Personal Research Database

Full Text: W\Wat Res36, 2898.pdf

Abstract: The purpose of the work is to study the adsorption of gallium(III) on bentonite from aqueous solutions. The important parameters, which affect the adsorption, such as pH of solution, mass of bentonite and temperature have been investigated. The results of parameters study showed that when pH and mass of bentonite increase there was a significant increase of Ga(III) at 20°C and the optimum conditions were as follows: pH of solution (2.50), mass of bentonite (3.50 g) and temperature (20°C). An experimental test carried out using a factorial design 2³ indicated that pH and mass of bentonite have a positive effect, whereas temperature has negative effect. The interaction effect between pH and mass of bentonite was an important significant factor for gallium adsorption.

Keywords: Gallium(III), Bentonite, Adsorption

Pala, A. and Tokat, E. (2002), Color removal from cotton textile industry wastewater in an activated sludge system with various additives. Water Research, 36 (11), 2920-2925.

Full Text: W\Wat Res36, 2920.pdf

Abstract: The low biodegradability of many dyes and textile chemicals indicates that biological treatment is not always successful in the treatment of cotton textile wastewater, in terms of color removal. In this study, a specific organic flocculant (Marwichem DEC), powdered activated carbon (PAC), bentonite, activated clay and commercial synthetic inorganic clay (Macrosorb) were directly added into the activated sludge laboratory pilot plant model. Before dosage, the optimum sludge retention time and hydraulic retention time were determined as 30days and 1.6days, respectively. The Monod kinetic constants were determined as Y=0.76 kg MLSS/kg COD, K_d=0.026 1/day, K_s=113.3 mg/L, k=0.42 1/day and μ_max=0.32 kg MLSS/kg CODday. Under these conditions the average COD removal was 94% and color removal was 36%. The addition of these materials did not change COD removal significantly. The most effective materials were found to be DEC and PAC for color removal. While the color removal efficiency for 120 mg/L DEC addition was 78%, it was 65% for 100 mg/L, 77% for 200 mg/L and 86% for 400 mg/L PAC addition.

The advantage of DEC compared to PAC was the lower sludge production. Statistical analyses using multiple linear regression indicate that there is no relationship between the effluent color with the influent color and total suspended solids (TSS) for DEC and PAC addition. On the other hand, when only bentonite, activated clay and Macrosorb were added, the effluent color was primarily dependent on the influent color and the TSS concentration had little effect. When the data is examined by using Kruskal–Wallis H and Mann–Whitney U tests and it was found that there was a significant difference between the color data groups.

Keywords: Activated Sludge, Textile Industry Wastewater, Color Removal, Adsorbents

Juang, R.S. and Shao, H.J. (2002), A simplified equilibrium model for sorption of heavy metal ions from aqueous solutions on chitosan. Water Research, 36 (12), 2999-3008.

Full Text: W\Wat Res36, 2999.pdf

Abstract: The amounts of sorption of Cu²⁺, Ni²⁺, and Zn²⁺ from water on cross-linked chitosan were measured. Experiments were performed as a function of initial pH (2–5), total metal concentration (0.77–17 mol/m³), and metal concentration ratio (0.25–4) at 25 °C in single- and binary-metal systems. The sorption was so highly pH dependent that the isotherm could not be described by one specific equation. A simplified equilibrium model was thus proposed considering competitive sorption of proton and metal ions. The number of active sites on chitosan bound with one metal ion was adjustable and model parameters could be graphically determined. Given initial metal concentrations and solution pH, the proposed model could predict the amounts of sorption of proton and metals as well as the equilibrium pH. In general, application of the model parameters calculated in single-metal systems to the prediction of sorption in binary-metal systems was not satisfactory due to a remarkable effect of competitive sorption. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Chitosan, Binary Metals, Sorption, Equilibrium, Simplified Model

Aksu, Z., Açikel, U., Kabasakal, E. and Tezer, S. (2002), Equilibrium modelling of individual and simultaneous biosorption of chromium(VI) and nickel(II) onto dried activated sludge. Water Research, 36 (12), 3063-3073.

