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Open Access Publications from the University of California

Scholarly Works (4 results)

  • Article
  • Peer Reviewed
UC Berkeley Previously Published Works (2022)
Small, low-income communities in the United States disproportionately lack access to safe drinking water (i.e. water that meets regulated quality standards). At a community level, the literature has broadly claimed that a major barrier to safe drinking water access is low technical, managerial, and financial (TMF) capacity. At a broader structural level, the environmental justice literature has shown that historical neglect of low-income communities of color has resulted in numerous water systems without the financial and political resources to meet water quality standards. This study investigates the contemporary processes by which distributive injustices persist in California's Central Valley. The study uses key informant interviews with a range of stakeholders, including employees at the state, county and community, non-profit organizations, and engineers, to understand why sustainable water quality solutions for small low-income communities remain such a challenge. The interviews are structured around a decision chain, which builds out the specific steps needed to go from a maximum contaminant level violation to remediation. The resulting decision chain makes visible the multiple steps at multiple stages with multiple actors that are needed to arrive at a solution to substandard water quality. It shows the numerous nodes at which progress can be stalled, and thus functions as a behind-the-scenes look at the (re)production of persistent inequalities. The complexity of the process shows why having the TMF capacity needed to get to a safe water system is not a reasonable expectation for most small community water systems. Inequalities are continually being produced and cemented, often by the very steps aimed towards remediation, thus making persistent disparities in safe drinking water access a de facto state-sanctioned process that compounds a discriminatory historical legacy.
    Cover page: Safe drinking water for small low-income communities: the long road from violation to remediationCreative Commons 'BY-NC-ND' version 4.0 license
    • Thesis
    • Peer Reviewed
    UC Berkeley Electronic Theses and Dissertations (2020)

    Arsenic contamination of groundwater continues to threaten access to safe and affordable drinking water for California’s most vulnerable small, socioeconomically disadvantaged communities. While arsenic treatment technologies exist, they remain out of reach for many. How does this disparity persist in California, the wealthiest state in the US and one of the world’s largest economies? This dissertation explores this question by studying why treatment remains out of reach for many, and what solutions can be developed to increase access to safe, affordable drinking water for all. These questions are approached by first evaluating how appropriate existing technologies are for small, low-income communities. Then, a novel technology called iron electrocoagulation, is adapted to and field tested in the Central Valley, and the process, outcomes, and community perceptions are analyzed. Finally, pathways and barriers to treatment as perceived by key stakeholders are evaluated.

    While treatment technologies exist, questions remain regarding what existing arsenic treatment technologies are appropriate (affordable and operable), and to what degree technological limitations contribute to the lack of access to sustainable arsenic treatment solutions. In addition, it is not understood how new technologies compare to existing technologies for use in this context. The questions outlined are evaluated using metrics that are relevant to small systems: operating costs, capital costs, and operating complexity. The results suggest that treatment flow rate and raw water quality are defining features impacting the potential of treatment technologies to meet the defined small system relevant metrics. Because of variability in flow rate and water quality, there is no single treatment technology that can be identified as appropriate in all cases. Recognizing the complexity of previous technologies, new technologies have emerged to simplify operation. One such technology investigated in this study, iron electrocoagulation (Fe-EC), was found to be well positioned to improve upon existing technologies at low flow rates (<100 gallons per minute), because its operating costs are more stable and it is easy to operate with variability in raw water quality. Finally, the results suggest that in some cases (at low flow rates) existing technological limitations contribute to the lack of sustainable treatment solutions due to complexities in operation and economies of scale required to meet affordability criteria.

    Iron electrocoagulation (Fe-EC) is an emerging treatment technology that has been tested at community scale in India. In research reported here, Fe-EC is investigated to use in the rural Californian (U.S.) context by identifying (and attempting to overcome) several limitations. Limitations of Fe-EC’s application in rural California that are considered in this work are: 1) Frequent electrode cleaning required to overcome rust accumulation is relatively labor intensive, 2) Electrolysis durations are long, reducing throughput for a given system size, 3) Particle separation after electrolysis is time consuming, and, 4) Waste needs characterizing per California standards. The strategies to overcome each of the above limitations are discussed. The strategies are evaluated by testing the modified version of classical Fe-EC under real-world conditions through a field trial on a farm in Allensworth, a small, low-income community in California. Results demonstrate that Fe-EC removed arsenic consistently below federal (and state) standards. We provided evidence that some of the technical limitations can be addressed, whereas overcoming limitation 1 needs further research. If limitation 1 can be met with future work, Fe-EC may be suitable for scale-up regarding arsenic-remediation applications in relevant California communities.

