1,4-dioxane is a probable human carcinogen frequently found in water and wastewater systems at concentrations above the EPA one-in-one-million cancer risk level of 0.35 ug/L. 1,4-dioxane is not well removed through conventional treatment methods due to its polarity and resistance to biodegradation, especially when present at low (μg/L) concentrations. Cometabolic degradation of 1,4-dioxane has been achieved in groundwater remediation by stimulating bacteria carrying cyclic ether-degrading soluble diiron monooxygenases (SDIMOs) through the addition of simple alkane gases, such as propane. A recent pilot-scale study demonstrated that addition of such co-substrates prior to biological active filtration (BAF) holds potential as a novel potable reuse treatment approach that can effectively remove 1,4-dioxane. Characterization of the microbial communities associated with propane-induced cometabolism of 1,4-dioxane has largely been limited to culture or polymerase chain reaction (PCR)-dependent methods, which are highly limited in throughput, generally providing information about one organism or one gene at a time. Shotgun metagenomic sequencing is a high-throughput nontargeted means of broadly profiling microbial taxa and functional genes involved in various metabolic processes. In this thesis, methods for DNA extraction from granular activated carbon applied to full-scale BAF amended with propane for the purpose of 1,4-dioxane cometabolism were optimized and metagenomic sequencing was performed. Insights were gained into the microbes and functional genes involved in 1,4-dioxane biodegradation, furthering our understanding of a potentially powerful new water reuse treatment technology that effectively polishes recalcitrant contaminants. / Master of Science / Water reuse systems use advanced wastewater treatment technologies to treat wastewater to such high standards that it can even be used as a source for drinking water. Expanding water reuse is a vital means of protecting water resources, but the treatments can be very costly. Biofiltration is a reuse treatment technology in which water is filtered through media - such as activated carbon - that is commonly used in household filtration systems, providing surface area for the growth of beneficial microorganisms that can naturally biodegrade contaminants in the water. Some contaminants are more difficult to degrade than others, especially trace levels of pharmaceuticals and personal care products. One common manufacturing ingredient that ends up in wastewater and is difficult to biodegrade is 1,4-dioxane, a compound that is potentially carcinogenic to humans at μg/L concentrations when consumed via drinking water over a lifetime. It was recently discovered that adding propane to a biofilter can help to improve biodegradation of 1,4-dioxane down to very low levels. Propane acts as a co-metabolite, i.e., providing a food source on which 1,4-dioxane-degrading bacteria can thrive. In this study, DNA sequencing technology was applied to help identify the bacteria that are responsible for co-metabolic degradation of 1,4-dioxane in a granular activated carbon biofilter. The research was conducted at a demonstration-scale research facility that is investigating innovative ways to treat wastewater to levels that are suitable for recharging a groundwater aquifer that is used as a drinking water source. The main contributions of this study include an optimized protocol for obtaining DNA from the BAF media for DNA sequencing and new insight into the bacteria and enzymes involved in co-metabolic degradation of 1,4-dioxane.

Sustainable Built Environments Senior Capstone Project / Across the world, populations continue to grow while water supplies stay fixed. In the American Southwest, water supplies are at an all time low, yet warm, favorable conditions continue to lure residents to the area. With some of the country’s lowest fresh water reserves, it is imperative that changes are made to water usage trends and associated energy inefficiencies. An analysis of water usage in Tucson was conducted to evaluate potential solutions for reducing consumption and to correspondingly shrink energy usage. Case studies were investigated, census numbers were used to roughly calculate statistics, existing knowledge on water conservation techniques were researched, and alternative water filtration as well as distribution systems were scrutinized for their viability amongst current infrastructure. The potential to reduce water usage is greatest with the largest user of water in Tucson, the single-family residence. On average the single-family residence is capable of effectively saving nearly 25,000 gallons of water per year with efficient fixtures, another 25,000 gallons per year by reducing outdoor water use by half, and another 10,625 gallons by utilizing rainwater harvesting. Combine those savings and multiply them by the 225,000-240,000 single-family residents estimated to be in Tucson and the savings reach more than five billion gallons a year, effectively almost cutting water consumption in Tucson by a fifth. Further, to keep remaining usage impacts negligible, implementation of an indirect or direct potable water reuse system could satisfy populations for decades by reusing water that would normally be discarded as effluent. Water consumption must be curved so that it can satisfy a growing population’s needs. Amongst residents of Tucson, single-family residences have the greatest potential to reduce water and associated energy needs. Through conservation techniques, water harvesting, reducing outdoor water usage, and potable reuse, limited water supplies can satisfy future generations to come.