Full Text: W\Wat Res36, 3063.pdf

Abstract: The biosorption of chromium(VI) and nickel(II) ions, both singly and in combination, by dried activated sludge was investigated in a batch system as a function of initial pH and single- and dual-metal ion concentrations. The working initial pH values for single chromium(VI) and nickel(II) biosorptions were determined as 1.0 and 4.5, respectively. It was observed that the co-ion effect on the equilibrium uptake became more pronounced as the co-ion concentration in solution increased and pH level increased for chromium(VI) and decreased for nickel(II). Adsorption isotherms were developed for both the single- and dual-metal ion systems at these two pH values and expressed by the mono- and multi-component Langmuir and Freundlich adsorption models and model parameters were estimated by the non-linear regression. It was seen that the mono-component adsorption equilibrium data fitted very well to both the monocomponent adsorption models for both the components and the pH values studied while the multi-component Freundlich adsorption model adequately predicted the multi-component adsorption equilibrium data at moderate ranges of initial mixture concentrations for both the studied pH values. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Simultaneous Biosorption, Chromium(VI), Nickel(II), Dried Activated Sludge, Mono- and Multi-Component Adsorption Models, Multicomponent Adsorption-Isotherms, Chlorella-Vulgaris, Aqueous-Solution, Heavy-Metals, Saccharomyces-Cerevisiae, Removal, Cations, Ions, Iron(III), Biomass

? Feleke, Z. and Sakakibara, Y. (2002), A bio-electrochemical reactor coupled with adsorber for the removal of nitrate and inhibitory pesticide. Water Research, 36 (12), 3092-3102.

Full Text: 2002\Wat Res36, 3092.pdf

Abstract: In this study, the treatment characteristics of nitrate and toxic pesticide by a combined bioelectrochemical reactor (BER)/adsorption process was investigated. Experimental results showed that the disappearance of NO3- in BER was in accordance with the applied current. NO2- was not detected in the effluent, but the production of NO was increased with increasing IPT loading. In the presence of IPT, up to 30% of the nitrate nitrogen consumed was converted to N2O, while more than 95% converted to N-2 in the absence of IPT. In adsorption column, IPT was efficiently removed onto either granular activated carbon or silicone resin so as to meet the guideline value (40 mug/l) and to reduce the N2O accumulation. A simplified kinetic model that considers the sequential reduction of nitrate and inhibition of the N2O reduction step by pesticide as well as Langmuir adsorption isotherm was developed and used to evaluate the process performance. Theoretically predicted effluent concentrations were in good agreement with the observed results for nitrate, nitrite, N2O, N-2 and IPT. It was considered that high removal performance of nitrate and pesticide by the combined process is attributable to high affinity of adsorbates for IPT in comparison with relatively large inhibition constant (K-i). (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Activated Carbon, Adsorption, Adsorption Isotherm, Ber, Biofilm Reactor, Column, Combined Process, Contaminated Groundwater, Denitrification, Drinking Water, Drinking-Water, Inhibition, Isotherm, Kinetic, Model, Nitrate, Nitrogen, Pesticide, Removal, Science, Treatment

Evans, J.R., Davids, W.G., MacRae, J.D. and Amirbahman, A. (2002), Kinetics of cadmium uptake by chitosan-based crab shells. Water Research, 36 (13), 3219-3226.

Full Text: W\Wat Res36, 3219.pdf

Abstract: Crushed crab shells were chemically treated to transform the chitin present into chitosan. Three particle sizes with average diameters of 0.65, 1.43 and 3.38 mm, average pore diameters ranging from 300 to 540 Å, and a specific surface area of 30 m²/g were obtained. Batch experiments were performed to study the uptake equilibrium and kinetics of cadmium by chitosan. Adsorption equilibrium followed a Freundlich relationship and was found to be independent of particle size indicating that adsorption takes place largely in the pore space. A high initial rate of cadmium uptake was followed by a slower uptake rate suggesting intraparticle diffusion as the rate-limiting step. The kinetic uptake data were successfully modeled using a pore diffusion model incorporating nonlinear adsorption. The effect of boundary layer resistance was modeled through inclusion of a mass transfer expression at the outside boundary. Two fitting parameters, the tortuosity factor () and the mass transfer coefficient at the outside boundary (k_c) were used. These parameters were unique for all solute and sorbent concentrations. The tortuosity factors varied from 1.5 for large particles to 5.1 for small particles. The mass transfer coefficient varied from 2×10^-7 m/s at 50 rpm to 2×10^-3 m/s at 200 rpm. At agitation rates below 100 rpm, boundary layer resistance reduced the uptake rate significantly. Its very high sorption capacity and relatively low production cost make chitosan an attractive sorbent for the removal of heavy metals from waste streams.

Keywords: Chitosan, Cd Removal, Heavy Metals, Sorption, Mass Transfer, Intraparticle Diffusion

Dambies, L., Vincent, T. and Guibal, E. (2002), Treatment of arsenic-containing solutions using chitosan derivatives: Uptake mechanism and sorption performances. Water Research, 36 (15), 3699-3710.

