Personal Research Database

Full Text: W\Wat Res35, 745.pdf

Abstract: Delayed petroleum coke, a waste by-product from the oil sand industry, was utilized in the production of activated carbon. The activated carbon was then evaluated for color and chlorinated organics reduction from pulp mill wastewater. The activation of the petroleum coke was evaluated using a fixed bed reactor involving carbonization and activation steps at temperature of 850 degreesC and using steam as the activation medium. The activation results showed that the maximum surface area of the activated coke was achieved at an activation period of 4h. The maximum surface area occurred at burnoff and water efficiency of 48.5 and 54.3%, respectively. Increasing the activation period to 6 h resulted in a decrease in the surface area. Methylene blue adsorption results indicated that the activation process was successful. Methylene blue adsorbed per 100 g of applied activated coke was 10 times higher than that adsorbed by raw petroleum coke. Adsorption equilibrium results of the bleached wastewater and the activated coke showed that significant color, COD, DOC and AOX removal (> 90%) was achieved when the activated coke dose exceeded 15.000 mg/L. Adsorption isotherms, in terms of GOD. DOG, UV and color were developed based on the batch equilibrium data. Based on these isotherms, the amount of activated coke required to achieve certain removal of color and AOX can be predicted. The utilization of the petroleum coke for the production of activated carbon can provide an excellent disposal option for the oil sand industry at the same time would provide a cheap and valuable activated carbon. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: AOX, Adsorption, Color, Isotherm, Pulp Mills, Petroleum Coke, Effluent

Schmitt, D., Muller, A., Csogor, Z., Frimmel, F.H. and Posten, C. (2001), The adsorption kinetics of metal ions onto different microalgae and siliceous earth. Water Research, 35 (3), 779-785.

Full Text: W\Wat Res35, 779.pdf

Abstract: In the present work the adsorption kinetics of the six metal ions aluminum, zinc, mercury, lead, copper. and cadmium onto living microalgae were measured. The freshwater green microalga Scenedesmus subspicatus. the brackish water diatom Cyclotella cryptica the seawater diatom Phaeodactylum tricornutum, and the seawater red alga Porphyridium purpureum were the subject of investigation. In most cases the adsorption rate of the metals could be well described by using the equation of the Langmuir adsorption rate expression. Inverse parameter estimation allowed the determination of the rate constants of the adsorption process and the maximum metal content of the algae. The highest values for the rate constant were obtained for Porphyridium purpureum followed by Phaeodactylum tricormutum. High values for the maximum content were obtained for Cyclotella cryptica and Scenedesmus subspicatus. The maximum rate constant was 24.21 h^-1 for the adsorption of Hg to Porphyridium purpureum whereas the maximum metal content (0.243 g g^-1) was obtained for Zn on Cyclotella cryptica. A comparison of these values with those obtained for the mineral siliceous earth exhibiting low maximum content and high adsorption rates reveals that the mechanism of adsorption onto the algae is a mixture of adsorption and accumulation. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Microalgae, Adsorption, Kinetics, Metals, Biosorption, Bioaccumulation, Biosorption, Cadmium, Biomass

Olivie-Lauquet, G., Gruau, G., Dia, A., Riou, C., Jaffrezic, A. and Henin, O. (2001), Release of trace elements in wetlands: Role of seasonal variability. Water Research, 35 (4), 943-952.

Full Text: W\Wat Res35, 943.pdf

Abstract: Dissolved concentrations were determined for Fe, Mn, Al, Cu, Zn, La, U, Th, Cd and As in a wetland and its recipient stream to reveal the effect of seasonal changes in environmental conditions on the cycling and transfer of trace elements at the transition between terrestrial and aquatic ecosystems. These preliminary results from the wetland show marked seasonal changes in dissolved concentration for all elements except Zn and Cu. Concentrations are found to be low until about mid-February and then increase abruptly. The onset of trace element release appears to coincide with a marked decline in redox potential and increase of organic carbon content. Because this decline is itself correlated with a pronounced increase in temperature and dissolved Fe, Mn and organic carbon content, we suggest that the microorganisms which use soil iron and manganese oxy-hydroxides as electron accepters catalyzed the change in redox conditions and induced an increase of DOC. Temporal changes were also observed in the recipient stream which showed marked positive concentration peaks during stormflow events (except Zn). The seasonal processes occurring in the wetland appear to play a major role in determining the amount of trace elements which are transferred from the wetland to the river. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Trace Elements, Dissolved Organic Carbon, Wetlands, Redox Conditions, Organic-Matter Decomposition, Hydromorphic Soils, Drainage-Basin, Water-Quality, Iron, Metals, Sediment, Carbon

Ricou-Hoeffer, P., Lecuyer, I. and Le Cloirec, P. (2001), Experimental design methodology applied to adsorption of metallic ions onto fly ash. Water Research, 35 (4), 965-976.

