Showing papers in "Journal of Environmental Engineering in 1992"
TL;DR: In this research, a concept of coverage is defined, and methods on how to locate monitoring stations in a network are described, and the best set of stations is one that maximizes the coverage.
Abstract: The Safe Drinking Water Act requires that the water quality in water distribution systems is to be sampled at locations that are representative of the system; but the act does not describe how the sampling should be done. In this research, a concept of coverage is defined, and methods on how to locate monitoring stations in a network are described. The best set of stations is one that maximizes the coverage. The problems were formulated as integer programming problems, and were solved on a PC using an integer programming code. Two examples of their application to real systems are shown.
232 citations
TL;DR: In this article, the application of electroosmosis (EO) for removal of hydrocarbons from clay was examined, and the results showed that relatively high water solubilities and low distribution coefficients (i.e., benzene, toluene, trichloroethylene (TCE), and m−xylene) are easily removed from Kaolin by EO.
Abstract: This laboratory study examines the application of electroosmosis (EO) for removal of hydrocarbons from clay. EO mobilization is conducted in 7.62‐cm inside diameter (id) glass columns containing 30.48 cm of clay and tap water electrolyte. Iron electrodes are used to impress a 0.4‐volt/cm DC electrical gradient. Destructive sampling of columns following various periods of EO treatment results in breakthrough curves describing relative hydrocarbon contaminant mobilization. EO flushing of dissolved organic chemicals in fine‐grained soils can be predicted using traditional contaminant‐transport equations, which incorporate advection, dispersion, and adsorption. Chemicals with relatively high water solubilities and low distribution coefficients (i.e., benzene, toluene, trichloroethylene (TCE), and m‐xylene) are easily removed from Kaolin by EO. Chemicals with a low water solubility and high distribution coefficient (i.e., hexane and isooctane) are transported from the clay at a slower rate. EO has the potentia...
169 citations
TL;DR: Theoretical fluid transport and chemical reaction equations for one-and two-dimensional fluid flow induced by an electrical field are presented in this paper, where a method of contaminant removal from saturated clay is examined.
Abstract: Theoretical fluid transport and chemical‐reaction equations are presented for one‐ and two‐dimensional fluid flow induced by an electrical field. Laboratory column and two‐dimensional model studies examine electroosmosis (EO) as a method of contaminant removal from saturated clay. Experimental results are compared with theoretical fluid transport and chemical‐reaction relationships. Nutrient‐transport processes are evaluated as a precursor to potential in situ biological treatment of organic contaminants in fine‐grained soil. Laboratory studies are conducted with clay box models and with glass columns packed with low hydraulic‐conductivity soil, including Kaolin, glacial tills, and mixtures of sand and clay. Experimentation shows that saturated clay behaves as an electrochemical cell. Chemical reactions are driven by induced currents. Average flow rates in three‐dimensional systems can be predicted from soil column studies. Electroosmotic conductivity is proportional to soil porosity. Nutrient‐transport s...
119 citations
TL;DR: In this article, a newly identified sorbent that, in terms of composition, is a specialty chelating polymer with immobilized Cu(II) present at the sorption sites is presented, which shows higher selenite and arsenate selectivities over competing sulfate ions.
Abstract: The need for selective sorption of trace concentrations of toxic Se(IV) and As(V) oxyanions, especially in the presence of competing high concentrations of sulfate ions, is well recognized. In this regard, previous investigators have shown the advantages as well as shortcomings of the fixed-bed sorption process when activated alumina or strong-base polymeric anion exchangers are used as sorbents. The present study reports the sorption behaviors of a newly identified sorbent that, in terms of composition, is a specialty chelating polymer with immobilized Cu(II) present at the sorption sites. Experimental results with the new sorbent show higher selenite and arsenate selectivities over competing sulfate ions. Anion exchange accompanied by Lewis acid-base interactions are the underlying reasons for the new sorbent’s enhanced affinities toward arsenates and selenites. In several ways, the new sorbent can complement the shortcomings of activated alumina and other strong-base anion exchangers.
114 citations
Journal Article•
111 citations
TL;DR: In this paper, three different sewage sludges were studied to adapt indigenous sulfuroxidizing microflora to solubilize a substantial part of trace metals from the sludgeges.
Abstract: Twentythree different sewage sludges were studied to adapt indigenous sulfuroxidizing microflora to solubilize a substantial part of trace metals from the sludges. The results showed that the oxida...
