A major challenge in integrating high penetrations (>20%) of solar- and wind-energy rests in the grid's ability to cope with the intrinsic variability of these renewable resources. Although such high levels of penetration may be a decade or two away in most operating regions, we must find measures to manage the variability of these sources, especially when conventional market-based approaches are exhausted or ineffective. Furthermore, besides assuring reliability, effective integration of high levels of solar- and wind-power can reduce the `hidden' environmental costs and emissions associated with larger than necessary backup capacity. With large-scale PV plants (>250 MW) becoming significant generators on the grid in the near future, system operators became concerned about the plants' inherent variability, and questions were raised regarding the predictability and reliability of the output from such PV plants. In the first part of this research, the variability in the power output of six PV plants in the United States and Canada, with a total installed capacity of 195 MW (AC), is characterized. A new metric called the Daily Aggregate Ramp (DAR) is introduced to quantify, categorize, and compare daily variability across multiple sites. With this metric, and by harmonizing for climatic differences across the plants, we quantified the effect of geographic dispersion in reducing the cloud-induced power fluctuations. In addition, the reduction in variability was assessed by simulating a step by step increase of the plant size at the same location, using individual inverter data. Our data analysis showed maximum ramp rates 0.7, 0.58, 0.53, and 0.43 times the plant's capacity for 5, 21, 48, and 80 MW (AC) plants, respectively. After the variability in plant outputs was understood and quantified, we investigated algorithms for operating Energy Storage Units (ESU) to perform ramp rate control at the plant level. This task is designed to support proposed plans of grid balancing authorities to deal with ramps of variable energy resources (i.e., solar and wind). ESUs can be used to mitigate penalty fees caused by sharp ramps and perhaps allow for additional revenue streams by participating in grid balancing markets (e.g. frequency regulation). Consequently, we focused on building and optimizing ESU dispatch models for controlling ramp rates of individual PV plants within predetermined levels. The model comprised dispatch strategies tailored to specific fast response ESU technologies (e.g., flywheels, capacitors, batteries). The optimization involved trial and error testing of different combinations of ESU technologies, power and energy capacities, dispatch strategies and violation reduction requirements. For four PV plants (5, 21, 30.24 and 80 MW) in various North American locations, we found a required ESU power capacity of 2.2, 9, 12 and 22 MW respectively, to mitigate 99% of the violations of a 10%/minute ramp rate limit. These ESU capacities may add capital costs of about $0.35-0.63 per Watt PV for the 80 MW plant and $0.56-0.94 per Watt PV for the 5 MW plant. Lowering the mitigation requirement to 90% reduces the necessary ESU power capacity (and per Watt PV costs) to 1.1 MW ($0.27), 4.4 MW ($0.27), 6.4 MW ($0.27) and 10.8 MW ($0.18), respectively. Curtailment of power at the inverter during upward ramps reduces the number of violations even further and effectively decreases the necessary ESU capacity to approximately: 0.8, 3.1, 4.5, and 7.6 MW (for the 90% violation mitigation). It is noted that the reported ESU capacity additions and associated costs are based on the assumption of no forecasting or only a one-minute ahead forecasting of cloud-induced solar variability. If forward time forecasting is available, the optimization we developed should result in lower ESU capacity requirements as gradual ramp rate controls could be implemented in advance. Another way to reduce the costs associated with ramp-rate controls is to use the ESU for other revenue-generating activities, such as frequency regulation for which markets exist in different operating regions (e.g. the Real-Time Market of the New York Independent System Operator (NYISO)). Since ramp rate violations in the various facilities we studied, occurred in less than 2% of the time during the year, such additional uses of ESUs are possible.

abstract: Iodide (I-) in surface and groundwaters is a potential precursor for the formation of iodinated disinfection by-products (I-DBPs) during drinking water treatment. The aim of this thesis is to provide a perspective on the sources and occurrence of I- in United States (US) source waters based on ~9200 surface water (SW) and groundwater (GW) sampling locations. The median I- concentrations observed was 16 μg/l and 14 μg/l, respectively in SW and GW. However, these samples were rarely collected at water treatment plant (WTP) intakes, where such iodide occurrence data is needed to understand impacts on DBPs. Most samples were collected in association with geochemical studies. We conclude that I- occurrence appears to be influenced by geological features, including halite rock/river basin formations, saline aquifers and organic rich shale/oil formations. Halide ratios (Cl-/I-, Br-/I- and Cl-/Br-) were analyzed to determine the I- origin in source waters. SW and GW had median Cl-/I- ratios of ~3600 μg/μg and median Br-/I- ratios of ~15 μg/μg. For states with I- concentration >50 μg/l (e.g., Montana and North Dakota), a single source (i.e., organic rich formations) can be identified. However, for states like California and Texas that have wide-ranging I- concentration of below detection limit to >250 μg/l, I- occurrence can be attributed to a mixture of marine and organic signatures. The lack of information of organic iodine, inorganic I- and IO3- in source waters limits our ability to predict I-DBPs formed during drinking water treatment, and new occurrence studies are needed to fill these data gaps. This is first of its kind study to understand the I- occurrence through historical data, however we also identify the shortcomings of existing databases used to carry out this study. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2018

