Mountain Scholar :: Browsing by Author "Carlson, Kenneth, advisor"

Browsing by Author "Carlson, Kenneth, advisor"

Now showing 1 - 20 of 23

Open Access
Anaerobic digestion comparison of manure leachate by high-rate anaerobic reactors
(Colorado State University. Libraries, 2013) Quiroz Arita, Carlos Enrique, author; Sharvelle, Sybil, advisor; Carlson, Kenneth, advisor; Davis, Jessica, committee member
A multi-stage anaerobic digester (MSAD) has been developed to obtain high organic leachate from high solids organic waste, thus high-rate anaerobic reactors can be fed by manure leachate, which can be obtained from a leachate bed reactor. Such configuration not only makes feasible the application of high-rate reactors to treat high solids content manure, but also the hydrolysis and the methanogenesis stages can be separated and controlled, individually. However, limited research is available on achieving ideal hydrodynamic conditions, inoculation, and performance of high-rate anaerobic reactors when manure leachate is used as the carbon source. Thus, this research is aimed not only to compare the performance of three different reactor configurations; the Upflow Anaerobic Sludge Blanket (UASB), fixed film, and a hybrid for processing manure leachate as a carbon source, but also to establish design criteria for such reactors including organic loading rates (OLRs) and hydraulic loading rates (HLRs). In the first part of this research, the influence of the hydraulic loading rates (HLR) in high-rate anaerobic reactors was investigated. The upflow anaerobic sludge blanket (UASB) reactor depicted a Morrill dispersion index (MDI) of 1.7, which is measured to evaluate the plug flow conditions of a reactor by approaching a value of 2 or less, at a HLR of 0.296 m3/m2-h. On the other hand, a MDI of 4 was observed when the HLR was increased to 0.829 m3/m2-h. The variation of the HLR had not notable impact MDI of the fixed-film and hybrid reactors; however, short circuits were observed at low HLR. Thus, the most suitable HLRs of such reactors were 10.632 m3/m2-h for the fixed-film reactor and 12.450 m3/m2-h for the hybrid reactor. To evaluate the performance of the UASB, fixed-film, and hybrid reactors to treat manure leachate, this research resulted in development of a method to inoculate such reactors in a single inoculation reactor. The accomplishment of the inoculation was measured by the redox potential, with values below -300 mV after seven days and remained steady until the day 33 with methane percentages in biogas ranging from 45% to 83%. Additionally, plastic media from the inoculation reactor was tested by the biochemical methane potential (BMP) assay, where inoculated organisms were confirmed to produce methane when supplied with glucose as a substrate. In spite that a hybrid anaerobic reactor inoculated with biomass obtained from an UASB reactor, plastic media, and manure leachate was successfully operated at an OLR of 4 kg/m3-d, when transferring the inoculated sludge and media to high-rate reactors, anaerobic digestion was not accomplished. The experiment setup did not support maintenance of anaerobic conditions. In addition, manifolds and open-channel flows were recommended in this research to enhance the reactors configurations. Moreover, results from hydrodynamic studies were applied to provide recomndations for future design parameter, which are included in this thesis.
Open Access
Analysis of Ball Corporation's Fairfield can manufacturing plant and the potential for industrial wastewater recycling
(Colorado State University. Libraries, 2016) Medearis, Timothy G., author; Carlson, Kenneth, advisor; Catton, Kimberly, committee member; Paschke, Mark, committee member
Ball Corporation is an American manufacturing company based in Broomfield, CO, which is best known for its work in the aluminum can and packaging industry. Ball Corporation has a vision of becoming a more sustainable and environmentally responsible manufacturer around the globe. With this in mind, Ball Corporation approached Colorado State University in the spring of 2015 with a request to conduct a study on the feasibility of conserving water use in its manufacturing plants. This study is the result of that initial request. Ball Corporation’s can manufacturing plant in Fairfield, California was studied in three different phases. The first phase involved a water audit of the Fairfield plant. The can washers at the plant produce 80% of the plants wastewater and were quickly identified as the primary opportunity for recycling. City of Fairfield municipal water quality was characterized and set as the target water quality for the treatment and recycling process. By comparing the effluent industrial wastewater quality to the city’s municipal water quality, macro parameters of most concern such as suspended solids, total organic carbon (TOC), and dissolved solids were determined. Effluent water from the plant averaged a turbidity of 23 NTUs, a conductivity of 6.46 mS/µm, and a TOC of 105 mg/L, while the municipal water quality reported 0.065 NTUs, 0.346 mS/µm, and 2 mg/L of TOC. The second phase of the study involved the actual bench scale testing of treatment processes at CSU. From June 2015 to March 2016, ten different grab samples of industrial wastewater from the Fairfield plant were sent to CSU. These samples were treated through coagulation, filtration, granular activated carbon, and reverse osmosis processes. The main results suggested that chemical coagulation was effective in removing some suspended solids, but not TOC. Electrocoagulation showed more promise in removing TOC. Ultrafiltration was very effective at eliminating suspended solids, but was unable to reduce TOC. TOC concentrations remained high after 0.05 µm ultrafiltration and even after 1 kDa filtration. Granular activated carbon (GAC) was able to reduce and completely remove 100% of TOC concentration with high enough doses. This reduction of TOC, was helpful in reverse osmosis. Reduction in TOC with GAC proved to increase flux across the membranes and produce a more pure permeate. After bench testing, a full treatment train of electrocoagulation, ultrafiltration, GAC, and reverse osmosis was proposed. This treatment train produced water quality with a turbidity of 0 NTU, conductivity of 0.32 mS/µm, and a TOC of 0 mg/L. This matches the municipal water quality goal. The third phase of the project involved a cost analysis of the proposed treatment train. WaterTectonics, a water treatment company out of Everett, WA, assisted CSU in providing pilot scale treatment options for Ball to consider. A 20 GPM treatment train consisting of electrocoagulation, ultrafiltration, GAC, and reverse osmosis was compared to an identical treatment train without the electrocoagulation step. The price difference for Ball to consider between the two pilots was $30,000.
