Mountain Scholar :: Browsing by Author "Sharvelle, Sybil, advisor"

Browsing by Author "Sharvelle, Sybil, advisor"

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Open Access
A collaborative planning framework for integrated urban water management with an application in dual water supply: a case study in Fort Collins, Colorado
(Colorado State University. Libraries, 2018) Cole, Jeanne Reilly, author; Sharvelle, Sybil, advisor; Grigg, Neil, advisor; Arabi, Mazdak, committee member; Goemans, Chris, committee member
Urban water management is essential to our quality of life. As much of our urban water supply infrastructure reaches the end of its useful life, water managers are using the opportunity to explore alternative strategies that may enable them to better meet modern urban water challenges. Water managers must navigate the labyrinth of balancing stakeholder needs, considering all costs and benefits, reducing decision risk, and, most importantly, ensuring public health and protecting the environment. Innovative water managers need guidance and tools to help manage this complex decision space. This dissertation proposes a collaborative, risk-informed, triple bottom line, multi-criteria decision analysis (CRTM) planning framework for integrated urban water management decisions. The CRTM framework emerged from the obstacles and stakeholder needs encountered during a study evaluating alternative dual water supply strategies in Fort Collins, Colorado. The study evaluated four strategies for the dual supply of raw and treated water including centralized and decentralized water treatment, varying distribution system scales, and integration of existing irrigation ditches with raw water landscape irrigation systems. The results suggest that while the alternative dual water supply strategies offer many social and environmental benefits, the optimal strategies are dependent on local conditions and stakeholder priorities. The sensitivity analysis revealed the key parameters driving uncertainty in alternative performance were regulatory and political reinforcing the importance of participation from a wide variety of stakeholders. Evaluation of the decision process suggests the CRTM framework increased knowledge sharing between study participants. Stakeholder contributions enabled a comprehensive evaluation of the option space while examining the financial, social and environmental benefits and trade-offs of the alternatives. Most importantly, evolving the framework successfully maintained stakeholder participation throughout the study.
Open Access
A cross sector evaluation comparing nutrient removal strategies in urban water systems
(Colorado State University. Libraries, 2019) Hodgson, Brock, author; Sharvelle, Sybil, advisor; Arabi, Mazdak, committee member; Carlson, Ken, committee member; Hoag, Dana, committee member
Water supply management and reduction of nutrient pollution from urban water systems are two of the most important issues facing utility managers today. To better protect water supplies, many states have or are establishing total nitrogen (TN) and/or total phosphorous (TP) loading restrictions from urban water systems. Traditionally, these targets are met by wastewater treatment facility (WWTF) improvements, but stringent regulations can make this challenging and costly. As regulations increase it may be necessary or more cost effective to consider additional options for nutrient removal from urban water systems including water management practices or stormwater control measures (SCMs). There are a wide range treatment approaches that can be considered at a WWTF for improving nutrient removal but evaluating these scenarios can be challenging and is traditionally accomplished via mechanistic models specific to individual WWTFs requiring process expertise and a rigorous sampling and analysis program. Water management practices are traditionally considered for water supply improvement, however there is little research to characterize the impact on water quality. There is a need for additional research and tools that facilitate estimating effectiveness of various nutrient removal technologies and consider cross sector strategies and tradeoffs between adoption of practices. To understand the impacts of water management practices, the impact of indoor conservation, source separation, and graywater and effluent reuse on WWTF influent and effluent and downstream water quality was characterized identifying which practices can potentially help meet nutrient reduction targets. For WWTF technologies, previously calibrated and validated mechanistic models were used to develop a simplified empirical model to more easily estimate and compare the effectiveness of various WWTF technologies as a function of influent wastewater quality. The findings from the water management practice evaluation and WWTF treatment comparison provided the framework for conducting an urban water systems evaluation by using the developed empirical models combined with the benefit of stormwater control measures (SCMs) characterized via the Simple Method to evaluate a multitude of strategies for meeting nutrient removal targets in the urban water system. Lastly, this research considered the impacts on biosolids management with the increase of liquid stream removal at the WWTF. The research identified source separation and effluent reuse as frequent part of effective nutrient removal strategies and part of an optimal nutrient removal strategy, and even necessary under stringent nutrient requirements. In terms of wastewater treatment, the benefit of adopting more advanced wastewater treatment processes will be most beneficial in carbon limited WWTFs, and negligible when there is adequate carbon for biological nitrogen and phosphorous removal. This includes sophisticated processes like nitrite shunt and 5-Stage Bardenpho and sidestream processes like struvite precipitation and ammonia stripping. While improvements to WWTF are likely with adoption of stringent nutrient regulations a multi objective optimization identified water management practices and SCMs to be part of all non-dominated nutrient removal strategies. As nutrient requirements become more stringent, the options for WWTFs in terms of processes are limited and frequently a combination of water management practices and SCMs is necessary. This was demonstrated via a systems analysis of cost-effective nutrient removal solutions in urban water systems that can be easily applied to other urban systems because of the empirical models developed with this research. These tools are necessary to help utility managers identify optimal nutrient removal strategies. As utilities invest in improvements to WWTF operations, there may also be notable impacts on biosolids management, primarily in terms of phosphorous, which may limit land application rates resulting in additional cost or disposal of biosolids that historically have been beneficially used in agriculture. These impacts must also be considered by utility managers when considering optimal nutrient removal strategies from urban water systems.
Embargo
Addressing barriers to the wide-scale implementation of roof runoff and stormwater collection and use projects for non-potable end uses in the U.S.