Groundwater plays a fundamental role in water resource sustainability in Virginia (USA), but overpumping has caused significant declines in the potentiometric surface in the Potomac Aquifer System (PAS). With water levels falling, communities are at risk of wells running dry, saltwater intrusion, and land subsidence. The Sustainable Water Initiative for Tomorrow (SWIFT) project is an aquifer long-term replenishment (ALTR) project that uses continuous recharge into the multi-layered confined aquifer system to restore the potentiometric surface over space and time and increase storage in the system. The SWIFT Research Center (SWIFT-RC) is a 1 million gallon per day (MGD) demonstration facility in Suffolk, Virginia that recharges the PAS through a multi-screen well. Addressing research questions about the impact of continuous, sustained recharge on aquifer systems is crucial to the long-term sustainability of an ALTR project. Quantifying how flow moves through the multi-layered system is necessary to communicate travel times and water quality impacts on the aquifer system. This work uses injectate as an intrinsic tracer, an in-situ flowmeter, and a bromide tracer test to evaluate how flow is distributed through the eleven screens in the recharge well and to assess how flow distribution changes over time. Typically, flow distribution in multi-screen wells is estimated only once over the length of a project and assumed to remain constant for modeling purposes; by measuring flow distribution using multiple methods over the course of the project, this work shows that flow distribution is not constant. In future ALTR projects, developing a consistent and robust monitoring plan to use injectate as an indicator of movement through the aquifer system, paired with other methods to monitor changes in flow distribution, will be a critical part of effectively evaluating how flow moves through the groundwater system. / Doctor of Philosophy / Groundwater plays a fundamental role in water resource sustainability in Virginia (USA), but overpumping has left the Potomac Aquifer System (PAS) depleted. With water levels falling, communities are at risk of wells running dry, adverse water quality changes, and even changes to the land surface due to subsurface settling. The Sustainable Water Initiative for Tomorrow (SWIFT) project is an aquifer long-term replenishment (ALTR) project that uses continuous recharge into the deep aquifer system to restore water levels and increase storage in the system. The SWIFT Research Center (SWIFT-RC) is a 1 million gallon per day (MGD) demonstration facility in Suffolk, Virginia that recharges the PAS through a multi-screen well. Addressing research questions about the impact of continuous, sustained recharge on aquifer systems is crucial to the long-term sustainability of an ALTR project. Quantifying how flow moves through the multi-layered system is necessary to communicate travel times and water quality impacts on the aquifer system. This work uses multiple methods to evaluate how flow is distributed through the eleven screens in the recharge well and to assess how flow distribution changes over time. Typically, flow distribution in multi-screen wells is estimated only once over the length of a project and is assumed to remain constant for modeling purposes; by measuring flow distribution using multiple methods over the course of the project, this work shows that flow distribution is not constant. In future ALTR projects, developing a consistent and robust monitoring plan to use recharge water itself as an indicator of movement through the aquifer system, paired with other methods to monitor changes in flow distribution, will be a critical part of effectively evaluating how flow moves through the groundwater system.

San Diego imports 80 to 90 percent of its water supply, depending on conditions during any particular year. This high level of imports and low diversity of water supply have combined with climate change to generate an urgent need for increased conservation and diversification of San Diego's water supply. Water reuse is one option to mitigate this problem. An attempt was made in the early 1990s to recycle wastewater but the public reacted badly due to a combination of bad public relations, perceived environmental justice issues, and a psychological phenomenon called the yuck factor. With improved public relations and education, the project might go through this year.