Full Text: W\Wat Res36, 3699.pdf

Abstract: Modified chitosan gel beads, which had been prepared by the molybdate adsorption and coagulation (in the presence of molybdate) methods, were tested for As(III) and As(V) removal from dilute solutions (in the range 5-20 mg As L^-1). The sorbent is very efficient at removing As(V) from acid solutions (optimum pH close to pH 2-3), whereas the sorption capacities are significantly lower for As(III) uptake (230 mg As(V) g^-1 Mo, 70 mg As(III) g^-1 Mo, respectively). Since the sorption proceeds in acidic solutions with a partial release of molybdate and with residual concentrations (ca. 500 g As L^-1) above the regulations for drinking water, the process appears to be directed to the treatment of industrial effluents or as a pre-concentration process. The mechanism of As(V) sorption is related to the ability of molybdate ions to complex As(V) ions in acid solutions. The uptake mechanism was confirmed by XPS analysis and desorption studies. In the case of As(III) sorption the mechanism of uptake is not identified since no complex has been cited in the literature regarding As(III) binding to Mo(VI), which was also identified by XPS analysis as the sorption site. As(V) sorption is not influenced by the presence of co-ions, with the exception of phosphate anions at low concentration, and silicate at high relative concentration. Arsenic desorption can be performed using phosphoric acid solutions. (C) 2002 Published by Elsevier Science Ltd.

Keywords: Chitosan Gel Beads, Molybdate, Arsenic(III), Arsenic(V), Sorption, Isotherms, Kinetics, X-Ray Photoelectron Spectroscopy, Hydrous Zirconium-Oxide, Activated Carbon, Aqueous-Solution, Ferric-Chloride, Ion-Exchange, Adsorption Characteristics, Alginate Gels, Removal, Groundwater, Bangladesh

? Sabah, E., Turan, M. and Çelik, M.S. (2002), Adsorption mechanism of cationic surfactants onto acid- and heat-activated sepiolites. Water Research, 36 (16), 3957-3964.

Full Text: 2002\Wat Res36, 3957.pdf

Abstract: Systematic adsorption tests were carried out to determine the uptake of typical quaternary amines, dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide and a primary amine, dodecylamine hydrochloride by sepiolite. Bottle adsorption tests conducted with untreated, acid- and heat-activated sepiolites exhibit two distinct regions. The first stage is characterized by low rate and governed through an ion exchange process between ammonium ions and magnesium ions in the octahedral sheet. The second stage is ascribed to a combination of chain–chain interactions through Van der Waals forces and ion exchange process. Despite several-fold increases in surface areas upon activation, surprisingly no improvement in adsorption is observed. The observed differences are explained on the basis of partial collapse of the sepiolite crystal structure, the removal of zeolitic and bound waters and modification of the pore size distribution of sepiolite upon treatments.

Keywords: Adsorption, Clay Minerals, Sepiolite, Cationic Surfactants, Amines, Waste Water Treatment

Dimitrova, S.V. (2002), Use of granular slag columns for lead removal. Water Research, 36 (16), 4001-4008.

Full Text: W\Wat Res36, 4001.pdf

Abstract: The use of granular blast furnace slag (GBFS)-packed columns to treat lead-containing solutions has been investigated. The results obtained indicated that the slag usage rate decreased with increasing flow velocity, particle size, initial lead concentration and decreasing with bed height. Lead removed selectively in the presence of other heavy metal ions. High concentrations of sodium and especially calcium in the solutions impeded the uptake of lead. For 20 mg l⁻¹ lead concentration an empty bed contact time greater of 4 min provided to efficient use of the slag bed. Column pH was an important parameter to lead removal under dynamic conditions and reflected the influence of the investigated factors. During all runs lead breakthrough coincided with an abrupt drop in effluent pH. The apparent mechanisms of lead removal in GBFS column are sorption (ion exchange and adsorption) on the slag surface and precipitation.

Keywords: Granular Slag, Lead, Fixed-Bed, Metal Ions, Removal, Sorption

? Singer, P.C. and Bilyk, K. (2002), Enhanced coagulation using a magnetic ion exchange resin. Water Research, 36 (16), 4009-4022.