Open Access
Analysis of produced water from three hydraulically fractured wells with different levels of recycled water
(Colorado State University. Libraries, 2016) McCormick, Brian E., author; Carlson, Kenneth, advisor; Sharvelle, Sybil, committee member; Stednick, John, committee member
With the growing use of hydraulic fracturing, injecting large amounts of water into oil and natural gas reservoirs to increase the quantity of oil and natural gas extracted, large amounts of water with low water quality are being created. This water has to be disposed of and many disposal methods have environmental concerns. One method of disposal is treating the water to remove the contaminants that have environmental concerns. Treatment of produced water for reuse, which will be identified as recycled water, as a fracturing fluid is becoming an increasingly important aspect of water management surrounding the unconventional oil and gas industry since the treatment does not have to be as robust as it would for disposal into surface water. Understanding variation in water quality due to fracturing fluid and produced water age are fundamental to choosing a data driven, water management approach. For these reasons, Noble Energy partnered with CSU to analyze the water quality differences between four wells with different levels of recycled water usage in a previous study. In that study, the findings showed a higher organic content of the produced water in the early period due to the presence of emulsified oil. The higher organic content of that produced water was the reason for using recycled water at more wells to determine if the higher organic content was repeatable at a different site. For this study, one well was 100 percent fresh water, another well was one part recycled water and five parts fresh water, and the last well was one part recycled waters and seven parts fresh water. Based on the data, the inorganic constituents vary more than the organic material. Inorganic variance being greater than organic makes sense due to the fact that the organic matter comes mainly from the fracturing fluid’s gel or slickwater component (Sick 2014), despite the organic variance seen in the previous study (White 2014). The inorganic matter mainly comes from the recycled water as seen from the ANOVA testing indicating significant difference between the wells, which is not treated to fresh water levels, and the data from the three wells shows a significantly higher value for the wells fractured with recycled water. A good illustration of the difference in the produced water quality that can be tied to the fracturing water quality is the TDS that was between four and six times higher in the fracturing fluid’s base fluid due to the use of recycled water. Of the inorganic constituents measured, aluminum, silicon, zinc, ammonium and sulfate were the only ones that did not show a statistically significant difference between the fresh water well and the recycled wells as indicated by a p value of 0.05 from an ANOVA test. None of the organic constituents showed significant statistical difference between the recycled wells and fresh water well, but they did vary over time indicating that the reactions and interactions with the geological formation affected the wells at a different rate. The wells did show a statistical difference both between the wells and over time, however, not in the way that was hypothesized as the organic material did not vary based on the wells. Total organic carbon (TOC), dissolved organic carbon (DOC), oil range organics (ORO), diesel range organics (DRO) and gasoline range organics (GRO) all had values 0.367, 0.758, 0.349, 0.768 and 0.707, respectively. The organics showed more significant difference over time with TOC, GRO, and ORO with p-values of 0.005, 0.012, and 0.029, respectively. However, the inorganic data did show significant difference between wells as well as over time. The inorganic constituents boron, barium, bromide, calcium, iron, potassium, magnesium, chlorine, strontium, sodium, and bicarbonate all had p-values of less than 0.01 except for chlorine which was 0.014. Potassium was the only constituent in that list that was not significantly different over time, but silicon and ammonium, which did not differ by well, did show significant difference over time. All of the inorganic constituents were very significantly different over time with no p-value over 0.01. The impact of this on the water management strategies shows that the understanding of the produced water quality and the factors that impact that is still largely unknown. More sampling and testing for well variability based on the ratio of recycled water in the fracturing fluid will allow more data and a better data driven management approach.
Open Access
Characterization and comparison of flowback/produced water of fresh water to recycled water stimulated wells and the subsequent evaluation of the influence of inorganic ions on fracturing fluid viscosity
(Colorado State University. Libraries, 2016) White, Shane A., author; Carlson, Kenneth, advisor; Catton, Kimberly, committee member; Sutton, Sally, committee member
As the Oil and Gas Industry begins to recycle flowback and produced waters, new challenges arise in using recycled water as a base fluid (fluid for hydrating gel) for future hydraulic fracturing operations. By understanding water qualities at all steps of the water life cycle in recycled operations, it is possible to improve treatment effectiveness and efficiency as well as make informed decisions on future fracturing fluid designs. This thesis contains two studies. The first study looks to determine water qualities, their differences and similarities, among multiple wells in the same Basin. These wells were fractured using a variety of techniques such as varied recycled to fresh water blends and fluid designs. The collection and water quality analysis of roughly 150 samples from seven wells on two different sites showed that there is little difference in water quality between wells fractured with recycled water (recycled wells) and wells fractured with fresh water (fresh wells). The study does not find noticeable differences in dissolved ionic concentrations between fresh and recycled wells. However, recycled wells located on the first site show emulsified oils in flowback. This can be observed with increased total organic carbon loadings of 12,170mg/l for day three flowback of one recycled well in comparison to 3,268mg/L for day three flowback of a fresh well. Treatment effectiveness was also correlated with emulsified oil concentrations and as their concentrations decreased, so did the coagulant dose required for optimum treatment. Spatial variation was observed between the two sites. Although the concentration of varying inorganics between the two locations was observable, temporal trends were consistent between wells. The second study provides data that can be used in decision making for future fracturing fluid design and development. By observing the effect individual ions and ion combinations have on fracturing fluid stability, operational limits were determined for two fracturing fluids employed by operators in the DJ Basin. Theoretical mechanisms of action were determined for the factors that influence fracturing fluid stability. Specific cations compete for crosslink sites on the gel polymer through shielding or by competitively complexing with active sites that the added crosslinker would normally complex with, resulting in a less stable fluid. Hydrogen bonds can sometimes form bonds at active sites and make a weak crosslink. At lower concentrations calcium and magnesium can replace these weaker crosslinks with stronger bonds, creating a more stable fluid.
