Personal Research Database

Full Text: 2002\Wat Res36, 1397.pdf

Abstract: This paper reviews the progress in preparing and using ferrate(VI) salt as an oxidant and coagulant for water and wastewater treatment. The literature revealed that due to its unique properties (viz. strong oxidizing potential and simultaneous generation of ferric coagulating species), ferrate(VI) salt can disinfect microorganisms, partially degrade and/or oxidise the organic and inorganic impurities, and remove suspended/colloidal particulate materials in a single dosing and mixing unit process, However, these findings have not yet lead to the full-scale application of ferrate(VI,) in the water industry owing to difficulties associated with the relatively low yield of ferrate(VI), the instability of the chemical depending on its method of preparation, and the lack of adequate studies that have demonstrated its capabilities and advantages over existing water and wastewater treatment methods. Fundamental study is thus required to explore the new preparation methods focusing on increasing the production yield and product’s stability and avoiding using hypochlorite or chlorine as the oxidant. Also, the application of ferrate(VI) in drinking water treatment has not been studied systematically and future work in this field is recommended. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Water Treatment Chemicals, Ferrate(VI) Salts, Potassium Ferrate, Coagulant, Disinfectant, Oxidant, Wastewater Treatment, Anodic Iron Dissolution, Alkali Hydroxide Solutions, White Cast-Iron, Potassium Ferrate, Current Efficiency, Current Yields, Electrochemical Generation, Pulse-Radiolysis, Amino-Acids, Pure Iron

Notes: highly cited

? Fromme, H., Küchler, T., Otto, T., Pilz, K., Müller, J. and Wenzel, A. (2002), Occurrence of phthalates and bisphenol A and F in the environment. Water Research, 36 (6), 1429-1438.

Full Text: 2002\Wat Res36, 1429.pdf

Abstract: Certain xenoestrogens, namely bisphenol A (BPA), bisphenol F (BPF), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP), and di(2-ethylhexyl)phthalate (DEHP), were measured in various compartments (surface water, sediments, sewage treatment plant effluents, sewage sludge, dump water, liquid manure) in order to contribute to a better understanding of exposure to these compounds in different environments.

Hundred and sixteen surface-water samples and 35 sediments from rivers, lakes and channels, 39 sewage effluents, and 38 sewage sludges were collected in Germany. Furthermore, ten liquid manure, two waste-dump and two compost-runoff water samples were also analysed.

BPA measurements showed low concentrations from 0.0005 to 0.41 mug L-1 in surface water, in sewage effluents from 0.018 to 0.702 mugL(-1), in sediments from 0.01 to 0.19 mg kg(-1) and in sewage sludge from 0.004 to 1.363 mg kg(-1) dw. Measured concentrations of BPF were clearly lower than BPA in all environmental media.

DEHP dominated the phthalate concentrations, which ranged from 0.33 to 97.8 mugL(-1) (surface water), 1.74 to 182 mug L-1 (sewage effluents), 27.9 to 154 mg kg(-1) dw (sewage sludge) and 0.21 to 8.44 mg kg(-1) (sediment). DBP was found only in minor concentrations and BBP, only in a few samples in low amounts. Very high concentrations of BPA and phthalates were confirmed in waste dump water and compost water samples as well as in the liquid manure samples. (C) 2002 Published by Elsevier Science Ltd.

Keywords: Xenoestrogen, Bisphenol A, Bisphenol F, Phthalate, Di(2-Ethylhexyl)Phthalate, Dibutyl Phthalate, Surface Water, Sediment, Sewage Treatment Plant Effluent, Sewage Sludge, Liquid Manure, Dump Water, Esters, Water, Separation, Pesticides, Samples, River, Fate

Al-Shamrani, A.A., James, A. and Xiao, H. (2002), Destabilisation of oil-water emulsions and separation by dissolved air flotation. Water Research, 36 (6), 1503-1512.

Full Text: W\Wat Res36, 1503.pdf

Abstract: The roles of aluminium and ferric sulphates as destabilising agents for oil-water emulsions that have been stabilised by a non-ionic surfactant (Span 20) are investigated in terms of oil removal. The effects of coagulant dose, pH, and the duration and intensity of both slow and fast mixing are considered. Electrokinetic measurements indicate that oil droplets have a negative zeta potential that is weakly dependent on pH. The chosen coagulants are shown to be effective in reducing the zeta potential of the oil droplets, and charge reversal was observed for aluminium sulphate. Oil removals up to 99.3% at pH 8 and 99.94% at pH 7 are seen for aluminium sulphate and ferric sulphate respectively. Rapid mixing times of around 120s and flocculation times ranging from 15 to 20 min appear to be optimal for the DAF separation. It is concluded that relatively low average mixing speeds for coagulation and flocculation are essential for efficient operation. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Emulsion, Flocculation, Flotation, Industrial Wastewater, Zeta Potential, Coagulation, Flocculation, Optimization, Removal

Manohar, D.M., Krishnan, K.A. and Anirudhan, T.S. (2002), Removal of mercury(II) from aqueous solutions and chlor-alkali industry wastewater using 2-mercaptobenzimidazole-clay. Water Research, 36 (6), 1609-1619.

