Personal Research Database

Full Text: W\Wat Res32, 3601.pdf

Abstract: Removal of PCNB from aqueous solutions by fungal mycelia was studied. Adsorption of the fungicide by dead biomass of M. racemosus, R. arrhizus and S. cyanescens was determined and compared with sorption on isolated cell walls of these three strains. Biosorptive uptake capacities are described by Freundlich equations of the form Q_e = K_f. C_e (nr). Measured values of K_f and n (f) indicate significant differences in the curve shapes and sorption capacities between the three species. Better performances were revealed by M. racemosus and R. arrhizus. Sorption of PCNB by cell walls alone was lower and statistically different from sorption by heat-killed mycelia thus corroborating that biosorption involved both uptake by the cell walls and by other cellular components.

Keywords: Hazardous Organic Pollutants, Rhizopus-arrhizus Biomass, Saccharomyces-Cerevisiae, Microbial Biomass, Cell-Walls, Metal-Ions, Biosorption, Accumulation, Mechanism, Microorganisms, Biosorption, PCNB, Fungi, Mucor racemosus, Rhizopus arrhizus, Sporothrix Cyanescens

Notes: highly cited

Raji, C. and Anirudhan, T.S. (1998), Batch Cr(VI) removal by polyacrylamide-grafted sawdust: Kinetics and thermodynamics. Water Research, 32 (12), 3772-3780.

Full Text: W\Wat Res32, 3772.pdf

Abstract: Batch sorption studies have been carried out to determine the effect of adsorbent dose, initial sorbate concentration and pH on the adsorption of Cr(VI) on polymer-grafted sawdust. The process was found to be pH, temperature and concentration dependent. An empirical relationship has been obtained to predict the percentage Cr(VI) removal at any time for known values of sorbent and initial sorbate concentration under observed test conditions. The effect of diverse ions has been studied and it is found that there is very little effect on the sorption of Cr(VI). The process was found to be exothermic with a maximum adsorption of 91.0% at 30°C for an initial concentration of 100 mg l^-1 at pH 3. The process follows first-order kinetics and the data fits the Freundlich adsorption isotherm. Thermodynamic parameters were also evaluated. Desorption studies confirmed that adsorbent can be effectively regenerated using 0.2 M NaOH and 0.5 M NaCl and can then be reused. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Sawdust, Chromium Adsorption, Adsorption Isotherm, Regeneration, Aqueous-Solutions, Activated Carbon, Adsorption, Chromium

Maynard, H.E., Ouki, S.K. and Williams, S.C. (1999), Tertiary lagoons: A review of removal mechanisms and performance. Water Research, 33 (1), 1-13.

Full Text: W\Wat Res33, 1.pdf

Abstract: Tertiary lagoons, or maturation ponds, have generally been viewed as an effective and low-cost method of removing pathogens from wastewater. Their low operation and maintenance costs have made them a popular choice for wastewater treatment, particularly in developing countries since there is little need for specialised skills to run the systems. This paper provides a critical review of the literature on the removal mechanisms operating in tertiary lagoons, and their overall performance. Numerous physical and chemical parameters have been suggested as factors involved in bacterial removal, and particular attention is paid in this paper to the relationship between pH, dissolved oxygen concentration and light. Very little information is available on the mechanisms of removal for intestinal parasites or viruses, or for BOD, COD or heavy metals. The two proposed mechanisms for nitrogen removal (ammonia volatilisation and sedimentation of organic nitrogen) are discussed. It has become obvious from the wide variations in performance reported in the literature that the design criteria currently in use for lagoons are not adequate. It is thought that by gaining a better understanding of the removal mechanisms operating in the lagoons, the design of new lagoons can be improved. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Tertiary Lagoons, Maturation Ponds, Removal Mechanisms, Performance, Waste Stabilization Ponds, Nematode Egg Removal, NEAR-UV Radiation, Bacterial Die-Off, Giardia Sp Cysts, Escherichia-Coli, Vibrio-Cholerae, Northeast Brazil, Fecal-Coliforms, Water Treatment

Ning, Z., Fernandes, L. and Kennedy, K.J. (1999), Chlorophenol sorption to anaerobic granules under dynamic conditions. Water Research, 33 (1), 180-188.