85 citations
Journal Article•
68 citations
TL;DR: In this paper, a general waste-load allocation model is developed for which all sets of transfer coefficients are simultaneously incorporated in the water-quality constraint set, and several optimization formulations of this general model are examined to evaluate efficient management solutions that account for a range of possible future conditions.
Abstract: A novel approach for including uncertainty in the water-quality–management process is presented. The approach is based on the use of multiple scenarios that reflect possible combinations of hydrologic, meteorologic, and pollutant loading design conditions. Each scenario, which represents possible “future management design conditions,” defines a set of transfer coefficients that describes the pollutant transport process under these design conditions. A general waste-load–allocation model is developed for which all sets of transfer coefficients are simultaneously incorporated in the water-quality constraint set. Several optimization formulations of this general model are examined to evaluate efficient management solutions that account for a range of possible future conditions. The approach is applied to the management of BOD from 10 dischargers on the Willamette River in Oregon. The results indicate that model formulations based on minimizing a measure of total deviations from a target DO level identify efficient solutions for the waste-load allocation.
66 citations
TL;DR: In this paper, the engineering behavior of one iron and two alum coagulant water-treatment plant sludges was investigated, and the behavior studied included plasticity characteristics, moisture-density relation, compressibility, and shear strength.
Abstract: The engineering behavior of one iron and two alum coagulant water-treatment plant sludges was investigated. The behavior studied included plasticity characteristics, moisture-density relation, compressibility, and shear strength. Additionally, a hypothetical disposal landfill was analyzed and discussed to demonstrate possible applications of the developed data base. The test results indicate that the sludges are extremely plastic and highly compressible. The drained shear strength is high, but the undrained strength is very low. They are also highly sensitive and thixotropic. Compared with the iron sludge, the alum sludges are more plastic and compressible, and have higher undrained shear strength at the same solids content. The moisture-density relation of the iron sludge exhibits the typical one-hump shape, whereas that of the alum sludge shows no peak formation. The results of landfill analysis indicate that the required minimum solids content for maintaining a desired slope is higher for the iron sludge than the alum sludge.
61 citations
TL;DR: In this paper, an improved first-order uncertainty analysis is presented, where the linearization point varies to match the output level whose exceedance probability is sought, and tested on the Streeter-Phelps equation to estimate the probability distribution of critical dissolvedoxygen deficit and critical dissolved oxygen.
Abstract: Uncertainties are unavoidable in water‐quality modeling and subsequent management decisions. Monte Carlo simulation and first‐order uncertainty analysis (involving linearization at central values of the uncertain variables) have been frequently used to estimate probability distributions for water‐quality model output due to their simplicity. Each method has its drawbacks: Monte Carlo simulation's is mainly computational time; and first‐order analysis' are mainly questions of accuracy and representativeness, especially for nonlinear systems and extreme conditions. An improved (advanced) first‐order method is presented, where the linearization point varies to match the output level whose exceedance probability is sought. The advanced first‐order method is tested on the Streeter‐Phelps equation to estimate the probability distribution of critical dissolved‐oxygen deficit and critical dissolved oxygen using two hypothetical examples from the literature. The advanced first‐order method provides a close approxi...
59 citations
TL;DR: In this article, a model for the overall predenitrification process is constructed based on the kinetic model of IAWPRC but allows for temperature and pH dependence of nitrifier growth rate, temperature dependence of selected kinetic parameters for heterotrophic bacteria, and a realistic representation of sludge thickening in the secondary clarifier.
Abstract: A model for the overall predenitrification process was constructed. The model is based on the kinetic model of IAWPRC but allows for temperature‐ and pH‐dependence of nitrifier growth rate, temperature‐dependence of selected kinetic parameters for heterotrophic bacteria, and a realistic representation of sludge thickening in the secondary clarifier. The latter predicts sludge blanket height and solids concentration profiles in the secondary clarifier under both steady‐state and dynamic conditions. The validity of the model was investigated using data from a pilot‐scale predenitrification plant.
TL;DR: In this paper, the optimum height of the inlet aperture increases with both the overflow rate per unit width and the return sludge ratio, but decreases with the relative difference of density.