Full Text: W\Wat Res35, 965.pdf

Abstract: The objective of this study was to define operating conditions which would conciliate a high removal of the five metallic cations (Cu²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Pb²⁺) and a low desorption of these metal ions from the contaminated sorbents. To achieve this goal the strategy relied on the use of experimental design methodology. The influence of four parameters (fly ash/lime mass ratio, type of fly ash/lime sorbent solution temperature, and sorbent concentration) on the removal at pH = 5 and the stabilization of the five metallic ions was studied. In the first step, the influence of three parameters on the removal of Cu²⁺ ions was studied (R₂ = fly ash/lime mass ratio, type of sorbent, temperature). It was found that the same set of parameter values would produce both the highest removal and the lowest desorption for this cation: R₂ = 9g g^-1, sorbent B (made by mixing fly ash and lime in water, then drying this paste at 105 degreesC for 24 h), temperature of suspension equal to 60 degreesC. The formation of calcium silicate hydrate (CSH), resulting from the pozzolanic activity of fly ash, is assumed to be partially responsible for these mechanisms. In the second step, simplex methodology and Doehlert matrix were used to find the conditions in a 2D space (sorbent concentration, temperature of solution) that would give the highest removal from a solution containing five metallic cations and the lowest desorption of these five cations adsorbed on the contaminated sorbents. Then, the system response that had to be optimized was the total metallic ions concentration (TMIC, mol L^-1). A TMIC was measured both for adsorption and leaching experiments. These responses were modelized using a second-order polynomial and the surface responses were plotted for adsorption and desorption results. A difference was observed between operating conditions reaching the highest adsorption from those that gave the lowest desorption. However, an adsorbent concentration around 122 g L^-1 and a solution temperature of 66 degreesC would lead simultaneously to a high adsorption and a low desorption. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Fly Ash/Lime Mixing, Metallic Ions, Adsorption, Experimental Design, Optimal Conditions, Leaching, Aqueous-Solution, Removal, Sorption, Cations, Water

? Chamarro, E., Marco, A. and Esplugas, S. (2001), Use of fenton reagent to improve organic chemical biodegradability. Water Research, 35 (4), 1047-1051.

Full Text: 2001\Wat Res35, 1047.pdf

Abstract: Fenton reagent has been used to test the degradation of different organic compounds (formic acid, phenol, 4-chlorophenol, 2,4-dichlorophenol and nitrobenzene) in aqueous solution. A stoichiometric coefficient for the Fenton reaction was found to be 0.5 mol of organic compound/mol of hydrogen peroxide, except for the formic acid where a value of approximately one was obtained (due to the direct formation of carbon dioxide). The treatment eliminates the toxic substances and increases the biodegradability of the treated water (measured as the ratio BOD5/COD). Biodegradability is attained when the initial compound is removed.

Keywords: Fenton Reagent, Advanced Oxidation Technologies (AOT)

Notes: highly cited

Gupta, V.K., Gupta, M. and Sharma, S. (2001), Process development for the removal of lead and chromium from aqueous solutions using red mud: An aluminium industry waste. Water Research, 35 (5), 1125-1134.

Full Text: W\Wat Res35, 1125.pdf

Abstract: Red mud, an aluminium industry waste, has been converted into an inexpensive and efficient adsorbent and used for the removal of lead and chromium from aqueous solutions. Effect of various factors on the removal of these metal ions from water (e.g. pH, adsorbent dose, adsorbate concentration, temperature, particle size, etc.) has been studied and discussed. The effect of presence of other metal ions/ surfactants on the removal of Pb²⁺ and Cr⁶⁺ has also been studied. The material exhibits good adsorption capacity and the data follow both Freundlich and Langmuir models. Thermodynamic parameters indicate the feasibility of the process. Kinetic studies have been performed to understand the mechanism of adsorption. Dynamic modelling of lead and chromium removal on red mud has been undertaken and found to follow first-order kinetics. The rate constant and mass transfer coefficient have also been evaluated under optimum conditions of removal in order to understand the mechanism. Column studies have been carried out to compare these with batch capacities. The recovery of Pb²⁺ and Cr⁶⁺ and chemical regenertion of the spent column have also been tried. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Lead, Chromium Removal, Adsorption, Red Mud, Low-Cost Adsorbent, Bagasse Fly-Ash, Activated Carbon, Fertilizer Waste, Water Treatment, Sugar-Industry, Metal-Ions, Adsorption, Sorption, Cadmium

