Laboratory Assessment of Ferrate for Drinking Water Treatment

A laboratory assessment of ferrate (Fe(VI)) for drinking water treatment was conducted, including batch and continuous flow experiments on natural water samples. In batch experiments, ferrate preoxidation enhanced the removal of ultraviolet light-absorbing compounds (UV254; absorbance at 254 nm) by subsequent coagulation in some water samples, while some samples showed no improvement. Ferrate oxidation was not found to have negative impacts on subsequent coagulation. In continuous flow experiments, ferrate preoxidation improved finished water turbidity, UV254 absorbance, and disinfection by-product formation as compared with no preoxidation and to preoxidation with permanganate. However, improvements were similar in magnitude to those achieved by adding the same mass of ferric iron in place of ferrate prior to a formal coagulation step, in one water study. Particulate iron resulting from Fe(VI) reduction was effectively destabilized and removed via coagulation and filtration. Ferrate may be a viable technology for drinking water treatment depending on raw water quality and treatment goals

Comparison of ferrate and ozone pre-oxidation on disinfection byproduct formation from chlorination and chloramination

This study investigated the effects of ferrate and ozone pre-oxidation on disinfection byproduct (DBP) formation from subsequent chlorination or chloramination. Two natural waters were treated at bench-scale under various scenarios (chlorine, chloramine, each with ferrate pre-oxidation, and each with pre-ozonation). The formation of brominated and iodinated DBPs in fortified natural waters was assessed. Results indicated ferrate and ozone pre-oxidation were comparable at molar equivalent doses for most DBPs. A net decrease in trihalomethanes (including iodinated forms), haloacetic acids (HAAs), dihaloacetonitrile, total organic chlorine, and total organic iodine was found with both pre-oxidants as compared to chlorination only. An increase in chloropicrin and minor changes in total organic bromine yield were caused by both pre-oxidants compared to chlorination only. However, ozone led to higher haloketone and chloropicrin formation potentials than ferrate. The relative performance of ferrate versus ozone for DBP precursor removal was affected by water quality (e.g., nature of organic matter and bromide concentration) and oxidant dose, and varied by DBP species. Ferrate and ozone pre-oxidation also decreased DBP formation from chloramination under most conditions. However, some increases in THM and dihaloacetonitrile formation potentials were observed at elevated bromide levels

An inclusive Research and Education Community (iREC) model to facilitate undergraduate science education reform

Funding: This work was supported by Howard Hughes Medical Institute grants to DIH is GT12052 and MJG is GT15338.Over the last two decades, there have been numerous initiatives to improve undergraduate student outcomes in STEM. One model for scalable reform is the inclusive Research Education Community (iREC). In an iREC, STEM faculty from colleges and universities across the nation are supported to adopt and sustainably implement course-based research – a form of science pedagogy that enhances student learning and persistence in science. In this study, we used pathway modeling to develop a qualitative description that explicates the HHMI Science Education Alliance (SEA) iREC as a model for facilitating the successful adoption and continued advancement of new curricular content and pedagogy. In particular, outcomes that faculty realize through their participation in the SEA iREC were identified, organized by time, and functionally linked. The resulting pathway model was then revised and refined based on several rounds of feedback from over 100 faculty members in the SEA iREC who participated in the study. Our results show that in an iREC, STEM faculty organized as a long-standing community of practice leverage one another, outside expertise, and data to adopt, implement, and iteratively advance their pedagogy. The opportunity to collaborate in this manner and, additionally, to be recognized for pedagogical contributions sustainably engages STEM faculty in the advancement of their pedagogy. Here, we present a detailed pathway model of SEA that, together with underpinning features of an iREC identified in this study, offers a framework to facilitate transformations in undergraduate science education.Peer reviewe

