Personal Research Database

Full Text: W\Wat Env Res69, 1032.pdf

Abstract: Adsorption-desorption of trichlorophenol (TCP) on calcium montmorillonite (pure clay), prepared montmorillonite-humic complexes. and natural soils were investigated. Adsorption followed a Freundlich-type isotherm between 5 and 30 mg/L of TCP, and linear adsorption isotherms were obtained for equilibrium concentrations up to 7 mg/L. Linear correlations were obtained between sorption constants (K-p) and organic carbon (f(oc)) and clay-mineral content (f(m)). In the montmorillonite and montmorillonite-humic complex systems, adsorption and desorption isotherms coincided and no hysteresis was observed. Strong hysteresis was observed in adsorption-desorption in natural soils. The different behavior in adsorption-desorption was explained by the different nature of organic matter, its different structure, and interaction with the mineral fraction. Because trichlorophenol is a weak acid, adsorption highly depended on pH and could be predicted by combining the adsorption constant of undissociated TCP and the dissociation constant of phenol-phenolate.

Keywords: Adsorption, Clay, Desorption, Organic Carbon, Remediation, Soil, Trichlorophenol, Organic-Chemicals, Natural Sediments, Aquifer Materials, Porous-Media, Sorption, Equilibrium, Pollutants, Matter

Grady, C.P.L., Magbanua, B.S., Brau, S. and Sanders, R.W. (1997), A simple technique for estimating the contribution of abiotic mechanisms to the removal of synthetic organic chemicals by completely mixed activated sludge. Water Environment Research, 69 (7), 1232-1237.

Full Text: W\Wat Env Res69, 1232.pdf

Abstract: Estimation of the contribution of abiotic removal mechanisms, such as volatilization and sorption, to the overall removal of a synthetic organic chemical (SOC) by the activated-sludge process is often necessary. Recognition that the only effect of the abiotic mechanisms is to reduce the concentration of biomass involved in the biodegradation of the SOC provides the means for estimating; that contribution. Knowledge of the fraction of the influent SOC concentration remaining in the effluent, the hydraulic and solids retention limes, the mixed liquor suspended solids concentration, the volatilization rate coefficient, and the sorption coefficient allows rapid computation of the fractional removal resulting from the abiotic mechanisms.

Keywords: Abiotic Removal, Activated Sludge, Sorption, Synthetic Organic Chemicals, Volatilization, Estimating Emissions, Surface Aeration, 20 VOCs

? Dutta, N.N., Borthakur, S. and Baruah, R. (1998), A novel process for recovery of phenol from alkaline wastewater: Laboratory study and predesign cost estimate. Water Environment Research, 70 (1), 4-9.

Full Text: 1998\Wat Env Res70, 4.pdf

Abstract: A novel process for recovery of phenol from alkaline wastewater has been demonstrated at laboratory scale. The process is based on the polymer-supported phase-transfer-catalyzed reaction of alkaline phenols with benzoyl chloride dissolved in toluene. The reaction conducted in a triphase system at room temperature generates phenyl benzoate, which is subsequently recovered as the product. Phosphonium ion immobilized on chloromethyl polystyrene crosslinked with divinylbenzene was used as the catalyst. Laboratory experiments were conducted in a batch slurry reactor and a fixed-bed reactor to assess the suitability of a particular reactor type to practical applications.

An aqueous phase to organic phase volume ratio of 1:2 was found to be suitable. The slurry reactor was found to be more attractive for the reaction. Based on the result of experiments in batch slurry reactors and other processing steps, a conceptual flow scheme was proposed for the process, and a predesign cost estimate was made. As such, the treatment cost of the proposed process is higher than that of the usual solvent extraction process, but the capital cost is comparable. However, the cost of the recovered phenyl benzoate will more than offset the higher treatment cost. This is reflected in a payback period of 1.5 years for the proposed process as compared to 2.5 years for the typical solvent extraction process. For industrial applications, a pilot-plant study needs to be performed for a detailed cost analysis.

Keywords: Phenol Recovery, Batch Slurry Reactions, Fixed-Bed Reactors, Absorption, Air Stripping, Membrane Separation, Costs, Dephenolization Scheme, Substances, Stream

Bulloch, J.L., Hand, D.W. and Crittenden, J.C. (1998), A model for predicting contaminant removal by adsorption within the international space station water processor: 1. Multicomponent equilibrium modeling. Water Environment Research, 70 (1), 14-26.