Dönmez, G. and Aksu, Z. (2001), Bioaccumulation of copper(II) and nickel(II) by the non-adapted and adapted growing Candida sp. Water Research, 35 (6), 1425-1434.

Full Text: W\Wat Res35, 1425.pdf

Abstract: The effect of copper(II) and nickel(II) ions on the growth and bioaccumulation properties of non-adapted and adapted growing cells of a non-pathogenic Candida sp. has been tested under laboratory conditions as a function of initial pH and initial metal ion concentration. Optimum pH value for maximum metal ion accumulation was determined as 4.0 for both the metal ions. Although the copper(II) adapted Candida sp. was capable of removing of copper(II) with the maximum specific uptake capacity of 36.9 mg g^-1 at 783.6 mg dm^-3 initial copper(II) concentration, non-adapted Candida was only capable of bioaccumulating copper(II) with 23.1 mg g^-1 maximum uptake capacity from aqueous solution at 578.7 mg dm^-3 initial copper(II) concentration. The non-adapted and nickel(II) adapted Candida cells also showed the highest nickel(II) uptake capacities (46.8 and 30.8 mg g^-1, respectively) at 321.5 and 300.6 mg dm^-3 initial nickel(II) concentrations, respectively. For both the non-adapted and nickel(II) adapted Candida sp., the growth of cells was totally inhibited by 500 mg dm^-3 of nickel(II) ions. The results also indicated that copper(II) adapted Candida sp. has been found to be more efficient to accumulate larger amounts of copper(II) than that of nickel(II) bioaccumulated by nickel(II) adapted Candida at higher initial metal ion concentrations without loosing its biological activity. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Bioaccumulation, Copper(II), Nickel(II), Adapted, Non-Adapted, Candida sp., Saccharomyces-Cerevisiae, Metal-Ions, Biosorption, Removal, Cu(II), Cr(VI), Yeasts, Water, Cells

Gregor, J. (2001), Arsenic removal during conventional aluminium-based drinking-water treatment. Water Research, 35 (7), 1659-1664.

Full Text: W\Wat Res35, 1659.pdf

Abstract: The changing forms and concentrations of arsenic through aluminium-based coagulation treatment processes were tracked for three drinking-water treatment plants. This has provided direct evidence of where and how arsenic is removed. In general, soluble As(V) is converted to particulate As(V) by adsorption during rapid mixing, and is removed along with naturally occurring particulate arsenic predominantly by clarification. Soluble As(III) tracks through the treatment processes and is converted to soluble As(V) during final chlorination. The ability of a water treatment process to achieve the maximum acceptable concentration for arsenic in drinking water is dependent on the concentration of As(III) in the source water. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Arsenic, Forms, Removal, Aluminium, Coagulation, Coagulation, River

Lu, X.Q. and Jaffe, R. (2001), Interaction between Hg(II) and natural dissolved organic matter: A fluorescence spectroscopy based study. Water Research, 35 (7), 1793-1803.

Full Text: W\Wat Res35, 1793.pdf

Abstract: Interaction between Hg(II) and dissolved organic matter (DOM) collected from surface water samples of the Florida Everglades was studied using different fluorescence spectroscopic methods. Complexation between Hg(II) and DOM leached from mangrove leaves, sawgrass, and periphyton was investigated. Both fluorescence emission and synchronous fluorescence spectra showed that these dissolved organic materials, whether they are highly degraded or are freshly leached, can ‘complex’ Hg(II) since fluorescence intensity was quenched upon addition of Hg(II) to the DOM samples. Synchronous fluorescence spectra disclosed structural information on the DOM sample, regarding possible binding sites for Hg(II). Chemical parameters on the complexation of Hg(II), including the conditional stability constants and the percentage of fluorophores participating in the complexation, were estimated by the modified Stern-Volmer equation. A detailed investigation under different experimental conditions showed that the complexation of the DOM samples collected from the Everglades was influenced by pH, Cl^-(aq)(-) anion, and cations such as Ca²⁺ and Mg²⁺. Experimental results suggest that DOM-Hg(II) complexes run be removed from the water column through adsorption on biogenically precipitated CaCO_3(s). (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Dissolved Organic Matter, Hg(II), Fluorescence, Complexation, Stability Constants, Fulvic-Acid, Complexing Capacities, Florida Everglades, Humic Substances, Surface Waters, Metal-Ions, Mercury, Copper, Complexation, Mobilization

Coro, E. and Laha, S. (2001), Color removal in groundwater through the enhanced softening process. Water Research, 35 (7), 1851-1854.