Full Text: W\Wat Res33, 180.pdf

Abstract: This study examined the nonideal sorption phenomena and the effect of mixing conditions on sorption of five chlorophenols (CPs) onto anaerobic granules (AG) under dynamic conditions in continuous bioreactors. Under dynamic bioreactor conditions, anaerobic sorption of CPs which follow sorption linearity and sorption-desorption singularity, can be described by a dynamic model incorporating linear sorption. Nonequilibrium sorption caused by diffusion limitations in anaerobic reactors was found to be negligible, which is a result of the strong hydrodynamic dispersion that prevails in anaerobic reactors and the high porosity of AG. However, minor nonideal sorption phenomena were observed for 3, 4-dichlorophenol and pentachlorophenol, both of which showed sorption-desorption isotherm hysteresis. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Anaerobic, Granules, Sorption, Chlorophenols, Bioreactor, Dynamic, Toxic Organic-Compounds, Waste-Water Solids, Nonequilibrium Sorption, Soil Columns, Transport, Sludge, Pentachlorophenol, Biosorption, Pollutants, Effluent

? Glass, C. and Silverstein, J. (1999), Denitrification of high-nitrate, high-salinity wastewater. Water Research, 33 (1), 223-229.

Full Text: 1999\Wat Res33, 223.pdf

Abstract: Denitrification of a wastewater containing 36,000 mg/L NO₃- (8,200 mg/L NO₃-N) with ionic strength of 3.0 has been achieved using activated sludge in bench-scale sequencing batch reactors. An activated sludge culture was acclimated to denitrify the wastewater at pH 9, by step-wise increase in wastewater nitrate concentration from 2,700 mg/L NO₃-N to 5,400 mg/L NO₃-N and finally to 8,200 mg/L NO₃-N. Simultaneously, wastewater ionic strength was increased from 0.8 to 2.7 and to 3.0 (5, 16, and 18% total dissolved solids (TDSI). Although complete denitrification occurred, the maximum specific nitrate reduction rate decreased from 50 to 19 mg NO₃-N/g MLSS/h as wastewater nitrate and TDS concentration increased. Also, accumulation of nitrite increased and the maximum nitrite reduction rate decreased. A similar attempt to acclimate activated sludge to denitrify the high-TDS, high-nitrate wastewater at pH 7.5 was unsuccessful. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Denitrification, High Salinity Wastewater, Industrial Wastewater Treatment, Activated Sludge Acclimation, Sequencing Batch Reactor, Salt Concentrations, Water, Nitrite, Removal

Gebara, F. (1999), Activated sludge biofilm wastewater treatment system. Water Research, 33 (1), 230-238.

Full Text: W\Wat Res33, 230.pdf

Abstract: Plastic nets were fitted vertically inside the aeration tank of a conventional activated sludge process in a laboratory scale model. The aeration tank thus became a hybrid growth reactor combining both suspended and fixed biomass. The addition of nets resulted in considerable improvements in BOD₅ removal efficiency and sludge settling efficiency for a synthetic wastewater. Theoretical mathematical models predicting the performance of the hybrid growth reactor were proposed and their accuracy was affirmed by comparison with the experimentally measured results. The process has been termed Activated Sludge Biofilm Wastewater Treatment System (ASBWTS). Existing plants can be upgraded by the fitting of plastic nets in the aeration tank and new systems can be constructed at a reduced cost if plastic nets are used. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Wastewater Treatment, Activated Sludge, Hybrid Reactor, Upgrading, Biofilm Cultivation

Notes: highly cited

Matheickal, J.T., Yu, Q.M. and Woodburn, G.M. (1999), Biosorption of cadmium(II) from aqueous solutions by pre-treated biomass of marine alga Durvillaea potatorum. Water Research, 33 (2), 335-342.