(Colorado State University. Libraries, 2023) Alja'fari, Jumana Hamdi Mahmoud, author; Sharvelle, Sybil, advisor; Arabi, Mazdak, committee member; De Long, Susan, committee member; Nelson, Tracy, committee member
Roof runoff and stormwater have the potential to serve as important local water sources and diversify the water budget portfolio in regions with dwindling water supplies and increasing populations. Due to the lack of guidance regulating the use of roof runoff for non-potable end uses, characterizing its microbial quality is necessary to promote roof runoff use across the U.S. Similarly, the degree of stormwater microbial contamination is still not well understood, and uncertainty about the required treatment is a barrier for the implementation of stormwater capture and use (SCU) projects. Stormwater runoff could become contaminated with human fecal matter in areas with aging infrastructure where raw wastewater exfiltrate from sewer networks to stormwater collection networks, areas with homeless encampments, or areas with sanitary sewer overflows (SSOs). Stormwater practitioners wanting to benefit from stormwater to augment the available water resources struggle with the selection and design of efficient stormwater treatment trains that are protective of public health for the designated end use. Knowledge of the degree to which stormwater is contaminated with human fecal matter, termed here as the human fecal contamination analog (HFCA), is critical for the design process and estimating the required pathogen log reduction targets (LRTs).To address the barrier to wide-scale implementations of roof runoff collection and use projects, a 2-year research study was designed to examine roof runoff microbial quality in four U.S. cities: Fort Collins, CO; Tucson, AZ; Baltimore, MD; and Miami, FL. Sample collection was conducted as part of a citizen science approach. The occurrence and concentrations of indicator organisms (E. coli and enterococci) and potentially human-infectious pathogens (PHIPs) including Salmonella spp., Campylobacter spp., Giardia duodenalis, and Cryptosporidium parvum in roof runoff were determined using culture methods and digital droplet polymerase chain reaction (ddPCR), respectively. E. coli and enterococci were detected in 73.4% and 96.2% of the analyzed samples, respectively. Concentrations of both E. coli and enterococci ranged from <0 log10 to >3.38 log10 MPN/100 mL. Salmonella spp. invA, Campylobacter spp. ceuE, and G. duodenalis β – giardin gene targets were detected in 8.9%, 2.5%, and 5.1% of the analyzed samples, respectively. Campylobacter spp. mapA and C. parvum 18S rRNA gene targets were not detected in any of the analyzed samples. This dataset represents the largest-scale study to date of enteric pathogens in U.S. roof runoff collections and will inform treatment targets for different non-potable end uses for roof runoff. To address barriers to the wide-scale implementation of SCU projects for non-potable end uses, stormwater microbial contamination originating from human fecal matter was examined using the detection frequencies and concentrations of human microbial source tracking (MST) markers and PHIPs observed in stormwater. Measurements of human MST markers in wet weather flows, dry weather flows, and influent wastewater in addition to measurements of viral and protozoan pathogens in wet weather flows and influent wastewater were compiled through a systematic review. Human MST marker and PHIP datasets were statistically analyzed and used to estimate HFCAs based on relative concentrations of microbial contaminants in stormwater compared to municipal wastewater. Analytical statistical distributions of the original data, unpaired Monte Carlo simulation, and paired Monte Carlo simulation were applied for the estimates of HFCAs in wet and dry weather flows. Estimates of human MST-based HFCAs are more reliable than PHIP-based HFCAs because the current PHIP datasets are limited by detection limits and the range of data observed within the statistical distributions. Unpaired Monte Carlo simulations and analytical statistical distributions were found to be the best methods for the estimation of human MST-based HFCAs in wet and dry weather flows which ranged from <10-7.0 to 10-1.5 and 10-12 to 10-2.6, respectively. Pathogen LRTs were determined in this study using HFCAHuman MST Markers and previously published quantitative microbial risk assessments (QMRAs) to guide the selection of stormwater treatment process trains based on the intended end use (e.g., unrestricted irrigation or indoor use) of stormwater. Combinations of stormwater treatment trains at varying HFCA levels were evaluated based on complexity and reliability of the suggested trains. To use stormwater safely for unrestricted irrigation and indoor uses, treatment trains containing both filtration and disinfection unit processes are required. The HFCA threshold beyond which the complexity of stormwater trains becomes considerably higher is 10-4. Performance evaluation of the suggested stormwater treatment trains revealed that trains consisting of membrane filtration and at least two disinfection unit treatment processes, specifically ultraviolet (UV) and ozone (O3) or UV and chloramine are recommended at HFCA values of 10-3, 10-2, and 10-1. At HFCA value of 10-4, a treatment train consisting of membrane filtration and O3 or chloramine is recommended. The use of free chlorination at all HFCA levels is not recommended due to the high continuous monitoring requirements associated with the use of free Cl2.
Open Access
Aerobic post-processing of digestate from a multi-stage anaerobic digester
(Colorado State University. Libraries, 2017) Sandefur, Julie N., author; Sharvelle, Sybil, advisor; DeLong, Susan, committee member; Davis, Jessica, committee member
The management of animal waste from feedlots is inconvenient and costly due to the storage and transportation involved in ensuring the waste is utilized appropriately. Anaerobic digestion is a proven method for breaking down waste with low solids content and capturing methane produced to use as renewable energy. Composting is an age-old process in which solid waste retains its nutrients and becomes a suitable, natural soil amendment. By combining these methods within multi-stage anaerobic digestion (MSAD), two valuable by-products are generated – methane and nutrient-laden compost – through a process able to handle high solids material. A laboratory-scale study was conducted to simulate aerobic composting of high solids cow manure (HSCM) in a leachate bed reactor (LBR) after anaerobic digestion from a MSAD. Analysis of the leachate and solid material were performed after each phase: anaerobic – 21 days, active aerobic – 21 days, and curing - 60 days. The effects of agricultural by-products used as bulking material in the LBRs and of compost inoculum added were also assessed. The bulking material assisted in providing uniform flow of leachate through the LBRs during the anaerobic phase and served as an additional carbon source once aeration began. Inoculum acquired from Colorado State University's (CSU) composter was added at the beginning of the aeration phase via two different methods alongside a control group in order to assess the potential contributions of including already composted organic material still containing active bacteria. Compost quality parameters monitored consisted of ammonium to nitrate ratio, carbon to nitrogen ratio, pH, soluble salts, sodium absorption ratio (SAR), percent total nitrogen, phosphorus, and potassium, and the Solvita® Maturity Index (SMI). There was a sizable volatile solids reduction (%VS) observed of the HSCM only in two of the three different bulking material reactor sequences. The bulking material study showed a 41% ± 0.12, 33% ± 0.03 and 55% average reduction in the manure for corn stover, beanstalk, and woodchip reactors respectively. The woodchips most likely contributed to the larger solids reduction due to their larger particle size and more rigid structure allowing leachate and air more pathways to access and breakdown material. VS reduction in the inoculum study showed that there was no solids reduction benefit achieved by including a 1:2 municipal solid waste (MSW)-horse manure combined inoculated compost to the reactors prior to the active aeration phase. The control reactors outperformed the reactors where inoculum was added on top or mixed in with the digestate. The quality of the matured compost from all the reactors in both studies met or exceeded required specifications. The stability and maturity of the composts were compared to Rocky Mountain Region Classification tables as well as the SMI range. In each case, the analytes measured were below the suggested limits in the classification table and most fell in the "finished compost" range on the SMI scale. The values of the major nutrients assessed were of satisfactory contents as to be useful for land application. This study seeks to encourage the process of MSAD on feedlots with HSCM in arid to semi-arid regions by demonstrating the usefulness of the by-products achieved from the process. Methane gas produced in the anaerobic phase is a valuable form of renewable energy that can be used onsite. A mature compost product meeting Class 1 Compost/ Soil Amendment Classification standards can be used onsite or sold for a variety of applications. By generating methane and beginning the composting process in the same LBR, solids are further reduced, weight is minimized and the material is more stable for transportation and storage.
