Grantee Research Project Results
Solving the Arsenic Problem in Rural California
EPA Grant Number: SV840384Title: Solving the Arsenic Problem in Rural California
Investigators: Gadgil, Ashok
Institution: University of California - Berkeley
EPA Project Officer: Aja, Hayley
Phase: II
Project Period: April 1, 2022 through March 31, 2024
Project Amount: $99,998
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2022) Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources
Description:
Several experts have envisioned a decentralized approach of water treatment for meeting the water needs on the scale of a community. This alternative approach can provide more utility and empowerment to each community regarding their drinking water quality. Electrochemical technologies for water treatment have many characteristics that make them attractive for this application. In our research we have reported on the innovative use of gas diffusion cathodes, or air cathodes, integrated with conventional iron electrocoagulation (Fe-EC) to speed up the arsenic removal process, while remaining affordable. Furthermore, to be successful, the technology must be adopted by the communities it intends to serve.
Our innovation of ACAIE (Air Cathode Assisted Iron-EC) lies in the replacement of the iron cathode in iron electrocoagulation (Fe-EC) with a carbon-based air-cathode to speed up the arsenic removal process relative to Fe-EC, allowing the operation of the reactor at a high charge dosage rate to rapidly remove Arsenic from the water by adsorption on polymerized Fe(III) oxyhydroxides. These are then separated and removed. This has worked well in our laboratory, but nowhere in the world has it been tested and demonstrated in the field, nor has its community acceptance evaluated even hypothetically.
Therefore, our objectives are to: 1) Operate ACAIE continuously and effectively reduce high arsenic concentrations for a 2-month duration in Allensworth, California; 2) Install sensors enabled for data collection and remote monitoring; 3) Produce an improved estimate of future cost of a mature ACAIE community-scale plant; and 4) Evaluate the community’s receptivity to ACAIE technology and engage community through a STEM education program.
Approach:
A lab-tested 600 LPH system of ACAIE will be commissioned at a field site in Allensworth, CA. Leveraging our recent (2016) successful experience of deploying a 10,000 LPD (2,000 L reactor volume) ECAR plant in India, we will design, construct, place, briefly operate, and monitor the 600 LPH ACAIE system in Allensworth in Year 1. This short trial will inform our decisions on design improvements for the longer field trial in Year 2. In Year 2, we will operate the ACAIE system for 2 months to verify long-term performance in removing arsenic to below EPA-MCL. We envision a compact system design for delivering 600 LPH of arsenic-safe water with a small spatial footprint. The stack of ACAIE reactors will be followed by the routine treatment train for suspended solids removal (by flocculation and filtration). Along with arsenic concentrations we will monitor flow rates, pH, turbidity, iron concentration, arsenic and H2O2 concentrations at various points in the treatment train, and the voltages, currents, and the total power consumption over prolonged operation.
As with any treatment to remove toxic substances, the waste will be managed appropriately. ACAIE waste production is a small amount of solid arsenic-bearing sludge, since ACAIE is, by design, a Zero Liquid Discharge (ZLD) technology.
In Year 1 we will sign a Memorandum of Understanding with our partner community to conduct our field test on a local farm. We plan to introduce in the local public K-8 school, teacher-approved and teacher-tested modules developed by us on STEM-based water-related learning, appropriate to the class-levels, as a way to approach community education and informational outreach.
In Year 2, we will also conduct an economic analysis, based on performance data, to estimate the total cost of removing arsenic from the water at a future (mature technology) community-scale plant
Expected Results:
The goals of this Phase II project are to evaluate the long-term efficacy and robustness of a 600 LPH ACAIE system to reduce arsenic concentrations starting with above 100 µg/L, in real groundwater, to below the 10 µg/L MCL, and assess feasibility in terms of costs, affordability and acceptability by our partner community. A management plan for safe handling of the sludge will be developed to comply with applicable EPA and State of California guidelines for disposal. Analysis of collected data will be shared with the local community, and eventually published in a scientific journal to share with the broader research community. Our results will be the first-ever field data-based cost estimates of operation and maintenance of a community-scale plant based on ACAIE. Conducting a two month field test of ACAIE in year 2 will allow the collection of scientific and engineering data to support the process of regulatory assessment (and possible eventual approval) of this technology for arsenic removal from water in small community systems.
Progress and Final Reports:
P3 Phase I:
Solving the Arsenic Problem in Rural California | 2020 Progress Report | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.