Personal Research Database

Full Text: W\Wat Res32, 969.pdf

Abstract: Adsorption of metal ions such as Pb(II), Ni(II) and Cd(II) onto ‘waste’ Fe(III)/Cr(III) hydroxide was studied both in the presence and absence of ligands such as ethylenediamine tetraacetic acid, citrate and acetate. All three ligands decreased the adsorption of Pb(II) in the pH range 3.5 to 8.5. Citrate and EDTA considerably decreased the adsorption of NI(II) but acetate showed a slight increase in adsorption. Cadmium adsorption decreased significantly in the presence of acetate and citrate.

Keywords: Complexing Ligands, Adsorption, Water, Cadmium, Adsorption, Metal Ions, Fe(III)/Cr(III) Hydroxide, Ligands

López-Delgado, A., Pérez, C. and López, F.A. (1998), Sorption of heavy metals on blast furnace sludge. Water Research, 32 (4), 989-996.

Full Text: W\Wat Res32, 989.pdf

Abstract: An investigation into the use of sludge, a by-product of the steel industry, as an adsorbent for the removal of heavy metals from liquid effluents was carried out. Gases produced in the blast furnace were washed and led towards a Dorr thickener where the sludge was obtained as a suspension. The sorption of Pb²⁺, Zn²⁺, Cd²⁺, Cu²⁺ and Cr³⁺ on the sludge was investigated by determination of adsorption isotherms. The effects of time, equilibrium temperature and concentration of metalsolution on sludge adsorption efficiency was evaluated. The adsorption process was analyzed using the theories of Freundlich and Langmuir and the thermodynamic values of Delta G, Delta H and Delta S corresponding to each adsorption process were calculated. Blast furnace sludge was found to be an effective sorbent for Pb, Zn, Cd, Cu and Cr-ions within the range of ion concentrations employed.

Keywords: Aqueous-Solution, Adsorption, Ions, Adsorption, Heavy Metals, Industrial Effluents, Blast Furnace Sludge, Waste

Ivancev-Tumbas, I., Dalmacija, B., Tamas, Z. and Karlovic, E. (1998), Reuse of biologically regenerated activated carbon for phenol removal. Water Research, 32 (4), 1085-1094.

Full Text: W\Wat Res32, 1085.pdf

Abstract: Granular biologically activated carbon (GBAC) is in principle suited for removal of phenolic substrate from wastewater. In this study a wastewater model was used and special attention was paid to the operation of separate aerobic bioregeneration of carbon and reuse of bioregenerated carbon in a new stage of the experiment. In order to assess the effectiveness of bioregeneration, the efficiency of the biosorption system both before and after its bioregeneration was monitored at the substrate concentrations ranging from 1.9 to 1053 mgl^-1. All kinetic parameters for the biosorption system were determined for both fresh and already used GBAC. A 92-100% efficiency of phenol removal was achieved irrespective of whether the fresh or bioregenerated GBAC was used. The process of bioregeneration for the once-used GBAC was faster than for the one that was used several times. It was also faster when phenol alone was used as substrate than in the case of a phenol mixture. Respirometric measurements indicated that a mixture of substituted phenols showed inhibition effects on microorganisms. Calculations based on these measurements, as well as the findings of GC/MS analysis. indicated that deterioration of the adsorbent quality was taking place continuously. It was concluded that bioregeneration, carried out as a separate operation, could not be recommended for practice.

Keywords: Substituted Phenols, Waste-Water, Adsorption, Biosorption, Degradation, Bioregeneration, Granulated Biologically Activated Carbon, Phenol, Biodegradation, Respirometry, Biosorption

Zhou, M.L., Martin, G., Taha, S. and, Sant’Anna, F. (1998), Adsorption isotherm comparison and modelling in liquid phase onto activated carbon. Water Research, 32 (4), 1109-1118.