Full Text: W\Wat Res33, 335.pdf

Abstract: Cadmium(II) adsorption properties of pre-treated biomass (PTB) of marine alga Durvillaea potatorum were investigated. Pre-treatment of the native biomass with calcium chloride and subsequent thermal treatment considerably improved the swelling properties and physical stability of the biomass granules. Batch and column experiments were conducted to determine the adsorption properties of the modified biomass. The adsorption capacity of the biomass strongly depends on equilibrium solution pH. At solution pH of 5, the maximum adsorption capacity of the pre-treated biomass is 1.1 mmol/g. The kinetics of cadmium adsorption was fast with 90% of adsorption taking place within 30 min. The feasibility of using pre-treated biomass granules in a packed bed was also examined. This study demonstrated that the pre-treated biomass of D. potatorum can be used as an efficient biosorbent for the treatment of cadmium bearing waste streams.

Keywords: Heavy-Metal Biosorption, Alginate Gel Beads, Rhizopus-arrhizus, Removal, Adsorption, Ions, Lead, Water, Microalgae, Gelation, Biosorption, Cadmium Removal, Durvillaea potatorum, Heavy Metal, Waste Water Treatment

Knapp, J.S. and Newby, P.S. (1999), The decolourisation of a chemical industry effluent by white rot fungi. Water Research, 33 (2), 575-577.

Full Text: W\Wat Res33, 575.pdf

Abstract: A wide range of strains of white rot fungi have been shown to be effective in the decolourisation of a chemical industry effluent containing a diazo-linked chromophore. The five most effective strains were selected for further study, all could give ca. 70–80% decolourisation. of these the best were strains of Coriolus versicolor. All five strains could decolourise the effluent at 5–40% v/v in nitrogen-limited medium. The greatest % decolourisation occurred at low effluent concentration but the initial rate and final extent of decolorisation was greatest at 40% v/v. At best, colour reductions of 119 and 147 absorbance units (at λ_max) were achieved in 3 and 7days, respectively. The presence of added manganese ions did not affect decolourisation although it did stimulate production of a red side product by some fungi. These results demonstrate the potential of white rot fungi in the treatment of chemical industry wastes. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: White Rot Fungi, Coloured Effluents, Chemical Effluents, Decolourisation, Coriolus Versicolor

Notes: highly cited

Ho, Y.S. and McKay, G. (1999), The sorption of lead(II) ions on peat. Water Research, 33 (2), 578-584.

Full Text: W\Wat Res33, 578.pdf

Abstract: The sorption of lead ions from aqueous solution onto peat has been studied. Kinetic studies have been carried out using an agitated batch and the effect of varying process parameters has been investigated; these include initial lead ion concentration, peat particle size, solution temperature and agitation speed. The data were analyzed using a pseudo-first order Lagergren equation and the data were correlated using a two-step first order reaction mechanism.

Keywords: Adsorption, Agitation, Aqueous Solution, First, First Order, Kinetic, Kinetics, Lagergren Equation, Lead, Lead(II), Mechanism, Particle Size, Peat, Pseudo-First Order, Pseudo-First-Order, Removal, Rights, Size, Solution, Sorption, Temperature

? Poeton, T.S., Stensel, H.D. and Strand, S.E. (1999), Biodegradation of polyaromatic hydrocarbons by marine bacteria: Effect of solid phase on degradation kinetics. Water Research, 33 (3), 868-880.

