Department of Chemical and Biological Engineering

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https://hdl.handle.net/10217/100365

These digital collections include theses, dissertations, and faculty publications from the Department of Chemical and Biological Engineering. Due to departmental name changes, materials from the following historical departments are also included here: Agricultural Engineering; Agricultural and Chemical Engineering; Chemical and Bioresource Engineering; Chemical Engineering.

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Now showing 1 - 20 of 87

Open Access
Ground water monitoring strategies to support community management of on-site home sewage disposal systems
(Colorado State University. Libraries, 1980) Nelson, James D., author; Ward, Robert C., advisor; McWhorter, D. B., committee member; Mielke, P. W., committee member; Hiller, R. L., committee member
Organizations which provide centralized management of on-site sewage disposal systems are currently evolving in many areas of the United States. At present, there is no routine feedback for management agencies regarding their efforts in preventing ground water contamination. Ground water monitoring is necessary to provide these agencies with the information they need to maintain ground water quality. This research is directed toward supplying monitoring strategies for that purpose. Ground water monitoring strategies presented herein were developed by combining deterministic and probabilistic approaches. The variables which need to be considered in such a monitoring program are discussed. Two types of monitoring are defined which need to be incorporated into an overall management plan. Inspection monitoring refers to the monitoring of individual systems to determine if they are exceeding their design discharge of pollutants to the ground water. Trend monitoring is defined as the monitoring which detects over time and space the cumulative effect of a management agencies pollution control efforts. Inspection monitoring strategies are developed in terms of the sampling frequencies necessary to obtain a specific probability of detecting system failure. A mathematical model describing the flow of pollutants through the leach field is developed for the purpose of evaluating sampling plans and a sensitivity analysis is performed to determine the effect of varying the parameters of the system and the input to the leach field. The discussion of trend monitoring strategies is based primarily on existing statistical theory. Sampling frequency is discussed in terms of the number of samples required to obtain an estimate of the mean of a water quality variable within specified confidence limits. The effect of spatial and serial correlation is also considered. Finally, a discussion of various sampling techniques applicable to ground water monitoring is presented.
Open Access
Optimizing salinity control strategies for the Upper Colorado River Basin
(Colorado State University. Libraries, 1981) Evans, Robert George, author
Salinity is the most serious water quality problem in the Colorado River Basin. The impact, felt largely in the Lower Basin, is acute because the basin is approaching conditions of full development and utilization of all available water resources. Current estimates indicate that each mg/1 increase in concentration at Imperial Dam results in $450,000 annual damages. Therefore, in order to offset salinity caused by the development of the vast energy supplies and to allow the seven Colorado River Basin states to fully utilize their allocation of Colorado River water, it is necessary to implement cost-effective salinity control programs in the basin. A simple multi-level nonlinear optimization procedure was utilized to formulate the most cost-effective array of salinity control strategies for the Upper Colorado River Basin. The incremental cost-effectiveness methodology qualitatively indicates the location and general type of alternatives to be implemented in a least cost basin-wide salinity control program. The results also qualitatively indicated the anticipated salt load reduction and expected annual costs of each salinity reduction increase for any preselected level of control. The analysis was limited to projects designated in PL 93-320. Costs and salinity contributions associated with various alternatives were generated using January, 1980, estimated conditions. Cost-effectiveness functions were developed for each of the major canals and laterals, the aggregate laterals under each canal, and an array of on-farm improvements for each agricultural project area. Similar functions were also developed for point sources such as Paradox Valley, Glenwood-Dotsero Springs and Crystal Geyser. Collection and desalination of agricultural return flows were also considered. Marginal cost analysis based on current damage estimates indicate that the optimal cost-effective salinity control program in the Upper Basin would cost about $30 million annually and remove about 1.2 million megagrams of salt per year. In addition, it was concluded that maintenance of the 1972 salinity levels at Imperial Dam cannot be cost-effectively achieved and should be allowed to rise by as much as 180 mg/1. Optimal salinity control programs are presented for the individual alternatives, for individual areas or projects, for the states of Colorado and Utah and the Upper Colorado River Basin. Sensitivity analysis showed that very large errors in costs and component salt loading would have to be evident to change the optimal salinity control strategy for the Upper Colorado River Basin.