Full Text: W\Wat Env Res70, 14.pdf

Abstract: A thermodynamic model is developed to predict adsorption equilibrium in the International Space Station water processor’s multifiltration beds. The model predicts multicomponent adsorption equilibrium behavior using single-component isotherm parameters and fictitious components representing the background matrix. The fictitious components are determined by fitting total organic carbon and tracer isotherms with the ideal adsorbed solution theory. Multicomponent isotherms using a wastewater with high surfactant and organic compound concentrations are used to validate the equilibrium description on a coconut-shell-based granular activated carbon (GAG), coal-based GAG, and a polymeric adsorbent.

Keywords: Multi-Solute Adsorption, Thermodynamics, Multifiltration Bed, Multicomponent Adsorption, Isotherm, Equilibrium

Flanagan, W.P. (1998), Biodegradation of dichloromethane in a granular activated carbon fluidized bed reactor. Water Environment Research, 70 (1), 60-66.

Full Text: W\Wat Env Res70, 60.pdf

Abstract: A biological fluidized-bed reactor (FBR) containing biomass attached to granular activated carbon (GAG) was investigated for the treatment of aqueous-phase dichloromethane (DCM). The system was directly inoculated with fresh biomass solids collected from a General Electric Plastics wastewater treatment facility, located in Mount Vernon, Indiana. The biomass consumed DCM as its sole carbon and energy source following an acclimation period of approximately 8 days. Dichloromethane biodegradation rates in excess of 40 kg/m³d were achieved during continuous operation, with no detectable DCM (< 1 mg/L) in the process effluent. Steady-state data were collected to enable process scale-up. This study confirmed that the biological GAC FBR is an environmentally acceptable waste treatment configuration for the destruction of aqueous-phase DCM.

Keywords: Waste, Water, Dichloromethane, Methylene Chloride, Biodegradation, Fluidized-Bed Reactor, Activated-Sludge Inoculation, Granular Activated Carbon Adsorption

Kuo, J.F., Stahl, J.F., Chen, C.L. and Bohlier, P.V. (1998), Dual role of activated carbon process for water reuse. Water Environment Research, 70 (2), 161-170.

Full Text: W\Wat Env Res70, 161.pdf

Abstract: Four granular activated carbon (GAC) filters went into service in 1977 at the County Sanitation Districts of Los Angeles County’s Pomona Water Reclamation Plant to treat 0.44 m³/s (10 mgd) of wastewater for reuse. This article provides long-term operational information for similar water reuse applications. The GAC filters successfully served dual roles as tertiary filters and adsorbers of organics. After 10 regenerations with an average 10% makeup of virgin carbon per regeneration, the iodine number dropped from 1 000 mg/g to a leveled-off value of 600 mg/g; the molasses number increased from 170 to 250; apparent density decreased slightly; and mean particle diameter decreased from 1.65 mm to 1.2 mm. The ash content increased steadily from the initial 6.5% to more than 15% after 15 regenerations. After 20 regenerations, the GAC filters still exerted a total organic carbon removal from more than 80% initially to a level of 20%. The removal of true color by the regenerated carbon decreased from 90% initially to 30%. With the provisions of an afterburner and a wet Venturi scrubber, the air emissions from the carbon regeneration facility were effectively controlled. The energy and labor costs become the dominant operation and maintenance costs as the regeneration frequency increases.

Keywords: Activated Carbon, Water Reuse, Filtration, Adsorption, Tertiary Treatment

Yum, K.J. and Peirce, J.J. (1998), Biodegradation kinetics of chlorophenols in immobilized-cell reactors using a white-rot fungus on wood chips. Water Environment Research, 70 (2), 205-213.

Full Text: W\Wat Env Res70, 205.pdf

Abstract: This research investigated the ability of wood-chip reactors seeded with a white-rot fungus (Phanerochaete chrysosporium) to degrade hazardous substances (4-chlorophenol [4-CP] and 2,4-dichlorophenol [2,4-DCP]). Batch-reactor tests were conducted using 4-CP as a model compound to evaluate the effect of carbon and nitrogen deficiencies on the ability of white-rot fungus immobilized on wood chips to degrade 4-CP. The white-rot fungus degraded 4-CP (71.1 to 83.0%) under all tested conditions including the non-glucose and non-nitrogen conditions. However, there are differences in the degradation percentage of 4-CP using the different growing conditions. The degradation of 4-CP occurs to the greatest extent in the non-glucose/with-nitrogen condition (15.38 ppm/h . g of specific biodegradation rate). Continuous-flow packed-bed reactor tests are conducted using 2,4-DCP as a model compound to evaluate the inhibition effect of 2,4-DCP on the biodegradation enzymes in wood-chip reactor systems, and the inhibition effects seem to be present. The inhibition kinetics of 2,4-DCP are successfully modeled with the mass-balance equation of plug-flow reactors and a substrate-inhibition equation for the reaction rate, yielding an inhibition constant, K-i of 69.8 ppm and a maximum 2,4-DCP concentration, [S](max), of 48.9 ppm at the highest reaction rate. The importance of these results is that the substrate-inhibition model can be used to explain the inhibition effect of 2,4-DCP on the biodegradation enzymes in this wood-chip reactor system. This study points to the potential of continuous-flow reactors using wood chips as a carbon source to degrade toxic chemicals with high-degradation efficiency.

