Browsing by Author "Sharvelle, Sybil E., advisor"
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Item Open Access Free water surface and horizontal subsurface flow constructed wetlands: a comparison of performance in treating domestic graywater(Colorado State University. Libraries, 2012) Hollowed, Margaret Ellen, author; Sharvelle, Sybil E., advisor; Roesner, Larry A., committee member; Stromberger, Mary, committee memberCommunities throughout the United States and abroad are seeking innovative approaches to sustaining their freshwater resources. Graywater reuse for non-potable demands is gaining popularity because it allows for the reuse of minimally contaminated wash water, generated and treated on site. Graywater is defined as any wastewater generated at the home or office including wastewater from the laundry, shower, and bathroom sinks but excluding water from the toilets, kitchen sinks, and dishwasher. When compared to other wastewater generated in the home, graywater is contaminated with lower concentrations of organics, solids, nutrients, and pathogens. These characteristics make the water suitable for reuse with negligible treatment when compared to other domestic wastewater sources. Graywater reuse for non-potable demands reduces the demand for treated water and preserves source waters. One method of treating graywater at a community scale for irrigation reuse is constructed wetlands. Despite widespread interest in this innovative approach, limited guidance is available on the design and operation of constructed wetlands specific to graywater treatment. The foremost objective of this research was to compare the performance of a free water surface constructed wetland (FWS) to a horizontal subsurface constructed wetland (SF) for graywater treatment and to assess their ability to meet water quality standards for surface discharge and reuse. This was done by comparison of percent (%) mass removal rates and requisite surface areas (SA) based on determined removal rates ( k ). Aerial loading rates were compared to EPA suggested aerial loading rates in an attempt to provide recommendations for target effluent concentrations. Determining contaminant removal rates is important for creating wetland design standards for graywater treatment and reuse. Contaminant removal rates were evaluated over the summer and fall of 2010 and 2011 for a SF wetland. These removal rates were compared to the removal rates evaluated over a two year period (2008-2010) for a FWS wetland. Another objective was to determine the % mass removal of three common anionic surfactants in constructed wetlands (both FWS and SF) and finally, the possibility of incorporating constructed wetlands into greenhouse community garden centers as an option to reduce the losses resulting from evapotranspiration (ET) in arid climates was explored briefly. The results indicate that SF wetlands provide relatively stable and more efficient treatment year round when compared to FWS wetlands. In particular, the SF wetland showed statistically significant higher mass removal of both biological oxygen demand (BOD5 ) and total nitrogen (TN) than the FWS wetland during winter months (P=0.1 and 0.005; α=0.1). When all the seasons were compared for each wetland individually there was a statistically significant degree of removal for BOD5 and TN between the seasons in the FWS wetland (P=0.09 and 0.04; α=0.1) while there was none in the SF wetland (P=1.0 and 0.9; α=0.1). These results are consistent with other findings in the literature. When mass removals were compared to HLRs, the trends support the ability of SF wetlands to function across a wide range of HLRs and climatic conditions, whereas FWS wetlands are less capable of performing well under less than ideal conditions. Results of the k-C* and SA analyses, though limited in their completeness, suggest once again that SF wetlands are capable of increased rates of removal not only during the warm summer months but also during the winter and transition months. Specifically, nitrification and denitrification processes may be contributing to TN removal in the SF wetland, particularly during senescent periods. Surfactant removal was also consistent with findings in the literature, with 50% removal of LAS and greater than 70% removal of AES/AS, suggesting that LAS is more persistent.Item Open Access Graywater application for landscape irrigation: greenhouse studies(Colorado State University. Libraries, 2010) Shogbon, Alicia R., author; Sharvelle, Sybil E., advisor; Shackelford, Charles D., committee member; Qian, Yaling, committee memberOver the years, residential graywater application for landscape irrigation has garnered increasing popularity. Concerns however exist regarding the potential negative impacts that graywater pose to plant health and environmental quality. Due to the variability in field conditions such as graywater loading rate, soil type, climate and rainfall amount difficulty exists in accurately determining the potential for groundwater contamination. The need therefore arises to evaluate impacts of graywater irrigation in a controlled environment to develop scientifically justified conclusions regarding the fate of graywater constituents. The objective of this study was to conduct experiments in a greenhouse to evaluate the potential for groundwater contamination by conducting leachate analysis. Plant health was also evaluated throughout the duration of the experiment. The experiment setup involved the use of thirty-eight custom polyvinyl chloride (PVC) pots. These pots were setup in the Colorado State University greenhouse. Potable water served as a control for the experiments. Two different plants and two different turfgrasses were utilized. The turfgrasses were bermudagrass (a warm season grass) and tall fescue (a cool season grass). The landscape plants used were euonymous (a shrub) and lemon (a citrus). The pots were setup to allow for leachate collection from the bottom. The leachate volume