Editor’s note: The original illustration attached to this story was removed for internal reasons.
Arsenic is one of the most toxic elements in the Earth’s crust. It is widely distributed, and under certain geochemical conditions, it dissolves into groundwater, which then gets pumped out for human use. Arsenic presents the highest cancer risk of any regulated carcinogens among drinking water contaminants when the risk from each is ranked at its maximum allowable concentration.
In California, almost 300 public water systems deliver water containing high levels of arsenic, more than 10 parts per billion, or ppb, which is the maximum allowable limit set by the Environmental Protection Agency.
The well-accepted model of arsenic toxicity predicts that lifetime consumption of water with arsenic concentrations of 90 ppb leads to 6,300 excess internal cancers per 100,000 people. That would be like more than 2,000 excess internal cancers in the current student population of UC Berkeley — unacceptably high!
California’s arsenic problem is concentrated in our Central Valley, where small rural water systems serve disadvantaged, economically vulnerable and politically underrepresented communities. These rural communities lack the technical, managerial and financial capacities to obtain a public water supply that complies with the EPA’s allowable arsenic limit. Any California public water system or school that is out of compliance with water quality norms receives a “compliance order,” which requires compliance by a given deadline. The order comes, however, without any financial or technical support.
Current technologies on the market tend to be too costly or complex to implement for these communities. To ensure safe drinking water, these communities must revert to bottled water services, which are both costly and unsustainable. According to the Community Water Center, residents of rural California may spend up to 10% of their income on bottled water to avoid drinking from contaminated sources. “Point of Use” technologies, such as filters on individual faucets or below-the-sink treatment units, have been installed at the household scale, but their long-term effectiveness has proven challenging because the burdens of maintenance and waste disposal fall on each household. Thus, an affordable and effective technology at the community scale is needed.
In 2016, a public elementary school in Lemoore, California received a compliance order — for which the school was billed $113 for the costs for preparation and issuance — which set a deadline of July 2019 to find a long-term solution for its arsenic problem. In response, the superintendent applied for funds from the State Water Resources Control Board, partnered with California Polytechnic State University on a well project and hired consulting engineers to find an effective technical solution.
Yet, at the school, they are still relying on bottled water, which is not deemed a long-term solution. Not meeting the compliance order triggers a heavy fine, despite all the efforts and expenditures for attempting to reach a solution.
Our research group had invented and successfully developed a robust, inexpensive, highly effective arsenic-removal technology known as ElectroChemical Arsenic Remediation, or ECAR, to provide arsenic-safe drinking water for one of the worst arsenic-affected regions in the world: rural West Bengal, India.
ECAR was developed from a 0.2 liter beaker on a benchtop in Berkeley. It is now a fully functional plant with a daily capacity of 10,000 liters (operating since 2016) at a rural school near Kolkata, India, reducing the arsenic concentration from the initial 250 ppb to 3 ppb.
ECAR has become an integral part of a self-sustaining business model that recovers all costs, is environmentally benign and has integrated into the local community. Operated by an Indian licensee, the ECAR plant sells arsenic-safe drinking water at a life-changing price of four cents per gallon to the community, as well as offers it free to students and school staff.
ECAR was designed to remove arsenic at a very low cost and with very little energy. This optimization led to our selecting a chemical pathway with slow kinetics, operated in a slow semibatch process. These slow kinetics are inadequate for communities in California or elsewhere in the United States, where each household demands at least 100 gallons per day.
To address the needs of California for compactness and a higher throughput, our research group has worked hard in the past two years to invent the next generation of ECAR called Air Cathode Assisted Iron Electrocoagulation, or ACAIE. ACAIE chemistry is based on the electrolytic dissolution of a sacrificial iron anode and concurrently generates hydrogen peroxide at the cathode. The latter speeds up the reaction kinetics nearly 10,000 fold, allowing ACAIE to meet the high throughput rates demanded by California communities and those elsewhere in the U.S.
In addition to technological innovation designed for low-income populations, a key component to the success of our projects is local community engagement. We closely partner with social scientists to build on strengths within communities, create equitable local partnerships, promote co-learning and sharing resources across partners. In India, we worked with Jadavpur University, and in California, we are working with researchers in the UC Berkeley School of Public Health.
We plan to scale up the technology and conduct a field test of ACAIE at the school in 2020. The success of the field test would support a positive shift toward stopping the poisoning of our rural communities with arsenic and help California and the world meet the human right to safe water. Application of the deep knowledge and vibrant creativity in our great research universities can indeed change the world for the better. Our story serves as just one small illustration, and we are pleased to be a part of the change for a better future.
Dana Hernandez is a doctoral candidate in civil and environmental engineering at UC Berkeley. Ashok Gadgil is a professor of CEE and a senior faculty scientist at Lawrence Berkeley National Laboratory.