Keywords: Wood-Chip Reactor, White-Rot Fungus, 4-Chlorophenol, 2,4-Dichlorophenol, Continuous-Flow Packed-Bed Reactor, Substrate-Inhibition Model, Basidiomycete Phanerochaete-Chrysosporium, Environmental-Pollutants, Manganese Peroxidases, Lignin Peroxidases, Degradation, 2-Chlorophenol, Parameters, System

Delgado, A., Anselmo, A.M. and Novais, J.M. (1998), Heavy metal biosorption by dried powdered mycelium of Fusarium flocciferum. Water Environment Research, 70 (3), 370-375.

Full Text: W\Wat Env Res70, 370.pdf

Abstract: The biosorption capacity of dead biomass of Fusarium flocciferum for copper (Cu), cadmium (Cd), and nickel (Ni) was studied with the aim of developing the basis for an industrial effluent treatment. It was verified that a Langmuir isotherm describes well the biosorption of cadmium and nickel, whereas copper showed a more irregular behavior. Estimated maximum uptake, Q_max, expressed as mgmetal/100 mgbiosorbent, was 19.2 for cadmium and 5.2 for nickel. Maximum reproducible values for copper biosorption were between 4 and 6 mg/100 mg. Ln this case, it was verified that process efficiency depends on the balance between biosorbent and metal initial concentrations. Studies with different contact times showed that the process was completed within a few minutes. No difference in biosorbent metal affinity was found for cell incubation periods ranging from 24 hours to 4 days, but the biosorbent obtained from older cultures showed a decrease in metal removal capacity. This biosorbent is prepared from a fast-growing fungus with low nutritional and physical requirements. It can be used to remove metals from very dilute solutions at neutral pH values, as in the final steps of heavy metal removal from industrial wastewaters.

Keywords: Saccharomyces-Cerevisiae, Binding, Adsorption, Cu(II), Biosorption, Fusarium Flocciferum, Fungus, Heavy Metals, Copper, Cadmium, Nickel, Adsorption

Wang, J.M., Huang, C.P., Allen, H.E., Takiyama, L.R., Poesponegoro, I., Poesponegoro, H. and Pirestani, D. (1998), Acid characteristics of dissolved organic matter in wastewater. Water Environment Research, 70 (5), 1041-1048.

Full Text: W\Wat Env Res70, 1041.pdf

Abstract: The presence of dissolved organic matter (DOM) in a wastewater treatment system can significantly affect the uptake of heavy metals by sludge particulates. The characteristics of DOM, its concentration, and the solution pH are important parameters governing the heavy metals uptake reaction. The characteristics of DOM of various wastewater and sludge (primary, secondary, and tertiary) samples collected from four municipal wastewater treatment plants were investigated. Results showed that the dissolution of DOM from sludge is significantly affected by pH and suspended solids concentration. Results also showed that DOM contains two discrete acid groups that are available for metals complexation. The site concentration and acidity constants were determined by an alkalimetric titration method. For all DOM samples studied, the acidity constants, pK(aA) and pK(aB), were 5.3 and 9.5, respectively. Based on the acidity constants and the Fourier transform infrared spectra, it is believed that the acid sites consist of carboxylic and amino functional groups. The density of the first acid site was approximately 10^-5 mol/mg chemical oxygen demand for all samples studied. However, the density of the second acid site varied significantly among the DOM samples investigated.

Keywords: Wastewater, Sludge, Dissolved Organic Matter, Acid Sites, Acidity Constants, Functional Groups, Heavy Metals, Heavy-Metals, Activated-Sludge

? Lee, M.W. and Park, J.M. (1998), Biological nitrogen removal from coke plant wastewater with external carbon addition. Water Environment Research, 70 (5), 1090-1095.

