Personal Research Database

Full Text: W\Wat Sci Tec34, 155.pdf

Abstract: The best prospects for successful wetland treatment should be in the warmer regions of the world, but studies in North America and Scandinavia show that wetland treatment may be feasible also in cooler regions. A review shows that the number of wetlands of different types (free water surface, FWS; horizontal and vertical subsurface flow, SSF), treating different kinds of wastewater, is steadily increasing in most parts of the cold temperate regions of the world. The major wetland engineering concerns in cold climates, which are discussed in this paper, are related to: (1) ice formation, and its implications for hydraulic performance; (2) hydrology and hydraulic issues besides ice formation; and (3) the thermal consequences for biologically or microbiologically mediated treatment processes. Energy-and water-balance calculations, as well as thermal modeling, are useful tools for successful design and operation of treatment wetlands, but the shortage of data makes it necessary to adopt a conservative approach. The treatment processes often appear less temperature sensitive in full-scale wetlands as compared to laboratory incubations. Several possible explanations are discussed in the paper: (1) sedimentation playing a significant role, (2) overdimensioning in relation to some constituents, (3) seasonal adsorption (cation exchange) of ammonium, and (4) temperature adaptation of the microbial community. Experience shows that cold climate wetlands can meet effluent criteria for the most important treatment parameters. To gain wide acceptance, however, we need to become more specific about design and construction, and also about operation, maintenance and cost-effectiveness. These goals require detailed knowledge about processes in full-scale wetlands, including long-term changes and response to maintenance.

Keywords: Nutrient Removal, Water, Cold Climate, Design, Geographical Distribution, Hydrology, Operation, Plant Uptake, Purification Processes, Nutrient Removal, Treatment Wetlands, Treatment Performance, Wastewater

Suzuki, M. (1997), Role of adsorption in water environment processes. Water Science and Technology, 35 (7), 1-11.

Full Text: W\Wat Sci Tec35, 1.pdf

Abstract: Aqueous phase adsorption isotherms and adsorption rates are reviewed. Among numbers of isotherm equations, A. combination of adsorption potential and solvophobic concept was applicable to interpreting adsorption equilibrium data obtained for agrochemicals on activated carbon fiber. Intraparticle diffusion becomes the rate-limiting step in liquid phase adsorption on granular activated carbons. Correlation of diffusion coefficients based on surface diffusion mechanisms is introduced. As topics related to adsorption, sediment water partition, biological activated carbon, removal of volatile organics and nutrient removal are briefly reviewed. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Activated Carbon-Fibers, Aqueous-Solutions, Coefficient, Adsorption Equilibrium, Adsorption Potential, Adsorption Rate, Biological Activated Carbon, Drinking Water, Nutrient Removal, Regeneration, Surface Diffusion

Yoshida, H. and Takemori, T. (1997), Adsorption of direct dye on cross-linked chitosan fiber: Breakthrough curve. Water Science and Technology, 35 (7), 29-37.

Full Text: W\Wat Sci Tec35, 29.pdf

Abstract: The recovery of direct dye by adsorption on cross-linked fiber (ChF-D), which we have developed, appeared technically feasible. The concentration of amino group fixed in the adsorbent phase was 3.30 mol/kg dry fiber. A typical direct dye, Brilliant Yellow (M.W. = 625, divalent anion) was used in this experimental study. The breakthrough curves for adsorption of the dye were measured for different flow rates, bed heights, influent concentrations of the dye, and temperatures. The experimental breakthrough curves showed that ChF-B recovered the dye efficiently even from the hot dye solution. Axial dispersion coefficient E-z (m²/s) in fibrous bed was measured and the following correlation for the dispersion coefficient was obtained: Ez = 5.4×10^-6 Re’ (1.1) (epsilon = 0.698) Ez = 4.7×10^-6 Re’ (1.2) (epsilon = 0.813) where epsilon denotes void fraction of the bed. The theoretical breakthrough curve obtained by considering the effect of axial dispersion was close to that obtained from the analytical solution for rectangular isotherm system without considereing the axial dispersion in Re’ > 0.46. The experimental breakthrough curves in pH less than or equal to 4 agreed well with the analytical solution. The intrafiber effective phase diffusivity of the dye at 323 K was about two times larger than that at 298 K and the bed capacity at 323 K was almost the same as that at 298 K.