Abstract: Poor flow in final settling tanks may be the result of neglecting the effects of density current. This can be countered when inserting guiding flow elements, such as the inlet and the barrier walls in the tank. Based on a simple approach, the optimum height of the inlet aperture increases with both the overflow rate per unit width and the return sludge ratio, but decreases with the relative difference of density. Further, a central barrier wall is introduced to divide the tank into high and low sludge concentration units. More generally, the effect of density can be reduced by correctly positioning the inlet structure. These results are verified by selected prototype observations involving measurements of both velocity and concentration fields. A comparison of original and final designs where effects of density were reduced clearly demonstrates significant improvement in sedimentation and effluent characteristics. The present recommendations may easily be incorporated in an existing tank and, thus, are efficient in improving the final sedimentation.
TL;DR: The experimental in situ aquifer biorefraction site at Moffett Field, California, is a small, confined, sand and gravel aquifer, interspersed with layers of silts and clays as mentioned in this paper.
Abstract: The experimental in situ aquifer biorestoration site at Moffett Field, California, is a small, confined, sand and gravel aquifer, interspersed with layers of silts and clays. Laboratory sorption and solids characterization studies were carried out on core material recovered from in and around the aquifer zone. Equilibrium (distribution coefficient Kd) and nonequilibrium (effective pore‐diffusion coefficient Dp) sorption parameters, estimated from batch experiments, were used in one‐dimensional simulations of the breakthrough of three halogenated organic compounds: trichloroethylene (TCE), carbon tetrachloride (CT), and vinyl chloride (VC). Three types of transport models were used: equilibrium partitioning, spherical diffusion, and equivalent first‐order diffusion. The hydrodynamic parameters (dispersion coefficient and pore water velocity) were determined previously using field‐scale tracer tests. Simulations reconfirmed the theory that while an accurate Kd value is required for each compound, it is suff...
TL;DR: In this article, the effects of the inlet densimetric Froude number on the velocity and suspended solids concentration fields in secondary circular clarifiers were investigated by application of a verified numerical approach.
Abstract: The effects of the inlet densimetric Froude number on the velocity and suspended solids concentration fields in secondary circular clarifiers are investigated by application of a verified numerical...
TL;DR: In this article, the authors examined the detail of moisture profiles in three landfills located in semi-arid climates in a Third World country and concluded that one of the components of the water balance that is most difficult to define or estimate is the storage capacity of the refuse body.
Abstract: Waste‐disposal practices in poor Third World communities can have extremely adverse environmental impacts, especially with regard to ground‐water pollution. The water‐balance or water‐budget method has been developed and used to predict leachate production from sanitary landfills. This study examines the detail of moisture profiles in three landfills located in semiarid climates in a Third World country. It concludes that one of the components of the water balance that is most difficult to define or estimate is the storage capacity of the refuse body. This appears to be greatly influenced by the properties and disposition of the layers of intermediate cover. This information is most important for the design of low‐cost, environmentally acceptable landfills for Third World communities. The study also investigates soil moisture suction in landfills and concludes that even in semiarid areas, soil moisture suction in landfills is sufficiently low to enable uninhibited bacteriological activity to take place.
TL;DR: In this article, a multicomponent, nonisothermal model was used to predict the evaporation rates of organic contaminants in unsaturated soils during soil venting, and the model assumptions were verified by one-dimensional column experiments.
Abstract: A multicomponent, nonisothermal model to predict the evaporation rates of organic contaminants in unsaturated soils during soil venting is presented. This model can account for temperature variations in the soil due to heat absorbed during the evaporation and due to provision of heat sources to enhance soil remediation. The model assumptions were verified by one-dimensional column experiments. Experimental results indicated that the venting air is saturated with the contaminant vapor even at high air flow rates. Local temperatures in the soil were found to decrease significantly, during venting of volatile contaminants with relatively high latent heat of vaporization. Condensation of water vapor from the incoming air is found to affect the evaporation rates of the contaminant and the temperature profiles in the soil. Model predictions were in good agreement with the experimental data. The numerical code is used to parametrically study the effects of contaminant volatility and latent heat absorbed during evaporation on the remediation times. Remediation times were found to be underpredicted by isothermal models. It was found that heating the inlet air can enhance remediation only for less volatile contaminants.
TL;DR: The optimization model indicates landfill use characteristics throughout the planning horizon, including the times at which landfills are closed and opened and the amount of waste that is diverted to recycling.
