UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
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Item THE USE OF ORGANIC WASTE PRODUCTS AS SOIL AMENDMENTS FOR TURFGRASS ESTABLISHMENT: EFFECTS AND REGULATORY INFLUENCES(2024) Morash, Jennifer Dawn; Lea-Cox, John; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The use of organic waste products as soil amendments in highly disturbed urban soil is poised to grow due to rising fertilizer costs, waste-management issues, and greater emphasis on creating sustainable circular economies. Despite the advantages of using waste products as organic amendments to enhance fertility, their incorrect use may result in short-term unintended consequences such as nutrient losses or the immobilization of plant-essential nutrients, which could diminish efforts to establish vegetation on disturbed soil. To avoid these consequences, transportation authorities – cited as the largest users of compost in some states – have implemented measures to improve product specifications. This research details the efforts of one such organization, the Maryland Department of Transportation State Highway Administration (MDOT SHA), and the results of an initiative to increase the quality of manufactured topsoil and compost use through agency topsoil specifications. After determining which products were most likely to be incorporated into manufactured topsoil (finely shredded wood mulch and composted leaf yard waste), two greenhouse microcosm experiments were conducted to evaluate plant growth responses and the efficiency of nutrient uptake compared to leachate losses when those amendments were used in accordance with MDOT SHA specifications. Composted yard waste provided excellent results while wood mulch suppressed growth in the short-term studies. A biosolids treatment was included in the experiments due to widespread availability and growing interest. Biosolids improved soil fertility and plant growth. However, the difference between nitrogen (N) uptake and leachate mass losses required a second set of experiments, to quantify the effects of four biosolids amendments on plant growth, nutrient uptake, and leachate losses. Treatments were applied at the rate recommended by UMD for turfgrass establishment (2.54 cm, incorporated) and included fresh biosolids, biosolids that were stockpiled for two years, two blended products made from either the fresh or aged biosolids and fine wood mulch, an inorganic fertilizer, and a control. Aging and wood fines reduced N leaching losses but at the expense of N inputs to soil. The cumulative N leachate mass loss from the new biosolids treatment was 63 times greater than the cumulative fertilizer total. Aging did not reduce phosphorus (P) leaching losses but wood fines did by diluting the concentration of P in blends. However, biosolids mostly retained P in the soil and cumulative fertilizer losses were 2 times higher. Overall, growth measurements showed that biosolids enhanced growth during the first and second growing seasons. However, based on the results of this research, 2.54 cm of pure biosolids is not required to enhance turfgrass establishment. An application of 1.27 cm of pure biosolids or 2.54 cm of a biosolid/wood fine blend should provide comparable enhanced turfgrass growth results while reducing overall nutrient leachate losses.Item Biosolids and Compost For Urban Soil Restoration and Forestry(2022) Keener, Emily Cathryn; Pavao-Zuckerman, Mitchell A; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Elements of urban soil quality such as compaction and low organic matter are underexamined, important challenges to urban afforestation. In this Beltsville, Maryland field experiment, I examined biosolids and compost as amendments to improve soil quality and planted tree survival in a degraded urban proxy soil and identified correlations between soil properties and tree survival. Organic amendments increased organic matter content, decreased bulk density, and had no effect on tree survivorship compared to controls. Effects on soil were more profound and lasting with compost than with biosolids. Soil organic matter and bulk density were correlated with tree survival early in the study and microbial respiration was correlated with tree survival throughout the study. High tree mortality was driven by transplant shock, limiting insights from tree response data. This study highlights the importance of soil quality and good planting practices in future research.Item EFFECTS OF FULL-SCALE THERMAL HYDROLYSIS-ANAEROBIC DIGESTION ON THE TEMPORAL TRENDS OF POLYBROMINATED DIPHENYL ETHERS IN BIOSOLIDS AND THEIR PHYSICAL AND BIOLOGICAL DEGRADATION DURING WASTEWATER TREATMENT(2020) Motley, Taylor Ann; Torrents, Alba; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Biosolids produced at wastewater treatment plants (WWTPs) are rich in recovered nutrients and are often recycled through soil amendment on agricultural land. Advanced solids treatment strategies, including thermal hydrolysis pretreatment (THP) and anaerobic digestion (AnD), are utilized to produce cleaner, safer biosolids based on EPA classifications. Despite the phase-out of the flame retardant polybrominated diphenyl ethers (PBDEs) from commercial use in the U.S., they are still present in biosolids and can be degraded to toxic byproducts during solids treatment. Their transformation during solids treatment is not well understood. This work shows that while phase-outs of PBDEs did not affect their concentrations in biosolids from the target WWTP, the implementation of THP-AnD treatment in 2014 led to increased PBDE degradation during solids treatment. This significantly lowered PBDE concentrations and shifted congener distribution to favor smaller, more toxic congeners in final biosolids compared to lime-stabilized biosolids historically produced at the target WWTP. Comparisons between the target WWTP and other AnD