Mountain Scholar :: Browsing by Author "Sharvelle, Sybil, committee member"

Browsing by Author "Sharvelle, Sybil, committee member"

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A data-driven characterization of municipal water uses in the contiguous United States of America
(Colorado State University. Libraries, 2024) Chinnasamy, Cibi Vishnu, author; Arabi, Mazdak, advisor; Sharvelle, Sybil, committee member; Warziniack, Travis, committee member; Goemans, Christopher, committee member
Municipal water systems in the United States (U.S.) are facing increasing challenges due to changing urban population dynamics and socio-economic conditions as well as from the impacts of weather extremities on water availability and quality. These challenges pose a serious risk to the municipal water providers by hindering their ability to continue providing safe drinking water to residents while also securing adequate supply for economic growth. A data-driven approach has been developed in this study to characterize the trends, patterns, and urban scaling relationships in municipal water consumption across the Contiguous United States. Then using sophisticated and robust statistical methods, water consumption patterns are modeled, identifying key climatic, socio-economic, and regional factors. The first chapter of this data-driven study looked at municipal water uses of 126 cities and towns across the U.S. from 2005 to 2017, analyzing the temporal trends and spatial patterns in water consumption and identifying the influencing factors. Water usage in gallons per person per day, ratio of commercial, industrial, and institutional (CII) to Residential water use, and percent outdoor water consumption were statistically calculated using aggregated monthly and annual water use data. The end goal was to statistically relate the variations in CII to Residential water use ratio across the municipalities with their local climatic, socio-economic, and regional factors. The results indicate an overall decreasing trend in municipal water use, 2.6 gallons per person annually, with greater reductions achieved in the residential sector. Both Residential and CII water use exhibit significant seasonality over an average year. Large cities, particularly in the southern and western parts of the U.S. with arid climates, had the highest demand for water but also showed the largest annual reductions in their per capita water consumption. This study also revealed that outdoor water use varied significantly from 3 to 64 percent of the Total water consumption across the U.S., and it was highest in smaller cities in the western and arid regions. Factors such as April precipitation, annual vapor pressure deficit, number of employees in the manufacturing sector, total percentage of houses built before 1950, and total percentage of single-family houses explain much of the variation in CII to Residential water use ratio across the CONUS. The second chapter leverages high-resolution, smart-metered water use data from over 900 single-family households in Arizona for the water year 2021. This part of the study characterizes the determinants or drivers of water consumption patterns, specifically in single-family households, and presents a framework of statistical methods for analyzing smart-metered water consumption data in future research. A novel approach was developed to characterize household appliance efficiency levels using clustering techniques on 5-second interval data. Integrating water consumption data with detailed spatial information of the household and building characteristics, along with local climatic factors, yielded a robust mixed-effects model that captured the variations in household water uses with high accuracy at a monthly time-step. Local air temperature, household occupancy level, presence of a swimming pool, the year the household was built, and the efficiency of indoor appliances and irrigation systems were exhibited to be the key factors influencing variations in household water use. The third and fourth chapter of this study reanalyzed the water consumption data of those 126 municipalities. The third chapter dwelled into the estimation of the state of water consumption efficiencies or economics of scale in the municipal water systems using an econometrics framework called urban scaling theory. A parsimonious mixed-effects model that combined the effects of socio-economic, built environment, and regional factors, such as climate zones and water use type, was developed to model annual water uses. The results confirm efficiencies in water systems as cities grow and become denser, with CII water use category showing the highest efficiency gains followed by the Residential and Total water use categories. A key finding is the estimation of the unique variations in water use efficiency patterns across the U.S. These variations are influenced by factors such as population, housing characteristics, the combined effects of climate type and geographical location of the cities, and the type of water use category (Residential or CII) that dominates in each city. The fourth or the final chapter synthesizes the lessons learned previously about the drivers of municipal water uses and explores the development of a model for predicting monthly water consumption patterns using machine learning algorithms. These algorithms demonstrated improved capabilities in predicting the Total monthly water use more accurately than the previous modeling efforts, also controlling for factors with multi-collinearity. Climatic variables (like precipitation and vapor pressure deficit), socio-economic and built environment variables (such as income level and housing characteristics), and regional factors (including climate type and water use type dominance in a city), were confirmed by the machine learning algorithms to strongly influence and cause variations in the municipal water consumption patterns. Overall, this study showcases the power of data-driven approaches to effectively understand the nuances in municipal water uses. Integration of the lessons learned and the statistical frameworks used in this study can empower water utilities and city planners to manage municipal water demands with greater resiliency and efficiency.