Full Text: 1998\Wat Env Res70, 1090.pdf

Abstract: Coke plant wastewater containing high concentrations of ammonia and toxic compounds such as phenol and cyanide was treated using a biological nitrogen removal (BNR) system comprising carbon removal, nitrification, and dentrification stages. The objective of this study was to investigate the feasibility of complete ammonia removal from the coke plant wastewater using a sequential BNR process with external carbon addition. Sodium acetate was introduced as an external carbon source to the denitrification stage after oxidation of phenol and other carbonaceous compounds in the carbon-removal stage. The efficiency of denitrification was strongly affected by the loading rate of the external carbon source, and its optimal rate was determined based on the ratio of chemical oxygen demand to nitrate- and nitrite-nitrogen (COD:NOx-N) of the denitrification stage. The overall removal efficiency of major soluble pollutants in the wastewater was greater than 95% in the BNR system. When a step input of phenol was introduced to check the stability of the overall system, the nitrification was markedly inhibited because of the incomplete degradation of phenol in the carbon-removal stage. However, after this brief inhibition, the nitrification stage recovered to its normal efficiency within 18 days.

Keywords: Biological Nitrogen Removal System, Carbon Addition, Coke Plant Wastewater, Cyanide, Degradation, Denitrification, External Carbon Addition, Nitrate, Nitrification, System Stability, Wastewater, Water

Daigger, G.T. and Sadick, T.E. (1998), Evaluation of methods to detect and control nitrification inhibition with specific application to incinerator flue-gas scrubber water. Water Environment Research, 70 (7), 1248-1257.

Full Text: W\Wat Env Res70, 1248.pdf

Abstract: Two procedures for determining the maximum specific growth rate of nitrifying bacteria in the presence of inhibitors were evaluated. One procedure uses a population of nitrifying bacteria and a short-term (6-hour) batch assay to determine the impact of the test wastewater on the maximum specific growth rate of the nitrifiers. The difference in the specific nitrification rate for the subject population between a control and the test wastewater quantifies the effect of the constituents in the test wastewater on the nitrifier maximum specific growth rate. The second procedure uses batch fill-and-draw bioreactors operated under steady-state conditions to determine the minimum mean cell residence time for growth of the nitrifiers. The need to assess nitrification inhibition at two large municipal wastewater treatment plants provided the opportunity to evaluate these two procedures. Incineration of biosolids is practiced at both of these plants, and it was shown that in-plant recycle of the multiple-hearth flue-gas scrubber water can be inhibitory to nitrification. Results from extensive testing indicated that hydrocyanic acid (HCN), present in the scrubber water, is the probable inhibitor. Consistent results were obtained at both plants. They indicated that HCN concentrations on the order of 0.1 to 0.2 mg/L resulted in a reduction in the nitrifier maximum specific growth rate of approximately 50[percent]. Treatment methods were evaluated at each plant and implemented. At one plant, aerobic biological treatment of the incinerator sidestream is being practiced. At the other facility, cyanide is thermally destroyed in afterburners before contact with the wet scrubbing system.Reprinted by permission of the publisher.

Guibal, E., Milot, C. and Roussy, J. (1999), Molybdate sorption by cross-linked chitosan beads: Dynamic studies. Water Environment Research, 71 (1), 10-17.

Full Text: W\Wat Env Res71, 10.pdf

Abstract: Chitosan, a biopolymer extracted from crustacean shells, exhibits high sorption capacities for metal ion recovery. Sorption efficiency and removal rates are controlled by several diffusion mechanisms. Chitosan gel beads have been prepared and have shown enhanced sorption performance in batch systems. This study shows that, in continuous systems. sorption capacities can reach 700 mg/g, a level close to that obtained in batch studies. The effects of metal concentration, how velocity, and column size are investigated and demonstrate that, because of diffusion mechanisms, the optimum concentration range is approximately 50 to 100 mg/L. In column systems, the Blot number, though greater than 1, is lower than the Blot number obtained in batch systems, indicating that external mass transfer influences mass transfer at the low superficial velocity investigated in this work (0.5 to 2 m/h).

Keywords: Metal-Ions, Rhizopus-arrhizus, Aqueous-Solutions, Calcium Alginate, Uranyl Ions, Equilibrium, Biosorption, Adsorption, Diffusion, Cadmium, Molybdate, Chitosan, Gel Beads, Diffusion, Adsorption, Dynamic Removal, Flow Velocity, Column Depth, Concentration Effect

Min, J.H. and Hering, J.G. (1999), Removal of selenite and chromate using iron(III)-doped alginate gels. Water Environment Research, 71 (2), 169-175.