Keywords: External Mass-Transfer, Pore Diffusion-Model, Activated Carbon, Batch Adsorbers, Acid Dye, Dyestuffs, Equilibria, Chitin, Peat, Adsorption, Chitosan Fiber, Direct Dye, Wastewater Treatment, Breakthrough Curve, Axial Dispersion, Fibrous Bed, Rectangular Isotherm

Hano, T., Takanashi, H., Hirata, M., Urano, K. and Eto, S. (1997), Removal of phosphorus from wastewater by activated alumina adsorbent. Water Science and Technology, 35 (7), 39-46.

Full Text: W\Wat Sci Tec35, 39.pdf

Abstract: The adsorption characteristics of activated alumina treated with aluminum sulfate were studied to develop a new removal process for low concentration phosphorus in the waters of rivers and lakes. The equilibrium study showed that the adsorption capacity was enhanced about 1.7-fold by treating with aluminum sulfate. The effective intraparticle diffusion coefficients, determined by the Boyd’s method based on batch runs, were hardly affected by such a low phosphorus concentration as observed in the water of rivers and lakes under investigation. The temperature dependence of the intraparticle diffusion coefficients based on the concentration in solid showed the activation energy of 29.7kJ.mol^-1, which was a little higher than that in usual pore diffusion. The maximum continuous operation term (regeneration cycle) of the present phosphorus adsorption system was estimated. Under the conditions of influent phosphorus concentration of 0.1g.m^-3, removal extent of 90%, particle size of 210^-3m, temperature of 298K and space velocity of 1.3910^-3s^-1 (5h^-1), the present removal system remained effective for about 500 days.

Keywords: Recovery, Water, Activated Alumina, Adsorption, Closed Water Area, Eutrophication, Phosphorus Removal

Weng, C.H., Wang, J.H. and Huang, C.P. (1997), Adsorption of Cr(VI) onto TiO₂ from dilute aqueous solutions. Water Science and Technology, 35 (7), 55-62.

Full Text: W\Wat Sci Tec35, 55.pdf

Abstract: Cr(VI) adsorption onto TiO₂ (anatase) particles was performed in batch equilibrium experiments. Results showed that pH was the key factor affecting the adsorption characteristics. The marked adsorption was observed under acidic condition and the adsorption capacities decreased with increasing pH, temperature, and ionic strength. The adsorption obeyed the Langmuir adsorption isotherm and the maximum adsorption capacities were determined at specific pH values. A surface complex formation model was proposed to describe the adsorption reaction between aqueous chromates and TiO₂ solid surface. Because the magnitude of electrostatic energy, the adverse solvation, and lateral interaction energy which contribute to the total adsorption are relatively small in comparison with the specific chemical energy, we conclude that the specific chemical interaction is the major mechanism responsible for the adsorption process. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Oxide-Water Interface, Ions, Adsorption, Cr(VI), Surface Complex Formation Model, TiO₂

? Lo, S.L., Jeng, H.T. and Lai, C.H. (1997), Characteristics and adsorption properties of iron-coated sand. Water Science and Technology, 35 (7), 63-70.

Full Text: 1997\Wat Sci Tec35, 63.pdf

Abstract: This study was conducted to develop a process for coating hydrated iron oxide on the surface of quartz sand to utilize the adsorbent properties of the coating and the filtration properties of the sand, Three coating parameters were investigated: pH, Fe concentration at which iron oxide was prepared, and the coating temperature. A Scanning Electron Microscope (SEM) and X-Ray Diffractometer (XRD) were used to observe the surface properties of the coated layer. Acid resistance was used to evaluate the attachment strength of the coated layer. Batch adsorption tests were performed to compare the effects of each coating parameter on the adsorption of heavy metals on the coated layer. Energy Dispersive Analysis of X-ray (EDAX) was used for characterizing metal adsorption sites on the iron-coated sand. The results indicated that the coated sand had more pores and higher specific surface area because of the attachment of iron oxide. The coated sand produced at higher pH((coating)) had better adsorption efficiencies of metals but had worse acid resistance. A high-temperature coating process enhanced the stability of the oxide coatings. Comparing heavy metal removal by adsorption on iron-coated sand and chemical precipitation, adsorption was shown to be capable of removing heavy metals over a wider pH range and to much lower levels than precipitation. The results from EDAX analysis showed that copper ions were chemisorbed on the surface of iron-coated sand. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Adsorption, Coatings, Goethite, Heavy Metal, Hematite, Hydrated Iron Oxide, Sand, Metal-Bearing Wastes

Tokunaga, S., Wasay, S.A. and Park, S.W. (1997), Removal of arsenic(V) ion from aqueous solutions by lanthanum compounds. Water Science and Technology, 35 (7), 71-78.