Open Access
A facilitated process and online toolset to analyze complex systems and coordinate active watershed development and transformation
(Colorado State University. Libraries, 2014) Herzog, Margaret T., author; Labadie, John W., advisor; Grigg, Neil S., advisor; Sharvelle, Sybil, committee member; Lacy, Michael G., committee member; Clayshulte, Russell N., committee member
Integrated Water Resources Management (IWRM) coordinates public, private, and nonprofit sectors in strategic resource development, while emphasizing holistic environmental protection. Without more integrated efforts, adverse human affects to water, other natural resources, and ecosystems services may worsen and cause more unintended cross-scale effects. Meanwhile, fragmented jurisdictional controls and competing demands continue to create new obstacles to shared solutions. Lack of coordination may accentuate negative impacts of extreme events, over-extraction, and other, often unrecognized threats to social-ecological systems integrity. To contend with these challenges, a research-based, facilitated process was used to design an online toolset to analyze complex systems more holistically, while exploring more ways to coordinate joint efforts. Although the focus of the research was the watershed scale, different scales of social-ecological problems may be amenable to this approach. The process builds on an adaptive co-management (ACM) framework. ACM promotes systems-wide, incremental improvements through cooperative action and reflection about complex issues affecting social-ecological systems at nested and overlapping scales. The resulting ACM Decision Support System (DSS) process may help reduce fragmentation in both habitat and social structure by recognizing and encouraging complex systems reintegration and reorganization to improve outcomes. The ACM DSS process incorporates resilience practice techniques to anticipate risks by monitoring drivers and thresholds and to build coordinated coping strategies. The Bear Creek Watershed Association (BCWA) served as a case study in nutrient management, which focused on understanding and mitigating the complex causes of cultural eutrophication in Bear Creek Reservoir - a flood control reservoir to which the entire watershed drains. The watershed lies in the Upper South Platte River Basin -the eastern mountain headwaters to metropolitan Denver, Colorado in the United States. To initiate Phase I of the ACM DSS process, qualitative data on issues, options, social ties, and current practices were triangulated through organizational interviews, document review, a systems design group, and ongoing BCWA, community, river basin, and state-level participation. The mixed methods approach employed geographic information systems (GIS) for spatial analysis, along with statistical analysis and modeling techniques to assess reported issues and potential options quantitatively. Social network analysis (SNA) was used systematically to evaluate organizational relationships, transactions, and to direct network expansion towards a more robust core-periphery network structure. Technical and local knowledge developed through these methods were complimented by ongoing academic literature review and analysis of related watershed efforts near and far. Concurrently, BCWA member organizations helped to incrementally design and test an online toolset for greater emphasis on ACM principles in watershed program management. To date, online components of the ACM DSS include issues reporting, interactive maps, monitoring data access, group search, a topical knowledge base, projects and options tracking, and watershed and lake management plan input. Online toolset development complimented assessment by formalizing what was learned together throughout the ACM DSS process to direct subsequent actions to align with this approach. Since the online system was designed using open source software and a flexible content management system, results can be readily adapted to serve a wider variety of purposes by adjusting the underlying datasets. The research produced several potentially useful results. A post-project survey averaged 9.3 on a 10-point satisfaction scale. The BCWA board adopted the resulting ACM DSS process as a permanent best management practice, funding a facilitator to continue its expansion. A network weaver to continually foster cooperation, a knowledge curator to expand shared knowledge resources, and a systems engineer to reduce uncertainty and ambiguity and dissect complexity were all found to be critical new roles for successful ACM implementation. Watershed program comparisons also revealed ten qualities that may promote ACM. The technical analysis of nutrient issues revealed that phosphorus enrichment from phosphorus desorption from fine sediments contributed to cultural eutrophication through several distinct mechanisms, which may be addressed through a wider range of non-point source controls and in-lake management options. Potential affects from floods, wildfires, and droughts were assessed, which has resulted in more coordinated, proactive plans and studies. Next steps include formulating multi-institutional, multi-level academic studies in the watershed, expanding community engagement efforts, and establishing innovation clusters. Multi-disciplinary research needs include studying nutrient exchange processes, piloting decentralized wastewater treatment systems, optimizing phosphorus removal processes, chemically blueprinting nutrient source streams, and developing an integrated modeling framework. At least four additional stages of development are planned to refine and mature the ACM DSS process over time. The ACM DSS process is also being considered for other places and IWRM problem sets.
Open Access
A modeling tool for household biogas burner flame port design
(Colorado State University. Libraries, 2017) Decker, Thomas J., author; Bradley, Thomas, advisor; Prapas, Jason, committee member; Sharvelle, Sybil, committee member
Anaerobic digestion is a well-known and potentially beneficial process for rural communities in emerging markets, providing the opportunity to generate usable gaseous fuel from agricultural waste. With recent developments in low-cost digestion technology, communities across the world are gaining affordable access to the benefits of anaerobic digestion derived biogas. For example, biogas can displace conventional cooking fuels such as biomass (wood, charcoal, dung) and Liquefied Petroleum Gas (LPG), effectively reducing harmful emissions and fuel cost respectively. To support the ongoing scaling effort of biogas in rural communities, this study has developed and tested a design tool aimed at optimizing flame port geometry for household biogas-fired burners. The tool consists of a multi-component simulation that incorporates three-dimensional CAD designs with simulated chemical kinetics and computational fluid dynamics. An array of circular and rectangular port designs was developed for a widely available biogas stove (called the Lotus) as part of this study. These port designs were created through guidance from previous studies found in the literature. The three highest performing designs identified by the tool were manufactured and tested experimentally to validate tool output and to compare against the original port geometry. The experimental results aligned with the tool's prediction for the three chosen designs. Each design demonstrated improved thermal efficiency relative to the original, with one configuration of circular ports exhibiting superior performance. The results of the study indicated that designing for a targeted range of port hydraulic diameter, velocity and mixture density in the tool is a relevant way to improve the thermal efficiency of a biogas burner. Conversely, the emissions predictions made by the tool were found to be unreliable and incongruent with laboratory experiments.