Open Access
An advanced decentralized wastewater management planning study and demonstration project for the CSU Foothills Campus
(Colorado State University. Libraries, 2010) Gallagher, Neal Thomas, author; Sharvelle, Sybil, advisor; Roesner, Larry A., committee member; Goemans, Christopher G., committee member
Expansion of development on the Colorado State University's (CSU) Foothills Campus has required examination of alternative methods to manage wastewater produced within the campus. This work builds off previous work which demonstrated that reuse of graywater and treated blackwater effluent could greatly reduce the cost of supplying wastewater treatment for the Foothills Campus (Criswell & Roesner 2005). The objective of this work was to provide insight into innovative decentralized wastewater technologies and management techniques to lay the groundwork for planning and design of optimal decentralized wastewater treatment architecture for the Colorado State University Foothills Campus. This objective was met through a planning study and a demonstration project examining anaerobic digestion of blackwater. A planning study was performed providing four potential scenarios for management of wastewater on the Foothills Campus. Source separation was recommended for proposed development, however combined plumbing in existing development was left unaltered. Four different wastewater streams were identified by type and level of treatment necessary: blackwater, graywater, laboratory process water, and laboratory sink water. Anaerobic digestion was recommended for primary treatment of blackwater because of the renewable energy (methane biogas) and nutrient rich effluent which are produced. Constructed wetland treatment was recommended for graywater and laboratory process water, to provide a source of reusable water for irrigation or toilet flushing. Technical feasibility of treatment of graywater from a campus setting in a constructed wetland has been previously examined, showing substantial levels of treatment. Technical feasibility of anaerobic digestion of blackwater from a campus setting is further examined in this study through a 108 L upflow anaerobic sludge blanket (UASB) treating raw blackwater from a building on the Foothills Campus. Reactor operational OLR varied between 0.21-0.39 kg COD/m3•d and HRT varied between 2.6-4.0 days during the study period. Total reactor operational time was 108 days at an effluent temperature of 28°C. Substantial removal of COD (72%), TSS & VSS (95%), and indicator organisms (1.4 log E. coli & 1.1 log fecal coliforms) was achieved over the study period. Effluent containing 79 mg/L dissolved ammonia nitrogen showed potential for use as fertilizer. Methane biogas produced during digestion (137 L CH4/kg CODinput) provided potential as a source of renewable energy. Overall performance of the UASB was sufficient for pretreatment of Foothills Campus blackwater. However, further examination of effluent, solids, and biogas reuse potential is necessary to determine supplementary treatment requirements and desired applications for extracted resources.
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 nutrient removal at the Drake Water Reclamation Facility
(Colorado State University. Libraries, 2016) Mueller, Lincoln H., author; Sharvelle, Sybil, advisor; Arabi, Mazdak, committee member; Rice, Doug, committee member
Since the 1960’s, the Federal Government through the United States Environmental Protection Agency (USEPA) has been working to create and enforce regulations to protect and counteract the degradation experienced in the nation’s waterways due to increased nutrient loading (primarily phosphorus and nitrogen). The eutrophication caused by excess levels of these nutrients is not only an aesthetic issue, but is toxic to aquatic life and can also create issues detrimental to human health. In 2007, the Colorado Department of Public Health and Environment began working on new nutrient regulations for state dischargers, particularly larger Publicly Owned Treatment Works (POTWs) like the City of Fort Collins and its two wastewater treatment plants, Mulberry Water Reclamation Facility (MWRF) and Drake Water Reclamation Facility (DWRF). Since 2008, The City of Fort Collins has been upgrading its secondary treatment systems to Biological Nutrient Removal (BNR) in preparation for National Pollutant Discharge Elimination System (NPDES) permit compliance in 2020. Early in the design process, it was determined that DWRF suffered from a limitation in influent carbon for adequate nutrient removal and carbon addition would need to be considered. The City analyzed various local carbon sources and has been working to determine the viability of beer waste from local breweries as a viable carbon source. The overarching goal of this work is to evaluate the current nutrient removal efforts at DWRF to help determine if adjustments are required to the wastewater treatment Master Plan to consistently meet Colorado’s Regulation 85 nutrient discharge limits. This study included monitoring of nutrient water quality values at specific points in the treatment system while adding beer waste at varying flow rates and durations to determine its effect on the system. Different automated control strategies were tested using several dosage schemes including Oxidation Reduction Potential (ORP) values. Finally, water quality data was analyzed and compared alongside historical nitrogen and phosphorus values to evaluate the effects of the beer waste addition to effluent quality and plant removal performance. The initial values for effluent total inorganic nitrogen showed promise, averaging 9.79 mg/L in comparison to 12.05 mg/L when beer waste was not added. However, a mass balance comparison with influent nitrogen values showed no significant difference in BNR process performance for nitrogen with the beer addition. Effluent phosphorus values averaged 2.24 mg/L-P which was slightly lower than without beer waste addition (2.42 mg/L), but not considered a statistically significant decrease. During the study, an observation was made that adjusting time-of-day and flowrate of the dewatering centrate return significantly decreased effluent phosphorus concentrations down to 1.1 mg/L, significantly lower than P concentrations without beer addition (p < 0.05). An analysis of phosphorus removal at DWRF also highlighted the historical improvement of phosphorus removal as BNR improvements are brought on-line, even though the required effluent limits required by Regulation 85 have not been achieved yet. Overall, carbon addition via beer waste has shown to have positive impact on DWRF’s ability to remove nutrients. Lower effluent concentrations of nitrogen were achieved when beer waste was added to DWRF and lower effluent P concentrations were also achieved as long as centrate return flow was controlled. Additional study is required for long-term control of centrate return flows which may include the analysis of side-stream treatment solutions. Additional analysis to determine the role of beer waste addition independent of centrate flow returns is also recommended.