abstract: The objective of this research was to predict the persistence of potential future contaminants in indirect potable reuse systems. In order to accurately estimate the fates of future contaminants in indirect potable reuse systems, results describing persistence from EPI Suite were modified to include sorption and oxidation. The target future contaminants studied were the approximately 2000 pharmaceuticals currently undergoing testing by United States Food and Drug Administration (US FDA). Specific organic substances such as analgesics, antibiotics, and pesticides were used to verify the predicted half-lives by comparing with reported values in the literature. During sub-surface transport, an important component of indirect potable reuse systems, the effects of sorption and oxidation are important mechanisms. These mechanisms are not considered by the quantitative structure activity relationship (QSAR) model predictions for half-lives from EPI Suite. Modifying the predictions from EPI Suite to include the effects of sorption and oxidation greatly improved the accuracy of predictions in the sub-surface environment. During validation, the error was reduced by over 50% when the predictions were modified to include sorption and oxidation. Molecular weight (MW) is an important criteria for estimating the persistence of chemicals in the sub-surface environment. EPI Suite predicts that high MW compounds are persistent since the QSAR model assumes steric hindrances will prevent transformations. Therefore, results from EPI Suite can be very misleading for high MW compounds. Persistence was affected by the total number of halogen atoms in chemicals more than the sum of N-heterocyclic aromatics in chemicals. Most contaminants (over 90%) were non-persistent in the sub-surface environment suggesting that the target future drugs do not pose a significant risk to potable reuse systems. Another important finding is that the percentage of compounds produced from the biotechnology industry is increasing rapidly and should dominate the future production of pharmaceuticals. In turn, pharmaceuticals should become less persistent in the future. An evaluation of indirect potable reuse systems that use reverse osmosis (RO) for potential rejection of the target contaminants was performed by statistical analysis. Most target compounds (over 95%) can be removed by RO based on size rejection and other removal mechanisms. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2011

The world’s growing population is causing an ever increasing demand for clean safe drinking water. In some countries suitable sources of drinking water are becoming scarce and will not be able to satisfy future demand. Consequently, there is a need to find alternative sources of water that can be used for potable supply or to augment current sources. Advanced water treatment methods are now being examined to investigate whether treated domestic sewage effluent can be treated to drinking water standards and discharged upstream of a drinking water abstraction point; a process known as Indirect Potable Reuse (IPR). The aim of this project was to investigate biological activity associated with developmental exposure to IPR water at the various stages of treatment using zebrafish embryos. Embryos reared in water at different stages of the treatment process were observed for developmental abnormalities, and differences in gene expression (compared to an aquarium water control) were used to establish both the nature and persistence of these effects along the treatment process. In addition to the embryo assays, passive sampling devices, Pharmaceutical Polar Organic Integrative Sampler (Pharm-POCIS) were deployed over eight, four week periods to collect composite concentrated samples of some of the contaminants present in the effluent. These concentrated extracts were then used in an in vitro assay; an Enzyme Immunoassay (EIA) to measure the inhibition of prostaglandins (an indirect measure of inhibitors of cyclooxygenase activity). We compared our results of the bioassays with the large body of chemical analysis data recorded over a number of years from each of the treatments. The developmental exposures highlighted a low frequency of consistent abnormalities to the heart and spine, and also a lack of pigmentation. Gene expression analysis demonstrates the developmental stage of the embryo to have the greatest influence on global gene expression as opposed to the treatment. Single genes of interest included the two cytochrome P450s (cyp1a and cyp1b1) and somatolactin beta. Some of the pathways disrupted included steroid synthesis, retinol metabolism, tryptophan metabolism and melanogenesis. The latter was consistent with observations of some embryos devoid of pigment. Along the treatment process reverse osmosis seemed to cause the largest change to the gene expression. The extracts from less treated effluent inhibited prostaglandin production, however following reverse osmosis prostaglandin inhibition was greatly reduced. The chemical contaminantion is greatly reduced as the effluent progresses along the IPR treatment process, this is evident from both the chemical data and the biological assays. Reverse osmosis seems to have the greatest influence on the gene expression. The results have highlighted the importance of an appropriate control, to remove background noise.