Full Text: W\Wat Res32, 1109.pdf

Abstract: Activated carbon is used in many processes for the treatment of aqueous solutions or the cleaning of industrial waste water. If we want to know the dimension of a reactor, using an adsorbant material, it is necessary to provide the capacity and rate of adsorption. The study of the adsorption equilibrium allows the estimation of the material capacity to adsorb various molecules. The representation of adsorption isotherm onto activated carbon can be based on models with two, three or even more parameters. Nevertheless, when solute concentrations vary over many orders of magnitude (e.g. 10^-4 to 20 mmol.l^-1) (Snoeyink et at, 1969; Jossens et nl., 1978), the equations with two parameters cannot match the experimental results. Meanwhile, the equations with three parameters (Redlich and Peterson, 1959; Jossens er nl., 1978) match the experimental results better (Radke and Prausnitz, 1972; Mathews and Su, 1983).

The aim of this work is to compare the different adsorption isotherms in solution For aromatic compounds (nitrobenzene, benzaldehyde, nitro-4-phenol, 4-cresol, phenol and aniline) onto activated carbon Picactif NC60. Four representations of models with 2 or 3 parameters are discussed. The models with two parameters (Langmuir, 1915; Freundlich and Heller, 1939) fit experimental data over a narrow solute concentration range (Figs 3 and 4). For the Langmuir equation, the linear method has an effect on the estimation of isotherm parameters and simulation precision (Tables 1 and 2).

The values of q(m) obtained by linear method (I) are always lower than the values obtained by linear method (ir). On the other hand, the values of parameter b obtained by linear method (I) are higher than the values obtained by linear method (II). The method (I) leads to a higher absolute, standard deviation and a lower relative standard deviation, than those obtained by linear method (II). Therefore, linear methods (I) and (II) are unsuitable because neither of them takes the measurement range into account.

For a wide concentration range, models with three parameters (Redlich-Peterson and Jossens-Myers) correlate better to experimental results (Figs 5 and 6). Since if is based on the values of standard deviation (Table 2) for the studied molecules, the equation of Jossen-Myers is slightly better than the Redlich-Peterson one. According to these isotherm equations and calculated results (Table 3), we can give an average order of adsorbability for the studied compounds: (nitrobenzene > benzaldehyde > nitro-4-phenol > 4-cresol > phenol > aniline).

Keywords: Adsorption Isotherm, Model, Activated Carbon, Aromatic Compounds, Chromatography, Surface

Daifullah, A.A.M. and Girgis, B.S. (1998), Removal of some substituted phenols by activated carbon obtained from agricultural waste. Water Research, 32 (4), 1169-1177.

Full Text: W\Wat Res32, 1169.pdf

Abstract: Equilibrium removal of phenol (P), m-, p-Cresol (Cr), 2- chlorophenol (2-CP), 4-nitrophenol (4-NP), 2,4-dichlorophenol (2,4-dCP), and 2,4-dinitrophenol (2,4-dNP) was tested by adsorption onto activated carbon prepared from apricot stone shells by chemical treatment with H3PO4 Disubstituted phenols are adsorbed in larger amounts than monosubstituted ones. No clear correlation seems to hold between the amount removed and texture characteristics of the sorbent. Uptake of phenols increases in the order P, Cr < 2-CP < 4-NP < 2,4-dNP < 2,4-dCP, which correlates well with respective increase in molecular dimensions and acidity and decrease in solubility of the sorbates. Abnormality shown by 2,4-dNP as a drop in its removal, is due to strong adsorption at the entrace or inside certain pores thus limiting Further diffusion of solute molecules and/or probable molecular sieve effect. (C) 1998 Elsevier Science Ltd. All rights reserved.

Nowack, B. (1998), The behavior of phosphonates in wastewater treatment plants of Switzerland. Water Research, 32 (4), 1271-1279.