Open Access
Anaerobic digestion of organic wastes: the impact of operating conditions on hydrolysis efficiency and microbial community composition
(Colorado State University. Libraries, 2012) Griffin, Laura Paige, author; De Long, Susan K., advisor; Sharvelle, Sybil, committee member; Stromberger, Mary, committee member
Anaerobic digestion (AD) is an environmentally sustainable technology to manage organic waste (e.g., food, yard, agricultural, industrial wastes). Economic profitability, however, remains a key barrier to widespread implementation of AD for the conversion of specific feedstocks (e.g., manure, the organic fraction of municipal solid waste (OFMSW), and agricultural residue) to energy. Specifically, high capital and operating costs and reactor instability have continually deterred the use of AD. In order to develop AD systems that are highly efficient and more cost-effective, it is necessary to optimize the microbial activity that mediates the digestion process. Multi-stage AD systems are promising technologies because they allow for separate process optimization of each stage and can enable processing of high-solids content waste. Leachate is recycled through the system, which reduces heating and pumping costs, as well as conserving water. The leachate recycle, however, leads to an increase in ammonia and salinity concentrations. At this time, the impact of reactor conditions (ammonia and salinity concentrations) on hydrolysis is not well understood. As hydrolysis is one rate-limiting step of the process in the conversion of refractory wastes (e.g., lignocellulosic materials), optimization of hydrolysis has the potential to radically improve the economic profitability of AD. The specific objectives of this research were to: 1) determine the effects of operating conditions on hydrolysis efficiency for a variety of solid wastes (manure, food waste, and agricultural residue); 2) determine hydrolysis kinetic parameters as a function of the operating conditions; and 3) identify characteristics of microbial communities that perform well under elevated ammonia and salinity concentrations. To this end, small-scale batch reactors were used to determine hydrolysis efficiency and kinetic rates. Initially, the AD sludge inoculum was exposed directly to the high ammonia and salinity concentrations (1, 2.5, 5 g Total Ammonia Nitrogen (TAN)/L and 3.9, 7.9, 11.8 g sodium/L) as would occur in a reactor treating organic waste with leachate recycle. Results demonstrated a need to acclimate, or adapt, the microorganisms to high concentrations, as methane generation was significantly inhibited with high concentrations. Thus, the organisms were acclimated for two to four months to these testing conditions. The batch studies were repeated, and results demonstrated substantial improvement in hydrolysis efficiency and methane generation. However, although differences in kinetic rates were not statistically significant, general trends in hydrolysis rates suggested that hydrolysis efficiency decreases with increased ammonia and salinity concentrations for a variety of feedstocks (i.e., manure, food waste, agricultural residue). Additionally, results demonstrated that acclimation was necessary to achieve optimal hydrolysis rates. Furthermore, microbial community composition changes in the inocula post-acclimation indicated that reactor inoculation could help improve tolerance to elevated levels of ammonia and salinity to minimize reactor start-up times and improve economic viability.
Open Access
Analysis of contaminant mass in place in transmissive and low-k zones
(Colorado State University. Libraries, 2020) Roads, Eric, author; Sale, Tom, advisor; Sharvelle, Sybil, committee member; Sutton, Sally, committee member
Contaminant hydrology has been challenged by the common perception of homogeneous subsurface media. Previous sampling methods neglect the importance of differentiating between transmissive and low-k zones. Cryogenic core collection is a high-resolution sampling technique that can highlight the occurrence of transmissive and low-k zones as well as the distribution of contaminants in transmissive and low-k zones. Cryogenic core collection uses a CSU patented process that preserves core samples downhole using liquid nitrogen. Frozen cores are shipped to CSU on dry ice and always kept at -80ᵒC. Cores are cut into subsamples and analyzed to determine geology, physical properties, contaminant concentrations, and microbial ecology. The data is processed into Excel™ and then stored in gINT™, a relational database. Herein, consideration is given to 390 feet of collected core from 31 boreholes from 5 hydrocarbon and 2 chlorinated solvent sites. Data analyses include comparisons within a site, intra-site comparisons, and between sites, inter-site comparisons. Tools are developed in gINT™ to automate transformation of collected data into vibrant visual graphical outputs. First, for every borehole, a graphic is generated that includes a comprehensive panel of geology, contaminants of concern and fluid saturations properly presented by depth. Building on this, distributions of contaminants as a function of transmissive or low-k zones are resolved. Lastly, key attributes of mass distribution are compared across individual sites (intra-site comparisons) and between sites (inter-site comparisons). Our analysis presents a first-ever quantification of distribution of contaminant mass in transmissive and low-k zones. The analysis begins with processing concentration data-by-depth to produce the total mass of contaminants in each borehole, the mass of contaminants in transmissive zones, and the mass of contaminants in low-k zones. The contaminant mass in a borehole is presented for each contaminant individually and as sum of all contaminants. The visualization of this data is not intuitive due to the ranges of contaminant mass in place. Hydrocarbons contaminated sites have contaminant masses that range from less than half a kilogram to about 30 kilograms of contaminants per m2. Chlorinated solvent contaminated sites have contaminant masses that vary from less than 240 micrograms to right under 2.5 kilograms of contaminants per m2. The data is processed such that boreholes and sites with broad ranges of conditions can be compared. Data is presented as percent of contaminant mass in transmissive zones by borehole; the percent of contaminant mass in low-k zones by borehole, the percent of borehole that is transmissive, and percent of borehole that is low-k. Unlike previous data that required a y-axis formatted to a log scale, this data is visualized on a plot with the y-axis set at 0-100%. The fraction of a borehole that is low-k ranges between 0% and 94% with a median value of 52%. Secondly, the fraction of total contaminant mass stored in low-k zone ranges from 1% to 96% with a median value of 46%. Illustrations of the tendency for mass storage in low-k zones are presented through difference in percent of borehole that is low-k and percent of contaminants in a borehole in low-k zones. The calculations defined a positive difference as preference for transmissive zones and a negative difference as preference for low-k zones. Data presented characterized the 18 hydrocarbon contaminated boreholes, 12 chlorinated solvent contaminated boreholes, and all 30 contaminated boreholes respectively. Key insights include • Hydrocarbon contaminated boreholes showed statistically significant preference for low-k zones if the unit difference of percent of borehole that is low-k and percent of contaminants in a borehole in low-k zones was less than -24%. • Chlorinated solvent contaminated boreholes showed statistically significant preference for low-k zones if the unit difference of percent of borehole that is low-k and percent of contaminants in a borehole in low-k zones was less than -11%. • Remediated chlorinated solvent boreholes presented a preference for low-k zones where their non-remediated counterparts showed preference for transmissive zones. • All contaminated boreholes showed statistically significant preference for low-k zones if the unit difference of percent of borehole that is low-k and percent of contaminants in a borehole in low-k zones was less than -19%. • As an example, this thesis provides a unique documentation of benzene persisting in low-k zones. The presence or absence of benzene in low-k zones will have a large implication with respect to the longevity of benzene in monitoring wells and the efficacy of remedial measures that address the longevity of benzene in monitoring wells. Overall, cryogenic core collection and advanced analytics provides a practical means of quantifying contaminant occurrence in transmissive and low-k zones and an improved basis for anticipating the benefits of site remedies.
