Showing papers in "Journal of the Environmental Engineering Division in 1981"
TL;DR: In this paper, an optimization technique is presented for use in planning and designing looped water distribution systems, which is iterative, employing linear programming and a gradient procedure; and it produces a locally optimal solution.
Abstract: An optimization technique is presented for use in planning and designing looped water distribution systems. The technique is iterative, employing linear programming and a gradient procedure; and it produces a locally optimal solution. A demonstration using data for the New York City water supply system, shows a potential cost saving of 13 percent for the solution obtained using the new method, in comparison to the best design developed in an earlier study.
272 citations
TL;DR: A kinetic model is developed for determining substrate flux into biofilms with known thicknesses, even though the thickness may be of nonsteady state, and successfully predicted the column performance, except for cases in which oxygen depletion caused dual-substrate limitation.
Abstract: A kinetic model is developed for determining substrate flux into biofilms with known thicknesses, even though the thickness may be of nonsteady state. The critical contribution of this model is that mass transport resistance is explicity included in order that the flux becomes a direct function of the bulk substrate concentration. Laboratory-scale, column reactors were utilized to culture steady-state biofilms of known thicknesses. Subsequently, the influent flow rate or substrate concentration was changed to determine the short-term kinetics of substrate utilization of biofilms of known thicknesses. The model successfully predicted the column performance, except for cases in which oxygen depletion caused dual-substrate limitation. Removal of substrate to very low levels was only possible during short-term experiments when the biofilm was in net decay.
175 citations
TL;DR: In this paper, the sphericity of the material greatly influences the fluidization behavior of the media and it influences the fixed bed head loss, minimum fluidization velocity, and the expansion of media as a function of upflow rate.
Abstract: Granular media filtration is of growing importance in both water and wastewater treatment. A variety of filter media are being adopted for some filters. The common filter materials (sand, anthracite, garnet, illmenite) are all angular in shape. Some have low sphericity (very angular) while others have high sphericity. The sphericity of the material greatly influences the fluidization behavior of the media. It influences the fixed bed head loss, the minimum fluidization velocity, and the expansion of the media as a function of upflow rate. All of these are important design aspects in backwashing of filters. The physical properties of the several common filter materials are presented, including the sphericity, density and porosity. The Wen and Yu equation is adequate for predicting minimum fluidization velocity for all of the filter media studied. A new model for predicting expansion of filter media is presented which includes the sphericity or dynamic shape factor of the filter media as explicit variables.
77 citations
TL;DR: In this paper, a theoretical and experimental investigation was attempted to determine floc strength quantitatively, and some formulas were presented to evaluate the hydrodynamical forces acting on a suspended floc particle, depending on the flow conditions and the particle Reynolds number values.
Abstract: A theoretical and experimental investigation was attempted to determine floc strength quantitatively. Some formulas were presented to evaluate the hydrodynamical forces acting on a suspended floc particle, depending on the flow conditions and the particle Reynolds number values. The assumption of a pseudosurface tension allowed the calculation of a value for the inherent strengths of flocs.
69 citations
TL;DR: In spite of the abundance of mathematical models for solid waste management, planners and decision makers have been reluctant to use such models due to the difficulties in understanding and implementing them as discussed by the authors.
Abstract: In spite of the abundance of mathematical models for solid waste management, planners and decision makers have been reluctant to use such models due to the difficulties in understanding and implementing them. An Environmental Protection Agency sponsored computer program, Waste Resource Allocation Program (WRAP), is aimed at this problem. WRAP greatly facilitates regional solid waste planning with its simple input requirements and clear output. By using Walker's fixed charge linear programming algorithm, WRAP occasionally finds global optima even to solid waste management schemes that are formulated as capacitated transshipment networks with concave costs and flows with losses. A case study using Region J in North Carolina is presented.
59 citations
TL;DR: In this paper, a modeling procedure was developed to estimate nonpoint source pollution from agricultural runoff in large watersheds based on simple equations for runoff and soil loss prediction, which is designed for use in situations where resources are not available for extensive water quality sampling or more sophisticated modeling efforts.
