Publications

We performed laboratory experiments using water flowing through soil to mimic a contaminated groundwater scenario, where the contamination included both trichloroethylene (TCE) and perfluoroalkyl acids (PFAAs) such as may be found at historic fire fighter training areas.  TCE was found to bind (i.e., sorb) the PFAAs, such that it slowed PFAA movement through the soil.  Similar to our previous work, chemical oxidant were found to change PFAA mobility in the soil. Link to Article

We performed laboratory experiments using contaminated groundwater.  The goal of this research was to assess if a mixed-metal oxide electrochemical cell could be used to remediated perfluoroalkyl acid (PFAA) contaminated groundwater.  Electrochemical treatment was determined to be an effective means of remediation of PFAAs, particularly for the longer chain length PFAAs. Link to article

We performed laboratory experiments using water flowing through soil to mimic a contaminated groundwater scenario.  The goal was to determine if chemical oxidants were viable remediation strategies for perfluoroalkyl acids (PFAAs), which are common contaminants at historic fire fighter training areas.  Based on our experimental work, chemical oxidants don’t destroy PFAAs (i.e., not a good remediation approach), but they do change PFAAs movement, where some chemical oxidants caused faster movement and other chemical oxidants caused slower movement; explanations for mobility changes are discussed. Link to article

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Reprinted (adapted) with permission from article. Copyright 2015 American Chemical Society

In this study, we used simulations to evaluate weather, home performance, and evaporative condenser efficiency (energy and water use) for five California climate zone; additionally, the effect of household-level greywater reuse, as it impacted water consumption, was evaluated.  The goal of this study was to determine if evaporative condensers were a comparatively better approach to home air conditioning, and if so, under what climatic conditions.  Unsurprisingly, evaporative condensers used more water than traditional A/C units (which could be offset through greywater reuse), however they were also noticeably more energy efficient in hot arid climates. Link to article

Building and Environment--copper coil--10.1016--j.buildenv.2013.07.007

This was a field study to assess a new approach to point-of-use drinking water treatment, which could be used in developing countries, remote locations, or emergency situations.  The goal of this study was to determine if the new treatment approach using a silver-coated surface could produce water that is safe to drink, meaning that it is pathogen free and has acceptable amounts of silver.  We found that the new treatment approach produced pathogen-free water for more than two months, however than silver concentrations were higher than desired. Link to article

Biosand filters (BSFs) are appropriate-technology point-of-use drinking water treatment method that has been used in developing countries to improve drinking water quality and reduce the incidence of water-borne diseases.  In this study, we had placed 30 BSFs in Kenyan households and monitored the BSF performance for 6 months; the goal was to determine factors that influence their performance. BSFs were found to improve water quality (turbidity and fecal coliforms), particularly for comparatively dirty river water. However, we also found that the BSF were a less effective treatment approach in larger households or household where children were involved in the drinking water collection process. Link to article

Size exclusion chromatography (SEC) separates molecules based on molecular volume and can be coupled with online inductively coupled plasma mass spectrometry (ICP-MS) to explore size dependent metal–natural organic matter (NOM) complexation.  The goal of this study was to explore sample collection, processing, and analysis factors that would impact the data quality.  Stormwater runoff samples were analyzed as examples of the approach; sample processing and data interpretation recommendations are made. Link to article

Particle size and density will substantially affect how a particle moves through the environment or an engineered treatment.  The goal of this study was to develop and demonstrate a new fractionation approach that would yield information on both particle size and density; metal concentrations in stormwater samples from various land uses were used as a demonstration case.  Highway runoff was generally found to have higher dissolved metal concentrations, which are expected to be responsible to detrimental effects. Link to article

Environmental Science--Processes and Impacts--10.1039--c3em30612g

When it rains on a paved surface, the runoff typically contains pollutants including metals.  In this study, we collected 38 samples from roadways to understand factors that affect particle characteristics.  We found that particles characteristics pose challenges to conventional settling- or size-based treatments: 1) particle densities were less than the typical assumed values; 2) particles were generally not spherical or smooth; and 3) particles exhibited moderate surface charge which may prevent aggregation. Link to article

Kayhanian--10.1016--j.scitotenv.2012.08.077

In this Engineers Without Borders (EWB) project, we traveled to Uganda, partnered with a Ugandan NGO, and evaluated drinking water sources and potential point-of-use (POU) drinking water treatment options. While all of the tested systems effectively removed pathogens, cultural appropriateness and education were the most important drivers of project acceptance. Link to article

Automobiles have been previously identified as sources of various pollutants, including metals.  The goal of this study was to determine the metals that originate from tires and brakes. Tires were found to produce elevated zinc, lead, and copper concentrations, while brakes were identified by a number of metals including copper.  Select brake samples contained very high cadmium concentrations (e.g., 1000-times higher than typical brakes; Cd is highly toxic), which were likely a result of cadmium-coated brake rotors. Link to article

In this study, nine road-associated particle samples were collected and separated into size fraction based on particle diameter. In order to separate the very small particles, we adopted a biomedical method called a cell sorter.  By analyzing the separate fractions, we determined that the smallest particles contained elevated chromium, nickel, copper, zinc, and lead concentrations, and that human sources were indicated for these metals.  The very small particles will likely be challenging to remove.  Since human sources were indicated, targeting the source may be a good approach for reducing the pollution. Link to article

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