facilities without THP revealed that more efficient PBDE degradation occurred during THP-AnD treatment despite lower abundances of debrominating bacteria in digesters. Future work will examine if PBDE degradation during THP-AnD treatment is due to physical or biological processes.Item High Quality Biosolids: Assessment of Nitrogen Mineralization and Potential for Improving Highway Soils(2019) Zhu, Chenglin; Felton, Gary K; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Biosolids production is increasing with increase in human population. Over the years, the quality of biosolids has been improving with the upgrading of most wastewater treatment plants (WWTP) as dictated by a need to meet discharge limits in receiving water bodies. Applying biosolids to agricultural soils to improve crop production has been practiced for decades. With increased regulation on land application in agricultural lands, biosolids industry has been exploring ways to use biosolids in specific situations such as highway roadside soils to improve soil properties. Roadside soils are known to be compacted and contaminated due to vehicular traffic and typically have low organic matter and nutrients. The objective of this study was to investigate the efficacy of high quality biosolids (i.e. Bloom) to improve soil physical and chemical properties. Results showed that Bloom and its mixture can significantly improve soil bulk density and hydraulic conductivity. Bloom-amended soils had a higher nitrogen mineralization rate than the control (2.45 times faster in simulated roadside soil and 1.21 times faster in agricultural soil) and compost amended soil. Further, soils amended with cured Bloom had relatively slower N mineralization than those applied with uncured Bloom since the curing process will decrease organic matter (OM) content and facilitate the loss of N as ammonium. The take home message is that bloom is more effective than inorganic fertilizer in terms of improving soil physical properties for roadside soils and bloom mixed with sand and sawdust is more effective than pure bloom. Bloom addition can significantly increase soil organic nitrogen mineralization. Further study and analysis will be needed to conclude on the effect of deer compost on soil physical properties and the mineralization rate of Orgro amended soil.Item BLOOM BIOSOLIDS: WHAT IS THEIR MICROBIAL COMMUNITY AND HOW DO THEY AFFECT SOIL AND PLANT HEALTH?(2019) Baballari, Eni; Yarwood, Stephanie; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Biosolids are rich in nutrients and organic matter, and are known to improve and maintain productive soils and stimulate plant growth. D.C. Water’s new Class A biosolids product, Bloom, was evaluated for its impact on plant and soil health. Using molecular tools, Bloom was examined for the presence of functional genes that would indicate the presence of microbes capable of improving plant growth (i.e.nitrifiers, N- fixers). Using greenhouse and laboratory experiments, we determined Bloom’s effect on plant growth, carbon and nitrogen cycling. Bloom has both nitrifying and N-fixing microbes, but their gene numbers vary depending on the stage of production. We show that plants, such as cucumber and tomato, grown in soil amended with Bloom produce more leaves and stems and have higher aboveground biomass, and soybeans produced more bean pods. Lastly, we found that N-mineralization is higher in soil amended with Bloom, even after one growing season, providing increased nutrients.Item CHARACTERIZATION OF LEACHABLE DISSOLVED ORGANIC MATTER FROM BIOSOLIDS AND IMPLICATIONS FOR NUTRIENT RELEASES, MODELING, AND EMERGING CONTAMINANTS(2019) Fischer, Sarah Jane; Torrents, Alba; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Treated wastewater residuals are utilized as a soil amendment to recycle nutrients to agricultural soils. Due to international application, biosolids are also a significant source of anthropogenic dissolved organic matter (DOM) to the environment. The first contribution of this dissertation characterized DOM and nitrogen mineralization rates of anaerobically digested (AnD) biosolids with variable pre-treatments, such as the thermal hydrolysis pretreatment coupled to anaerobic digestion (THP-AnD). There was not strong evidence that differently pretreated-AnD material had largely different aerobic inorganic nitrogen releases when incubated in a sandy loam soil. Variable pools of DOM decayed in soil treatments over time. Biosolids-DOM was then characterized from a greater representation of full-scale stabilization processes including (i) limed stabilization (LT), (ii) aerobic digestion (AeD), and (iii) anaerobic digestion (AnD). These different final stabilization processes produced substantially different leachates characterized by organic carbon content, size-exclusion chromatography, and fluorescence spectroscopy. Traditional optical metrics previously defined for aquatic DOM did not consistently capture fluorescence maxima of the anthropogenic material. Therefore, boundary-based excitation emission matrix (EEM) analyses were re-defined based on local fluorescence maxima. Novel parallel factor analysis (PARAFAC) and spectral database comparisons confirmed that biosolids-DOM contain both common high energy stimulated components and low energy stimulated components that are unique to digested leachates. The third research contribution applied fluorescence suppression experiments to measure interactions of halogenated ECs with contrasting biosolids-DOM types. Despite digested biosolids-DOM containing different humic acid-like or fulvic acid-like signatures than limed leachates, antimicrobial triclocarban and industrial compound 2-4 dichlorophenol suppressed similar high energy fluorescent signatures in all biosolids-DOM. This suggests TCC and 2-4 DCP electronically interacts with smaller aromatic compounds, such as amino acids, and this interaction is not