Soil aquifer treatment (SAT) of treated wastewater performance was evaluated across published full-scale and lab-scale studies developing insights on the aquifer and operational factors that affect SAT efficacy. The goal of this study was to develop a basis for predicting the contaminant removal capabilities of any given aquifer during managed recharge with treated wastewater. Over 40 published SAT studies were reviewed and systematically compared to determine the influence of five major factors on contaminant removal performance: geologic composition, geochemical conditions, hydrogeological conditions, operational methods, and source water quality. Removal mechanisms for standard contaminants (dissolved and total organic carbon, nitrogen, and pathogens) were considered for each factor. By supplementing the theoretical understanding of contaminant removal in SAT systems with full scale and lab scale results, recommendations were developed for practical and effective SAT feasibility standards. SAT of standard contaminants was found to be most effective in aquifers with a water table below 20-meters. SAT was also most favorable for source water with 10 to 20-mg/L of bulk organics and less than 10-mg/L of total nitrogen. Moreover, extended residence times in the saturated zone provide little additional bulk organic and nitrogen removal for aquifers with vadose zones that achieve more than 85% of total bulk organic removal. The results of this study should enhance feasibility studies for future soil aquifer treatment projects, thereby facilitating the use of sustainable indirect potable reuse.

This study evaluates soil properties that impact the effectiveness of soil aquifer treatment (SAT) as a polishing step to the remove two classes of ECs from wastewater effluent: pharmaceuticals and personal care products (PPCPs), and engineering nanomaterials (ENMs). In recent years, it has been determined that elevated levels of emerging contaminants (ECs) are being released into the environment with wastewater effluent. ECs are proven to cause adverse environmental and health effects as a result of long-term exposure. It is important to evaluate sustainable solutions to improve the current methods of wastewater treatment to address these ECs. Soil aquifer treatment (SAT) is a sustainable, cost effect treatment alternative to advanced treatment at a wastewater treatment plant. SAT replenishes local groundwater supplies while allowing for indirect potable reuse, if contaminants of concern such as ECs can be effectively removed from the water. Since wastewater effluent can contain a variety of contaminants with myriad physical and chemical properties, understanding the potential of the aquifer itself to provide EC removal is a key step in establishing SAT as a viable treatment alternative. Peer-reviewed research studies were analyzed to determine the soil properties that affect the fate and transport of ECs in the aquifer environment. The data was complied to produce recommendations for an effective SAT site. Physical and chemical properties of the soil facilitate contaminant removal as the groundwater flows through the aquifer. This study determined that removal of ECs from effluent had a correlation with (1) high clay content, (2) small Darcy Velocity, (3) high soil organic matter content, and (4) low sand content. Based on the 6 peer-reviewed research studies reviewed, the removal of nanomaterials is affected by clay content and sand content, but not soil organic matter content. Conversely, the removal of PPCPs is affected by clay content and soil organic mater content, but not sand content. It can be concluded that two different removal mechanisms facilitate the removal of nanomaterials versus PPCPs; physical removal for nanomaterials and chemical removal (sorption) for PPCPs. Clay facilitates the removal of both contaminants. The small soil diameter of clay forms smaller pores in the soil media. This causes increased pore straining, while also restricting the flow through the soil, which increases the contact time between the soil particle and the ECs. Additionally, clay has a large surface area, which increases surface interactions, such as sorption, of the EC to the surface of the clay particle.

