Showing papers in "Journal of the Environmental Engineering Division in 1974"

Fecal Bacterial Kinetics in Stabilization Ponds

Abstract: Fecal bacterial die-off is described by a first-order reaction assuming complete mixing, thus a series pond system is more efficient than a single pond of equal total volume. The death rate constant is reduced as the temperature falls and if thermal stratification takes place.

Simple Method for Predicting Dispersion in Streams

Abstract: A knowledge of the rate at which pollutants disperse in streams is essential to stream management It was the purpose of this investigation to develop a simple method for predicting longitudinal dispersion coefficients from mean flow parameters An analogy was used between the linear one-dimensional flow equation and the linear one-dimensional dispersion equation to define a relation between the solute dispersion coefficient and the flow dispersion coefficient The flow dispersion coefficient is calculated from mean flow parameters, thus allowing predictions of solute dispersion once the relation between the two is known Dispersion coefficients calculated by the simple method are compared with observed values for 18 streams that cover a wide range of flow conditions A standard error of estimate of 30% is indicated

Consumers Water Quality Index

Abstract: A water quality index based on physical, chemical, and biological parameters is proposed. The index is based on a geometric mean of transformed values of the parameters with a range of zero to one. The parameters of concern are temperature, nutrients, suspended solids, turbidity, coliform bacteria, dissolved oxygen, color, pH, grease, odor, and toxicity. The index is applied to some surface waters near Nashville, Tenn., and suggestions for further applications are presented.

Agricultural Waste Management

Abstract: The management of agricultural waste is amenable to techniques traditionally available to civil engineers. The problems with agricultural wastes, however, are different from those commonly encountered in the management of municipal waste. Serious problems have resulted when municipal waste technology has been transferred to the management of agricultural wastes without due consideration for the differences of generation characteristics and chemical characteristics of the waste materials. The management of agricultural wastes is described, using the example of animal manures. The management of animal manures requires the utilization of a system that somehow resolves the problems of separation of the manure from the animal, transport, storage or treatment, or both, and disposal. Treatment is for the purpose of making manure more amenable to cropland application or for the purpose of changing its physical and chemical characteristics so as to avoid application difficulties or nuisances attributable to application.

Effects of Temperature on Phytoplankton Growth

Abstract: Presently, efforts are being made to develop predictive mathematical models for water quality and food chains in lakes, rivers, and estuaries. Temperature is an important physical factor influencing the growth of planktonic plants. The effects of temperature on growth have not been investigated systematically for freshwater algae. This note reports the results of a literature review whose purpose was to define the effect of temperature on the growth of different phytoplankton groups. All surveyed data are listed in tabular form. A graphical interpretation of these data is presented that separates the effects into four phytoplankton taxa. This literature review provides a comprehensive data base which can be used to quantify phytoplanktonic growth responses to temperature. Quantification of these effects is essential for the construction of a multigroup phytoplankton model.

Waste Generation Models for Solid Waste Collection

Abstract: This paper describes the development and subsequent application of econometric models to generate disaggregate predictions of residential waste loads. Both time and waste load estimates were developed, and districting plans generated from sample data for the Town of Brookline, Mass. Included are descriptions of the character of the system, the waste generation models, and sample districting outputs.

Nitrification Rate in Biological Processes

Abstract: At least four reaction rate equations have been proposed to describe the process of nitrification. A more precise understanding of this reaction rate is needed to optimize the design of the process. The proposed equations which include the Monod, zero-order, first-order, and autocatalytic growth are reviewed. An experimental study is described which was designed to better understand the process reaction rate. The study involved a thin film biological reactor fed with a synthetic medium developed for the study of nitrification. This simple model was used to provide flexibility and control over such parameters as hydraulics, slime layer thickness, contact time, and wall growth problems. The rate determination was developed by varying both initial concentration and contact time. Results indicate that the reaction rate is zero-order between an initial ammonia nitrogen concentration of 2.5 mg/l - 673 mg/l.

Capital Cost Minimization of Drainage Networks

Abstract: This paper presents and compares three mathematical programming models for the optimization of drainage networks. The three models are based on two extensions of linear programming: separable-convex and mixed- integer programming. The first produces a continuous range of diameters while the second limits the solution to discrete commercially available sizes. It is shown that while the first can be formulated with pipes flowing full, the second must allow for partial flow. A solution which combines the use of both of these techniques can produce a minimum cost system with partially-full flows and commercially available diameters. This solution requires less computer time than those based strictly on mixed-integer programming. An example seven-link drainage network is designed by the three proposed methods and the results are reported in the paper.

