficiency of organo-zeolite (OZ) for removal of atrazine, lindane and diazinone from water. The hydrophobic character of OZ-pesticide interactions was confirmed by measuring the amount of pesticides sorbed on zeolite samples modified with 25, 50, 75 and 150 mmol of stearyldimethylbenzylammoniumchloride (SDBAC)/kg of zeolite. The effects of adsorbent particle size, solid content in the suspension and the initial pesticide concentration in the solutions were also investigated. For effective adsorption of diazinone onto an OZ, it is necessary for the SDBAC/diazinon ratio to be higher than 25. The adsorption capacities, calculated by fitting the experimental data to the Langmuir–Freundlich equation, were 2.0 μmol/g (atrazine), 4.4 μmol/g (diazinone) and 3.4 μmol/g (lindan). At lower initial concentrations of pesticide solution, a linear dependence existed between the amount adsorbed and the equilibrium concentration of pesticide. Column experiments showed that at volumetric flow of 6 cm³/min, the breakthrough points (at C/C₀ = 0.1) were 560 bed volume (BV) for lindane and 620 for diazinone.

Keywords: Pesticide, Adsorption, Organo-Zeolite

? Li, Y.J., Li, X.D., Li, J.W. and Yin, J. (2006), Photocatalytic degradation of methyl orange by TiO₂-coated activated carbon and kinetic study. Water Research, 40 (6), 1119-1126.

Full Text: 2006\Wat Res40, 1119.pdf

Abstract: TiO₂-coated activated carbon (AC) grain (TiO₂/AC) was prepared through hydrolytic precipitation of TiO₂ from Tetrabutylorthotitanate and following heat treatment. The TiO₂/AC was characterized by BET, SEM, XRD and optical absorption spectroscopy. The samples were employed as catalysts for methyl orange photocatalytic oxidation degradation in aqueous suspension, used as probe reaction. The kinetics of methyl orange photo degradation was analyzed. The results indicate that BET surface area of TiO₂-coated ACs decreased drastically in comparison with the original AC with increasing TiO₂ coatings by more than 1 doped cycle. Nano-TiO₂ particles were dispersed on the AC with the size of 20-40 nm, Crystalline TiO₂ doped onto AC was from anatase to rutile with increase of heat-treatment temperature. The TiO₂/AC was shown high photoactivity for the photodegradation of methyl orange (MO) dyestuff in aqueous solution under UV irradiation. The kinetics of photocatalytic MO dyestuff degradation was found to follow a pseudo-first-order rate law. It was observed that the presence of the AC enhanced the photoefficiency of the titanium dioxide catalyst. Different amount of TiO₂ coatings induced different increases in the apparent first-order rate constant of the process. The kinetic behavior could be described in terms of a modified Langmuir-Hinshelwood model. The values of the adsorption equilibrium constants for the organic molecules, K-C, and for the rate constants, k(c), were certainly dependent on TiO₂ content. At 47 wt% TiO₂ coatings with the highest rate constant, the K-C and k(c) was 0.11161 mmol(-1) and 0.1872 mmol(-1) min(-1), respectively. The mechanism of methyl orange degradation was discussed in terms of the titanium dioxide photosensitization by the AC. (c) 2006 Published by Elsevier Ltd.

Keywords: Activated Carbon, Adsorption, Anatase-Type TiO₂, Behavior, Equilibrium, Heterogeneous Photocatalysis, Induced, Kinetics, Mechanism, Methyl Orange Degradation, Model, Modified, Oxidation, Photocatalyst, Precipitation, Pseudo-First-Order, Quantum Yields, Rate Constant, Relative Photonic Efficiencies, Technical Report, Terminology, Titania, Titanium Dioxide, Treatment, Water, XRD

? Pekakis, P.A., Xekoukoulotakis, N.P. and Mantzavinos, D. (2006), Treatment of textile dyehouse wastewater by TiO₂ photocatalysis. Water Research, 40 (6), 1276-1286.

Full Text: 2006\Wat Res40, 1276.pdf

Abstract: The oxidative degradation of an actual textile dyehouse wastewater was investigated by means of photocatalysis in the presence of TiO₂. The UV-A-induced photocatalytic oxidation over TiO₂ suspensions was capable of decolorizing the effluent completely, as well as reducing chemical oxygen demand (COD) sufficiently (COD reduction generally varied between about 40% and 90% depending on the operating conditions) after 4 h of treatment. Two crystalline forms of TiO₂, viz. anatase and rutile, were tested for their photocatalytic activity and anatase was found to be more active than rutile. The extent of photocatalytic degradation was found to increase with increasing TiO₂ concentration up to 0.5 g/L TiO₂, above which degradation remained practically constant, reaching a plateau. Furthermore, textile effluent degradation was enhanced at acidic conditions (i.e. pH = 3) and in the presence of hydrogen peroxide. To assess catalyst activity on repeated use, experiments were performed where the catalyst was recovered and reused; after three successive uses, TiO₂ had sufficiently retained its photocatalytic activity. Finally, the luminescent marine bacteria Vibrio fischeri was used to assess the acute ecotoxicity of samples prior to and after the photocatalytic treatment and it was found that ecotoxicity was fully eliminated following photocatalytic oxidation.