Open Access
Characterization and treatment of produced water from Wattenberg oil and gas wells fractured with slickwater and gel fluids
(Colorado State University. Libraries, 2014) Sick, Bradley A., author; Carlson, Kenneth, advisor; Omur-Ozbek, Pinar, committee member; Bradley, Thomas, committee member
Treatment of produced water for reuse as a fracturing fluid is becoming an increasingly important aspect of water management surrounding the booming unconventional oil and gas industry. Understanding variation in water quality due to fracturing fluid and produced water age are fundamental to choosing an effective treatment strategy. This study involves the collection and analysis of produced water samples from three wells in the Wattenberg Field, located in northeast Colorado, over a 63-day study period (15 sampling events). One well was fractured with a cross-linked gel fluid, one with a slickwater fluid, and one with a hybrid of both fluids. Extensive water quality characterization was conducted on each sample to understand the impact of fracturing fluid type on temporal water quality trends. The greatest impact observed was that total organic carbon (TOC) concentrations were significantly higher in produced water samples from the wells fractured with the gel and hybrid fluids (943 to 1,735mg/L) compared to the well fractured with the slickwater fluid (222 to 440 mg/L). Total dissolved solids (TDS) concentrations, as well as many of the component inorganics that make up TDS, were fairly consistent among the three wells. TDS concentrations at each well increased with time from roughly 18,000 mg/L at day 1 to roughly 30,000 mg/L at day 63. Jar testing was conducted on collected samples to understand the variability in chemical coagulation/flocculation treatment due to type of fracturing fluid and well age. For the sampled wells, it was found that chemical coagulation can successfully reduce the turbidity of produced waters from wells fractured with both slickwater and gel fluids immediately after the start of production. The coagulant demand for produced waters from wells fractured with gel fluids was found to be roughly 25 to 300 % higher than that for wells fractured with slickwater fluids. The coagulant demand of produced water from each well was found to decrease with the age of the well. Additional laboratory characterization techniques were conducted on a subset of samples in order to better understand the makeup of organic compounds in produced water, including an analysis of the distribution of the volatile portion of solids, a TOC size analysis, and an analysis of organic subcategories. It was found that the majority of organic compounds in produced water samples are smaller than 0.2 µm, and that the relatively small portion that is larger than 1.5 µm contributes significantly to the predominantly volatile total suspended solids (TSS) load. Carbohydrates were found to be the largest contributor to the overall organic compound load in early produced waters from wells fractured with gel fluids; petroleum hydrocarbons were found to be the largest contributor from wells fractured with slickwater fluids. Chemical coagulation was found to reduce TOC concentrations by roughly 20%, independent of this difference in makeup.
Open Access
Chemical equilibrium modeling of phosphorus removal and recovery processes for advanced wastewater treatment
(Colorado State University. Libraries, 2018) Liu, Jinna, author; Carlson, Kenneth, advisor; Sharvelle, Sybil, committee member; Qian, Yaling, committee member
Phosphorus (P) is a fundamental element to all life. However, unmanaged phosphorus can create negative effects in the environment. Wastewater is a significant source of phosphorus and every day, thousands of wastewater treatment and recovery facilities treat billions of gallons of nutrient rich wastewater. During the treatment process, a large amount of sludge is produced and needs to be treated and disposed. The main process for sludge treatment is anaerobic digestion after which the solids are dewatered. However, the dewatered sludge liquor or centrate contains very high levels of nutrients (nitrogen and phosphorus) that needs to be removed from this water stream before being returned to the secondary treatment process. This recycle stream adds additional nutrients to the plant which affects treatment efficiencies and increases operating costs. Additionally, when the phosphorus, magnesium and ammonia are released in the digester, they combine and can create struvite, a mineral that can cause significant damage to equipment, pumps and piping. In many cases, nutrient removal technologies are added in the sludge and centrate treatment process. This study used chemical equilibrium modeling to examine phosphorus removal and recovery in the centrate from dewatered anaerobic digestion sludge. The chemical equilibrium of two P recovery technologies (CNP's AirPrex P-recovery process, Ostara's Pearl® P-recovery process) and one P removal method (precipitation with ferric) are modeled using MINTEQ to understand how the overall water quality changes and how this could impact downstream processes. AirPrex and Pearl® produced struvite, which can be used as green fertilizer, have several factors that influence the formation of product including pH, temperature and concentration of ions such as phosphorus, ammonia and magnesium. One of the important differences between the AirPrex and Pearl® technologies is that AirPrex is installed between the anaerobic digestion and dewatering processes, while Pearl® is installed after dewatering. Through the model work, AirPrex could reach 98% P removal and 70% P recovery at the optimal situation from the digested sludge. Pearl® could reach 97% P removal and 96% P recovery at the optimal situation from centrate. The P removal method with ferric chloride could reach almost 100% phosphorus removal.
Open Access
CLEAN WATER ACT ENVIRONMENTAL COMPLIANCE PROGRAM REVIEW OF TEN AIR FORCE BASES AND WATER QUALITY SURVEY
(Colorado State University. Libraries, 2024) Hoeffner, Jacob Kyle, author; Carlson, Kenneth, advisor; Carter, Ellison, committee member; Didier, John, committee member
This study includes two main components. First, environmental compliance program reviews (ECPRs) of ten AF bases investigated the permits, programs, and compliance records at an installation level. Due to the depth of the ECPRs, detailed performance metrics from EPA ECHO, EASIER, and OSD databases were integrated into the ECPRs findings. Second, a survey further investigated trends identified in the ECPRs across 25 participating installations. The relevant performance metrics were used to evaluate the effectiveness of water programs that participated in the survey. Systemic compliance risks in permit management, data management, and stormwater and wastewater infrastructure were identified.