Full Text: W\Wat Res36, 1609.pdf

Abstract: The 2-mercaptobenzimidazole loaded natural clay was prepared for the removal of Hg(II) from aqueous media. Adsorption of the metal ions from aqueous solution as a function of solution concentration. agitation time, pH, temperature, ionic strength, particle size of the adsorbent and adsorbent dose was studied. The adsorption process follows a pseudo-second-order kinetics. The rate constants as a function of initial concentration and temperature were Given. The adsorption of Hg(II) increased with increasing pH and reached a plateau value in the pH range 4.0-8.0. The removal of Hg(II) was found to be >99% at an initial concentration of 50mg/l. Mercury(II) uptake was found to increase with ionic strength and temperature. Further, the adsorption of Hg(II) increased with increasing adsorbent dose and decrease with adsorbent particle size. Sorption data analysis was carried out using Langmuir and modified Langmuir isotherms for the uptake of metal ion in an initial concentration range of 50-1000 mg/l. The significance of the two linear relationships obtained by plotting the data according to the conventional Langmuir equation is discussed in terms of the binding energies of the two population sites involved which have a widely differing affinity for Hg(H) ions. Thermodynamic parameters such as changes of free energy, enthalpy, and entropy were calculated to predict the nature of adsorption. It was found that the values of isosteric heat of adsorption were varied with surface loading. The chlor-alkali industry wastewater samples were treated by MBI-clay to demonstrate its efficiency in removing Hg(II) from wastewater. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Adsorption Kinetics, Langmuir Isotherm, Hg(II) Removal, 2-Mercaptobenzimidazole-Clay, Thermodynamic Parameters, Wastewater, Heavy-Metal Ions, Coconut Husk, Adsorption, Cadmium, Water, Kinetics, Sorption, Carbon, Hg(II), pH

Rengaraj, S. and Moon, S.H. (2002), Kinetics of adsorption of Co(II) removal from water and wastewater by ion exchange resins. Water Research, 36 (7), 1783-1793.

Full Text: W\Wat Res36, 1783.pdf

Abstract: The capacity of ion exchange resins, IRN77 and SKN1, for removal of cobalt from aqueous solution has been investigated under different conditions namely initial solution pH, initial metal-ion concentration, and contact time. The equilibrium data obtained in this study have been found to fit both the Langmuir and Freundlich adsorption isotherms. The adsorption of Co(II) on these resins follows first-order reversible kinetics. The film diffusion of Co(II) in these ion exchange resins was shown to be the main rate limiting step. The studies showed that these cation exchange resins can be used as efficient adsorbent material for the removal of Co(II) from aqueous solutions. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Cobalt(II), Ion Exchange Resin, Adsorption Isotherms, Adsorption Kinetics, Wastewater, Activated Carbon, Aqueous-Solution, Lead

Nakajima, A. (2002), Electron spin resonance study of copper biosorption by bacteria. Water Research, 36 (8), 2091-2097.

Full Text: W\Wat Res36, 2091.pdf

Abstract: The biosorption of copper by bacteria was studied by using ESR spectroscopy. Among bacteria tested, Arthrobacter nicotianae has the most excellent ability to sorb copper. The biosorption of copper by Arthrobacter cells was so rapid, affected by the solution pH, and obeys the Langmuir adsorption equilibrium. The electron spin resonance (ESR) spectra of Cu(II) in bacterial cells are axial type, having a major absorption to higher field at g and lesser absorption to lower field at g_║ with four lines. The ESR parameters showed that Cu(II) in the cells has the tetragonally distorted octahedral structure with nitrogen and oxygen as ligand atoms, which suggests that most of copper in bacterial cells combined with amino acid residues in the cell surface proteins. The variation of spectral patterns among bacteria could explain as the change of ligand circumstances caused by the pH of the cell surface. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Copper Biosorption, ESR of Cu(II) Ion, Arthrobacter Nicotianae

Ringqvist, L. and Öborn, I. (2002), Copper and zinc adsorption onto poorly humified Sphagnum and Carex peat. Water Research, 36 (9), 2233-2242.