Full Text: W\Wat Res35, 1851.pdf

Abstract: The source of water for Miami-Dade County, Florida is groundwater derived from the Biscayne aquifer. The raw water is rich in natural organic material producing correspondingly high color levels. Currently, breakpoint chlorination is used at the water treatment plant to control the color problem. However, this results in the formation of disinfection by-products. Proposed alternatives to reduce color and avoid by-product formation include the addition of coagulants such as ferric chloride and organic polymers, and the operation of the existing lime softening process at a higher pH. This study uses jar tests to evaluate the relative effectiveness of the proposed alternatives. Results indicate that significant color reduction is achieved using the existing lime softening process with activated silica coagulant by increasing the softening pH to 11 or more. Elevated pH also produced a > 30% reduction in total organic carbon. In the presence of higher raw water color (greater than or equal to 80 units), the addition of ferric chloride as coagulant at dosages of 80 mg/L is recommended. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Natural Organic Matter, Lime Softening, Breakpoint Chlorination, Disinfection By-Products

Notes: highly cited

? Tiehm, A., Nickel, K., Zellhorn, M. and Neis, U. (2001), Ultrasonic waste activated sludge disintegration for improving anaerobic stabilization. Water Research, 35 (8), 2003-2009.

Full Text: 2001\Wat Res35, 2003.pdf

Abstract: The pretreatment of waste activated sludge by ultrasonic disintegration was studied in order to improve the anaerobic sludge stabilization. The ultrasound frequency was varied within a range from 41 to 3217 kHz. The impact of different ultrasound intensities and treatment times was examined. Sludge disintegration was most significant at low frequencies. Low-frequency ultrasound creates large cavitation bubbles which upon collapse initiate powerful jet streams exerting strong sheer forces in the liquid. The decreasing sludge disintegration efficiency observed at higher frequencies was attributed to smaller cavitation bubbles which do not allow the initiation of such strong shear forces. Short sonication times resulted in sludge floc deagglomeration without the destruction of bacteria cells. Longer sonication brought about the breakup of cell walls, the sludge solids were disintegrated and dissolved organic compounds were released. The anaerobic digestion of waste activated sludge following ultrasonic pretreatment causing microbial cell lysis was significantly improved, There was an increase in the volatile solids degradation as well as an increase in the biogas production. The increase in digestion efficiency was proportional to the degree of sludge disintegration. To a lesser degree the deagglomeration of sludge flocs also augmented the anaerobic volatile solids degradation. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Anaerobic Digestion, Sludge Stabilization, Biogas, Ultrasound, Cavitation, Disintegration, Digestion

Notes: highly cited

Lin, T.F. and Wu, J.K. (2001), Adsorption of arsenite and arsenate within activated alumina grains: Equilibrium and kinetics. Water Research, 35 (8), 2049-2057.

Full Text: W\Wat Res35, 2049.pdf

Abstract: Equilibrium and kinetic adsorption of tri-valent (arsenite) and penta-valent (arsenate) arsenic to activated alumina is elucidated. The properties of activated alumina. including porosity. specific surface area, and skeleton density were first measured. A batch reactor with temperature control was employed to determine both adsorption capacity and adsorption kinetics For arsenite and arsenate to activated-alumina grains. The Freundlich and Langmuir isotherm equations were then used to describe the partitioning behavior for the system at different pH. A pore diffusion model, coupled with the observed Freundlich or Langmuir isotherm equations, was used to interpret an observed experimental adsorption kinetic curve for arsenite at one specific condition. The model was found to fit with the experimental data Fairly well, and pore diffusion coefficients can be extracted. The model. incorporated with the interpreted pore diffusion coefficient, was then employed to predict the experimental data Tor arsenite and arsenate at various conditions, including different initial arsenic concentrations, grain sizes of activated alumina, and system pHs. The model predictions were found to describe the experimental data fairly well, even though the tested conditions substantially differed From one another. The agreement among the models and experimental data indicated that the adsorption and diffusion of arsenate and arsenite can be simulated by the proposed model. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Activated Alumina, Adsorption, Arsenate, Arsenic, Arsenite, Diffusion, Diffusion, Ferrihydrite, Transport, Sorption, Pellets

Inglezakis, V.J., Hadjiandreou, K.J., Loizidou, M.D. and Grigoropoulou, H.P. (2001), Pretreatment of natural clinoptilolite in a laboratory-scale ion exchange packed bed. Water Research, 35 (9), 2161-2166.

