Theses and Dissertations from UMD
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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 give thesis/dissertation in DRUM
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Item Innovative Reuse of Baltimore Harbor Dredged Material as Vegetative Earthen Berms(2024) Smith, Adam; Davis, Allen P; Aydilek, Ahmet H; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Dredged material (DM) is a sediment excavated from navigable waterways, which haslimited use due to the transport and accumulation of potentially hazardous metals and organic chemicals into these waterways. DM can be used as a recycled material in place of soil, depending on its environmental and physical characteristics, and the specific use. Vegetated Earthen Berms (VEBs), used for stormwater control, is one potential beneficial application of DM. The objective of this research is to assess the environmental and geotechnical suitability of DM in VEBs. A germination study and a battery of column tests were conducted to test the innate properties of the DM and DM amended with straw and sand, as DM blends. Straw and sand were chosen to observe potential improvements to the DM’s physical and chemical parameters. A nine-week mesocosm study was performed to simulate the overall performance of DM and DM blend constructed VEBs for the plant growth and water quality criteria, determined by US EPA water quality limits. Plant cover and growth measurements along with measuring effluent water characteristics were assessed. Straw amended DM was shown to have comparable vegetative establishment parameters relative to topsoil. For the water quality, concentrations of dissolved copper and zinc were reduced relative to typical median stormwater values in DM constructed VEBs. Based on the results of these tests, DM constructed VEBs had reflected desirable qualities for potential reuse based on water quality and vegetative establishment.Item PREVENTION AND TREATMENT OF PERSISTENT ORGANIC POLLUTANTS IN STORMWATER AND SEDIMENT(2023) Yuan, Chen; Kjellerup, Birthe V; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Polycyclic aromatic hydrocarbons (PAHs) and Polychlorinated biphenyls (PCBs) are two groups of persistent organic pollutants (POPs) with toxicity, carcinogenicity, and teratogenicity. Those compounds are harmful to human health and wildlife. Stormwater is one of the important sources of PAHs and PCBs to aquatic environments. Stormwater control measures (SCMs) have already been used to remove PAHs and PCBs from stormwater, however traditional SCMs can remove PAHs and PCBs in the particle phase, but there still are dissolved PAHs and PCBs in the outflow of SCMs. This study focused on reducing the influence of PAHs and PCBs in stormwater on the environment by 1) improve the treatment performance by adding a polishing treatment procedure after traditional SCMs, and remove the PAHs and PCBs accumulated in the polishing treatment media by bioaugmentation of Pseudomonas putida ATCC 17484 and Paraburkholderia xenovorans LB400 and 2) dechlorination of PCBs in the sediment of aquatic environments by biofilm Dehalobium chlorocoercia DF1 inoculum. The results of polishing treatment showed that all black carbon materials, namely biochar, granular activated carbon (GAC), and regenerated GAC (RAC), were effective to remove dissolved PAHs with removal > 95%. However, all materials had lower removal efficiency on PCBs with removal > 84%, By the comparation of cost and lifetime under the condition that 50% polishing media are used in the polishing treatment facility. RAC which has a lifetime>147 years based on the precipitation of Maryland and Washington and cost <3.79 $-m3-yr-1, was the best material for polishing treatment. Results of treatment train with a traditional SCM media column and polishing treatment column indicated that average removal of PAHs can be improved from 94.56% of BSM columns to 99.61% of polishing treatment columns, and removal of PCBs can be improved from 84.61% to 95.16%. Results of bioaugmentation of polishing treatment media showed no biodegradation took place in the mesocosms with polishing media. However, the liquid mesocosms showed P.putida degraded 97.9% of pyrene. The bacteria colony on plates after the biodegradation experiment showed that there were less P.putida and P.xenovorans colony of polishing media mesocosms than liquid mesocosms. Therefore, the limitation of biodegradation of polishing media mesocosms may cause by the limited bioavailability and less active inoculated bacteria. The results of dechlorination by Dehalobium chlorocoercia DF1 biofilm shows that there were native bacteria, such as Gemmatimonadetes, Actinobacteria, Proteobacteria and Firmicutes in the sediment that can dechlorinate PCBs. The three treated mesocosm groups (addition of biochar, bioaugmentation with DF1 biofilm and liquid DF1 culture) all can improve dechlorination, of 28.09%, 21.30%, and 17.10%, respectively. Those three groups had dechlorination extent higher than negative control (4.60%), and abiotic control (-1.02%). The microbial community analysis indicated that biofilm inoculation improved abundance of DF1 and had a more stable influence on the community than liquid inoculation. Overall, biofilm inoculation and addition of biochar dechlorinate PCBs in sediment efficiently, and polishing treatment is an efficient approach to improve traditional SCMs, while treating the polishing media with bioaugmentation need further study.Item Polycyclic Aromatic Hydrocarbons (PAHs) and PAH Degrading Bacteria in Media