A time-series of erodibility measurements and physical and biological sediment properties was used to evaluate spatial and temporal variability in cohesive bed erodibility and controls on erodibility in the York River estuary, VA. Two sites near Clay Bank displayed dramatic seasonal variations in bed erodibility while a third near Gloucester Point displayed a more consistent level of low erodibility. Total bed solids fraction and cohesive sediment grain size were not correlated with bed erodibility. The surficial sediments were characteristically composed of 2% to 50% sand supported in a mud matrix. The total solids fraction of the bed was shown to be a function of sand fraction, complicating its use as a measure of bed consolidation. The solids fraction of the mud matrix was calculated to evaluate changes in consolidation independent of sand content. An evaluation of data from multiple studies available in the literature demonstrated that when a large range of data was considered, the solids fraction of the mud matrix provided a better correlation to erodibility than did the total solids fraction. However, the range in solids fraction of the mud matrix in York River sediments was quite small and no significant relationship was found locally between this parameter and bed erodibility. Common proxies for bioadhesion including colloidal carbohydrate concentration, extracellular polymeric substance concentration, and organic content were measured to evaluate the influence of biostabilization on bed erodibility. In contrast to the results of many published works studying erodibility on mudflats, these bioadhesion proxies did not exhibit systematic variation in either space or time and were not correlated to bed erodibility. The seasonal timing of erodibility maxima and presence of laminations during periods of highest erodibility indicated that bioturbation was not responsible for increases in erodibility during the winter and spring at Clay Bank. Although not quantified in this study, anecdotal evidence from sediment cores and seabed camera images suggest that biological reworking and repackaging may alter bed cohesivity and structure potentially influencing the relationship between erodibility and bed solids fraction. Periods of rapid deposition, as indicated by the presence of thick sequences of laminated sediments, suggest that periodic sediment flux convergence processes are responsible for the observed seasonal cycle in bed erodibility at Clay Bank. High bed erodibility was associated with rapid deposition in the likely presence of the mid-estuary turbidity maximum while low erodibility was associated with sediment bypassing and decreased deposition in the absence of a local turbidity maximum. Finally, a consistent, low erodibility condition was observed at the Gloucester Point site for the majority of the study period and at Clay Bank in the summer and fall. A comparison of these data to other published data from the Chesapeake Bay indicated that the low erodibility background state may be characteristic of an “equilibrium” bed condition often present in many regions of the Chesapeake Bay. In the absence of recent, rapid deposition, the data set presented from the York River reasonably characterizes both the range and the profile information of the bed critical erosion stress for mid-depth, muddy regions in other similar estuaries.

abstract: The goal of this research was to study the effect of dilution on ammonium and potassium removal from real hydrolyzed urine. The performance of two natural zeolites, clinoptilolite and chabazite, was studied and compared with the help of batch equilibrium experiments at four dilution levels: 100%, 10%, 1% and 0.1% (urine volume/total solution volume). Further, the sorption behavior of other exchangeable ions (sodium, calcium and magnesium) in clinoptilolite and chabazite was studied to improve the understanding of ion exchange stoichiometry. Ammonium and potassium removal were highest at undiluted level in samples treated with clinoptilolite. This is a key finding as it illustrates the benefit of urine source separation. Chabazite treated samples showed highest ammonium and potassium removal at undiluted level at lower doses. At higher doses, potassium removal was similar in undiluted and 10% urine solutions whereas ammonium removal was the highest in 10% urine solutions. In general, chabazite showed higher ammonium and potassium removal than clinoptilolite. The result showed that ion exchange was stoichiometric in solutions with higher urine volumes. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2019