Full Text: W\Wat Sci Tec35, 71.pdf

Abstract: A new adsorption process for the removal of As(V) ion from aqueous solutions has been studied using lanthanum hydroxide (LH), lanthanum carbonate (LC) and basic lanthanum carbonate (BLC). These La compounds were effective in removing As ion to decrease the concentration down to < 0.001 mM. Dissolution of these La compounds was measured in the pH range of 2 to 12. The dissolution was appreciable at initial pH < 4.3, < 4.3 and < 4.0 for LH, LC and BLC, respectively. Kinetic study showed that the As removal was a first-order reaction in the neutral pH range and the rate constants were in the order of LH > LC > BLC. The As removal was highly pH-dependent. The optimum pH range was 3-8, 4-7 and 2-4 for LH, LC and BLC, respectively. The following two mechanisms are proposed: (i) adsorption by exchange of CO₃ and/or OH group with As ions in the neutral to alkaline pH range where La does not dissolve and (ii) precipitation of insoluble lanthanum arsenate, LaAsO₄, in the acid pH range. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Adsorption, Arsenic(V), Basic Lanthanum Carbonate, Dissolution, Kinetics, Lanthanum Carbonate, Lanthanum Hydroxide, Precipitation, Drinking-Water, Adsorption, Cerium

Fujie, K., Hu, H.Y., Lim, B.R. and Xia, H. (1997), Effect of biosorption on the damping of influent fluctuation in activated sludge aeration tanks. Water Science and Technology, 35 (7), 79-87.

Full Text: W\Wat Sci Tec35, 79.pdf

Abstract: To describe the organic removal performance in an activated sludge process, the effect of biological adsorption (biosorption, hereinafter) of both soluble and particulate organic substances (SOS and POS, respectively, hereinafter) on the rate of organic removal must be taken into account. This study quantitatively investigated the biosorption of organic pollutants in the domestic wastewater by tile activated sludge. The capability of biosorption and the rate of bio-oxidation of organic pollutants were formulated based on the experimental results as functions of both COD concentration and temperature. The biosorption capacity of activated sludge was proportional to COD concentration in the mixed liquor originated from the influent. The kinetic expressions were combined with the equation of longitudinal liquid mixing to set up the mathematical model to predict the effluent COD, and thus to clarify the effect of biosorption on the damping of influent fluctuations of both COD concentration and the inflow rate. The model was also successfully applied to assessing the effectiveness of MLSS control strategies in equalizing the effluent water quality.

Keywords: Wastewater Treatment, Activated Sludge Process, Biosorption, Bio-Oxidation, MLSS Control, Longitudinal Liquid Mixing, Mathematical Model Simulation, Damping of Influent Fluctuation, Aeration Tank

Baes, A.U., Okuda, T., Nishijima, W., Shoto, E. and Okada, M. (1997), Adsorption and ion exchange of some groundwater anion contaminants in an amine modified coconut coir. Water Science and Technology, 35 (7), 89-95.

Full Text: W\Wat Sci Tec35, 89.pdf

Abstract: The adsorption of nitrate, chromium (VI), arsenic (V) and selenium (VI) anions in an amine modified coconut coir (MCC-AE : with secondary and tertiary amine functionality) were studied to determine the capability of this easily prepared and low-cost material in removing typical groundwater anion contaminants.

Batch adsorption-ion exchange experiments were conducted using 200 mg MCC-AE, initially containing chloride as the resident anion, and 50 ml of different anion-containing water of varying concentrations. It is presumed, at this low pH, that only SeO₄^2- remained as a divalent anion, while monovalent species H₂AsO₄^- and HCrO₄^- predominated in their respective exchanging ion solutions. The adsorption data were fitted using the Freundlich equation and maximum adsorption fbr each anion was estimated using their respective Freundlich equation constants. MCC-AE exhibited preference for divalent Cr(VI) and Se(VI) anions compared with the Cl^- resident ion. Maximum As(V) adsorption was 0.086 mmol/g, while maximum adsorption of Cr(VI), NO₃^- and Se(VI) anions was 0.327 mmol/g, 0.459 mmol/g, and 0.222 mmol/g, respectively. The ion exchange capacity of MCC-AE is estimated, based on its exchange capacity for nitrate, to be within 0.46 mmol of positive charges per gram. Similar adsorption experiments were conducted for comparison using commercial chloride-form Amberlite IRA-900 strong base (quaternary amine functionality) anion exchanger, with an exchange capacity of 4.2 meq/g. Maximum adsorption of the different ions in IRA-900 was about 3 times higher for NO₃^-, 9 times higher for Se(VI), 10 times higher for As(V) and 9 times higher for Cr(VI), than that in MCC-AE. Differences in the ion exchange behavior of MCC-AE and IRA-900 were probably due to the different amine functionalities in the two exchangers. The results suggest that MCC-AE may be used as a low-cost alternative adsorbent/ion exchanger for treatment of anion contaminants in groundwater. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Adsorption, Anion Exchange, Arsenate, Chromate, Coconut Coir, Nitrate, Selenate