Full Text: W\Wat Res36, 2233.pdf

Abstract: Peat generally has a high adsorption capacity and has been suggested as an adsorbent for metals in polluted waters. However, the adsorption potential of peat can be expected to be strongly dependent on the chemical properties of the water. In this study, the effect of pH, ionic strength (CaCl₂ and NaCl concentrations), and metal concentration on Cu and Zn adsorption onto poorly humified Sphagnum and Carex peat was investigated in batch experiments using a fractional factorial experimental design. The pH value was varied between 4 and 8, the CaCl₂ and NaCl concentrations between 1.2–6.2 and 0.4–43 mM, respectively, and the Cu and Zn concentrations between 0.05 and 0.5 mM. The amount of Zn adsorbed increased more with increasing pH than the amount of Cu adsorbed. The effect of NaCl/CaCl₂ concentration was minor. It was found that Zn adsorption in particular, but also Cu adsorption, increased more with pH onto Carex peat than onto Sphagnum peat. In the pH interval 4–8, the removal of Zn from the solution increased from 0% to 80% using Carex peat and from 10% to 65% using Sphagnum peat as the adsorbent. The Carex peat sample decreased the Cu concentration by 80% at pH 4 and by 95% at pH 8 and for Sphagnum peat a decrease of 85% was maintained in the pH range investigated. The differences between Sphagnum and Carex peat were attributed to the habitat conditions at the time of peat formation. Carex peat has higher ash, nitrogen and sulphur concentrations, while Sphagnum peat contains a higher amount of uronic acid.

In treating polluted waters with peat, a higher degree of metal removal can be expected at high pH values than at low. The removal of Cu, which has a high affinity to the peat surface, was less dependent on pH than Zn removal. Poorly humified Carex peat should be chosen in treating wastewaters high in pH. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Sphagnum Peat, Carex Peat, Heavy Metal, Adsorption, Zinc, Copper, pH, Ionic Strength

Notes: highly cited

Mohan, D. and Singh, K.P. (2002), Single- and multi-component adsorption of cadmium and zinc using activated carbon derived from bagasse: An agricultural waste. Water Research, 36 (9), 2304-2318.

Full Text: W\Wat Res36, 2304.pdf

Abstract: The use of low-cost activated carbon derived from bagasse, an agricultural waste material, has been investigated as a replacement for the current expensive methods of removing heavy metals from wastewater, With a view to find a suitable application of the material, activated carbon has been derived, characterized and utilized for the removal of cadmium and zinc. The uptake of cadmium was found to be slightly greater than that of zinc and the sorption capacity increases with increase in temperature. The adsorption studies were carried out both in single- and multi-component systems. Adsorption data on derived carbon follows both the Freundlich and Langinuir models. The data are better fitted by the Freundlich isotherm as compared to Langmuir in both the single- and multi-component systems. Isotherms have been used to obtain the thermodynamic parameters. The kinetics of adsorption depends on the adsorbate concentration and the physical and chemical characteristics of the adsorbent. Studies were conducted to delineate the effect of temperature, initial adsorbate concentration, particle size of the adsorbent and solid-to-liquid ratio. On the basis of these studies, various parameters such as mass transfer coefficient, effective diffusion coefficient, activation energy and entropy of activation were evaluated to establish the mechanisms. It was concluded that the adsorption occurs through a film diffusion mechanism at low as well as at higher concentrations. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Activated Carbon, Activation, Adsorbent, Adsorption, Aqueous-Solutions, Bagasse, By-Products, Cadmium, Cadmium and Zinc Removal, Freundlich Isotherm, Heavy Metals, Heavy-Metals, Isotherm, Langmuir, Metal-Ions, Metals, Peat, Pine Bark, Removal, Solid Waste Utilization, Sorption, Waste, Wastewater Treatment, Water Treatment, Zinc

Ringqvist, L., Holmgren, A. and Öborn, I. (2002), Poorly humified peat as an adsorbent for metals in wastewater. Water Research, 36 (9), 2394-2404.

