UML Researchers Clear a Path to Clean Water

09/21/2018
By Edwin L. Aguirre

While working on her thesis in the central Philippines in 2004, Sheree Pagsuyoin watched villagers walk for miles to collect water for drinking, cooking and washing. Those living in more remote areas had to wait for water to be delivered via indigenous dugout canoes called “bancas.” Although access to clean drinking water has since improved significantly in this Southeast Asian nation, there is still a lot of work to do to deliver reliable and safe water to a greater number of people, says Pagsuyoin, now an assistant professor in UMass Lowell’s Civil and Environmental Engineering Department.

That’s why she decided to dedicate her life to researching ways to improve access to safe, clean water.

“I want to contribute to solving this universal problem,” says Pagsuyoin, who has a master’s degree in environmental engineering from the University of the Philippines, Diliman, and a doctorate in civil and environmental engineering from the University of Virginia.

“Water problems don’t recognize political or geographic boundaries; a problem in one area impacts another in many ways,” she notes.

In fact, in 2010, the U.N. General Assembly recognized access to safe, clean water and sanitation as a basic human right.

But according to the World Health Organization, in 2015, at least 2 billion people worldwide used drinking water sources contaminated with human waste, which can transmit infectious diseases such as cholera, dysentery, hepatitis A, typhoid and polio. Drinking contaminated water is estimated to cause more than 500,000 deaths, mainly of children, due to diarrhea each year. In addition, waterborne parasites, toxic chemicals and radiological hazards pose serious threats to drinking water.

In response, Pagsuyoin, along with teams of other faculty researchers from the Francis College of Engineering – led by Prof. Pradeep Kurup and Asst. Prof. Onur Apul of civil and environmental engineering and Asst. Prof. Ertan Agar of mechanical engineering – have embarked on projects that combine sustainability with cutting-edge technology to address these problems and help provide people with clean, easily accessible water.

Pagsuyoin is exploring the use of the seeds of Moringa oleifera, a fast-growing, drought-resistant tree widely cultivated in the tropical and subtropical regions of Africa, Asia and Latin America, for treating drinking water. Agar, Apul and Pagsuyoin are also designing an electrochemical system for removing harmful contaminants from water, while Kurup has developed an electronic “tongue” that can detect traces of toxic heavy metals in groundwater and soil that can cause physiological and neurological disorders.

“It is hard to overstate the importance of this work. Access to clean water is a fundamental need for all. These projects are critical to safeguarding this precious resource,” says Dean Joseph Hartman of the Francis College of Engineering. “I’m proud that our faculty, students and staff are tackling such an important problem and are helping improve the lives of people all over the world.”

A Sustainable, Eco-friendly Way of Disinfecting Water

In many parts of the world, untreated water from streams, rivers, ponds, lakes and the ground are the primary sources of drinking water, particularly in low-income regions, according to Pagsuyoin. “In these communities, the need for a low-cost, readily accessible water treatment method is especially critical in reducing incidences of waterborne diseases,” she says.

Pagsuyoin collaborated with researchers from De La Salle University in Manila, the Philippines, and George Washington University in Washington, D.C., to investigate the use of crushed moringa seeds for treating and disinfecting contaminated water via adsorption.

“Moringa seeds are known to contain proteins that have antibacterial and coagulant properties,” she says. “One tree will produce enough seeds to purify about 6,000 liters [1,600 gallons] of water. They are as effective as alum, and can reduce hardness and arsenic in water.”

However, the seeds also contain soluble organic matter that are released into the treated water and can serve as food for pathogenic microorganisms, causing them to regrow.

“The downside is that water treated by powdered moringa seeds cannot be stored for long periods of time,” notes Pagsuyoin.

To address this issue, researchers tested carbon-based adsorbent materials – activated charcoal, rice husk ash and ceramic beads – that would bind the seed protein tightly onto the materials’ surfaces and keep the unwanted organics from being released into the water.

“We observed the highest adsorption capacity with activated charcoal, followed by rice husk ash and then ceramics,” says Pagsuyoin. The team also used a nonpathogenic form of E. coli bacteria to show that the immobilized seed protein still retained its antibacterial property.

“The seed protein/carbon adsorbent combination can be used as a filter medium for creating a low-cost, portable biofilter,” says Pagsuyoin. This application is still under development.

Pagsuyoin and graduate student Akarapan Rojjanapinun are currently investigating other low-cost adsorbent membranes for removing trace pollutants in drinking water. These projects are in collaboration with Prof. Hongwei Sun of mechanical engineering and Earl Ada, Ph.D., of the university’s Materials Characterization Laboratory.