Water Pollution and Associated Effects from Street Salting

Abstract: The bare pavement policy has resulted in a great increase in the use of deicing salts. They are more efficient and economical than abrasives. However, there is excessive application leading to environmental problems. Besides chemical melting, various methods for deicing exist. Some of these are stationary and mobile thermal melting units, alternate deicing compounds, snow adhesion reducing pavements, electromagnetic energy for ice shattering, and drainage systems designed to capture snowmelt for treatment or control. Salt storage facilities often become a major contributing source of local groundwater and surface water salt contamination. Coverage of salt piles is becoming chloride prevalent. High chloride concentration levels have been found in roadway runoff. The special additives in deicing salts may create more severe pollutional problems than the chloride salts.

Multivariate Techniques for Water Quality Analysis

Abstract: The objective of this study was to demonstrate the application of multivariate statistical techniques towards the understanding of variables affecting water quality. One of the major problems confronting an investigator in the application of statistical techniques to water quality data is missing observations. A simultaneous multiple regression method is presented in this paper for estimating missing observations in a data matrix. The major goals of using multivariate analysis are to facilitate interpretation and to prove hypotheses concerning the data. The techniques considered in this paper include principal components, canonical correlation, partial correlation, multivariate analysis of variance (MANOVA), and discriminant analysis. Examples are presented demonstrating the application of these methods.

Removal of Organic Matter by Activated Carbon Columns

Abstract: This study shows that the major organic fraction in activated sludge effluent that exhibited a high adsorption in activated carbon columns is a fulvic acid-like material with a molecular weight ranging from approximately 100 - 10,000. A high molecular compound with a molecular weight larger than 50,000 absorbed poorly in carbon columns. This compound consists of carbohydrates and proteins and resembles a humic acid-like compound. This fraction also enhances flocculation of bacteria and is found to prevent virus adsorption in diatomaceous earth filters coated with polyelectrolytes. Another fraction in activated sludge effluent that absorbed poorly in carbon columns consists of polar compounds, e.g., volatile free fatty acids with a molecular weight smaller than 100.

Sewer Line Design Based on Critical Shear Stress

Abstract: A design chart and a simple design procedure have been developed for applying the critical shear stress approach for the hydraulic design of self-cleaning circular sewers. Studies indicate that the possible region of deposition is limited to the lower relatively flat part of the sewer and the average boundary shear stress can be used safely as the basis of design for partially full flow. Suitable critical shear stresses for design uses are suggested. The conventional minimum velocity approach tends to either overdesign smaller sewers or underdesign larger sewers. A numerical example is included to illustrate the application of the chart and the procedure.

Temperature Effects on Microbial Growth in CSTR’S

Abstract: The effects of temperature upon the kinetics of a natural microbial culture were studied by growing the cells in continuous stirred tank reactors (CSTR). The maximum specific growth rate and specific decay rate were influenced by temperature in an Arrhenius fashion. The temperature characteristic for the specific decay rate was slightly larger than that for the maximum rate so that the ratio of the two was 1.1:1. As the temperature increased from 10 to 20°C, the true growth yield increased, but decreased with further increases to 40°C. The effect upon the saturation constant was just the opposite. The response of the observed yield to changes in temperature depends upon the growth condition imposed upon the organisms in a biological manner.

Least Cost Design of Branched Pipe Network System

Abstract: A new method for the direct least cost solution of pipe sizes of a branched pipe network of known geometry consisting of pumping station and network of pipes for known water consumptions incorporating various cost functions is being developed. The method developed gives optimum pumping head and total head loss in the network system and its optimum distribution among the various pipes of the network in seeking an overall least cost solution. The variation of the total cost with the total head loss in the system is studied. The method outlined herein is simple and can be efficiently used for the least cost design of branched water main systems only, with the help of a desk calculator. A systematic procedure of calculation has been described to illustrate the applicability of the technique using two sample problems.

Preliminary Model of Potomac Estuary Phytoplankton

Abstract: The upper 40-mile reach of the Potomac Estuary is modeled by a nonlinear, time variable representation of phytoplankton dynamics. Nitrogen and phosphorous recycling is included. Sensitivity analyses indicate that phytoplankton from tidal embayments can contribute as much as 40 μg/l to observed chlorophyll in the main channel. Loss of phosphorous to the sediments is significant. Flow transport through the estuary and the nutrients and phytoplankton associated with increasing river flow are particularly important. Simulations indicate that under nondrought flows and a 90% reduction of untreated nutrient loads, chlorophyll concentrations in the main channel may rise to 50 μg/l and to 70 μg/l in tidal embayments. These concentrations are above an objective of 25 μg/l, but are about 60% less than present values.

Effects of Deposit Resuspension on Settling Basin

Abstract: Scouring of deposits is one of the major factors in designing sedimentation basins for water and wastewater treatment systems. To express the degree of deposit resuspension a scouring parameter is introduced into a dispersion model. The parameter is taken into account in one of the boundary conditions of two-dimensional diffusion equation, which is simplified into a one-dimensional dispersion model. The scouring parameter is related to the longitudinal dispersion coefficient by a model experiment. On the basis of the mathematical expression developed, the existence of the optimum depth of a rectangular settling basin has been theoretically and has been experimentally verified.

