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Arsenic: out of groundwater and into concrete

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pumping water.jpg
 
Researchers have invented a system that filters arsenic out of water cheaply. They’re now working with cement and concrete companies to figure out a way to embed the resulting sludge in building materials. 

In Bangladesh and West Bengal in India, over 60 million people drink groundwater that’s contaminated with naturally occurring arsenic. In some cases, the arsenic exceeds 1000 parts per billion (ppb) -- the World Health Organization’s recommended maximum limit for arsenic in drinking water is 10 ppb. We’re actually witnessing the largest case of mass poisoning in history

“A lot of technologies to remove arsenic on the community- and household- scale have been donated. But if you go to these villages it’s like a technology graveyard,” Ashok Gadgil of Lawrence Berkeley National Laboratory says in a news release. “One study found that more than 90 percent failed within six months, and then were abandoned to rust in the field.”

So, Gadgil and a UC Berkeley team led by Susan Amrose came up with Electrochemical Arsenic Remediation (ECAR), which binds arsenic using iron dissolved in water. It works effectively, cheaply, and it’s easy to maintain; and just as importantly, they’ve also conceptualized a business model for locals to implement the tech in the long term. They’re hoping to shorten the standard time lag between invention and commercialization from 18 to 10 years -- and they’re on track. The team started working on the concept in 2005, and now they’re planning a trial to filter 10,000 liters of water every day in rural sites over 15 months. 

  • ECAR consists of a container that can hold 600 liters of water pumped in directly from a nearby well. 
  • Inside, it’s fitted with a series of steel plates, and when a small voltage runs through the plates, that quickly dissolves iron in water, forming a type of rust. 
  • Arsenic binds to the rust as it forms, and then it falls to the bottom of tank, where it’s filtered out and collected as rusty sludge. 
  • The treated water is then pumped out, ready to drink. 

Indian company Luminous Water Technologies has licensed ECAR and plans to bring it to villages throughout India and Bangladesh. The team is also working on partnerships with local cement and concrete companies to do research on embedding the hazardous sludge in building materials. The waste doesn’t make the concrete dangerous, though they’re testing to see if it affects the material's strength. “We find in early tests that it’s very well stabilized, and the arsenic is not getting back into the environment,” Amrose says. “We expect and hope this form of sludge management will be viable and pass environmental approvals for market scale-up.” Until then, Luminous will dispose of the waste according to current guidelines.

Amrose adds: "I think stabilizing hazardous waste in concrete is something that's going to become more common. It makes sense, because there are so many roads being built in India right now.”

The technology has already been tested at a rural high school in Dhopdhopi, south of Kolkata, New Scientist reports, and now the team plans to start a year-long trial where local people manage the filtration themselves. They envision a village-owned micro utility, and Luminous would operate and maintain the utility and sell the water. “Other technologies have failed because there is no system of incentives or money or knowledge to keep them running,” Amrose says. “The key difference with ECAR is that it was designed to fit within a local system aimed at achieving successful social placement -- so a flow of funds pays for ongoing operation, maintenance, and social marketing, without turning it into privatized water.”

Arsenic-contaminated groundwater is also found in the U.S., and the team has just received a grant to test ECAR in California.
 
For more information and images of the tech, see the video presentation below.
 
 


Image: Susan Amrose via LBL

— By on March 29, 2014, 2:13 PM PST

Janet Fang

Contributing Editor

Janet Fang has written for Nature, Discover and the Point Reyes Light. She is currently a lab technician at Lamont-Doherty Earth Observatory. She holds degrees from the University of California, Berkeley and Columbia University. She is based in New York. Follow her on Twitter. Disclosure