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Purely, Water

From polymer membranes and in situ testing to simple pumps and clay pots, researchers are working across the technology spectrum to improve water quality

By Jackie Powder

For the lucky, water is a healer, a cooler, a clear-as-glass bonding of hydrogen and oxygen. It's there for the taking—from the tap, from the hose, from ubiquitous plastic bottles—a seemingly endless supply to cleanse, quench and refresh.

The unlucky—the 1.2 billion people who lack access to safe drinking water—may walk miles to get water of any kind, water that may be laced with deadly contaminants.

From a public health perspective, clean safe water is the ultimate preventive. It's a defense against illness, including waterborne diarrheal-related diseases that claim the lives of 1.8 million people each year, most of them children under 5. "There still are not a lot of places on this planet where you can open up a tap and drink the water," says John Groopman, PhD, chair of the Department of Environmental Health Sciences (EHS) at the Bloomberg School.

Places like slums on the outskirts of Lima, Peru, where nearly a million squatters live in ramshackle structures perched high above the city, cut off from the municipal water and sewer system. Where up to 40 families might rely on a single hose to collect several days worth of water that they store at home in unprotected buckets. Where children play near pits of untreated waste.

"What we take for granted here, water coming to us 24/7, is a constant struggle for these people," says EHS associate professor Kellogg Schwab, director of the School's Center for Water and Health. Last year he traveled to Lima's peri-urban settlements to assess water quality as part of a collaborative research project with the School's Department of International Health and found that more than 20 percent of diarrheal illnesses in children are caused by norovirus. He and his team evaluated the feasibility of a relatively simple solution: a chlorine-based disinfectant, and narrow-necked water storage containers to prevent recontamination, which are now being widely used to prevent diarrheal sicknesses in children. In addition, doctoral candidate Sharon Nappier trained Peruvian technicians to test and monitor water quality at a molecular biology lab established by International Health faculty.

The School's activities in Peru—from identifying the norovirus to recommending practical solutions to defend against it to starting a local training program—provide a glimpse into the world of water and public health.

"The issues of water and sanitation are as big as virtually anything else in the public health field, whether it's malaria or other infectious diseases," says M. Gordon "Reds" Wolman, PhD, the B. Howell Griswold Jr. Professor of Geography and International Affairs at Johns Hopkins.

Researchers with the Johns Hopkins Center for Water and Health—which is based at the School and draws on collaborators from other Hopkins divisions as well—are working at high and low ends of the technology spectrum to improve water quality and access for people in the United States... and around the world.



Can polio and hepatitis A viruses concealed in untreated water squeeze through the 0.001-micron-sized pores of the tightly packed polymer membranes? What about salts and organic matter? The pathogens GiardiaE. coli and cryptosporidium?

In a water research lab at the School, investigations revolve around such questions, as scientists delve deeply into the workings of today's fastest growing water treatment technology: membrane filtration.

"I can easily tell you that this will become the conventional treatment of the future. There's no question in my mind," says EHS adjunct associate professor Joseph Jacangelo, PhD, REHS, who heads the School's membrane filtration research lab. There, investigators work to discover the mechanisms by which membranes remove contaminants, and evaluate different types of membranes for potential use in water treatment systems.

Their work comes at a time when water experts are sounding alarms about deteriorating water treatment and distribution infrastructure ("We have thousands of miles of pipes, some of which are 100 years old, that are not adequately maintained," Schwab notes), and warning that municipalities must develop improved disinfection technologies. Recent waterborne disease outbreaks traced to chlorine-resistant contaminants have highlighted weaknesses in the standard chemical disinfection process in use since the early 20th century.

Over the past two decades, advances in the efficiency and effectiveness of membrane filtration technology have moved steadily from lab concepts to demonstration-scale trials to full-scale water and wastewater treatment plants, says Jacangelo, national technical director with MWH, an environmental engineering company. As a replacement for an aging water plant or an additional treatment step in an existing plant, say water treatment experts, membrane filtration technology may help to prevent another disaster like the 1993 cryptosporidium outbreak in Milwaukee that killed more than 100 people and sickened 400,000.

"From a practical perspective, we look at how well membranes can work to better protect public health," Jacangelo says of his research.