Full Text: W\Wat Res32, 1271.pdf

Abstract: The behavior of three phosphonates in seven Swiss wastewater treatment plants was investigated. The phosphonates ATMP (aminotrismethylene-phosphonic acid) and EDTMP (ethylenediamine-tetramethylenephosphonic acid) were found in the influents of wastewater treatment plants at concentrations between <0.05 µmoll^-1 (detection limit) and 0.8 µmoll^-1, DTPMP (diethylenetriamine-pentamethylenephosphonic acid) from <0.05 to 2 µmoll^-1. The highest concentration was found in the influent of a wastewater treatment plant with significant input from the textile industry. The effluent of this wastewater treatment plant contained an average DTPMP concentration of 0.12 µmoll^-1, which reflects a 85% decrease from the influent concentration. The phosphonate concentrations in all other effluents were below detectable levels. As phosphonates are not biodegradable, the elimination must be due to sorption processes. The phosphonates are almost quantitatively transferred to the anaerobic digester. The investigation of the anaerobic degradation showed no evidence for mineralization. Compared to EDTA (ethylenediaminetetraacetic acid) which is not eliminated during wastewater treatment, phosphonates have less impact on the metalspeciation in natural waters.

Keywords: Environmental Fate, Sludge Adsorption, Degradability, Speciation, Mobility, Water, Soils, EDTA, Phosphonates, Atmp, Edtmp, Dtpmp, EDTA, Sewage Treatment, Elimination, Anaerobic Degradation, Environmental Impact

Gonçalves, E.P. and Boaventura, R.A.R. (1998), Uptake and release kinetics of copper by the aquatic moss Fontinalis antipyretica. Water Research, 32 (4), 1305-1313.

Full Text: W\Wat Res32, 1305.pdf

Abstract: Copper uptake and release rates by Fontinalis antipyretica were investigated. A contamination stage in which the plants were exposed to Cu concentrations in the range 0.09-0.75 mg l^-1 was followed by a decontamination period, exposing the plants to metal-free water. Tanks were operated in perfectly mixed conditions and the illumination at water surface was 740 lux. Short and long duration experiments (217 and 1008 h, respectively) were carried out with plants collected in May and August, respectively. A simple mass transfer model was fitted to the experimental results in order to determine the uptake and release rate constants, k₁ and k₂, the Cu concentration at the end of the uptake phase, C-mu, and the equilibrium concentrations, C-me and C-mr, for the contamination and decontamination stages, respectively. In the short duration experiment, k₁ decreased from 846 to 628 h^-1 as Cu concentration increased from 0.14 to 0.60 mg l^-1 In the long duration one, with plants in different physiological conditions, k(1) decreased From 448 to 293 h^-1 as Cu concentration increased from 0.09 to 0.75 mg l^-1. The release rate constant, k₂, appears not to depend on the Cu concentration and averaged 0.020 and 0.011 h^-1 in the first and second experiments, respectively. The ratio k₁/k₂ represents a bioconcentration factor, BCF (Cu concentration in the plant, dry wt/Cu concentration in the water). BCF values ranged between 40,000 and 30,000. A biological elimination factor

(BEF = 1-(C-mr/C-mu)

was also calculated. BEF values slightly increased with C-mu, varying from 0.58 to 0.62 (5203 < C_µ< 15762 mg kg^-1 dry wt.) and from 0.46 to 0.66 (3127 < C_µ <23773 mg kg^-1 dry wt.) in the short and long duration experiments, respectively. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: River Basin Portugal, Heavy-Metals, Rhynchostegium-Riparioides, Waste-Water, Accumulation, Pollution, Bryophytes, Plants, Sediments, Chromium

López, E., Soto, B., Arias, M., Núñez, A., Rubinos, D. and Barral, M.T. (1998), Adsorbent properties of red mud and its use for wastewater treatment. Water Research, 32 (4), 1314-1322.

