The Grainger College of Engineering

Student researchers find household biosand filters plus iron nails equals virus-free drinking water

12/17/2009

Socorro, a Mayan community of 450 in the highlands of southwestern Guatemala, is afflicted with acute and chronic diarrheal illnesses, soil-transmitted helminthes (worm) infections, and subsequent malnutrition. During the first months of winter rains, diarrheal rates in the children of Socorro exceed 75%. In 2007, Socorro called the University of Illinois branch of Engineers Without Borders (EWB-UIUC) for help. The response? An innovative project that will likely bring clean water to every Socorro household by fall 2010.

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Socorro, a Mayan community of 450 in the highlands of southwestern Guatemala, is afflicted with acute and chronic diarrheal illnesses, soil-transmitted helminthes (worm) infections, and subsequent malnutrition. During the first months of winter rains, diarrheal rates in the children of Socorro exceed 75%. In 2007, Socorro called the University of Illinois branch of Engineers Without Borders (EWB-UIUC) for help. The response? An innovative project that will likely bring clean water to every Socorro household by fall 2010.

 

(l to r) Ian Bradley, graduate researcher, with Peter Maraccini and Kimberly Parker, undergraduate project leads. They are standing behind a concrete biosand filter painted with Mayan designs to appeal to users. It can produce about 20 liters of clean water every use.
(l to r) Ian Bradley, graduate researcher, with Peter Maraccini and Kimberly Parker, undergraduate project leads. They are standing behind a concrete biosand filter painted with Mayan designs to appeal to users. It can produce about 20 liters of clean water every use.

A team of U of I students, including civil and environmental engineering (CEE) student leaders Sheila Markazi and Billy Nichols, went to Socorro for initial site assessments in December 2008 and spring 2009. The team designed a centralized system, but unfortunately the required land could not be purchased.

 

In summer 2009, the community and the team, with help from a local, culturally sensitive non-governmental organization (NGO), decided to pursue household-scale water treatment. Five EWB-UIUC civil and environmental undergraduates—Kimberly Parker and Peter Maraccini (project leads), with Alyssa Sohn, Emily Van Dam, and Ofelia Romero—will travel to Socorro during the 2009-2010 winter break. Working with the NGO, they will teach the small community team how to construct, operate, and maintain 150 (one for each family group) $30 concrete, iron-amended biosand filters (BSFs). After about 30 weeks, at a rate of five per week, Socorro could have its first reliable source of safe drinking water and no waterborne bacterial and viral diseases.

For 15 years, BSFs have been used effectively to strain out bacterial pathogens, protozoa, and helminthes from drinking water, but viruses, which are approximately 100 times smaller than bacteria, slip through. Enter EWB-UIUC undergraduates Parker, Maraccini, Markazi, Kevin Swanson and graduate researcher Ian Bradley, with their research adviser, Thanh (Helen) Nguyen, an assistant professor of the environmental engineering and science, who all found a great research opportunity in Socorro’s waterborne diseases.

Could the low-virus-removal problem be solved with rusty nails? Iron nails (zerovalent iron) added to the BSF sand layer, will rust, producing iron oxide and hydroxides. These positively charged oxides efficiently adsorb virus particles, removing them from the water. As the adsorption sites are filled, the iron oxides fall off the nails and expose new iron material, which rusts and creates new iron oxide adsorption sites to remove still more viruses. The process passively regenerates itself to indefinitely remove viruses. The iron oxides are caught in the sand once they fall off the nails and do not enter the filtered drinking water.

Test columns using iron filings throughout the sand (left), in a discrete layer (right), and a control (middle).
Test columns using iron filings throughout the sand (left), in a discrete layer (right), and a control (middle).

The few existing studies that have tested virus reduction using zerovalent iron-amended BSFs have considered only a particular virus or aspect of filtration. In April 2009, the CEE team was awarded a $10,000 grant from an Environmental Protection Agency program called P-3 (People, Prosperity, Planet)--Promising Research Ideas, one of only 20 nationwide, to examine multiple aspects of virus reduction using zerovalent iron-amended BSFs, in both small- and large-scale experiments with model organisms (MS-2) and human pathogenic viruses (rotavirus). They began in May. On the small scale, the team pumped water containing model viruses through glass columns filled with sand mixed with 10 percent iron filings and saw a 99.99% virus removal—the World Health Organization standard. As the experiment has continued and the iron has corroded further, more iron oxides have formed, with a 99.9999% removal rate.

Such promising results raise more questions: What is the optimal number of nails and placement—concentrated in a layer or spread throughout the sand? How long do they need to be in contact with the water? Does local contaminated water contain enough oxygen for nails to rust, or do its microorganisms remove too much oxygen for the rusty-nail idea to work? Will Guatemalan nails remove viruses without affecting the water’s pH, color, or taste? The CEE team is addressing these questions. Best responses could solve the waterborne disease problem in Socorro and developing communities around the world.

“First and foremost, we want to help Socorro,” Maraccini says.  “But we also want them to help us to demonstrate that our idea will be effective in real world situations.”

The team will be flown to Washington, D.C., sometime this spring to compete for the $75,000 EPA-Phase II¬-Implementation grant. A follow-up trip to Socorro to evaluate filtered water quality and community response is planned for May 2010.

Peter Maraccini, Kimberly Parker, and Ian Bradley contributed to this story. Professors Nguyen and Bruce Litchfield supported the EPA P-3 grant application. More than 50 EWB-UIUC members volunteered their time, donated, and raised almost $24,000 through fundraisers, the University of Illinois, EWB, Wuqu’ Kawoq and St. John’s Catholic Chapel. This money, together with the $10,000 EPA P-3 grant, will fund the 150 zerovalent iron-amended BSFs for Socorro.
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Contact: Celeste Arbogast Bragorgos, director of communications, Department of Civil and Environmental Engineering, 217/333-6955.
Writer: Joyce Mast

If you have any questions about the College of Engineering, or other story ideas, contact Rick Kubetz, Engineering Communications Office, 217/244-7716, editor.
 

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This story was published December 17, 2009.