Abstract: A mathematical mode is presented to determine the optimal operation of consecutive landfills while incorporating recycling programs. The model is capable of handling currently available landfills as well as numerous proposed future landfills. Model sensitivity analysis is performed by varying the capacities of present and future landfills, in addition to conventional objective function sensitivity analysis and right‐hand‐side sensitivity. In addition, the model incorporates the possible utilization of recycling programs. The model is driven by overall long‐term costs of operation. The optimization model indicates landfill use characteristics throughout the planning horizon, including the times at which landfills are closed and opened and the amount of waste that is diverted to recycling. Model solutions also indicates that recycling options may be implemented even though recycling costs exceed the cost of the current disposal option, in order to extend the lifespan of less expensive landfills and to defer...
TL;DR: Based on a comprehensive analysis of four groups of chemical and biological reactions, a general pseudosteadystate mathematical model of the anaerobic digeston buffer system was developed in this article.
Abstract: Based on a comprehensive analysis of four groups of chemical and biological reactions, a general pseudosteadystate mathematical model of the anaerobicdigeston buffer system was developed. According...
TL;DR: In this article, two full-scale municipal FBCs used for softening in southern Florida were sampled and characterized, and the authors concluded that calcium removal is very rapid within the FBC, leaving a large portion of the bed unused at any one time.
Abstract: Fluidized bed crystallizers (FBCs), also called pelletizers or pellet reactors, are an attractive alternative to conventional water softening. FBCs produce a coarse, spherically grained, easily dewatered, calcitic sand as the waste product, rather than a gelatinous sludge. Two operating full‐scale municipal FBCs used for softening in southern Florida were sampled and characterized. The study concludes that: (1) Calcium removal is very rapid within the reactor, leaving a large portion of the bed unused at any one time; (2) the calcium removal rate can be described by the Reddy‐Nancollas crystallization model; (3) high supersaturation levels due to poor mixing at the point of chemical mixing promotes microfloc production and solids carryover in the effluent; (4) classification of the pellets within the fluidized bed does not occur; (5) the sampling techniques appear to be adequate for characterizing FBC reactors; and (6) operation of FBCs would be aided by the installation of a pressure gauge on the FBC inf...
TL;DR: The extent to which different measures of T actually ensure compliance with the required level of inactivation is evaluated by using segregated flow analysis and classical residence time distribution models.
Abstract: The U.S. Environmental Protection Agency has recently promulgated drinking‐water regulations, known as the surface water treatment rule (SWTR), to control viruses, Giardia cysts, Legionella, and heterotrophic bacteria. The SWTR specifies overall minimum removal/inactivation efficiencies by filtration and disinfection for Giardia lamblia and viruses and uses the CT concept to predict in‐activation efficiencies. CT stands for the product of characteristic exposure time (T) and the characteristic concentration (C) in the disinfection chamber. This paper evaluates possible methods to determine the characteristic exposure time for ozone disinfection. The extent to which different measures of T (such as the hydraulic retention time, T10 and T50) actually ensure compliance with the required level of inactivation is evaluated by using segregated flow analysis and classical residence time distribution models. The analysis indicates that T10, the minimum exposure time of 90% of the water in the disinfection unit, i...
TL;DR: Nitrobacter was used successfully as a test organism, and the serum bottle technique presented in this paper is an effective and simple method for determining the 50% inhibition concentration of toxic chemicals.
Abstract: Concern for the effects of toxic chemicals on the environment leads the search for better bioassay test organisms and simpler test procedures. Nitrobacter was used successfully as a test organism, and the serum bottle technique presented in this paper is an effective and simple method for determining the 50% inhibition concentration (IC50) of toxic chemicals. A total of 43 phenols, benzenes, and aliphatics, including many chlorinated chemicals, were used in the experiments. The test results (IC50) correlate well with the quantitative‐structure‐activity‐relationship parameters, such as log P, the solvatochromic parameters, and molecular connectivity indexes. Specifically, the QSARs (either with log P or with log S) for nonphenolic toxicants may be used to predict potential toxicity to Nitrobacter. The log P QSAR for phenolic toxicants also is adequate. The solvatochromic parameter QSAR correlates well with all toxicants and is free from a collinearity problem. The molecular connectivity indexes QSAR for ea...
TL;DR: In this paper, the authors present an analysis of ways to characterize ozone concentration in water disinfection systems for the purpose of calculating ozone inactivation efficiencies, using the concept of characteristic exposure time and characteristic concentration of the disinfectant in the disinfection chamber.