Sakoda, A., Sakai, Y., Hayakawa, K. and Suzuki, M. (1997), Adsorption of viruses in water environment onto solid surfaces. Water Science and Technology, 35 (7), 107-114.

Full Text: W\Wat Sci Tec35, 107.pdf

Abstract: Recently the contamination of water environment involving rivers, lakes, the sources of drinking water. etc. by viruses has been paid attention to as a new threat. The behavior of the viruses found in water environment is not well understood so far. However, it is suspected in general that the viruses are adsorbed onto solid surfaces such as suspended solids and sediment and keep their activities for a long time. Most likely, it is true that the adsorption of the viruses onto solid surfaces is one of the major factors controlling their transport and survival in water environment. In this work, the adsorption equilibrium relations of model viruses in water environment and their activities on solid surfaces were investigated. The E. coil phage such as Qss, fr, MS2 and T4 were employed for experiments as model viruses, and cellulose and its derivatives, kaolin, carbon black, etc. were chosen as model solid surfaces. All the adsorption isotherms of model viruses on model surfaces were successfully written as the linear expression by the Henry equation in the concentration range of 10²-10⁷ [PFU/ml]. The resultant Henry constants were correlated with the total acidity of the solid surfaces. Stability of the model viruses was completely different when they were adsorbed on the solid surfaces and when they were suspended in water. The viruses adsorbed on the solid surfaces were significantly stable compared with the suspended ones regardless of the surface properties. It is suggested that the shrinkage of the virus is one of the important survival factors and the adsorption onto solid surfaces enhances their activities. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Coliphage-Q-Beta, Waste-Water, Removal, Inactivation, Survival, Minerals, Biomass, Soils, Virus, E. Coli Phage, Adsorption, Desorption, Inactivation, Suspended Solid, Sediment

Chu, K.H., Hashim, M.A., Phang, S.M. and Samuel, V.B. (1997), Biosorption of cadmium by algal biomass: Adsorption and desorption characteristics. Water Science and Technology, 35 (7), 115-122.

Full Text: W\Wat Sci Tec35, 115.pdf

Abstract: The adsorption and desorption characteristics of a biosorption process comprising the biomass of the marine alga Sargassum baccularia, cadmium ions and desorbing agents hydrochloric acid and ethylenediaminetetraacetic acid (EDTA) were investigated using a batch reactor system. Both desorbents were effective in stripping adsorbed cadmium from the biomass. It was found that HCl at pH 2 could desorb 80% of the cadmium initially loaded onto the biomass. Almost complete recovery of cadmium was achieved by a 3.24 mM EDTA solution. The reusability of the biomass was tested in five consecutive adsorption-desorption cycles. The quantity of cadmium desorbed over the five cycles with either HCl or EDTA as desorbent corresponded well to the quantity loaded, indicating that complete desorption was readily achieved. However, the cadmium uptake capacity of the biomass deteriorated with repeated use of HCl or EDTA. HCl was found to have reduced cadmium uptake by 56% while the reduction for EDTA was nearly 40% over the five adsorption-desorption cycles. EDTA thus emerged as a slightly better desorbing agent compared with HCl. After completion of the five cycles it was found that 30% of the original biomass weight had been lost with HCl as the desorbent. EDTA exhibited desorption behaviour similar to that of HCl by causing a biomass loss of 16%. The loss of biomass indicates that some dissolution of biomass components containing cadmium binding sites apparently occurred, reducing the cadmium uptake capacity of the biomass in multiple cycles of adsorption-desorption.

Keywords: Marine-Algae, Biosorbent, Metals, Adsorption, Algae, Biosorption, Cadmium, Desorption, Heavy Metals, Seaweed, Wastewater

Lin, T.F. (1997), Diffusion and sorption of water vapor and benzene within a dry model soil organic matter. Water Science and Technology, 35 (7), 131-138.