Optimal operation of water reclamation facilities (WRFs) is critical for an indirect potable reuse (IPR) system, especially when the reclaimed water constitutes a major portion of the reservoir's safe yield. It requires timely and informed decision-making in response to the fluctuating operational conditions, e.g., weather patterns, plant performance, water demand, etc. Advanced integrated modeling techniques can be used to develop reliable operational strategies to mitigate future risks associated with water quality without needing high levels of financial investment. The Upper Occoquan Service Authority (UOSA) WRF, located in northern Virginia, discharges nitrified reclaimed water directly into a tributary of the Occoquan Reservoir, one of the major water supply sources for Fairfax County. Among the many operational challenges at UOSA, one is to regulate the nitrate concentration in its reclaimed water based on the denitrifying capacity of the reservoir. This study presents an integrated model that is used to predict future reservoir conditions based on the weather and streamflow forecasts obtained from the Climate Forecast System and the National Water Model. The application captures the dynamic transformations of the pollutant loadings in the streams, withdrawals by the water treatment plant, WRF effluent flows, and plant operations to manage the WRF performance. It provides plant operators with useful feedback for correctly targeting the effluent nitrates using an intelligent process simulator called IViewOps. The platform is powered by URUNME, a new software that fully automates the operation of the reservoir and process models integrating forecasting products, and data sources. URUNME was developed in C#.NET to provide out-of-the-box functionality for model coupling, data storage, analysis, visualization, scenario management, and decision support systems. The software automatically runs the entire integrated model and outputs data on user-friendly dashboards, displaying historical and forecasting trends, on a periodic basis. This decision support system can provide stakeholders with a holistic view for the design, planning, risk assessments, and potential improvements in various components of the water supply chain, not just for the Occoquan but for any reservoir augmentation type IPR system. / Doctor of Philosophy / In an indirect potable reuse (IPR) system, reclaimed water from an advanced wastewater treatment facility is blended with a natural water source, such as a reservoir, to augment drinking water supply. Reliable operation of such a system is critical, especially when the reclaimed water constitutes a major portion of the withdrawals from the reservoir for treatment and distribution. One example of such an IPR system is the Upper Occoquan Service Authority (UOSA) water reclamation facility (WRF) which discharges its reclaimed water into the Occoquan Reservoir, a key water resource for Fairfax County. Integrated environmental modeling (IEM) provides a comprehensive approach towards the design and operation of water resource systems in which water supply, drainage, and sanitation are simulated as a single entity rather than independent units. In IEM, different standalone models, each representing a single subsystem, are linked together to analyze the complex interactions between various components of the system. This approach can be used for developing operational support tools for an IPR system to ensure timely and informed decision-making in response to the fluctuating conditions, e.g., weather patterns, plant performance, water demand, etc. The overarching goal of this research was to integrate different models and the data sources and develop a decision support system (DSS) to manage the UOSA-WRF performance. This resulting integrated model is used to predict future reservoir conditions based on the weather and streamflow forecasts obtained from the National Weather Service. The application runs various future scenarios to capture the possible variations of the pollutant loadings in the streams, withdrawals by the water treatment plant, WRF effluent flows, and plant operations and provide feedback to plant operators. The entire integrated model is operated periodically to output data on user-friendly dashboards, displaying historical and forecasting trends. The DSS provides stakeholders with a holistic view for the design, planning, risk assessments, and potential improvements in various components of the water supply chain, not just for the Occoquan but for any reservoir augmentation type IPR system.

Soil aquifer treatment (SAT), the removal of contaminants during percolation through soil, is a strategy employed in managed aquifer recharge (MAR), one method of indirect potable water reuse. As part of Hampton Roads Sanitation District's (HRSD) MAR project, The Sustainable Water Initiative for Tomorrow (SWIFT), a soil column study was performed using four columns filled with sand taken from the Potomac Aquifer System (PAS) as well as water from various stages in SWIFT's 1MGD demonstration facility. Two pairs of two columns were operated in series, simulating 3 days and 1 month of travel time through aerobic to anaerobic conditions. During Phase 1 of testing, each pair of columns was fed from different stages in the SWIFT treatment process. During Phase 2 of testing, one set of columns was spiked with a conservative tracer bromide, and several contaminants of emerging concern (CECs). The contaminants monitored during both phases included total organic carbon (TOC), nitrogen species, and the disinfection byproducts bromate and NDMA. During Phase 2 of testing, CECs, iron, arsenic, bromide, and sulfate were monitored in addition to those monitored during Phase 1. About 50% of the TOC was removed within 3 days of travel time, with no additional removal observed in 1 month. Nitrate was conserved in the 3-day columns, but completely removed after 1 month, indicating denitrification. Bromate and NDMA were reduced significantly in the 3-day columns and mostly non-detect in the 1-month effluent. Many of the spiked CECs were reduced significantly in the 3-day column indicating degradation. Three compounds exhibited some retardation through both columns but were not degraded. A few compounds, notably perfluorooctanoic acid (PFOA), showed no retardation or degradation. / Master of Science / In order to continue to meet the water demands of the future, potable reuse is a necessary and effective solution. HRSD's SWIFT project aims to create a sustainable source of drinking water through advanced treatment of its wastewater effluent and subsequent recharge of the Potomac Aquifer in a process known as managed aquifer recharge (MAR). During MAR, chemical and biological contaminants are attenuated or removed through a process known as soil aquifer treatment (SAT). HRSD installed pilot-scale soil columns at their 1MGD SWIFT demonstration facility to evaluate the potential removal of contaminants. During the study, removal of contaminants, both regulated and unregulated, was observed. This study demonstrated that SAT provides an effective environmental barrier against many contaminants and helped to inform the level of treatment necessary to protect public health during MAR potable reuse projects.