Full Text: 1999\Wat Res33, 868.pdf

Abstract: Biodegradation kinetics for phenanthrene and fluoranthene, as a function of their dissolved concentrations, were determined for a marine PAH-degrading enrichment. Biodegradation rates in the presence of artificial (Celite coated with humic acid) or Puget Sound sediments with sorbed PAH were then determined. These rates were expected to be slower than for the tests without sediment, because of limited PAH in the soluble phase due to desorption limitations of PAH from the solid to liquid phases. Due to the low aqueous PAH concentrations that exist for PAH compounds, radiolabeled PAH compounds were used to follow the fate of the PAH compounds in batch degradation test. The radiolabeled compounds were followed as evolved CO2, unreacted PAH in the dissolved phase or sorbed to sediment, and as non-polar intermediate products. Epifluorescence microscopy was used to determine if the marine enrichment bacteria could attach to sediment during PAH degradation. Without sediment, first-order degradation rate coefficients with respect to PAH concentration for phenanthrene ranged from 0.033 to 0.139 L/mg-d. depending on when the marine enrichment was tested, Fluoranthene first-order degradation rate coefficients without sediment were 0.132 and 0.162 L/mg-d. With sediment present, degradation rates for phenanthrene rind fluoranthene were 2.1 to 3.5 and 2.1 to 5.3 times faster, respectively, than the degradation rates at the same aqueous PAH and biomass concentrations without sediment, With phenanthrene present about 50% of the biomass added to test samples was attached to the sediment. The results suggest that biomass interactions with sorbed PAH at the sediment particle surfaces account for increased PAH degradation rates in the presence of a solid phase material. (C) 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Phenanthrene, Fluoranthene, Marine Bacteria, Biodegradation Kinetics, Aerobic, Sediment, Sorption, Radiolabeled Carbon, Polyaromatic Hydrocarbons, Phenanthrene, Bioavailability, Surfactants, Attachment, Growth, Water

Morais, L.C., Freitas, O.M., Gonçalves, E.P., Vasconcelos, L.T. and González Beça, C.G. (1999), Reactive dyes removal from wastewaters by adsorption on eucalyptus bark: Variables that define the process. Water Research, 33 (4), 979-988.

Full Text: W\Wat Res33, 979.pdf

Abstract: An attempt to help solving the pollution problem caused by the presence of reactive dyes in textile effluents, was undertaken. Owing to the fact that eucalyptus bark is a very abundant, inexpensive, forest residue in the authors’ country, Portugal, it was decided to experiment with it as a potential adsorbent for a certain type of the supracited pollutants used in cellulose fibers dyeing (Remazol BB). In order to study the variables that define the process, 24 and 25 factorial experimentations were carried out, in two stages. In the first one, the variables selected were: temperature, initial pH, sodium chloride concentration and initial dye concentration/bark concentration ratio. As tests showed that the last parameter did not describe the adsorption process, another stage followed, keeping the first three variables and substituting initial dye concentration and bark concentration separately for their ratio. It was verified that all the variables studied had significant influence on the adsorption process at the level of 1% probability. The influence order was: initial dye concentration > bark concentration > initial pH > sodium chloride concentration > temperature. Parallel adsorption tests, under similar conditions, carried out with a commercial activated carbon and with eucalyptus bark, showed for the last one an adsorption capacity about half of that of the first one. It is considered that the obtained results are quite encouraging, though there is still a long way to go before definitive conclusions may be withdrawn.

Keywords: Activated Carbon, Adsorption, Adsorption Capacity, Capacity, Eucalyptus Bark Adsorbent, Experiment, Peat, Pollutants, Pollution, Process, Reactive Dyes, Reactive Dyes Removal, Stages, Temperature, Waste-Waters

Hijnen, W.A.M., Jong, R. and Van der Kooij, D. (1999), Bromate removal in a denitrifying bioreactor used in water treatment. Water Research, 33 (4), 1049-1053.