Open Access
Assessing benefits and consequences of water conservation and fit for purpose water systems
(Colorado State University. Libraries, 2020) Patel, Saloni N., author; Sharvelle, Sybil, advisor; Arabi, Mazdak, committee member; Nelson, Tracy, committee member
Rising population accompanied with urbanization is increasingly challenging the resilience and capacity of traditional water management system. The migration of the human population to urban areas has given birth to sprawling new developments and re-developments which poses serious challenges to conserve and manage water. Water managers and policy makers are faced with an arduous task to enhance conventional water management systems by implementing Integrated Urban Water Management and hybrid centralized-decentralized systems. To enable informed decisions on water demand management strategies based on water demand reduction, cost, energy savings, etc., understanding benefits and consequences is of utmost importance. Benefits and consequences of water conservation and reuse are seldom considered while making quantitative decisions, mainly due to lack of supporting data or methodology. This research fills this knowledge gap by providing methodology on identifying, developing and quantifying a set of indicators that measure performance for water demand reduction strategies including conservation strategies and use of alternate water sources (i.e., fit for purpose water) in triple bottom line (TBL) categories. Literature review, triple bottom line (TBL) evaluation, and Multi-Criteria Decision Analyses (MCDA) were used to develop a set of indicators to assess water demand reduction strategies. To demonstrate the use of indicators to inform water management decisions, TBL indicator analysis was performed on Globeville-Elyria-Swansea (GES) community in Denver, Colorado using Integrated Urban Water Model (IUWM). The results from TBL indicator analysis suggests that use of stormwater performed well across all indicator categories, it achieved high water demand reduction, was energy efficient and also publicly accepted. Further cost comparison and MCDA scores revealed, Stormwater for Potable & Irrigation as the top performing end use. Use of stormwater as a supply has potential for large reduction in demand for traditional supplies and also offers notable social and environmental benefits. Water rights issues and costs remain barriers for adoption of this practice that need to be overcome to realize the benefits.
Open Access
Assessing tradeoffs of urban water demand reduction strategies
(Colorado State University. Libraries, 2019) Neale, Michael R., author; Arabi, Mazdak, advisor; Sharvelle, Sybil, advisor; Goemans, Christopher, committee member
In many cities across the World, traditional sources of potable water supply can become susceptible to shortage due to increased water demands from rapid urbanization and more frequent and extreme drought conditions. Understanding impacts of city-scale conservation and water reuse is important for water managers to implement cost effective water saving strategies and develop resilient municipal water systems. Innovative water reuse systems are becoming more cost effective, technologically viable and socially accepted. However, there is still a need for comparative assessment of alternative sources; graywater, stormwater and wastewater use along with indoor and outdoor conservation, implemented at the municipal scale. This study applies the Integrated Urban Water Model (IUWM) to three U.S. cities; Denver, CO; Miami, FL; and Tucson, AZ. We assess the tradeoffs between cost and water savings for a range of solutions composed of up to three strategies; to understand interactions between strategies and their performance under the influence of local precipitation, population density and land cover. A global sensitivity analysis method was used to fit and test model parameters to historical water use in each city. Alternative source and conservation strategies available in IUWM were simulated to quantify annual water savings. Alternative source strategies simulate collection of graywater, stormwater and wastewater to supplement demands for toilet flushing, landscape irrigation and potable supply. A non-dominated sorting function was applied that minimizes annual demand and total annualized cost to identify optimal strategies. Results show discrete strategy performance in demand reduction between cities influenced by local climate conditions, land cover and population density. Strategies that include use of stormwater can achieve highest demand reduction in Miami, where precipitation and impervious area is large resulting in larger generation of stormwater compared to other study cities. Indoor conservation was frequently part of optimal solutions in Tucson, where indoor water use is higher per capita compared to other study cities. The top performing strategies overall in terms of water savings and total cost were found to be efficient irrigation systems and stormwater for irrigation. While use of stormwater achieves large demand reduction relative to other strategies, it only occurred in non-dominated solutions that were characterized by higher cost. This strategy can be very effective for demand reduction, but is also costly. On the contrary, efficient irrigation systems are frequently part of low-cost solutions across all three study cities. Overall, this study introduces a framework for assessing cost and efficacy of water conservation and reuse strategies across regions. Results identify optimal strategies that can meet a range of demand reduction targets and stay within financial constraints.
Embargo
Cattle manure characteristics in relation to manure accumulation period and seasonal impacts in the intermountain west
(Colorado State University. Libraries, 2023) Bhowmik, Priya R., author; Sharvelle, Sybil, advisor; De Long, Susan, committee member; Olsen, Daniel, committee member
Anaerobic digestion (AD) of organic waste has been studied and implemented in practice more recently than ever. AD is used to produce biogas, which mainly consists of methane gas that has multiple purposes. Arguably the most important purpose methane gas has is that it is a renewable energy source. Organic waste that can serve as feedstock for AD ranges from food waste to animal waste, including manure. There are limited application of AD technology to process beef cattle manure compared to other manure sources due to factors such as method of collection processes (i.e., scraped on dry lots) and inconsistent methane gas produced due to varied conditions. This study focuses on beef cattle manure from the intermountain west, home to many cattle feedlots producing millions of tons of manure a year. Beef cattle feedlots pens typically have a base of compacted manure with no roof covering the pen. With no roof over the beef cattle feedlots and low collection frequency, the manure is exposed to seasonal change with varying weather conditions and often contains low water content and high inorganic material compared to other animal feeding operation manure. To improve the methane production of beef cattle manure in AD processes, more information is needed on the quality of beef cattle manure over varying collection frequency and seasons. The objective of this research is to determine biochemical methane potential (BMP) for differing accumulation time periods and seasonal impact. Four sample collections were conducted at one concentrated animal feeding operation (CAFO) from different months with different seasonal effects. For each sample collection, different manure accumulation periods were selected ranging from 7 to 90-day old manure. For each accumulation period, three cattle pens were selected based on the similar number of cattle and same feed. All manure was collected from each pen and was weighed with subsequent testing for characteristics. Based on the total solids (TS) from each pen in each manure accumulation period the composite sample was created for the manure accumulation period which was tested for BMP. A second manure collection technique was used due to complications with collecting lower manure accumulation periods with the first collection technique such as an uneven surface of the pen. The second technique applied land surveying one singular pen for a 10- and 20-day manure accumulation period to attempt to only collect newly deposited manure over the accumulation period. The BMP data is expressed as the volume of methane (CH4) produced per unit of volatile solids (VS) added, typically represented as mL CH4/ g VS feedstock. VS is the portion of the material that is organic and for this study in terms of volatile mass per dry mass. The sample collections from this study BMP results ranged from 200-276 mL CH4/ g VS feedstock. A literature review was conducted comparing over 13 studies that tested beef manure in AD. Results from this study were above the average of the literature review which was 160 mL CH4/ g VS feedstock. One of the sample collections occurred in May, which was the only data which represented a parallel trend between manure accumulation periods and BMP results, with BMP decreasing with longer accumulation periods. The May sample collection produced the highest measured ultimate BMP and was considered the most precise manure collection. Statically different trends were not observed for samples collected over seasons, leading to inconclusive results on seasonal impacts on BMP. The land surveying technique for manure collection resulted in variable quality manure, which emphasized the struggle of replication of manure collected and the possibility of obtaining only the desired manure accumulation period without obtaining any of the manure pad. Overall, results indicated the potential for increased methane production potential for more frequently collected manure at beef feedlots. However, the study also indicated that more frequent collection of only freshly deposited manure would be difficult to implement in practice.