Full Text: 2002\Wat Res36, 4009.pdf

Abstract: The objective of this investigation was to examine the effectiveness of a magnetic ion exchange resin (MIEX(R)) to enhance the coagulation of disinfection by-product precursors in nine surface waters, each representing a different element of the USEPA's 3 x 3 enhanced coagulation matrix. The effect of MIEX-pretreatment on the requisite alum dose needed for subsequent coagulation of turbidity was also evaluated.

Enhanced coagulation with MIEX was found to be very effective for removing trihalomethane (THM) and haloacetic acid (HAA) precursors from the nine waters examined. THM and HAA formation potential was reduced by more than 60% in all of the waters studied; reductions approaching 90% were seen in the waters with the highest specific ultraviolet absorbance values. The residual total organic carbon concentration, ultraviolet absorbance, and THM and HAA formation potential were all substantially lower as a result of MIEX and alum treatment compared to alum coagulation alone. MIEX pre-treatment also lowered the coagulant demand of each of the waters substantially. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Ion Exchange, Disinfection By-Products, Trihalomethanes, Haloacetic Acids, Total Organic Carbon, Coagulation, Coagulant Demand, Drinking-Water, Chlorination, Precursors, Removal, Products, Organics, Alum

Pagnanelli, F., Esposito, A. and Vegliò, F. (2002), Multi-metallic modelling for biosorption of binary systems. Water Research, 36 (16), 4095-4105.

Full Text: W\Wat Res36, 4095.pdf

Abstract: In this paper a specially propagated biomass of Sphaerotilus natans was tested as adsorbent for binary solutions of Cu-Cd. Cu-Pb and Cu-Zn at different equilibrium pH. The experimental results outline the buffering effect of H⁺ at low pH. which masks the competition among metals. In each binary system the biomass affinity follows the acidic properties of the heavy metals probably due to an ionic exchange mechanism operating among active sites and metals in solution. The experimental results ere fitted according to an empirical approach with growing complexity that outlines the inadequacy of the predictive models and the non-ideal interactions among metals. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Biosorption, Heavy Metal, Modelling, Multi-Metal Systems, Environment, Positive Soil Bacterium, Isolated Cell-Walls, Competitive Adsorption, Heavy-Metals, Multicomponent Adsorption, Sphaerotilus Natans, Chlorella-Vulgaris, Ion-Exchange, Binding, Cadmium

Gyliene, O., Rekertas, R. and Šalkauskas, M. (2002), Removal of free and complexed heavy-metal ions by sorbents produced from fly (Musca domestica) larva shells. Water Research, 36 (16), 4128-4136.

Full Text: W\Wat Res36, 4128.pdf

Abstract: Fly larva shells (FLS) are formed as a side product in the biological treatment of organic wastes, and chitin and chitosan produced from the FLS have been used as sorbents for heavy-metal ions. Sorbents are characterised by FT-IR measurements and pH-potentiometric titration and by determination of their surface area, and the content of main elements (C, N, P, S) and ashes. Free metal ions are sorbed best (up to 0.5-0.8 mmol g^-1) onto chitin and chitosan. The sorption ability for free metal ions of chitin decreases in the order Fe(III) > Cu(II) (Pb(II) > Zn(II). > Ni(II) > Mn(II) and that of chitosan decreases in the order Cu(II) > Mn(II) > Ni(II) > Zn(II) > Pb(II) > Fe(III). The complexed metal ions are sorbed by the FLS up to 0.2-0.4 mmol g‾¹. The sorption ability for metal ions and ligands depends on pH, concentration of complexed metal ions and the ligand species in the solution. Glycine has the retarding effect on the sorption of Ni(II) and Cu(II) ions, and EDTA enhances the Cu(II) ion sorption. Ni(II) and glycine sorption obeyed the Langmuir isotherm. The observed sorption data show the promising potentialities of the FLS for the heavy-metal removal from the solutions, containing strong complexing agents. Mechanisms for the removal of free and complexed metal ions by chitin, chitosan and the FLS have been discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Fly Larva Shells (FLS), Chitin, Chitosan, Sorption, Heavy Metals, Nickel Ions, Copper Ions, Glycine, EDTA

? Karcher, S., Kornmuller, A. and Jekel, M. (2002), Anion exchange resins for removal of reactive dyes from textile wastewaters. Water Research, 36 (19), 4717-4724.

