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2016 Clarke Prize Honoree

Mark Sobsey

Mark D. Sobsey, Ph.D.
Kenan Distinguished Professor of Environmental Sciences and Engineering in the Gillings School of Global Public Health at the University of North Carolina at Chapel Hill (UNC)

View the 2016 Clarke Prize Lecture here.

The National Water Research Institute (NWRI) is pleased to announce that environmental engineer, Mark D. Sobsey, Ph.D., Kenan Distinguished Professor of Environmental Sciences and Engineering in the Gillings School of Global Public Health at the University of North Carolina at Chapel Hill, will be the twenty-third recipient of the NWRI Athalie Richardson Irvine Clarke Prize for excellence in water research. Sobsey's efforts have directly influenced the development of guidance and policies by prominent public health safety organizations like the U.S. Environmental Protection Agency (EPA), Centers for Disease Control (CDC), and World Health Organization (WHO).

"It is a great honor to receive this prestigious prize and join the distinguished group of past recipients," said Sobsey.

Pioneer in Water Treatment Technology

With a career spanning over 45 years, Sobsey has been an international leader and pioneer in the fields of public health microbiology and environmental virology, with a focus on water, sanitation, food, and hygiene. Early on, he developed an innovative filtration technique to selectively concentrate viruses from water. Known as the MDS filter, it was found to be more effective than conventional filters (which involved extensive, complex procedures to filter and coagulate microbes from large volumes of water) and, ultimately, helped develop a better understanding of the occurrence, concentration, and public health significance of viruses in the environment. The results of his research led to the development of the EPA's Groundwater Treatment Rule, which standardized practices in the U.S. to detect and control the presence of microbial pathogens (particularly viruses) in well water. Prior to this rule, the leading cause of waterborne disease was outbreaks from groundwater. His work on the development of filter techniques to concentrate and examine viruses in groundwater has become the standard for the water industry.

"The award of the Clarke Prize to Mark Sobsey," said Dr. George Tchobanoglous, Professor Emeritus of the University of California Davis and Chair of the Clarke Prize Selection Committee, "is in recognition of an illustrious career hallmarked by fundamental inquiry, the development of analytical methods and techniques, and the application of research findings and scientific principles to the solution of practical environmental problems."

Sobsey's efforts to develop improved methods to detect and control numerus waterborne viruses influenced the Surface Water Treatment Rule (SWTR) under the EPA's Safe Drinking Water Act. A key question during the development of the SWTR was what requirements were needed to inactivate viruses (chemically alter viruses so they cannot cause infection) found in water supplies from sources like lakes and rivers. The answer turned out to be CT values, which describe the disinfectant concentration (C) multiplied by the contact time (T) needed to inactivate viruses. CT values were stablished for virus inactivation with the SWTR and subsequent Enhanced Surface Water Treatment Rule and Long-Term Enhanced Surface Water Treatment Rules. These values are derived largely from the meticulous experiments and comprehensive studies of various viruses and chemical disinfectants conducted in Sobsey's laboratory.

Leader in Urban Water Sustainability

Among his more recent work, Sobsey was awarded a pilot research grant in 2015 to evaluate waterborne antibiotic resistant bacteria in Nicaragua and North Carolina. As part of the this effort, Sobseys' team will examine the extent to which antibiotic-resistant fecal bacteria, including E. coli and Klebsiella pneumonia, have caused illness in hospital patients and are being released into the environment through hospital sewage. Another study, which received funding from the National Science Foundation (NSF), commenced in 2015 to investigate how long Ebola can survive in feces and raw sewage, and the best means to inactivate it by chemical disinfection. This work involves the use of a genetically modified strain of Ebola that is not infectious to humans, animals, or other viruses.

A dedicated humanitarian, Sobsey also actively works with governments and Non-governmental organizations (NGOs) to develop low-cost drinking water treatment options at the household level in rural or less developed areas. In Cambodia, for example, where many lack access to improved drinking water sources and diarrheal diseases are widespread, Sobsey and his team tested and modified several types of ceramic filters for the reduction of waterborne pathogens. As a result, a locally produced, low-cost ceramic filter was implemented by several NGOs, and over 100,000 households in Cambodia use them for drinking water treatment. Similar efforts are underway in other countries. Another innovation of Sobsey's has been the development of a simple, low-cost test to determine if water is contaminated with feces. The test involves placing a water sample and user-friendly bacteriological medium (one that is not boiled or autoclaved, and can be incubated at temperatures typical of tropical environments) within the plastic bag, incubating it overnight, and then examining it for bacterial growth. If bacteria are present at unsafe levels (per the WHO guidelines for safe drinking water), users either can treat the water or find an alternative resource. The final cost for this simple water quality test is expected to be less than a dollar, making it affordable for communities in developing regions and after natural disasters like floods. Notably, the test influenced the United Nations to include a water quality goals as part of its Sustainable Development Goals to improve the lives of people everywhere.

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