was monitored and recorded and leachate analyses were conducted for boron, sodium adsorption ratio (SAR), nitrate, ammonium, total nitrogen (TN), total dissolved solids (TDS), total suspended solids (TSS), volatile suspended solids (VSS), total organic carbon (TOC), sulfate, conductivity and surfactants (linear alkylbenzene sulfonate (LAS), alkyl ethoxy sulfate (AES), and alcohol ethoxylate (AE)). Analysis of the leachate from the graywater irrigated pots revealed on average, elevated levels of TOC, TN, nitrate, ammonium, TDS, TSS, VSS, sulfate, conductivity, boron and SAR when compared to the concentrations measured in the leachate from the control systems. The average concentrations of TOC, TSS, VSS , ammonium, nitrate and TN measured in the leachate from the graywater irrigated plant/grass systems were however lower than the concentrations in the synthetic graywater. An expected increase in conductivity and TDS in the leachate from the graywater irrigated pots was found. Results further indicate the accumulation of boron and salts (indicated by SAR) in the graywater systems with a trend of increasing concentrations with time and a subsequent increase in measured leachate concentrations above the input concentration measured in the graywater. With the exception of boron and salts, there was substantial percentage retention of graywater constituents through the soil column such that there was lower measured concentrations of the graywater constituents in the soil leachate compared to the input concentrations.Item Open Access Graywater reuse guidance and demonstration using a constructed wetland treatment system(Colorado State University. Libraries, 2011) Bergdolt, Jesse Hawk, author; Sharvelle, Sybil E., advisor; Roesner, Larry A., advisor; Glick, Scott, committee memberCommunities throughout the United States and abroad are developing interest in innovative approaches to sustaining their freshwater resources. One method, graywater reuse for non-potable demands, is gaining popularity because it allows the reuse of minimally contaminated wash water generated at the home/office for non-potable demands, which then reduces the demand for treated water and preserves source waters. Graywater is defined as any wastewater generated at the home or office excluding water from the toilets, kitchen sinks, and dishwasher, but includes wastewater from the laundry, shower, and bathroom sinks. When compared to other wastewater generated in the home graywater is minimally contaminated with lower concentrations of organics, solids, nutrients, and pathogens, thereby rendering the water suitable for reuse with minimal treatment when compared to other domestic wastewater sources. Despite widespread interest in this innovative approach information on the separation and design of residential and/or commercial scale graywater systems have been limited. The objective of this study was 1) to provide a graywater reuse manual for home or business owners interested in separating sources of graywater from blackwater for graywater reuse and 2) to determine the first order removal rates (k) of graywater constituents using both a free water surface (FWS) and subsurface flow (SF) constructed wetlands, in order to provide design guidance for future constructed wetlands that will be used to treat graywater. Information regarding the separation and reuse of graywater is important to the success of graywater reuse systems. This thesis provides information to business and home owners about the separation of graywater from blackwater for graywater reuse. Part one of this thesis outlines the methods and equipment needed to install a dual plumbing system for the purpose of graywater reuse. Part one also describes how to design an individual graywater reuse system specific to the needs of the home or business owners, the technologies and equipment necessary for graywater reuse systems, known maintenance requirements for graywater systems, and best management practices to ensure safe reuse of graywater. Individual graywater reuse systems for the home or office are too small to treat large amounts of graywater produced by residential neighborhoods or communities. Consideration should be given to treatment options that can handle and treat a large amount of graywater. Constructed wetlands can offer a scalable, economically sound, low tech and easily maintained method of treating graywater for large scale irrigation reuse. While constructed wetlands are an appropriate technology for graywater treatment there is little research providing the removal rates for the design of constructed wetlands for graywater reuse. Determining removal rates is important for creating wetland design standards for graywater treatment and reuse. Part two of this thesis provides the experimental results for determining the seasonal flow adjusted removal rates (k) of graywater constituents using a free water surface (FWS) constructed wetland and a subsurface flow (SF) constructed wetland. Removal rates were evaluated over a two year period (2008-2010) for a FWS wetland and evaluated over the summer/fall of 2010 for a SF wetland. The results for the FWS included the biochemical oxygen demand (BOD5) removal rates of 15.9 (m yr-1) for summer removal, 15.2(m yr-1) for fall removal, and 5.6 (m yr-1) for winter/spring removal. The total nitrogen (TN) removal rates were 16.4 (m yr-1) for summer removal, 8.5 (m yr-1) for fall removal, and 5.5 (m yr-1) for winter removal. The total organic carbon (TOC) removal rates were 10.4 (m yr-1) for summer removal and inconclusive for the TOC removal in the fall and winter seasons. The results for the SF during the summer included a BOD5 removal rate of 19.1 (m yr-1), a TOC removal of 22.8 (m yr-1), a TN removal rate of 21.3 (m yr-1), and an ammonia removal rate of 32.6 (m yr-1). The results were inconclusive for the fall season due to a limited amount of data. When compared to other literature k values for sizing wetland for agricultural and