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
Analysis of trace amounts to detect exposure to triclosan and triclocarban in crops grown in soil amended with human biosolids
(Colorado State University. Libraries, 2018) Malberg, Mary Gretchen, author; Ramsdell, Howard, advisor; Legare, Marie, committee member; Sharvelle, Sybil, committee member
A method to detect trace amounts of both triclosan, (TCS) and triclocarban (TCC) using gas chromatography with an electron capture detector (GC/ECD) was created to test compound uptake by dryland corn from biosolids fertilization. Corn was harvested from a field that had been amended with human biosolids since 1982 which was part of a research study being conducted by Colorado State University, College of Agricultural Sciences, Soil and Crop Sciences Department. Both TCS and TCC are lipid soluble and contain functional groups that could be derivatized. Derivatization of the compounds improved chromatography results by making compounds more volatile and stable at higher temperatures and increase detection limits to 0.05 ng/ml for TCS and 0.1 ng/ml for TCC. Derivatization was done with BSTFA (N,O-bis(trimethylsilyl) trifluoroacetamide) + 1% TMCS (trimethylchlorosilane ). The method described in this paper holds the potential for detecting other pharmaceutical products, compounds from personal care products, and over-the-counter agents that contain halogenated phenol groups. Triclocarban was not detected in corn from the control or biosolid amended fields at statistically significant amounts. Triclosan was found in increased amounts in corn that was grown in fields that were amended with biosolids. The mean results for TCS in corn from the control field were 11 μg/ml and for the bio-solid amended field the mean was 140 μg/ml, indicating that corn from bio-solid amended fields had a greater than 10-fold increase in concentrations of TCS compared to fields not amended with human biosolids.
Open Access
Applying the theories of sustainable water aid
(Colorado State University. Libraries, 2010) Douglas, Caleb Brazeal, author; Carlson, Ken, advisor; Vlachos, Evan, advisor; Mumme, Stephen P., committee member; Sharvelle, Sybil, committee member
A lack of accessibility to safe water has always been one of the greatest challenges to the rural developing world. This issue has resulted in the deaths of countless millions of people, as well as the underdevelopment of many nations. The developed world has always recognized the necessity of providing water aid to these developing nations. However, this water aid has had limited success in providing sustainable water solutions and in alleviating this crisis. Recognizing this lack of effectiveness, the theories of water aid and community development have been studied and scrutinized. This has resulted in great strides in the science of providing sustainable aid to developing nations. Yet, while much has been learned about the proper theories, little increase in success has been seen in the developing world. This study seeks to determine if one of the reasons for this lack of translated success is due to a lack of summarized and unified development principles. Therefore, this thesis attempts to collect a representative sample of literature on water aid and community development and develop a singular theory for implementing water aid. This developed procedure will serve as a step-by-step guideline that covers water aid from the community selection process to the necessity of following up with the community. This thesis will then apply this developed procedure in four communities and monitor the successes and failures. Based on this analysis, observations can be made on the viability of the new standard operating procedure. If successful, perhaps this plan could be utilized by aid organizations to provide replicable results. Additionally, observations can be made on whether a lack of collated development theories is one of the reasons for a lack of success amongst water aid. All this is done with the intention of furthering the progress of water aid, with the hope of provided greater lasting success in the developing world.
Open Access
Assessing nutrient management scenarios at the system level
(Colorado State University. Libraries, 2017) Jobin, Olivia, author; Arabi, Mazdak, advisor; Hoag, Dana, committee member; Sharvelle, Sybil, committee member
The exponential increase in urbanization and population has led to water quality degradation throughout the country. This can be linked to the increase in impervious surfaces from urban expansion, most wastewater treatment plants (WWTPs) not being equipped to handle higher nutrient inflows, and the exponential demand for food that has led to more intensive farming practices that erode and degrade the soil, further enhancing runoff. The overall goal of this study was to assess nutrient management scenarios at the system level. The objectives included: 1) determine a methodology that could be used to quantify nutrient load contributions from each sector at the watershed scale; 2): determining delivery ratios for each sector based on the ambient nutrient loads at the outlet of the watershed; 3): and assess the cost, equity, and water quality effects of conservation management practices, BMPs, wastewater treatment technologies, and water conservation practices. Assessing the effectiveness of agricultural management practices is often jeopardized by lack of comprehensive monitoring data and computational burden at larger scales. The Soil and Water Assessment Tool (SWAT) within the eRAMS platform was used to assess the benefits of different agricultural management practices at field and watershed scale for the South Platte River Basin (SPRB), a moderately large semi-arid watershed located in northeastern Colorado. The model was calibrated using measured field observations from a study site in the watershed where the target management practices were implemented and monitored for their effectiveness. The agricultural management practices studied included fertilizer application rate and timing, tillage practices (i.e. conventional, reduced, strip, and no-tillage), and center pivot versus surface irrigation for roughly 21,000 irrigated agricultural fields (740,000 acres) in the SPRB. Center pivot irrigation showed the highest potential for nutrient reduction while tillage practices had an intermediate effect. Due to interim warm water instream total nitrogen (TN) and total phosphorus (TP) levels being exceeded over the period of 2002-2015, nutrient management scenarios were assessed at the system level for the Cache la Poudre (CLP) watershed in Colorado. The CLP watershed consists of 13 WWTPs, as well as irrigated agricultural fields, forested land, rangeland and urban areas making it an ideal candidate for this analysis. The scenarios created involved a combination of different practices and technologies for each sector and their associated costs to determine cost effective solutions for the issue at hand. A Gini Index coefficient was also determined in order to determine how equitable each scenario was. Models were used to determine the nutrient load contributions over the 14 year time frame with and without the implementation of the different practices and technologies tested, and were validated based on previous research and monitoring data. It was found that TN reductions needed for regulations could be achieved through the adoption of carbon addition, WWTP effluent reuse, 10% adoption of strip tillage, and a 25% adoption of bio-retention basins for a total of roughly $6,000,000. Whereas the TP reduction needed for regulations for all hydrologic conditions could not be achieved with any combination of the practices looked into, however 2 out of the 3 reductions could be achieved from the adoption of Chem-P, WWTP effluent reuse, 10% adoption of strip tillage, and 25% adoption of bio-retention basins for roughly $11,000,000. Further research would be needed to determine a scenario that could achieve a 70% TP reduction and 40% TN reduction simultaneously at the outlet, which was needed at the system level to be in compliance with regulatory standards.