Open Access
Development of an electrocoagulation based treatment train for produced water with high concentrations of organic matter
(Colorado State University. Libraries, 2016) Caschette, Richard Andrew, author; Carlson, Kenneth, advisor; Sharvelle, Sybil, committee member; Bradley, Tom, committee member
Well stimulation in the form of hydraulic fracturing has made unconventional oil and gas extraction economically feasible, significantly increasing the number of producing oil and gas wells in the United States in the last several decades. Both the hydraulic fracturing process and shale play development has created a large amount of oil and gas associated wastewater. Deep well injection or disposal wells are the preferred and most widely used method for managing produced water. This industry standard both eliminates valuable water resources from the hydrologic cycle and can be linked to the increasing frequency of seismic events in parts of the United States. This paper investigates water treatment processes in the context of beneficial reuse towards irrigation. Treating produced water on well pad locations followed by agricultural use within close proximity minimizes trucking costs and environmental impacts as well as recycles industrial wastewater back into the hydrologic cycle. High concentrations of salts and organic matter must be removed in addition to other contaminants (Benzene, Boron, Calcium, and Magnesium) from produced water collected from Noble Energy's Wells Ranch Central Processing Facility (CPF) before being applied towards a secondary use. Electrocoagulation coupled with a strong oxidant creates a more effective coagulation process prior to ultrafiltration, granular activated carbon and reverse osmosis processes. Organic matter removal and its potential for significant fouling of reverse osmosis membranes remains a major challenge as concentrations of total organic carbon in Noble Energy CPF produced water are typically around 1,500 mg/L after ultrafiltration. Four treated produced water effluent qualities generated in the CSU Environmental Engineering lab, in addition to freshwater were used to irrigate two non-food crops. Switchgrass and canola were arranged at the CSU greenhouse and watered using a drip irrigation system. The fate of regulated volatile organics and impact of salt accumulation are the primary parameters of interest for impaired water usage. This study is constructed to provide a baseline for the development of a larger scale pilot designed to treat produced water from an operator's storage tanks and used to irrigate nearby agricultural land. The concentration of dissolved organic carbon can be linked directly to the economic feasibility and operational challenges of treatment, both in the context of pretreatment and required maintenance for reverse osmosis. Although produced water from gel-based hydraulic fracturing in the Denver-Juleseburg can be very difficult to treat, beneficial reuse should be an important consideration for future shale play development in Colorado and other parts of the United States.
Open Access
Development of framework for predicting water production from oil and gas wells in Wattenberg field, Colorado
(Colorado State University. Libraries, 2012) Bai, Bing, author; Carlson, Kenneth, advisor; Grigg, Neil, committee member; Kreidenweis, Sonia, committee member
Water issues in the oil and gas industry have drawn attention from various stakeholders including the public, industry and environmental groups. With the increasing demand for energy, the number of oil and gas wells has increased greatly providing 60% of the energy in the United States. Besides the large volume of fresh water required for drilling and hydraulic fracturing, wastewater from the well can also lead to serious problems. The current approach for managing wastewater from oil and gas fields is deep well injection or evaporation both of which can potentially cause environmental issues. One of the best strategies to solve water issues from oil and gas operations is to reuse wastewater as drilling and fracturing water so the volume of fresh water required and wastewater disposed can be reduced. Information on both water quantity and quality are required when designing wastewater reuse treatment facilities. This study provides a framework for understanding water production trends from oil and gas wells in the Wattenberg field in Northern Colorado by analyzing historical data from Noble Energy Inc. The Arps equations were chosen for modeling water production from oil and gas wells. After studying 1,677 vertical and 32 horizontal wells in Wattenberg field, an exponential decline function was applied to model the produced water production of all the wells and the frac flowback water of horizontal wells. An Excel based 30-year water production prediction tool was developed based on the two protocols developed for vertical and horizontal wells in the Wattenberg field. Three case studies of different subsets of oil and gas wells were examined to illustrate the function of the tool. In addition, a comparison of exponential and harmonic functions was made in the third case study, and a significant difference was observed. The harmonic decline function predicts a less aggressive decline resulting in higher production volumes. It was concluded that in the absence of long term production data, the harmonic decline function should be used since the exponential decline function may underestimate the volume of produced water.
