Personal Research Database

Full Text: W\Wat Res33, 2826.pdf

Abstract: An extended Langmuir model was proposed in this work to describe the simultaneous absorption of multiple divalent metal ions and hydrogen ions from acidic metal-containing aqueous media by an absorbent having one kind of active functional group. A viscous Na-alginate solution was directly dispensed dropwise into the acidic aqueous media containing dissolved copper and zinc to form spherical Cu-Zn-H-alginate gels which subsequently absorb these ions until final equilibrium was reached in batch experiments. Initial pH of the aqueous media was in the range of 2.6-5.4. Binding group density and binding stability constants of alginic acid, cupric alginate and zinc alginate were obtained simultaneously by fitting data to the proposed model developed in this work. Application of the constants obtained to the prediction of the extent of absorption of copper and zinc from an aqueous medium having an initial pH in the range of 2.6-5.4 is illustrated and compared with experimental results. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Copper, Zinc, Alginate, Selectivity, Metal Recovery, Langmuir Model, Copper

Bao, M.L., Griffini, O., Santianni, D., Barbieri, K., Burrini. D. and Pantani, F. (1999), Removal of bromate ion from water using granular activated carbon. Water Research, 33 (13), 2959-2970.

Full Text: W\Wat Res33, 2959.pdf

Abstract: This study investigated the feasibility of using granular activated carbon (GAC) to remove bromate ion (BrO₃-) from drinking water through a rapid small-scale column test (RSSCT) method and a pilot-scale study. Results from RSSCT tests indicated that the GAC capacity for BrO₃- removal was carbon-specific and dependent on the source water quality and empty bed contact time (EBCT). The presence of dissolved organic carbon (DOC) and anions, Such as bromide, nitrate, and sulfate, resulted in poor BrO₃- reduction. On the other hand, BrO₃- removal was improved by increasing EBCT. The reduction capacity of spent GAC could be completely recovered by thermal regeneration. Under RSSCT conditions, the results showed that preloading with natural water significantly decreased the capacity of GAC for BrO₃- removal whereas in the pilot plant study, a GAC column (operating with 20-min EBCT) preloaded for 110 days achieved a BrO₃- removal ranging from 57 to 92% for at least 98 days, and the BrO₃- amount removed was found to be proportional to the influent BrO₃- concentration. These limited data suggest that if suitable GAC is used, GAC performed in the biological mode may achieve a longer bedlife for BrO₃- removal. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Bromate Reduction, Activated Carbon Filtration, Ozonation, Biologically Activated Carbon, Drinking Water Treatment, Bromide-Containing Waters, Ozonation, Ozone

Snukiškis, J.J., Kaušpėdienė, D.V. and Gefenienė, A.J. (1999), Simultaneous removal of nonionic surfactant and heavy metal(II). Water Research, 33 (13), 2978-2982.

Full Text: W\Wat Res33, 2978.pdf

Abstract: Simultaneous sorption of nonionic surfactant (alkylmonoethers ALM-10) and heavy metal cations (lead, nickel) by Purolite C 106 carboxylic acrylcationic exchanger has been investigated. Sorption isotherms and kinetic curves were measured using spectrophotometric determination for nonionic surfactant and complexometric titration for heavy metals. The sorption of metal cations, surfactant molecules and products of their interaction takes place simultaneously. In the absence of surfactant the sorption of metal cations determined experimentally corresponds to that calculated from the change in the equilibrium solution pH, assuming that two hydrogen cations are replaced by one metal cation. In the presence of surfactant the change in pH is lower than that without surfactant: the total sorption of metal determined experimentally is higher than that calculated From the change in pH. It is because the sorption of metal takes place in the form of not only free cations but also cations bonded to the surfactant. The sorption of metal bonded to the surfactant can be evaluated from both the total metal adsorbed which was determined experimentally and the sorption of the free cations. The total sorption of lead(II) is higher than that of nickel(II) (transition metal). Subsequently the action of lead(II) results in the decrease of the equilibrium sorption of surfactant while the action of nickel(II) on the equilibrium sorption of surfactant is insignificant. The sorption of metal cations decreases in the presence of surfactant. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Lead(II), Nickel(II), Nonionic Surfactant, Cation Exchanger, Water Recycling, Copper, Nickel

Tran, H.H., Roddick, F.A. and O’Donnell, J.A. (1999), Comparison of chromatography and desiccant silica gels for the adsorption of metal ions. I. Adsorption and kinetics. Water Research, 33 (13), 2992-3000.