Open Access
Design methodology for a large scale soil absorption bed for septic tank effluent
(Colorado State University. Libraries, 1984) Nettles, David L., author; Ward, Robert C., advisor; McWhorter, David B, advisor
In recent years there has been much interest expressed by small communities in alternatives to the conventional, centralized chemical-biological wastewater treatment system. One of the alternatives is a large scale soil absorption system. In these systems each home has its own septic tank with the tank effluent conveyed to a single, large absorption field. One of the problems encountered with large scale absorption fields is the buildup of a ground water mound beneath them to the point that insufficient treatment of the effluent is provided. In an attempt to alleviate this problem a model was developed for use in designing a large scale leachfield. The model developed was based on the Rao and Sarma (1981b) model of ground water mound buildup. The model was incorporated into a computer aided design (CAD) package consisting of three major divisions. These divisions were designed to: 1) determine the recharge area needed given the maximum acceptable ground water mound height buildup and the recharge rate, 2) determine the mound height given the recharge area and the recharge rate, and 3) determine the areal extent of the mound given the mound height, the recharge area, and the recharge rate. Testing indicates that the CAD package estimates either the recharge area or the the mound height for a constant recharge rate with reasonable accuracy (within 3% of the actual value). Also, testing indicates that the dosing procedure (applying large effluent volumes for short time periods once or twice daily) used on most large scale leachfields can be approximated by a constant recharge rate applying the same effluent volume per day. The CAD package appears to be well suited to the design of large scale leachfields. Further field testing is needed to establish this fact conclusively. The CAD package will be useful to persons concerned with on-site wastewater treatment for several reasons. 1) It estimates the leach- field area required based on the ground water mound buildup occuring beneath the leachfield. 2) The package can be used to estimate the height of the ground water mound beneath an existing leachfield. 3) The package can also be used to determine what effect the leachfield will have on other ground water influences, such as wells and streams. The CAD package is currently a useful tool that can aid in the design of large scale leachfields. However, the package could be improved by the incorporation of a dynamic recharge component to account for infiltration from precipitation events. Also, additional work on bacterial die-off and nitrogen conversion rates would improve the design by providing a better understanding of the unsaturated zone thickness required for wastewater treatment beneath the leachfield.
Open Access
Statistical analysis of water quality data affected by limits of detection
(Colorado State University. Libraries, 1986) Porter, Paul Steven, author; Ward, Robert C., advisor; Bell, Harry F., committee member; Loftis, Jim C., committee member; Skogerboe, Rod, committee member
Many water quality problems are related to substances which are present at concentrations too low to be measured precisely. Obtaining information from a monitoring system which produces many results near the fringes of analytical capabilities is not straightforward. This thesis is a discussion of the concerns one should have when statistically analyzing water quality data from such a system. Two general approaches are discussed. The traditional approach is to regard all measurements as precise or imprecise. Precise results are simply numerical responses, for which statistical analysis may lead to valid and sound monitoring information. Imprecise results are reported as "ND", or not detected, with criteria for reporting based on categories of measurement precision. Measurement error which leads to censoring is described. The impact of this error on the statistical characteristics of water quality data is illustrated using a model appropriate for analyte concentrations near the limit of detection. It is shown that the statistical properties of a set of measurements may not resemble the population from which samples were taken. This suggests the use of statistical methods which acknowledge observation error. Loss of information due to censoring is demonstrated and it is proposed that a numerical result be reported for all measurements. It is also suggested that an estimate of data precision accompany all results. This would permit the data user to censor at levels of uncertainty chosen by the user, rather than having information censored by the measurement process. When the number of results with significant observation error is small, or when data has been censored and no information is available regarding such error is available, statistical methods intended for censored data may appropriately be used. Such methods covering a variety of water quality problems are reviewed. Numerical examples of many methods are provided.
Open Access
Solute transport in variably saturated flow in porous media with dual porosity
(Colorado State University. Libraries, 1986) Lorentz, Simon A., author; McWhorter, David B., advisor; Ward, Robert C., committee member; Sanders, Thomas G., committee member
The transport of chemicals through solid waste disposal piles presents a potential source of surface and groundwater contamination. In an effort to determine the scope of the potential hazard, many laboratory tests have been devised and used on the waste materials. A prerequisite for such a test would be that it yield reproducible results. An added advantage, however, would be that the mechanisms of leachate generation in the test have some resemblance to those in the field. Therefore, on the premise that hydrodynamic conditions and solid-to-liquid ratios have a significant influence on the rate and quantities of chemical leached in situ, a standardized column leach test was developed for laboratory evaluation of oil shale solid wastes (Nazareth, 1984). In addition, an analytical model was developed to describe the effluent breakthrough curve (BTC). The physical mechanisms modelled were convection, dispersion and linear equilibrium adsorption in a partially saturated porous medium. The model predicted the results of leach tests on fine grained oil shale waste material. However, tests on large grained materials produced BTCs of a conservative chemical which were extremely asymmetric and exhibited and excessive tailing effect. This phenomenon could be caused by the diffusion of solute out of the retorted oil shale particles into the mobile water phase. The need for a model which included this additional process was realized. An approximate model and a solution for these processes are developed in this study (Model 1). The solution is compared with another approximate model in which the diffusion process is ignored (Model 3). This comparison shows that, for a certain combination of the physical properties of the medium, the BTC can be predicted without considering the diffusion process even though the material has a significant intra-particle volume. Model 1 predictions are compared with experimental BTX: results from column leach tests. The columns are packed with selected spherical particles which have a large intra-particle volume. Different sizes of particles are used and advection rates are varied in these idealized tests. The model is also used to predict the results of BTCs resulting from tests on a retorted oil shale packed at different bulk densities. The model successfully predicts the BTCs of leach tests where the unsaturated flew in the medium can be modelled by a Green-Ampt type wetting front. In other materials the model can be used to predict the data by calibrating the dispersion coefficient. In addition it is shown that for a specific combination of test parameters the intra-particle diffusion mechanism may be neglected even though the material has a large intra-particle volume.