Keywords: Textile wastewater, Photocatalysis, TiO₂, Catalyst reuse, Ecotoxicity

? Fatin-Rouge, N., Dupont, A., Vidonne, A., Dejeu, J., Fievet, P. and Foissy, A. (2006), Removal of some divalent cations from water by membrane-filtration assisted with alginate. Water Research, 40 (6), 1303-1309.

Full Text: 2006\Wat Res40, 1303.pdf

Abstract: The removal of divalent metal ions from hard waters or galvanic wastewater by polymer-assisted membrane filtration using alginate was investigated. The ability of this natural polymer to form aggregates and gels in presence of metal ions was studied, in order to carry out metal removal by ultra or micro-filtration. Alginate titrations have shown the presence of amine groups in addition to carboxylates onto the polymer backbone. The binding properties of alginate with divalent cations have been studied, showing an increasing affinity for Ca²⁺ over Mg²⁺ as polymer concentration increases, and the relative affinity Pb²⁺  Cu²⁺ > Zn²⁺ > Ni²⁺. The softening of hard natural waters was achieved successfully and easily, but needs an optimal alginate concentration 4×10⁻² M. The alginate powder can be directly added to hard waters. Except for Ni²⁺, metal-removal was efficient. Polymer regeneration has shown that Cu²⁺-complexes are labiles.

Keywords: Ultrafiltration Complexation, Polymer-Assisted Filtration, Wastewater Treatment, Water Softening, Metal Removal, Alginate

? Oporto, C., Arce, O., Van den Broeck, E., Van der Bruggen, B. and Vandecasteele, C. (2006), Experimental study and modelling of Cr (VI) removal from wastewater using Lemna minor. Water Research, 40 (7), 1458-1464.

Full Text: 2006\Wat Res40, 1458.pdf

Abstract: The removal of Cr(VI) from wastewater by Lemna minor was studied both at laboratory and pilot scale. Laboratory tests were conducted under different conditions of initial Cr(VI) concentration (0.5 and 2.0 mg/l) and temperature (285 and 291 K). Batch experiments were carried out during 16 days in which the chromium concentrations, both in the biomass and in wastewater were measured. Data were used to characterize the biouptake capacity of the biomass; results showed that it increases with the temperature and when the initial Cr concentration decreases. The biouptake process could be fitted by an equation, with a correlation coefficient of 0.98. The removal process was assessed using the data of the variation of chromium concentration in the wastewater with respect to time; this allowed obtaining constant parameters which were applied in a mathematical model for the assessment of duckweed systems in a pilot scale plant.

Keywords: Lemna minor, Cr(VI), Biouptake, Removal, Wastewater, Mathematical Model, Pilot Scale Plant, Duckweed

? Drizo, A., Forget, C., Chapuis, R.P. and Comeau, Y. (2006), Phosphorus removal by electric arc furnace steel slag and serpentinite. Water Research, 40 (8), 1547-1554.

Full Text: 2006\Wat Res40, 1547.pdf

Abstract: Electric arc furnace (EAF) steel slag and serpentinite were tested in columns either alone or mixed with limestone to determine their capacity to remove phosphorus (P) from a solution containing initially 20 mg P/L (for 114 days) than 400 mg P/L (for 21 days). EAF steel slag was nearly 100% efficient due to specific P adsorption onto metal hydroxides and precipitation of hydroxyapatite. Serpentinite also showed a good performance that decreased with time, adsorption appearing to be the dominant mechanism for P removal. Mixing limestone with these two materials did not improve their performance and in the case of serpentinite, it actually even decreased it. In 114 days of experimentation, serpentinite alone and the mixture of serpentinite and limestone removed 1.0 mg P/g while in 180 days of experimentation, EAF steel slag and the mixture of slag and limestone removed an average of 2.2 mg P/g, without attaining their maximum P removal potential. The void hydraulic retention time (HRTv) was a key factor for growing hydroxyapatite crystals and had a significant effect on P removal efficiency by EAF steel slag. A temporary increase in HRTv caused by clogging resulted in an increase in EAF steel slag efficiency (from 80% to almost 100%) towards the end of investigation. Results from this study indicate that the use of EAF steel slag in constructed wetlands or filter beds is a promising solution for P removal via adsorption and precipitation mechanisms. (c) 2006 Elsevier Ltd. All rights reserved.