Abstract: The U.S. Environmental Protection Agency (EPA) has recently promulgated drinking water regulations known as the surface water treatment rule (SWTR) to control viruses, \IGiardia lamblia, Legionella\N, and heterotrophic bacteria. The SWTR specifies overall minimum removal and inactivation efficiencies by filtration and disinfection for \IGiardia lamblia\N and viruses. The \ICT\N concept is used to predict inactivation efficiencies. \ICT\N stands for the product of characteristic exposure time (\IT\N) and the characteristic concentration (\IC\N) of the disinfectant in the disinfection chamber. This paper presents an analysis of ways to characterize ozone concentration in water disinfection systems for the purpose of calculating ozone inactivation efficiencies. Guidelines to predict the characteristic (or average) ozone concentration are developed for four types of ozone reactors, including rigorously mixed systems, cocurrent and countercurrent contractors, and flow segments (i.e., where no ozone gas is introduced but where residuals in a water phase remains).
TL;DR: In this article, an integrated assessment model is used to estimate SO2 emission effects on regional lake acidification and fish viability in two regions of North America (Adirondack Park, New York, and the Boundary Waters region of northern Minnesota).
Abstract: An integrated assessment model is used to estimate SO2 emission effects on regional lake acidification and fish viability in two regions of North America (Adirondack Park, New York, and the Boundary Waters region of northern Minnesota). An uncertainty analysis is employed to estimate the likely range of possible impacts. Based on emission projections for the United States and Canada, lake acidification in these two regions appears likely to improve slowly over the next two decades. An acid‐rain control program will accelerate the recovery of acidic lakes at Adirondack Park, with a projected decrease over the no‐control case of approximately 2–11% in the number of lakes below pH 5.5 and a 0.4–6% increase in the number of lakes potentially able to support brook or lake trout by the year 2010. For Boundary Waters, the expected improvements are negligible since deposition levels are relatively low. Our analysis does demonstrate a potential for larger or smaller improvements in these two regions, with lower pr...
TL;DR: In this paper, the authors evaluated the performance of various mass load estimators for a range of tributary types including highly responsive systems by conducting retrospective studies with comprehensive sets of field data for total phosphorus concentration and discharge.
Abstract: Annual mass load estimators are evaluated for application to a range of tributary types including highly responsive systems. Evaluations are performed by conducting retrospective studies with comprehensive sets of field data for total phosphorus concentration and discharge. Four estimators from three broad categories are selected for study based on their performance in previous research. Extimators are evaluated using Monte Carlo sampling studies in which load estimates made from random subsamples are compared to true loads calculated from a complete loading record. The performance of the estimators differs strongly among the tributary test cases. Hydrograph characteristics and/or concentration/discharge relationships appear to play a strong role in the precision of all of the estimators and in the bias of averaging and regression estimators. Beale's ratio estimator is the only estimator to provide unbiased estimates for both stable and responsive systems, although stratification is necessary under event ...
TL;DR: In this paper, a model is developed to simulate the behavior of a reactor that exhibits suspended and attached growths under a completely mixed condition, where a single substrate is used competitively by both growths at steady state.
Abstract: A model is developed to simulate the behavior of a reactor that exhibits suspended and attached growths under a completely mixed condition. This model assumes that a single substrate is used competitively by both growths at steady state. While kinetic parameters, reactor porosity, and medium-specific surface are given, the model predicts performance of such a reactor through the use of two fundamental parameters: empty-bed hydraulic retention time and suspended-biomass solid retention time. An example is illustrated to demonstrate the use of this model.
TL;DR: In this paper, the effects of jet orientation and jet momentum on mixing processes and efficiency were investigated for artificial mixing of naturally temperature-stratified water bodies such as lakes, reservoirs, and ponds, by selective withdrawal and jet reinjection at a different depth.
Abstract: This paper deals with artificial mixing of naturally temperature-stratified water bodies, such as lakes, reservoirs, and ponds, by selective withdrawal and jet reinjection at a different depth. The effects of jet orientation and jet momentum on mixing processes and efficiency are investigated. A one-dimensional simulation model, previously verified against experimental data for horizontal jets, is applied to experimental data for vertical jets in this paper. It is found that destratification by a vertical jet is slightly more efficient than by a horizontal jet. Destratification is measured by a stability parameter. More than 80% mixing is achieved when 20% or more of the water volume between withdrawal and reinjection points is recycled. Low-momentum jets are found more efficient than high-momentum jets. Efficiency was measured in terms of energy demand relative to change in potential energy. Basins of rectangular or parabolic shape are investigated.