abstract: The objective of this study was to evaluate possible bioremediation strategy for aerobic aquifers by combining ZVI chemical reduction and microbial reductive dechlorination for TCE and ClO4-. To achieve this objective, continuous flow-through soil columns were used to test the hypothesis that bioaugmentation with dechlorinating enrichment cultures downstream of the ZVI injection can lead to complete reduction of TCE and ClO4- in aerobic aquifers. We obtained soil and groundwater from a Superfund site in Arizona. The experiments consisted of 205 cm3 columns packed with soil and ZVI, which fed 1025 cm3 columns packed with soil, biostimulated with fermentable substrates and bioaugmented. Aerobic groundwater was pumped through the ZVI columns. The ZVI reduced the oxidation-reduction potential (ORP) of groundwater from +150 mV to -190 mV. The reduced groundwater and biostimulation with fermentable substrates created anaerobic conditions in the bioaugmentation columns favorable for anaerobic microbial activity. Perchlorate (ClO4-) reduction to non-detectable levels occurred after biostimulation. Reduction of TCE to cis-dichloroethene, vinyl chloride and ethene was observed only after bioaugmentation. Within ~120 days of continuous columns operation, ethene was produced in the bioaugmentation columns this dechlorination activity was sustained until the end of experiments. The groundwater from the Superfund site had high concentration of sulfate (~1000 mg/L). Substantial sulfate reduction occurred in the bioaugmentation columns. Complete microbial reduction of TCE and perchlorate is usually challenging in the presence of high sulfate concentration; however, the strategy tested in this study suggests that a bioremediation scheme for simultaneous reduction of TCE and perchlorate in aerobic aquifers containing high sulfate concentration is feasible. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2019

Daily time series-based models are required to estimate the higher frequency fluctuations of nutrient loads and concentrations. Some mechanistic mathematical models can provide daily time series outputs of nutrient concentrations but it is difficult to incorporate non-numerical data, such as management scenarios, to mechanistic mathematical models. Bayesian networks (BNs) were designed to accept and process inputs of varied types of both numerical and non-numerical inputs. A Rank-Data distribution method (R-D method) was developed to provide large time series of daily predicted flows and Total Phosphorus (TP) loads to BNs driving daily time series estimates of T-P concentrations into Hyrum and Cutler Reservoirs, Cache County, Utah. Time series of water resources data may consist of data distributions and time series of the ranks of the data at the measurement times. The R-D method estimates the data distribution by interpolating cumulative failure probability (CFPs) plots of observations. This method also estimates cumulative failure probability of predictions on dates with no data by interpolating CFP time series of observations. The R-D method estimates time series of mean daily flows with less residual between predicted flows and observed flows than interpolation of observed flows using data sets sampled randomly at varying frequencies. Two Bayesian Networks, BN 1 (Bayesian Network above Hyrum Reservoir) and BN 2 (Bayesian Network below Hyrum Reservoir) were used to simulate the effect of the Little Bear River Conservation Project (LBRCP) and exogenous variables on water quality to explore the causes of an observed reduction in Total Phosphorus (TP) concentration since 1990 at the mouth of the Little Bear River. A BN provided the fine data distribution of flows and T-P loads under scenarios of conservation practices or exogenous variables using daily flows and TP loads estimated by R-D method. When these BN outputs were connected with the rank time series estimated by interpolation of the ranks of existing observations at measurement dates, time series estimation of TP concentrations into Cutler Reservoir under two different conservation practice options was obtained. This time series showed duration and starting time of water quality criterion violation. The TMDL processes were executed based on daily TP loads from R-D instead of mean or median values.

Perfluorooctanoic acid (PFOA) is persistent in environment due to its stable structure. It is also toxic to animals and human. The objective of this research is to remove PFOA with a non-thermal plasma reactor, anaerobic and aerobic bio-reactors, and their combination. Mineralization and defluorination (i.e., fluoride production) occurred in the plasma reactor. Neither PFOA removal nor fluoride production was observed in the bioreactors. In the plasma reactor with Argon as the carrier gas, 20 µM of PFOA in deionized (DI) water was removed to 4.22 and 4.04 µM, respectively, when the hydraulic retention time (HRT) was 0.21 s and 0.15 s, respectively. When the carrier gas was changed to Helium, PFOA was removed to 3.85 µM and 3.77 µM, respectively. Therefore, the carrier gas and HRT did not have significant effect on PFOA degradation. However, the carrier gas and HRT strongly affected the defluorination rate: 11% (for HRT = 0.21 s) and 6.5% (for HRT = 0.15) when Argon was the carrier gas, and 22% (for HRT = 0.21 s) and 8.6% (for HRT = 0.15 s) when Helium was the carrier gas. Consequently, a higher energy yield was achieved with Helium as the carrier gas (maximum of 11.3×10-11 mole F- production/J) than with Argon as the carrier gas (maximum of 6.43×10-11 mole F- production/J). Perfluoroheptanoic acid (PFHpA) and perfluorohexanoic acid (PFHxA) were observed in the effluent of the non-thermal plasma reactor by using liquid chromatography-tandem mass spectrometry (LC/MS/MS). The intermediates production rate was higher when argon was the carrier gas compared with Helium, probably because the degradation mechanisms are different for PFOA and their intermediates. / A Thesis submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2019. / March 25, 2019. / Includes bibliographical references. / Youneng Tang, Professor Directing Thesis; Bruce R. Locke, Committee Member; Clayton J. Clark Ⅱ, Committee Member.