Open Access
Extraction and fermentation of ensiled sweet sorghum
(Colorado State University. Libraries, 1987) Noah, Karl S., author; Linden, James C., advisor; Smith, Daniel, committee member; Dale, Bruce D., committee member
Sweet sorghum, variety Rio, was ensiled for 10 months prior to being subject to extraction studies using a pilot scale continuous countercurrent diffuser. An objective of the study was to see how control of liquid-solid ratio and diffusion temperature affected the recovery of sugars and organic acids from the ensiled sweet sorghum. Samples of the juice extracted from the sweet sorghum ensilage were fermented with Clostridium acetobutylicum and Saccharomyces uvarum to assure that no inhibitory or other detrimental substances were formed during the ensiling or extraction steps. As the liquid-solid ratio decreased, the diffusion juice component concentrations increased, but never to a level of fermentable sugars suitable for fermentation work. For a given change in ensilage sugar concentration over the length of the diffuser, it was found that not all of the liberated sugar was removed in the diffusion juice. Thus, even though greater than 90 percent of the components of the sweet sorghum were extracted, less than 90 percent of these components ended up in the diffusion juice. Therefore, the diffuser operated at unsteady state. Diffusion temperature had no effect on extraction efficiency. A model was applied to help predict diffuser performance. Only selected cases were found to provide satisfactory predictions. The organism best suited for fermentation of the concentrated ensiled sweet sorghum diffusion juice was C. acetobutylicum. The advantage of C. acetobutylicum was that in addition to sugars, it utilized lactic acid, the major fermentation product of ensiling. However, the C. acetobutylicum fermentations did not exhibit the acid break point; thus, small amounts of butanol were formed. No conclusions were possible pertaining to the formation of inhibitory substances during ensiling or extraction.
Open Access
Transport of copiotrophic bacteria in oligotrophic coarse soils: a Monte Carlo analysis
(Colorado State University. Libraries, 1987) Peterson, Thomas Charles, author; Ward, Robert C., advisor; Warner, James W., committee member; Hunt, H. William, committee member; Doxtader, Kenneth G., committee member
On-site wastewater treatment systems placed in coarse-grained, oligotrophic soils such as those typically found in the mountainous regions of the West are designed and installed with the assumption that most pathogenic microorganisms will not pass unaltered through an unsaturated zone located in the soil below each system. Studies have shown that 0.6 to 1.2 m of unsaturated soil below an on-site system drainfield is sufficient to remove most bacteria and viruses in most environments. Little is known of the transport of pathogenic, copiotrophic bacteria in coarse-grained soils below on-site drainfields placed in mountainous soil environments thought to be oligotrophic. A stochastic bacterial transport model was developed to analyze bacterial translocation in coarse-grained, mountainous soils beneath a hypothetical drainfield/soil interface. Specific model parameters were randomly generated using a procedure known to produce either a normal or log-normal distribution of random numbers. Numerous computer simulation runs were completed for hypothetical sandy and loamy sand soils subjected to a 10 year and 100 year rain storm. The resulting output was used to generate cumulative frequency distributions. Results from these simulations indicate that copiotrophic, enteric bacteria have the potential to travel great distances in oligotrophic, coarse-grained soils. The copiotrophic bacteria are likely to travel beyond the arbitrary 1.2 m of soil under conditions typically occurring in mountainous regions. The extent of bacterial transport and the bacterial concentration at any point in the soil is largely the result of the initial bacterial concentration, the impact of straining and clogging by the soil, and the bacterial die-off.