Open Access
Assessing of performance of stormwater control measures under varying maintenance regimes
(Colorado State University. Libraries, 2020) Joseph George, Alfy, author; Arabi, Mazdak, advisor; Sharvelle, Sybil, committee member; Ronayne, Michael, committee member
Stormwater control measures (SCMs) are being installed worldwide to curb urbanization impacts such as flooding, stream degradation, nutrient pollution, and contaminant loading in receiving water bodies. Regular inspection and maintenance are important to ensure long term effective performance of SCMs over their design life. This study investigates the performance, reliability, and time to failure of permeable pavement, a filtration based SCM, as a function of the design life and different maintenance strategies. The Stormwater Management Model (SWMM) is used to simulate performance of infiltration based SCMs under different climate and operational conditions including different maintenance regimes. A probabilistic approach is developed to characterize the risk, reliability and vulnerability of the system. Performance data including the effects of clogging and maintenance was obtained from comprehensive literature review of numerous international studies on performance of SCMs under different maintenance activities and strategies. The method of Sobol' global sensitivity analysis is used to evaluate the predictive uncertainty in the estimated surface overflow/bypass flow, runoff, and infiltration to characterize uncertainty in the input parameters of SWMM. Risk-based evaluation metrics are defined and characterized to assess the performance and probability of failure of the systems. A hazard function approach is used to characterize the time to failure of the systems under full, partial, and no maintenance regimes. Results indicate that maintenance plays a significant role in the simulated flow budgets and the performance of infiltration based SCMs. The time to failure of the systems is substantially increased by partial maintenance, while full maintenance marginally increases the time to failure compared to the partial maintenance regime. The analysis can be used to develop effective maintenance strategies for SCMs to ensure longevity and reliability of SCMs over their design life.
Open Access
Assessing the on-farm effects of removing salts from irrigation water
(Colorado State University. Libraries, 2023) Shrestha, Sanskriti, author; Bailey, Ryan, advisor; Sharvelle, Sybil, committee member; Butters, Gregory, committee member
In dry and semi-arid places where precipitation is insufficient to sustain a regular percolation of water through the soil, salt-induced land degradation is frequent. Desalination of irrigation water is an emerging alternative that can be utilized to repurpose our salt-affected agricultural lands, thus providing an avenue for sustaining the growing production demands with limited water and land resources. Therefore, a combination of fieldwork, modeling and soil sensor records was implemented to evaluate the feasibility of an on-farm Reverse Osmosis (RO) system, in terms of crop yield and soil salinity, for the desalination of irrigation water over three growing periods. Four types of treatment systems were applied to 16 experimental field plots at the Arkansas Valley Research Center (Rocky Ford, CO), representing soil conditions of the Lower Arkansas River Valley (LARV), a region of which approximately 70% is affected by salt-induced crop yield loss. Statistical t-tests done on the data of the three seasons did not show any significant differences in the VMC, EC and biomass of the plots irrigated with the different treatments. Results of the tests for season 3, which showed an increase in t-values and a decrease in p-values demonstrated the need for a longer study period to gauge any significant effects. Similarly, the results of sensor data did not show a significant decrease in soil salinity for the study period. The average soil electrical conductivity (EC) showed a 20% to 26% reduction in soil salt mass in the fields irrigated with desalinated water over the three seasons, however, the EC results did not show a consistent decreasing trend across the 16 plots. A 6-year numerical modeling forecast done by the hydro-chemical model HYDRUS 1D simulating dry, average, and wet weather showed a 6% to 20% reduction in EC when desalination was applied to the fields. These preliminary results of the field and modeling approaches provide encouragement for the continuation of desalination treatments to see any substantial long-term effects.
Open Access
Assessing the salinity effects and economic feasibility of on-farm desalination technology in irrigated semi-arid regions
(Colorado State University. Libraries, 2021) Barnes, Kaitlyn, author; Bailey, Ryan, advisor; Sharvelle, Sybil, committee member; Melzer, Suellen, committee member
High salinity levels in areas with intensive agricultural practices can inhibit agricultural productivity. Semi-arid regions where irrigation is used to support crop growth are particularly impacted by the quality of surface and groundwater sources. In this study, we use a combined numerical modeling and economic analysis approach to estimate the regional impact of an on-farm desalination technology on multi-decadal salinity fate and transport and explore whether the technology is viable to improve soil health, crop yield, and long-term profitability. A subsurface salt transport model (MODFLOW-RT3D) is applied to a 50,600-ha (125,000 acres) region in southeastern Colorado located within the Arkansas River Valley. The model simulates the reactive transport in soils and groundwater of 8 major salt ions (Ca+, Mg2+, Na+, K, SO42-, CO32-, HCO3-, and Cl-). Simulated values of average soil water concentration (TDS) are used to estimate crop relative yield with and without salt removal at various removal rates (Baseline – no salt removed; Unit removal – average of 60% salt removed; 100% salt removal) and time periods (5, 10, 15, 20, 25 years after desalination begins). The Unit removal rate is calibrated to align with a solar powered, reverse-osmosis desalination system that is currently being tested in semi-arid study area. For the Unit rate of 60% salt removal, the average TDS of the study area was found to decrease by an average of 20% over a period of 20 years, resulting in an increase in crop yield of 1.6 – 2.3%. Using data on regional production costs, crop prices, and the costs of building and operating the desalination system, we calculate the Net Present Value of production with the desalination unit. The results indicate that desalination does increase economic returns, particularly for high-valued specialty crops, such as melons and onions; however, these benefits are considerably less than the costs of operating the desalination technology.