Full Text: W\Wat Env Res71, 169.pdf

Abstract: Oxyanionic contaminants, specifically selenium and chromium(VI), were removed from solution by sorption onto gel beads formed by pretreating the biopolymer alginic acid with calcium and iron(III). The calcium-iron gel beads were found to be effective at removing selenium(IV) from solution. Chromium(VI) removal was less effective and the rate of sorption was slower than that of selenium(IV). Al an initial selenium(IV) concentration of 400 µg/L (5.1 µM), UP to approximately 94% removal of selenium from solution was achieved by a 120-hour equilibration with 20 calcium-iron beads (10 mg/L or 180 µM total iron). Optimal selenium(IV) removal and stability of the calcium-iron beads were achieved at pH 4. Selenium(IV) sorption and kinetics data were comparable with those observed previously for arsenic(V). Selenium(IV) sorption data, as a function of dissolved concentration and iron content, were modeled. As calcium-iron beads became saturated, the extent of sorption of selenium(IV) or arsenic(V) was decreased by the presence of competing contaminant oxyanions or nonhazardous inorganic anions such as phosphate.

Keywords: Oxyanion, Selenite, Chromate, Biopolymer, Alginate, Gel Bead, Iron(III)-Doped, Removal, Wastewater, Waste-Water, Hexavalent Chromium, Adsorption, Oxide, Acid, Generation, Reduction, Hydroxide, Sorption, Recovery

Tokunaga, S., Yokoyama, S. and Wasay, S.A. (1999), Removal of arsenic(III) and arsenic(V) ions from aqueous solutions with lanthanum(III) salt and comparison with aluminum(III), calcium(II), and iron(III) salts. Water Environment Research, 71 (3), 299-306.

Full Text: W\Wat Env Res71, 299.pdf

Abstract: Interactions of arsenic(III) and arsenic(V) ions with a lanthanum salt were studied with the aim of developing a new precipitation method for removal of arsenic from aqueous solutions. Performance was compared to those of aluminum? polyaluminum chloride (PAC), calcium, and iron(III) salts. Arsenic(III) was removed by iron(LII) and lanthanum in a narrow pH range with less than 60% removal. Arsenic(V) was removed more efficiently by aluminum, PAC, iron(III), and lanthanum. Lanthanum was most effective, meeting Japanese effluent and drinking water standards by adding three times as much lanthanum as arsenic(V). The stoichiometry and X-ray diffraction measurement showed that the precipitation reactions are

La³⁺ + H₂AsO₄- --> LaASO₄ + 2H(+) (pH 5) (1)

and

La³⁺ + HAsO₄- --> LaAsO₄ + H+ (pH 9) (2)

Keywords: Arsenic(V), Arsenic(III), Lanthanum, Iron(III), Aluminum, Calcium, Precipitation, Removal, Solubility Product, Kinetics, Drinking-Water, Precipitation, Arsenate

Sperry, J.M. and Peirce, J.J. (1999), Ion exchange and surface charge on montmorillonite clay. Water Environment Research, 71 (3), 316-322.

Full Text: W\Wat Env Res71, 316.pdf

Abstract: An ion-exchange model originally developed for pure oxides prepared in the laboratory is extended to study of ion exchange and surface charge on a naturally occurring montmorillonite clay. The range of surface charges (-2.010^-6 to 0 mol/m²) measured for montmorillonite with various electrolyte solutions and clay pretreatments is within the range of those measured for a wide variety of oxides prepared in the laboratory (-6.010^-6 to 1.010^-7 mol/m²), including MnO₂-IC1, MnO₂-IC1₂, MnO₂-IC22, titanium dioxide, ferric oxide, and aluminum oxide. In addition, fitted parameter values for lateral interaction constants and equilibrium constants for the acid sites that characterize ion exchange on montmorillonite are on the same order of magnitude as those obtained for pure oxides. Surface charge of montmorillonite in sodium nitrate solution is measured to be approximately 15 to 25% greater than that measured between a pH of 4 and 9 in calcium chloride solution. This difference is attributed to the greater charge on the calcium (2(+)) ion; thus, its stronger electrostatic attraction to the acid hydroxyl site. An order of magnitude change in solids concentration (C-P) can lead to a difference in measured net surface charge density of the same oxide sample of several orders of magnitude. This difference increases at higher pH, indicating the importance of reporting the corresponding C-P at which experiments are conducted.

Keywords: Ion Exchange, Surface Charge, Hydrous Metal Oxides, Montmorillonite Clay, Particle Concentration, Acid-Base, Sorption, Adsorption, Systems, Sediments, Chemicals, Partition, Solids, Model

Reed, B.E., Matsumoto, M.R., Viadero, R., Segar, R.L., Vaughan, R. and Masciola, D. (1999), Physicochemical processes. Water Environment Research,