Full Text: W\Wat Res32, 1314.pdf

Abstract: With a view to simultaneously conserving the environment and an important natural resource, we assessed the feasibility of using red mud (RM), a residue from bauxite refining, for wastewater treatment. Moistened mixtures of RM and 8% (w/w) CaSO₄ form aggregates which are stable in aqueous media. Batch experiments examining adsorption of phosphorus (P) by these aggregates for contact times of 3, 6, 24 and 48 h indicated that adsorption occurred by both fast and slow reactions. Likewise, comparison of experimental breakthrough curves (BTCs) for P retention on a column of RM aggregates (residence time 3 h) with MCMFIT-simulated BTCs indicated that fast and slow adsorption reactions were occurring. Actual P retention was predicted, taking into account both kinetics of fast and slow adsorption reactions. The RM aggregates had maximum adsorption capacities (evaluated from fits (0.90 < R² < 0.99) of the Langmuir isotherm to batch adsorption data for contact time 48 h) for Cu²⁺, Zn²⁺, Ni²⁺ and Cd²⁺ of 19.72, 12.59, 10.95 and 10.57 mpg^-1, respectively. In continuous adsorption experiments in which secondary effluent from an urban sewage treatment plant was percolated through RM aggregates packed into columns, purification efficiencies for P, Ni²⁺, Cu²⁺ and Zn²⁺ were 100, 100, 68 and 56% respectively. Aggregated RM is suitable for treatment of wastewaters, in particular those whose principal contaminants are P or heavy metals.

Keywords: Sewage Effluent, Amended Sand, Equilibrium, Phosphorus, Removal, Columns, Red Mud, Aggregation, Adsorption, Metals, Phosphorus, Column Experiments, Wastewater, Purification

Cabrero, A., Fernandez, S., Mirada, F. and Garcia, J. (1998), Effects of copper and zinc on the activated sludge bacteria growth kinetics. Water Research, 32 (5), 1355-1362.

Full Text: W\Wat Res32, 1355.pdf

Abstract: A simple experimental set-up has been proposed to study the influence of Cu(II) and Zn(II) on the activated sludge growth kinetics by following the rate of change on biomass concentration during batch growth experiments. Data on biomass were fitted to a sigmoidal equation providing us the main biokinetics parameters (Y-xs, and m). Inocula seeded to the system was obtained from a wastewater treatment plant operating at 14 days cell residence time. A synthetic feed solution containing 2000 mg/l gelatin (corresponding to 1630 mg/l COD) served as source of carbon. Different concentrations of Cu(II) and Zn(II) (1, 5, 10 and 20 mg/l) were introduced singly in the reactors keeping all environmental parameters constant (pH, T-a, basic nutrients). The combined effects of Cu(II) and Zn(II) were determined by mixing these metallic ions (5/5, 5/10, and 10/5 mg/l of Cu(II)/Zn(II) respectively). Experimental data showed that Zn(II) was less toxic than Cu(II), as expressed by a slight stimulating effect for 1 mg/l Zn(II). Moreover, biokinetic parameters were nor adversely affected by the presence of Cu(II) up to a concentration of 5 mg/l. However, a concentration of 10 mg/l and higher, caused serious upsets in the system. Combined effects of copper and zinc on the activated sludge growth kinetics, indicated that these two heavy metals acted neither synergistically nor antagonistically. The sigmoidal model very well fits the experimental data and could be used in a simulation study. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Activated Sludge, Growth Kinetics, Heavy Metals, Wastewater, Sigmoidal Equation, Cu(II), Models

Tobin, J.M. and Roux, J.C. (1998), Mucor biosorbent for chromium removal from tanning effluent. Water Research, 32 (5), 1407-1416.

Full Text: W\Wat Res32, 1407.pdf

Abstract: Waste industrial Muco, meihi biomass was found to be an effective biosorbent for the removal of chromium from industrial tanning effluents. Sorption levels of 1.15 and 0.7 mmol/g were observed at pH 4 and 2 respectively while precipitation effects augmented these values at higher pH ranges. Acid elution of biosorbed chromium increased with decreasing eluant pH to a maximium value of ca. 30% at approximately zero pH. Successive elution stages with increasingly strong acids resulted in a cumulative chromium recovery of in excess of 80%. Both acid and base treatments eluted biosorbed chromium and successive acid/base and base/acid treatments resulted in recovery values approaching 100% at low metal loadings. These values decreased to 80 to 60% at higher biomass metal loadings. in comparative studies with ion exchange resins, the Mucor biomass demonstrated chromium biosorption levels that correspond closely to those of commercial strongly acidic exchange resin while the pH behaviour mirrored that of the weakly acidic resins in solution. The chromium elution characteristics from the Mucor biomass were similar to those of both the weakly and strongly acid resins. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Chromium, Biosorption, Fungal Biomass, Tanning Effluent, Metal Uptake, Mucor Biosorbent, Rhizopus-arrhizus Biomass, Saccharomyces-cerevisiae, Metal-Ions, Biosorption, Copper, Adsorption, Mechanisms, Desorption, Recovery, Cadmium