Improving Mercury (II) Removal by Activated Carbon

Abstract: Research was performed to evaluate the effectiveness of mercury (II) removal from water by activated carbon with and without chemical aids. Batch tests, adsorption isotherms, and column runs were made on various systems. Treatment with activated carbon alone was most effective at low pH. Addition of a precipitating chelate ammonium 1-1 pyrrolidine dithiocarbamate improved capacity for mercury removal. Treatment of the activated carbon surface with carbon disulfide was also effective in increasing carbon capacity for mercury as compared to untreated carbon. It was possible to reduce influent mercury (II) concentrations from 3 mg/l to below 5 ppb with most of the systems tested.

Pitfalls in Parameter Estimation for Oxygen Transfer Data

Abstract: A consideration of methods employed to estimate the overall oxygen transfer coefficient and dissolved oxygen saturation value from nonsteady-state aeration tests is presented. The importance of good estimates of the dissolved oxygen saturation value is examined. Truncation of dissolved oxygen observations and its effect on oxygen transfer rate is revealed.

Systems Analysis and Solid Waste Planning

Abstract: Increasing waste generation, difficulties in labor-management relations, rising costs, and uncertain technology are only a few of the problems facing today's solid waste managers. A number of analytical tools, including management information systems, simulation, and mathematical models, are available and can be applied to the solution of these and related problems. This paper presents various system analysis approaches which have been used to analyze the solid waste management function and reports on the development of a management information system combined with a simulation model that has been implemented in a large metropolitan area. As a result of this project, the city made substantial changes in its solid waste application saving over $9,000,000 in 2 yr.

Oxygen Depletion Model for Cayuga Lake

Abstract: A one-dimensional oxygen depletion model was constructed for Cayuga Lake (upstate New York) for the period of summer stratification. A primary objective was to determine the relative importance of horizontal diffusion rates to planktonic and benthic respiration in the vertical. Terms in the one-dimensional diffusion equation account for sinking rate and consumption by respiration of algae, plankton, and benthos. A separate equation computes oxygen transport. The sensitivity of the model is tested with respect to the various parameters. Practical diffusion coefficients were obtained using a combination of methods. The results indicate that in Cayuga Lake all three of the depletion agents exert a large demand in the upper 30 m, the total uptake is small in the mid 70 m, but diffusion from this region into areas of the high demand is large, and the lowest 30 m is dominated by the benthic demand.

Site Evaluation and Design of Seepage Fields

Abstract: A reevaluation of previous work by others indicated that soil can absorb septic tank effluent indefinitely if the application rate is kept below a certain level, which is a function of soil permeability. This long-term acceptance rate is independent of whether the soil is continuously or intermittently flooded, and varies from approximately 0.3 gpd/sq ft (0.01 m/day) for clay loam to approximately 0.8 gpd/sq ft (0.03 m/day) for sand. A study of the ground-water flow pattern below a seepage field showed that it is, in many cases, the hydraulic conductivity of the ground surrounding the field, as determined by the external water table, soil permeability, and impervious strata, that controls the size of the field required. Reliable techniques for site evaluation of soil permeability, depth to water table, and depth to any impervious strata are presented, and a chart is given for designing a seepage field based on this information. Design examples are included.

Evaluation of Phosphorus Dynamics in a Watershed

Abstract: Phosphorus dynamics in a small river system have been measured to determine phosphorus transport mechanisms and correlation with hydrodynamic phenomena. Variation of chemical forms with flow conditions are related to point and diffuse sources and general equations derived. Mass balances are developed and diurnal changes are described.

Characterization of Mixing in Aerated Lagoons

Abstract: The macromixing characteristics of three mechanically aerated lagoons have been investigated using the residence time distribution approach. Four mathematical models capable of describing partially mixed behavior are fitted to the data. It is concluded that the macromixing regime is more dependent upon the lagoon geometrical parameters than upon operating parameters such as horsepower input. The pertinent correlation involved is \iD/(\IuL\N) = 3.10 x 10\u4 τ/\iL². in which τ is expressed in hours and \iL in feet. Based on this correlation, a suggested design procedure employing the axial dispersion model to account for partial mixing in an aerated lagoon is outlined. The unequally-sized completely mixed tanks-in-series model is particularly useful for making rapid hand calculations to analyze aerated lagoon performance.