Full Text: W\Wat Res33, 2992.pdf

Abstract: In this study desiccant silica gel (DSG was compared with chromatography silica gel (CSG) for its ability to remove metal ions including Pb²⁺, Cu²⁺, Ni²⁺, Zn²⁺, Cd²⁺ and UO₂²⁺ from solution. The equilibration lime was shorter for UO₂²⁺ (less than 1 h) than for the heavy metal ions (2-3 h) and adsorption by DSG look longer to reach equilibrium compared with CSG, probably due to the smaller mean diameter of its pores. The adsorption process showed first order kinetics for all the metals studied. The mass transfer coefficients and overall rate constants were determined for each of the metals. The adsorption rates of the metal ions, in order of decreasing magnitude, were UO2²⁺ > Pb²⁺ >-Cu²⁺ > Zn²⁺ >Ni²⁺ > Cd²⁺ for both DSG and CSG. Metal uptake was found to increase rapidly within a two pH unit range characteristic for each metal. The adsorption of the metal ions obeyed the Langmuir isotherm and followed the preferential order UO₂²⁺ > Pb²⁺ > Cu²⁺ > Ni²⁺ >Zn²⁺ >Cd²⁺. Similarity of the isotherms for the individual metals was observed for both DSG and CSG, indicating a comparable removal capacity of DSG and its possible use as an alternative to CSG in adsorption applications. Adsorption from lead(II)-uranium(VI) solutions showed that the uptake of each metal was considerably reduced with an increasing concentration of the other, the adsorption of lead(II) being more strongly influenced by uranium(VI) than vice versa due to the higher affinity of silica gel for the latter.

Keywords: Uranyl Ions, Removal, Sorption, Silica Gel, Adsorption, Metal Ions, Uranium, Adsorption Kinetics

Tran, H.H. and Roddick, F.A. (1999), Comparison of chromatography and desiccant silica gels for the adsorption of metal ions. II. Fixed-bed study. Water Research, 33 (13), 3001-3011.

Full Text: W\Wat Res33, 3001.pdf

Abstract: The adsorption of uranium(VI) and lead(II) on fixed beds of chromatography silica gel (CSG) and desiccant silica gel (DSG) was investigated at initial pH 5.15 and an initial concentration of 0.5 and 0.1 mM for uranium(VI) and lead(II), respectively, and exhibited a constant pattern of breakthrough curves at various bed heights and flow rates. The experimental data gave a good fit to the bed depth-service time (BDST) model at 50% breakthrough with the bed capacity close to the value predicted from batch study results. The adsorption performance of the silica gel columns could be well described by the Clark model at the ratios of concentration of effluent to influent (C/C₀) up to 0.3 for uranium(VI) and 0.5 for lead(II). Above these levels, the model was approximately valid for uranium(VI), while a large deviation occurred with lead(II) adsorption. Application of the Wolborska model to the data at C/C₀ ratios lower than 0.5 enabled the determination of the kinetic coefficients for mass transfer in these systems. Furthermore, it was found that uranium(VI) could be effectively separated from lead(II) by using a column packed either with CSG or DSG at pH 3.50. Complete removal of uranium(VI) adsorbed to a packed bed of silica gel was obtained by employing 4.5 M HNO₃ as eluant. Six and seven bed volumes of 4.5 M HNO₃ were required for the elution of uranium(VI) from CSG and DSC, respectively. For lead(II), complete desorption From the column required 3.0 and 3.5 bed volumes of 1.5 M HNO₃ solution for CSG and DSG, respectively. For both uranium(VI) and lead(II) it was found that the DSG-packed column exhibited better performance than CSG in terms of service time and volume of solution treated, and gave similar value of the adsorbent usage rate, suggesting that DSG can be used instead of CSG in column applications.