Embargo
Assessing the triple bottom line co-benefits and life cycle cost tradeoffs of cloudburst infrastructure in New York City
(Colorado State University. Libraries, 2024) Fenn, Abby M., author; Arabi, Mazdak, advisor; Grigg, Neil, committee member; Sharvelle, Sybil, committee member; Conrad, Steve, committee member
Urbanization and climate change have increased the risk of urban flooding. Specifically, more frequent cloudburst events are on the rise in cities across the globe. Cloudbursts are characterized by high intensity rainfall over a short duration, causing unpredictable, localized flooding. Effective stormwater management is essential to manage extreme precipitation and runoff induced by cloudbursts. Stormwater control measures have evolved over time shifting from gray infrastructure to nature-based and green solutions. Recently, cloudburst specific infrastructure has emerged as a stormwater intervention strategy designed to handle larger volumes of water by capturing, storing, or conveying excess water in highly impervious areas. Cloudburst infrastructure systems are inextricably linked with land use in cities and thus, their implementation should incorporate life cycle costs, and social and ecological co-benefits. This study assesses the Triple Bottom Line co-benefits and environmental effects of cloudburst systems for flood control in New York City. Specifically, we explore the tradeoffs between the costs and co-benefits of alternative surface vegetation including grass, diverse vegetation, and trees. The study identifies the Pareto optimal set of solutions and quantifies effects of incorporating vegetation into the urban landscape via cloudburst systems. The results indicate that surface vegetation plays a key role in altering the co-benefits and life cycle costs of cloudburst infrastructure. Trees were the most frequent non-dominated solution and were linearly related to Triple Bottom Line score and exponentially related to Life Cycle Cost. The framework and results of this study provide valuable insight to support informed decision-making.
Open Access
"Biofilmomics": functional protein expression in biofilm biotechnologies revealed by quantitative proteomics
(Colorado State University. Libraries, 2020) Chignell, Jeremy, author; Reardon, Kenneth, advisor; De Long, Susan, advisor; Peebles, Christie, committee member; Sharvelle, Sybil, committee member
Microbial biotechnologies that utilize biofilms often exhibit superior performance compared with planktonic systems. Many details of biofilm metabolism that drive those improvements in performance remain unclear. Only recently have molecular tools emerged that can provide a holistic picture of life in a complex biosystem like a biofilm for the purposes of answering questions on a system level. The purpose of this work was to address four fundamental questions about protein expression in biofilms: what kind of protein expression is distinctive to biofilms? Which biofilm proteins are associated with a function of interest? How does co-culture with another species affect biofilm-related protein expression? When during multi-species biofilm development does a function of interest emerge and who in the community is responsible? Label-free quantitative proteomics was used in conjunction with physiological experimentation to address these four questions. In the first study we found that L. delbrueckii lactis protein expression in flow-cell biofilms was 31% more diverse than in planktonic cultures, and proteins related to catalytic activity were significantly increased in biofilms at the expense of proteins for cell motility and replication. Roles for riboflavin and fatty acid metabolism suggested modulations in redox functions and membrane turnover during life in a biofilm. The second study compared protein expression by S. onedensis MR-1 in electricity-generating biofilms with that in aerobic biofilms from the same microbial fuel cell reactor. Three novel proteins associated with electricity generation were identified, in addition to proteomic evidence of aerobic metabolism by anode biofilm cells. The latter result was shown to be consistent with kinetics of oxygen depletion and bulk cell growth in the MFC, suggesting operational conditions to reduce this bulk cell growth and thereby reduce fouling of the cathode and improve overall Coulombic efficiency of the single-chamber MFC system. In the third study, it was discovered through proteomic and physiological experiments that a virulent phenotype associated with biofilm formation was triggered in P. putida when co-cultured with B. atrophaeus. Dramatic shifts in protein expression at the initial trigger point of virulent biofilm formation by P. putida are described. Finally, a comparison of the meta-proteomes of microbial fuel cell biofilms at different stages of development indicated that proteins in metabolic pathways for carbon storage and competitive inhibition are differentially expressed when the biofilm becomes electrochemically active. Meta-proteomics and 16S rRNA gene sequencing agreed that it is possible for a microbial fuel cell community to maintain high diversity (and therefore potentially higher resilience) while generating electricity at levels comparable to a MFC community dominated by Geobacter. Each of these chapters was prepared as an independent manuscript, though the themes were integrated by the overall theme of quantifying differential protein expression in biofilms in order to reveal new details about their development and functionality. Since the performance of many engineered biosystems—including those that employ biofilms—often can be controlled adequately at an operational level, an attitude persists that any additional molecular investigation is superfluous. The work presented here provides evidence for the opposite viewpoint: a rich understanding of the molecular mechanisms behind biofilm functionality can inform strategies for continuous system improvement and suggest new capabilities and biotechnological applications of biofilms.
Open Access
Characterization of co-benefits of green stormwater infrastructure across ecohydrologic regions in the United States
(Colorado State University. Libraries, 2020) Rainey, William, author; Arabi, Mazdak, advisor; Sharvelle, Sybil, committee member; McHale, Melissa, committee member
Green stormwater infrastructure (GSI) systems such as rain gardens, permeable pavement and bioswales are commonly used in municipalities to reduce urban flooding and water pollution. In conjunction with these direct benefits, GSI systems provide additional social and ecological "co-benefits". Our goal was to investigate the co-benefits of commonly used GSI systems in five cities in the United States, including Baltimore, Denver, New York City, Philadelphia, and Portland. Specifically, carbon storage, carbon sequestration, air pollution removal, UV reduction, and cooling effects of the trees used in GSI in the study cities were quantified. The i-Tree Eco urban forestry model was used to predict various co-benefits for individual tree species and total SGI tree inventories across the five study cities based on observed tree characteristic data. Aspects of SGI design, environmental factors, and model inputs were evaluated to find what influences the assessment of SGI co-benefits. SGI design types and utilization levels of those designs played a big role in determining the number of trees used in SGI projects, however there is more nuance to the evaluation of co-benefits of different cities' SGI trees than just the tree population. Climate was a large influence on co-benefits' estimation, with similar co-benefit responses for cities with similar climates, like the eastern seaboard. The inputs that influence co-benefit predictions the most were evaluated using global sensitivity analysis. We also found that the inputs that represent the tree growth and environmental factors heavily influenced the computation of co-benefits in i-Tree Eco. Our research supports current literature in developing SGI programs that provide the most amount of co-benefits for specific climates. This study aims to reveal more about the mechanisms and prevailing equations within i-Tree Eco by providing modelled datasets and assessment approaches to estimate the co-benefits of GSI at unit and city levels.