municipal wastewater, results from this study had lower k values for BOD, which resulted in a larger required surface area (SA) for wetland design. The TN and ammonia k values were comparable to other literature design values.Item Open Access Implications of solid and liquid waste co-disposal on biodegradation and biochemical compatibility(Colorado State University. Libraries, 2018) Cook, Emily M., author; Bareither, Christopher A., advisor; Sharvelle, Sybil E., advisor; Ippolito, James A., committee memberCo-disposal of solid and liquid waste in municipal solid waste (MSW) landfills can benefit landfill operations via enhancing waste moisture content and accelerating in situ waste biodegradation. However, implications of co-disposal on organic waste biodegradation are currently unknown and co-disposal in full-scale landfills is ad hoc. The objective of this study was to evaluate waste biodegradation and biochemical compatibility for different co-disposed solid and liquid wastes in MSW. To meet this objective, laboratory-scale reactors were operated to evaluate the potential impacts of co-disposal and ultimately to provide guidance for full-scale MSW landfill operations. Waste collected for this project was identified as MSW, special solid waste (SW), liquid waste (LW), and sludge waste (Sludge), such that reactor experiments were conducted with representative co-disposal combinations of MSW-SW, MSW-LW, and MSW-Sludge. The MSW-SW and MSW-Sludge reactors included landfill leachate as a liquid source to generate effluent; MSW-LW reactors were operated with unique liquid wastes. The MSW-LW reactors remained in the acid formation phase of biodegradation for the duration of the experiment. The liquid waste addition in the MSW-LW reactors was not an effective means to initiate biodegradation and is not recommended as an additive to fresh MSW without an inoculum that contains methanogenic microorganisms. All MSW-Sludge waste reactors and all but one set of the MSW-SW reactors reached methanogenesis. The solid and sludge wastes did not exhibit signs of biochemical incompatibility. The use of biochemical methane potential (BMP) assays as a selection tool for waste co-disposal was also evaluated. The BMP assays did not show good agreement with data from reactors that generated methane; therefore, use of BMP assays alone as a selection tool is not recommended.Item Open Access Phase-based analysis to determine first order decay rates for a bioreactor landfill(Colorado State University. Libraries, 2017) Nwaokorie, Kelechi J., author; Bareither, Christopher A., advisor; Sharvelle, Sybil E., advisor; von Fischer, Joseph C., committee memberIn recent years, the goal of municipal solid waste (MSW) landfill management has transitioned from waste sequestration to waste stabilization. A bioreactor landfill is an MSW landfill operated with a deliberate goal to achieve waste stabilization via in situ organic waste decomposition. Enhanced landfill gas (LFG) generation that results from moisture addition to increase the rate of anaerobic biodegradation can have different consequences on landfill operations. Additionally, landfills commonly are constructed and filled in phases (i.e., delineated areas of the landfill where waste is placed) that are operated with different moisture enhancement strategies. Thus, there is a need to simulate and predict LFG generation in a bioreactor landfill on a phase-specific basis to more accurately assess waste decomposition and progression of organic waste stabilization. In this study, site-wide and phase-specific LFG modeling was conducted for a bioreactor landfill. A phase-specific LFG modeling approach was developed and used to assess six separate phases of the landfill. This approach included a temporal estimate of waste disposal and separation of LFG collection data for the six phases. Landfill gas collection in each phase was used to compute methane collection based on gas composition analyses and used to estimate methane generation based on two considerations of collection efficiency: constant collection efficiency of 85% and temporally varying collection efficiency. Methane generation was predicted using the U.S. EPA LandGEM. Model simulations were compared with adjusted methane collection data to optimize the first-order decay rate (k), which was the primary variable used to assess waste decomposition and stabilization. First-order decay rates were optimized for site-wide and phase-specific analyses that considered (i) monthly versus annual averaging techniques for LFG data, (ii) collection efficiencies, and (iii) LFG collected only in the gas wells versus LFG collected in gas wells and perforated pipes in leachate collection and recirculation systems. The recommended gas modeling approach is to use monthly average LFG flow rates, a constant collection efficiency of 85%, and LFG collected from gas wells and leachate collection / recirculation systems. The optimized k for the site-wide analysis was 0.078 1/yr, whereas the default k for conventional MSW landfills with no moisture enhancement is 0.04 1/yr. Thus, the site-wide k supports enhanced organic waste biodegradation and stabilization. The optimized ks for the phase-specific analyses ranged between 0.025 and 0.13 1/yr, which suggest that although the overall site was operating at an enhanced rate of waste decomposition, the rate varied between landfill phases. Moisture addition via leachate recirculation and liquid waste addition was implemented at the landfill for the five more recent phases. The k values for these five phases increased with increasing liquid addition per waste mass whereby the optimized k values increased from the driest phase, Phase 3 & 4 (0.037 1/yr), to the wettest phase, Phase 6 (0.127 1/yr). The LFG modeling and findings from this study can assist with developing moisture enhancement strategies for bioreactor landfills and assessing LFG collection data to support claims of enhanced waste decomposition and stabilization.