of a Stormwater Bioretention Cell(2020) Yuan, Chen; Kjellerup, Birthe; Davis, Allen; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Polycyclic aromatic hydrocarbons (PAHs) are a group of organic pollutions that are carcinogenic to humans. A bioretention cell at the campus of University of Maryland, College Park, evaluated for their potential to remove PAHs from stormwater. The risk of PAH pollution was confirmed by the fact that the highest value of total PAH concentration (25.5 μg/g) and the average concentrations of pyrene (1.78 μg/g) and chrysene (1.40 μg/g) was higher than their respective probable effect concentrations (PECs) (22.8 μg/g, 1.52 μg/g and 1.29 μg/g),. Sources of PAHs in the media originated from fossil fuel combustion and petroleum. Human carcinogenicity was evaluated by determining the Benzo[a]pyrene Total Toxicity Equivalent (BaP-TEQ), and benzo[a]pyrene made most contribution to carcinogenicity. Biotransformation of PAH is possible in bioretention cell, because PAH-ring cleaving dioxygenases (PAH-RCD) gene was found in media.Item Evaluating Gutter Filter Performance After 10 Years Operation(2019) Greenfield, Madeleine; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Urban stormwater runoff contains various pollutants that degrade downstream water quality. Gutter filters, below-grade filtration devices that capture sheet flow, are an ideal stormwater control measure for urban retrofits because of their small footprint. A 10-year-old gutter filter system in Mt. Rainier, MD was monitored for 18 storm events over 13 months for total suspended solids, nitrogen, phosphorus, and copper, zinc, and lead in the downstream stormwater. The filters had received no maintenance since their construction. The stormwater quality was compared to studies conducted prior to installation and immediately after installation of the filters. Total Kjeldahl Nitrogen concentrations displayed a statistically significant increase since installation. All other pollutants did not show a significant change over the 10 years. Nonetheless, overall runoff water quality was not good. Event mean concentrations are comparable to highway runoff and annual pollutant loadings are comparable to untreated runoff from other urban drainage areas in the region.Item REMOVAL OF STORMWATER DISSOLVED ORGANIC NITROGEN MODEL COMPOUNDS THROUGH ADSORPTION AND BIOTRANSFORMATION(2019) Mohtadi, Mehrdad; Davis, Allen P.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bioretention systems are stormwater control measures designed to reduce nitrogen and phosphorus transferred by stormwater to water resources. They are, however, not effectively designed to remove dissolved organic nitrogen (DON). This study concentrated on improvement of bioretention design to remove stormwater DON. Batch adsorption of eight organic nitrogenous compounds onto several adsorbents showed that coal activated carbon (AC) could be a reliable adsorbent for removal of organic nitrogenous compounds such as pyrrole and N-acetyl-D-glucosamine (NAG). The adsorption capacity of pyrrole and NAG on coal AC were 0.4 mg N/g (at equilibrium concentration, Ce = 0.02 mg N/L) and 0.71 mg N/g (at Ce = 1 mg N/L), respectively. These eight nitrogenous compounds were also tested for continuous column adsorption on a media mixture of coal AC + quartz sand, and only pyrrole showed an appreciable adsorption performance; the breakthrough and exhaustion depths for pyrrole were 88 and 499 m, respectively, at the fixed superficial velocity of 61 cm/h and influent DON concentration of 1 mg N/L. Pyrrole adsorption was also minimally affected by superficial velocity (DON removal efficiency stayed > 91% for all tested superficial velocities, 7 to 489 cm/h). Because the adsorption process was successful for removal of only one (pyrrole) out of eight examined compounds, biological treatment was also investigated for removal of organic nitrogenous compounds. Biotransformation alongside adsorption demonstrated benefits such as ammonification of bio-recalcitrant organic nitrogen compounds, e.g., pyrrole, and bioregeneration of the adsorbent (coal AC). According to the results, ammonifiction might be considered as a possible reliable mechanism for stormwater DON removal at low temperatures > 4°C. Under intermittent wetting/draining conditions, the effluent DON was less than 0.1 mg N/L after the applied depth of 48 m, indicating that DON was successfully removed through simultaneous adsorption/ammonification, although generated ammonium in the effluent must be properly addressed. Overall, based on the results from the current study, some DON types were strongly adsorbed by adsorbents, e.g., adsorption of pyrrole on coal AC, some were more bioavailable, e.g., ammonification of leucine, and some were barely adsorbable and bioavailable, e.g., Aldrich humic acid on coal AC. Accordingly, both adsorption and biotransformation should be considered to enhance stormwater DON removal as much as possible.Item REGENERATIVE STORMWATER CONVEYANCE: TECHNIQUES TO WATERSHED STEWARDSHIP & TURNING STORMWATER LIABILITIES INTO AMENITIES(2018) Zerfas, Matthew; Kweon, Byoung-Suk; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Regenerative Stormwater Conveyance (RSC) is a moderately new best management practice primarily implemented in the mid-Atlantic region. This thesis documents the proposed design of an RSC at Parkdale High School in the Washington D.C. metropolitan region. A degraded channel with incised banks between 9 to 12 feet in height was found on site. This stormwater channel runs for 160 feet and has a