Abstract: A modeling procedure has been developed to estimate nonpoint source pollution from agricultural runoff in large watersheds. The procedure is based on simple equations for runoff and soil loss prediction. It is designed for use in situations where resources are not available for extensive water quality sampling or more sophisticated modeling efforts. The simple models or loading functions were tested by comparing predicted and observed nitrogen and phosphorus mass fluxes in streamflow from a 391-km² Pennsylvania watershed for a 16-month period. The comparisons indicated that loading functions provided reasonable estimates of dissolved nitrogen, solid-phase nitrogen and total phosphorus mass fluxes in runoff from the watershed. Rather, these simple methods are most suitable as screening devices to: (1)Identify the approximate magnitudes of nonpoint source loading of pollutants in agricultural runoff; and (2)evaluate the likely changes in loadings associated with alternative agricultural management practices.
58 citations
TL;DR: Aquatic treatment systems can be designed to produce effluents meeting secondary and typical advance treatment effluent requirements on BOD, SS, and nitrogen compounds as discussed by the authors, which can be more cost effective than conventional treatment processes to achieve these wastewater treatment objectives.
Abstract: Aquatic treatment systems can be designed to produce effluents meeting secondary and typical advance treatment effluent requirements on BOD, SS, and nitrogen compounds. In many situations, particularly those where the climate is mild or effluent requirements are seasonal, aquatic systems will be more cost effective than conventional treatment processes to achieve these wastewater treatment objectives. The feasibility of using aquatic systems to remove other contaminants common in domestic wastewaters has not been determined conclusively. It appears that their use in these applications will be limited. Site-specific factors will affect the performance of an aquatic system. The nature and probability of occurrence of these effects can not be predicted adequately from the data and design criteria reported to date. Consequently, pilot-scale studies to develop site-specific aquatic system design criteria and to verify system performance should be conducted prior to construction of a full-scale aquatic treatment system.
57 citations
TL;DR: In this paper, a model consisting of a dispersed flow active zone and a fully-mixed return flow zone is developed and calibrated to evaluate the treatment performance of waste stabilization ponds.
Abstract: Treatment performance of waste stabilization ponds is a function of both the hydraulic transport and the biological and chemical transformation processes within the pond. Both the efficient hydraulic design of these ponds and the appropriate mathematical models for describing the hydraulic transport process are identified. A model consisting of a dispersed flow active zone and a fully-mixed return flow zone is developed and calibrated. Dye tracer studies and model simulations are utilized to illustrate the treatment efficiency of various pond geometries and inlet and outlet configurations. Recommendations are made for optimum design. For certain of the ponds analyzed, treatment efficiency predicted by the completely-mixed flow model compares well with that determined by analysis of dye tracer studies. The plug flow assumption seriously overestimates treatment efficiency.
54 citations
TL;DR: Water hyacinths have the capability of producing secondary or advanced secondary effluents, such as heavy metals and synthetic organic chemicals, which can be biologically concentrated in aquatic macrophytes systems as mentioned in this paper.
Abstract: Wastewater treatment systems using water hyacinths have the capability of producing secondary or advanced secondary effluents. Hyacinths also have the potential for producing effluents meeting advanced waste treatment standards if optimum plant harvesting techniques and supplemental methods for additional phosphorous removal are developed. Widespread use of hyacinth systems will be confined to relatively warm climates because growth ceases at water temperatures below 50°F (10°C). Treatment facilities using duckweed could be used in colder climates, however, systems using this plant are in a very preliminary stage of development. In addition to the removal of conventional pollutants, aquatic macrophytes systems also have the capability of biologically concentrating heavy metals and synthetic organic chemicals. Preliminary cost analyses indicate water hyacinth systems could be more economical than comparable land or conventional treatment techniques.
50 citations
TL;DR: The Storm and Combined Sewer (SCS) Program of the United States Environmental Protection Agency Municipal Environmental Research Laboratory began a modest effort to fill this data void as discussed by the authors, which was later extended to a larger scale.
Abstract: Receiving water impacts are a major national concern. We are spending billions of dollars on secondary treatment plants, meanwhile major contributors, such as stormwater and combined sewer overflows, are still uncontrolled. To attain the goals set forth in PL 92-500 and PL 95-217 in an economical and efficient manner, those analyzing, planning, and designing controls must have an understanding of the impact of pollutants on receiving waters. Ties between receiving water quality and stormwater discharges must be clearly established and delineated. Therefore, several years ago, the Storm and Combined Sewer (SCS) Program of the United States Environmental Protection Agency Municipal Environmental Research Laboratory began a modest effort to fill this data void. A brief history of the SCS Program's receiving water impact projects is presented, emphasizing an overview of ongoing and recently completed projects, including significant results. Also, Program needs and areas of anticipated effort are analyzed.