Wastewater treatment plant (WWTP) effluents are major sources of pharmaceuticals and personal care products (PPCPs) in the environment and effluentdominated streams (EDSs) represent worst-case scenarios for PPCP exposures to aquatic organisms. The concentrations of PPCPs downstream from a WWTP can be altered by dilution and fate processes such as biodegradation, photodegradation and sorption. The relative importance of these processes depends on the individual PPCPs and environmental variables that vary seasonally. The primary objective of this study was to determine the concentrations of selected PPCPs in an EDS as a function of season and distance from a WWTP with the hypothesis being that the downstream attenuation of the PPCPs would vary based on their corresponding physicochemical properties. A secondary objective was to evaluate the ability of the constructed wetlands located between the plant and creek to reduce PPCP concentrations. Samples were collected seasonally from above and below the East Canyon Water Reclamation Facility (ECWRF) and within the constructed wetlands for selected PPCPs. Except for caffeine, downstream PPCP concentrations were higher than upstream, indicating that the ECWRF effluent is the major source of PPCPs in East Canyon Creek. Generally, the highest PPCP concentrations in the stream were observed in July and the lowest in May corresponding to the times of lowest and highest ratio of stream to effluent flows, respectively. Dilution was the major factor associated with the declining PPCP concentrations downstream of the ECWRF but the extent of decline varied between compounds suggesting other fate mechanisms also play a role. Sorption of PPCPs to wetland sediments was greater than stream sediments but overall the retention time within the wetlands was too short to significantly reduce the amount of PPCPs moving into the stream. The observed concentrations of individual PPCPs in East Canyon Creek were lower than those expected to negatively impact the health of aquatic organisms but mixture effects are still a potential concern.

This research describes the design, construction, and characterization of a novel annular gap bioreactor. The bioreactor was conceived as a tool for the shear-based control of activated sludge floc particle size in batch and continuous-run experiments. Initial experiments on the feasibility of cultivating aerobic granular sludge in the bioreactor are described. The bioreactor was found to experience turbulent Taylor vortex flow, rather than laminar Couette flow, at all rotational speeds tested. This flow regime is the result of inner cylinder rotation. Despite turbulent flow conditions, the bioreactor was found to behave approximately as a plug-flow device when not aerated, and as a complete-mix reactor when aerated. Floc size control was found to depend on bioreactor rotational speed for two sludges tested, with higher rotational speed leading to smaller particle size. Three experimental attempts at aerobic granular sludge cultivation in the annular gap bioreactor are described in this study. Although none of the three attempts was successful at producing aerobic granules, the experiments allowed critical control issues related to bioreactor operation and influent composition to be identified and addressed. The Bacterial and Eukaryal population dynamics during each run were tracked with denaturing gradient gel electrophoresis and rDNA sequence analysis, using methods developed or streamlined in the course of this research. The foundational work described in this study culminated in the development of a series of protocols and recommendations for the next phase of aerobic granular sludge investigation with this novel annular gap bioreactor.

Groundwater-surface water interactions can substantially influence the quality of surficial water bodies and are thus important when investigating ecological health of and climate change impacts on an area. However, data collection can be hindered when the location is remote and/or legally protected. This paper presents a methodology to implement minimallyinvasive field techniques at a remote and protected location that allows preliminary identification of the relationship between groundwater and surface water. Great Smoky Mountains National Park was selected as the study area as it is subjected to some of the highest rates of acid deposition in the country. Ecological damage is evident in several areas, including Ramsay Prong, a typical fourth-order stream located on the Tennessee side of the park. Ramsay Prong is evaluated on the basis of discharge, water quality, geochemistry, and stable isotopes at six points along the channel. It should be noted that increasing drought conditions occurred in the basin over the course of this study, providing an opportunity to evaluate the situation of low baseflow. Results indicate that storage capacity in the headwaters is insufficient to supply typical baseflow volume during extended dry periods, whereas sufficient alluvium exists at the bottom of the catchment to capture and recharge the basin water supply. A shallow fracture network likely provides long flowpaths for water to travel toward the basin bottom. Furthermore, baseflow is supplied by interflow as well as shallow groundwater storage; the portion of baseflow comprised by interflow increases with increasing antecedent precipitation. Diffuse groundwater recharge occurs mainly in the headwaters where steep slopes dominate the topography, while focused recharge occurs in bedrock depressions within the reaches and at the end of the channel. These observations, coupled with geochemical and isotopic data, indicate that neutralization of acidic inputs is best accomplished in the lower elevations of the basin. It is recommended that future studies investigate the ecological impacts of reduced precipitation in terms of acid neutralization capabilities along Ramsay Prong.