Evaluating and Designing Effective Arsenic Treatment Technology for Small, Low-Income Communities in California

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./nWhile 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./nIron 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./nThe 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./nLastly, 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.

Advisor: Gadgil, Ashok J