Open Access
Water-quality data analysis protocol development
(Colorado State University. Libraries, 1990) Harcum, Jonathan Brooks, author; Loftis, Jim C., advisor; Ward, Robert C., advisor; Hirsch, Robert M., committee member; Salas, Jose, committee member
Several agencies have developed networks to routinely monitor water quantity and quality in an attempt to assess society's influence on the environment, including the impacts of modern agriculture. Data from these networks are often plagued with attributes that inhibit analysis and interpretation. As more and more emphasis and public pressure is placed upon demonstrating environmental results, it is increasingly necessary that a consistent protocol for analyzing data from water quality monitoring networks be developed. Common data record attributes which inhibit data analysis include distribution applicability, variance heterogeneity, seasonality, serial correlation, extreme events, censoring, erroneous observations, small sample size, missing values, different sampling frequencies, multiple observations and measurement uncertainty. Each data record attribute is described in this study. In establishing a protocol to analyze water quality data, the handling of censored data and detection of trends in the presence of serial correlation and missing data are particularly difficult to quantify. This study focuses on these issues of protocol development. Seventeen procedures are evaluated for estimating the mean, median, standard deviation and interquartile range from data sets with singly and multiply censored observations. The results from this evaluation support previous investigations. In addition, the "no censoring” rule was found superior to methods which used censored observations for estimation of the mean, median and standard deviation. This study also compared the use of the Mann-Kendall tau test (and variations) for evaluating monotonic trends in water quality data. The Seasonal Kendall (Mann-Kendall) tau test should be used for data records with no serial correlation and five or less (ten or more) years of record. An ideal test for short data records which have serial correlation was not found in this study. The Seasonal Kendall tau test with serial correlation correction should be used for data sets of at least ten years of record and serial correlation. Furthermore, if monthly data sets have on the order of 40 to 50 percent missing values, monthly data should be collapsed to quarterly data by computing seasonal means or medians.
Open Access
Framework for development of data analysis protocols for groundwater quality monitoring systems
(Colorado State University. Libraries, 1992) Adkins, Nadine C., author; Ward, Robert C., advisor; Loftis, Jim C., committee member; Iyer, Hariharan, committee member; Bell, Harry F., committee member
Protocols for field sampling and laboratory sampling are used on a routine basis to produce accurate and precise water quality data. Efforts are now being focused on providing decision makers with the information they need from that data. Statistics is one method of extracting information from data. There are no widely accepted protocols for statistically analyzing groundwater quality data. Due to the wide variety of field conditions encountered in groundwater monitoring, a general protocol would be of limited use. What is needed is a set of guidelines for writing site specific data analysis protocols. A framework for developing data analysis protocols (DAPs) is presented in this thesis. The framework is essentially a "how-to" manual for protocol writers. It is designed to be concise, easy to use, and based on the current state-of-the-art. The focus of the framework is the analysis of groundwater quality data at hazardous waste facilities. Detailed background information is presented for the framework. The four main issues that are addressed include: information goals, data record attributes, and choice and interpretation of statistical results. There is a great deal of confusion in the water quality community regarding these issues. This thesis does not attempt to resolve that confusion. Instead, the goal was to sort out the areas of conflict and uncertainty, and present them in a clear manner. Recommendations are provided where possible. The framework was used to write a data analysis protocol for an IBM semiconductor manufacturing plant in Hopewell Junction, New York. The combination of flexibility in the basic framework and the availability of detailed background information was quite effective. It allowed the data analysis protocol to be site specific and scientifically defensible.
Open Access
Vegetation patterns along the Middle Fork of the Flathead River, Glacier National Park, Montana
(Colorado State University. Libraries, 1992) Wondzell, Mark, author; Ward, Robert C., advisor; Scott, Michael J., committee member; Jackson, William, committee member; Loftis, Jim C., committee member
Distribution of riparian vegetation on riverine floodplains is dictated, in part, by species' response to flood disturbance. Plant position can be related to frequency, intensity and duration of flooding, with species most tolerant of flooding occurring in lower discharge classes and those less tolerant occurring in higher discharge classes. Hydrologic conditions necessary to support distinct vegetation cover types and key indicator species along the Middle Fork of the Flathead River were identified and quantified. The natural flow regime of the Middle Fork was described in terms of the magnitude, frequency, and duration of discharge. Vegetation patterns were determined from species presence and relative abundance observed in transects located perpendicularly to the river and extending across the valley floor. A hydraulic model was used to compute the minimum discharge required to inundate each point along the transects. TWINSPAN (Hill 1979) analysis was used to identify four distinct cover types and several key indicator species. Direct gradient analysis was used to array cover types and key indicator species along a hydrologic gradient of inundation duration. Plots within the unvegetated or barren cover type were characterized by a minimum inundating discharge of 250 cubic feet per second (cfs) and a fraction of time inundated of 10 percent or greater. The willow cover type was defined by flows between 1000 and 15000 cfs (which correspond to recurrence intervals of < 1 - 2 years) and a fraction of time inundated of 0.45 to 25 percent. The cottonwood cover type was distinguished by flows ranging from 10 to 25 thousand cfs, a recurrence interval of 1 to 10 years, and a fraction of time inundated of 0.25 to 2 percent. Plots within the spruce cover type were characterized by flows greater than 25000 cfs, a recurrence interval of 10 years or more, and a fraction of time inundated of less than 0.35 percent. Key indicator species within a cover type (described in terms of density and percent absolute cover) were characterized by distinct hydrologic conditions representative of that particular cover type.