Full Text: W\Wat Sci Tec35, 131.pdf

Abstract: The sorption behavior of water vapor and benzene within a dry model soil organic matter (SOM), peat, was studied. An electrobalance system was employed to determine both the equilibrium sorption isotherm and sorption-desorption kinetics. The sorption isotherm for water vapor was found to resemble that previously reported for this sample, while the sorption isotherm for benzene could not be determined, due to a failure to obtain reproducible sorption capacity. In the kinetic study, strong asymmetries between sorption and desorption rates were observed for both water vapor and benzene. Two diffusion models, accounting for either gas-phase pore diffusion within peat grains or solid-phase diffusion within microspheres of SOM, were used to interpret the asymmetric sorption rate data. Considering gas-phase pore diffusion only, the model resolved the asymmetry of sorption rates and described the experimental data very well for water vapor at three different concentrations. However, the pore diffusion model failed to capture the dominant feature of the experimental data for benzene. As a refinement, a model assuming that solid-phase intra-SOM diffusion is the rate-limiting mechanism produced a better description of the experimental data. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Sorption, Sorption Kinetics, Volatile Organic Compounds, Water Vapor, Soil Organic Matter, Feat, Long-Term Sorption, Aquifer Material, Natural Sediments, Partition, Peat, Resistance, Equilibria, Adsorption, Chemicals, Rates

Kameya, T., Hada, T. and Urano, K. (1997), Changes of adsorption capacity and pore distribution of biological activated carbon on advanced water treatment. Water Science and Technology, 35 (7), 155-162.

Full Text: W\Wat Sci Tec35, 155.pdf

Abstract: Several problems such as unpleasant odor, taste and toxic halogenated organic compounds which are produced by the reaction of organic substances with chlorine that is used for disinfection have occurred in water purification plant for drinking water. Advanced water treatment with biological activated carbon (BAG) has been focused on, but there are few papers about pore volume decrease of activated carbon in BAG. In this study, the changes in cumulative TOC removal and pore volume distribution for two types of activated carbon from a bench-scale apparatus and a mini-column apparatus, to which river water was supplied after coagulation-sedimentation for a period of over 1200 days, were investigated. Adsorption abilities decreased considerably after ca 1000 days and the activated carbons became like sand. The cumulative TOC removals by the adsorption effect were asymptotic to constant values for each empty bed contact time. Though the removal efficiencies for both the activated carbons were approximately equivalent, the pore volume decreases were not uniform. The volume of smaller pores under 2 nm in diameter mainly decreased. Accumulations of minerals such as aluminium and calcium were small, and the pore volume decreases were mainly caused by the accumulation of organic substances. Almost all of the organic substances that accumulated in the activated carbon could be extracted by sodium hydroxide solution. The mean density of the organic substances that accumulated in the activated carbon was estimated to be 0.91 g/ml. Since the pore volume decrease of the activated carbon was small compared with the removal amounts by the adsorption effect, A. large amount of organic substances that had adsorbed once disappeared and the pore volume of the activated carbon was regenerated. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: GAC, biological activated carbon, pore volume, pore distribution, advanced water treatment, drinking-water

Takeuchi, Y., Mochidzuki, K., Matsunobu, N., Kojima, R., Motohashi, H. and Yoshimoto, S. (1997), Removal of organic substances from water by ozone treatment followed by biological activated carbon treatment. Water Science and Technology, 35 (7), 171-178.

Full Text: W\Wat Sci Tec35, 171.pdf

Abstract: As an advanced water treatment, A. combination of ozonation and biological activated carbon (BAG, hereafter) treatment is being applied to purify raw water for municipal use in some cases. The authors examined effects of ozonation on water quality in a batch system, using water samples containing organic substances fractionated to several molecular weight ranges. Also, A. flow test of laboratory-scale was performed to study on the capability of the treatment in terms of removal efficiency of the dissolved organic substances, e.g., fumic substances, which preoxidized with ozone, As a result, the changes in equilibrium adsorption and in the biodegradability of organic substances dissolved in water before and after oxidation with ozone were made clear, (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Adsorption, Adsorption, Advanced Treatment, Biodegradation, Biological Activated Carbon, Drinking Water Purification, Fumic Substances, Molecular Weight Fractionation, Ozonation

Leyva-Ramos, R., Rangel-Mendez, J.R., Mendoza-Barron, J., Fuentes-Rubio, L. and Guerrero-Coronado, R.M. (1997), Adsorption of Cadmium(II) from aqueous solution onto activated carbon. Water Science and Technology,