Full Text: W\Wat Res36, 2394.pdf

Abstract: Metal adsorption and surface charge determinations were performed previously on well-characterised Sphagnum and Carex peat samples. The aim of this investigation was to determine metal adsorption from complex wastewaters onto these peat samples and compare it to the adsorption onto peat granules, clinoptilolite, glauconite and a flue dust from steel production. A sulphide mine leachate, a landfill leachate and a laundry wastewater were chosen, giving a variation in pH, ionic strength, total organic carbon and concentrations of metals. Metal adsorption was determined in batch and column experiments. The wastewater composition was of great importance for metal removal efficiency, mainly due to the difference in dominating metal species. In the sulphide mine leachate, containing free metal ions, a high metal adsorption was observed onto both peat and inorganic adsorbents. In the landfill leachate the metals formed carbonate and organic complexes and a low metal removal was achieved. Contrary to the leachates, the laundry wastewater contained suspended particles. The high amount of metals removed, 80% of the Cu and 30–60% of the Zn concentration, was probably withdrawn bound to the particle fraction. The highest removal of metal ions was obtained in the sulphide mine leachate with Carex peat, removing 97–99% of the Zn and 85–100% of the Cu content. The Sphagnum peat sample removed 37–77% of the Zn and 80–100% of the Cu content. The differences found between Sphagnum and Carex peat were attributed to the original chemistry of the plant material and the habitat conditions at the time of peat formation. Generally, the combination of glauconite or clinoptilolite with the peat samples in column experiments gave a minor improvement in metal removal. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Sphagnum Peat, Carex Peat, Wastewater, Heavy Metals, Adsorption

Notes: highly cited

Benguella, B. and Benaissa, H. (2002), Cadmium removal from aqueous solutions by chitin: Kinetic and equilibrium studies. Water Research, 36 (10), 2463-2474.

Full Text: W\Wat Res36, 2463.pdf

Abstract: A fundamental investigation on the removal of cadmium ions from aqueous solutions by chitin was conducted in batch conditions. Kinetic data and equilibrium removal isotherms were measured. The influence of different experimental parameters such as time contact, initial concentration of cadmium, chitin mass, particles size, agitation speed, temperature and the nature of cadmium salt, on the kinetics of cadmium removal was studied. The main parameters that play an important part in removal phenomenon were initial cadmium concentration, particle size and chitin mass. Other parameters such as agitation speed, temperature and the nature of cadmium salt, showed a restricted effect on the removal kinetics. The process follows a pseudo second-order kinetics. The cadmium uptake of chitin was quantitatively evaluated using sorption isotherms. In order to describe the isotherm mathematically, the experimental data of the removal equilibrium were correlated by either the Langmuir or Freundlich equations. Results indicated that the Langmuir model gave a better fit to the experimental data than the Freundlich equation. Scanning electron microscopy coupled with a X-ray energy dispersed analysis for cadmium-equilibrated chitin, demonstrated that cadmium-containing nodules existed on the surface chitin. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Removal, Kinetic, Equilibrium, Cadmium, Chitin, Wastewater Treatment, Rhizopus-arrhizus, Heavy-Metals, Saccharomyces-Cerevisiae, Biosorption, Adsorption, Sorption, Uranium, Mechanism, Lead, Accumulation

Gupta, V.K., Jain, C.K., Ali, I., Chandra, S. and Agarwal, S. (2002), Removal of lindane and malathion from wastewater using bagasse fly ash: A sugar industry waste. Water Research, 36 (10), 2483-2490.

Full Text: W\Wat Res36, 2483.pdf

Abstract: The bagasse fly ash, obtained from the local sugar industry, has been used as inexpensive and effective adsorbent for the removal of lindane and malathion from wastewater. The optimum contact needed to reach equilibrium was found to be 60 min. Maximum removal takes place at pH 6.0. The removal of the pesticides increases with an increase in adsorbent dose and decreases with adsorbent particle size. The optimum adsorbent dose is 5 g/l of particle size 200-250 pm. Removal of the two pesticides was achieved up to 97-98% under optimum conditions. The material exhibits good adsorption capacity and follows both Langmuir and Freundlich models. Thermodynamic parameters also indicate the feasibility of the process. The adsorption was found to be exothermic in nature. At lower concentrations, adsorption is controlled by film diffusion, while at higher concentrations, it is controlled by particle diffusion mechanisms. The adsorbent is a very useful and economic product for the removal of lindane and malathion. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Adsorption, Removal, Wastewater, Bagasse Fly Ash, Lindane, Malathion, Chromatography Mass-Spectrometry, Gas-Chromatography, Aqueous-Solutions, Red Mud, Water, Pesticides, Cadmium, Copper, Lead, Slag

Notes: highly cited

? Laspidou, C.S. and Rittmann, B.E. (2002), A unified theory for extracellular polymeric substances, soluble microbial products, and active and inert biomass. Water Research, 36 (11), 2711-2720.