Full Text: W\Wat Res33, 1049.pdf

Abstract: Bromate (BrO₃^-), an anion with carcinogenic properties, may be present in drinking water when bromide-containing water is ozonated during treatment or when it is present in surface water used as the source. Experiments showed that the concentration of BrO₃^- was reduced in a denitrifying bioreactor supplemented with ethanol, when NO₃^- was almost completely removed. At BrO₃^- concentrations of 25 and 35 µg/l and a temperature of 12°C the removal rates were 0.6 and 0.8 pg l^-1 min^-1, respectively. Calculations based on bromate concentration profiles in the bioreactor revealed that contact times of 25-50 min will be necessary to obtain concentrations below 3 µg/l, the 10^-5 cancer risk level. Furthermore, intensive post treatment of the filtrate is required to remove biomass and excess ethanol applied for complete denitrification. Therefore, bromate removal in a denitrifying bioreactor does not seem to be a realistic option in drinking water treatment. Soil passage under anoxic conditions as occurring during artificial recharge or river bank filtration may enable BrO₃^--removal from (ozonated) surface water. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Drinking Water, Ozonation, Bromate Reduction, Denitrifying Bioreactor, Ozonation, Bromide

Pelekani, C. and Snoeyink, V.L. (1999), Competitive adsorption in natural water: Role of activated carbon pore size. Water Research, 33 (5), 1209-1219.

Full Text: W\Wat Res33, 1209.pdf

Abstract: The impact of pore size on the competition mechanism between natural organic matter (NOM) in Illinois groundwater and the micropollutant atrazine was assessed using activated carbon fibers (ACFs). Two microporous ACFs with narrow and broad pore size distributions, designated ACF-10 and ACF-25, respectively, were used. The average pore sizes of ACF-10 and ACF-25 were 6 and 13.4 Angstrom. Single solute adsorption, simultaneous adsorption and preloading experiments were performed. On ACF-10 it was found that the adsorption of atrazine was reduced significantly in the presence of NOM, even though the NOM loading was very small as a result of pore exclusion. The uptake of atrazine by ACF-10 in the presence of NOM (simultaneous adsorption) was comparable to the NOM-preloaded capacity. In addition, preloaded atrazine was not displaced by subsequently adsorbed NOM. The results support a pore blockage mechanism by which NOM molecules block access to, but do not penetrate into the primary micropores. Atrazine capacity on ACF-25 which has primary micropores as well as a large volume of secondary micropores, was reduced in the presence of NOM; however, the reduction in capacity was much less than that observed with ACF-10. Preloading with NOM showed further capacity reduction compared with simultaneous adsorption. These results combined with the result that preloaded atrazine exposed to NOM showed displacement of atrazine support a direct site competition mechanism in the secondary micropore region. Attempts to regenerate NOM preloaded ACF-10 and ACF-25 using a strong alkali solution failed to recover atrazine capacity, suggesting that NOM was strongly adsorbed at the fiber surface as well as within micropores. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: ACF, Pore Size Distribution, Competition Mechanism, Pore Blockage, Atrazine, Nom, Humic Substances, Organic-Compounds, Fibers, Adsorbents

Mameri, N., Boudries, N, Addour, L., Belhocine, D., Lounici, H., Grib, H. and Pauss, A. (1999), Batch zinc biosorption by a bacterial nonliving Streptomyces rimosus biomass. Water Research, 33 (6), 1347-1354.

Full Text: W\Wat Res33, 1347.pdf

Abstract: The zinc biosorption capacity of a Streptomyces rimosus biomass was studied in the batch mode. After a heat pretreatment, optimum conditions of biosorption were found to be: an average saturation contact time of 4 h, a biomass particle size between 140 and 250 µm, the ambient temperature, a stirring speed of 250 rpm, and pH of 7.5. The equilibrium data could be fitted by a Langmuir isotherm equation. Under these optimal conditions, up to 30 mg (Zn)/g (biomass), was fixed. Moreover, additional chemical treatment of the biomass by NaOH (1 mol/L), increased the biosorption Capacity of about 80 mg (Zn)/g (biomass).