Keywords: Adsorption, Adsorption, Calcium, Constructed Wetland Systems, Hydroxyapatite, Magnesium, Mechanism, Phosphate Removal, Phosphorus, Phosphorus Removal, Phosphorus Retention, Precipitation, Precipitation, Retention, Saturation, Slag, Soils, Sorption, Steel Slag, Waste-Water, Wetlands

? Ruotolo, L.A.M., Santos-Junior, D.S. and Gubulin, J.C. (2006), Electrochemical treatment of effluents containing Cr(VI). Influence of pH and current on the kinetic. Water Research, 40 (8), 1555-1560.

Full Text: 2006\Wat Res40, 1555.pdf

Abstract: Compounds of Cr(VI) are very toxic and their reduction to Cr(III) is necessary to allow their further precipitation or adsorption. Chemical methods for Cr(VI) reduction are usually used for this purpose. As an alternative, electrochemical methods using three-dimensional electrodes, such as reticulated vitreous carbon (RVC) and polyaniline-modified RVC, have been used successfully Since the pH affects reaction of Cr(VI) reduction, in this work its effect on the reaction rate was studied using electrodes of RVC and RVC/PANI. While a maximum in reaction rate was found for a pH 1.5 using the RVC, the RVC/PANI showed no differences in reaction rates in the range of pH between 0 and 1. Practically, no reaction was observed for any pH greater than 3. The effect of different current densities using optimized pH was also evaluated and the RVC/PANI electrode showed the best reaction rates, current efficiencies and energy consumption as a result of the polyaniline electrocatalytic effect. (c) 2006 Elsevier Ltd. All rights reserved.

Keywords: Adsorption, Aqueous-Solutions, Carbon Electrodes, Chromium(VI), Conducting Polymer-Films, Cr(VI), Current Efficiency, Energy, Hexavalent Chromium, pH, Polyaniline, Polyaniline, Polypyrrole, Precipitation, Reaction Rates, Reactor, Reduction, Reticulated Vitreous Carbon, Stability, Treatment

? Joss, A., Zabczynski, S., Gobel, A., Hoffmann, B., Loffler, D., McArdell, C.S., Ternes, T.A., Thomsen, A. and Siegrist, H. (2006), Biological degradation of pharmaceuticals in municipal wastewater treatment: Proposing a classification scheme. Water Research, 40 (8), 1686-1696.

Full Text: 2006\Wat Res40, 1686.pdf

Abstract: A simple classification scheme is suggested to characterize the biological degradation of micropollutants such as pharmaceuticals, musk fragrances and estrogens during wastewater treatment. The scheme should be a basis for the discussion about potential removal efficiencies. Hence, the biological degradation of 25 pharmaceuticals, hormones and fragrances was studied in batch experiments at typical concentration levels using activated sewage sludge originating from nutrient-eliminating municipal wastewater treatment plants.

Since pseudo first-order degradation kinetics was observed for all compounds down to ngL(-1) levels, the removal rates can be predicted for various reactor configurations. Therefore dilution of wastewater (e.g. by extraneous water) is expected to reduce the degree of biological removal. Wastewater segregation and treatment at the source are therefore to be favoured for elimination of persistent micropollutants over centralized end-of-pipe treatment. For reactor configurations typical for nutrient removal in municipal wastewater, the derived formula for predicting removal allows the identification of three groups of micropollutants according to their degradation constant k(biol): compounds with k(biol)<0.1Lg(ss)(-1)d(-1) are not removed to a significant extent (<20%), compounds with k(biol)>10Lg(ss)(-1)d(-1) transformed by >90% and in-between moderate removal is expected. Based on the degradation of a heterogeneous group of 35 compounds (including literature data), state of the art biological treatment schemes for municipal wastewater are not efficient in degrading pharmaceuticals: only 4 out of 35 compounds are degraded by more than 90% while 17 compounds are removed by less than 50%.

Keywords: Municipal Wastewater, Micropollutants, Pharmaceuticals, Hormones, Activated Sludge, Membrane Bioreactor, Tandem Mass-Spectrometry, Sewage-Treatment Plants, Surface Waters, Drinking-Water, Aquatic Environment, Musk Fragrances, Estrogenic Chemicals, Contrast-Media, STW Effluent, Sludge

? Vieira, R.S. and Beppu, M.M. (2006), Dynamic and static adsorption and desorption of Hg(II) ions on chitosan membranes and spheres. Water Research, 40 (8), 1726-1734.