Full Text: W\Wat Res35, 2161.pdf

Abstract: The impact of the operational and chemical conditions of pretreatment upon the effective capacity of clinoptilolite has been investigated. Pretreatment tests have been performed in an ion exchange packed bed. The parameters examined for the pretreatment solution were the volumetric flow rate, the concentration, the total volume and the pH; and for washing after pretreatment the volume of washing water used. An optimal flow rate and a minimum concentration were determined, for a pretreatment that leads to a high effective capacity of the material, while pH adjustment did not result in a higher effective capacity and one washing (10 bed volumes) after pretreatment was found to be sufficient. Furthermore, the water quality (use of tap water) as well as the surface dust of the original material (about 5% w, w) did not alter its effective capacity. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Ammonia Removal, Capacity, Clinoptilolite, Ion Exchange, Lead, Metals, Packed Bed, Pretreatment, Zeolites

Bayhan, Y.K., Keskinler, B., Cakici, A., Levent, M. and Akay, G. (2001), Removal of bivalent heavy metal mixtures from water by Saccharomyces cerevisiae using crossflow microfiltration. Water Research, 35 (9), 2191-2200.

Full Text: W\Wat Res35, 2191.pdf

Abstract: The removal of heavy metal ions, Ni²⁺, Cu²⁺ and Pb²⁺ using yeast (Saccharomyces cerevisiae) as carriers in a crossflow microfiltration is investigated The affects of yeast cell and electrolyte concentrations on the transient and steady-state permeate flux and metal ion rejections are established. It is found that the metal ion rejection reaches a plateau if yeast cell concentration is greater than similar to 2 g/l as a result of cell aggregation. The binding affinity of the metals to yeast cell is Pb²⁺ > Cu²⁺ > Ni²⁺, which is also reflected in the metal ion rejection under identical process conditions. Because of the formation of yeast cell flocks in the presence of Pb²⁺, permeate flux is also higher for this metal. The presence of NaCl decreases both rejection and permeate flux for Ni²⁺ and Cu²⁺ but not for Pb²⁺. When binary or ternary metal mixtures are used, the rejection of the individual metals is reduced except that of Pb²⁺. It is found that the pseudo-gel concentration is unaffected by the presence of metal ions. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Heavy Metals, Sacharomyces Cerevisiae, Crossflow Microfiltration, Wastewater Treatment, Flow Filtration, Surfactant Dispersion, Aqueous-Solutions, Permeate Flux, Erythrocytes, Separation, Rejection, Polymers

Dantas, T.N.D., Neto, A.A.D. and Moura, M.C.P.D. (2001), Removal of chromium from aqueous solutions by diatomite treated with microemulsion. Water Research, 35 (9), 2219-2224.

Full Text: W\Wat Res35, 2219.pdf

Abstract: In order to evaluate the sorption of heavy metals, a crude diatomite was impregnated with a microemulsion which showed remarkable increase in chromium sorption capacity as compared to untreated diatomite. Samples with two different granulometries were investigated, both yielding practically complete adsorption. The adsorption process is pH dependent and the best results for the initial Cr(III) concentration of 1.5g/L were obtained at pH 2.95. The effect of the concentration of the chromium synthetic solution was also investigated. The adsorption isotherms were obtained (30, 40 and 50°C) and the Freundlich and Langmuir models were used to determine the adsorption capacity of the adsorbent. Following the adsorption step, a desorption process was carried out using several eluant solutions. The best results were obtained using hydrochloric acid (100%) as eluant. (C) 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Heavy Metals, Diatomite, Microemulsion, Chromium, Adsorption, Desorption, Heavy-Metals, Adsorption, Wastes, Lead

Seida, Y., Nakano, Y. and Nakamura, Y. (2001), Rapid removal of dilute lead from water by pyroaurite-like compound. Water Research,