Open Access
Characterization of the vulnerability of urban streams to nutrient pollution under varying flow regimes
(Colorado State University. Libraries, 2019) Heiden, Chelsey, author; Arabi, Mazdak, advisor; Sharvelle, Sybil, committee member; Covino, Tim, committee member
Nutrient pollution is a primary cause of water quality impairment in streams in the United States and throughout the world. Regulatory approaches under the Clean Water Act, such as water quality standards and the Total Maximum Daily Load program, aim to improve water quality. In this study, novel probabilistic methods are developed to characterize vulnerability to nutrient pollution along urban streams and to assess risk of water quality impairment under varying hydrologic conditions. Vulnerability is defined as the probability that ambient conditions exceed desired water quality standards. Both EPA ecoregional and state-level targets are included in the analysis. Specifically, the study i) explores relationships between urban influences and risk to nutrient pollution; and ii) expands on the load duration curve framework to quantify vulnerability to nutrient pollution as a function of flow exceedance probability. The study objectives are examined at 20 stream locations in four ecohydrologically different regions across the United States, including Denver, CO; Phoenix, AZ; Portland, OR; and Baltimore, MD. Total phosphorus (TP) and total nitrogen (TN) water quality data collected between 1990 and 2018 with daily discharge measurements are utilized in the analysis. Indicators of urban influence include wastewater treatment capacity, urban land cover, impervious surfaces, and population density. In general, study locations exhibit vulnerability (greater than 5%) to nutrient impairment across urban gradients, including some relatively undisturbed monitoring locations. Nearly 30% of TP sites and 45% of TN sites are impaired under state level regulation. Results indicate that incorporation of more stringent EPA ecoregional targets lead to higher vulnerability estimates than those corresponding to the state-level targets. Over 70% of TP sites and 55% of TN sites with state level standards are characterized as vulnerable (greater than 5%) when EPA goals are considered. Patterns of impairment through urban gradients are more evident in arid regions with wastewater-dominated river flows, specifically in Denver and Phoenix, than humid regions. Multiple linear regressions between indicators of urban influence and vulnerability provide strong (R2 > 0.7) relationships for most monitoring locations. Inverse distance weighted annual wastewater treatment facility flow capacity and urban land cover are the most significant predictors. However, the most important nonpoint source exploratory variable differ from site to site. More monitoring locations are required to determine model significance. In addition, assessment of nutrient pollution vulnerability using the enhanced load duration approach show that higher vulnerability to impairment tends to occur under consistent hydrologic conditions within each city. For example, high vulnerability to TN and TP impairments are observed under low flow conditions at sites within and around the Denver incorporated area. Conversely, nutrient levels during high flow conditions are more likely to exceed the TN and TP standards in Phoenix, Baltimore, and Portland. Many locations are vulnerable to nutrient pollution (greater than 5%) under all possible flow scenarios, especially at downstream monitoring locations. Approximately 85% of TP sites and 70% of TN sites are vulnerable under all flow conditions assuming EPA water quality goals. The methodology developed in this study can be used to probabilistically quantify the vulnerability to water quality impairments in streams and to identify hydrologic conditions under which higher vulnerabilities prevail.
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
Design and fabrication of a 3-D printable counter-flow/precipitation heat exchanger for use with a novel off-grid solid state refrigeration system
(Colorado State University. Libraries, 2016) Ryan, Sean Thomas, author; Marchese, Anthony, advisor; Kirkpatrick, Allan, committee member; Sharvelle, Sybil, committee member
Off-grid refrigeration technologies are currently limited to either vapor-compression cycles driven by photovoltaics or solar thermal absorption cycles. Rebound Technologies has recently developed a novel off-grid refrigeration system called SunchillTM for agricultural applications in humid environments in the developing world. The SunchillTM refrigeration system utilizes the daily high and low temperatures to drive a 24 hour refrigeration cycle. Cooling is provided by the dissolution of an endothermic salt, sodium carbonate decahydrate. Once the salt is solvated and cooling is delivered to freshly harvest crops, the system is “recharged” in a multi-step process that relies on a solar collector, an air-gap membrane unit and a heat exchanger. The heat exchanger, which is the focus of this thesis, is required to remove 36.6 MJ of heat over a twelve hour period in order to “recharge” the system. The heat exchanger is also required to transfer heat from a fresh water stream to a cold brine solution to generate the cold water necessary to submerse and cool harvested crops. To provide a sustainable technology to the target community, the feasibility of fabricating the heat exchanger via the low cost 3-D printing method of fused filament fabrication (FFF) was examined. This thesis presents the design, development, and manufacturing considerations that were performed in support of developing a waterproof, counter-flow, 3-D printable heat exchanger. Initial geometries and performance were modeled by constructing a linear thermal resistance network with truncating temperatures of 30°C (saturated brine temperature) and 18°C (average daily low temperature). The required surface area of the heat exchanger was found to be 20.46 m2 to remove the required 36.6 MJ of heat. Iterative print tests were conducted to arrive at the wall thickness, hexagon shape, and double wall structure of the heat exchanger. A laboratory-scale heat exchanger was fabricated using a Lulzbot Taz 4 printer from acrylonitrile butadiene styrene (ABS) polymer. Performance was verified empirically for the laboratory-scale unit. A heat transfer rate of 22.8 W was obtained at a flow rate of 0.00075 kg/s. The results of this thesis demonstrate the feasibility of manufacturing low cost heat exchangers using additive manufacturing techniques.