Open Access
Characterization of urban water use and performance evaluation of conservation practices using the Integrated Urban Water Model in São Paulo, Brazil
(Colorado State University. Libraries, 2018) Batista, Giovana das Gracas, author; Arabi, Mazdak, advisor; Sharvelle, Sybil, advisor; Dozier, Andre, committee member; Goemans, Christopher, committee member
Increasing urban population around the globe has intensified the need for water, food and energy. The residential sector is responsible for the highest water use in urban settings. Understanding the factors affecting water use helps to improve management strategies, incentivize conservation practices, develop public educational events, feed demand forecasting models and support policy creation. Modelling urban water demand in the long-term is a complex process because of incorporation of multiple dynamic components in the urban-environment system. The Integrated Urban Water Model – IUWM – offers capabilities of long-term modelling by using a mass-balance approach for urban water demand predictions and potential demand reductions assessment. A combination of climate anomalies, water resources management practices over the years and watershed conservation contributed to the water shortage in Southeastern Brazil in 2014-2015. In the city of São Paulo, the shortage was worsened by drops in reservoir levels, rise in water use patterns and in number of inhabitants, and the historical tendency to neglect local water sources. Residential water demand, which accounts for 84% of the total water use, faced compulsory reductions through behavioral changes and reuse of graywater and roof runoff harvesting. The goals of this study are to apply IUWM to the city of São Paulo to quantify savings produced by graywater and roof runoff use and to evaluate the potential of conservation practices for demand reduction. The first part of the study focuses on exploring differences in water demand patterns under shortage conditions using a water use time-series from 2013-2017. In this part, IWUM is trained to estimate indoor and outdoor demand through calibration procedures. Determinants of water demand are also investigated through a multiple linear regression, which identified household size and socioeconomic variables as having a significant effect in water use. The second portion focuses on applying IUWM to evaluate reductions during the shortage and performance of graywater, stormwater, roof runoff harvesting and effluent reuse for potable and non-potable purposes. Climate change was added to assess shifts in performances of conservation practices due to future reductions in precipitation. Lastly, a comparison of maximum potential and benefits of fit-for-purpose technology adoption is done using a cost-benefit matrix. The matrix was adapted for required treatment representing cost and percentage reductions in water demand as benefit. The results of this work support decision-making with respect to conservation practices adoption by enhancing the list of options to manage water demand, especially during shortage conditions. Ultimately, these results can encourage development of water reuse policies in Brazil.
Open Access
Considerations for implementing source separation and treatment of urine, graywater, and blackwater
(Colorado State University. Libraries, 2015) Fewless, Kimberly LeMonde, author; Sharvelle, Sybil, advisor; Bledsoe, Brian, committee member; Goemans, Chris, committee member
Source separation integrated with decentralized wastewater treatment offers the possibility of recovering nutrients, reducing release of micropollutants to the environment, and increasing water recycling more efficiently than centralized wastewater treatment. Nutrient effluent discharge limits and guidelines for wastewater treatment plants are becoming stricter, and nutrient removal or recovery is very costly for the large volumes present. This is driving innovation in wastewater treatment. Three waste streams are identified for potential source separation and treatment: urine, graywater (non-kitchen sinks, showers/bath, and laundry), and blackwater (feces and kitchen wastewater). Urine is only 1% of the domestic wastewater stream, but contains 50-80% of the nutrients (nitrogen, phosphorus, and potassium) and the majority of pharmaceuticals and hormones. Blackwater has high organic and nutrient content, solids, and pathogens, and carries the remaining pharmaceutical/hormone residues. Graywater is the largest contributor to total volume but is the least contaminated of the three streams (low in nutrients and pathogens, but contains detergents and personal care products). In the absence of kitchen wastewater, graywater is also low in organic content. If these streams are separated at the source, maximum reuse of water can be achieved with minimal treatment (e.g. graywater). More importantly, avoiding dilution of nutrients and pharmaceuticals/hormones allows for more advanced treatment without excess cost. A literature review led to the conclusion that the best options for urine treatment are struvite precipitation for phosphorus recovery and ammonia stripping for nitrogen recovery. Anaerobic digestion is ideal for blackwater and constructed wetlands can be used for graywater treatment. A neighborhood system of 500-1000 homes with decentralized treatment of urine, graywater, and blackwater is proposed. Almost complete recovery of nutrients could be achieved from urine, graywater could be treated and “locally” recycled, and energy and nutrients could be recovered from blackwater. A wastewater treatment system combining these components has not yet been tested in a pilot project; however, the individual treatment systems have been operated in pilot projects (or at larger scales) with similar waste streams. Modification of regulatory framework will be necessary to accommodate water reuse and effluent regulations at the proposed decentralized scale. Although nutrient reuse is a goal in the proposed system, farmer and consumer acceptance in the U.S. are unknown, but critical. Technical obstacles to implementation include improving urine diversion toilets and treatment systems (primarily decreasing maintenance and increasing automation), managing urine scale (spontaneous precipitation in pipes), avoiding or capturing volatilized ammonia in urine transport, and better characterizing waste streams for treatment optimization. Research and development should focus on decreasing maintenance of urine diversion components and increasing automation. It is also necessary to better define influent quality and effluent goals and to optimize treatment systems for the proposed configuration. The waste stream produced from urine treatment also needs consideration, as it is likely to by highly concentrated with pharmaceuticals. A pilot project in the U.S. is recommended to resolve technical issues. A preliminary review of costs reveals that, as is typically the case with new technologies, urine diversion toilets and struvite precipitation reactors have high investment and operational costs. Despite this, early estimates indicate that urine diversion systems are less costly than adding nutrient removal in wastewater treatment plants. In addition, the high costs of urine diversion systems are largely due to maintenance requirements and economies of scale (aspects that will change with research and development). In moving forward, it will be beneficial to conduct an economic analysis of greater breadth, with consideration of water reuse, energy use/carbon footprint, cost of fertilizer production, potential revenue of recovered nutrients, and economic externalities. It is also important to consider the reality of transition: that unless conventional wastewater treatment becomes more expensive (due to nutrient regulations) or homeowners are willing to cover the extra cost of a decentralized system with urine diversion, developers/homeowners are likely to choose tapping into the current system. Although technical issues are pressing and infrastructure requirements are extensive for the proposed decentralized system, the technical, social, and regulatory issues are not insurmountable. The potential in improved treatment (nutrient and micropollutant removal), energy generation and increased water recycling suggests moving forward with research and development in the U.S., including a pilot project.