Keywords: Activated-Carbon Systems, Removal, Silica Gel, Metal Ions, Uranium, Fixed Bed, Packed Bed

Caza, N., Bewtra, J.K., Biswas, N. and Taylor, K.E. (1999), Removal of phenolic compounds from synthetic wastewater using soybean peroxidase. Water Research, 33 (13), 3012-3018.

Full Text: W\Wat Res33, 3012.pdf

Abstract: Experiments were conducted to investigate the efficiency of using soybean peroxidase (SBP) to remove several different phenolic compounds from unbuffered synthetic wastewater. The phenol derivatives studied included parent phenol, chlorinated phenols, cresols, 2,4-dichlorophenol and 4,4’-isopropylidenediphenol (commonly known as bisphenol A). Optimum conditions to achieve at least 95% removal of these compounds were determined for the following parameters: pn, SEP dose in the absence and presence of polyethylene glycol (PEG), hydrogen peroxide to substrate ratio, and PEG dose, Experimental results showed that SEP efficiently removed aromatic compounds from synthetic wastewater in the presence of hydrogen peroxide. An increase in the hydrogen peroxide to substrate ratio beyond the optimum resulted in enzyme inactivation in all cases except for bisphenol A. The optimum pH for different phenolic compounds ranged from 5.5 to 8. For each substrate. the optimum enzyme dose in the presence of PEG varied significantly. The studies showed that PEG only slightly reduced the amount of SEP required For 95% removal of the substrate. For most of the substrates, an increase in PEG dose beyond the optimum dose did not significantly change the removal efficiency. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Soybean Peroxidase, Aromatic Compounds, Enzymatic Removal, Polyethylene Glycol, Horseradish-Peroxidase, Additives, Optimization, Water

Chu, W. (1999), Lead metal removal by recycled alum sludge. Water Research, 33 (13), 3019-3025.

Full Text: W\Wat Res33, 3019.pdf

Abstract: In this study, alum sludge was recycled using a chemical precipitation process to promote the removal of lead metal in wastewater. To make the process more cost-effective, two different pH ranges were suggested for daily operation, depending on the involvement or otherwise of an aluminum regeneration process at a later stage. If aluminum regeneration was expected, an elevated pH (11.6) was suggested to optimize both the aluminum regeneration and lead removal. Lead hydroxide coprecipitated with alum sludge in alkaline conditions, where the high pH would also facilitate the alkaline regeneration of alum at a later stage. With the use of recycled alum sludge (RAS) in the coagulation process, lead removal rates increased from 79% to 96-98% with 100-180 mg/l of RAS, while the required fresh alum dosage was reduced from 175 mg/l to 50-12.5 mg/l only, If no fresh alum is added to the system, the RAS can still remove up to 94% of lead at low recycling doses (75-100 mg/l), which suggests that the sweep-flee mechanism is crucial to the sludge reuse process. However, if the regeneration of aluminum is not required, a lower initial pH (10.5) should be used to decrease chemical costs. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Alum, Coagulation, Floc, Lead, Recycle, Sludge

Lu, X.Q., Chen, Z.L. and Yang, X.H. (1999), Spectroscopic study of aluminium speciation in removing humic substances by Al coagulation. Water Research, 33 (15), 3271-3280.