Virus Removal by Diatomaceous Earth Filtration

Abstract: An investigation was made to determine the removal of bacteria viruses, T4 and MS2, by filtration through uncoated and polyelectrolyte coated diatomaceous earth (DE). Using a bench scale continuous-flow filtration apparatus, it was found that there was little, if any, removal of the viruses by uncoated filter media. However, filtration through diatomaceous earth coated with cationic polyelectrolyte resulted in significant virus removal. In studying the removal of viruses from a natural ground-water source, it was observed that organic matter in the ground water interfered with virus removal. The efficiency of virus removal, using both coated and uncoated DE, was also evaluated with respect to several physical and chemical variables, including pH, filtration rate, type of DE filter medium, and turbidity. All of these variables were found to affect the removal of viruses to some degree.

Optimization of Urban Air Monitoring Networks

Abstract: A method for optimally locating samplers in an ambient air monitoring network is presented. The criterion for site selection is based upon the overall effect of pollution dose on public health budgetary considerations and the Environmental Protection Agency’s implementation plan guidelines. A probability function, which attempts to rationally measure and compare the effects of pollution on population in each zone of the study area, is derived. The probability function is based upon the concept of population dosage product which is introduced and examined. A linear programming model, which located sampling stations based upon maximization of the probability of measuring significant values of the population dosage product, is utilized. The results of this method provide a decision maker with a measure of system effectiveness for various investment levels.

Control of Anaerobic Digestion Process

Abstract: The anaerobic digester is a common biological wastewater treatment process. A recently proposed fifth-order, nonlinear, dynamic model for the anaerobic digester has been shown to be qualitatively correct. Three methods of controlling the anaerobic digester are considered: base addition, organism recycle, and flow control. Feedback and feedforward controllers are designed for each of the control mechanisms, and a discrete adaptive predictive flow control algorithm is proposed. The control studies indicate that feedforward base addition control, in response to organic loading, is more effective and less expensive than feedback proportional base addition control. The predictive controller periodically computes optimum influent flow rate to the digester based on model response. This direct digital control method is adaptable to other wastewater treatment processes and offers flexible control objectives, allowing operational costs and quality of performance to be assigned weight factors, based on operational goals.

Household Waste Characterization

Abstract: In order to effectively study alternatives to the treatment and disposal of wastewaters from individual homes, a study was conducted to evaluate the qualitative and quantitative characteristics of wastes generated by both rural and urban households. A survey of a number of households, in concert with the analysis of current information available in the literature, provided data to establish guidelines characterizing individual wastewater events within the home. A simulated wastewater was subsequently developed for further research on treatment and disposal alternatives.

Water Quality Models Using the Box-Jenkins Method

Abstract: The Box-Jenkins method, a time-based technique for time series analysis, is shown to be successful in modeling chloride and dissolved oxygen data for the St. Clair River near Corunna, Ontario. This is thought to be the first application of the method to water quality data. The technique is demonstrated to be superior in this situation to either a frequency-based approach or a deterministic causative model. The description of the model building process includes the identification, estimation, and diagnostic checking stages. Forecasting and interpretation follow the derivation of the successful models. It is found that an autoregressive type of model best represents the chloride data, and a moving average process the dissolved oxygen following removal of nonstationarity. Similar causative mechanisms appear to influence June and December chloride and June dissolved oxygen.

Simulation of Water Quality in Tarawera River

Abstract: The Tarawera River, New Zealand, receives effluent from two paper and pulp mills and exhibits a very high rate of deoxygenation. Attempts have been made to predict water quality in the river using the Streeter-Phelps and various other first order models but none of these can successfully predict the observed concentrations of dissolved oxygen. Investigations of the biological activity in the river have indicated that biomass accumulates in the river sediments and that aerobic metabolism of these organisms on the organic matter in the overlying waters causes the high rate of deoxygenation. A stratified mathematical model is described which uses the Monod equations to predict the rates of growth of bacteria and protozoa in the river sediments. Chemical analyses of the mill effluent are used to formulate a theoretical multisubstrate system that predicts concentrations of dissolved oxygen successfully at varying rates of flow.

Statistical Evaluation of Reaeration Prediction Equations

Abstract: The object of much of the experimentation in atmospheric reaeration of natural streams is to develop models for predicting the reaeration coefficient, \ik\d2. These prediction equations are statistical correlations of the hydraulic variables and fluid properties thought to be important in affecting \ik\d2. Two previously reported models for predicting \ik\d2 are reevaluated in the light of these criteria. Although the models are useful for estimating \ik\d2, they do not adequately describe the variation in the observed data because their prediction error is significantly larger than the experimental error. Finally, two statistical models are used to predict \ik\d2 from data from a third, independent source. The prediction error varied between a factor of 2 - 3 about the predicted value. Comparison with values predicted by a model founded in the penetration theory for gas absorption was favorable. This suggests that theoretical models hold more promise than empirical correlations as a source for equations to predict \ik\d2.