Open Access
Decision support for anaerobic digestion installations at cattle operations in Colorado
(Colorado State University. Libraries, 2013) Lasker, Jeff, author; Sharvelle, Sybil, advisor; Fontane, Darrell, committee member; Keske, Catherine, committee member
Anaerobic digestion is a biological process used to convert organic wastes into a stable product while also producing methane for energy generation. The end product can be land applied without adverse environmental effects. The implementation possibilities of anaerobic digestion in Colorado have great potential with an estimated 14 million dollars in potential energy generation revenue. Anaerobic digestion systems in Colorado can provide great benefits for primarily in the cost savings associated with removal of manure and other biological waste products. The objective of this project was to develop web-based decision-making tools with a step-by-step guide for producers and their advisers to utilize as they consider installation of bioenergy conversion technology. The start of the project began with a field study, where manure samples were collected and analyzed for specific characteristics. Performance and applicability of anaerobic digesters varies greatly among individual farms, particularly in terms of gas production, moisture content, implementation, practicality and cost. The tool provides producers with a preliminary assessment of the feasibility of anaerobic digestion on their farm. The decision tool contains general information about anaerobic digestion systems, provides estimates of methane and electricity production, provides guidance on economic feasibility, selection of a most appropriate technology, and selection of a technology provider. Long term goals of the project include increasing adoption of animal waste to energy conversion technology and to improve the ability of producers to maintain operation of technologies post-installation.
Open Access
Development of a cost effective and energy efficient treatment system for graywater reuse for toilet flushing at the multi-residential scale
(Colorado State University. Libraries, 2012) Hodgson, Brock, author; Sharvelle, Sybil, advisor; Roesner, Larry, committee member; Goemans, Christopher, committee member
A growing population increases water demand in many metropolitan areas resulting in the need for projects, like graywater reuse, that free up water supply or decrease water consumption. Plumbing for graywater collection from showers and bathroom sinks has been separated from blackwater collection in 14, two-person units at a residence hall at Colorado State University. Treatment technologies were evaluated for the ability to provide safe and cost effective onsite reuse of graywater for toilet flushing. The goal is to develop a system with low use of energy and consumables capable of treating graywater to a quality safe for toilet flushing. The system analyzed filtration utilizing coarse, sand (20-40 microns), or cartridge (100 microns) filtration and the disinfection potential of ultraviolet (UV) with hydrogen peroxide (H2O2), chlorine, UV with chlorine as a residual, or ozonation with chlorine as a residual. Disinfection efficacy was determined by measuring general water chemistry parameters in addition to concentration of E. coli and total coliforms. The influent E. coli averaged 10 2.7±1.1 CFU/100mL and total coliform averaged 10 7.9±1.2 CFU/100mL. Effluent E. coli was reduced to non-detectable concentrations for UV combined with H2O2 and chlorine, but only chlorine measured non-detectable concentrations of total coliform. At the tested doses, ozone combined with chlorine and UV combined with chlorine resulted in limited or no removal of E. coli and total coliforms. Higher doses may prove to provide more efficient disinfection but require more expensive equipment and may impact the projects feasibility. Based on data collected, chlorine appears to be a better approach for disinfection of graywater. None of the disinfectants significantly affected graywater chemistry, but all reduced odors with the exception of UV. There was no significant change of water chemistry as a result of coarse or cartridge filtration. Sand filtration significantly reduced turbidity, total suspended solids (TSS), total organic carbon (TOC) and biochemical oxygen demand (BOD5) by 13±11%, 37±12%, 31±17% and 21±9% respectively. Despite the decrease of TSS and TOC, the sand filter resulted in an increase chlorine demand. As a result, it was concluded that the most effective treatment alternative is incorporation of coarse filtration followed by chlorine disinfection. The health and environmental concerns associated with chlorine disinfection can be minimized by utilizing ammonia in graywater to favor monochloramine formation which results in a smaller dose. Additionally, the influent specific UV absorbance of 1.1±0.6 indicates reduced risk of disinfection by-product formation. The cost, including capital and operation, of implementing various filtration and disinfection approaches along with the total life-cycle project cost at various system sizes were evaluated. At the residence hall scale, the most cost effective disinfection approaches include application of liquid chlorine, ultraviolet with chlorine as a residual, and small-scale ozonation with chlorine as a residual. The cost of the hydrogen peroxide dose rendered its use infeasible. The cost effective filtration approaches were coarse, sand (20-40 microns), and cartridge (100 microns) and the associated capital for each filter did not have a large impact on the life-cycle cost. Graywater reuse for toilet flushing proved financially beneficial particularly in regions with high domestic water costs and at system sizes that reuse ≥1,000 gpd. These projects can be financially feasible and have low payback periods in addition to indoor water use reduction.
Open Access
Development of a decision support system for integrated urban water resources management
(Colorado State University. Libraries, 2011) Reichel, Bradley I., author; Sharvelle, Sybil, advisor; Roesner, Larry, advisor; Glick, Scott, committee member
The challenges of addressing the needs of aging water and wastewater infrastructure require new management approaches. Traditional municipal water management practices may not be the most cost effective solutions. Savings may be realized through the adoption of new integrated water management concepts such as treated wastewater effluent and/or graywater reuse, rainfall harvesting, etc. Determining which water management practices are best suited to a particular urban area can be a difficult task as costs, climate, and population characteristics vary across regions. The Integrated Urban Water Model (IUWM) has been developed by the Urban Water Center at Colorado State University to aid urban planners and utility managers in the assessment of which water management practices may prove most beneficial to their communities. These practices include: indoor conservation, irrigation conservation, wastewater treatment plant (WWTP) reuse for irrigation, graywater reuse for toilet flushing and irrigation, and stormwater capture reuse for irrigation. The model is native to the Windows operating environment and includes a graphical user interface through which the user can easily add information about the region and assess the potential benefits of the included water management practices. A case study application of the model to five cities in different climatological regions of the United States is included in the report. The case study serves as both an example of how the application may be used and demonstrates its capabilities. The results of the case study reveal that hydrologic conditions impact the effectiveness of selected water management practices.
