Theses and Dissertations from UMD
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Item DESIGN MODIFICATIONS TO MINIMIZE POLLUTANT LEACHING FROM COMPOST-AMENDED BIORETENTION(2024) Lei, Lei; Davis, Allen P.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bioretention is an effective stormwater control measure (SCM) recognized for its ability to capture and treat urban runoff within a shallow basin using engineered soils and vegetation. Bioretention studies at laboratory and field scales have shown good to excellent removal efficiency for heavy metals (> 80% to > 90%) and have observed high variablility ranging from negative (net export) to 99% in phosphorus and nitrogen removals. Water quality studies have shown that media selection for bioretention is critical in determining pollutant removal.Incorporating compost into bioretention media is an eco-friendly strategy that not only diverts organic waste from landfills but also provides several benefits improving the performance of bioretention system. This approach enriches the media with organic matter and nutrients for vegetation, boosts water holding and cation exchange capacity, stabilizes the soil structure, and improves the retention of pollutants. However, careful management is essential to mitigate the potential releasing pollutants, including dissolved organic matter (DOM), soluble nutrients, and metals readily associated with DOM, particularly if the compost is derived from biosolids... To maximize the benefits of compost in bioretention, special design modifications aimed at enhancing pollutant removal should be implemented. The objective of this research was to investigate ways to optimize the use of compost in bioretention while minimizing pollutant leaching, Design modifications investigated include layering compost over media, aluminum-based drinking water treatment residual (Al-WTR) addition, and incorporation of an internal water storage (IWS) layer. Treatment performances were evaluated through extractions, batch adsorption studies, large column mesocosms, and column media characterizations. Al-WTR amendment improved sorption of phosphorus, copper and zinc, with capacities increasing from 22.5 mg/kg to 161 mg/kg and 193 mg/kg for P, from 121 mg/kg to 166 mg/kg and then to 186 mg/kg for Cu, and from 121 mg/kg to 166 mg/kg and 186 mg/kg for Zn with 0%, 2% and 4% Al-WTR additions. The multilayered system containing a compost incorporated top layer and an Al-WTR amended bottom layer showed good removal of phosphorus (94% and 96%), copper (88% and 86%) and zinc (92% and 96%), and enhanced nitrogen retention (74.1%) from the stormwater load compared to a mixed system (32.8%) as reported by Owen et al. (2023). The installation of an IWS layer did not show statistically significant influences on phosphorus (91% to 93%, p > 0.05), copper (66% to 90%, p > 0.05) or zinc (94% to 95%, p > 0.05) removals, had limited effect on nitrogen retention from stormwater load during storm events (-117% to -188%, p > 0.05), but promoted denitrification during dry periods. With the IWS layer installed, high levels of iron leaching (130 to 11800 µg/L) were detected, likely due to change in the redox potential (from aerobic to anaerobic). With the objective of removing phosphorus and heavy metals from the stormwater, 5.3% of compost (by dry mass) can be used when layering compost over the Al-WTR amended bioretention media. When the design goal is to remove nitrogen, a fraction of compost up to 2.6%, by dry mass can be used, with layering the compost over the bioretention media and an IWS installed at the bottom.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 NUTRIENT MOVEMENT IN A VEGETATED COMPOST BLANKET AMENDING A VEGETATED FILTER STRIP ON A HIGHWAY SLOPE(2022) Forgione, Erica Rose; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Excess stormwater runoff caused by rapid urbanization and exacerbated by climate change generates many challenges for public safety and the environment. Large runoff volumes contribute to flooding and pollutants in stormwater runoff pose risks to human and environmental health, including toxicity to the aquatic environment caused by heavy metals and nutrient pollution leading to eutrophication, the cause of harmful algal blooms. An effort is being made to improve the efficiency of existing highway stormwater control systems which have limited performance in terms of volume reduction and pollutant removal. To address this issue, amendment of highway Vegetated Filter Strips (VFS) with a Vegetated Compost Blanket (VCB), a layer of seeded compost placed on an established slope, has been proposed. Compost has high water holding capacity and organic matter content which can immobilize contaminants of concern. However, the high nutrient content of compost poses a threat to net beneficial performance since excess nutrient leaching occurs after application. This research has posed the question: Can a VCB be used as a stormwater control measure (SCM) while avoiding excessive nutrient leaching?The VCB/VFS system was assessed through lab-scale, greenhouse-scale, and field-scale experiments. Hydrologic performance was evaluated in field and greenhouse experiments through evaluation of dynamic flow modification, event volume storage, and cumulative volume retention. Water quality performance was assessed through analysis of Total Suspended Solids (TSS), Nitrate + Nitrite (NOx), Total Kjeldahl Nitrogen (TKN), Total Nitrogen (TN), Total Phosphorus (TP), filtered and total Copper, and total Zinc concentrations. Nitrogen (N) and phosphorus (P) in compost are naturally transformed from organic to inorganic, soluble forms through the microbially-mediated process of mineralization. Nutrient removal occurs through adsorption as compost leachate passes through the VFS soil layer. To further investigate nutrient movement, small scale laboratory experiments were completed to determine the N and P compost mineralization rates and theoretical soil adsorption capacities. Nutrient data from greenhouse and field experiments were empirically evaluated using the lab-obtained mineralization data. Nutrient release was simulated and compared to experimental field data using a new open-source software, OpenHydroQual, which combines hydraulic and water quality modeling. VCBs were found to have a significant impact on both flow and volume reduction, though at the highest flowrates, VCBs were unable to significantly reduce flow and instead acted as conveyance. A useful design estimate for representative storage capacity using the saturated moisture content