Zhang, L., Zhao, L., Yu, Y.T. and Chen, C.Z. (1998), Removal of lead from aqueous solution by non-living Rhizopus nigricans. Water Research, 32 (5), 1437-1444.

Full Text: W\Wat Res32, 1437.pdf

Abstract: Non-living Rhizopus nigricans obtained as waste byproduct from the pharmaceutical fermentation industry has been used for adsorption of lead over a range of metal ion concentrations, adsorption time, pH and co-ions. The process of uptake obeys both the Langmuir and Freundlich isotherms. The mechanism of lead sequestering by this type of biomass was also studied by using experimental techniques such as electron microscopy, X-ray energy dispersion analysis and IR spectroscopy. Comparison of uptake between NaOH-treated and untreated biomass shows that the adsorption takes place in the chitin structure of the cell wall.

Keywords: Biosorption, Uranium, Rhizopus nigricans, Lead Ion, Adsorption, Mechanism

Min, J.H. and Hering, J.G. (1998), Arsenate sorption by Fe(III)-doped alginate gels. Water Research, 32 (5), 1544-1552.

Full Text: W\Wat Res32, 1544.pdf

Abstract: Although cationic metal contaminants can be effectively removed From wastewaters by treatment with biopolymers, application of biopolymers for the removal of anionic contaminants (such as As, Cr(VI), and Se) has been limited. The objective of this study was to examine the fundamental aspects of a possible remediation strategy for removal of anionic metalspecies employing the biopolymer alginic acid pretreated with Ca and Fe(III). Spherical gel beads (2 mm in diameter) were formed by dispensing the biopolymer solution dropwise into 0.1 M CaCl₂; Ca beads were then washed and equilibrated with 0.1 M FeCl₃ to achieve partial substitution of Fe(III) for Ca. The resulting Ca-Fe beads were found to be effective at removing As(V) from solution on a time scale of approximately 100 h. As(V) sorption was pH dependent; optimal removal and stability of the Ca-Fe beads was achieved at pH 4. At a given initial As(V) concentration, As(V) removal efficiency increased with increasing Fe content (number of beads); at an initial As(V) concentration of 400 µg/l, up to 94% removal was achieved at pH 4 after 120 h. For a given Fe content, uptake of As(V) increased with increasing initial As(V) concentration until saturation was reached. Sorption data was modeled using a single type of As(V) binding site. Data on As(V) sorption as a function of dissolved As(V) concentration and Fe content were used to obtain and validate the site density and conditional affinity constant for As(V) sorption.

Keywords: Physicochemical Properties, Semiconductor Industry, Waste Generation, Activated Carbon, Beads, Removal, Equilibrium, Adsorption, Recovery, Reactor, Oxyanion, Arsenic, Arsenate, Biopolymer, Alginate, Gel Bead, Fe(III)-Doped, Removal, Wastewaters

Uranowski, L.J., Tessmer, C.H. and Vidic, R.D. (1998), The effect of surface metal oxides on activated carbon adsorption of phenolics. Water Research, 32 (6), 1841-1851.