Open Access
Development of a solid human waste semigasifier burner for use in developing countries
(Colorado State University. Libraries, 2014) Loveldi, Nathan, author; Marchese, Anthony J., advisor; DeFoort, Morgan, advisor; Sharvelle, Sybil, committee member; Mizia, John, committee member
Recent estimates suggest that approximately 40% of the world's population does not have access to an adequate sanitation system. This lack of access is one of the major causes of child mortality, mainly due to diarrhea. In an attempt to increase access to sanitation, the Bill and Melinda Gates Foundation proposed a program called the Reinvent the Toilet Challenge. The challenge is to develop sustainable toilets that can be used in areas without an electrical grid or sanitary plumbing. These criteria allow the toilet to be placed in rural areas without access to an electrical grid and in environments where water is scarce. This thesis describes the design and development of a solid human waste semi-gasifier burner for use in developing countries that was developed in response to the Reinvent the Toilet Challenge. The incineration process was chosen because the high operating temperature ensures the elimination of pathogens. The device was developed by understanding the fundamentals of fecal material combustion. Several design iterations were constructed to systematically optimize the critical variables. Those variables include char production, air flow rate requirement, ignition sequence, and power source requirement. The result is a prototype powered by a single 12 Volt battery that can incinerate solid waste. A thermoelectric generator is used to harvest the heat from combustion and convert the heat back into electricity. The exhaust gas from the combustion is used for drying of fecal material. Both the thermoelectric generator and exhaust gas usage provide a sustainable energy source for the toilet.
Open Access
Development of advanced microbial communities for enhancing waste hydrolysis processes: insights from the application of molecular biology tools
(Colorado State University. Libraries, 2016) Wilson, Laura Paige, author; De Long, Susan K., advisor; Sharvelle, Sybil, committee member; Bareither, Christopher, committee member; Weir, Tiffany, committee member
Anaerobic digestion (AD) is an environmentally attractive technology for conversion of various solid wastes to energy. However, despite numerous benefits, AD applications to OFMSW remain limited in North America due to economic barriers with existing technologies. Suboptimal conditions in anaerobic digesters (e.g., presence of common inhibitors ammonia and salinity) limit waste hydrolysis in AD and lead to unstable performance and process failures compromising economic viability. To guide development of microbial management strategies to avoid process upsets and failures due to inhibitors, hydrolysis rates were determined in batch, single-stage digesters seeded with unacclimated or acclimated inocula under a range of ammonia and salinity concentrations for two model feedstocks (food waste and manure). Using unacclimated inocula, hydrolysis was found to be severely inhibited for elevated ammonia (decrease of nearly 4-fold relative to baseline) and salinity (decrease of up to 10-fold relative to baseline). However, for inocula acclimated over 2 to 4 months, statistically significant inhibition was not detectable except in the case of food waste subjected to elevated ammonia concentrations (p-value = 0.01). Inhibitors and feedstock were found to have a major influence on bacterial community structure. Next, a more detailed analysis of the acclimation process revealed that microbial communities under stressed conditions (elevated ammonia) adapt more slowly (weeks) to feedstock changes (from wastewater sludge to manure or filter paper) than under non-stressed conditions (days). Molecular tools were utilized to separate temporal effects on hydrolyzers from temporal effects on methanogens. Bacterial and archaeal sequencing results identified multiple organisms (e.g., Clostridiales vadinBB60, Ruminococcaceae, Marinilabiaceae, Methanobacterium, and Thermoplasmatales Incertae Sedis) that were selected for in microbial communities in stressed reactors under perturbed conditions (feedstock changes). Collectively, results from these studies suggested that weeks of acclimation are required to build up sufficient quantities of desired hydrolyzing microbes; thus, hydrolysis processes operated in batch mode should be inoculated with each new batch, and desired microorganisms should be maintained in the system via properly developed inoculation strategies. To identify improved methods of maintaining such communities in multi-stage reactor systems, reactor performance under elevated ammonia and salinity was compared for leach bed reactors (LBRs) seeded with unacclimated inoculum and different ratios of acclimated inoculum (0-60% by mass) at start-up. Additionally, the effect of seeding methods was examined by identifying the optimal ratio of fresh waste to previously digested waste in multi-stage systems incorporating leachate recycle during long-term operation. Results demonstrated that high quantities of inoculum (~60%) increase waste hydrolysis and are beneficial at start-up or when inhibitors are increasing. After start-up (~112 days) with high inoculum quantities, leachate recirculation leads to accumulation of inhibitor-tolerant hydrolyzing bacteria in leachate. During long-term operation, low inoculum quantities (~10%) effectively increase waste hydrolysis relative to without solids-derived inoculum. Additionally, molecular analyses indicated that combining digested solids with leachate-based inoculum doubles quantities of Bacteria contacting waste over a batch and supplies additional desirable phylotypes Bacteriodes and Clostridia. To provide detailed insight into microbial community activity during degradation, metatranscriptomic analyses were conducted on reactors fed food waste and manure under low ammonia, and several common active (e.g., Methanomicrobia, Methanosaeta concilii, and Clostridia) and unique active (e.g., Enterobacteriaceae, Clostridium thermocellum, and Clostridium celluloyticum) phylotypes between the reactors were identified. Functional classification of the active microbial communities generally revealed several similarities between the reactors despite the differences in feedstock. However, similarities or differences in transcript abundance for specific gene categories (e.g. one-carbon metabolism or fermentation) might indicate some potentially useful biomarkers for monitoring process health. Additionally, data from this experiment expanded the gene sequence database for assay development, which is particularly key for improving current functional gene-targeted assays to more accurately characterize microbial communities. Overall, results from this study have provided operational guidance for establishing and maintaining desired microbial communities as inocula to enhance waste hydrolysis for a variety of feedstocks.