Full Text: W\Wat Res33, 3271.pdf

Abstract: Removal of humic substances (HS) isolated from swamp water. surface soil. peat and brown coal by aluminium (Ai) coagulation under different conditions was studied using the jar test method and spectroscopic techniques. At lower pHs < 4.5, humic substances formed soluble complexes with Al³⁺ and the amounts of these HS-Al complexes increased with increasing concentration of the humic substances. Maximum removal of the humic substances was found to occur in the pH range from 5.0 to. 7.0, due to the adsorption of humic substances on the surface of Al(OH)_3(s) crystal. Sequential extraction of the humic substances adsorbed on Al(OH)_3(s) using the Soxhlet technique with different solvents showed that the adsorption forces involved were great. The effects of humic substances on the Al speciation are discussed and a model is proposed-to explain the mechanism for the removal of humic substances during the Al coagulation process. (C) 1999 Elsevier Science Ltd. Ail rights reserved.

Keywords: Humic Substances, Al Coagulation, Jar Test, Complexation, Adsorption, 27A1 NMR Spectroscopy, Micro-Infrared Spectroscopy, X-Ray Diffraction, Aqueous-Solutions, Acids, Chlorination, Complexes, Waters, Color, Mx

Yang, J.B. and Volesky, B. (1999), Biosorption of uranium on Sargassum biomass. Water Research, 33 (15), 3357-3363.

Full Text: W\Wat Res33, 3357.pdf

Abstract: Protonated, non-living biomass of the brown alga Sargassum fluitans effectively sequestered uranyl ions from aqueous solution, with the maximum uranium sorption capacity exceeding 560 mg/g, 330 mg/g and 150 mg/g at pH 4.0, 3.2 and 2.6, respectively. At various pH levels, batch sorption equilibrium was reached within 3 h and the sorption isotherms were interpreted in terms of the Langmuir model. The sorption system pH profoundly affected uranium sorption capacities and sorption mechanisms through the hydrolysis of uranyl ions in aqueous solution. While only UO₂²⁺ ions existing at pH 2.6 were exchanging with protons on the biomass, the high uranium sorption at pH 4.0 was attributed to the existence of hydrolysed uranyl ions, UO₂OH⁺, (UO₂)₃(OH)₅⁺ and (UO₂)₂(OH)₂²⁺. Each mole of uranium binding to the biomass was accompanied by the consumption of approximately 2 mol of LiOH for maintenance of the desired constant pH. The uranium could be easily recovered from the metal-loaded biomass by elution with 0.1 N HCl. The desorption was complete and the damage to the biomass was slight. These findings indicate an enormous potential of biosorption in uranium removal from aqueous solutions. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.

Keywords: Biosorption, Biosorbent, Equilibrium, Uranium, Alga, Sargassum, Heavy-Metals, Marine-Algae, Bioaccumulation, Biotechnology

Swedlund, P.J. and Webster, J.G. (1999), Adsorption and polymerisation of silicic acid on ferrihydrite, and its effect on arsenic adsorption. Water Research, 33 (16), 3413-3422.

Full Text: W\Wat Res33, 3413.pdf

Abstract: The interaction between silicic acid (H₄SiO₄) and ferrihydrite involves both adsorption and polymerisation, and has a significant effect on the adsorption of anionic species such as the oxyanions of arsenic. Using the diffuse layer model (DLM), the adsorption constants for H₄SiO₄, As(V), and As(III) adsorption onto ferrihydrite have been determined from experimental adsorption data. Silicic acid could be considered to adsorb as a monomer when the total Si to Fe mole ratio (Si-(T)/Fe) was < 0.1, and the inhibitory effect of H₄SiO₄ on As(III) and As(V) adsorption could be accurately modelled using the DLM. At higher Si-(T)/Fe ratios, H₄SiO₄ polymerisation on the ferrihydrite surface appeared to become increasingly important. However, even when Si-(T)/Fe = 1.8 and there would have been significant H₄SiO₄ polymerisation, the DLM continued to predict almost all of the observed effect of H4SiO4 on As(III) and As(V) adsorption while taking only H₄SiO₄ adsorption into account. This suggests that H₄SiO₄ adsorption inhibits Pls adsorption to a greater degree than H₄SiO₄ polymerisation. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Silicic Acid, Arsenic, Adsorption, Ferrihydrite, Diffuse Layer Model, Surface-Chemistry, Iron-Oxides, Spectroscopy, Mechanism, Sediments, Stability

? Wong, Y.X. and Yu, J. (1999), Laccase-catalyzed decolorization of synthetic dyes. Water Research, 33 (16), 3512-3520.