The basics of membrane filtration involve pushing untreated water through tens of thousands of tube-shaped, organic polymer films with small pores on the surface. The system acts as a sieve, excluding microorganisms that are too big to squeeze through the pores, and allowing the filtered water to flow through the membrane.

When the technology came into use in the mid-1980s, a new system typically treated fewer than 1 million gallons of water a day. Today, Minneapolis Water Works has a plant that can treat over 65 million gallons of water with membranes that can that trap pathogens as small as the 0.025-micron viruses.

"The technology is expanding dramatically," in terms of interest from public water utilities, says Schwab. "Manufacturers claim certain capabilities and we evaluate different fiber matrixes in the lab to test for microbial removal and develop tests that utilities could put in place for selection purposes."

"The choice of membrane system," he says, "depends on what you're trying to remove." Microfiltration and ultrafiltration systems, for instance, use membranes with pore sizes of 0.1 and .01 microns, respectively, and apply 15 to 30 pounds of pressure per square inch to strain out microorganisms such as the parasite Giardia, as well as norovirus and enterovirus. A nanofiltration system, which relies on both size-exclusion and contaminant charge as mechanisms of removal, stops divalent ion salts, such as calcium. And reverse osmosis technology, which is used to desalinate seawater, employs very thin films and high pressure to remove all types of salts.

Thanks to tougher water quality regulations, and the fact that membrane filtration systems produce higher water quality at less cost than conventional treatments, Jacangelo expects the demand for membrane filtration systems to continue to grow.

"Almost any new water treatment plant today will consider membranes of some sort," he says. "A 20-million-gallon-a-day plant is now commonplace, whereas 20 years ago, it was really just a dream."

What Lurks Beneath?

When it comes to restoring polluted groundwater, the process begins by selecting the most effective method for destroying the offending chemical contaminants.

It's a complex and costly environmental challenge in the United States, where approximately 400,000 contaminated underground sites have been identified by the Environmental Protection Agency. The estimated cleanup costs in the coming decade alone? Between $500 billion and $1 trillion.

The School's Rolf Halden, PhD, PE, has developed a diagnostic tool, now under patent, that's aimed at identifying and deploying the most effective remediation technology available for treating tainted groundwater.

The EHS assistant professor describes the In Situ Microcosm Array (ISMA) as a "miniature underground lab" that would allow investigators to conduct onsite tests to compare cleanup strategies—in situ (in the soil)—for a contaminated aquifer. Measuring about 3 feet in length and 4 inches in diameter, the ISMA is designed to fit into any of the hundreds of thousands of monitoring wells that perforate the subsurface at contaminated sites across the United States.

"Having this tool could accelerate cleanup and potentially will turn more contaminated aquifers into safe drinking water resources," Halden says. "The unique thing is that during testing we don't remove the microbes and contaminants from where they're living." That's important, he explains, since removing a sample from its natural environment immediately changes both water chemistry and microbial activity, which in turn triggers "bottle effects" that are known to limit the value of lab results for predicting treatment effectiveness in field situations.

Halden's lab designed the ISMA with funding from NIH. Its prototype was built by the Instrument Development Group with the University's Department of Physics and Astronomy. Soon to undergo field-testing, the ISMA technology is sponsored by the Maryland Technology Development Corporation's (TEDCO) TechStart program and marketed by Hopkins' Technology Transfer Office.

From an economic standpoint, use of the ISMA could result in significant savings in the costly work of remediation. Currently, a chemical identified as effective in the cleanup process must be introduced into the subsurface via injection in a monitoring well for assessment. But the introduction of any substance at a monitoring station limits that station's usefulness for further testing and regulatory compliance monitoring.

In contrast, the ISMA technology does not compromise the monitoring area—which costs between $5,000 and $1 million to put in place—because all testing takes place within the device and no chemicals or bacteria are released.

Says Halden, "The device allows you to move around and test chemical treatments in different places without disturbing anything."


Appearing somewhat out of place in a 21st century research lab at the Bloomberg School, about a dozen pots made of terracotta clay and sawdust sit stacked against a wall. Some day, they may save lives in Central America.