45 citations
TL;DR: An analysis of enteroviral inactivation by ozone was performed using kinetic expressions developed from mass balance information obtained from a continuous flow reactor to suggest that the viral inactivation reaction is controlled by mass transfer of ozone through the viral protein coat.
Abstract: An analysis of enteroviral inactivation by ozone was performed using kinetic expressions developed from mass balance information obtained from a continuous flow reactor. The rate of viral inactivation was observed to be directly proportional to the residual ozone concentration and the density of viruses raised to the power of 0.69. The effect of temperature on the rate of viral inactivation was evaluated using Arrhenius and Eyring's equations. The activation energy and entropy of the overall inactivation reaction were observed to be 3.6 kcal and -13.66 cal/uaoK, respectively. The low value of activation energy implies that the viral inactivation reaction is controlled by mass transfer of ozone through the viral protein coat. The negative value of entropy indicates that a more orderly arrangement of viral molecules occurred during the ozone inactivation process.
TL;DR: In this article, a mathematical model of time-varying salinity distribution is selected and further developed for the purpose of calculating over a period of time equal to a year or more.
Abstract: A mathematical model of time-varying salinity distribution is selected and further developed for the purpose of calculating over a period of time equal to a year or more. These calculations are required to evaluate the effects of different scenarios or plans involving reservoir regulation and consumptive freshwater withdrawals. The tidal estuary portion of the Delaware River is the subject of this application. A hydrodynamic and coupled salinity model is described in terms of its governing equations. The model is one-dimensional and contains a dispersion relationship which is predictive over a broad range of tidal and freshwater inflow conditions. Treatment of boundary conditions is described with respect to the processing of large amounts of data and with respect to the definition of the salinity concentration of tributary and upstream inflows. A comparison is given between calculated and observed concentrations over a year-long period.
TL;DR: In this paper, an anaerobic filter with granular activated carbon serving as a contact medium was used to reduce the phenolic content of a synthetic catechol bearing wastewater.
Abstract: An innovative energy efficient process has been developed for the effective degradation of phenolic compounds. The treatment process, which consists of an anaerobic filter with granular activated carbon serving as a contact medium, effectively reduces the phenolic content of a synthetic catechol bearing wastewater. Degradation of another phenolic compound, o-cresol, was not realized. The o-cresol exhibited no inhibition to the formation of methane as a result of the breakdown of other organic cosubstrates—glucose, sodium citrate and an ethanol vitamin extract. The potential of the treatment process in the treatment of coal conversion wastewaters is currently under investigation.
TL;DR: The continuing restoration program for polluted, hypereutrophic Onondaga Lake, including descriptions of ecosystem responses to reclamation measures and evaluations of various characteristics specific to the lake as they may affect future responses are examined in this paper.
Abstract: The continuing restoration program for polluted, hypereutrophic Onondaga Lake, is examined, including descriptions of ecosystem responses to reclamation measures and evaluations of the various characteristics specific to the lake as they may affect future responses. Major responses to the program have included: (1)Substantial changes in phytoplankton composition; (2)reduction in concentrations of heavy metals; and (3)a dramatic increase in zooplankton biomass. Despite a major reduction in phosphorus loading, phytoplankton biomass has remained essentially unchanged. Further reductions in phosphorus loading, anticipated with the new (1981) tertiary sewage treatment plant, may result in phosphorus limited phytoplankton growth. The increase in zooplankton implies increased phytoplankton turnover rates and phosphorus recycling within the lake, which may prolong future phytoplankton blooms.
TL;DR: In this article, two nonlinear programing techniques for analyzing nonsteady state aeration test data are presented, which can be used to obtain indentical parameter estimates for non-stationary state reaeration testing.
Abstract: Estimating the oxygen transfer rate of an aeration system is one of the more important functions of a process design engineer. Underestimating the oxygen transfer rate of a proposed aeration system results in an overdesigned system which may be energy intensive and expensive to operate. Overestimating the oxygen tranfer rate results in inadequate oxygen transfer and reduced process efficiency. Two nonlinear programing techniques for analyzing nonsteady state aeration test data are presented. Either technique can be used to obtain indentical parameter estimates. Coding is also presented which enables either technique to be implemented using an advanced programmable calculator. Using the techniques presented, nonlinear parameter estimation for nonsteady state reaeration testing can be used in the field.