Full Text: W\Wat Res33, 3512.pdf

Abstract: Commercial dyes are not uniformly susceptible to microbial attack in conventional aerobic treatment because of their unique and stable chemical structures. Three synthetic dyes with typical chromophores (anthraquinone, azo and indigo) were decolorized by a white-rot fungus Trametes versicolor. The responsible enzyme for dye decomposition was laccase, an extracellular oxidase released by the fungus under the conditions of slow growth or in its stationary phase. The mechanism of laccase-catalyzed dye decomposition, however, was different depending on dye structures. Anthraquinone dye was an enzyme substrate that was directly oxidized by laccase while decolorization of azo and indigo dyes involved some small molecule (<8 kDa) metabolites. It was demonstrated that azo and indigo dyes were not the substrates of laccase and the small molecule metabolites mediated the interaction between the dyes and the enzyme. The decolorization rate of the nonsubstrate dyes was actually limited by the concentration of mediating compounds rather than laccase activity in the solutions. Some synthetic compounds such as 2,2’-azino-bis(3-ethylthiazoline-6-sulfonate) or ABTS and anthraquinone dye could also mediate the decolorization of azo and indigo dyes. The mediating function of ABTS and anthraquinone dye was quantitatively compared in the decomposition of two nonsubstrate dyes. This fact implies that the laccase-substrate dyes in an industrial effluent can promote the decolorization of those nonsubstrate dyes. Effluent decolorization, therefore, may not be limited by the small molecule metabolites which are not produced in large amount by fungus in most industrial effluents. A laccase-catalyzed and mediator-involved dye degradation mechanism is proposed for further kinetic studies.

Keywords: Synthetic Dye, Decolorization, Laccase, Enzyme-Mediator Mechanism, White-Rot Fungus

van Noort, P.C.M. (1999), Comment on ‘The sorption of lead(II) ions on peat’ by Y. S. Ho and G. McKay, Water Research 33(2), 578-584 (1999). Water Research, 33 (16), 3541-3543.

Full Text: W\Wat Res33, 3541.pdf

Ho, Y.S. and McKay, G. (1999), Comment on ‘The sorption of lead(II) ions on peat’ by Y.S. Ho and G. McKay, Water Research 33 (2), 578-584 (1999)-Authors’ reply. Water Research, 33 (16), 3544.

Full Text: W\Wat Res33, 3544.pdf

Omoike, A.I. and Vanloon, G.W. (1999), Removal of phosphorus and organic matter removal by alum during wastewater treatment. Water Research, 33 (17), 3617-3627.

Full Text: W\Wat Res33, 3617.pdf

Abstract: Ferron reagent and FTIR spectroscopy were used for the identification and characterization of the aluminum species formed during dephosphorization of simulated wastewater with and without organic matter. Evidence from FTIR spectroscopy showed the formation of aluminum hydroxyphosphate, hydroxy-Al-tannate and aluminum complexes containing both phosphorus and tannic acid. The surface reactivity of the solid products is proportional to the rate of reaction with ferron. The measured reactivities indicate that aluminum solid species with different surface properties were formed depending on solution components and method of precipitation. Tannic acid was found to inhibit phosphorus removal and the extent of inhibition increased with increasing concentration. When prehydrolyzed aluminum is exposed to tannic acid, the organic matter forms a coating on the surface of the inorganic solid during the aging process. Coprecipitation of aluminum, phosphate and tannic acid, which is synonymous with the addition of alum before or in the aerator, produces some soluble complex and some hydroxy-Al-phosphate-tannate complex, in the form of solid with very small particle size. This system gives high residual aluminum. The results suggest that it is advantageous to add at least a portion of the alum at the exit of the aerator. This enhances phosphorus removal by coprecipitation under conditions where the concentration of organic matter is relatively low and enhances removal of organic matter by postprecipitation onto the recycled sludge in the aerator. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Coprecipitation, Postprecipitaion, Wastewater, Surface Reactivity, Tannic Acid, Residual Phosphorus, Residual Tannic Acid, Tannic-Acid, Precipitation Products, Coagulation, Montmorillonite, Adsorption, Hydroxy-A1, Hydroxide, Surface, Ligands, Ions