The bucket-shaped pots—actually ceramic water purifiers—are the work of Potters for Peace. The nonprofit organization coordinates a global network of potters who provide rudimentary water treatment to communities in developing countries that lack potable water. The School's Center for Water and Health is evaluating the effectiveness of the ceramic filter system and other simple methods being used to treat water in the home. These low-tech methods are known as "point-of-use systems," and include everything from simple filtration devices to chemical disinfection solutions that are mixed with contaminated water.

Increasingly, point-of-use systems are gaining credibility as effective alternatives to centralized water treatment and distribution systems—particularly in isolated, rural communities and villages, where people rely on polluted sources or unsafe wells for water. Around the world, some 4,500 children die each day from unsafe water and lack of basic sanitation facilities.

"We're good at building big water plants. We've done that and in many cases it hasn't worked," says Charles O'Melia, PhD, professor emeritus and recently retired chair of the Johns Hopkins Department of Geography and Environmental Engineering (DoGEE). "The resources are not there to keep them up. They cost money to maintain and in many cases they haven't lasted very long."

Potters for Peace products were first used on a large scale in 1998 following Hurricane Mitch in Nicaragua. In the aftermath, local relief agencies distributed more than 5,000 filtration units. Since then, marginalized communities throughout the world with unsanitary water have used the pots. However, the system—along with other point-of-use treatments—has not undergone extensive scientific testing.

That's why the pots are sitting in a research facility at the School.

"We can use our sophisticated technology to evaluate a simple system in a lab-based environment," explains Schwab. "What do they really remove? What claims are being made?"

The pots are made from clay and sawdust, and the firing process burns fine pores over the entire surface, creating a completely porous vessel. Villagers can pour their unclean water through the filter—which will strain potentially deadly, diarrhea-causing bacteria like E. coliVibrio cholerae and Shigella—and collect the cleansed water in a storage container underneath.

"When constructed properly, they do a good job at removing bacteria," Schwab says. But the pot filters fail to strain viruses, including rotavirus, hepatitis A virus and norovirus; "They go straight through because they're much smaller," he notes. The filters can also clog and are relatively fragile. "But you can't not do a treatment process because it doesn't treat everything," Schwab says. "Maybe supplying a small community with a small-scale system is an approach worth evaluating."

Schwab, PhD, MS, says lab tests have confirmed that the filters are more effective at killing bacteria when they are dipped in colloidal silver after firing. A chemical interaction between the filter and the silver creates a germ-killing biocide.

Following evaluations in the lab, researchers plan to do field tests in Central America as well as epidemiological and cohort studies.

"We don't know very much about long-term use," says Schwab. "After a year, how many people are still using them? How many are still working?"

How Does Your Garden Grow?

In the hills of South Africa's KwaZulu-Natal province, elderly women walk more than the length of a football field to the nearest stream to fill up buckets of water. Then they heft the 60-pound buckets atop their heads and struggle to make the uphill trip back home. The water is crucial for their community vegetable gardens; the spinach, carrots, tomatoes, cabbage and onions they grow provide the main source of food for their fellow villagers.

Many of these women have lost sons and daughters to AIDS. They are left to care for their sick and dying children, raise their grandchildren, run households—all while making the exhausting trip for water each day.

Learning of the women's plight, a contingent of Johns Hopkins students set out to ease their water-toting burden—by organizing a project to build a simple watering system for the community gardens in the villages of Inchanga and Maphaphateni.

The 17-member multidisciplinary team with the Johns Hopkins chapter of Engineers Without Borders (EWB), which includes two students from the Bloomberg School, traveled to the villages in June 2006 to launch the project. They recruited agricultural engineer David Alcock as the project liaison. As a South African of English descent who grew up in the area speaking Zulu as a first language, Alcock first worked with the villagers to identify their most pressing water-related needs.

"Because of his prior relationships with the Zulu people, we didn't come into their community and say, 'This is what you need,'" says project participant Sharon Nappier, a PhD candidate in Environmental Health Engineering at the Bloomberg School.

The EWB group spent three weeks building "ram pumps" in the two villages. With Alcock's design updates to the basic technology, the student engineers were able to construct the pumps with locally available materials like car tire rubber and lead weights at a cost of less than $100 each. The system runs on the hydraulic energy of a stream and delivers water through pipes to storage tanks in the gardens.