unique to DOM from different waste stabilizations. This study contributes to future bioavailability assays modeling complex effects of leachate quality on halogenated contaminants. This thesis also confirmed the presence of dehalogenating microbes in the anaerobic microbial community structure of a THP-AD system. These results contribute to on-going work assessing solids treatments, where halogenated emerging contaminants can be dehalogenated before land application. This work advances understanding of biosolids DOM leachates, modeling EEM data, and fate of ECs during full-scale solids treatment processes.Item ENHANCED PRODUCTION OF BIOSOLIDS BY IMPROVED ACTIVATED SLUDGE CLARIFICATION AND STRUCTURED WATER ANALYSIS(2017) Liu, Xiaocen; Kjellerup, Birthe Veno; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Biosolids contain high contents of soil-required nutrients, so that have been widely applied in land application. The production of the biosolids depends on the clarification performance and dewaterability of the sludge, which are influenced by bioflocculation and structured water content, respectively. Therefore, research on sludge bioflocculation improvement and structured water content determination were proposed in this study. The result indicated that different activated sludge exhibited various bioflocculation limitations. Influence of the sludge characteristics such as the extracellular polymeric substances (EPS) composition, viscosity and floc size on the structured water content were also investigated. The results indicated that no significant correlation was observed between the EPS composition and the structured water content, however, the sludge floc size was positively correlated with it. The bioflocculation limitations were pinpointed, and how floc size influenced the structured water content needed further studies to improve sludge dewaterability, therefore, enhance the biosolids production quantitatively and qualitatively.Item FULL SCALE STUDY OF PATHOGEN, METAL POLLUTANTS, NUTRIENTS, AND POLYBROMINATED DIPHENYL ETHERS IN CLASS A BIOSOLIDS STABILIZED BY THERMAL HYDROLYSIS AND ANAEROBIC DIGESTION PROCESSES(2017) Wang, Xuanzhao; Torrents, Alba; Andrade, Natasha Almeida; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Class A biosolids are solid by-product of wastewater treatment which meet Environmental Protection Agency requirements to be used as fertilizer in farms, vegetable gardens, and can be sold directly to consumers. In 2014, this study’s target nutrient recovery facility adopted thermal hydrolysis pretreatment and anaerobic digestion to upgrade biosolids quality from Class B (previously lime-stabilized) to Class A. In order to certify if this newly produced material met all regulatory requirements, we performed laboratory analysis to characterize fecal coliforms, volatile solids, and metals content. In addition, we showed a baseline for nutrient management of total nitrogen, phosphorus, and the change in levels of polybrominated diphenyl ethers (PBDEs). Samples were collected for over a year since the start of THP-AD operation. Results were compared with the Class B biosolids produced at the same facility. Based on EPA standards, Class A biosolids were produced with stable quality after March, 2015, 16 weeks after process initiation. This work suggests that THP-AD is effective in producing Class A biosolids. In general, PBDEs in biosolids decreased from 1790 ± 528 (Class B) to 720 ± 110 µg/kg d.w. Our results suggest that the total levels of PBDEs decrease, however, the impact of the THP-AD on specific congeners are complex.Item FATE AND TRANSPORT OF NITROGEN AT A DEEP ROW BIOSOLIDS APPLICATION HYBRID POPLAR TREE FARM(2012) Maimone, Diana; Felton, Gary K; Biological Resources Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study evaluates deep row applied biosolids as a nutrient source for hybrid poplar trees grown on a gravel mine reclamation site in Brandywine, Maryland from November 2003 to April 2009. The study included biosolids application rates of 386, 773, and 1,159 dry Mg/ha (172, 345, and 517 dry ton/ac.) and hybrid poplar tree densities of 0, 716, and 1,074 trees/ha (0, 290, and 435 trees/ac.). Soil water samples taken from suction lysimeters located 15 - 120 cm (6 - 48 in.) vertically below the biosolids were analyzed for total ammoniacal-nitrogen (TAN) and nitrate-nitrogen (NO3-N). The majority (96.3%) of NO3-N values were less than EPA drinking water MCL of 10 mg/L. No NO3-N values within the tree plots exceeded 2 mg/L. The TAN concentrations increased with application rates, but decreased with distance from the biosolids, except there was no difference between 60 cm (24 in.) and 120 cm (48 in.).Item Steriod Hormones in Biosolids and Poultry Litter: A Comparison of Potential Environmental Inputs(2010) Bevacqua, Christine Elizabeth; Torrents, Alba; Rice, Clifford; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Steroid hormones can act as potent endocrine disruptors when released into the environment. The main sources of these chemicals are thought to be wastewater treatment plant discharges and waste from animal feeding operations. While these compounds have frequently been found in wastewater effluents, few studies have investigated biosolids or manure, which are routinely land applied, as potential sources. This study assessed the relative environmental contribution of steroid hormones from biosolids and chicken litter. Samples of limed biosolids collected over a four year period and chicken litter from 12 mid-Atlantic farms were analyzed for 17β-estradiol (E2), estrone (E1), estriol (E3), 17α-ethinylestradiol (EE2), progesterone, and testosterone, and the conjugated hormones E1-sulfate (E1-S), E2-3-sulfate (E2-3-S), and E2-17-sulfate (E2-17-3). Results showed that E1 and progesterone were the most prevalent compounds in both of these materials, with E1-S also present in chicken litter.