TL;DR: In this article, a laboratory procedure was developed for testing the leachability of foundry process solid wastes using a shake-flask technique to provide distilled water-foundry waste contact, plus filtration or centrifugation, or both, to separate the resulting liquid for analysis.
Abstract: A laboratory procedure was developed for testing the leachability of foundry process solid wastes. This procedure uses a shake-flask technique to provide distilled water-foundry waste contact, plus filtration or centrifugation, or both, to separate the resulting liquid for analysis. The procedure was used to examine the leaching characteristics of eight different foundry process wastes, each of which had been previously subjected to temperatures ranging from room temperature to temperatures of molten metal. This was done to simulate the burn-out which would actually be experienced with some wastes. The eight wastes exhibited widely different leaching characteristics, but in all cases the amount of matter leached per unit weight of water decreased markedly as the temperature to which the waste was subjected increased. Additional experiments utilizing the shake-flask procedure indicated that progressively larger particles of waste, such as core butts, release less matter to leachate per unit weight of waste than the unagglomerated sand.
TL;DR: In this paper, a simplified design method for submerged filter and expanded bed biofilm reactors was developed, which incorporates limitations of both the electron donor and electron acceptor based upon Monod kinetics, and the stagnant liquid layer at the biofilm surface based upon the packing media and the waste flow rate.
Abstract: A simplified design method is developed for submerged filter and expanded bed biofilm reactors. The method incorporates limitations of both the electron donor and electron acceptor based upon Monod kinetics, and the stagnant liquid layer at the biofilm surface based upon the packing media and the waste flow rate. The model has been programmed so that calculations can be accomplished on a hand-held calculator, offering wide-scale availability to designers. The model consists of two basic processes: diffusion of substrate from the bulk liquid into the biofilm, and transformation of the substrate by bacteria within the biofilm. Conceptually, substrate must diffuse first from the bulk liquid through a stagnant liquid layer at the biofilm surface, and then into the biofilm until reaching a constant concentration, close to zero, at the effective depth.
TL;DR: In this paper, a device has been developed to measure and to make a composite sample of stormwater runoff from highways, which was laboratory calibrated and field tested on a portion of Interstate-5 in Seattle, Washington.
Abstract: A device has been developed to measure and to make a composite sample of stormwater runoff from highways The device was laboratory calibrated and field tested on a portion of Interstate-5 in Seattle, Washington Performance of the composite sampling device has been compared with conventional discrete sampling instruments The major discrepancies between the two systems are due to laboratory and flow measurement errors When these errors are resolved, the performance of the composite and discrete systems are almost identical
TL;DR: The removal of particles in water treatment plants through flocculation, sedimentation, and filtration depends on the design of each treatment process and physical characteristics of the raw water supply.
Abstract: The removal of particles in water treatment plants through flocculation, sedimentation, and filtration depends on the design of each treatment process and physical characteristics of the raw water supply. Mathematical models, based on design variables for each process and the size distribution and density of the particles in the water, have been developed and linked to predict performance for a typical plant. The models for flocculation and sedimentation allow for broad particle sized distributions, but the filter model is limited to monodisperse suspensions. Quantitative predictions of the effects of changing values of the design variables on the performance of subsequent processes are evaluated. Filtrate concentration and head loss development are sensitive to changes in the velocity gradient during flocculation, the detention time in sedimentation, and the media size in filtration. Suspensions comprised primarily of inorganic particles require higher velocity gradients, longer settling times, and smaller filter media to produce acceptable finished water quality than suspensions containing amorphous precipitates.
TL;DR: In this article, the authors used the least square method to minimize the thermal conductivity, rate of energy production, heat transfer coefficient, and aeropermeability in a sanitary landfill.
Abstract: Flow parameters in governing differential equations include thermal conductivity, rate of energy production, heat transfer coefficient, and aeropermeabilities in solid waste. These are determined by the least squares using the simplex and finite element methods. The minimizing procedure requires measured values from the experiment such as temperatures in the solid waste, air influx from the leachate collection line at the bottom of the experimental vessel, and the surrounding temperature and pressure. Computed results show that thermal energy is produced in a semi-elliptic region of solid waste above the air inlet by aerobic biochemical reaction, and the vertical aeropermeability is ten times larger than the lateral one. The method applies to the design of sanitary landfill subjected to the natural convection of air.