Open Access
Optimal design of groundwater quality monitoring networks
(Colorado State University. Libraries, 1992) Farr, Anne McCormack, author; Ward, Robert C., advisor; McWhorter, David, committee member; Salas, Jose, committee member; Bell, Harry, committee member
This research focuses on the optimal design of groundwater quality monitoring networks. The optimization technique developed allows for incorporation of both the model structure, data error, and model parameter uncertainty into the monitoring network design, with concurrent determination of sampling frequency and well locations. Particular emphasis has been placed on the use of stochastic models to describe groundwater quality data in order to incorporate both the deterministic and random behavior of groundwater quality in the model evaluation and monitoring network design processes. A protocol is developed for the evaluation of model applicability and the design of monitoring networks. This protocol was developed based on the results of a simulation study, with the developed protocol tested against field data; The simulation study provided a method of evaluating the performance of various model applicability tests and monitoring network designs against a known correct model. The performance of the protocol could therefore be evaluated for correct models with different magnitudes and types of error (additive and multiplicative normal and lognormal errors were considered), as well as for incorrect models with different magnitudes and types of error. The results of this research strengthen the importance of a detailed statistical evaluation of model applicability prior to the use of a model as a tool for describing groundwater quality behavior or prior to the design of monitoring networks. The model applicability evaluation should include the use of a variety of statistical tests to assess model applicability, and more importantly, should include the evaluation of the behavior of statistical tests compared to the theoretical expected behavior of the statistical tests for a correct model under conditions of varying sampling frequency, record length, and sampling density. In addition, the optimal monitoring network was found to be highly dependent on the sampling locations used to fit the model and to the monitoring locations identified to be considered for inclusion in the monitoring network.
Open Access
Gas concentration effects on plant cell cultures of Artemisia Annua
(Colorado State University. Libraries, 1993) Haigh, John R., author; Linden, James C., advisor; Murphy, Vincent G., committee member; Dunlop, Eric H., committee member; Nabors, Murray W., committee member
Many of the costly organic chemicals used by modern society are harvested from plants. A number of investigators have studied the use of plant cells in culture, rather than whole plants, as sources of some of the more valuable organic compounds. Before such processes can become a viable manufacturing option, a great deal more must be learned about the optimum conditions for growth and productivity of cells in culture. One aspect of this problem that has been relatively little studied is the effect of gaseous compounds on plant cell behavior. The most influential gases are believed to be oxygen, carbon dioxide and ethylene. One such organic compound of interest is the promising antimalarial artemisinin (known as "qing hao su" in China where it has been a folk remedy for centuries). It is produced in very low concentrations by Artemisia annua ("sweet wormwood"). The present author grew A. annua cells under a variety of dissolved gas conditions. Suspended cells were grown in tightly plugged flasks, in flasks under somewhat permeable conventional closures and under conditions of continuous headspace flushing with known gas mixtures. In the plugged culture tests, the usage rate of oxygen and production rates of carbon dioxide and ethylene per quantity of biomass were investigated. In the flushed headspace tests, cultures were exposed to various concentrations of the three key gases. The culture conditions were such that equilibrium between the culture liquid and gas headspace was assured. The growth rate of the cells and their production rates of artemisinin and related compounds were determined. These quantities were correlated as functions of the gas concentrations and compared with those exhibited by the conventional cultures.