Open Access
Effect of graywater irrigation on soil quality and fate and transport of surfactants in soil
(Colorado State University. Libraries, 2012) Negahban Azar, Masoud, author; Sharvelle, Sybil, advisor; Carlson, Kenneth, committee member; Stromberger, Mary, committee member; Durnford, Deanna, committee member
While interest in and adoption of graywater reuse for irrigation has rapidly grown in recent years, little is known about the long-term effects of graywater irrigation. Concerns exist in relation to the presence of pathogenic organisms, fate of personal care products, and accumulation of salts. The purpose of this research was to evaluate the long-term effects of graywater irrigation to soil quality. The specific objectives were to evaluate the effects of graywater application on physical and chemical quality of soil, including surfactants, salts and boron accumulation, organic matter leaching and soil hydrodynamic properties in real environment in the field, in controlled environment in the greenhouse and column studies. In addition, fate and transport of surfactants in soil were investigated including how surfactant characteristics impacts mobility in soil of varying types. Graywater irrigation was found to significantly increase sodium in soil at households with graywater systems in place for more than five years; however SAR was not high enough in any of the sampling locations to raise concern about soil quality or plant health. There is a potential for salts, N, and B to leach through soil when graywater is applied for irrigation. A portion of the applied N is assimilated by plants, but leaching of N was observed. Graywater irrigation was also found to significantly increase surfactants in soil. Surfactants mainly accumulated in surface soil (0-15 cm) compared to depth soil. While surfactants have high sorption capacity due to their hydrophobic characteristics, they can be transported through soil if a large amount of water is applied. Among the surfactants measured in this study, AS and AES had the highest mobility. Mobility of surfactants in soil decreased when their number of ethoxylated groups increased. Adding organic matter to the soil increased sorption capacity of soil, as a result, more surfactants retained in the soil columns. Antimicrobials, including triclosan and triclocarban were detected in graywater irrigated areas only in surface soil samples, but not freshwater irrigated areas.
Open Access
Enhancement of liquid flow through a leach bed reactor for anaerobic digestion of high solids cattle manure
(Colorado State University. Libraries, 2017) Wu, Rongxi, author; Sharvelle, Sybil, advisor; De Long, Susan, committee member; Butters, Greg, committee member
Due to animal production waste increases in Colorado, anaerobic digestion (AD) has become increasingly considered as a technology to convert organic solid waste (OSW) into renewable energy. The arid climate with water resource limitation in Colorado results in high solids cattle manure (HSCM) production, containing between 50% and 90% total solids (TS). Conventional AD for animal manure is best option to treat manure with less than 20% TS, but limited feasibility for conventional anaerobic digesters treats manure in Colorado. The multi-stage anaerobic digester (MSAD) investigated in this study can digest HSCM. An integral part of the MSAD is the Leach Bed Reactor (LBR), which is loaded with HSCM (up to 90% TS). A small quantity of water percolates into the LBR and is recirculated through the LBR where hydrolysis occurs until a large amount of organic material is solubilized into the leachate. A review of the literature has indicated that clogging can be an issue in operation of manure LBRs. Since sustaining liquid flow through LBRs can be a challenge, research was conducted to better understand how to use this technology to treat HSCM. The objectives of this research were to 1) assess the performance of the LBR component of the MSAD technology with different top layer materials and flow regimes to enhance duration of sustained flow, 2) assess the ability of varying top layer materials and flow regimes to enhance hydraulic conductivity of the manure bed in the LBR to maximize hydrolysis in the LBR. For this study, downward flow and upward flow LBR configuration experiments were conducted. The combination of a sand layer on top of the manure beds and an improved top filter for the LBR was added in the upward flow LBR configuration. HSCM samples from each stage of the experiment were analyzed for TS, fixed solids (FS), and volatile solids (VS), and the leachate samples were analyzed for chemical oxygen demand (COD). The leachate outflow rate and column pressure head were also measured daily. Due to failure of all downward flow experiments, the upward flow LBR configuration was evaluated. The clogging issues and leachate flow through the LBR improved by changing to the upward flow LBR configuration. The average operation time of the upward flow experiment was prolonged to 21 days comparing with downward flow experiment, which operated for an average of only 7 days. The percentage reduction of VS in upward flow experiments was on average above 40% indicating successful hydrolysis in the LBRs, comparable to VS reduction observed by other researchers (Uke and Stentiford, 2012). The COD concentration of the upward flow experiments started at an average of 45 g COD/ L and approached the LST's COD concentration of 10 g COD/L at day 10. This indicates that the MSAD was effectively degrading the HSCM throughout the batch digestion period. The constant pressure head of upward flow experiments indicated that no pressure built up inside the LBRs resulting in improved flow through the manure in these systems. In summary, this research showed that the upward flow LBR configuration with the combination of a sand layer on top of the manure bed and improved top cap filter can sustain leachate flow through the LBR for 21 days of operation.