Full Text: W\Wat Res32, 1841.pdf

Abstract: The adsorptive capacity of granular activated carbon (GAC) for many phenolic compounds has been found to increase in the presence of molecular oxygen (oxic condition). This enhanced adsorption is due to oxidative coupling of the adsorbed molecules and is accompanied by significant oxygen consumption and decreased adsorbate recovery by solvent extraction. The present study investigated the possible catalytic effect of metals and metal oxides on activated carbon surface for this reaction. The ash and metal content of seven GACs were compared to the enhanced adsorption found under the oxic conditions, oxygen consumption during adsorption and adsorbate recovery. No correlation between ash or metal content and these parameters was found. Reduction of metal content by acid washing did not impact the adsorptive properties of the carbon. In addition, a carbonaceous resin impregnated with metal oxides of copper, iron and manganese showed no ability to promote oxidative coupling of phenolics. The results of this study suggest that acid-washable metals and metal oxides that are present on the surface of activated carbon are not a key factor in promoting oligomerization of adsorbates in the presence of oxygen.

Kapoor, A. and Viraraghavan, T. (1998), Removal of heavy metals from aqueous solutions using immobilized fungal biomass in continuous mode. Water Research, 32 (6), 1968-1977.

Full Text: W\Wat Res32, 1968.pdf

Abstract: Fungal microorganisms are being increasingly studied for the removal of heavy metal ions from aqueous solutions. The fungal biomass in powdered form is commonly used in metal adsorption studies. The use of powdered biomass can pose problems in its application in batch and continuous (column) type reactors treating wastewaters because fungal biomass becomes soft in contact with water, has low density, is difficult to separate from treated wastewater and fixed bed reactors using it can easily clog. Immobilization of fungal biomass in a solid polymer matrix will facilitate their application in industrial systems treating heavy metal bearing wastewater. In this study, A. niger biomass was immobilized in a polysulfone matrix. For this purpose an immobilizing unit was fabricated to produce an immobilized biomass matrix of spherical shape. The beads were found to have a porous structure. Majority of the beads had particle sizes in the range of 2.00 to 0.841 mm. The biomass beads packed in a column were able to remove metal ions such as cadmium, copper, lead and nickel. The breakthrough data obtained for cadmium, copper, lead and nickel was adequately described by the Thomas adsorption model. The amounts of metal adsorbed per unit weight of beads for cadmium, copper, lead and nickel were 3.60, 2.89, 10.05, and 1.08 mg/g respectively. The adsorbed metal ions were easily eluted from the column using 0.05N nitric acid. These beads may be easier to use in industrial wastewater treatment systems in comparison with the fungal biomass powder.

Keywords: Cadmium, Ions, Biosorbents, Biosorption, Wastewaters, Parameters, Sorption, Cu(II), Aspergillus niger, Adsorption, Immobilization, Cadmium, Copper, Lead, Nickel, Desorption

Yoon, S.H., Lee, C.H., Kim, K.J. and Fane, A.G. (1998), Effect of calcium ion on the fouling of nanofilter by humic acid in drinking water production. Water Research, 32 (7), 2180-2186.

Full Text: W\Wat Res32, 2180.pdf

Abstract: The influence of the charge of humic acid (HA) on the fouling of nanofilters was investigated as a Function of pH and concentration of calcium ions. The charge of the humic acid as well as the zeta-potential of the membrane surface were measured to elucidate the mechanism of humic acid deposition on the membrane surface. The negative charge of humic acid as well as the negative zeta-potential of the membrane surface fouled with humic acid increased with higher pH. As a result the further deposition of humic acid on the membrane surface was expected to decrease with higher pH because of larger repulsive forces. With moderate calcium ion concentration, however, the adsorption of humic acid onto the membrane surface decreased until neutral pH and then increased again. It was attributed to calcium ion bridging between two free functional groups of humic acids. Calcium ion rejection decreased in the presence of humic acid deposited on membrane surface. This could be explained by the effect of humic acid on the net charge of the membrane. The addition of calcium chelating agent, EDTA, improved flux, especially at alkaline conditions. The diagram of Ca-EDTA vs pH was used to explain the flux improvement. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Ultrafiltration Membranes, Substances, Adsorption, Diffusion, Humic Acid, Nanofiltration, Calcium Ion, Zeta-Potential, EDTA

Tütem, E., Apak, R. and Ünal, Ç.F. (1998), Adsorptive removal of chlorophenols from water by bituminous shale. Water Research,