Open Access
Advective-diffusive gaseous transport in porous media: the molecular diffusion regime
(Colorado State University. Libraries, 1993) Farr, John Merritt, author; McWhorter, David B., advisor; Weeks, Edwin P., 1936-, committee member; Sunada, Daniel K., committee member; Lenz, Terry G., committee member
Traditional mathematical models for advective-diffusive transport in porous media fail to represent important physical processes when fluid density depends on composition. Such is the case for gas mixtures comprised of species with differing molecular masses, such as found in the vadose zone near chlorinated hydrocarbon sources. To address problems of this nature, a more general advection-diffusion (A-D) model is presented, which is valid for porous media with permeabilities exceeding 10-10 cm2 (where Klinkenberg and Knudsen effects are negligible). The new mathematical model is derived by thermodynamic means, based on identifying the meaning of Darcy's advective reference velocity in terms of a weighted average of species drift velocities~ The resulting model has no additional parameters, and introduces no additional complexity or nonlinearity when compared to the traditional A-D model most commonly used in hydrology and environmental science. Because the form of traditional A-D models is retained, the new formulations fit readily into existing numerical simulators for the solution of subsurface transport problems. The new model is equivalent to the Dusty-Gas Model of Mason et al. (1967) for cases where the molecular diffusion regime prevails and pressure, temperature, and forced diffusion are negligible. Further support of the model is provided by hydrodynamic analysis, accounting for the diffusive-slip flux identified by Kramers and Kistemaker (1943). The new model is analytically compared to two existing A-D models, one from the hydrology literature, where Darcy's law is assumed to yield a mass-average velocity, and one from the chemical engineering literature, where Darcy's law is assumed to yield a mole-average velocity. Significant differences are shown to exist between the three transport models. The new model is shown to match closely with the experimental data of Evans et al. (1961a), while the existing A-D models are shown to fail in this regard.
Open Access
Information goals for a regional ground water quality monitoring system for the San Luis Valley
(Colorado State University. Libraries, 1994) Bagenstos, Dennis J., author; Ward, Robert C., advisor; Loftis, Jim C., advisor; Durnford, Deanna S., committee member; Smith, Freeman, committee member
The residents of the San Luis Valley of Colorado are dependent on ground water resources for agriculture, the economic base of the region, as well as most of their drinking water. The quality of this water, as a result of its extensive use, has become a concern in recent years. This concern has been expressed not only by local residents, but also the general public, as demonstrated by the numerous state and federal laws that address ground water quality issues. This concern tends to be addressed in a rather piecemeal fashion, particularly with regard to efforts to measure water quality in the San Luis Valley. Each concern and law appears to require its own separate monitoring program. Can the information needs generated by both local concerns and legal mandates be integrated into a more coherent set of information goals that would guide a unified monitoring program? What information would such a program need to produce? The purpose of this research was to develop a set of water quality "Integrated Information Goals" defined as the integration of those information needs extrapolated from the laws, regulations, and groups involved in water quality management in the Valley. In order to develop these information goals, the following tasks were defined: 1) Examine, through the review and identification of federal, state and local laws, regulations, implementing agencies, and concerned groups, the current structure of nonpoint source pollution management with respect to ground water quality in the San Luis Valley. 2) Based on the review in (1) above, define information goals for a monitoring design for the San Luis Valley. 3) Specify the Integrated Information Goals needed to support ground water quality management in the San Luis Valley. Upon completion of these tasks, five information goals were defined: 1. Baseline water quality of the shallow unconfined and the deep confined aquifers, 2. Source impacts to correlate water quality problems with land use practices, 3. Water table levels, 4. Water quality trend detection, 5. BMP analysis. Options for implementation of a monitoring system were also presented.
Open Access
Feed zone micromixing and its effect on continuous cultures of Saccharomyces cerevisiae
(Colorado State University. Libraries, 1995) Mondani, Paul, author; Loftis, J. C., advisor
Inadequate mixing is known to be a common problem in the scale-up of bioprocesses, often leading to decreases in yield and productivity. To investigate the role of nutrient dispersion in continuous cultures, growth medium was fed into a laminar flow section of a loop that recirculates broth from a laboratory scale bioreactor. The intensity of micromixing at the feed site could be controlled by varying the axial distance a static mixer was placed upstream of the site. The intensity of the turbulent wake shed by the mixer was quantified by laser Doppler velocimetry and the Bourne dye reaction. By decreasing the size of the smallest turbulent eddy in the feed zone, less of the population is exposed to regions of either inadequate or excessive substrate concentrations. Yield vs. dilution rate curves were obtained through various mixing and feeding strategies. Reduced mixing was shown to delay the onset of the Crabtree effect and therefore improve the bioreactor's productivity.