Keywords: Uranium Biosorption, Metal Biosorption, Rhizopus-arrhizus, Copper Adsorption, Mucor-Miehei, Heavy-Metals, pH, Removal, Strain, Cells, Zinc, Streptomyces Rimosus, Biosorption, Heavy Metals

Zhao, M., Duncan, J.R. and van Hille, R.P. (1999), Removal and recovery of zinc from solution and electroplating effluent using Azolla filiculoides. Water Research, 33 (6), 1516-1522.

Full Text: W\Wat Res33, 1516.pdf

Abstract: The removal of zinc ions from aqueous solutions and electroplating rinse effluent by Azolla filiculoides on batch and column studies was investigated. The maximum zinc uptake by Azolla in batch systems at an optimum pH of 6.0 was found to be 45.2 mg/g, The dried Azolla filiculoides showed good mechanical stability and flow-permeability in repeated column operations. The zinc uptake in column operation at pH 6.2 and 60% breakthrough was between 25.8-30.4 mg/g with varying Row rates (from 32 to 160 ml/h.g). Complete desorption of bound zinc was accomplished with 120 mi of either 0.2 N H₂SO₄ or HCl. The data from regeneration efficiencies for six cycles, evidenced that the reusability of Azolla in the treatment of Zn²⁺-laden wastewater is viable. An effluent-free, closed loops of zinc treatment system, with Azolla biomass as the sorbent, is proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Azolla Filiculoides, Zn²⁺, Heavy Metals, Column Sorprion, Desorption, Recovery, Regeneration, Heavy-Metal, Biomass, Biosorption, Regeneration, Yeast

Yu, Q.M., Matheickal, J.T., Yin, P.H. and Kaewsarn, P. (1999), Heavy metal uptake capacities of common marine macro algal biomass. Water Research, 33 (6), 1534-1537.

Full Text: W\Wat Res33, 1534.pdf

Abstract: Biosorption of heavy metals is an effective technology for the treatment of industrial waste waters. The uptake capacities of the biomass of a group of nine marine macro algae for heavy metal ions (cadmium, copper and lead) were evaluated. Equilibrium isotherms for each biomass-heavy metalsystem were obtained from batch adsorption experiments. The maximum uptake capacities of the biomass ranged from around 0.8 to 1.6 mmol/g (dry), which were much higher than those of other types of biomass. The results indicated that the biomass of the marine algae is suitable for the development of efficient biosorbents for the removal and recovery of heavy metals from waste water.

Keywords: Saccharomyces-Cerevisiae, Aqueous-Solutions, Adsorption-Isotherms, Cadmium Biosorption, Rhizopus-arrhizus, Radiata, Lead(II), Removal, Uranium, Cu(II), Biosorption, Heavy Metal Removal, Marine Algae, Waste Water Treatment

Walker, G.M. and Weatherley, L.R. (1999), Kinetics of acid dye adsorption on GAC. Water Research, 33 (8), 1895-1899.

Full Text: W\Wat Res33, 1895.pdf

Abstract: This work involves the treatment of simulated industrial waste water containing acid dyestuffs with granular activated carbon adsorption selected as the treatment method. Predicting the rate at which adsorption takes place for a given system is probably the single most important factor for adsorber design, with adsorbate residence time and ultimately the reactor dimensions controlled by the system’s kinetics. A fixed volume stirred tank reactor was used to study the kinetics of adsorption in a single component system. Process parameters including the rate of agitation, dye concentration and phase ratio were studied with results being modelled using a dual resistance external mass transfer and solid diffusivity model. A single value of solid diffusivity described the adsorption decay curves in most instances and also indicated that chemisorption is the likely process of acid dye adsorption onto activated carbon.

Keywords: Adsorption, Activated Carbon, Dyes, Solid Diffusion, External Mass Transfer, Stirred Tank Reactor

Zhou, P., Huang, J.C., Li, A.W.F. and Wei, S. (1998), Heavy metal removal from wastewater in fluidized bed reactor. Water Research,