Full Text: 2006\Wat Res40, 1726.pdf

Abstract: The adsorption and desorption of Hg(II) ions was studied using static and dynamic methods, employing membranes and spheres of chitosan as the adsorbent. The quantity of adsorption was influenced by chitosan crosslinking and by the adsorbent shape. The Langmuir model was applied to fit the experimental equilibrium data. Glutaraldehyde-crosslinked membranes presented a lower desorption capacity, when compared to natural membranes, but could be regenerated for use in successive cycles. Dynamic adsorption experiments suggested that the adsorption capacity depended mainly on adsorbent geometry, due to differences between surface area to mass ratio and initial concentration of Hg(II) ions. The adsorption capacity determined by the dynamic method was 65% and 77% for membranes and spheres, respectively of the value obtained static method results. A process combining dynamic adsorption and static desorption can be used to concentrate the Hg(II) ions by a factor of nearly seven (7×), when compared to the initially treated volume.

Keywords: Chitosan, Heavy Metal, Mercury, Adsorption

? Ngomsik, A.F., Bee, A., Siaugue, J.M., Cabuil, V. and Cote, G. (2006), Nickel adsorption by magnetic alginate microcapsules containing an extractant. Water Research, 40 (9), 1848-1856.

Full Text: 2006\Wat Res40, 1848.pdf

Abstract: The adsorption of heavy metals on biomaterials was investigated by studying the potential of alginate microcapsules containing an extractant (Cyanex 272) and magnetic nanoparticles (γ-Fe₂O₃) for the adsorption of nickel(II) from aqueous solutions. A two-stage kinetics behaviour was observed with 70% of the maximum sorption capacity achieved within 8 h. An increase in nickel removal with increase in pH occurred, the maximum uptake capacity being around 0.42 mmol g^–1 at pH 8. The adsorption isotherm (pH about 5.3) was obtained in a wide range of initial nickel concentrations; the experimental data were fitted by a Langmuir model and the q_max value was estimated to be 0.52 mmol g^–1. Moreover, including magnetic particles in the microcapsules allowed easy isolation of the beads from the aqueous solutions after the sorption process. Magnetic microcapsules are then suitable for the development of efficient biosorbents for removal and recovery of heavy metals from wastewater using magnetic separation.

Keywords: Magnetic Nanoparticles, Alginate, Cyanex 272, Microcapsule, Metal Removal

? Li, A.M. and Dai, J.Y. (2006), Effects of fulvic fractions on the pH-dependent sorption of Cu(II) to kaolinite. Water Research, 40 (10), 1951-1956.

Full Text: 2006\Wat Res40, 1951.pdf

Abstract: Sorption of copper on kaolinite in the absence and presence of four fulvic acid (FA) fractions fractionated using XAD-8 resin, including F4.8, F7.0, F11.0 and Feth fractions (eluted by pH4.8 buffer, pH7.0 buffer, pH11.0 buffer, and ethanol (95%), respectively, was investigated by batch experiments. Results showed that the binding of Cu(II) by pure kaolinite increased with an increase in pH values. The presence of each FA fraction significantly affects the sorption of Cu(II) to kaolinite. Below pH 6.3, Cu(II) sorption was pronouncedly promoted after adding FA fraction to binary systems, compared to that in pure kaolinite suspensions. Magnitude in enhancement of Cu(II) sorption to solid phase, which was caused by FA fractions, followed an order of F4.8>F7.0>11.0>Feth. Above pH 6.3, nearly all the Cu(II) were removed from solution in pure koalinte system, while a portion of Cu(II) left in aqueous phase via formation of dissolved Cu–FA complexes, was observed in systems in the presence of FA fractions. The largest Cu(II) distribution coefficients (K_d) between solid phase and aqueous solution at pH 3.15–5.7, are obtained from the ternary system with F4.8 fraction. The smallest K_d are from system in the presence of Feth fraction. Conversely, over a pH range from 5.7 to 7.0, the highest K_d values are from system with Feth fraction.

Overall, F4.8 fraction exhibited the greatest effect on Cu(II) pH-dependent sorption to kaolinite, and Feth fraction had the least. Functional groups such as carboxyl, phenolic moieties of FA played the vital role in Cu(II) sorption to kaolinite at lower pH conditions, and solubility under neutral conditions.

Keywords: Kaolinite, FA Fractions, Copper, Adsorption

? Nowack, B. and Stone, A.T. (2006), Competitive adsorption of phosphate and phosphonates onto goethite. Water Research,