and wilting point of both the VCB and VFS was determined. Significant TSS removal was observed in both the field and greenhouse studies and particulate metals were largely removed; however dissolved copper leaching was observed in the field experiment, as has been observed previously for some compost in stormwater systems. Highly elevated concentrations of nutrients (as high as 100 mg/L TN and 12 mg/L TP) were observed in the effluent of both field and greenhouse experiments, resulting in net nutrient leaching and concentrations above recommended EPA freshwater limits even after 1-2 years. Additionally, mass loading rates at the field site (as high as 41 kg/ac/yr for TN and 14 kg/ac/yr for TP) were 1-2 magnitudes higher than observed influent mass loading rates (~3.8 kg/ha/yr for TN and ~0.47 kg/ha/yr for TP). Through laboratory mineralization studies, N and P mineralization rates were found to differ between compost batches, with initial nutrient content and age/leaching of compost being important factors. Adsorption experiments indicated increasing P adsorption from compost leachate with increasing soil Al+Fe content. Comparisons to greenhouse and field data showed differences in N speciation, likely due to differences in moisture content and temperature causing differing amounts of nitrification and volatilization. OpenHydroQual modeling showed modest results, with varying levels of accuracy for storm hydrograph simulation and mass release. VCBs are not currently recommended for use due to the risk of nutrient and metals pollution, especially in nutrient and metals sensitive watersheds. However, several impactful factors were identified that may reduce nutrient leaching, including compost composition, compost age/leaching, and VFS soil type.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 LOW IMPACT DEVELOPMENT MIXTURE EVALUATION FOR HEAVY METAL REMOVAL(2019) Liang, Liang; Davis, Allen P.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)To address non-point heavy metal pollutant sources to urban stormwater runoff, the LIDMATTM (Low Impact Development MAT) is a stormwater management runoff system designed and manufactured for effective treatment for heavy metals. The LIDMATTM contains approximately 70% sand, 25% manure compost, and 5% steel slag by mass. The LIDMATTM was evaluated based on flow rate, pH, heavy metal removal, and the concentrations of N and P leached; conditions for optimum removal have been quantified. For treating synthetic stormwater runoff, 12 trials were completed using bench-scale and column media testing systems. Average effluent event mean concentrations of all trials were 25 ± 10 μg/L Cu, 21 ± 13 μg/L Pb, and 57 ± 42 μg/L Zn from studies at influent concentrations of 500 μg/L, 300 μg/L, and 100 μg/L, which satisfy Numeric Action Levels (NALs) of Cu, Pb, and Zn by the state of California, USA, Industrial General Permit (IGP). The leaching of nitrogen and phosphorous were also below the NALs.Item Nutrient Leaching from Leaf-and-Grass Compost Addition to Stormwater Submerged Gravel Wetlands(2016) Mangum, Kyle Robert; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Submerged Gravel Wetlands (SGWs) are subsurface-flow wetlands, and are effective stormwater control measures (SCM). Compost addition has many properties beneficial to SGWs but may also lead to leaching of nitrogen (N) and phosphorus (P). To investigate nutrient leaching effects of leaf-and-grass compost addition in SGWs, mesocosm studies were conducted using bioretention soil media (BSM) mixed with 30% and 15% compost, by volume. Synthetic stormwater was applied to mesocosms and effluent analyzed for N and P. Compost-added mesocosms were found to leach N and P. Maximum N concentrations of 16 and 6.4 mg-N/L were reached after 1.7 and 3.0 cm of rainfall for 15% and 30%, respectively. Maximum P concentrations of 2.9 and 0.52 mg-P/L were both reached after 2.5 cm for 30% and 15%, respectively. Particulate P was the dominant P species found in effluent samples, while N species were mixed. Although compost addition led to leaching of N and P, treatment of both nutrients was achieved, with the 15%, reaching a net-zero export of P after the equivalent of 20 cm of rainfall. Nitrogen treatment was attributed to denitrification and plant and microbial uptake. Phosphorus treatment was attributed primarily to adsorption.Item EFFECT OF COMPOST ON THE MICROCLOVER ESTABLISHMENT AND USE OF COMPOST AND MICROCLOVER TO REDUCE LAWN NUTRIENT RUNOFF(2016) Xiao, Xiayun; Carroll, Mark; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)High volume compost incorporation can reduce runoff from compacted soils but its use also associated with elevated N and P concentrations in runoff making it difficult to assess if this practice will reduce nutrient loading of surface waters. Additionally, little is known about how this practice will effect leguminous species establishment in lawns as means to reduce long term fertilizer use. When 5 cm of compost was incorporated into soil a reduction in runoff of 40 and 59% was needed for N and P losses from a tall fescue + microclover lawn to be equivalent to a non-compost amended soil supporting a well fertilized tall fescue lawn. Use of compost as a soil amendment resulted in quicker lawn establishment and darker color, when compared to non-amended soil receiving a mineral fertilizer. Biosolid composts containing high amounts ammonium severely reduce the establishment of clover in tall fescue + micrclover seed mixture.Item Local lettuce: heat tolerant romaine cultivars and vermicompost soil amendment to increase sustainability in the Mid-Atlantic(2014) Wallis, Anna Elizabeth; Walsh, Chris S; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Local production of lettuce in the Mid-Atlantic utilizing heat-tolerant romaine cultivars and vermicompost soil amendment has the potential to significantly increase sustainability of agriculture. Heat tolerant cultivars would facilitate season extension into the summer. Vermicompost, compost produced using earthworms, may increase yield and quality of lettuce crops. This research tested a system incorporating these two practices. Success was assessed on lettuce yield and quality of lettuce across three seasons (spring, summer, and fall) and food safety risk of vermicompost. Several of the heat tolerant cultivars showed marketing potential when grown in the summer. Vermicompost did not significantly increase lettuce performance, but trends indicate that it may help, especially at higher rates. No food safety risk was associated with tested materials.