Full Text: 2002\Wat Res36, 2711.pdf

Abstract: We present a critical review of the relationships among three microbial products: extracellular polymeric substances (EPS), soluble microbial products (SMP), and inert biomass. Up to now, two different “schools” of researchers have treated these products separately. The “EPS school” has considered active biomass and EPS, while the “SMP school” has considered active biomass, SMP, and inert biomass. Here, we provide a critical review of each of the microbial products. Then, we develop a unified theory that couples them and reconciles apparent contradictions. In our unified theory, cells use electrons from the electron-donor substrate to build active biomass, and they also produce bound EPS and utilization-associated products (UAP) at the same time and in proportion to substrate utilization. Bound EPS are hydrolyzed to biomass-associated products (BAP), while active biomass undergoes endogenous decay to form residual dead cells. Finally, UAP and BAP, being biodegradable, are utilized by active biomass as recycled electron-donors substrates. Our unified theory shows that the apparently distinct products from the SNIP and EPS schools overlap each other. Soluble EPS is actually SMP, or the sum of UAP and BAR Furthermore, active biomass, as defined by the SNIP school, includes bound EPS, while inert biomass includes bound EPS and the residual dead cells. (C) 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Biofilm, Extracellular Polymeric Substances (EPS), Hydrolysis, Inert Biomass, Soluble Microbial Products (SMP), Pseudomonas-Aeruginosa, Exopolysaccharide Production, Continuous-Culture, Biofilms, Kinetics, Sludge, Model, Polysaccharides, Nitrification, Biosynthesis

Inglezakis, V.J. Loizidou, M.D. and Grigoropoulou, H.P. (2002), Equilibrium and kinetic ion exchange studies of Pb²⁺, Cr³⁺, Fe³⁺ and Cu²⁺ on natural clinoptilolite. Water Research, 36 (11), 2784-2792.

Full Text: W\Wat Res36, 2784.pdf

Abstract: In the present study ion exchange of Pb²⁺, Cu²⁺, Fe³⁺ and Cr³⁺ on natural clinoptilolite is examined at 27±1°C and initial concentration of 10 meq/dm³. Equilibrium is favorable for Pb²⁺, unfavorable for Cu²⁺ and sigmoid for Cr³⁺ and Fe³⁺. Selectivity series deduced from equilibrium isotherms is Pb²⁺ > Cr³⁺ > Fe³⁺ > Cu²⁺, while when maximum exchange levels (MELs) are considered, selectivity series is Pb²⁺ > Cr³⁺  Cu²⁺  Fe³⁺. Cu²⁺ manifests the higher value of diffusion coefficient in the clinoptilolite particles among the metals studied, equal to 1.40×10^-9 cm²/s. According to the fixed bed experiments the upflow rate (5–15 Bed Volumes (BV)) is influencing the breakthrough point for all metals studied. The breakthrough point varies between 12.3 BV for Pb²⁺ and 1.18 for Cu²⁺. Flow rate is also influencing the operating capacity, giving values between 0.433 meq/g_{clinoptilolite} for Pb²⁺ and 0.053 for Fe³⁺. Breakthrough point values confirm the selectivity order deduced from the equilibrium isotherms, while operating capacity values confirm the selectivity order deduced from MEL experiments.

Keywords: Clinoptilolite, Heavy Metals, Ion Exchange, Fixed Beds

Robinson, T., Chandran, B. and Nigam, P. (2002), Removal of dyes from a synthetic textile dye effluent by biosorption on apple pomace and wheat straw. Water Research, 36 (11), 2824-2830.

Full Text: W\Wat Res36, 2824.pdf

Abstract: This paper deals with two low-cost, locally available, renewable biosorbents; apple pomace and wheat straw for textile dye removal. Experiments at total dye concentrations of 10, 20, 30, 40, 50, 100, 150, and 200 mg/l were carried out with a synthetic effluent consisting of an equal mixture of five textile dyes. The effect of initial dye concentration, biosorbent particle size, quantity of biosorbent, effective adsorbance, dye removal and the applicability of the Langmuir and Freundlich isotherms were examined. One gram apple pomace was found to be a better biosorbent, removing 81% of dyes from the synthetic effluent at a particle size of 2mm×4mm and 91% at 600 μm. Adsorption of dyes by apple pomace occurred at a faster rate in comparison to wheat straw. Both the isotherms were found to be applicable in the case of dye adsorption using apple pomace.

Keywords: Adsorption, Apple Pomace, Dye Removal, Textile Dyes, Wheat Straw

Chegrouche, S. and Bensmaili, A. (2002), Removal of Ga(III) from aqueous solution by adsorption on activated bentonite using a factorial design. Water Research,