Open Access
Enhancing hydraulic performance of a multi-stage anaerobic digester for high solids cattle manure
(Colorado State University. Libraries, 2019) Young, Kadin Catlin, author; Sharvelle, Sybil, advisor; De Long, Susan, committee member; Olsen, Daniel, committee member
Anaerobic digestion is an attractive technology for waste handling because it converts low value waste material into energy and other useful products while performing necessary treatment for proper waste disposal. Conventional anaerobic digestion technology, however, has been met with many economic challenges when being applied to high solids substrate such as dry-lot cattle manure. In Colorado and the rest of the arid west, feedlot practices and dry climate combine to form a waste product that is very high in total solids (TS) content, from 50% up to 90% TS. Since the most common conventional digestion practices typically can only treat wastes up to a maximum of 15% TS, other options must be considered to digest this abundant waste product and convert it to a valuable resource. Research at Colorado State University has led to the development of an innovative multi-stage anaerobic digester (MSAD) technology capable of digesting high solids content waste with very low water addition. The CSU MSAD has demonstrated the ability to successfully digest high solids content waste like that found at the many Colorado feedlots. This system differs from conventional technology in that hydrolysis takes place in one reactor and methane generation takes place in a separate high rate digester. The development of the MSAD for digestion of high solids cattle manure leads to the promising opportunity for valorization of a prevalent waste product in Colorado to create valuable products including methane biogas, compost, and fertilizers. The present research aims to advance the technology by assessing the performance of the MSAD running in a fully linked configuration including each of its individual components: the Upflow Solid-State Hydrolysis Reactor (USSHR), the Leachate Feed Tank (LFT), and the Fixed Film Reactor (FFR). A fully functional Central Leachate Processing System (CLPS) was constructed to demonstrate the technology, to facilitate column scale studies, and to link with the prototype USSHR (P-USSHR) to enable the evaluation of an improved liquid distribution system. The MSAD was constructed at column scale to evaluate the impact on organic leaching potential of varying hydraulic loading rate (HLR) through the USSHR using HLRs of 20, 41, and 75 cm/day for 16-day cycles. This experiment was the first successful demonstration of a fully linked MSAD system using cattle manure as feedstock. It was found that the higher HLR of 75 cm/day yields 25% more COD leached over the 16-day operating period than the two lower loading rates. Additionally, it was found that the P-USSHR achieved notable improvements over the previous operation in hydraulic distribution through the reactor and therefore improved digestion performance and volatile solids destruction, though areas for further improvement were noted.
Open Access
Evaluation of a trickle flow leach bed reactor for anaerobic digestion of high solids cattle manure
(Colorado State University. Libraries, 2013) Hanif Abdul Karim, Asma, author; Sharvelle, Sybil, advisor; Carlson, Kenneth, committee member; Davis, Jessica, committee member
Anaerobic digestion (AD) of cattle manure from feedlots and dairies is of increasing interest in Colorado due to its abundant availability. Colorado is the one of the highest producer of high solids cattle manure (HSCM) in the United States. Despite the available resources, Colorado currently has only one operational anaerobic digester treating manure (AgSTAR EPA 2011), which is located at a hog farm in Lamar. Arid climate and limited water resources in Colorado render the implementation of high water demanding conventional AD processes. Studies to date have proposed high solids AD systems capable of digesting organic solid waste (OSW) not more than 40% total solids (TS). Lab tests have shown that HSCM produced in Greeley (Colorado) has an average of 89.6% TS. Multi-stage leach bed reactor (MSLBR) system proposed in the current study is capable of handling HSCM of up to 90% TS. In this system, hydrolysis and methanogenesis are carried out in separate reactors for the optimization of each stage. Hydrolysis is carried out in a trickle flow leach bed reactor (TFLBR) and methanogenesis is carried out in a high rate anaerobic digester (HRAD) like an upflow anaerobic sludge blanket (UASB) reactor or a fixed film reactor. Since leach bed reactors (LBRs) are high solids reactors, studies have indicated clogging issues in LBRs handling 26% TS. Since TFLBRs are subjected to hydrolyze upto 90% TS, obtaining hydraulic flow through the reactor is a challenge. The objective of this research is to (a) ensure good hydraulic flow through the TFLBRs and (b) evaluate and optimize the performance of the TFLBR to effectively hydrolyze the HSCM. The system was operated as a batch process with a hydraulic retention time (HRT) of 42 days without leachate recirculation. A layer of sand was added as dispersion media on top of the manure bed in the TFLBRs. This promoted good hydraulic flow through the reactor eliminating clogging issues. Organic leaching potential of a single pass (without leachate recirculation) TFLBR configuration was evaluated in terms of chemical oxygen demand (COD). Manure is naturally rich in nutrients essential for microbial growth in AD. In a typical MSLBR system, the TFLBRs are subjected to leachate recirculation, conserving the essential nutrients in the system. However, in this single pass system, the leachate removal would flush out the nutrients in the TFLBRs over time. So, nutrient solution was added to the TFLBRs to provide a constant supply of essential nutrients in the reactors for the purpose of this study and would not be necessary in a leachate recirculated TFLBR. A comparison between nutrient dosed and non-nutrient dosed TFLBRs was performed. The non-nutrient dosed and nutrient dosed TFLBRs indicated a COD reduction of approximately 66.3% and 73.5% respectively, in total in terms of dry mass. A total reduction in volatile solids (VS) of approximately 46.3% and 44.7% was observed in the non-nutrient dosed and nutrient dosed TFLBRs, respectively. Biochemical methane potential (BCMP) tests indicated a CH4 potential of approximately 0.17 L CH4/g COD leached and 0.13 L CH4/g COD leached from the non-nutrient dosed and nutrient dosed TFLBRs, respectively. Concentration of inorganics leached from the TFLBR was monitored periodically.
Open Access
Evaluation of cost effective approaches for nutrient removal in urban stormwater and wastewater: City of Fort Collins case study
(Colorado State University. Libraries, 2015) Breidt, Sarah, author; Sharvelle, Sybil, advisor; Roesner, Larry, committee member; Goemans, Chris, committee member
To respond to pending regulation that affects effluent nitrogen and phosphorus standards from urban watersheds, this study compares existing nutrient discharges from wastewater and stormwater sources in Fort Collins, Colorado and evaluates the benefits and costs of nutrient removal strategies identified in both sectors as a guide to urban planners. Six alternative wastewater advanced nutrient removal technologies were modeled in BioWin® to be integrated with the existing modified Bardenpho unit. Approximately 1,500 stormwater control measures (SCMs) are implemented in Fort Collins at present; however, not all provide water quality treatment. Two alternative stormwater scenarios were evaluated using the Simple Method and include: 1) retrofitting existing flood control SCMs to provide treatment, and 2) implementing SCMs to treat runoff from currently untreated impervious areas. Treatment level, environmental impacts, and 20-year lifecycle costs were determined for all alternatives and compared within a multi-criterion decision analysis (MCDA). Existing wastewater discharges of nitrogen and phosphorus are 2.0 and 1.5 times larger than those from stormwater, respectively. Removal efficiencies from these discharge nutrient levels were found to be between 7.5% and 30% for wastewater and 20% and 35% for stormwater. Although wastewater alternatives had large ranges of potential costs, all were determined to be more cost effective ($/lb. removal) than the stormwater scenarios. Struvite precipitation in all MCDA scenarios is the most advantageous alternative, followed by ammonia stripping and extended detention basin (EDB) retrofits.