Open Access
Dependence of the formation factor on the unsaturated hydraulic properties of porous media
(Colorado State University. Libraries, 1995) Lorentz, Simon A., author; McWhorter, David B., advisor; Ward, Robert C., committee member; Durnford, Deanna, committee member; Warner, James W., committee member
Mathematical models of the hydraulic conductivity are used extensively to predict the movement of liquids in porous media. Included in these models is a description of the physics of flow as well as the nature of the conduits in which the liquids move through the medium. Since these flow channels comprise a complex network of pathways and have significantly varying geometries, the mathematical models developed assume a simplified arrangement and geometry of the flow channels which is termed the formation factor. The simplifications are derived from experimentally determined behavior of the porous media. These simplifications are generalized and used to describe the hydraulic conductivity of all porous media. The pore size distribution information is used to estimate the effective hydraulic radius of the medium. The effects of channel network and geometry are modelled by generalized relationships derived from experimentally determined formation factors or from unsaturated hydraulic conductivity observations. The dependence of the formation factor on the properties of porous media has not been studied. It is hypothesized that the effects of the channel network and geometry are a function of the pore size distribution or other properties of the porous medium and are thus material specific. It is proposed that a better understanding of the behavior of the hydraulics in porous media can be gained by determining the relationship between the channel geometry and the pore size distribution or other properties. Therefore, the specific purpose of this study is to: -Derive a simple mathematical model that describes both the unsaturated hydraulic conductivity as well as the formation factor that represents the channel geometry; -Determine the pore size distribution and other porous media properties, the formation factors and hydraulic conductivities at various saturations by laboratory experiments on two soils with significantly different pore size distributions; -Test the model’s capability to predict both the formation factor and hydraulic conductivity of the soils so that conclusions can be made about the dependency of the channel geometry or formation factor on the pores size properties of the media; and -Develop a generalized relationship for the formation factor using porous media properties. The results of the study indicate that the formation factor increases with increasing pore size distribution index. It also is apparent, however, that the pore formation factor is not uniquely dependant on the pore size distribution index and that the relative size of the pores also may contribute to the dependency of the formation factor on the unsaturated properties of the porous media. In addition, it has been determined that the dynamic flow process is influenced by the formation factor to a greater degree than is the static ion diffusion process.
Open Access
Data analysis reporting protocols for ground water quality monitoring in the San Luis Valley, Colorado
(Colorado State University. Libraries, 1995) Goetz, Lacey R., author; Ward, Robert C., advisor; Loftis, Jim, committee member; Cardon, Grant, committee member
This thesis investigates the concept of designing a regional, long term, ground water quality information system that complies with all of the laws and regulations applicable and provides information needed by water resource managers, water users, and the general public for the upper, unconfined aquifer in the San Luis Valley, Colorado. A set of “Integrated Information Goals” was developed by Bagenstos (1994) and provides the foundation for this thesis. The laws forming the bases of the information goals are examined further to provide a rationale for translating the information goals into quantifiable statements. These statements are subsequently examined to determine if statistical analysis is required and to develop statistical goals where needed. Statistical methods for handling the data to meet the statistical goals are suggested. Via this exercise, monitoring activities and subsequent data analyses are directly linked to the information goals by the data analysis protocols developed. Reports currently generated that include information about the quality of the water in the upper aquifer of the San Luis Valley are reviewed, along with EPA’s requirements for reporting ground water quality and recommendations for preparing reports presented by the Intergovernmental Task Force on Monitoring. A report format is suggested and samples of graphics for quick and easy conveyance of water quality information sought are provided. This exercise provides the people of the San Luis Valley with a method for ensuring the monitoring system is productive because the final product is defined prior to implementation of the monitoring system. The purpose of this thesis is to demonstrate how to link monitoring activities to legislation, ensuring the accountability of monitoring systems, and providing scientifically defensible information that meets the needs of resource managers and water users.
Open Access
Taxol productivity and physiological relationships in suspension cultures of Taxus Cuspidata
(Colorado State University. Libraries, 1995) Mirjalili, Noushin, author; Linden, Jim C., advisor; Reardon, Kennete F., committee member
Taxol, an extractive of the Pacific yew, is a plant secondary metabolite that has demonstrated anticancer activity. In an effort to prevent depletion of Pacific yew population and to obtain adequate supplies of taxol, alternative methods of production are being sought. The goal of this research was to produce taxol in sufficient quantities for clinical use by manipulating engineering parameters that affect production of secondary metabolites in plant cell culture systems. Production of taxol in suspension cultures of Taxus cuspidata in shake flasks exposed to different concentrations and combinations of oxygen, carbon dioxide, and ethylene was investigated. The effect of each gas on cell growth and taxol production was studied using several sets of factorial design experiments. Low head space oxygen con-centration (10% v/v) promoted production of taxol prior to day 14. High carbon dioxide concentration (10% v/v) inhibited taxol production. Taxol concentration increased as ethylene concentration was increased to 5 ppm; it leveled at 10 ppm ethylene. The utilization patterns of sugars were dependent on headspace gas composition. Average calcium uptake rates into the cultured cells decreased and average phosphate uptake rates increased as the ethylene concentration was in-creased from 0 to 10 ppm. Ethylene concentration at 50 ppm had an inhibitory effect on taxol production but not on phosphate uptake rate, suggesting independent regulation of taxol biosynthesis and physiological functions of the cell. The most effective gas mixture composition tested in terms of taxol production—10% (v/v) oxygen, 0.5% (v/v) carbon dioxide, and 5 ppm ethylene—is thought to be related to regulation of gene transcription. To stimulate taxol production, suspension cultures of Taxus cuspidata were challenged with various concentrations and combinations of methyl jasmonate (an elicitor derived from jasmonic acid) and ethylene. Taxol productivity increased 19-fold compared to the basal level when Taxus cuspidata suspension cultures were exposed to 5 ppm ethylene and 10 μM methyl jasmonate. The induction of taxol biosynthesis occurred within 51 hours after elicitation. Simple induction models were proposed to explain the action and effects of both ethylene and methyl jasmonate with regard to receptor binding and transcription regulation in plants.