    The Fe-EC field trial in Allensworth is used as a case study to explore technology development in rural, low-income communities in the US. The study presents design criteria, including those used to modify the design from its original installation in India, interviews with community members to understand community perceptions, challenges faced in the field, and recommendations for field researchers working on low-cost drinking water technologies. Through the case study, a series of considerations are developed for field researchers interested in carrying out similar work in communities struggling with contaminated drinking water and in need of appropriate treatment solutions.

    Lastly, we assess stakeholders’ perceptions of the process, and pathways and barriers to develop sustainable water quality solutions in small, low-income communities in California. The study uses key informant interviews with a range of stakeholders, including employees at regulating agencies, nonprofits, engineers, and the county. The interviews are structured around a decision chain, which outlines steps needed to go from a maximum contaminant level violation to remediation. The resulting decision chain makes visible the multiple steps at multiple stages that are needed to arrive at a manageable solution to substandard water quality. It shows the multiple nodes of potential failure at which progress can be stalled, and thus functions as a behind-the-scenes look at the process of persistent inequalities. The complexity of the process suggests that having adequate technical, managerial, and financial (TMF) capacity to get from a maximum contaminant level violation to a safe water system is likely not viable or a reasonable demand for most small community water systems. Inequalities are continually being produced or cemented, and our study reveals that persistent disparities should be seen as a process instead of as a state or as a snapshot.

      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (2021)
      Small, low-income, and rural communities across the United States are disproportionately exposed to arsenic contaminated drinking water because existing treatment solutions are too expensive and difficult to operate. This paper describes efforts to overcome some barriers and limitations of conventional iron electrocoagulation (Fe-EC) to enable its use in the rural Californian (U.S.) context. Barriers and limitations of Fe-EC's application in rural California considered in this work include: 1) Frequent labor intensive electrode cleaning is required to overcome rust accumulation, 2) Electrolysis durations are long, reducing throughput for a given system size, and 3) Waste needs compliance with California standards. We report results from an investigation for overcoming these limitations via a field trial on a farm in Allensworth, a small, low-income, rural community in California. Our strategies to overcome each of the above barriers and limitations are respectively, 1) operating the Fe-EC reactor at high current density to result in sustained Fe production, 2) operating at high charge dosage rate with external H2O2, and 3) characterization of the arsenic-laden waste, and are discussed further in the paper. Main findings are: (1) Fe-EC removed arsenic consistently below the federal (and state) standard of 10 µg/L, (2) high current density failed to sustain Fe production whereas low current density did not, (3) electrolysis time decreased from > 1 hour to < 2 min with H2O2 dosing of 5 mg/L at higher charge dosage rates, (4) dilution of As-sludge is required to comply with State's non-hazardous waste status, and (5) discrepancies were observed between lab and field results in using current density to overcome labor-intensive electrode cleanings. Finally, implications of overcoming limitations to scale-up of Fe-EC in relevant California communities are discussed.
        Cover page: Adapting a drinking water treatment technology for arsenic removal to the context of a small, low-income California community
        • Article
        • Peer Reviewed
        UC Berkeley Previously Published Works (2020)
        Millions of people are exposed to toxic levels of dissolved arsenic in groundwater used for drinking. Iron electrocoagulation (FeEC) has been demonstrated as an effective technology to remove arsenic at an affordable price. However, FeEC requires long operating times (∼hours) to remove dissolved arsenic due to inherent kinetics limitations. Air cathode Assisted Iron Electrocoagulation (ACAIE) overcomes this limitation by cathodically generating H2O2 in situ. In ACAIE operation, rapid oxidation of Fe(II) and complete oxidation and removal of As(III) are achieved. We compare FeEC and ACAIE for removing As(III) from an initial concentration of 1464 μg/L, aiming for a final concentration of less than 4 μg/L. We demonstrate that at short electrolysis times (0.5 min), i.e., high charge dosage rates (1200 C/L/min), ACAIE consistently outperformed FeEC in bringing arsenic levels to less than WHO-MCL of 10 μg/L. Using XRD and XAS data, we conclusively show that poor arsenic removal in FeEC arises from incomplete As(III) oxidation, ineffective Fe(II) oxidation and the formation of Fe(II-III) (hydr)oxides at short electrolysis times (<20 min). Finally, we report successful ACAIE performance (retention time 19 s) in removing dissolved arsenic from contaminated groundwater in rural California.
          Cover page: Rapid and Efficient Arsenic Removal by Iron Electrocoagulation Enabled with in Situ Generation of Hydrogen Peroxide
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