Open Access
Evaluation of cow peat as a plant growth media
(Colorado State University. Libraries, 2018) Thena Surendran, Amrish Nath, author; Sharvelle, Sybil, advisor; Carlson, Kenneth, advisor; Qian, Yaling, committee member
Almost 63% of non-CO2 greenhouse gases, mostly methane and nitrous oxide, are produced by the agricultural industry. As Livestock waste lagoons are designed to prevent the nutrient transport and treat manure, they are major contributors to the release of these non-CO2 greenhouse gases. They have to be controlled and one such way is to harness these gases by implementing anaerobic digestion. Anaerobic digestion of livestock waste has shown very good potential but, handling of digested solid end products require extensive management. One potential option is to recover fiber from the solid digestate to make a cow peat plant growth material. Peatlands are one of the most important natural ecosystems in the world which have key values for biodiversity conservation, climate regulation and support welfare, water regulation in drylands, acts as an enormous carbon sink and also an agricultural land. But overexploitation of peatlands has led to adverse effects on the environment. Peat mosses have well defined lignified cell structure as a soil material which makes them perfect media for plant growth. All these degradations and its effects have made peat extraction unsustainable and so search for alternatives have begun over the last decade. The fiber components of digested dairy manure (Cow Peat) have been evaluated by researchers as a suitable substitute for peat moss along with many other products such as biochar, rice husk, wheat straw, sewage waste, potato waste etc. Results have shown that the cow peat has similar physicochemical properties to peat moss and so, they have been widely used in the horticulture and floriculture industries as a replacement for peat moss. In this study, we assessed the potential to recover cow peat from a novel multi-stage anaerobic digester that processes high solids content manure. Edible crops were grown in the digestate and cow peat for the first time, as they have been already proven in the other industry such as the growth of perennial plants, strawberries, bedding plants etc. The study has been carried out in two trails without nutrient amendment. The first experiment was conducted with bean plants and 6 soil mixes with digested manure. The performance was compared with commercially available soil mixes including peat moss. The best performing soil mixes were utilized in a second experiment assessing two more plant types, beet, and lettuce. The results of both the experiments have revealed that digested manure (well composted digested manure solids) and fiber (component separated from manure solids by fractionation) component has produced plants with significantly similar (p > 0.05) shoot dry mass and root structure as commercially available plant media. The digested dairy fiber contains a significant amount of nutrients for the plant to germinate. Carbon/Nitrogen ratio was higher than recommended range and so may have had an adverse effect on pH and reducing the availability of micronutrients. Results demonstrate the potential for anaerobically digested fiber to replace peat moss as plant growth media providing growers with a local, renewable substitute for peat and a supplemental income for animal farm operators.
Open Access
Excess nutrients and cultural eutrophication of the Cache la Poudre River: a study of the occurrence and transport of phosphorus
(Colorado State University. Libraries, 2011) Goodwin, Stephen A., author; Carlson, Kenneth, advisor; Arabi, Mazdak, committee member; Keske, Catherine, committee member
Excess nutrients resulting in eutrophication of surface waters has become one of the greatest water quality challenges of our time. The development of an effective nutrient management strategy is essential to protecting surface water quality, public health, aquatic ecosystems and economic interests. The complexity of cultural eutrophication and the influence of nutrients, especially in streams and rivers, has delayed the development of an effective regulation and a nationwide management strategy. Variations in hydrologic conditions, geology and both urban and agricultural land use can dramatically influence phosphorus loads to receiving waters. Furthermore, several complex mechanism exist within a river or stream (e.g. the phosphate buffer, light availability, hydraulic retention time, phosphorus spiraling, etc.) that change the concentration and impact of nutrient concentrations and resulting eutrophication. Temporal and spatial variations result in changing and often imprecise threshold between healthy and unhealthy ecosystems. For this reason, it is important for policy makers to understand how the assimilative nutrient capacity of waterways varies with environmental, seasonal and loading conditions, and that it is not the same for every watershed or even within the same waterway. A one-size-fits all technology solution or a state-wide numeric standard that does not account for these variations is misguided and will result in costly upgrades with minimal improvements to water quality. The most efficient nutrient management method is one that best matches the nutrient load delivered with the maximum assimilative capacity of the receiving water. This study provides an in-depth analysis of the Cache la Poudre River Watershed in Northern Colorado over the course of a year to examine the influence of different sources, transport pathways and hydrologic regimes on phosphorus concentrations along an urban-agricultural gradient. An extensive and comprehensive design of sampling locations was used to best capture the anthropogenic influence (e.g. wastewater treatment plants, concentrated feeding animal operations, land uses) and transport pathways (e.g. irrigation ditches, overland transport, streams and rivers) of phosphorus within the watershed. Exploratory models were used to better understand the influence of geospatial variables on the occurrence and transport of phosphorus within the watershed. The influence of phosphorus from wastewater treatment plants (WWTPS) to the Cache la Poudre River was examined in detail. A mass-balance of the phosphorus load in the river and the effluent from WWTPs was used to best estimate the influence of WWTPs. Projections of the influence proposed regulations that reduce WWTP effluent concentrations were made as well as the resulting impact to the river and water quality. The role of sediment was investigated to better characterize and explain the temporal variations of phosphorus concentrations within this complex system. A brief economic analysis and associated improvements to water quality are discussed as well as effective management strategies in the Cache la Poudre River Watershed. The objective of the study is to aid in the development of an efficient and effective nutrient management strategy for the Cache la Poudre River Basin and other similar mixed land use watersheds, as well as providing a foundation for creating a decision support system for water quality analysis, monitoring and management.
Open Access
Methods to detect and analyse volatile organic carbons using low cost real-time sensors
(Colorado State University. Libraries, 2019) Gupta, Vatsal, author; Carlson, Kenneth, advisor; Carter, Ellison, committee member; Ham, Jay, committee member
VOCs are ubiquitous and can be found not only as vapors in the air but also as soil gas and dissolved in ground water. Vapor intrusion occurs when volatile organic compounds from contaminated soil or groundwater migrate upwards toward the ground surface and into overlying buildings or surfaces through gaps and cracks in the ground. In this thesis I have detailed several statistical analysis techniques and used these techniques on data that I obtained from active real-time soil gas and ground water quality monitoring sensors placed around an abandoned oil and gas well in Longmont, Colorado, to see if there were VOCs still being released from the site. The main goal of this study was to develop a more precise setup for real-time VOC release monitoring and help regulate fracking sites more efficiently and to analyze the data collected faster and more accurately. Another goal of this study was to bridge the gap between laboratory sampling and real-time on-site testing. From the results, we were able to analyze the movement of the contaminant plume using real time sensing and were also able to identify most of the constituents of the contaminants using in-situ data according to EPA method 18.