The student volunteers spent long days digging ditches and laying the pipes. And the grandmother gardeners, who sometimes worked alongside them, served up daily lunches of phutu, a dish similar to grits, made with corn, beans, pumpkin, cabbage and sometimes meat.

In addition to helping with construction, Nappier and fellow Bloomberg student Maura Dwyer conducted a baseline health assessment, testing water from taps and in storage containers—trashcans, in some cases—and gathering data on diets and water usage.

Among the findings: Eighty percent of the survey participants in Inchanga and 40 percent in Maphaphateni said they do not have enough water to meet basic needs. In Inchanga, 46 percent of the respondents reported injuries from retrieving water.

When the Hopkins group returned to KwaZulu-Natal this past summer to follow up and install two more garden irrigation systems in other communities, the changes were dramatic. The communal gardens with the new systems were substantially larger and crop yields had increased to the point of surplus, enabling a number of new families to join as garden members.

Though health data hasn't yet been analyzed, the researchers expect to reduce exposure to schistosomiasis, a waterborne disease endemic to the area and caused by skin contact with parasitic worms. Now, instead of wading into an infected stream to collect water, the gardeners simply turn a spigot at the garden site.

And the more bountiful harvest should bring more nutritious diets in general, essential for AIDS patients to receive the full benefits of antiretroviral therapy, Nappier notes, adding, "It's another way we can help public health."


For most mothers in low-income Indonesian communities, the day starts by lighting a kerosene stove to boil water.

It's a daily practice that's been promoted by the government for decades as the best way to purify water in a country where 100 million people lack access to safe drinking water—and where waterborne diarrheal disease causes 20 percent of all deaths among children under 5.

"They have been receiving the message about boiling for so many decades that it's very entrenched in the culture," says Maria Elena Figueroa, PhD, director of the School's Global Program on Water and Hygiene.

Despite the consistent use of boiling, however, studies have found that in many Indonesian households the water contains fecal bacteria. Although boiling purifies the water, it doesn't provide protection from recontamination, which frequently occurs from improper storage.

That's where Air RahMat comes in. For 40 cents a bottle, the chlorine-based solution treats a month's worth of water, and unlike boiling, it leaves behind residual chlorine, which continues to protect the water from recontamination. The product is currently being introduced by the School's Global Program to middle- and low-income Indonesian communities through the USAID-funded Aman Tirta (Safe Water) Partnership. (The partnership is also being aided by the Centers for Disease Control and Prevention, the private sector and local nongovernmental groups.)

Despite Indonesia's obvious need for improvements in water quality, introducing a new water treatment method doesn't guarantee that it will be widely adopted. That's why the Global Program, a division of the School's Center for Communication Programs, works to understand behavior change in connection with safe water use and supports related awareness campaigns—within the context of government policies and services, and a community's cultural and social beliefs.

"Most of us working in public health know that the greatest benefit of safe drinking water for people in developing countries is to prevent diarrhea in young children," Figueroa says. But mothers in many communities around the world associate diarrhea in young children as part of normal development, teething, or even "sorcery."

"Sometimes the health connection with water is not a strong one," she says. "Seldom do you hear, 'Oh, he must have drunk unclean water, or he did not use soap to wash his hands after using the toilet or before eating.'"

When it came to "selling" Indonesians on the benefit of Air RahMat, the researchers took a pragmatic approach, emphasizing its money- and time-saving benefits: lower kerosene costs and no more waiting for boiled water to cool.

After a year of promotions on television and radio and through community-based activities, residents of some North Sumatra districts are getting the message.

Ibu Yuyun, a mother of six, grandmother of one and a respected kader, or health educator, in her community in Petojo Utara, uses Air RahMat consistently. "Clean and safe water is a must," Yuyun said, when interviewed as part of an ongoing program assessment. "We, especially the baby, could get a disease if we don't use safe water."

Ibu Siti, who runs an orphanage for 25 children, said that Air RahMat is her "secret in stretching her budget."

The Aman Tirta Partnership Program will soon roll out the next stage of the project, which includes a national media campaign and expanded access to the product in 80,000 outlets. In addition, Robert Ainslie, the Global Program's representative in Indonesia, is working with the country's health officials to craft a national policy endorsing chlorine-based and other water treatment products as alternatives to boiling. "People need to receive a technology to fit their needs in their context," Figueroa says.