TL;DR: The differences in design criteria between single residence onsite sewage disposal systems and large on-site systems were evaluated in this article. But the results indicated that most system failures are associated with impervious soil type, under-design and age of the system.
Abstract: The differences in design criteria between single residence on-site sewage disposal systems and large on-site systems were evaluated. The allowed loading for large systems on coarse sand is 45% higher, while the actual loading based on 1970 Census data may be 213% higher, as compared to household systems. Surveys in the state of Washington show that most system failures are associated with impervious soil type, underdesign and age of the system. Calculations indicate a serious under-reporting of the number of failures of both small and large on-site systems, thereby underestimating a major public-health risk.
TL;DR: In this article, a complete mathematical model reflecting the operation of a wastewater treatment plant including six units (primary settler, aerator, final settler and vacuum filter) is described, and the development of an efficient optimization method and the results from various runs are reported in a companion paper.
Abstract: The optimal design of a wastewater treatment plant involves two complementary aspects—the mathematical model and the optimization technique—both of which have to be equally developed. This was seldom the case in previous literature. A complete mathematical model is described reflecting the operation of a treatment plant including six units (primary settler, aerator, final settler, thickener, anaerobic digester, and vacuum filter). Although many of the basic relationships come from the literature, some new equations and concepts are proposed. Basically, these are based on the disaggregation of the waste load into four components (biodegradable and nonbiodegradable suspended solids, biodegradable dissolved solids, and biomass). The model equations described the evolution of each of these components during biological and physicochemical phenomena occuring in the treatment plant. The development of an efficient optimization method and the results from various runs are reported in a companion paper.
TL;DR: In this paper, it was shown that when oxygen is the oxidant, the precipitate is more likely to be very small crystals of lepidocrocite, γ\N-FeOOH, at low silica concentrations (LT7 mg/ at pH 7 with an iron concentration of 10 mg/1), but becomes amorphous at higher silica levels due to the adsorption of silica onto the growing crystals.
Abstract: Engineers have commonly described the iron precipitate in water treatment plants as ferric hydroxide, Fe (OH)\d3, but have also considered the possibility that in certain cases it might be ferrous carbonate. These were reasonable assumptions based on equilibrium constant data; however, neither Fe(OH)\d3 nor FeCO\d3 were ever actually proven to exist in water treatment plants. However, Fe(OH)\d3 is not a recognized crystalline mineral and recent investigations at Iowa State University found that FeCO\d3 unlikely to form in most treatment plants. Rather, when oxygen is the oxidant, the precipitate is more likely to be very small crystals of lepidocrocite, γ\N-FeOOH, at low silica concentrations (LT7 mg/ at pH 7 with an iron concentration of 10 mg/1), but becomes amorphous at higher silica concentrations due to the adsorption of silica onto the growing crystals. When a strong oxidant such as KMnO\d4 is used the precipitate has a much smaller pore structure and is amorphous.
TL;DR: In this article, a solution to the vehicle routing problem for refuse collection in large cities is presented, which accommodates real world constraints and employs a combined heuristic and computer approach, and the results of a case study in the Municipal Corporation of Greater Bombay brings out the efficacy of the algorithm in identifying the optimal refuse collection routes.
Abstract: A solution to the vehicle routing problem for refuse collection in large cities is presented. The algorithm accommodates real world constraints and employs a combined heuristic and computer approach. The results of a case study in the Municipal Corporation of Greater Bombay brings out the efficacy of the algorithm in identifying the optimal refuse collection routes.
TL;DR: In this paper, a study of the Fairmont Lakes in southern Minnesota conducted over a period of several years has produced extensive data on phosphorus budgets and time-series measurements of phosphorus concentrations which infer or prove that extensive release of phosphorus from the sediments occurs in midsummer.
Abstract: Phosphorus recycled from lake sediments is a most important nutrient source for midsummer algae blooms in very shallow northcentral lakes with depths from 2 to 7 meters. A study of the Fairmont Lakes in southern Minnesota conducted over a period of several years has produced extensive data on phosphorus budgets and time-series measurements of phosphorus concentrations which infer or prove that extensive release of phosphorus from the sediments occurs in midsummer. The in-situ evidence presented herein includes measurements of: (1) Phosphorus content in a major storm runoff event; (2) phosphorus depletion after spring snowmelt runoff; (3) phosphorus content in midsummer runoff compared to lake phosphorus content; (4) midsummer phosphorus stratification in the lake; and (5) relationship between temperature stratification and phosphorus stratification dynamics.