Open Access
Modeling of wastewater volume from unconventional oil and gas fields in Wattenberg field, and evaluation of low salinity waterflood enhanced oil recovery on shale wells
(Colorado State University. Libraries, 2016) Bai, Bing, author; Carlson, Kenneth, advisor; Catton, Kimberly, committee member; Stright, Lisa, committee member; Omur-Ozbek, Pinar, committee member
Reuse of wastewater from hydraulic fracturing (flowback and produced water) is a sustainable option for wastewater management practice in unconventional oil and gas fields. Reuse reduces fresh water demand but also lowers the environmental footprint by reducing the storage and transportation of both fresh and wastewater. A successful reuse practice requires a thorough understanding of both the quantity and quality of the wastewater, and more importantly, its potential impacts on well performance. In the first part of this study, wastewater production models were developed for horizontal shale wells in Wattenberg field .In addition, a solid characterization and distribution analysis on wells fractured with fresh and recycled water was performed to understand their impacts on wastewater quality. The second part of this study focuses on understanding the mechanisms of low salinity waterflood (LSF) in unconventional shale wells, and how oil recovery is impacted by the total dissolved solids (TDS) of the recycled brine. Results from the studies above are summarized in Chapter 4 through Chapter 7. A framework for water production prediction was developed in Chapter 4. Water production models were developed with Arps equation for horizontal wells from five fields in Wattenberg field. For a better data fitting and modeling, three time periods were defined: Frac flowback, transition period and produced water. The frac flowback period is the first one month after production starts, followed with 5 months of the transition period and, thereafter, produced water period. A correlation was found between water production volume and locations of wells,; thus, location is very important for estimating water production. Additionally, wells with low gas-oil-ratio (GOR) tend to have higher water recovery. In Chapter 5, sources of variability in flowback and produced water volumes from horizontal oil and gas wells were identified from external factors (time, location, type of frac fluids, wellbore length, and water source).. Horizontal wells in the Denver-Julesburg basin operated by Noble Energy were studied and results show that water production varies with time, location and wellbore length.. Additionally, production volume variation with fracturing fluid type and water source (fresh versus recycled) was explored. Results indicate that both of these variables should also be considered when developing a general model for water production. A guar-based frac fluid resulted in greater water production when compared to a cellulose derivative-based fluid. Finally, wells fractured with a fresh water based fluid had significantly greater produced water volume than geospatially-paired wells with a 1/7-recycled/fresh blend based fluid. Chapter 6 provides a qualitative and quantitative characterization of solids in frac flowback and produced water from five horizontal wells at two separate sites in the Wattenberg field of Northern Colorado. The difference in solids from wells fractured with fresh water and recycled water is compared, and their distribution and characterization are identified by particle size distribution measurement and X-ray photoelectron spectroscopy (XPS). Results show that particle were smaller and more uniform in produced water samples collected during the first week of production from the wells fractured with recycled water, suggesting that the recycled water was more compatible with the shale formation and wells fractured with recycled water tend to clean out faster. Chapter 7 investigates two of the fundamental mechanisms of LSF, clay swelling and diffused double layer (DDL) expansion. Both mechanisms are impacted by the salinity/total dissolved solids (TDS) concentration of the injection water. To test these mechanisms, clay swelling tests and real-time contact angle measurements were performed in this study. Spontaneous imbibition was also conducted, with Niobrara shale core plugs from Denver-Julesburg Basin, to compare oil recovery from low salinity and high salinity brine. Results show an increase in oil recovery when the TDS of brine falls between 400 and 10,000 mg/L. These results also indicate that LSF improves oil recovery from unconventional shale formation, and therefore, an optimal TDS concentration exists for highest oil recovery.
Open Access
Nitrate removal from groundwater using a reactive stream stabilization structure
(Colorado State University. Libraries, 2010) Mitchell, Christina M., author; Carlson, Kenneth, advisor; Watson, Chester, committee member; Stromberger, Mary, committee member
Riparian zones that remove nitrate (NO3-) from groundwater play a significant role in protecting and improving the quality of receiving surface waters. Denitrification, the microbial conversion of NO3 to gaseous forms of nitrogen (N ) is an important removal mechanism in these systems. For this process to occur there must be a supply of organic carbon (C ). High levels of organic C may be found in the subsurface of relatively undisturbed riparian zones. However, in areas where streambank erosion has resulted in the loss of riparian vegetation (C source) and organic-rich sediments, the amount of C available for denitrification is likely to be low. Vegetation may become established in these areas soon after the banks are stabilized using standard structural and/or bioengineering techniques. However, it will take time for organic C to accumulate in the soil. Thus, significant NO3 removal via denitrification will not be immediately observed following the completion of bank stabilization work. This study examined the potential for improving existing streambank stabilization designs to accelerate and maximize groundwater NO3 removal benefits. A simple, cost-effective structure, called the reactive stream stabilization (R S 2) structure, was designed for the purpose of this study. The RS2 structure combines a permeable reactive barrier composed of solid-phase organic C (sawdust) with a common bank stabilization technique (longitudinal peaked stone toe protection). A small field-scale RS2 structure and a control (no organic C amendment) were constructed along a stream in July 2003. The two systems were monitored from August to December 2003 and from M ay to September 2004. During the initial monitoring period, N O 3 removal in the reactive barrier averaged 93% (7.27 mg N L-1 along the upslope edge, versus 0.48 mg N L"' along the downslope edge). In comparison, NO3 removal in the control averaged 30% (12.3 mg N L-1 along the upslope edge, versus 8.65 mg N L-1 along the downslope edge). It was not possible to measure NO3 removal in the control the following spring and summer because the artificially generated plume of NO3 was not intercepted by the monitoring wells in the system. The plume was, however, intercepted by the wells located in the reactive barrier. Nitrate loss in the reactive barrier was high and averaged 97% (17.9 mg N L-1 along the upslope edge, versus 0.51 mg N L-1 along the downslope edge) during this period. The results of this study suggest that RS2 structures can enhance groundwater NO3 removal along streams. Additional field testing needs to be completed to verify these results, but it appears that the RS2 structure could be an effective tool for reducing NO3 loading to waterways.