Very Persistent Chemicals

Americans enjoy one of the cleanest, safest and most reliable supplies of drinking water in the world. Yet traces of contaminants can still lurk in tap water from public water systems. These can range from microorganisms to disinfectants and disinfection byproducts, inorganic and organic chemicals and radionuclides.

Two man-made chemicals used in manufacturing industries, called perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), have recently attracted significant interest because of their increasing and widespread detection in the country’s water supply. These compounds have been used for decades in many industrial applications and commercial products, such as firefighting foams, flame-retardant and nonstick coatings, stain- and water-repellent fabrics, cleaning products, metal coatings, additives, surfactants and food packaging materials.

“Both chemicals are very persistent in the environment and in the human body – meaning they don’t break down and they can accumulate over time. The bioaccumulation and toxicity of these compounds can potentially lead to adverse health effects,” says Agar.

To date, several water treatment technologies, including photochemical oxidation, ultraviolet irradiation, adsorption and coagulation, have been developed to remove PFOS and PFOA in drinking water. “However, the effectiveness of these systems in eliminating the environmental and health risks has not reached a satisfactory level,” notes Agar.

This has motivated Agar, Apul and Pagsuyoin to develop a high-capacity, high-efficiency “capacitive deionization,” or CDI, system that would selectively remove PFOS and PFOA from water. This low-energy desalination method uses porous carbon electrodes to capture and remove salt from flowing saline water.

“Our project is currently in its very early stage,” says Agar, who directs the university’s Electrochemical Energy Systems and Transport Laboratory. He and his co-researchers recently received a $10,000 seed grant from UMass Lowell to support their project. Assisting them in the lab are incoming chemical engineering juniors Joseph Egitto and Jana Latayan of UML and UMass Amherst, respectively.

In the first part of the project, the team will design and develop a CDI setup for removing ordinary table salt (sodium chloride) from brackish water. Then they will attempt to remove bromide (a salt containing negatively charged bromine ions) from water, which will be used as a technology benchmark to accurately assess the feasibility of their proposal. In the final part, the knowledge obtained from earlier experiments will be applied to develop an electrochemical water treatment technology for the effective removal of PFOS and PFOA from natural surface water sources.

“If successful, our proposed system will provide access to clean, safe and secure water resources and help establish a healthy ecosystem,” says Agar.

A Taste for Sensing Danger

Kurup, who chairs the Department of Civil and Environmental Engineering, cites the recent water crisis in Flint, Mich., as an example of how even developed countries can face problems with water contamination.

The problem in Flint was caused by insufficient corrosion treatment of the water supply, which allowed lead to leach from lead water pipes into the city’s drinking water, exposing more than 100,000 residents to the neurotoxin.

“Flint’s drinking water had levels of lead hundreds of times higher than the EPA limit,” Kurup says.

Waste products from mining and industrial manufacturing as well as heavy use of pesticides have resulted in the accumulation of heavy metals in surface water, groundwater and soils in many cities and farms across the country. Long-term exposure to these pollutants through direct contact or the food supply has been linked to health problems involving the skin, kidneys and liver as well as the gastrointestinal tract and central nervous system.

To address the problem, Kurup and geotechnical engineering Ph.D. students Connor Sullivan and Susom Dutta will use the electronic tongue to rapidly test and analyze traces of heavy metals on-site and in real time. The E-tongue uses arrays of highly sensitive microelectrode sensors coupled with artificial intelligence to “taste” water and soil samples and to detect – and identify –  any heavy metals present, such as arsenic, cadmium, copper, chromium, iron, lead, manganese, mercury, nickel, selenium, thallium and zinc.

Research and development of the E-tongue has been supported with grants from the National Science Foundation (NSF) totaling nearly $740,000.

“The E-tongue will be simpler, faster, safer and more cost-effective compared with the traditional methods,” says Kurup. “It should cut the cost associated with field sampling and lab analysis by more than 50 percent.”

He says the E-tongue will limit the exposure of lab personnel to contaminated soil and water by avoiding the need for drilling and collecting samples. Since site investigators will get the test results more quickly, they can provide regulatory agencies with critical information needed for taking appropriate actions, such as issuing drinking-water advisories in a timely manner.

The technology can also be expanded to detect other types of toxins, making this approach applicable to such fields as biotechnology, pharmaceuticals and medical diagnostics, food and agricultural inspections, environmental monitoring, law enforcement and homeland security, he says.

Kurup has formed AquaTerrene, a spinoff company that is working to commercialize the E-tongue technology. The company is located in the UMass Lowell Innovation Hub in downtown Lowell.

“The university is currently exploring a licensing opportunity with a major environmental engineering company,” he says. “Our group is also working with the Army to develop a handheld E-tongue to allow soldiers to test water quality in the field.”