TL;DR: Agarwal et al. as discussed by the authors used greywater as the organic carbon source in the denitrification step of a nitrification-denitrification system, using greywater from a typical home contained abundant soluble carbon that biodegraded at the same rate as methanol, which appeared the most promising source of organic carbon for such a system.
Abstract: Nitrogen was removed from septic tank effluent in a nitrification-denitrification system, using greywater as the organic carbon source in the denitrification step. A preliminary study showed greywater from a typical home contained abundant soluble carbon that biodegraded at the same rate as methanol, which, until this study, appeared to be the most promising source of organic carbon for such a system. A second laboratory study used aerobic sand column reactors to nitrify unfiltered septic tank effluent. Greywater, settled sewage, and methanol were added prior to the denitrification step to determine their suitability as possible sources of organic carbon. Greywater removed 70 percent of the available nitrate, methanol removed 83 percent, and settled sewage removed less than 5 percent. A field demonstration model was then built. Greywater is an acceptable carbon source for denitrification.
TL;DR: In this article, a methodology is outlined that facilitates the development of models that can be used with increased confidence to predict urban stormwater pollutant washoff, which consists of testing several linear and linear transform multiple regression models for estimating pollutant loadings as a function of storm and basin characteristics, using measured data.
Abstract: It is not possible to derive general pollutant washoff functions, for either storm event total loadings or instantaneous fluxes, that contain a given set of independent variables and give reasonable results for most areas, even with calibration. Therefore, a methodology is outlined that facilitates the development of models that can be used with increased confidence to predict urban stormwater pollutant washoff. The methodology consists of testing several linear and linear transform multiple regression models for estimating pollutant washoff loadings as a function of storm and basin characteristics, using measured data. The best model can be chosen for each pollutant using the coefficient of determination (R²) and other criteria. This methodology eliminates the need to estimate both pollutant buildup and washoff.
TL;DR: In this article, an efficient optimization method is selected and adapted to the least-cost design of a wastewater treatment plant including six units (primary settler, aerator, final settler and vacuum filter).
Abstract: An efficient optimization method is selected and adapted to the least-cost design of a wastewater treatment plant including six units (primary settler, aerator, final settler, thickener, anaerobic digester, and vacuum filter). A previous companion paper presented a complete mathematical model describing the operation of the plant. The model, which turns out to be highly nonlinear, is reformulated as a geometric program, in order to take advantage of this quite flexible transcription mode. The generalized reduced gradient is then used and adapted for seeking the least-cost design of the plant. This method appears very efficient with regard to both computational results and cost minimization. The last part of the paper emphasizes and illustrates the recurrent use of the method in generating optimal solutions submitted to various practical and operational constraints, thus providing the designer with a efficient and wieldy tool for preliminary design.
TL;DR: A simplified design method is applied to the design of submerged filter and expanded bed biofilm reactors, and typical design parameters as well as kinetic and mass transfer coefficients are listed for several bacterial reactions including fermentation, aerobic respiration, nitrification and denitrification.
Abstract: A simplified design method is applied to the design of submerged filter and expanded bed biofilm reactors. Typical design parameters as well as kinetic and mass transfer coefficients are listed for several bacterial reactions including fermentation, aerobic respiration, nitrification and denitrification. The Monod maximum utilization rate appears to be smaller for biofilm reactors than for suspended growth reactors. However, biofilm reactors have much larger substrate removal rates per unit volume than suspended growth reactors due to the larger organism concentration. The expanded bed reactor has greater substrate removal rates than the submerged filter due to larger surface areas, less trapping of influent suspended solids, and smaller stagnant liquid layer depths.
TL;DR: In this paper, the authors derived from the principle of conservation of mass to represent the movement, decay, storage and treatment of stormwater runoff pollutants and dry weather wastewater flows through natural and engineered transport systems.
Abstract: Mathematical models are derived from the principle of conservation of mass to represent the movement, decay, storage and treatment of stormwater runoff pollutants and dry weather wastewater flows through natural and engineered transport systems. Hourly urban runoff flows and pollutant mass loadings and concentrations are generated by continuous hydrologic and water quality computer simulation models. The transient response of stormwater storage/treatment systems to variable forcing functions of flow and concentration is determined for completely mixed systems of constant and variable volumes and for one-dimensional advective systems with dispersion.