Open Access
Optimizing water management in hydraulic fracturing
(Colorado State University. Libraries, 2016) Esmaeilirad, Nasim, author; Carlson, Kenneth, advisor; Omur-Ozbek, Pinar, committee member; Catton, Kimberly, committee member; Olsen, Daniel B., committee member
To view the abstract, please see the full text of the document.
Open Access
Pre-oxidation and adsorption with powdered activated carbon for taste and odor control and optimizing coagulation for dissolved organic carbon removal
(Colorado State University. Libraries, 2018) Vundala, Janardhan, author; Carlson, Kenneth, advisor; Catton, Kimberly, committee member; Bradley, Thomas, committee member
Geosmin and MIB (2-Methylisoborneol) are the two natural organic compounds produced by certain types of blue-green algae which cause taste and odor (T&O) issues in the sources of drinking water. Geosmin and MIB are not regulated by United States Environmental Protection Agency (USEPA) as they do not pose a health risk, but these two organic compounds seriously hinder the aesthetic appeal of finished drinking water due to the earthy or musty odor produced by them even at very lower concentrations (below 10 ng/L). Geosmin and MIB cannot be eliminated by conventional drinking water treatment processes, hence more advanced treatment techniques involving an adsorption agent like Powdered Activated Carbon (PAC) is necessary to remove these odorants and achieve concentration below the odor threshold. Boyd Lake Water Treatment Plant in Greeley region, gets it intake of raw water from two main drinking waters sources namely Boyd Lake and Lake Loveland. The plant has been experiencing T&O related issues mostly during the mid-summer to late autumn. This study was conducted for BLWTP in three phases to determine the optimal conditions to address the seasonal T&O issue and also help reduce the Dissolved Organic Carbon (DOC) content of the source waters efficiently with PAC. Preliminary testing was conducted on Lake Loveland and Boyd Lake water with an incremental alum dosage from 30 to 70 mg/L followed by three five minute stages of flocculation and 45 minutes settling time. Turbidity, TOC and DOC were measured before and after coagulant testing. The results indicated that Boyd Lake water was the hardest to treat, hence it was selected for further testing. In the initial phase of the study, about ten different PACs were tested in five batches, with Boyd Lake and plant mix water collected at different time periods. The results from the five batches were averaged and ranked based on the DOC reduction values. The results indicated that PAC Hydrodarco M was the cost and performance wise effective of the ten PACs tested. The second phase of the study involved testing four different PACs at four different contact times (15, 30, 45 and 60 minutes) with one constant dosage of 30mg/L for the kinetic study part. The results showed that maximum DOC removal was achieved at 45 minutes contact time. Similarly, the same four different PACs were tested with four PAC doses (10, 20, 30 and 40 mg/L) with one preset contact time of 45 minutes for the dosage study part. The results from these tests indicated that 30 mg/L was the optimal PAC dosage for maximum DOC removal. In the final phase, the raw water was initially treated with the various pre-oxidants with dosages of 1mg/L ClO2, 5 and 10 mg/L of NaMnO4 with a contact time of 60 seconds followed by PAC treatment with a dosage of 30 mg/L and a 45 minutes contact time. Test results revealed that pre-oxidants did not have a significant impact in DOC removal at any dosage levels. Additionally, two dosages 20 and 70 mg/L of coagulant alum were tested with pre-oxidant and PAC treated water. Detailed analysis was performed with coagulant alum in combination with pre-oxidant and PAC treated water. The results of the alum testing illustrated that a higher dosage of coagulant alum at 70 mg/L had a substantial effect on the DOC removal when compared to a lower dosage of 20 mg/L. Further, the results showed a two-fold increase in the DOC reduction at an alum dosage of 70 mg/L without the presence of any pre-oxidants.
Open Access
Precipitation and removal of ionic compounds from produced water: observed versus modeling results
(Colorado State University. Libraries, 2014) Yang, Xiaochen, author; Carlson, Kenneth, advisor; Catton, Kimberly, committee member; Bradley, Thomas, committee member
Produced water is generated during the hydraulic fracturing and drilling process, and is regarded as the largest byproduct associated with oil and gas industrial development. Samples of produced water from wells near Greeley, Colorado, were collected from February - July 2013. Commercial produced water treatment at the laboratory scale was conducted and the results compared to computer-based software modeling predictions. Different parameters, such as pH and temperature, are adjusted in order to test how these parameters could affect the treatment for produced water softening. The study shows that removal treatment performance could be related to pH adjustment of coagulation process, temperature and to the size of the filtration membrane. Comparison between different membrane filtration size (2.5 micron and 0.2 micron) apparently shows finer membrane (0.2 micron) improves the removal treatment performance. The results indicate that precipitation is not the limiter to divalent cation removal. During the research, OLI Chemical Analyst, the computer based modeling program, analyzed the precipitation performance of water samples under different temperature (-15 °C - 25 °C) and pH (9.0 - 10.2) conditions. The OLI Chemical Analyst shows that lower temperature could precipitate out different species. Sodium ions get separated (as NaAl(OH)2CO3, aluminum di-hydroxide carbonate) from the inflow when temperature is lower than 10°C, while other metal ions, such as calcium ions, barium ions, cannot get removed efficiently. However, the modeling results of pH adjustments demonstrate that lower pH would not obviously affect the scaling tendency of the target salts. The results show magnesium ions can only get removed when pH is higher than 11.0, the pH adjustment for softening can be optimized.