Ivancev-Tumbas, I., Dalmacija, B., Tamas, Z. and Karlovic, E. (1999), The effect of different drinking water treatment processes on the rate of chloroform formation in the reactions of natural organic matter with hypochlorite. Water Research, 33 (18), 3715-3722.

Full Text: W\Wat Res33, 3715.pdf

Abstract: This study is concerned with the changes in the rate of chloroform formation during the reactions of groundwater natural organic matter (NOM) and sodium hypochlorite caused by different drinking water treatments schemes: coagulation with FeCl₃, Al₂ (SO₄)₃ and polyaluminum chloride (PACl), filtration of the raw water through granular activated carbon (GAC) and filtration through the columns filled with strong base macroporous ion-exchange resins (Purolite A501P and A500P) with and without pretreatment by coagulation process. It was found that the change of the concentration of chloroform, within 2 h and c (Cl₂) = 100 mg l^-1, can be described by a kinetic equation of the form [CHCl₃] = a + bt (c). On the basis of this equation rates of the reaction were calculated. All processes applied decreased the rate of chloroform formation (process of coagulation moderately decreased the rate of reactions, while GAC adsorption caused dramatically drop of the rate). Also, it was found that the resins have had a higher affinity towards slow-reacting chloroform precursors. The value of the chloroform formation potential was conventionally determined after a 7-day reaction at pH 7. In addition, the same parameter was estimated with a satisfactory deviation for raw water and for treated water on the basis of the kinetic constant (k) or by determining the chloroform concentration after 2 h (ChFP (2)) under rigourous chlorination conditions at pH 8.4. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Trihalomethane Formation, By-Products, Model, Groundwater, Chloroform Formation, Natural Organic Mater, Trihalomethane Formation Potential, Hypochlorite

Figueira, M.M., Volesky, B., Ciminelli, V.S.T. and Roddick, F.A. (2000), Biosorption of metals in brown seaweed biomass. Water Research, 34 (1), 196-204.

Full Text: W\Wat Res34, 196.pdf

Abstract: Biosorption of Cd by biomass of the brown seaweeds Durvillaea, Laminaria Ecklonia and Homosira presaturated with Ca. Mg or K was coupled with the release of these light ions. The feasibility of biomass pre-treatment to develop a better biosorbent was evaluated by its biosorption performance, the degree of its component leaching (measured by the weight loss and TOC) as well as by the number of ion-exchange sites remaining in the biomass after the pre-treatment. Multicomponent Langmuir and ion exchange models applied to the equilibrium sorption data for pH 4.5 confirmed the ion exchange mechanism involved in the biosorption of metals. Both models fitted well the experimental data and their parameters can be used in the derivation of dimensionless ion-exchange isotherms which are instrumental in predicting the behavior of the biosorbents in dynamic flow-through biosorption systems. The sequence of biomass affinities established for the selected heavy metals can be correlated with the chemical pretreatment of the biomass. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Biosorption, Brown Seaweed, Heavy Metal, Ion Exchange, Heavy-Metal, Ion-Exchange, Marine-Algae, Binding, Biosorbent, Alginate, Polymers, Removal, Protons, Radiata

Carbonell-Barrachina, A.A., Jugsujinda, A., Burlo, F., Delaune, R.D. and Patrick, Jr., W.H. (2000), Arsenic chemistry in municipal sewage sludge as affected by redox potential and pH. Water Research,