Full Text: 2002\Wat Res36, 4717.pdf

Abstract: Sorption onto an easily regenerable sorbent in fixed bed filters would be an interesting option for removal of reactive dyes from textile wastewaters. A previous screening with model solutions (Dyes Pigm 51 (2001)111) had shown two anion exchangers (strong basic S6328a and weak basic MP62, both Bayer) to exhibit good sorption characteristics for reactive dyes. The aim of this study was to evaluate these materials more closely. Thus filter breakthrough, the behavior with original wastewater samples, and the effect of inorganic wastewater parameters as well as regeneration were studied. Breakthrough curves for both materials are relatively unfavorable with a flat gradient, but throughput until breakthrough (100-800 bed volumes) should be sufficient for technical use. With both resins dye uptake is influenced little by competition of inorganic anions (sulfate, carbonate, phosphate) and they perform well in original wastewaters. However, the weak basic type is only efficient up to pH 8. Alkaline regeneration works well for MP62, for S6328a acid regeneration works for most dyes. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Anion Exchange Resins, Reactive Dyes, Sorption, Textile Wastewater, Husk

Bosso, S.T. and Enzweiler, J. (2002), Evaluation of heavy metal removal from aqueous solution onto scolecite. Water Research, 36 (19), 4795-4800.

Full Text: W\Wat Res36, 4795.pdf

Abstract: Scolecite is a zeolite associated to basalts of the Parana Continental Igneous Province (PCIP, South America). The potential of scolecite as a new material for heavy metal removal (Pb²⁺, Cu²⁺, Zn²⁺, Ni²⁺, Co²⁺ and Cd²⁺) from aqueous solutions is evaluated. The experiments were carried out by immersion of 0.5 g of sample in solutions containing the metal ions, and kept under constant agitation for 24 h, at ambient temperature. The meq of cations retained per mass of scolecite was evaluated as a function of: initial concentration (5–60 mg L⁻¹), pH (4–6), liquid/solid ratio (200, 1000 and 2000) and particle size. The results indicated a great affinity of scolecite for Cu²⁺ with a retention value of 130 μeq g⁻¹ at pH 6, C_i = 30 mg L⁻¹ and liquid/solid ratio of 200. In the same conditions, the maximum retention measured for the other ions were 64 μeq g⁻¹ (Zn²⁺), 56 μeq g⁻¹ (Pb²⁺), 31 μeq g⁻¹ (Ni²⁺), 7.8 μeq g⁻¹ (Co²⁺) and 3.2 μeq g⁻¹ (Cd²⁺). These values increase substantially when the L/S ratio is increased. The affinity of copper and lead for scolecite is discussed based on their free ionic forms (i.e., their hydrated bivalent ions) and their hydrolysis products. The remaining ions are retained as free ions. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Cation Exchange, Heavy Metal, Natural Zeolite, Scolecite

? Prosnansky, M., Sakakibara, Y. and Kuroda, M. (2002), High-rate denitrification and SS rejection by biofilm-electrode reactor (BER) combined with microfiltration. Water Research, 36 (19), 4801-4810.

Full Text: 2002\Wat Res36, 4801.pdf

Abstract: In this study, a multi-cathode biofilm-electrode reactor (BER) combined with microfiltration (MF) was investigated using a laboratory-scale experimental apparatus for treatment of nitrate-contaminated water. The multi-cathode electrodes were composed of multiple-granular activated carbons (GACs). GACs attached to each cathode to enlarge surface area of electrodes and to attach bacteria quickly and firmly. In BER, H-2 gas is produced by applying electric current, which serves as an electron donor in biological reduction of nitrate to N-2 gas. Since some suspended solids were escaping from BER, MF membrane with plate modules and a pore size of 0.2 mum was placed after BER. Experimental results demonstrated that it was possible to operate the multi-cathode BER with high denitrification rates and hydraulic retention time (HRT) as low as HRT = 20 min. The denitrification rate was enhanced by 3-60 times in comparison with former studies. MF membrane successfully rejected the bacteria escaping from BER, so that the effluent concentration of SS was kept below 1 mg SS/l throughout the experiment. It was also possible to operate MF membrane at flux 2-9 times higher and pressure 2.5-31 times smaller than in former studies. This higher performance was mainly brought about by using biofilm and H-2 gas as an electron donor. Also, an economic evaluation of BER/MF was included, showing the feasibility of this process. The present BER/MF process is considered advantageous for the enhanced treatment of nitrate-polluted groundwater. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Denitrification, Microfiltration, Multi-Electrode System, BER, Groundwater, Electrolysis, Nitrate-Contaminated Groundwater, Membrane Separation, Performance, System

Kozlowski, C.A. and Walkowiak, W. (2002), Removal of chromium(VI) from aqueous solutions by polymer inclusion membranes. Water Research,