Open Access
Predictions of produced water quality and quantity for spatially-distributed wells in Niobrara formation
(Colorado State University. Libraries, 2012) Mingazetdinov, Ildus F., author; Carlson, Kenneth, advisor; Sutton, Sally, committee member; Catton, Kimberly, committee member
Two main problems facing the oil and gas industry are the availability of water for well construction and disposal of the produced water. Produced water is typically only treated for a limited number of constituents, and common disposal options have been deep well injection, evaporation or discharge to wastewater treatment plants. However, because of factors such as regulations, local water shortage, and bans on disposal via deep well injection, the future will require much of the produced water be treated and eventually recycled and reused for future field development or other beneficial uses. Multiple cost effective produced water treatment methods have been developed but limited research has been done to understand produced water production volumes and quality from oil and gas fields. Accurate predictions of produced water volumes and quality over a period of time can be used to optimize design and siting of water handling and treatment facilities in a spatially heterogeneous shale oil and gas field. The information can also be used to model availability of water resources and plan long term recycling strategies for augmenting regional surface water supplies. This study describes protocols to estimate and predict produced water quantity and quality from shale gas wells and applies these to a case study of Noble Energy Inc. wells in Yuma County, CO. Three different protocols of water production prediction were developed based on temporal and spatial variations of water quantity. Dissolution kinetics and geospatial data were used to develop a water quality prediction framework. A Microsoft Excel based tool, which uses a combination of water quantity and quality protocols, was developed to predict water production and total dissolved solids (TDS) from Noble Energy Inc. wells in Yuma County for different field development scenarios. A framework for interactive web based applications based on developed protocols is also provided. This study also provides a framework for development of GIS based web applications, which can provide an analysis platform for producers and consulting firms to predict water production and/or water quality, optimize location of treatment facilities, truck routings and help make other decisions related to water management. The study showed that using decline models to predict water production from shale gas fields will provide better long term predictions rather than using historical production average values. The case study and scenarios used for Noble Energy wells in Yuma County demonstrate that these prediction methods can be used in any other shale gas field by altering decline models and coefficients.
Open Access
Remediation of arsenic and persistent organic contaminants using enhanced in-situ methods
(Colorado State University. Libraries, 2008) Sullivan, Mary Elizabeth, author; Carlson, Kenneth, advisor; Pruden, Amy, advisor
The demand for inexpensive and reliable water treatment technologies continues to increase as the number of contaminants grows and their associated fate and transport mechanisms become more complex. Advances in public health have contributed to the implementation of more stringent drinking water standards for compounds such as arsenic. Furthermore, advances in analytical chemistry have contributed to the detection of previously immeasurable compounds including endocrine-disrupting compounds (EDCs), pharmaceuticals and personal care products (PPCPs), and other bioactive chemicals in wastewater effluents and surface waters around the world. This research examined the use of enhanced in-situ methods for the remediation of arsenic and several persistent organic contaminants. Unamended and amended electrokinetic remediation (ER) column studies conducted to determine the impact on arsenic revealed arsenic removal from the soil column due to the electrolysis of water and electromigration of the charged species. Column studies also examined the impact of amended aquifer recharge and recovery (ARR) treatment on persistent organic compounds. Water treatment residual-amended ARR columns were utilized to promote an environment capable of reducing flame retardants. The results indicated that the presence of water treatment residuals created a reducing environment and provided ideal adsorption sites and sources of organic matter in the form of leached carbon. Unamended and amended ER column studies were completed to examine the impact on two pharmaceuticals (sulfamethoxazole and carbamazepine) and three organophosphorus flame retardants (tris-(2-chloroethyl) phosphate, tris-(2-chloro-, 1-methylethyl)phosphate, and tris-(2-chloro-, 1-chloromethyl-ethylphophate). Results indicated that the highest removal results occurred in the significant redox zones of the ER column. Oxidizing conditions at the anode and reducing conditions at the cathode had significant impacts on the compounds' concentrations in the column's pore water. Lastly, critical characterization of the compounds' affinity for aqueous, colloidal, and solid phases was determined for the five organic compounds. These results, as well as sources of flame retardant contamination in the experimental design, was useful (and necessary) in interpreting the treatment results from the amended ARR and electrokinetic column studies.
Open Access
Simultaneous phosphorus and nitrogen removal using aluminum based water treatment residual
(Colorado State University. Libraries, 2011) Liang, Qian, author; Carlson, Kenneth, advisor; Davis, Jessica, committee member; Sharvelle, Sybil, committee member
In this study, an aluminum-based water treatment residual (Al-WTR) from a local water treatment facility was investigated for its capacity for phosphorus (P) and nitrogen (N) removal in wastewater. Characterization results indicated that Al-WTR had a high content of amorphous aluminum hydroxide, which is able to bond phosphorus in solution mainly via ligand exchange. Also, Al-WTR was found to be rich in bio-available carbon, which can facilitate biological denitrification for N removal. Batch equilibrium tests analyzed the P sorption parameters according to Langmuir and Freundlich isotherms. The results of the maximum sorption capacity were 4.498, 3.258 and 2.038 g/kg at pH values of 4, 7, and 9 respectively, indicating that P sorption was favored at lower pH conditions. However, the sorption capacity results may not reflect that in continuous-flow conditions. Al-WTR was shown to be a more effective sorbent for orthophosphate phosphorus (ortho-P) than total phosphorus (TP), but still had promising removals (greater than 90%) to both. Simultaneous P and N removal in wastewater was tested in column experiments in a continuous-flow mode. 95.9% removal of ortho-P and 90.0 % removal were achieved. Also, NO3- removal was highly efficient (99.6%). In sum, using Al-WTR as a P and N mitigation agent is a feasible and sustainable technology, and could be applied in P and N control practices in point-sources and non-point sources.