Open Access
Biodegradation of dinitrotoluene by Pseudomonas PR7 in a fluidized bed bioreactor
(Colorado State University. Libraries, 1997) Whitty, Katherine Keesling, author; Reardon, Kenneth F., advisor; Murphy, Vincent G., committee member; Linden, James C., committee member
2,4-Dinitrotoluene (DNT) has been listed as a priority pollutant by the U. S. EPA. It is a waste product in the production of 2,4,6- trinitrotoluene (TNT) and toluene diisocyanate. Pseudomonas PR7 is able to completely degrade DNT via an oxidative pathway. Batch suspended-cell experiments were performed in order to determine the maximum specific growth rate Pmax/ and the Monod half-saturation constant. Ks. Parameter values of μmax = 0.1 h-1 and Ks = 14 mg/L were obtained by fitting experimental data to the Monod model. Immobilized-cell experiments in a fluidized-bed bioreactor (FBB) were performed in order to determine volumetric DNT degradation rate v for the biodegradation of DNT. A fluidized-bed bioreactor was chosen for study because (1) immobilization of cells onto particles allows for greater cell retention, and (2) fluidization of particles allows for mixing within the reactor. Greater cell retention allows for higher flow rates of liquid through the reactor and adequate mixing can alleviate the problem of low oxygen availability and other accumulation or depletion problems which occur in packed beds. Fluidization of immobilized cells in the FBB was achieved by the upflow of air and liquid. Data from residence time distribution (RTD) analysis of the FBB suggests that it behaves as a stirred tank reactor with small plug-flow regions and dead zones. The fluidized-bed bioreactor performance was compared with that of suspended-cell experiments and packed-bed experiments through direct comparison of DNT loading versus degradation rates. It was found that the fluidized-bed bioreactor performed as well as a previously reported system consisting of a packed-bed column in series with a stirred-tank reactor in one experiment using diatomaceous earth particles as the immobilization medium. The FBB did not perform as well as the packed-bed system in subsequent experiments using polycarbonate particles.
Open Access
Initial development of a multistage cancer model based on Syrian hamster embryo (SHE) cell transformation studies
(Colorado State University. Libraries, 1999) Liao, Kai-Hsin, author; Yang, Raymond Shih-hsien, 1940-, advisor; Reardon, Kenneth F., advisor; Murphy, V. A., committee member
To better incorporate biologic information into quantitative cancer modeling, the two-stage MVK (Moolgavkar-Venzon-Knudson) model has been modified for use with SHE cell neoplastic progression. Conceptually, five phenotypic stages are included in this model: normal cells can either become senescent or mutate into immortal cells followed by anchorage-independent growth and tumorigenic stages. Cells in each stage have distinct division, death and mutation rates, and mutation is assumed to occur during cell division. Model development and related experiments were focused on studying the abilities of lead, arsenic, chromium, and a mixture of these three metals to induce progression of SHE cells from one phenotype to the next. Cell division and death rates were assessed using flow cytometric analysis for inclusion in the model. Cell division rates were measured using bromodeoxyuridine (BrdU) incorporation with propidium iodide staining, which allows for the calculation of potential doubling time, a measure of cell cycle time that takes growth fraction, but not cell loss, into account. Potential doubling times of normal SHE cells ranged from 12 to 59 hours, depending on the degree of confluence of cell cultures. Cell death was measured by a flow cytometry method based on propidium iodide staining specifically related to membrane damage. The mean cell death rate is approximately equal to 1 % of the average value of division rates. The individual metals and their mixture did not induce immortalization or further mutations of SHE cells in our laboratory following a 2-day exposure. However, the growth of SHE cells was inhibited by 5.4 μM of arsenic, with cells becoming senescent after only 16 population doublings; whereas, normal cells and cells exposed to lower arsenic concentrations lasted for at least 30 population doublings. The model developed in our laboratory successfully predicted the growth of normal cells. The cell senescence rates under the impact of arsenic exposure were also calculated. Mechanisms responsible for induction of cellular senescence in SHE cells exposed to arsenic may be involved in the apparent inability of arsenic to induce neoplasia in experimental animals.