contributing catchment of 17.2 acres. The proposed RSC was designed to stabilize the channel banks, and create a stable channel profile. The runoff storage volume was calculated to be 4523.1 ft3 total which would treat a runoff volume of 0.24”. This equates to 32% TN, 37% TP and 40% TSS removal. The design provides a viewing area with a photo point and bank pin that would provide an opportunity for students and teachers to assist in visually documenting sediment deposition and geomorphological changes that may occur.Item Evaluation of Nutrients and Suspended Solids Removal by Stormwater Control Measures Using High Flow Media(2017) Landsman, Matthew Robert; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)High Flow Media (HFM) is able to treat large runoff volumes using small- footprint systems. Seven full-scale HFM Stormwater Control Measures (SCMs) in a residential area were monitored over 11 months to assess the removal of Total Suspended Solids (TSS), Nitrogen, and Phosphorus in First Flush (FF) stormwater runoff. Excellent removal of TSS and particulate-bound nutrients was noted, but, in most SCMs, removal of dissolved species was limited. Sorption of dissolved P occurred, although most likely on captured and suspended sediment and not on the HFM itself. Mineralization and nitrification of dissolved N species during dry periods led to nitrate export. HFM grain size and organic content did not significantly impact TSS or P removal, but higher organic content was associated with higher N removal. FF was present in TSS (strongest), TN, and TP (weakest). Optimal HFM SCM design incorporates sedimentation before filtration.Item Bioretention Media for Enhanced Permeability and Phosphorus Sorption from Synthetic Urban Stormwater(2017) Yan, Qi; Davis, Allen Porter; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bioretention systems have been proven as effective urban stormwater control measures (SCMs), and are commonly used to improve both quantity and quality (pollutant removal) aspects of urban runoff. A promising media modification process is developed to simultaneously achieve both high infiltration rate and improved P removal in bioretention systems, Bioretention soil media (BSM) and a sandy ‘high flow medium’ (HFM) were modified with three Al-based amendments: water treatment residual (WTR), alum, and partially hydrolyzed aluminum (PHA), 10% by dry mass, respectively. The sorption of adenosine monophosphate (AMP) and myo-Inositol hexakisphosphate (IHP), two forms of organic phosphorus, and inorganic phosphate by modified media mixtures were studied. Compared with unmodified BSM and HFM, the sorption of AMP was increased by a factor of 26 and 80 for media with alum and PHA, respectively. Similarly, the IHP removal capacity were increased by factors of 7 and 8, respectively. Alum and PHA modified media mixtures can reduce P concentrations to <0.01 mg P/L within a contact time < 1 min. Adsorption and chemical precipitation are two predominated mechanisms for P removal using modified media mixtures. HFM modified with HFM and WTR showed high permeability and excellent P removal relative to other media mixtures and most importantly, it requires simplified modification conditions and is recommended for use in bioretention and related SCMs.Item Management of Ammoniacal Nitrogen in Stormwater Runoff(2016) Khorsha, Golnaz; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Nitrogen in stormwater runoff plays a dominant role in the eutrophication of receiving waters. The challenge in treating nitrogen lies in its diverse speciation and biological cycling. This work aimed to improve removal of influent and mineralized ammonium through the use of sorption media and nitrification in preparation for subsequent denitrification. Two media, clinoptilolite (ZT) and hydrous-aluminosilicate (CA), were characterized in a series of batch and sorption column experiments, which indicated superior performance of ZT because of its higher capacity (206 months life-expectancy) and faster kinetics (60 min). Competition with Ca2+ and K+ resulted in smaller and slower sorption for both media. Removed ammonium in ZT was highly extractable, signifying its potential bioavailability. Sorption columns exhibited high removal during influent NH4+ increases, desorption with influent concentration drops, and lower ammonium removal upon rewetting/saturateting. Nitrification in bio-active sorptive media enhanced removal efficiency, particularly for alternating wet/saturated-dry/unsaturated conditions, with smaller desorption occurring. ZT application in filtration-based stormwater control measures is recommended.Item MAXIMIZING LANDSCAPE PERFORMANCE AT ADVENTIST HOSPITAL: HEALING THE PEOPLE, HEALING SLIGO CREEK(2016) Sorvalis, George; Ellis, Christopher D; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This paper answers the question of whether a design intervention on Washington Adventist Hospital’s Takoma Park campus can combine stormwater Best Management Practices with outdoor healing spaces, to improve the health of the local creek (Sligo Creek) while creating a restorative environment for the hospital community. To improve the health of Sligo Creek, a campus-wide stormwater analysis was undertaken, in addition to an intervention-site-specific stormwater analysis, and a literature review of stormwater best management practices. To create a restorative environment, a literature review of healing gardens was undertaken, in addition to a campus-wide site analysis, to uncover the most ideally suited site to create a restorative environment.