Models of classroom assessment for course-based research experiences

Course-based research pedagogy involves positioning students as contributors to authentic research projects as part of an engaging educational experience that promotes their learning and persistence in science. To develop a model for assessing and grading students engaged in this type of learning experience, the assessment aims and practices of a community of experienced course-based research instructors were collected and analyzed. This approach defines four aims of course-based research assessment—(1) Assessing Laboratory Work and Scientific Thinking; (2) Evaluating Mastery of Concepts, Quantitative Thinking and Skills; (3) Appraising Forms of Scientific Communication; and (4) Metacognition of Learning—along with a set of practices for each aim. These aims and practices of assessment were then integrated with previously developed models of course-based research instruction to reveal an assessment program in which instructors provide extensive feedback to support productive student engagement in research while grading those aspects of research that are necessary for the student to succeed. Assessment conducted in this way delicately balances the need to facilitate students’ ongoing research with the requirement of a final grade without undercutting the important aims of a CRE education

Laboratory Assessment of Ferrate for Drinking Water Treatment

A laboratory assessment of ferrate (Fe(VI)) for drinking water treatment was conducted, including batch and continuous flow experiments on natural water samples. In batch experiments, ferrate preoxidation enhanced the removal of ultraviolet light-absorbing compounds (UV254; absorbance at 254 nm) by subsequent coagulation in some water samples, while some samples showed no improvement. Ferrate oxidation was not found to have negative impacts on subsequent coagulation. In continuous flow experiments, ferrate preoxidation improved finished water turbidity, UV254 absorbance, and disinfection by-product formation as compared with no preoxidation and to preoxidation with permanganate. However, improvements were similar in magnitude to those achieved by adding the same mass of ferric iron in place of ferrate prior to a formal coagulation step, in one water study. Particulate iron resulting from Fe(VI) reduction was effectively destabilized and removed via coagulation and filtration. Ferrate may be a viable technology for drinking water treatment depending on raw water quality and treatment goals

Modeling Crude Oil Fate and Transport in Freshwater

Accidental contaminant spills in surface freshwater drinking sources put the public at risk, lower consumer confidence, and are costly to clean up. Although crude oil is commonly transported in close proximity to drinking water supplies, much of the research has focused on the fate and transport of crude oil in marine and riverine systems, not reservoirs. This study illustrates an application of a proactive spill modeling method to simulate crude oil fate and transport in a reservoir using a combination of laboratory and modeling investigation. Dissolution trends of benzene, toluene, and ethylbenzene from hypothetical accidental input scenarios were estimated by solid-phase micro-extraction combined (SPME) with gas chromatography mass spectrometry (GC/MS) methods. Laboratory dissolution trends informed inputs to a hydrodynamic and water quality model, CE-QUAL-W2, which simulated the fate and transport of the crude oil components within a reservoir with a focus on water quality impacts at the drinking water intake. The method can be applied to proactively quantify and scientifically guide emergency response planning and management of drinking water reservoirs in the event of an crude oil accidental spill

Proactive modeling of water quality impacts of extreme precipitation events in a drinking water reservoir

Extreme precipitation events are of concern to managers of drinking water sources because these occurrences can affect both water supply quantity and quality. However, little is known about how these low probability events impact organic matter and nutrient loads to surface water sources and how these loads may impact raw water quality. This study describes a method for evaluating the sensitivity of a water body of interest from watershed input simulations under extreme precipitation events. An example application of the method is illustrated using the Wachusett Reservoir, an oligo-mesotrophic surface water reservoir in central Massachusetts and a major drinking water supply to metropolitan Boston. Extreme precipitation event simulations during the spring and summer resulted in total organic carbon, UV-254 (a surrogate measurement for reactive organic matter), and total algae concentrations at the drinking water intake that exceeded recorded maximums. Nutrient concentrations after storm events were less likely to exceed recorded historical maximums. For this particular reservoir, increasing inter-reservoir transfers of water with lower organic matter content after a large precipitation event has been shown in practice and in model simulations to decrease organic matter levels at the drinking water intake, therefore decreasing treatment associated oxidant demand, energy for UV disinfection, and the potential for formation of disinfection byproducts