TL;DR: In this article, a rotating disk test system (RDTS) was used to measure the adhesion strength of small mussels (≈1mm) to four materials [polyvinylchloride (PVC), polymethylmethacrylate (PMMA), stainless steel (SS), and aluminum (AL)].
Abstract: Zebra mussels adhere tenaciously and gregariously to hard surfaces, thereby fouling water‐processing facilities and equipment. At present, there are few data on zebra mussel adhesion strength to common substrates. A rotating disk test system (RDTS) was used to measure the adhesion strength of small mussels (≈1mm) to four materials [polyvinylchloride (PVC), polymethylmethacrylate (PMMA), stainless steel (SS), and aluminum (AL)].Adhesion strength varied significantly with material but only marginally with residence time (one, two, seven, 14, 21, and 28 days). The estimated shear stress required to remove 95% of mussels (τ95%) averaged 62±5Pa (mean±standard error, n=6 disks) on PVC, 50±3Pa on PMMA, 48±4Pa on SS, and 31±1(n=4)Pa on AL. τ95% peaked on the second day (85 Pa on PVC, 65 Pa on PMMA, 57.5 Pa on SS, 32.5 Pa on AL), then decreased to a constant level. Ultimately, this research should provide insight into material selection and designs that minimize attachment and facilitate removal of zebra mussels.
TL;DR: In this paper, the authors deal with the various aspects of deep-bed filtration modeling and the appropriate use of deepbed models to aid the modeler in achieving simulation objectives.
Abstract: A large number of deep‐bed filtration models have been proposed since the contributions of Iwasaki (1937). The reason behind the development of several deep‐bed filtration models has been the continuing necessity for a better description of the variation of the filtrate quality and the head‐loss development with the filter depth. These models are initially calibrated using observations of the filtrate quality and the head‐loss variation from pilot filter runs, and are then subsequently used to simulate the performance of operational filters. In view of the large number of models of deep‐bed filtration and the existence of conflicting remarks about the uses of many of these, the selection of the most appropriate deep‐bed filtration model and its proper use in the simulation process becomes an important issue. The present study deals with the various aspects of deep‐bed filtration modeling and the appropriate use of deep‐bed filtration models to aid the modeler in achieving simulation objectives.
TL;DR: In this paper, a design method for a wastewater disposal scheme suitable for coastal communities in both developed and developing countries is presented, which exploits the natural flushing mechanisms of estuaries to pump effluent out of the estuary and away from the coast, by placing the outfall within an estuary near the mouth and timing the waste discharge to coincide with the ebbing tide.
Abstract: A design method is presented for a wastewater disposal scheme suitable for coastal communities in both developed and developing countries. The disposal technique exploits the natural flushing mechanisms of estuaries to pump effluent out of the estuary and away from the coast. By placing the outfall within an estuary near the mouth and timing the waste discharge to coincide with the ebbing tide, two advantages ensue: (1) Upstream transport is avoided; and (2) the chance of effluent being re‐entrained at the entrance is minimized. Where there are sensitive environmental targets between the outfall and entrance, Monte Carlo simulation of the transport dispersion processes within the channel is used to predict the distribution of pollutant concentration and, hence, the standard of treatment required. Timing of the discharge cycle is determined by consideration of the dynamics of the ebb and flood flow patterns at the channel entrance. The method is applied to a case study being considered for New South Wales,...
TL;DR: In this article, the use of the semidiscrete Galerkin finite element method with an asymmetric interpolating function was found to eliminate this spatial oscillation, resulting in a computationally efficient algorithm.
Abstract: Adsorption onto activated carbon in a fixed‐bed reactor has been found to be an attractive process for removing hazardous organics from water and wastewater. Current fixed‐bed reactor design procedures can be both expensive and time‐consuming. Mathematical process modeling can reduce the cost and time by decreasing laboratory and pilot‐scale experimentation. A model will provide the most utility if it is computationally efficient, and both stable and accurate for a wide variety of system conditions. A global method of orthogonal collocation is currently favored over finite differences. This method, however, results in an unstable algorithm as a result of spatial oscillation. The use of the semidiscrete Galerkin finite‐element method with an asymmetric interpolating function was found to eliminate this spatial oscillation, resulting in a computationally efficient algorithm. A relationship was developed that allows the optimum value of the asymmetric parameter to be determined. This results in a stable algo...